Co-reporter:Lisiqi Xie, Xiao Huang, and Bin Su
ACS Sensors June 23, 2017 Volume 2(Issue 6) pp:803-803
Publication Date(Web):April 12, 2017
DOI:10.1021/acssensors.7b00166
A portable amperometric ion sensor was fabricated by integrating silica isoporous membrane (SIM) and organogel composed of polyvinyl chloride and 1,2-dichloroethane (PVC-DCE) on a 3D-printed polymer chip. The detection of ionic species in aqueous samples could be accomplished by adding a microliter of sample droplet to the sensor and by identifying the ion-transfer potential and current magnitude at the water/organogel interface array templated by SIM. Thanks to the ultrasmall channel size (2–3 nm in diameter), high channel density (4 × 108 μm–2), and ultrathin thickness (80 nm) of SIM, the ensemble of nanoscopic water/organogel (nano-W/Gel) interface array behaved like a microinterface with two back-to-back hemispherical mass diffusion zones. So, the heterogeneous ion-transfer across the nano-W/Gel interface array generated a steady-state sigmoidal current wave. The detection of choline (Ch) and its derivatives, including acetylcholine (ACh), benzoylcholine (BCh), and atropine (AP), in aqueous samples was examined with this portable sensor. Using differential pulse stripping voltammetry (DPSV), the quantification of these analytes was achieved with a limit of detection (LOD) down to 1 μM. Moreover, the portable ion sensor was insensitive to various potential interferents that might coexist in vivo, owing to size-/charge-based selectivity and antifouling capacity of SIM. With this priority, the portable ion sensor was able to quantitatively determine Ch and its derivatives in diluted urine and blood samples. The LODs for Ch, ACh, AP, and BCh in urine were 1.12, 1.30, 1.08, and 0.99 μM, and those for blood samples were 3.61, 3.38, 2.32, and 1.81 μM, respectively.Keywords: choline; ion sensor; liquid/organogel interface; portable; silica isoporous membrane;
Co-reporter:Xiao Huang;Lisiqi Xie;Xingyu Lin
Analytical Chemistry January 3, 2017 Volume 89(Issue 1) pp:945-951
Publication Date(Web):November 29, 2016
DOI:10.1021/acs.analchem.6b04099
Metoprolol (MTP) is one of the most widely used antihypertensive drugs yet banned to use in sport competition. Therefore, there has been an increasing demand for developing simple, rapid, and sensitive methods suited to the identification and quantification of MTP in human biofluids. In this work, ultrathin silica nanochannel membrane (SNM) with perforated channels was employed to support nanoscale liquid/liquid interface (nano-ITIES) array for investigation of the ion-transfer voltammetric behavior of MTP and for its detection in multiple human biofluids and pharmaceutical formulation. Several potential interfering substances, including small molecules, d-glucose, urea, ascorbic acid, glycine, magnesium chloride, sodium sulfate and large molecules, bovine serum albumin (BSA), were chosen as models of biological interferences to examine their influence on the ion-transfer current signal of MTP. The results confirmed that the steady-state current wave barely changed in the presence of small molecules. Although BSA displayed an apparent blockade on the transfer of MTP, the accurate determination of MTP in multiple human biofluids (i.e., urine, serum and whole blood) and pharmaceutical formulation were still feasible, thanks to the molecular sieving and antifouling abilities of SNM. A limit of detection (LOD) within the physiological level of MTP during therapy could be achieved for all cases, i.e., 0.5 and 1.1 μM for 100 times diluted urine and serum, respectively, and 2.2 μM for 1000 times diluted blood samples. These results demonstrated that the nano-ITIES array behaved as a simplified and integrated detection platform for ionizable drug analysis in complex media.
Co-reporter:Xingyu Lin, Qian Yang, Fei Yan, Bowen Zhang, and Bin Su
ACS Applied Materials & Interfaces December 7, 2016 Volume 8(Issue 48) pp:
Publication Date(Web):November 18, 2016
DOI:10.1021/acsami.6b13772
In biology, all protein channels share a common feature of containing narrow pore regions with hydrophobic functional groups and selectivity filter regions abundant with charged residues, which work together to account for fast and selective mass transport in and out of cells. In this work, an ultrathin layer of polydimethylsiloxane (PDMS) was evaporated on the top orifices of charged silica nanochannels (2–3 nm in diameter and 60 nm in length) vertically attached to the electrode surface, and the resulting structure is designated as heterogeneous silica nanochannels (HSNs). As evidenced by voltammetric studies, the transport of ionic species in these HSNs was controlled by both hydrophobic rejection and electrostatic force arising from the top PDMS layer and from the bottom silica nanochannels, respectively. Anionic species encountered both hydrophobic rejection and electrostatic repulsion forces, and thus, their transport was strongly prohibited, while the transport of cationic species was permitted once the electrostatic attraction exceeded the hydrophobic rejection. Moreover, the magnitude of hydrophobic force could be regulated by the PDMS layer thickness, and that of the electrostatic force can be modulated by the salt concentration, solution pH, or applied voltage. It was demonstrated that the HSNs could be activated from an OFF state (no ion can transport) to an ON state (only cation transport occurs) by decreasing the salt concentration, increasing the solution pH, or applying negative voltages.Keywords: asymmetric wettability; electrochemical detection; gating; heterogeneous; multiforce; nanochannels;
Co-reporter:Lisiqi Xie, Xiao Huang, Xingyu Lin, Bin Su
Journal of Electroanalytical Chemistry 2017 Volume 784() pp:62-68
Publication Date(Web):1 January 2017
DOI:10.1016/j.jelechem.2016.12.007
•Building nano-ITIES array with the support of silica isoporous membrane•Sigmoidal steady-state current response due to the dominance of spherical diffusion•Negligible transmembrane resistance due to high pore density and ultrasmall thickness•Permselective ion transfer gated by electrical double layer effectMiniaturization of the interface between two immiscible electrolyte solutions (ITIES) brings the benefits of enhanced mass transport in comparison with the macroscopic ITIES, similar to those observed with an ultramicroelectrode. In this work, ultrathin free-standing silica isoporous membrane (SIM, 80 nm in thickness) consisting of a high density of perforative channels with a uniform size (2–3 nm in diameter) was used to construct nanoscopic ITIES (nano-ITIES) arrays. Electrochemical characterization of the nano-ITIES array by studying the ion-transfer voltammetric behavior of tetra-n-propylammonium (TPrA+) suggested the domination of hemispherical molecular diffusion. The effect of trans-membrane resistance on the heterogeneous ion transfer was investigated by varying the supporting electrolyte concentration in both phases, which was found to be negligible due to the ultrathin thickness and high channel density of SIM. In addition, the nano-ITIES array exhibited excellent charge selectivity towards ionizable species due to the overlap of electrical double layer in the ultrasmall silica channels, which could be modulated by the supporting electrolyte concentration, aqueous solution pH and channel surface modification. These findings provide the basis for the nano-ITIES array to be used in ion detection and separation.
Co-reporter:Qian Yang;Xingyu Lin;Yafeng Wang
Nanoscale (2009-Present) 2017 vol. 9(Issue 46) pp:18523-18528
Publication Date(Web):2017/11/30
DOI:10.1039/C7NR05924H
A molecular check valve is a nanomachine that enables unidirectional molecular transport. In this work, we report a novel molecular check valve fabricated by asymmetric modification of a silica nanoporous membrane (SNM) consisting of parallel nanochannels with a diameter of 2–3 nm. Asymmetric modification refers to the thermal deposition of hydrophobic polydimethylsiloxane (PDMS) only on one side of the SNM to generate hydrophobic nanoorifices. Such an asymmetric nanostructure, designated as PDMS-SNM, could synergistically exert a hydrophobic force on the molecules by PDMS nanoorifices and an electrostatic force by naked silica nanochannels, resulting in unidirectional molecular transport under specific circumstances. Typically, only positively charged molecules were able to transport across the PDMS-SNM from the PDMS nanoorifice side, while backward transport from the other side was prohibited. In the former case, positively charged molecules were subject to electrostatic attraction from naked silica channels, which could exceed the hydrophobic rejection from PDMS nanoorifices to pull the molecule across the PDMS-SNM. However, in the latter case the electrostatic attraction is no longer a driving force to overcome the hydrophobic rejection from PDMS nanoorifices to promote the molecular transport. On the other hand, the PDMS-SNM based molecular check valve can be shut down to prevent any molecular transport from either side of the PDMS-SNM under certain conditions, such as a high salt concentration or an appropriate pH (e.g., pH 3). We believe that it could be applied to convert natural fluctuation energy into directed motion, as well as to prevent backward transport in batteries and fuel cells.
