An aptasensor for chloramphenicol determination based on dual signal output of photoelectrochemistry and colorimetry.

In the present work, we developed an aptasensor to determine chloramphenicol (CAP) based on the dual signal output of photoelectrochemistry (PEC) and colorimetry. The Fe-doped porous tungsten trioxide was prepared by sol-gel method and coated on the ITO conductive glass to form ITO/p-W(Fe)O. After assembling the captured DNA (cDNA) and the aptamer of CAP (apt) successively, the constructed ITO/p-W(Fe)O-cDNA/apt aptasensor exhibited excellent photocurrent response under visible light irradiation in the presence of glucose, which provided the feasibility for PEC measurement with high sensitivity.

A photoelectrochemical aptasensor for omethoate determination based on a photocatalysis of CeO@MnO heterojunction for glucose oxidation.

In the present work, we developed a photoelectrochemical aptasensor to determine omethoate (OMT) based on the dual signal amplification of CeO@MnO photocatalysis for glucose oxidation and exonuclease I-assisted cyclic catalytic hydrolysis. CeO@MnO heterojunction material prepared by hydrothermal method was linked with captured DNA (cDNA) and then assembled on the ITO conductive glass to form ITO/CeO@MnO-cDNA, which exhibited significant photocurrent response and good photocatalytic performance for glucose oxidation under visible light irradiation, providing the feasibility for sensitive determining OMT. After binding with the aptamer of OMT (apt), the formation of rigid double stranded cDNA/apt kept CeO@MnO away from ITO surface, which ensured a low photocurrent background for the constructed ITO/CeO@MnO-cDNA/apt aptasensor.

A colorimetric aptasensor for CA125 determination based on dual catalytic performance of CeO nanozyme confined in macroporous silica foam.

A portable colorimetric aptasensor was constructed based on the dual catalytic performance of CeO nanozyme to determine carbohydrate antigen 125 (CA125). Firstly, CeO nanozyme was synthesized by calcination and ultrasonically dispersed in a macroporous silica foam (MSF) to form CeO@MSF. Then the aptamer of CA125 (apt) and complementary DNA (c-DNA) were successively assembled on the CeO@MSF to construct a CeO@MSF/apt/c-DNA colorimetric aptasensor, which exhibited excellent oxidase-mimic performance and phosphatase-mimic activity simultaneously.

Confined catalysis of MOF-818 nanozyme and colorimetric aptasensing for cardiac troponin I.

Understanding the catalytic performance of nanozymes assembled in confined environment is an interesting topic. Herein, a three-dimensional nanozyme-catalytic nanoreactor was constructed by confining MOF-818 nanozyme in the pore of macroporous tungsten trioxide (p-WO). The catalytic activity of MOF-818 assembled in-situ for the oxidation of 3,5-Di-tert-butylcatechol (3,5-DTBC) could be regulated by changing the pore size of p-WO.

Photoelectrochemical aptasensing for thrombin based on exonuclease III-assisted recycling signal amplification and nanoceria enzymatic strategy.

In the present work, a capture DNA (c-DNA) was immobilized on the TNA/g-CN to develop a sensitive and selective TNA/g-CN/c-DNA photoelectrochemical aptasensor for determining thrombin. With the aid of the specific recognition of anti-thrombin aptamer towards thrombin, ingenious design of hairpin DNA, and exonuclease III-assisted recycling signal amplification, more nanoceria could be assembled on the TNA/g-CN/c-DNA to form TNA/g-CN/nanoceria in the presence of thrombin. Due to the oxidase-mimic catalytic efficiency of nanoceria and the oxygen consumption for glucose oxidation, the photoexcited electrons at the conduction band of g-CN could be well transferred to that of TNA under visible light irradiation, resulting in the increase of the photocurrent of TNA/g-CN/nanoceria, and the increase value of photocurrent had a linear relationship with the concentration of thrombin under the optimal conditions.

Self-powered aptasensing for prostate specific antigen based on a membraneless photoelectrochemical fuel cell.

A self-powered aptasensor for prostate specific antigen (PSA) based on a membraneless photoelectrochemical fuel cell (PEFC) with double photoelectrodes was constructed, in which, PSA-binding aptamer was electrostatically immobilized on the KOH-doped g-CN modified TiO nanotube arrays (TNA/A-g-CN/aptamer), which was used as a photoanode, and Fe-doped CuBiO modified indium doped tin oxide (ITO) substrate (ITO/CBFeO) was used as a photocathode. Under visible light irradiation, glucose was photocatalytically oxidized by A-g-CN and generated HO in situ, which was used as the electron acceptor for ITO/CBFeO photocathode, thus producing a high cell output response with a maximum output power of 133.5 μW cm and an open circuit potential of 0.

