Herein, a simple bi-photochromic molecule containing a donor–acceptor Stenhouse adduct and azobenzene moiety was synthesized. It can achieve all-photonic multimolecular logic functions and photo-printing. This molecule could provide a novel platform for exploring multifunctional molecular logic devices.

•A novel quantitative detection of the membrane proteins on cell•The detection of PTK-7 displays a detection limit of 12 pM.•This is a universal method for ultrasensitive of embrane protein detectionRecently, membrane proteins have been considered as candidate cancer biomarkers and drug targets, due to their important roles in numerous physiological processes. Therefore, a facile, sensitive and quantitative detection of the membrane proteins is crucial for better understanding their roles in cancer cells and further validating their function in clinical research. We report a highly facile and sensitive detection method for membrane proteins on living cells in situ based on membrane protein-triggered release of cytosine (C)-rich single-stranded DNA (ssDNA) sequences, and the subsequent silver nanoclusters (AgNCs) transfer from polymer to C-rich ssDNA. The high-quantum yield and stable DNA-AgNCs allow the accurate detection of membrane proteins with facile operations and a common fluorescence spectrophotometer. The detection of protein tyrosine kinase-7 (PTK7), a membrane protein model, displays a response range from 30 pM to 2 nM with a detection limit of 12 pM. The expression of PTK7 on single Hela cell and CCRF-CEM cell was calculated to be 7.5 × 10−19 mol and 1.8 × 10−18 mol, respectively. Given the simple and facile operation of this method, this detection platform can be applied as a universal strategy for ultrasensitive detection of membrane protein on cell in situ.A strategy for membrane protein tyrosine kinase-7 in situ detection based on the protein triggered C-rich ssDNA sequence release and the silver nanoclusters transfer between the polymer template and C-rich sequence was developed. It shows a detection range from 30 pM to 2 nM with a detection limit of 12 pM. This strategy can realize quantitative detection simply and conveniently comparing with other methods which rely on complex instrumentation.Download high-res image (215KB)Download full-size image

Merocyanine dyes, owing to their unique photochemical properties, are widely used to fabricate probes for the detection of biologically active small molecules and bioimaging. In this paper, merocyanine-based probes were proved of undergoing unwanted hydrolysis. To explore the strategies toward avoiding the hydrolysis, the detailed hydrolysis mechanism was first investigated, which was also confirmed by density functional theory (DFT) calculation. Then a series of merocyanine dyes were rationally designed. Influences of molecular structures of the probes, the analytical media such as pH and components of the solution on the hydrolysis were systematically studied. The experimental results suggest that merocyanine based probes with low electron density are more likely to suffer the hydrolysis, which could be exacerbated by the well-accepted strategy for constructing type-II probes. It is worth noting that chemical surroundings could also exert distinctive influence on the hydrolysis. The hydrolysis could be obviously aggravated when fetal calf serum or DMSO was deployed. Our findings will definitely provide an effective and reliable approach for guiding the rational design of highly robust merocyanine-based probes and the optimization of the analytical media, which is helpful in terms of avoiding the hydrolysis of the probes and hydrolysis caused analytical errors.

•We have developed a new lysosome-targeting AIE fluorescent probe TPE-MPL.•Noninvasive imaging and monitoring the morphological changes of lysosomes.•Fluorescent imaging and tracing lysosomes with high spatial and temporal resolution.We develop a new lysosome-targeting AIE fluorescent probe tetraphenylethene-morpholine (TPE-MPL), by incorporating a typical lysosome-targeting moiety of morpholine into a stable tetraphenylethene skeleton. Due to both the AIE and antenna effects, TPE-MPL possesses superior photostability, appreciable tolerance to microenvironment change and high lysosome targeting ability. Our findings confirm that TPE-MPL is a well-suited imaging agent for targeting lysosome and tracking dynamic movement of lysosome. Moreover, due to its synthetic accessibility, TPE-MPL could be further modified as a dual-functional probe for lysosome, thereby gain further insight into the role of lysosome in biomedical applications.A novel lysosome-targetable AIE fluorescent probe TPE-MPL with high photostability, appreciable tolerance to microenvironment change and high lysosome targeting properties was developed. It can be used for noninvasive imaging of lysosomes and tracking the dynamic movements of lysosomes with high spatial and temporal resolution and can track lysosomes morphology in cell apoptosis.