Co-reporter:Weiliang Guo;Yanhuan Liu;Zhiyuan Cao
Journal of Analysis and Testing 2017 Volume 1( Issue 2) pp:14
Publication Date(Web):14 June 2017
DOI:10.1007/s41664-017-0013-9
Electrochemiluminescence (ECL), also called electrogenerated chemiluminescence, is luminescence that is produced by chemical reactions triggered by electrochemical method. ECL imaging is a novel imaging technique, which can simultaneously provide two kinds of signals of both electrochemistry and optical image. Over the past two decades, ECL imaging has been not only a powerful tool for investigating the fundamental scientific questions such as ECL mechanisms and reaction kinetics, but also a versatile analytical technique for detection of a wide range of analytes including small molecules, DNA, proteins, and cells. In the first part of this review, we briefly describe the reaction mechanisms of ECL generation. Then the review focuses on the research progress on the ECL imaging approach. It is basically introduced from the following five aspects: (i) visualization of electroactive sites on surfaces, (ii) imaging analysis at the single-bead and single-cell levels, (iii) array bioanalysis, (iv) multi-color ECL imaging, and (v) paper chip based on ECL imaging. Finally, some perspectives and future directions in this active research area are presented.
Co-reporter:Fei Yan and Bin Su
Analytical Chemistry 2016 Volume 88(Issue 22) pp:11001
Publication Date(Web):October 24, 2016
DOI:10.1021/acs.analchem.6b02823
Antioxidants are widely found or used in food, pharmaceutical, and cosmetics industries; thus, rapid and sensitive detection of antioxidants is of great interest. The present work reports a simple and fast electrochemical method for direct analysis of antioxidants in fruit juices by modulating the permeability of mesochannels on the electrode surface. This goal was achieved by growing vertical silica mesochannel array (SMA) with a channel diameter of 2–3 nm on the indium tin oxide (ITO) electrode surface using the cylindrical micelles (CMs) as the template. As-prepared electrodes, designed as CM@SMA/ITO, are only permeable to lipophilic antioxidants, e.g., retinol, with the hydrophobic hydrocarbon cores of CMs. After excluding CMs from silica mesochannels, the ITO electrode modified with bare SMA, namely SMA/ITO, possesses a high density of silanol groups on the channel wall and thus is only permeable to hydrophilic antioxidants, such as ascorbic acid (AA). Two types of sensors allowed the selective analyses of retinol and AA in buffer solutions and demonstrated a wide linear range for retinol (1–60 μM) and AA (10–2000 μM), respectively, and a low detection limit (0.65 μM for retinol and 0.52 μM for AA). Moreover, the SMA/ITO electrode can selectively determine the concentration of AA in orange juice. The CM@SMA/ITO electrode can measure the sum activity of lipophilic antioxidants, such as retinol, α-tocopherol, and others possibly coexisting, in carrot juice. In addition, the ultrasmall mesochannels and CMs could effectively exclude the access of large substances, rendering an excellent antifouling and anti-interference ability for direct analysis of antioxidants in fruit juices without sample pretreatment.
Co-reporter:Xiao Huang, Lisiqi Xie, Xingyu Lin, and Bin Su
Analytical Chemistry 2016 Volume 88(Issue 12) pp:6563
Publication Date(Web):May 31, 2016
DOI:10.1021/acs.analchem.6b01383
Free-standing silica nanochannel membrane (SNM) with perforated channels was utilized to create arrays of nanoscale interfaces between two immiscible electrolyte solutions (nano-ITIES), at which permselective ion transfer and detection were achieved. The SNM consisted of a high density of straight nanochannels with a diameter of 2–3 nm and a length of 70 nm. The silicon wafer coated by 150 nm-thick porous silicon nitride film (p-SiNF) with pores of 5 μm-in-diameter was used to support the SNM in a form of nanochannel-on-micropore. Considering the material surface lipophilicity, the nano-ITIES array was formed at the boundary between SNM and p-SiNF, with a diffusion geometry equivalent to two back-to-back inlaid microdisc interfaces. Thus, the transfer of tetraethylammonium (TEA+) across the nano-ITIES array yielded symmetric sigmoidal current responses. In addition, because of the ultrasmall size and negatively charged surface of silica nanochannels, the nano-ITIES displayed obvious size and charge permselectivities. Transfer of ions with a size comparable with or larger than the nanochannel was sterically blocked. Also that of anions with a size smaller than the nanochannels encountered the strong electrostatic repulsion from channel walls, showing obvious dependence on the ionic strength of aqueous solution. The present approach is facile and inexpensive for building a nano-ITIES array with potential applications in ion detection and separation.
Co-reporter:Xingyu Lin, Bowen Zhang, Qian Yang, Fei Yan, Xin Hua, and Bin Su
Analytical Chemistry 2016 Volume 88(Issue 15) pp:7821
Publication Date(Web):July 14, 2016
DOI:10.1021/acs.analchem.6b01866
We report in this work the fabrication of ultrathin silica nanochannel membranes inhomogeneously modified by polydimethysiloxane (PDMS), designated as PDMS-SNM, for hydrophobicity-based molecular filtration and detection. The modification was accomplished by spatially selective evaporation of hydrophobic PDMS oligomers onto the top surface of the membrane and orifice of silica nanochannels. Thanks to this hydrophobic ultrathin layer and beneath ultrasmall channels (2–3 nm in diameter), only small hydrophobic molecules are able to transport through the PDMS-SNM, whereas hydrophilic and large ones are remarkably inhibited. We first employed this PDMS-SNM as the molecular sieving matrix for selective electrochemical detection of hydrophobic organophosphates (OPs) in milk samples without pretreatment. The PDMS-SNM modified electrode displayed an excellent analytical performance and antifouling/anti-interference ability. We also prepared the free-standing PDMS-SNM consisting of perforated channels, which could filtrate molecules based on their hydrophobicity with an excellent selectivity. As demonstrated, 2,4,6-trinitrotoluene and dopamine could be separated with a selectivity coefficient as high as 335. Moreover, because of the inhomogeneous nanochannel structure and ultrasmall thickness, a remarkably high flux of hydrophobic molecules across the PDMS-SNM was obtained, which was 3–4 orders of magnitude higher than that reported previously.
Co-reporter:Qinqin Sun, Fei Yan, Lina Yao, and Bin Su
Analytical Chemistry 2016 Volume 88(Issue 17) pp:8364
Publication Date(Web):August 15, 2016
DOI:10.1021/acs.analchem.6b02091
Direct electrochemical detection in human whole blood remains challenging due to electrode surface fouling and passivation by abundant biological substances. In this work we report that the isoporous silica-micelle membranes (designated as iSMM) can effectively function as antibiofouling layer for electrochemical detection of drug molecules in human whole blood without pretreatment. The iSMM possesses molecular sieving capacity, charge/lipophilicity selectivity, and preconcentration ability. Only small and neutral/lipophilic analytes can permeate the iSMM, be concentrated, and subsequently be detected at the underlying electrode. It is however impermeable to big sized substances and those small but charged and hydrophilic. We first investigated the molecular permeability of iSMM by electrochemical impedance spectroscopy (EIS) and then demonstrated its application in the quantitative determination of chloramphenicol (CAP) in the unprocessed human whole blood. The analytical sensitivity and long-term stability of iSMM based electrochemical sensors are apparently better than bare electrodes.
