Shaowei Wang

Electrochemiluminescence of blue-luminescent graphene quantum dots and its application in ultrasensitive aptasensor for adenosine triphosphate detection.

A simple approach based on exfoliating and disintegrating treatments for graphite oxide, followed by hydrothermal synthesis, was developed to prepare water-soluble graphene quantum dots (GQDs). The as-prepared GQDs exhibited bright blue emission under ultraviolet irradiation (∼365nm), and showed an excitation-independent photoluminescence feature. More importantly, a newly anodic electrochemiluminescence (ECL) was observed from the water-soluble GQDs with H2O2 as coreactant for the first time, and the ECL induced a strong light emission at a low potential (ca. 0.4V vs. Ag/AgCl). The ECL mechanism is investigated in detail. Employing SiO2 nanospheres as signal carrier, a novel SiO2/GQDs ECL signal amplification labels were synthesized based on which a ultrasensitive ECL aptamer sensor was proposed. Under the optimized experimental conditions, the proposed ECL aptamer sensor exhibited excellent analytical performance for adenosine triphosphate (ATP) determination, ranging from 5.0×10(-12) to 5.0×10(-9)molL(-1) with the detection limit of 1.5×10(-12)molL(-1). Due to the low cytotoxicity and excellent biocompatibility, GQDs are demonstrated to be an eco-friendly material as well as excellent ECL labeling agents for biosensor.

Multiplexed sandwich immunoassays using flow-injection electrochemiluminescence with designed substrate spatial-resolved technique for detection of tumor markers.

Convenient sensor array for simultaneous multi-analyte testing was increasingly needed in clinical diagnosis. A novel electrochemiluminescence (ECL) immunosensor array for the sequential detection of multiple tumor markers was developed by site-selectively immobilizing multiple antigens on different electrodes. Disposable indium tin oxide (ITO) glass array was employed as detection platform. With a sandwich-type immunoassay format, the amount of carbon dots coated silica (SiO(2)@C-dots) labeled antibodies increased with the increment of antigens in the samples. The ECL signal from different immunosensors was collected in turn by a photomultiplier (PMT) with the aid of a home-made potential transformer equiped with a home-made multiplexed-switch. Using carcino embryonic antigen (CEA), prostate specific antigen (PSA) and α-fetoprotein (α-AFP) as model analytes, the proposed immunoassay exhibited excellent precision and sensitivity. For all three analytes, the relative standard deviations (RSDs) for six times detection were lower than 7.1% and the detection limits were in the range of 0.003-0.006 ng mL(-1). The results for real sample analysis demonstrated that the newly constructed immunosensor array provided a rapid, simple, simultaneous multi-analyte immunoassay with high throughput, cost-effective and sufficiently low detection limits for clinical applications. Importantly, the novel individually addressable immunosensor array for multi-analyte immunoassay by introducing the ECL readout mechanism with the aid of the home-made potential transformer and multiplexed-switch could be a useful supplement to commercial assay methods in clinical chemistry.

Magnetic beads-based electrochemiluminescence immunosensor for determination of cancer markers using quantum dot functionalized PtRu alloys as labels

A novel electrochemiluminescence (ECL) immunosensor for sensitive detection of human chorionic gonadotrophin antigen (HCG-Ag) was constructed using CdTe quantum dot functionalized nanoporous PtRu alloys (QDs@PtRu) as labels for signal amplification. In this paper, nanoporous PtRu alloy was employed as the carrier for immobilization of CdTe QDs and antibodies. Primary monoclonal antibody to alfa-HCG antigen (McAb(1)) was immobilized onto the surface of chitosan coated Fe(3)O(4) magnetic nanoparticles (Fe(3)O(4)/CS MNPs) by glutaraldehyde (GA) as coupling agent. Then McAb(1) could be easily separated and assembled on the surface of indium tin oxide glass (ITO) owing to their excellent magnetic properties with external magnetic forces holding the MNPs. Due to signal amplification from the high loading of CdTe QDs, 4.67-fold enhancements in ECL signal for HCG-Ag detection was achieved compared to the unamplified method (single QDs as labels). Under optimal conditions, a wide detection range (0.005~50 ng mL(-1)) and low detection limit (0.8 pg mL(-1)) were achieved through the sandwich-type immunosensor. The novel immunosensor showed high sensitivity and selectivity, excellent stability, and good reproducibility, and thus has great potential for clinical detection of HCG-Ag. In particular, this approach presents a novel class of combining bifunctional nanomaterials with preferable ECL properties and excellent magnetism, which suggests considerable potential in a wide range of applications for bioassays.

