We synthesized a new type of upper critical solution temperature (UCST) thermally responsive polymer (TRP) with varying responsive temperatures (cloud points). We then grafted one of the TRPs with a cloud point of 42 °C onto the surface of mesoporous silica nanoparticles (MSNs) using disulfide bonds to achieve a novel, dual responsive release system. With this system, the cargo release profiles are responsive to both temperature and reducing agents. When loaded with doxorubicin hydrochloride (DOX), the system could deliver DOX into breast cancer cells (SK-BR-3) in a controlled fashion and present high toxicity.

•A bifunctional silica nanoparticles FS-G has been synthesized.•FS-G can selectively detect Hg2+ in water with a detection limit of 33.4 ppb.•FS-G can work as an effective absorbent for trace Hg2+.•FS-G can be easily regenerated when treated with dimercaptosuccinic acid.Based on the thioether-rich crown receptor, we describe a naphthalimide based bifunctional fluorescent sensor (FS-G) for simultaneous detection and separation of trace Hg2+ in water. FS-G exhibited excellent selectivity toward Hg2+ in aqueous environment and showed 5-fold increase in fluorescence emission intensity upon the addition of Hg2+. A good linearity was observed between the fluorescence enhancement and the dose of Hg2+ with a lower detection limit of 33.4 ppb. Additionally, adsorption capacity of FS-G is 7.4 mg g−1. FS-G can be easily regenerated when treated with dimercaptosuccinic acid. These results indicate that FS-G has potential applications for detection and removal of trace Hg2+ in water.

Based on the 2,2-dipicolylamine (DPA) receptor and naphthalimide fluorophore, three fluorescent probes, RDPA, MDPA and VDPA have been developed for the recognition of mercuric ions. Among them, VDPA, bearing a diglycol group in the imine chain, exhibits good water solubility, and high selectivity towards mercuric ions in PBS water solution. With DPA as the receptor, VDPA showed very high affinity and sensitivity towards Hg2+, and the binding constant and detection limit were calculated to be 2.8 × 1010 M−1 and 5.49 nM, respectively. The MTT assay and living cell imaging experiments suggested that the probe VDPA has potential application for detecting Hg2+ in living cells.

Herein, we report a heterogenous catalyst (Pd@FSM) by immobilization of a novel Pd2+ sensor as promoter over mesoporous silica. Pd@FSM with a high palladium loading of ca. 11 mg g−1 exhibited superior catalytic activity for Suzuki–Miyaura cross-couplings and a catalyst loading of 0.05 mol% is typically sufficient to achieve excellent reaction yields. Notably, the reaction is typically carried out in water without removing atmospheric oxygen. The catalyst is conveniently recycled and remains highly active even after being recycled 5 times. During this process, loss of palladium from the solid support of the catalyst is negligible. Furthermore, the catalyst can be stored in air for at least three months without loss of its catalytic activity. This work provides a new approach to developing heterogeneous palladium catalysts by combing materials and fluorescent sensors.

A novel “turn-on” fluorescent probe HP for hypoxia imaging was designed and synthesized based on rhodamine B and a naphthalimide fluorophore. The fluorescence of HP is very weak owing to the FRET effect from rhodamine B to the azo-naphthalimide unit. Under hypoxia conditions, the azo-bond is reduced and the fluorescence at 581 nm enhances dramatically as a result of disintegration of the quencher structure. Verified by the cyclic voltammetry reduction potential and proposed product HPN, the probe HP could undergo the chemical and cytochrome P450 enzymatic reduction quickly. When cultured with HeLa cells, HP showed remarkable fluorescence differences at various oxygen concentrations, and the ratio of fluorescence intensity between hypoxic and normoxic cells could reach 9 fold.

A selective heterogeneous fluorescent sensor (FSM) for palladium was synthesized by grafting a small molecular fluorescent sensor onto mesoporous silica microspheres. FSM can selectively detect Pd2+ with a significant fluorescent quenching response, and the limit of detection was calculated to be 0.18 ppm. On the other hand, with silica microspheres as the matrix material, FSM is found to be able to remove trace palladium from water.