Co-reporter:Qian Yang, Xingyu Lin, and Bin Su
Analytical Chemistry 2016 Volume 88(Issue 20) pp:10252
Publication Date(Web):September 28, 2016
DOI:10.1021/acs.analchem.6b02968
An ideal molecular filtration membranes should be highly permeable and selective, thus desiring the membranes to be ultrathin, be highly porous, and consists of small and uniform pores or channels. In this work, we report the molecular filtration by free-standing ultrathin silica nanochannel membranes (SNMs) using a U-shaped cell and spectrophotometric detection, focusing on the quantitative evaluation of permeability and selectivity of SNMs. Thanks to the ultrasmall channel size, namely, ∼2–3 nm, and the negatively charged channel surface arising from the deprotonation of silanol groups, the SNM displayed excellent size and charge selectivity for molecular filtration. The selectivity coefficient for separation of small methyl viologen from large cytochrome c is as high as 273, because of the uniform pore/channel size. The charge-based filtration can be modulated by the salt concentration and solution pH, which control the overlap of radial electrical double layer and surface charge sign/density, respectively. Owing to the high relative pore density, namely, 16.7%, and the straight and vertical channel orientation, the SNM is highly permeable, displaying a molecule flux much higher than commercially available dialysis membrane and others reported previously. In addition, we demonstrated that, by biasing a small voltage across the SNM, both the flux and separation selectivity could be significantly enhanced.
Co-reporter:Yafeng Wang, Xingyu Lin, Bin Su
Electrochemistry Communications 2016 Volume 72() pp:1-4
Publication Date(Web):November 2016
DOI:10.1016/j.elecom.2016.08.016
•A facile approach for achieving redox cycling is reported.•This approach does not rely on any expensive facilities or complicated conditions.•A nanochannel membrane mediates the redox cycling between two ITO electrodes.•Vertical nanochannels allow the effective mass transport of redox probes.•Redox cycling is modulated by the electrical double layer at the channel surface.We report a simple strategy for redox cycling between 2 mm sized indium tin oxide (ITO) electrodes. The system was fabricated by putting a bare ITO electrode directly on top of another one coated with a 112 nm thick silica nanochannel membrane (SNM). When sweeping the potential of the bare ITO electrode while holding that of the SNM-coated one at a constant reduction potential, the oxidation and reduction of reversible redox probes can be cycled via the nanochannels between the two adjacent electrodes. The cycling can significantly enhance the magnitude of the electrochemical current up to 29-fold. In addition, the redox cycling can be modulated by the probe charge and the ionic strength of the solution.
Co-reporter:Fei Yan, Xingyu Lin and Bin Su
Analyst 2016 vol. 141(Issue 12) pp:3482-3495
Publication Date(Web):24 Feb 2016
DOI:10.1039/C6AN00146G
Mesoporous silica films consisting of highly ordered and vertically aligned nanochannels (abbreviated as VMSFs) have received considerable attention because of their high surface area, long-range order, thermal and mechanical stability, controllable pore size and more importantly good molecular accessibility for rapid mass transport. These characteristics are ideal for electroanalytical chemistry and separation science. In this review, we firstly present briefly the strategies for the synthesis of VMSFs on the electrode surface, mainly the electrochemically assisted self-assembly and Stöber-solution growth approaches, as well as the surface modification of channel walls with diverse terminal groups for various functionalities. In the next section, recent progress on the applications of VMSFs in electroanalytical chemistry and sensing is summarized, in terms of the spatial confinement and permselective effects (size, charge and lipophilicity selectivity of the mesochannels). We then present the preparation and application of perforated free-standing VMSFs for fast and precise molecular sieving/separation. The review ends with an outlook and perspective on the future applications of VMSFs.
Co-reporter:Lina Yao, Fei Yan and Bin Su
Analyst 2016 vol. 141(Issue 7) pp:2303-2307
Publication Date(Web):05 Feb 2016
DOI:10.1039/C5AN02439K
Halonitrobenzenes (HNBs) are a class of molecules that are highly toxic to human health and the ecological environment. Thus, effective and efficient approaches capable of monitoring and detecting HNBs are greatly desired. We report herein a simple and sensitive method for the detection of HNBs. The detection was based on the indium tin oxide (ITO) electrodes modified with a binary assembly of highly ordered surfactant micelles (OSMs) and silica mesochannels (SMs). The SMs have a diameter of 2–3 nm and a vertical orientation, which provide a hard support to stabilize soft OSMs. Moreover, each OSM consists of a hydrophobic core due to the organized assembly of surfactant hydrocarbon chains, which can selectively extract and concentrate lipophilic HNBs from aqueous media, allow their transport to the underlying ITO electrode surface and therein their detection by voltammetry. As a proof-of-concept experiment, 1-chloro-3-nitrobenzene, 1-chloro-4-nitrobenzene, 1-bromo-4-nitrobenzene and 2,4-dinitrobromobenzene were analyzed in aqueous solutions. A simple and fast detection was achieved in all cases, with a wide linear dynamic range, a high sensitivity and a low limit of detection at the ppb level. Apart from the extraction ability, the OSMs also prohibited the access of and surface contamination by unwanted substances, showing excellent anti-fouling and anti-interference power. Indeed, as we demonstrated, the sensor could be employed for direct electrochemical detection of HNBs in complex samples, such as lake water and soil dispersion, without any pre-treatment, indicating its potential usefulness in practical analysis.
Co-reporter:Wenjing Zheng, Fei Yan, Bin Su
Journal of Electroanalytical Chemistry 2016 Volume 781() pp:383-388
Publication Date(Web):15 November 2016
DOI:10.1016/j.jelechem.2016.04.017
•A binary assembly of cylindrical surfactant micelles and vertical silica mesochannels (CSM@VSM)•Direct electrochemical determination of CAP using CSM@VSM film in milk and honey without sample pre-treatment•Size selective extraction and concentration of CAP by CSMs via the hydrophobic interaction•The anti-fouling and anti-interference ability due to inert and permselective ultrasmall VSMsChloramphenicol (CAP), an antibiotic, is closely related to the food safety, ecological environment and human health. It is therefore of great importance to develop simple and rapid methods for CAP determination. We report in this work the utilization of indium tin oxide (ITO) electrodes modified with a binary assembly of vertical silica mesochannels (VSMs) and cylindrical surfactant micelles (CSMs) for the electrochemical detection of CAP. Each hard VSM of 2–3 nm in diameter supports and confines a soft CSM of cetyltrimethylammonium bromide (CTAB), which has a hydrocarbon core capable of extracting and concentrating lipophilic organic analytes from sample solutions. So the CSM@VSM modified electrode exhibited an analytical performance for CAP apparently superior to bare and VSM modified electrodes. Under optimized conditions, two linear dynamic concentration ranges were obtained for CAP determination using differential pulse voltammetry, namely 0.1 to 3.6 ppm and 3.6 to 15.0 ppm, as well as a low limit of detection at 40 ppb. Moreover, thanks to the ultrasmall size of silica channels and the lipophilic microenvironment of micelle cores, the CSM@VSM film displayed an excellent hydrophobic selectivity and anti-fouling ability by preventing unwanted substances from accessing to and contaminating the underlying electrode surface. Therefore, reliable results were obtained for direct electrochemical determination of CAP in real samples, such as milk and honey, without pre-treatment.
Co-reporter:Weiliang Guo;Xingyu Lin;Fei Yan ; Bin Su
ChemElectroChem 2016 Volume 3( Issue 3) pp:480-486
Publication Date(Web):
DOI:10.1002/celc.201500329
Abstract
This paper describes a miniaturized bipolar electrode (BPE) sensor that is constructed with an indium tin oxide (ITO) microband and a slice of poly(dimethylsioxane) (PDMS). The ITO microband modified by vertically ordered silica mesochannels (SMCs) functions as the BPE. Owing to the uniform pore size of ≈2–3 nm in diameter and negatively charged surface, the SMCs can significantly accelerate the mass transport of positively charged species via strong electrostatic interactions. Thus, an increase of more than two orders of magnitude in sensitivity for tri-n-propylamine (TPrA) analysis was achieved for the electrochemluminescence (ECL) of tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)32+) at a relatively low concentration (10 μm). Moreover, the SMC film with ultrasmall channels can effectively serve as an antifouling layer of the underlying ITO electrode to prevent the access of undesired large molecules, allowing the electrochemical detection in real complex media, such as atropine and l-proline in human blood serum.