Molecularly imprinted polymeric microspheres for determination of bovine serum albumin based on flow injection chemiluminescence sensor.

A novel flow injection chemiluminescence (FI-CL) sensor for the determination of bovine serum albumin (BSA) using molecularly imprinted polymeric microspheres (MIPMs) as recognition element is reported. The BSA-MIPM was synthesized by suspension polymerization in toluene, using methacrylic acid (MAA) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linker in the bovine serum albumin template molecule. Scanning electron microscope (SEM) was employed to characterize the surface morphology of the resultant imprinted microspheres. Molecular modeling was employed to simulate the possible recognition process of the MIPM. Then the synthesized BSA-MIPM was employed as recognition element by packing into flow cell to establish a novel FI-CL sensor. The chemiluminescence (CL) intensity was correlated linear with the concentration of BSA over the range of 1.0×10(-8) to 5.0×10(-6) g mL(-1) and the detection limit was 1.5×10(-9) g mL(-1). The relative standard deviation (RSD) for the determination of 1.0×10(-7) g mL(-1) BSA was 1.4% (n=11). The sensor is reusable and has a great improvement in sensitivity and selectivity for CL analysis. As a result, the new MIPM-CL sensor had been successfully applied to the determination of BSA in milk samples.

Facile and sensitive paper-based chemiluminescence DNA biosensor using carbon dots dotted nanoporous gold signal amplification label

A facile and sensitive chemiluminescence (CL) protocol for the detection of DNA on low-cost paper analytical device using simple, rapid wax-screen-printing method was developed by combining simply covalent modification and signal amplification in this work. The DNA sensor was prepared with N,N′-disuccinimidyl carbonate (DSC) to capture DNA by covalently immobilizing on μPADs, and carbon dots (C-dots) dotted nanoporous gold (C-dots@NPG) was employed for signal amplification label. After the sandwich-type DNA hybridization reaction, C-dots@NPG labeled signal DNA was captured on the DNA biosensor. In the presence of potassium permanganate, the radiative recombination of oxidant injected holes and electrons generated oxidant induced CL reaction of the C-dots@NPG and produced the CL signals. Under optimal conditions, the application of this paper-based DNA sensor was successfully performed with a linear range of 10−18 to 10−14 M and with a detection limit of 8.56 × 10−19 M for target DNA. The newly designed strategy not only provides a simple DSC modified platform to improve the immobilization of capture DNA or antibody, but also offers a high-efficiency C-dots@NPG signal amplification label to enhance the sensitivity, and thus will be a promising potential in public health and environmental monitoring.

Hand-drawn&written pen-on-paper electrochemiluminescence immunodevice powered by rechargeable battery for low-cost point-of-care testing.

In this paper, a pen-on-paper electrochemiluminescence (PoP-ECL) device was entirely hand drawn and written in commercially available crayon and pencil in turn for the first time, and a constant potential-triggered sandwich-type immunosensor was introduced into the PoP-ECL device to form a low-cost ECL immunodevice proof. Each PoP-ECL device contained a hydrophilic paper channel and two PoP electrodes, and the PoP-ECL device was produced as follows: crayon was firstly used to draw hydrophobic regions on pure cellulose paper to create the hydrophilic paper channels followed with a baking treatment, and then a 6B-type black pencil with low resistivity was applied for precision writing, as the PoP electrodes, across the hydrophilic paper channel. For further point-of-care testing, a portable, low-cost rechargeable battery was employed as the power source to provide constant potential to the PoP electrodes to trigger the ECL. Using Carbohydrate antigen 199 as model analyte, this PoP-ECL immunodevice showed a good linear response range from 0.01-200 U mL(-1) with a detection limit of 0.0055 U mL(-1), a high sensitivity and stability. The proposed PoP-ECL immunodevice could be used in point-of-care testing of other tumor markers for remote regions and developing countries.

