Xiaoxue Ye

Enhanced photoelectrochemical immunosensing of cardiac troponin I based on energy transfer between N-acetyl-L-cysteine capped CdAgTe quantum dots and dodecahedral Au nanoparticles

An immunosensor was fabricated with an immobilized antibody for cardiac troponin I (anti-cTnI) on a photoresponsive composite material consisting of N-acetyl-L-cysteine capped CdAgTe quantum dots (NAC-CdAgTe QDs) and dodecahedral gold nanoparticles (AuNPs) stabilized by 1-(10-bromodecyl)-3-methylimidazolium bromide ionic liquid. Synthesized materials were characterized by TEM, SEM, UV-Vis, XRD, XPS, EIS, fluorescence, and photoelectrochemical method to confirm their morphology, elemental composition, and properties. The sensing element, anti-cTnI, was then covalently bound to the composite material coated on a glassy carbon electrode to complete the immunosensor, abbreviated as anti-cTnI(BSA)/NAC-CdAgTe QDs/AuNPs/GCE. Photocurrent was measured when the sensor was excited by a 405nm 100mW laser light. Optimal operating conditions, stability, reversibility, and reproducibility of the sensor have been studied. Performance of the aforementioned sensor was monitored with the photocurrent and the relative photocurrent variation, which is expressed as the changes in photocurrent upon the formation of antibody-antigen complex relative to the initial current measured in the unbound state of antibody. The experiment showed the relative photocurrent variation is directly proportional to the logarithm of cTnI concentration between 5.0pgmL-1 and 20.0ngmL-1 with a detection limit of 1.756pgmL-1 (S/N=3). Performance of the immunosensor in common interferents and clinical human serum samples was investigated, showing comparable to ELISA with good selectivity, accuracy, and precision.

Molecularly Imprinted Photo-electrochemical Sensor for Human Epididymis Protein 4 Based on Polymerized Ionic Liquid Hydrogel and Gold Nanoparticle/ZnCdHgSe Quantum Dots Composite Film

A novel ionic liquid, 3-{[{4-[((carbamoyl)amino)ethyl methacrylate]butyl} ((carbamoyl)amino)ethyl methacrylate]propyl}-1-ethenyl-1H-imidazol-3-ium bromide (CCPEimBr) functionalized with vinyl, amino, and methacrylate groups, was synthesized and characterized with 1H NMR, FTIR, and HPLC-MS techniques. CCPEimBr was adopted as the functional monomer to prepare a molecularly imprinted polymerized ionic liquid hydrogel film on a glassy carbon electrode surface for human epididymis protein 4 (HE4) sensing. Gold nanoparticles (AuNPs) and ZnCdHgSe QDs were incorporated into the imprinted film as photo-electric active materials. The photocurrent response was measured to investigate the sensing performance of the imprinted sensors toward HE4. The imprinted photo-electrochemical sensor shows excellent selectivity, sensitivity, stability, and accuracy for HE4 determination. Experimental conditions including incubation time and pH value for determining HE4 were optimized in this study. The photocurrent variation (ΔI) decreased with increasing HE4 concentration (cHE4), and it was linearly proportional to cHE4 varied from 25 pg mL-1 to 4.0 ng mL-1. The detection limit of the imprinted sensor for determining HE4 was estimated to be 15.4 pg mL-1 (S/N = 3). The imprinted photo-electrochemical sensor was used to determine HE4 in human serum samples accurately.