Co-reporter:Fei Yan, Wenjing Zheng, Lina Yao and Bin Su
Chemical Communications 2015 vol. 51(Issue 100) pp:17736-17739
Publication Date(Web):16 Oct 2015
DOI:10.1039/C5CC08425C
Herein we report a simple and cost-effective method for the direct electrochemical detection of redox-active small organic analytes in complex media, such as soil dispersions, human serum and milk, without sample pre-treatment using an indium tin oxide (ITO) electrode modified with permselective membranes consisting of vertically ordered surfactant micelles and silica mesochannels (OSM@SM). The OSM@SM/ITO electrode displayed excellent anti-interference and anti-fouling ability.
Co-reporter:Fei Yan, Yayun He, Longhua Ding, and Bin Su
Analytical Chemistry 2015 Volume 87(Issue 8) pp:4436
Publication Date(Web):March 27, 2015
DOI:10.1021/acs.analchem.5b00433
The rapid and sensitive detection of nitroaromatic compounds is of great significance for human health, the environment, and public security. The present work reports on the extraction and electrochemical analysis of trace nitroaromatic compounds, such as explosives and organophosphate pesticides (OPs), using the indium tin oxide (ITO) electrodes modified with a highly ordered and aligned binary assembly of silica mesochannels and micelles (BASMM). With a pore diameter of ca. 2–3 nm, silica mesochannels (SMs) perpendicularly oriented to the ITO electrode surface can provide hard and robust supports to confine the soft cylindrical micelles formed by the aggregation of cationic surfactants, namely, cetyltrimethylammonium bromide (CTAB). Due to the organized self-assembly of hydrocarbon tails of CTAB surfactants, each micelle has a hydrophobic core, which acts as an excellent adsorbent for rapid extraction and preconcentration of trace nitroaromatic compounds from aqueous solutions via the hydrophobic effect. Furthermore, the cylindrical micelles are directly in contact with the underlying electrode surface, to which extracted compounds can freely diffuse and then be reduced therein, thus allowing their determination by means of voltammetry. Using the BASMM/ITO sensor, electrochemical analysis of trace nitroaromatic explosives, including 2,4,6-trinitrotoluene (TNT), 2,4,6-trinitrophenol, 2,6-dinitrotoluene, 3-nitrophenol, and nitrobenzene, and OPs, such as paraoxon, methyl parathion, and fenitrothion, was achieved with a fast response, wide linear range, high sensitivity, and low detection limit at the ppb level. TNT and paraoxon in real apple, tea, and water samples were also determined. By combining the heterogeneous extraction and determination in one ordered binary nanostructure, the BASMM sensor provides a very simple, rapid, and cost-effective way for analysis of nitroaromatic compounds and can be extended to a wide range of lipophilic yet redox-active analytes.
Co-reporter:Qiaohong Wang, Qian Yang, Bin Su
Electrochimica Acta 2015 Volume 161() pp:290-296
Publication Date(Web):10 April 2015
DOI:10.1016/j.electacta.2015.02.104
•Vertical silica mesochannels (SMCs) were prepared on the indium tin oxide (ITO) electrode.•Microperoxidase-11 (MP-11) monomers were adsorbed to SMCs via electrostatic interaction.•The electron transfer reaction was studied by voltammetry.Microperoxidase-11 (MP-11) is an excellent model for hemoproteins such as cytochrome c. In this work, we report the adsorption of MP-11 onto silica mesochannels (SMCs) vertically attached to the indium tin oxide (ITO) electrode surface via the electrostatic attraction. Given the diameter of SMCs (2 ∼ 3 nm) is comparable to the molecular dimension of MP-11 (1.1 × 1.7 × 3.3 nm), only its monomeric form was selectively adsorbed by SMCs, as revealed by the UV-visible spectroscopy measurements. The cyclic voltammgram of adsorbed MP-11 molecules showed that the peak current was linearly dependent on the scan rate, suggesting the occurrence of a surface controlled process. And thus estimated surface coverage was indicative of adsorption of multiple MP-11 molecules in a SMC. We inferred that the electron transfer reaction is kinetically limited by the electron communication between MP-11 molecules adjacent to the electrode and the electrode. The rate constant was estimated to be 8.3 s−1.
Co-reporter:Longhua Ding, Bin Su
Journal of Electroanalytical Chemistry 2015 Volume 736() pp:83-87
Publication Date(Web):1 January 2015
DOI:10.1016/j.jelechem.2014.11.001
•We report an approach to prepare platinum nanoparticle and polyaniline composite.•The composite was confined in silica mesochannels vertically attached to electrode.•The nanocomposite film is used for non-enzymatic hydrogen peroxide sensing.We demonstrated a facile method for supporting platinum nanoparticles (PtNPs) on polyaniline (PANI)/mesoporous silica film (MSF). The MSF with mesochannels perpendicular to the underlying electrode surface can confine the electrodeposition of PANI and improve the mechanical strength of PANI. The secondary amines and tertiary imines on the PANI backbone can readily complex with PtCl62− ions, which can be further reduced to generate Pt nanoparticles (NPs). The obtained PtNPs@PANI/MSF hybrid material was characterized by transmission electron microscopy and energy dispersive X-ray spectroscopic analysis. It also exhibited a good electrocatalytic activity toward oxidation of H2O2 and can be used to detect H2O2 with a high sensitivity (50 μΑ mM−1) in a wide concentration range (1.0–2000 μM).
Co-reporter:Longhua Ding and Bin Su
RSC Advances 2015 vol. 5(Issue 81) pp:65922-65926
Publication Date(Web):24 Jul 2015
DOI:10.1039/C5RA13482J
We report a facile electrochemistry assisted sol–gel approach for the preparation of mesoporous silica nanoparticles (MSNs) at the gram scale on common conductive substrates, such as the stainless steel surface. The formation of MSNs was triggered by electrochemical generation of hydroxide at the substrate/solution interface, which induced the self-assembly of surfactant micelles and meanwhile catalysed the polycondensation of silica precursors. The as-prepared MSNs were characterized in detail by several instrumental analysis techniques, revealing the obtained MSNs have a uniform pore size of about 2.4 nm and a high surface area of about 1164 m2 g−1. We believe that this approach can provide a simple, fast and low-cost way to produce MSNs and may be potentially useful for the large-scale industrial production.
Co-reporter:Qinqin Sun, Wanzhen Li, Bin Su
Journal of Electroanalytical Chemistry 2015 740() pp: 21-27
Publication Date(Web):
DOI:10.1016/j.jelechem.2014.12.038
Co-reporter:Yaofang Xuan
The Journal of Physical Chemistry C 2015 Volume 119(Issue 21) pp:11685-11693
Publication Date(Web):May 4, 2015
DOI:10.1021/acs.jpcc.5b02131
An investigation of oxygen reduction reaction (ORR) catalyzed by microperoxidase-11 (MP-11) at the polarized water/1,2-dichloroethane (DCE) interface is reported. MP-11 contains a heme group covalently bonded to an undecapeptide chain via two thioether bonds of cysteine residues, as in cytochrome c oxidases (CcOs), and has been widely studied as a biomimetic model of CcOs. Herein we demonstrated that MP-11 can adsorb at the water/DCE interface and catalyze the O2 reduction by lipophilic electron donors, namely tetrathiafulvalene (TTF) and 1,1′-dimethylferrocene (DFc). The overall catalytic ORR corresponds to a proton coupled electron transfer (PCET) reaction and is kinetically controlled by the heterogeneous conversion of MP-11 from ferric (FeIII-MP-11) to ferrous state (FeII-MP-11). Given that a significant amount of H2O2 was produced for both electron donors, it indicates that MP-11 has a remarkable impact on the ORR pathway and that MP-11, similar to other mononuclear macrocyclic compounds, cannot selectively catalyze the 4e–/4H+ reduction of O2 to H2O. The results also suggest that one should carefully considers the role of Cu site in CcOs and the reaction environment to understand respiratory ORR and to develop more selective catalysts for practical applications (e.g., fuel cells).