Photoelectrochemically driven bioconversion and determination of nifedipine based on a double photoelectrode system.

In the present work, a double photoelectrode system has been constructed for photoelectrochemically driven enzymatic bioconversion and determination of nifedipine. In which, the TiO nanotube arrays in-situ assembled with g-CN (TNA/g-CN) was used as a photoanode, and a cytochrome P450 3A4 (CYP3A4) enzyme was immobilized in the porous ITO/CuO films to fabricate an ITO/CuO/CYP3A4 photocathode. The constructed double photoelectrode system had a significant photocurrent response compared to the single ITO/CuO/CYP3A4 or TNA/g-CN under visible light irradiation.

Photoelectrochemical determination of alkaline phosphatase activity based on a photo-excited electron transfer strategy.

A sensitive photoelectrochemical (PEC) biosensor for determination of alkaline phosphatase (ALP) activity was constructed based on a photo-excited electron transfer strategy. Immobilization of CdTe quantum dots (QDs) on TiO nanotube arrays (TNAs), addition of iron (III) and adenosine triphosphate (ATP) in turn can effectively adjust the photocurrent response of TNAs under visible light irradiation due to a photo-excited electron transfer process, and alkaline phosphatase (ALP) activity can be determined for its catalysis toward dephosphorylation of ATP. The preparation of CdTe QDs, construction of TNA/QD PEC biosensor and the mechanism of photo-excited electron transfer are investigated in the present work.

Photoelectrochemical TiO nanotube arrays biosensor for asulam determination based on in-situ generation of quantum dots.

Inspired by the photoelectrochemical (PEC) properties of TiO nanotubes arrays (TNA) and their application as a super vessel for immobilizing biomolecules, we constructed an inhibition-effect PEC biosensor for determination of asulam based on the in-situ generation of CdS quantum dots (QDs) on TNA using an enzymatic reaction. Horseradish peroxidase (HRP) enzyme was covalently assembled on the inner-wall of TNAs, which exhibited good electrochemical and catalytic properties. In the mixture solution containing HO, CdY and SO, HRP enzyme in TNAs catalyzed HO reduce SO to S.

Fluorescence resonance energy transfer aptasensor between nanoceria and graphene quantum dots for the determination of ochratoxin A.

In the present work, colloidal cerium oxide nanoparticles (nanoceria) and graphene quantum dots (GQDs) were firstly synthesized by sol-gel method and pyrolysis respectively, which all have a uniform nano-size and significant fluorescence emission. Due to the fluorescence emission spectrum of nanoceria overlapped the absorption spectrum of GQDs, fluorescence resonance energy transfer (FRET) between nanoceria and GQDs could occur effectively by the electrostatic interaction. Based on it, a sensitive ratiometric fluorescence aptasensor for the determination of ochratoxin A (OTA), a small molecular mycotoxin produced by Aspergillus and Penicillium strains, has been successfully constructed.

Recent advances in real-time and in situ analysis of an electrode-electrolyte interface by mass spectrometry.

Electrode-electrolyte interface (EEI) analysis is of great significance in the investigation of electrochemical (EC) processes. Current ex situ surface techniques provided rich information of the structural/chemical composition of the EEI. However, real-time and in situ monitoring of the EEI is in great demand for a better understanding of the dynamic changes of the redox systems.

Enhanced light-driven catalytic performance of cytochrome P450 confined in macroporous silica.

A light-driven approach combined with a macroporous reactor for the enzymatic biocatalytic reaction has been developed by confining the enzyme/photosensitizer nanohybrids in a macroporous material, which exhibits high bio-conversion efficiency due to the fast diffusion and collision between the enzyme/photosensitizer nanohybrid and the substrate in the reactor.

A novel photoelectrochemical immunosensor by integration of nanobody and TiO₂ nanotubes for sensitive detection of serum cystatin C.

Cystatin C (CysC) is a sensitive marker for the estimation of the glomerular filtration rate and the clinical diagnosis of different diseases. In this paper, CysC-specific nanobodies (Nbs) were isolated from a phage display nanobody library. A simple and sensitive photoelectrochemical immunosensor based on TiO2 nanotube arrays (TNAs) was proposed for the sensitive detection of CysC.

Novel chemiluminescent imaging microtiter plates for high-throughput detection of multiple serum biomarkers related to Down's syndrome via soybean peroxidase as label enzyme.

Novel chemiluminescent (CL) imaging microtiter plates with high-throughput, low-cost, and simple operation for detection of four biomarkers related to Down's syndrome screening were developed and evaluated. To enhance the sensitivity of CL immunosensing, soybean peroxidase (SBP) was used instead of horseradish peroxide (HRP) as a label enzyme. The microtiter plates were fabricated by simultaneously immobilizing four capture monoclonal antibodies, anti-inhibin-A, anti-unconjugated oestriol (anti-uE3), anti-alpha-fetoprotein (anti-AFP), and beta anti-HCG (anti-β-HCG), on nitrocellulose (NC) membrane to form immunosensing microtiter wells.