Glycoproteins are important biomarkers and therapeutic targets in clinical diagnostics. The conventional analytical methods for glycoprotein are usually faced with some challenges, such as the complex pretreatment of samples, poor availability, and limited stability of antibody, making them not suitable for point-of-care and on-site application. Herein, we demonstrate a novel miniaturized biofuel cells (BFCs)-based self-powered nanosensor for the specific and sensitive determination of glycoproteins in complex samples through the combination of boronate-affinity molecularly imprinted polymer (MIP) and the boronate affinity functionalized biliroxidase–carbon nanotube nanocomposites. The above MIP and the nanocomposites act as both signal probe and biocatalyst at the cathode. The as-obtained self-powered MIP–BFC-based biosensor can detect horseradish peroxidase (a type of glycoprotein) with a wide linear range of 1 ng/mL to 10 μg/mL and a very low detection limit of 1 ng/mL. Especially, it shows high tolerance for different interferences (e.g., sugars and other glycoproteins) and can even measure the α-fetoprotein level in serum samples. Moreover, it exhibits significant advantages over the conventional assays in terms of cost efficiency, stability, and speed, especially inexpensive instrument needed. Our novel approach for construction of the sensor paves a simple and economical way to fabricate portable devices for point-of-care and on-site application.Keywords: biofuel cell; biosensor; glycoprotein; protein-imprinted polymer; self-power;

A NIR light induced H2S release platform based on UCNPs was constructed. Under NIR light excitation, UCNPs can emit UV light which triggers H2S release in a spatial and temporal pattern. The platform was also employed to real-time monitor the delivery process in vivo, which may provide a new way for the use of H2S-based therapeutics for a variety of diseases.

This manuscript introduces a simple method to fabricate hybrid aerogels with Fe3O4 nanocrystals/nitrogen-doped graphene (Fe3O4/N-GAs) through one-shot self-mineralization of ferrocenoyl phenylalanine/graphene oxide (Fc-F/GO) supramolecular hydrogels. We found that GO could trigger a sol–gel transition of Fc-F gelators below the critical gelation concentration and the electron microscopic results revealed that the self-assembled Fc-F fibrils tightly bound onto graphene sheets. Upon hydrothermal reaction, Fc moieties in these fibrils could be locally oxidized to Fe3O4 nanocrystals by GO, remaining on the top of reduced GO (RGO) sheets and therefore inhibiting the self-aggregation of graphene nanosheets. After drying, the remains of the supramolecular hybrid hydrogels are presented as the three-dimensional (3D) framework of ultra-thin graphene sheets on which Fe3O4 nanoparticles (NPs) are uniformly immobilized as single crystals. Since the new born Fe3O4 nanocrystals are closely anchored on the graphene sheets, the as-prepared Fe3O4/N-GAs complex shows excellent electrocatalytic activity for the oxygen reduction reaction (ORR, compared to commercial Pt/C). Notably, the Fc-F/GO supramolecular hydrogels act as multifunctional reagents, such as capping agents for preventing graphene nanosheets from stacking and Fe and N sources for Fe3O4/N-GAs. We expect that this intriguing strategy can provide a useful archetypical example in designing nonprecious metal oxides/carbon hybrid materials to serve as substitutes for noble metal catalysts.

We demonstrated a biofuel cells (BFCs)-based self-powered sensing system for the detection of Nε-(carboxymethyl)lysine (CML), in which the bilirubin oxidase (BOD)–carbon nanotube (CNT) bioconjugate modified with antibody acted as a biocatalyst for enhancing O2 reduction in the biocathode, as well as the transducing enzyme for signaling magnification. With an increase in the concentration of CML, the amount of BOD labels on biocathode surface increases, thus leading to the higher output of the as-prepared BFCs. This novel BFCs-based self-powered sensor showed a wide linear range for analyzing CML from 1 nM to 100 μM with a detection limit of 0.2 nM, which was 50 times more sensitive than that determined from the conventional ELISA. Most importantly, our new self-powered sensing platform can determine the level of CML in serum samples from multiple healthy donors and multiple sclerosis patients, being well in accordance with that from the commercial ELISA analysis.

•Uniform polyaniline (PANI) nanowire was prepared by using peptide assembled fibers as the template.•A novel electrochemical biosensor was constructed based on the high electrochemical activity of the PANI nanowire.•The biosensor displayed high sensitivity and selectivity for hepatitis B virus gene.A novel electrochemical active polyaniline (PANI) nanowire was fabricated and utilized for the construction of a highly sensitive and selective electrochemical sensor for hepatitis B virus gene. The uniform PANI nanowire was prepared by the enzymatic polymerization of aniline monomers on the amyloid-like nanofiber (AP nanowire), which was self-assembled from an aniline-attached nonapeptide, aniline-GGAAKLVFF (AP). The prepared PANI nanowires were characterized by electron microscopy, UV–vis absorption spectra, and cyclic voltammetry (CV). These ultra-thin nanowires displayed high electrochemical activity. Then the nucleic acid biosensor was constructed by modifying a glass carbon electrode with AP nanowires which were functionalized by a designed hair-pin loop DNA. Upon the presence of target nucleic acid and horseradish peroxidase (HRP) labeled oligonucleotide, the HRP will catalyze the polymerization of aniline monomers conjugated in AP nanowires, leading to the formation of PANI nanowires which can bring about a dramatical increase in the current response of the biosensor. The dynamic range of the sensor for hepatitis B virus gene is 2.0–800.0 fM with a low detection limit of 1.0 fM (3σ, n=10). The biosensor also displayed highly selectivity and stability. All these excellent performances of the developed biosensor indicate that this platform can be easily extended to the detection of other nucleic acids.