Co-reporter:Xingyu Lin, Qian Yang, Longhua Ding, and Bin Su
ACS Nano 2015 Volume 9(Issue 11) pp:11266
Publication Date(Web):October 12, 2015
DOI:10.1021/acsnano.5b04887
Membranes with the ability of molecular/ionic separation offer potential in many processes ranging from molecular purification/sensing, to nanofluidics and to mimicking biological membranes. In this work, we report the preparation of a perforative free-standing ultrathin silica membrane consisting of straight and parallel nanochannels with a uniform size (∼2.3 nm) for precise and fast molecular separation. Due to its small and uniform channel size, the membrane exhibits a precise selectivity toward molecules based on size and charge, which can be tuned by ionic strength, pH or surface modification. Furthermore, the ultrasmall thickness (10–120 nm), vertically aligned channels, and high porosity (4.0 × 1012 pores cm–2) give rise to a significantly high molecular transport rate. In addition, the membrane also displays excellent stability and can be consecutively reused for a month after washing or calcination. More importantly, the membrane fabrication is convenient, inexpensive, and does not rely on sophisticated facilities or conditions, providing potential applications in both separation science and micro/nanofluidic chip technologies.Keywords: ion transport; molecular separation; nanochannel; silica; ultrathin membrane;
Co-reporter:Yayun He;Longhua Ding
Science China Chemistry 2015 Volume 58( Issue 10) pp:1593-1599
Publication Date(Web):2015 October
DOI:10.1007/s11426-015-5365-2
Silica mesochannels (SMCs) vertically and regularly oriented to the surface of indium tin oxide (ITO) electrodes were prepared and utilized for preconcentration and detection of methylene blue (MB) in aqueous solution. The positively charged MB can be adsorbed to the SMCs by following the pseudo-first-order kinetic model. The negative value of ΔG=−34.73 kJ/mol derived from the Langmuir adsorption isotherm indicated the thermodynamic feasibility of the adsorption and the spontaneous nature of the process. Moreover, the adsorbed MB can undergo an electrochemical reaction on the ITO electrode at a suitable potential and the resulting electrical current can be utilized to quantify the MB in aqueous solution. A good analytical performance for MB with a linear range from 10 nmol/L to 1.0 μmol/L and a detection limit at the nmol/L level was obtained. We believe that such a platform consisting of SMCs perpendicularly tethered to the underlying electrode surface simultaneously allows enrichment and electrochemical detection and can be extended for the detection of various charged dyes, as well as many other charged species.
Co-reporter:Linru Xu;Congzhe Zhang;Yayun He
Science China Chemistry 2015 Volume 58( Issue 7) pp:1090-1096
Publication Date(Web):2015 July
DOI:10.1007/s11426-014-5294-5
Fingerprints have been used as an indispensable tool for personal identification in forensic investigations since the late 19th century. At present, fingerprinting technology has moved away from its forensic roots and is incorporating a broader scientific range, e.g., material science, spectroscopy and spectral analysis, and even in vitro diagnosis. After a brief introduction to latent fingerprints, this mini-review presents the pioneering progresses of fingerprinting technologies including (i) material and electrochemical techniques, and (ii) spectral and spectroscopy imaging techniques and immunological techniques capable of both the visualization of a fingerprint and the detection of chemicals present in it. Finally, perspectives on this rapidly developing field are discussed.
Co-reporter:Linru Xu, Zhenyu Zhou, Congzhe Zhang, Yayun He and Bin Su
Chemical Communications 2014 vol. 50(Issue 65) pp:9097-9100
Publication Date(Web):20 Jun 2014
DOI:10.1039/C4CC03466J
We present the combination of electrochemiluminescence imaging with enzyme immunoassay for the highly sensitive detection of protein/polypeptide residues in latent fingermarks. This technique provides an effective method for fingermark detection that enables both identification of an individual and recognition of the secretions in the human perspiration.
Co-reporter:Linru Xu, Yan Li, Shuhong Li, Rongrong Hu, Anjun Qin, Ben Zhong Tang and Bin Su
Analyst 2014 vol. 139(Issue 10) pp:2332-2335
Publication Date(Web):27 Jan 2014
DOI:10.1039/C3AN02367B
A graphical abstract is available for this content
Co-reporter:Zhenyu Zhou, Linru Xu, Suozhu Wu and Bin Su
Analyst 2014 vol. 139(Issue 19) pp:4934-4939
Publication Date(Web):20 Jun 2014
DOI:10.1039/C4AN00687A
Electrochemiluminescence (ECL) imaging provides a superior approach to achieve array detection because of its ability for ultrasensitive multiplex analysis. In this paper, we reported a novel ECL imaging biosensor array modified with an enzyme/carbon nanotubes/chitosan composite film for the determination of glucose, choline and lactate. The biosensor array was constructed by integrating a patterned indium tin oxide (ITO) glass plate with six perforated poly(dimethylsiloxane) (PDMS) covers. ECL is generated by the electrochemical reaction between luminol and hydrogen peroxide that is produced by the enzyme catalysed oxidation of different substrates with molecular oxygen, and ECL images were captured by a charge-coupled device (CCD) camera. The separated electrochemical micro-cells enabled simultaneous assay of six samples at different concentrations. From the established calibration curves, the detection limits were 14 μM for glucose, 40 μM for lactate and 97 μM for choline, respectively. Moreover, multicomponent assays and cross reactivity were also studied, both of which were satisfied for the analysis. This biosensing platform based on ECL imaging shows many distinct advantages, including miniaturization, low cost, and multi-functionalization. We believe that this novel ECL imaging biosensor platform will have potential applications in clinical diagnostics, medicine and food inspection.
Co-reporter:Wanzhen Li, Longhua Ding, Qiaohong Wang and Bin Su
Analyst 2014 vol. 139(Issue 16) pp:3926-3931
Publication Date(Web):19 May 2014
DOI:10.1039/C4AN00605D
A thin film consisting of highly ordered and vertically oriented silica mesochannels (SMCs) was prepared on the indium tin oxide (ITO) coated glass electrode surface by chronopotentiometry. The mesochannel has a uniform pore size of 2–3 nm in diameter and a positively charged surface due to grafted ammonium groups. The electrostatic and steric effects resulted from control of the surface charge and the ionic buffer concentration make the SMCs permselective, favoring the mass transport of oppositely charged species and repelling that of similarly charged ones. By using differential pulse voltammetry (DPV), the SMCs with this charge selectivity can be employed for permselective detection of ascorbic acid (AA) and dopamine (DA) that are oppositely charged compounds. The obtained linear detection range was 49–2651 μM for AA and 20–226 μM for DA, respectively. AA and DA in real samples were also determined by the SMC film modified electrode.
Co-reporter:Yayun He;Linru Xu;Yu Zhu;Qianhui Wei; Meiqin Zhang; Bin Su
Angewandte Chemie 2014 Volume 126( Issue 46) pp:12817-12820
Publication Date(Web):
DOI:10.1002/ange.201404416
Abstract
A simple method termed immunological multimetal deposition (iMMD) was developed for rapid visualization of sweat fingerprints with bare eyes, by combining the conventional MMD with the immunoassay technique. In this approach, antibody-conjugated gold nanoparticles (AuNPs) were used to specifically interact with the corresponding antigens in the fingerprint residue. The AuNPs serve as the nucleation sites for autometallographic deposition of silver particles from the silver staining solution, generating a dark ridge pattern for visual detection. Using fingerprints inked with human immunoglobulin G (hIgG), we obtained the optimal formulation of iMMD, which was then successfully applied to visualize sweat fingerprints through the detection of two secreted polypeptides, epidermal growth factor and lysozyme. In comparison with the conventional MMD, iMMD is faster and can provide additional information than just identification. Moreover, iMMD is facile and does not need expensive instruments.