•A naphthalimide-based fluorescent probe CP has been synthesized with facile steps, which can selectively and sensitively recognize Cu2+ in water solution (100% H2O).•The Cu-containing complex CP@Cu can serve as a turn-on fluorescent probe demonstrating particular detection of histidine with low LOD, which exhibits remarkable fluorescence enhancement for dozens of times upon His added.•Such metal complex can be applied in the recognition of histidine rich proteins and the intracellular imaging of histidine.A naphthalimide-based fluorescent probe CP has been synthesized with simple steps. It can selectively and sensitively recognize copper ions (Cu2+) in HEPES buffer (50 mM, pH 7.2). The fluorescence intensity of CP is linearly proportional to the concentration of Cu2+ ranging from 0–8.3 μM (correlation coefficient R2=0.9808). The resulted complex CP@Cu can serve as a turn-on fluorescent probe for the detection of histidine and histidine rich proteins in broad pH application range. Upon the addition of histidine, the fluorescence intensity of CP@Cu exhibits a linear correlation with the concentration of histidine ranging from 0–200 μM (correlation coefficient R2=0.9912). Moreover, CP@Cu has potential for imaging histidine in vitro experiments and has promise in real sample applications with great validity.

Protein vicinal dithiols play fundamental roles in intracellular redox homeostasis due to their involvement in protein synthesis and function through the reversible vicinal dithiol oxidation to disulfide. To provide quantitative information about the global distribution and dynamic changes of protein vicinal dithiols in living cells, we have designed and synthesized a ratiometric fluorescent probe (VTAF) for trapping of vicinal dithiol-containing proteins (VDPs) in living cells. VTAF exhibits a ratiometric fluorescence signal upon single excitation, which enables self-calibration of the fluorescence signal and quantification of endogenous vicinal dithiols of VDPs. Its potential for in situ dynamic tracing of changes of protein vicinal dithiols under different cellular redox conditions was exemplified. VTAF facilitated the direct observation of subcellular distribution of endogenous VDPs via ratiometric fluorescence imaging and colocalization assay. And the results suggested that there are abundant VDPs in mitochondria. Moreover, some redox-sensitive VDPs are also present on cell surface which can respond to redox stimulus. This ratiometric fluorescence technique presents an important extension to previous fluorescence intensity-based probes for trapping and quantifying protein vicinal dithiols in living cells, as well as its visible dynamic tracing of VDPs.

A fluorescent probe (2a-LP) based on an unnatural amino acid (UAA) is developed for the detection of phenylalanine ammonia lyase (PAL). In the presence of PAL, 2a-LP is catalytically deaminated to ortho-amino-transcinnamic acid (o-a-CA), which shows a remarkable “off–on” fluorescence signal. Thus, the probe 2a-LP enables direct visualization of the PAL activity in tomato under UV illumination and has potential in vitro assays.

Sulfenylation is one of the reversible post-translational modifications, playing significant roles in cellular redox homeostasis and signaling systems. Herein, small fluorescent probe (CPD and CPDDM) based live-cell labelling technology for the visualization of protein sulfenylation responses in living cells has been developed. This approach enables the detection of protein sulfenylation without the need for cell lysis, fixation or purification, and permits the noninvasive study of protein sulfenylation in live cells through the direct fluorescent readout. This technology also can realize dynamic tracking of protein sulfenylation in situ with minimal perturbation to sulfenylated proteins and less interference with cellular function. Information on the global distribution and dynamic changes of endogenous protein sulfenylation has been obtained.

Through structure-based virtual screening, some dozen of benzene sulfonamides with novel scaffolds are identified as potent inhibitors against carbonic anhydrase (CA) IX with IC50 values ranging from 2.86 to 588.34 nM. Among them, compounds 1 and 9 show high selectivity against tumor-target CA IX over CA II (the selectivity ratios are 21.3 and 136.6, respectively). The possible binding poses of hit compounds are also explored and the selectivity is elucidated by molecular docking simulations. The hit compounds discovered in this work would provide novel scaffolds for further hit-to-lead optimization.

A polymeric fluorescent sensor PNME, consisting of A4 and N-isopropylacrylamide (NIPAM) units, was synthesized. PNME exhibited dual responses to pH and temperature, and could be used as an intracellular pH sensor for lysosomes imaging. Moreover, it also could sense different temperature change in living cells at 25 and 37 °C, respectively.

A glucose-responsive controlled-release system based on the competitive combination between glucose oxidase, glucosamine and glucose has been described, which exhibits perfect controlled release properties and high selectivity for glucose over other monosaccharides. This paved the way for a new generation of stimuli-responsive delivery systems.

A novel ratiometric fluorescent probe for oxalic acid was designed and synthesized, based on the zinc-containing [DAQZ@2Zn2+] complex. It shows highly selective “on-off” fluorescence changes with a more than 20 nm blue shift in wavelength for oxalic acids in aqueous solution. Moreover, it can fluorescently respond to oxalic acid in living cells.