Sensitive immunosensing of squamous cell carcinoma antigen based on a nanocomposite of poly{3-amine-N-[3-(N-pyrrole)propyl]imidazole bromide} ionic liquid and gold nanoroots

Squamous cell carcinoma antigen (SCCA) is a good specific antigen for cancer diagnosis specifically for squamous cell carcinomas. In this study, 3-amine-N-[3-(N-pyrrole)propyl]imidazole bromide (APPIBr) ionic liquid was successfully synthesized and characterized by 1H NMR, HPLC-MS and FTIR. APPIBr ionic liquid is a unique functional material with a pyrrole moiety which can be polymerized by using electrochemical technique and an amine group for immobilizing biomolecules; thus, it is ideal for the fabrication of biosensors. Using chloroauric acid as precursor and N-dodecyl imidazole as functional monomer, gold nanoroots (AuNRs) were fabricated and characterized with TEM, SEM and XRD. An immunosensor was built on a glassy carbon electrode (GCE), through the steps of forming the poly(APPIBr)/AuNRs/GCE interface by electrodeposition of APPIBr, anti-SCCA immobilization, and several optimization steps to achieve a sensitive, accurate, precise, and selective anti-SCCA/poly(APPIBr)/AuNRs/GCE for the electrochemical immunosensing SCCA. It was found that poly(APPIBr)/AuNRs nanointerface can improve the sensing performance of the immunosensor. Under the optimized experimental conditions, there existed two linear regimes relating the peak current variation to the concentration of squamous cell carcinoma antigen in the range of 0.001-0.1ngmL-1 and 0.1-5.0ngmL-1. The detection limit was calculated to be 0.3pgmL-1. The developed sensor was demonstrated its capability in quantitative analysis of squamous cell carcinoma antigen in human serum with recoveries of 97.3%, 102.4% and 107.4%.

Sensing platform for neuron specific enolase based on molecularly imprinted polymerized ionic liquids in between gold nanoarrays

A molecularly imprinted electrochemical sensor for neuron specific enolase (NSE) was developed by electrochemical polymerizing ionic liquid, which was functionalized with pyrrole moiety, in between gold nanoarrays. A well-defined 3D structured gold nanoarray was fabricated on a glassy carbon electrode (GCE) surface by using template-assisted electrochemical deposition technique. 1-(3-mercaptopropyl)-3-vinyl-imidazolium tetrafluoroborate was self-assembled onto the surface of gold nanoarrays to produce active sites for anchoring the molecularly imprinted film. Subsequently, an electrochemical polymerization procedure was carried out in an aqueous solution containing 1,3-di(3-N-pyrrolpropyl)imidazolium bromine ionic liquid and neuron specific enolase (NSE). After removing NSE templates, a molecularly imprinted sensor was successfully fabricated. The sensor showed high selectivity and sensitivity towards NSE, produced a linear response in the concentration range from 0.01 to 1.0ngmL-1 and had a detection limit of 2.6pgmL-1 with an incubation time of 15min. The developed sensor was demonstrated successful in determining NSE in clinical serum samples.

A photoelectrochemical immunosensor based on gold nanoparticles/ZnAgInS quaternary quantum dots for the high-performance determination of hepatitis B virus surface antigen

ZnAgInS quaternary quantum dots were prepared using glutathione as the capped reagent. Gold nanoparticles (GNPs) were integrated with ZnAgInS QDs to provide a GNPs/ZnAgInS QDs nanocomposite. The morphological image, component and crystal structure of GNPs/ZnAgInS QDs were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). A glassy carbon electrode surface was coated with GNPs/ZnAgInS QDs nanocomposites to construct an interface for immobilizing the antibody of hepatitis B virus surface antigen (anti-HBsAg). By employing GNPs/ZnAgInS QDs as a photoactive element, a photoelectrochemical immunosensor for hepatitis B virus surface antigen (HBsAg) was developed. The results indicate that gold nanoparticles can dramatically enhance the photocurrent response of ZnAgInS QDs and thus improving the sensing performances of the immunosensor. The experimental conditions including incubation time, incubation temperature, and ascorbic acid concentration were optimized. The relative photocurrent decline [Ri = ΔI/I0= (I0 - I)/I0] shows a linear relationship to the logarithm of HBsAg concentration [lg(c, ng mL-1)] in the range from 0.005 to 30 ng mL-1. A detection limit of 0.5 pg mL-1 was obtained. The immunosensor shows excellent sensitivity, selectivity, stability and reproducibility. The HBsAg concentrations in clinical serum samples were also accurately determined with this new photoelectrochemical immunosensor.