Co-reporter:Suozhu Wu, Zhenyu Zhou, Linru Xu, Bin Su, Qun Fang
Biosensors and Bioelectronics 2014 Volume 53() pp:148-153
Publication Date(Web):15 March 2014
DOI:10.1016/j.bios.2013.09.042
•A microdroplet sensor was constructed with a closed bipolar cell.•Bipolar electrochemistry and electrochemiluminescence imaging was used for sensing.•This sensor can be used for both single-point and array detections.•Amperometric detection was easily realized by the microdroplet sensor.•Multiphase analysis was facilely realized using the proposed sensor.Here we develop a microdroplet sensor based on bipolar electrochemistry and electrochemiluminescence (ECL) imaging. The sensor was constructed with a closed bipolar cell on a hybrid poly(dimethylsioxane) (PDMS)-indium tin oxide (ITO) glass microchip. The ITO microband functions as the bipolar electrode and its two poles are placed in two spatially separate micro-reservoirs predrilled on the PDMS cover. After loading microliter-sized liquid droplets of tris(2,2′-bipyridyl) ruthenium (II)/2-(dibutylamino) ethanol (Ru(bpy)32+/DBAE) and the analyte to the micro-reservoirs, an appropriate external voltage imposed on the driving electrodes could induce the oxidation of Ru(bpy)32+/DBAE and simultaneous reduction of the analyte at the anodic and cathodic poles, respectively. ECL images generated by Ru(bpy)32+/DBAE oxidation at the anodic pole and the electrical current flowing through the bipolar electrode can be recorded for quantitative analyte detection. Several types of quinones were selected as model analytes to demonstrate the sensor performance. Furthermore, the cathodic pole of bipolar electrode can be modified with (3-aminopropyl)triethoxysilane–gold nanoparticles–horseradish peroxidase composites for hydrogen peroxide detection. This microdroplet sensor with a closed bipolar cell can avoid the interference and cross-contamination between analyte solutions and ECL reporting reagents. It is also well adapted for chemical analysis in the incompatible system, e.g., detection of organic compounds insoluble in water by aqueous ECL generation. Moreover, this microdroplet sensor has advantages of simple structure, high sensitivity, fast response and wide dynamic response, providing great promise for chemical and biological analysis.
Co-reporter:Yayun He;Linru Xu;Yu Zhu;Qianhui Wei; Meiqin Zhang; Bin Su
Angewandte Chemie International Edition 2014 Volume 53( Issue 46) pp:12609-12612
Publication Date(Web):
DOI:10.1002/anie.201404416
Abstract
A simple method termed immunological multimetal deposition (iMMD) was developed for rapid visualization of sweat fingerprints with bare eyes, by combining the conventional MMD with the immunoassay technique. In this approach, antibody-conjugated gold nanoparticles (AuNPs) were used to specifically interact with the corresponding antigens in the fingerprint residue. The AuNPs serve as the nucleation sites for autometallographic deposition of silver particles from the silver staining solution, generating a dark ridge pattern for visual detection. Using fingerprints inked with human immunoglobulin G (hIgG), we obtained the optimal formulation of iMMD, which was then successfully applied to visualize sweat fingerprints through the detection of two secreted polypeptides, epidermal growth factor and lysozyme. In comparison with the conventional MMD, iMMD is faster and can provide additional information than just identification. Moreover, iMMD is facile and does not need expensive instruments.
Co-reporter:Longhua Ding;Wanzhen Li;Qiaohong Wang;Qinqin Sun;Yayun He ; Bin Su
Chemistry - A European Journal 2014 Volume 20( Issue 7) pp:1829-1833
Publication Date(Web):
DOI:10.1002/chem.201303807
Abstract
A mesoporous silica film (MSF) with vertically oriented mesochannels on a conductive substrate serves as a hard-template for electrodeposition of polyaniline (PANI). The PANI nanostructures thus prepared are orderly confined in silica mesochannels, eventually producing a robust hybrid film. The film displays a good electrocatalytic activity toward oxidation of ascorbic acid, and can be used for potentiometric pH sensing with a Nernstian response.
Co-reporter:Longhua Ding;Wanzhen Li;Qinqin Sun;Yayun He ; Bin Su
Chemistry - A European Journal 2014 Volume 20( Issue 40) pp:12777-12780
Publication Date(Web):
DOI:10.1002/chem.201403426
Abstract
A facile method of confining gold nanoparticles (AuNPs) in silica nanochannels aligned perpendicularly to an underlying electrode surface is reported. The nanochannel surface carrying a layer of (3-aminopropyl)triethoxy silane (APTS) displays a strong electrostatic interaction with AuCl4−, eventually resulting in the confinement of AuNPs inside the nanochannels after chemical reduction. As-prepared AuNPs in APTS-modified mesoporous silica film (APTS-MSF) are highly dispersed with a narrow size distribution. Furthermore, these AuNPs are free of protecting ligands and exhibit a good electrochemical catalytic activity toward the oxidation of ascorbic acid.
Co-reporter:Wanzhen Li, Bin Su
Electrochemistry Communications 2013 Volume 33() pp:27-30
Publication Date(Web):August 2013
DOI:10.1016/j.elecom.2013.04.008
•We report the dependence of nanoparticle film charging on the counterion size.•The monolayer film charging occurs with small counterions but not big ones.•The dependence on the counterion size is related to the counterion proximity.•Monolayer film charging is coupled by formation of ion pairs with counterion.Herein we report the nontrivial effect of counterion size on the electrochemical charging of gold nanoparticle (or called MPC) monolayer films in aqueous electrolyte solutions. The electrochemical charging response was observed with relatively small counterions (e.g., BF4−, ClO4− and PF6−) but not large ones like bis(trifluoromethylsulfonyl)amide (Tf2N−), tetrakis(pentafluorophenyl)borate (TB−) or bis(triphenylphosphoranylidene) (BA+). This effect was explained by the proximity of counterions to the MPC surface, which determines whether the electronic charges on MPCs can be effectively compensated by formation of ion pairs. Only small counterions are permitted to approach the MPC surface by permeating the alkanethiolate layer to achieve a sufficient charge compensation. In contrast, big ions are sterically excluded and thus disfavor the electrochemical charging. This finding helps in further understanding the ion-coupled electrochemical charging mechanism of nanoparticle films.
Co-reporter:Yan Li, Linru Xu, Yayun He, Bin Su
Electrochemistry Communications 2013 Volume 33() pp:92-95
Publication Date(Web):August 2013
DOI:10.1016/j.elecom.2013.04.033
•Visualization of latent fingerprints can be enhanced by ECL of rubrene.•Spatially controlling ECL generation defines two imaging modes.•Negative imaging mode is pretty simple and has insignificant destruction.•Preferentially adsorption of rubrene aggregates allows the positive ECL imaging.We report how electrochemiluminescence (ECL) of rubrene can be utilized for enhancing the visualization of latent fingerprints in two different modes. The enhancement arises from the spatially selective ECL generation either from the substrate surface uncovered by the fingerprint or the fingerprint itself, designated negative or positive imaging mode, respectively. The negative mode is performed directly in an electrolyte solution containing rubrene and co-reactant. Given that organic residues in the fingerprint deposit make the underlying surface electrochemically inert or less active, ECL reaction occurs only on the surface untouched by the fingertip, generating a negative impression with a dark ridge pattern against the illuminated background. The positive imaging mode is based on the preferential adsorption of rubrene aggregates to the ridge materials via physical attraction; then the fingerprint can glow via ECL reaction in a solution containing co-reactant under an appropriate applied potential.
Co-reporter:Linru Xu, Yan Li, Yayun He and Bin Su
Analyst 2013 vol. 138(Issue 8) pp:2357-2362
Publication Date(Web):19 Feb 2013
DOI:10.1039/C3AN00110E
Visualization and detection of latent fingerprints (LFPs) on metal surfaces are of highly practical importance, e.g., in identifying gun cartridges. We report herein the visualization of LFPs on stainless steel surfaces by electrochemiluminescence (ECL). Since organic residues, such as fatty acids, in the fingerprint deposit make the underlying surface electrochemically inert or less active, an ECL reaction occurs only on the metal portions untouched by the fingertip, hence generating a negative image of the fingerprint. The popular ECL reaction solution, consisting of ruthenium(II) tris(2,2′-bipyridyl) and tri-n-propylamine, was used for this imaging purpose. Factors, including the applied potential and the concentration of ECL luminophore, as well as the stability of ECL negative images, were investigated to achieve a satisfactory visualization enhancement. This imaging approach is simple, rapid, non-invasive, and no pre-treatment either on the background or on the fingerprint itself is needed. It constitutes a powerful tool for visualizing LFPs on metal surfaces. This method was also demonstrated to be suitable for enhancing LFPs collected from various surfaces.