In this work, three kinds of core–shell silica nanoparticle-based fluorescent materials were prepared based on a modified Stöber–Van Blaaderen method. They were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), FT-IR, and several other spectroscopic methods. Firstly, The silica@sensor-1 nanoparticle (SSN) showed high selectivity toward Zn2+, which can detect Zn2+ in aqueous solution and living cells. It also can be reused to detect Zn2+ for at least four cycles after a simple regeneration. Secondly, to create a ratiometric measurement platform, the dye-2@silica nanoparticles (DSN), a new class of core–shell fluorescent silica nanoparticles were prepared with an acenaphtho[1, 2-b]pyrrol-9-carbonitrile chromophore derivative as the inner reference. It showed negligible sensing properties towards Zn2+, and the fluorescent intensity was not subjected to interference induced by pH change. Thirdly, the dye-2@silica@sensor-1 nanoparticles (DSSN), with the above reference dye buried inside the silica matrix and a layer of chemosensors anchored onto the surface of silica nanoparticles were prepared. DSSN showed not only the same sensing ability as SSN, but also a clear ratiometric fluorescent signal toward Zn2+ in aqueous solutions and living cells. On the other hand, H2PO4− is a well-known Zn2+ binder, so the [DSSN@Zn2+] complex was found to ratiometrically detect H2PO4−. It responded to H2PO4− at a neutral aqueous solution with a detection limit lower than 6 × 10−6 M. Moreover, the ratio of fluorescence intensity was linearly increased in the range 6∼500 μM of H2PO4−, which implies a potential application for the quantitation of H2PO4− in aqueous solution. To the best of our knowledge, this is the first example of core–shell silica nanoparticle-based fluorescent materials that can be repeatedly used to ratiometrically detect Zn2+ and H2PO4− in 100% neutral aqueous solutions.

A new fluorescent sensor 1, based on the naphthalimide chromophore and thioether-rich crown receptor, exhibited dual signaling behaviors for Hg2+ and Ag+ in aqueous solution. Upon addition of Hg2+, the fluorescence intensity enhanced in a linear fashion with a quantum yield increase of about 5-fold. Moreover, with the 1-Hg2+ complex, Ag+ was easily recognized by a marked fluorescence quenching. The living cells image experiments demonstrate the value of sensor 1 in fluorescent visualization of Hg2+ ions in biological systems.

In this work, a reusable bifunctional fluorescent sensor for simultaneous detection and separation of trace Hg2+ in water and serum, which contains a naphthalimide derivative of 2,6-bis(aminomethyl)pyridine covalently grafted to the surface of silica particles, was developed. Meanwhile, the fluorescence characteristics and the adsorbent properties of the sensor were investigated in detail. This sensor showed a very good linearity (correlation coefficient of R2 = 0.9991) in the range 0.1–1 μM of Hg2+ with detection limits lower than 6.8 × 10−9 M. It can also be used as an adsorbent for the removal of mercuric ions from the contaminated aqueous solution. The regeneration of this sensor is very simple, only by modulating the pH value of the aqueous solution. It can be reused at least four cycles. In addition, the present approach has the advantages of rapidity, simplicity, and low cost. We believe that this approach may serve as a foundation for the preparation of practical fluorescent sensor for the rapid detection of Hg2+ in aqueous biological and environmental samples.

Based on the 2,2-dipicolylamine (DPA) receptor and naphthalimide fluorophore, three fluorescent probes, RDPA, MDPA and VDPA have been developed for the recognition of mercuric ions. Among them, VDPA, bearing a diglycol group in the imine chain, exhibits good water solubility, and high selectivity towards mercuric ions in PBS water solution. With DPA as the receptor, VDPA showed very high affinity and sensitivity towards Hg2+, and the binding constant and detection limit were calculated to be 2.8 × 1010 M−1 and 5.49 nM, respectively. The MTT assay and living cell imaging experiments suggested that the probe VDPA has potential application for detecting Hg2+ in living cells.

A novel ratiometric fluorescent probe for oxalic acid was designed and synthesized, based on the zinc-containing [DAQZ@2Zn2+] complex. It shows highly selective “on-off” fluorescence changes with a more than 20 nm blue shift in wavelength for oxalic acids in aqueous solution. Moreover, it can fluorescently respond to oxalic acid in living cells.

A selective heterogeneous fluorescent sensor (FSM) for palladium was synthesized by grafting a small molecular fluorescent sensor onto mesoporous silica microspheres. FSM can selectively detect Pd2+ with a significant fluorescent quenching response, and the limit of detection was calculated to be 0.18 ppm. On the other hand, with silica microspheres as the matrix material, FSM is found to be able to remove trace palladium from water.