Synthesis of fluorescent dye-doped silica nanoparticles for target-cell-specific delivery and intracellular microRNA imaging.

MicroRNA (miRNA) is found to be up-regulated in many kinds of cancer and therefore is classified as an oncomiR. Herein, we design a multifunctional fluorescent nanoprobe (FSiNP-AS/MB) with the AS1411 aptamer and a molecular beacon (MB) co-immobilized on the surface of the fluorescent dye-doped silica nanoparticles (FSiNPs) for target-cell-specific delivery and intracellular miRNA imaging. The FSiNPs were prepared by a facile reverse microemulsion method from tetraethoxysilane and silane derivatized coumarin that was previously synthesized by click chemistry.

Electrochemically driven drug metabolism via a CYP1A2-UGT1A10 bienzyme confined in a graphene nano-cage.

A graphene nano-cage with regulatable space for the assembly of a cytochrome P450 1A2-UDP-glucuronosyltransferase 1A10 bienzyme complex has been constructed via a click reaction, and successfully used to study drug sequential metabolism using an electrochemically-driven method.

Nanocomposites of graphene and cytochrome P450 2D6 isozyme for electrochemical-driven tramadol metabolism.

Cytochrome P450 enzymes (cyt P450s) with an active center of iron protoheme are involved in most clinical drugs metabolism process. Herein, an electrochemical platform for the investigation of drug metabolism in vitro was constructed by immobilizing cytochrome P450 2D6 (CYP2D6) with cyt P450 reductase (CPR) on graphene modified glass carbon electrode. Direct and reversible electron transfer of the immobilized CYP2D6 with the direct electron transfer constant of 0.

Enhanced enzymatic reactivity for electrochemically driven drug metabolism by confining cytochrome P450 enzyme in TiO₂ nanotube arrays.

Understanding the enzymatic reaction kinetics that occur within a confined space or interface is a significant challenge. Herein, a nanotube array enzymatic reactor (CYP2C9/Au/TNA) was constructed by electrostatically adsorbing enzyme on the inner wall of TiO2 nanotube arrays (TNAs). TNAs with different dimensions could be fabricated by the anodization of titanium foil through varying the anodization potential or time.

Target-cell-specific fluorescence silica nanoprobes for imaging and theranostics of cancer cells.

MicroRNAs (miRNAs) has been identified as diagnostic and prognostic biomarkers and predictors of drug response for many diseases, including a broad range of cancers, heart disease, and neurological diseases. The noninvasive theranostics system for miRNAs is very important for diagnosis and therapy of the cellular disease. Herein, a target-cell-specific theranostics nanoprobe for target-cell-specific delivery, cancer cells and intracellular miRNA-21 imaging, and cancer cell growth inhibition was proposed.

Flow injection chemiluminescence immunoassay of microcystin-LR by using PEI-modified magnetic beads as capturer and HRP-functionalized silica nanoparticles as signal amplifier.

A rapid sandwiched immunoassay of microcystin-LR (MC-LR) in water is proposed with flow injection chemiluminescence detection. The magnetic beads (MBs) were first modified with polyethyleneimine (PEI) by acylamide bond between the carboxyl group on the surface of MBs and the primary amine group in PEI, followed by immobilizing of anti-MC-LR (Ab1) onto PEI with glutaraldehyde as linkage. The resulting Ab1 modified MBs captured the target MC-LR in water, reacted with the horseradish peroxidase and anti-MC-LR co-immobilized silica nanoparticles, and were detected with flow injection chemiluminescence.

Microemulsion extraction separation and determination of aluminium species by spectrofluorimetry.

A simple and sensitive microemulsion extraction separation method was developed for the speciation of aluminium in tea samples by spectrofluorimetry. With 8-hydroxyquinoline (8-HQ) as the chelating agent and Triton X-100 Winsor II microemulsion as the extractant, separation of aluminium species in different pH solutions was achieved by microemulsion extraction. The formation of microemulsion, the conditions of extraction and determination of aluminium species were studied.

[Study of the sensitizing effects of surfactants on the determination of aluminum by air-acetylene flame atomic absorption spectrometry].

The sensitizing effects of ten surfactants, such as cetyl trimethyl ammonium bromide (CTMAB) and cetyl pyridinium chloride (CPC), on the determination of aluminum were studied. The results showed that the cationic surfactants in the experiment were good sensitizers for the determination of aluminum, and the sensitization time was about 3.0.