Co-reporter:Suozhu Wu, Bin Su
Journal of Electroanalytical Chemistry 2013 Volume 694() pp:12-16
Publication Date(Web):1 April 2013
DOI:10.1016/j.jelechem.2013.01.018
Herein we describe a simple approach for fabrication of microring electrodes by electroless plating a thin layer of gold on polycarbonate (PC) rods. First, the PC rod was exposed to UV light to generate carboxyl groups on the surface. After amination of the surface carboxyl groups by ethylenediamine, the rod was sequentially immersed in HAuCl4 and NaBH4 solutions to form a layer of gold nanoparticles. These gold nanoparticles then functioned as the catalytically active centers for electroless plating thin gold film on the PC rod surface. Finally, the rod surface was thoroughly covered by an insulating glue and fresh microring surface could be obtained easily by laterally cutting with a knife. The electrochemical behavior of thus prepared microring electrodes were characterized by cyclic voltammetry in hydroxymethylferrocene and H2SO4. The whole fabrication process is simple and economic, which can be carried out in ordinary laboratories. In addition, the results of electrocatalytic oxygen reduction demonstrated that the proposed microelectrode could be used as an alternative electrode materials for electrocatalysis and electroanalysis.Highlights► A novel approach was proposed for fabrication of microring electrodes. ► This approach was based on electroless plating technique. ► The proposed approach was simple and economic. ► The prepared microring electrodes could be renewably simply by cutting with a knife.
Co-reporter:Xianghong Liu, Suozhu Wu, Bin Su
Journal of Electroanalytical Chemistry 2013 Volume 709() pp:26-30
Publication Date(Web):15 November 2013
DOI:10.1016/j.jelechem.2013.09.024
•O2 reduction by TTF can be catalyzed by H2TPP.•TTF can reduce O2 to H2O alone and to H2O2 in the presence of H2TPP.•Polarization activation of O2 by H4TPP2+ is further proved.In this work we report the catalytic effect of 5,10,15,20-tetraphenylporphyrin (H2TPP) on the reduction of oxygen (O2) by a weak electron donor, namely tetrathiafulvalene (TTF), at the polarized water/1,2-dichloroethane (DCE) interface. TTF alone, as reported previously, can reduce O2 slowly via a four-electron transfer pathway to produce water. Herein we show that H2TPP can catalyze the reduction of O2 by TTF to form hydrogen peroxide (H2O2) at the water/DCE interface, which was investigated by voltammetry and biphasic shake-flask experiments. The overall process was found to be essentially a proton-coupled electron transfer reaction. And the results also proved that the catalytic activity of H2TPP toward O2 reduction under acid condition arises from the polarization activation of O2 by H2TPP diacid, namely H4TPP2+.
Co-reporter:Wanzhen Li;Qinqin Sun
Journal of Solid State Electrochemistry 2013 Volume 17( Issue 9) pp:2429-2435
Publication Date(Web):2013 September
DOI:10.1007/s10008-013-2121-4
Reactivity of halide anion (Cl−) with monolayer-protected gold nanoclusters (MPCs) of 1.8 nm in diameter has been studied. Typically, thin films of MPCs were prepared on an electrode surface and immersed in aqueous solutions containing Cl−. It was observed that Cl− inevitably resulted in the destruction of electrochemical charging of MPC films, which was studied and analyzed in details by cyclic voltammetry, electrochemical quartz crystal microbalance, and X-ray photoelectron spectroscopy measurements. The destruction is most likely due to the strong affinity of Cl− for the surface of MPCs, leading to a significant variation of the surface structure and thereby quenching the electrochemical charging property.
Co-reporter:Yan Li, Linru Xu and Bin Su
Chemical Communications 2012 vol. 48(Issue 34) pp:4109-4111
Publication Date(Web):05 Mar 2012
DOI:10.1039/C2CC30553D
The aggregation-induced emission of tetraphenylethene was explored for enhancing the visualization of latent fingerprints on wet non-porous surfaces.
Co-reporter:Wanzhen Li, Bin Su
Electrochemistry Communications 2012 Volume 22() pp:8-11
Publication Date(Web):August 2012
DOI:10.1016/j.elecom.2012.05.013
Reductive electron transfer dynamics in the multilayer film of alkanethiolate monolayer protected clusters (so-called MPCs) contacted with an aqueous electrolyte was studied. As determined by potential step chronoamperometry, electrons are transported within the film phenomenologically via the diffusion-like hopping (self-exchange) between the localized MPC sites with an average first order rate constant of 104 s− 1. This value is comparable with those for the similar kind of films immersed in organic electrolytes but much smaller than those for the all-solid or dry films. It thus reveals that the solvent swelling presents negligible effect on the electron hopping dynamics and that the electron transfer is most likely limited by the diffusive redistribution of the counterions in order to keep the local electroneutrality.Highlights► Reductive electron transfer dynamics in gold nanocluster films contacted with aqueous electrolytes was studied; ► Electron hopping inside gold nanocluster films is diffusion-like and limited by the redistribution of counterions; ► Solvent swelling has negligible effect on the electron hopping dynamics;
Co-reporter:Yan Li;Suozhu Wu ;Dr. Bin Su
Chemistry - A European Journal 2012 Volume 18( Issue 24) pp:7372-7376
Publication Date(Web):
DOI:10.1002/chem.201200191
Co-reporter:Suozhu Wu ;Dr. Bin Su
Chemistry - A European Journal 2012 Volume 18( Issue 11) pp:3169-3173
Publication Date(Web):
DOI:10.1002/chem.201103526
Co-reporter:Linru Xu;Yan Li;Suozhu Wu;Xianghong Liu ;Dr. Bin Su
Angewandte Chemie International Edition 2012 Volume 51( Issue 32) pp:8068-8072
Publication Date(Web):
DOI:10.1002/anie.201203815
Co-reporter:Linru Xu;Yan Li;Suozhu Wu;Xianghong Liu ;Dr. Bin Su
Angewandte Chemie 2012 Volume 124( Issue 32) pp:8192-8196
Publication Date(Web):
DOI:10.1002/ange.201203815
Co-reporter:Suozhu Wu, Yunxia Zhang, Hong Shen, Bin Su and Qun Fang
Chemical Communications 2011 vol. 47(Issue 20) pp:5723-5725
Publication Date(Web):18 Apr 2011
DOI:10.1039/C0CC05815G
With a microfluidic droplet-based liquid/liquid extraction setup, we demonstrate that the extraction of an ionic analyte from complex matrices can be modulated by the interfacial Galvani potential difference and the extraction equilibrium follows the classical Nernst equation.
Co-reporter:Wanzhen Li, Dan Wang, Qinqin Sun, Bin Su
Electrochemistry Communications 2011 Volume 13(Issue 8) pp:875-878
Publication Date(Web):August 2011
DOI:10.1016/j.elecom.2011.05.026
We herein investigated the counterion-dependent redox charging properties of gold nanocluster films in polar organic solvents. They were found to be in between those demonstrated in polar aqueous and weakly polar/nonpolar organic media, typically characteristic of a significant voltage separation between the first oxidation and reduction dependent on the lipophilicity of electrolyte counterions. The overall process was proposed to be an ion transfer coupled electron transfer reaction, which was thermodynamically limited by the counterion migration at the film/solution interface and kinetically by the diffusion-like electron hopping among MPCs within the film. These data are helpful in understanding why in previous works the counterion-dependent redox charging is evident only in highly polar aqueous media but not in weakly polar or nonpolar organic solvents.Research highlights► Ion-dependent, quantised redox charging behavior of gold nanocluster thin films in polar organic solvents. ► Diffusion-like electron hopping in nancluster thin films bathed in polar organic electrolytes. ► Solvent role in the nanocluster quantised charging.