A polymeric fluorescent sensor PNME, consisting of A4 and N-isopropylacrylamide (NIPAM) units, was synthesized. PNME exhibited dual responses to pH and temperature, and could be used as an intracellular pH sensor for lysosomes imaging. Moreover, it also could sense different temperature change in living cells at 25 and 37 °C, respectively.

A fluorescent probe (2a-LP) based on an unnatural amino acid (UAA) is developed for the detection of phenylalanine ammonia lyase (PAL). In the presence of PAL, 2a-LP is catalytically deaminated to ortho-amino-transcinnamic acid (o-a-CA), which shows a remarkable “off–on” fluorescence signal. Thus, the probe 2a-LP enables direct visualization of the PAL activity in tomato under UV illumination and has potential in vitro assays.

A new fluorescent sensor 1, based on the naphthalimide chromophore and thioether-rich crown receptor, exhibited dual signaling behaviors for Hg2+ and Ag+ in aqueous solution. Upon addition of Hg2+, the fluorescence intensity enhanced in a linear fashion with a quantum yield increase of about 5-fold. Moreover, with the 1-Hg2+ complex, Ag+ was easily recognized by a marked fluorescence quenching. The living cells image experiments demonstrate the value of sensor 1 in fluorescent visualization of Hg2+ ions in biological systems.

In this work, three kinds of core–shell silica nanoparticle-based fluorescent materials were prepared based on a modified Stöber–Van Blaaderen method. They were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), FT-IR, and several other spectroscopic methods. Firstly, The silica@sensor-1 nanoparticle (SSN) showed high selectivity toward Zn2+, which can detect Zn2+ in aqueous solution and living cells. It also can be reused to detect Zn2+ for at least four cycles after a simple regeneration. Secondly, to create a ratiometric measurement platform, the dye-2@silica nanoparticles (DSN), a new class of core–shell fluorescent silica nanoparticles were prepared with an acenaphtho[1, 2-b]pyrrol-9-carbonitrile chromophore derivative as the inner reference. It showed negligible sensing properties towards Zn2+, and the fluorescent intensity was not subjected to interference induced by pH change. Thirdly, the dye-2@silica@sensor-1 nanoparticles (DSSN), with the above reference dye buried inside the silica matrix and a layer of chemosensors anchored onto the surface of silica nanoparticles were prepared. DSSN showed not only the same sensing ability as SSN, but also a clear ratiometric fluorescent signal toward Zn2+ in aqueous solutions and living cells. On the other hand, H2PO4− is a well-known Zn2+ binder, so the [DSSN@Zn2+] complex was found to ratiometrically detect H2PO4−. It responded to H2PO4− at a neutral aqueous solution with a detection limit lower than 6 × 10−6 M. Moreover, the ratio of fluorescence intensity was linearly increased in the range 6∼500 μM of H2PO4−, which implies a potential application for the quantitation of H2PO4− in aqueous solution. To the best of our knowledge, this is the first example of core–shell silica nanoparticle-based fluorescent materials that can be repeatedly used to ratiometrically detect Zn2+ and H2PO4− in 100% neutral aqueous solutions.

Sulfenylation is one of the reversible post-translational modifications, playing significant roles in cellular redox homeostasis and signaling systems. Herein, small fluorescent probe (CPD and CPDDM) based live-cell labelling technology for the visualization of protein sulfenylation responses in living cells has been developed. This approach enables the detection of protein sulfenylation without the need for cell lysis, fixation or purification, and permits the noninvasive study of protein sulfenylation in live cells through the direct fluorescent readout. This technology also can realize dynamic tracking of protein sulfenylation in situ with minimal perturbation to sulfenylated proteins and less interference with cellular function. Information on the global distribution and dynamic changes of endogenous protein sulfenylation has been obtained.

A novel “turn-on” fluorescent probe HP for hypoxia imaging was designed and synthesized based on rhodamine B and a naphthalimide fluorophore. The fluorescence of HP is very weak owing to the FRET effect from rhodamine B to the azo-naphthalimide unit. Under hypoxia conditions, the azo-bond is reduced and the fluorescence at 581 nm enhances dramatically as a result of disintegration of the quencher structure. Verified by the cyclic voltammetry reduction potential and proposed product HPN, the probe HP could undergo the chemical and cytochrome P450 enzymatic reduction quickly. When cultured with HeLa cells, HP showed remarkable fluorescence differences at various oxygen concentrations, and the ratio of fluorescence intensity between hypoxic and normoxic cells could reach 9 fold.

A glucose-responsive controlled-release system based on the competitive combination between glucose oxidase, glucosamine and glucose has been described, which exhibits perfect controlled release properties and high selectivity for glucose over other monosaccharides. This paved the way for a new generation of stimuli-responsive delivery systems.