An aniline–GGAAKLVFF peptide (AFP) was prepared by solid-phase synthesis. The peptide can readily self-assemble into fibrils. Platinum nanoparticles (Pt NPs) were directly immobilized on the surface of the AFP fibrils via electrostatic interaction. Compared to other currently available techniques for the fabrication of metal–peptide fibrils, the noncovalent functionalization strategy is able to deposit nanoparticles on peptide fibrils with different morphologies and high metal loading, which is important for applications in catalysis, electronic materials and other corresponding fields. The Pt–AFP fibrils were employed to modify the electrode, which exhibits high electrocatalytic activities towards oxygen reduction. Thus, the Pt–AFP fibrils hold great potential for polymer electrolyte fuel cells and other electrochemical applications.

In this paper, we fabricate a sensitive and stable amperometric UA amperometric biosensor using nanobiocomposite derived from thionine modified graphene oxide in this study. A simple wet-chemical strategy for synthesis of thionine–graphene oxide hybrid nanosheets (T–GOs) through π–π stacking has been demonstrated. Various techniques, such as UV–vis absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), atomic force microscopy (AFM) and electrochemistry have been utilized to characterize the formation of the T–GOs. Due to the synergistic effect between thionine and graphene oxide, the nanosheets exhibited excellent performance toward H2O2 reduction. The incorporation of thionine onto graphene oxide surface resulted in more than a twice increase in the amperometric response to H2O2 of the thionine modified electrode. The as-formed T–GOs also served as a biocompatible matrix for enzyme assembly and a mediator to facilitate the electron transfer between the enzyme and the electrode. Using UOx as a model system, we have developed a simple and effective sensing platform for assay of uric acid at physiological levels. UA has been successfully detected at −0.1 V without any interference due to other electroactive compounds at physiological levels of glucose (5 mM), ascorbic acid (0.1 mM), noradrenalin (0.1 mM), and dopamine (0.1 mM). The response displays a good linear range from 0.02 to 4.5 mM with detection limit 7 μM. The application of this modified electrode in blood and urine UA exhibited a good performance. The robust and advanced hybrid materials might hold great promise in biosensing, energy conversion, and biomedical and electronic systems.Graphical abstractHighlights► A simple wet-chemical strategy for synthesis of thionine–graphene oxide hybrid nanosheets (T–GOs). ► T–GOs serve as a biocompatible matrix for enzyme assembly and a mediator. ► A simple and effective sensor for assay of uric acid at physiological levels. ►Demonstrate further application of GOs for biosensors and other fields.

A simple spectrophotometric assay of H2O2 and glucose using Ag nanoparticles has been carried out. Relying on the synergistic effect of H2O2 reduction and ultraviolet (UV) irradiation, Ag nanoparticles with enhanced absorption signals were synthesized. H2O2 served as a reducing agent in the Ag nanoparticles formation in which Ag+ was reduced to Ag0 by O2− generated via the decomposition of H2O2 in alkaline media. On the other hand, photoreduction of Ag+ to Ag0 under UV irradiations also contributed to the nanoparticles formation. The synthesized nanoparticles were characterized by TEM, XPS, and XRD. The proposed method could determine H2O2 with concentrations ranging from 5.0 × 10−7 to 6.0 × 10−5 mol/L. The detection limit was estimated to be 2.0 × 10−7 mol/L. Since the conversion of glucose to gluconic acid catalyzed by glucose oxidase was companied with the formation of H2O2, the sensing protocol has been successfully utilized for the determination of glucose in human blood samples. The results were in good agreement with those determined by a local hospital. This colorimetric sensor thus holds great promises in clinical applications.A simple spectrophotometric assay of H2O2 and glucose using Ag nanoparticles has been carried out. This colorimetric method holds a great promise in clinical applications.

A NIR light induced H2S release platform based on UCNPs was constructed. Under NIR light excitation, UCNPs can emit UV light which triggers H2S release in a spatial and temporal pattern. The platform was also employed to real-time monitor the delivery process in vivo, which may provide a new way for the use of H2S-based therapeutics for a variety of diseases.