Co-reporter:Wanzhen Li, Dan Wang, Bin Su
Electrochemistry Communications 2011 Volume 13(Issue 6) pp:631-633
Publication Date(Web):June 2011
DOI:10.1016/j.elecom.2011.03.031
Multilayer films consisting of monolayer-protected gold nanoclusters (MPCs) coated on electrode surfaces and immersed in aqueous media were investigated to elucidate the suppression of the reductive charging. On the use of water-soluble electrolytes featuring a lipophilic cation, discrete reductive charging of MPC films was unambiguously observed. It was proved to be tightly concomitant with the cation transfer at the film/solution interface by the cation concentration dependence and electrochemical quartz crystal microbalance measurements. From this study, it was rationalized that the inadequate lipophilic cations used in previous works accounted for the suppression of reductive charging current.Research highlights► Reductive charging of MPC thin films in aqueous media. ► Rationalization of the suppression of reductive charging current. ► Cation transfer coupled reductive charging.
Co-reporter:Suozhu Wu, Bin Su
Journal of Electroanalytical Chemistry 2011 Volume 656(1–2) pp:237-242
Publication Date(Web):15 June 2011
DOI:10.1016/j.jelechem.2010.11.004
The transfer of alkylammonium cations across the water/2-nitrophenyl octyl ether (NPOE) interface was studied at the three-phase junctions supported by a carbon ink screen-printed electrode (SPE) using cyclic and square-wave voltammetry. A microliter droplet of NPOE containing 7,7′,8,8′-tetracyanoquinodimethane (TCNQ) was immobilized on the surface of the SPE and was immersed in aqueous solutions containing various alkylammonium salts. A plot of the half-wave transfer potential versus the logarithm of the cation concentration exhibits a close to Nernst slope. Moreover, a plot of the half-wave transfer potentials against the formal transfer potentials of alkylammonium cations yielded a slope close to unity. All these experimental facts suggest that the reduction of TCNQ at the SPE/NPOE interface is accompanied by a simultaneous cation transfer across the NPOE/water interface to preserve the electroneutrality of the organic microdroplet, namely the overall process corresponds to a cation-coupled electron transfer reaction. Finally, this approach allowed measuring the formal transfer potential of highly lipophilic cation, such as bis(triphenylphosphoranylidene)ammonium.
Co-reporter:Jiandong Feng, Weijie Zhao, Bin Su, Jianmin Wu
Biosensors and Bioelectronics 2011 30(1) pp: 21-27
Publication Date(Web):
DOI:10.1016/j.bios.2011.08.021
Co-reporter:Min Zhou, Shiyu Gan, Lijie Zhong, Bin Su, and Li Niu
Analytical Chemistry 2010 Volume 82(Issue 18) pp:7857
Publication Date(Web):August 26, 2010
DOI:10.1021/ac102010b
Cyclic voltammetry and square wave voltammetry have been used to investigate the transfer of highly hydrophilic ions, including anions and cations, by a simple two polarized interfaces setup. The expression of apparent half-wave potential has been established detailedly by virtue of theory of sampled-current voltammetry involving semi-infinite linear diffusion, which indicates that the property of coupled ion transfer reaction has an effect on the position of the voltammogram on the potential scale. Since the data obtained agree well with literature values, it seems convincing to determine the transfer energies of those highly hydrophlic ions which are very important and have not been reported yet. Then it has been demonstrated as a novel way in combination with sensitive and fast square wave voltammetry for determining the transfer Gibbs energy of complex ions such as miscellaneous inorganic ions.
Co-reporter:Wanzhen Li
The Journal of Physical Chemistry C 2010 Volume 114(Issue 42) pp:18103-18108
Publication Date(Web):October 1, 2010
DOI:10.1021/jp1066764
Thin films consisting of alkanethiolate protected gold nanoparticles (MPCs) immersed in room temperature ionic liquids (ILs) were investigated by electrochemistry. The anion-dependent oxidative charging of MPC films was observed in imidazolium based ILs, which is similar to that of anion-rectified/limited oxidative charging previously observed in aqueous media. The absence of reductive charging in imidazolium ILs is simply because of the inadequate hydrophobicity of the imidazolium cation. Replacing the imidazolium cation with more hydrophobic tetrahexylammonium, the reductive charging of MPC films was observed. The ionic dependence manifests the charging process to be an ion-coupled electron transfer event, with the oxidative/reductive charging of MPCs at the electrode/film interface concomitant with the ionic partition at the film/IL interface. This system provides a diverse possibility of regulating the electronic properties of nanoparticle thin films by ionic/solvent functions, given that ILs are “designed solvents” with structures and functions easily tuned by ionic components (both anion and cation).
Co-reporter:Fei Yan, Wenjing Zheng, Lina Yao and Bin Su
Chemical Communications 2015 - vol. 51(Issue 100) pp:NaN17739-17739
Publication Date(Web):2015/10/16
DOI:10.1039/C5CC08425C
Herein we report a simple and cost-effective method for the direct electrochemical detection of redox-active small organic analytes in complex media, such as soil dispersions, human serum and milk, without sample pre-treatment using an indium tin oxide (ITO) electrode modified with permselective membranes consisting of vertically ordered surfactant micelles and silica mesochannels (OSM@SM). The OSM@SM/ITO electrode displayed excellent anti-interference and anti-fouling ability.
Co-reporter:Linru Xu, Zhenyu Zhou, Congzhe Zhang, Yayun He and Bin Su
Chemical Communications 2014 - vol. 50(Issue 65) pp:NaN9100-9100
Publication Date(Web):2014/06/20
DOI:10.1039/C4CC03466J
We present the combination of electrochemiluminescence imaging with enzyme immunoassay for the highly sensitive detection of protein/polypeptide residues in latent fingermarks. This technique provides an effective method for fingermark detection that enables both identification of an individual and recognition of the secretions in the human perspiration.
Co-reporter:Yan Li, Linru Xu and Bin Su
Chemical Communications 2012 - vol. 48(Issue 34) pp:NaN4111-4111
Publication Date(Web):2012/03/05
DOI:10.1039/C2CC30553D
The aggregation-induced emission of tetraphenylethene was explored for enhancing the visualization of latent fingerprints on wet non-porous surfaces.
Co-reporter:Suozhu Wu, Yunxia Zhang, Hong Shen, Bin Su and Qun Fang
Chemical Communications 2011 - vol. 47(Issue 20) pp:NaN5725-5725
Publication Date(Web):2011/04/18
DOI:10.1039/C0CC05815G
With a microfluidic droplet-based liquid/liquid extraction setup, we demonstrate that the extraction of an ionic analyte from complex matrices can be modulated by the interfacial Galvani potential difference and the extraction equilibrium follows the classical Nernst equation.
![Ferrate(4-), chloro[[4,4',4'',4'''-(21H,23H-porphine-5,10,15,20-tetrayl-κN21,κN22,κN23,κN24)tetrakis[benzenesulfonato]](6-)]-, hydrogen (1:4), (SP-5-12)-](/data/chemimg/2243800/90384-82-0.png)
![Ferrate(4-), chloro[[4,4',4'',4'''-(21H,23H-porphine-5,10,15,20-tetrayl-κN21,κN22,κN23,κN24)tetrakis[benzenesulfonato]](6-)]-, hydrogen (1:4), (SP-5-12)-](/data/chemimg/2243800/90384-82-0_b.png)
![Ferrate(4-),[L-valyl-L-glutaminyl-L-lysyl-L-cysteinyl-L-alanyl-L-glutaminyl-L-cysteinyl-L-histidyl-kN-L-threonyl-L-valyl-L-glutamicacid cyclic (4®12'),(7®7')-bis(thioether) with7,12-bis(1-mercaptoethyl)-3,8,13,17-tetramethyl-21H,23H-porphine-2,18-dipropanoato(6-)-kN21,kN22,kN23,kN24]-,hydrogen (1:4)](http://img.cochemist.com/ccimg/31000/30975-71-4.png)
![Ferrate(4-),[L-valyl-L-glutaminyl-L-lysyl-L-cysteinyl-L-alanyl-L-glutaminyl-L-cysteinyl-L-histidyl-kN-L-threonyl-L-valyl-L-glutamicacid cyclic (4®12'),(7®7')-bis(thioether) with7,12-bis(1-mercaptoethyl)-3,8,13,17-tetramethyl-21H,23H-porphine-2,18-dipropanoato(6-)-kN21,kN22,kN23,kN24]-,hydrogen (1:4)](http://img.cochemist.com/ccimg/31000/30975-71-4_b.png)