Ultrasensitive chemiluminescence detection of DNA on a microfluidic paper-based analytical device

A novel microfluidic paper-based chemiluminescence (CL) analytical device (μPAD) with high-throughput, rapid, stable, reusable point-of-care (POC) testing and quantitative response for DNA was designed. Sodium periodate was used to modify μPAD to covalently immobilize capture DNA. The paper device was fabricated by a low-cost, simple, and rapid wax screen-printing method. The developed paper-based CL immunodevice, combined with a typical luminol–H2O2 CL system, showed excellent analytical performance for the detection of DNA. Moreover, gold nanoparticles for signal DNA immobilization were used for signal-on CL assay of target DNA, which greatly improved the sensitivity. This study shows the successful integration of the μPAD and the CL method to afford an easy-to-use, inexpensive, and portable alternative for POC monitoring.Graphical abstract

Ultrasensitive electrochemiluminescence detection of lengthy DNA molecules based on dual signal amplification

Aimed at the facile detection of lengthy DNA molecules, an easily operated sandwich-type electrochemiluminescence (ECL) DNA biosensor was constructed on a glassy carbon electrode (GCE) based on CdTe quantum dots coated hollow ZnO nanoparticles (CdTe-ZnO NPs)-S(2)O(8)(2-) ECL system in this work. To fabricate a high-performance protocol, the GCE surface was successively modified by graphene nanosheet (GS), carbon nanotube (CNT) and gold nanoparticles (AuNPs) to form AuNPs dotted CNT-GS composites (Au@CNT-GS) platform, which improved the electronic transmission rate as well as increased the amount of immobilized capture probe CMV-F (S(1)). For further ultrasensitive, stable and low-potential ECL detection, CdTe-ZnO NPs were synthesized, and employed to label signal probe T7 promoter (S(3)). Based on the hybridization effect, the immobilized capture probe S(1), target DNA and labeled signal probe S(3) formed a sandwich-type DNA complex, which produced the ECL emission in the presence with S(2)O(8)(2-) coreactant. Under optimal conditions, the DNA ECL biosensor showed a good linear range over 10(-14) M to 10(-19) M with a low detection limit of 0.61 × 10(-19) M. The proposed strategy demonstrates a reproducible, stable, and potent method that can be expanded to detect the genome which exists in living cells.

Flow injection electrochemiluminescence determination of L-lysine using tris(2,2′-bipyridyl) ruthenium(II) (Ru(bpy)32+) on indium tin oxide (ITO) glass

A flow injection electrochemiluminescence (FI-ECL) analysis method for the determination of L-lysine, in alkaline Na2CO3-NaHCO3 buffer solution, in the presence of tris(2,2′-bipyridyl) ruthenium(II) (Ru(bpy)32+) on indium tin oxide (ITO) glass was studied by conventional cyclic voltammetry. This method is based on the enhanced ECL of Ru(bpy)32+- L-lysine. Meanwhile, in order to overcome the drawbacks of conventional cells, a new ECL cell was designed. Under the optimal conditions, the enhanced ECL intensity was linearly related to the concentration of L-lysine in the range from 1.0 × 10−8 to 1.0 × 10−4 g mL−1 with a detection limit 1.43 × 10−9 g mL−1. The relative standard deviation (RSD) for the determination of 1.0 × 10−6 g mL−1L-lysine was 1.8% (n = 11). The possible mechanism is discussed. In this paper, the ECL behavior of Ru(bpy)32+ is studied on ITO glass, and the newly designed sensor is reusable, shows a great improvement in sensitivity and selectivity for ECL analysis, and can be successfully applied for amino acid analysis.

Electrochemical Sensor for Detection of Trichlorfon Based on Molecularly Imprinted Sol–Gel Films Modified Glassy Carbon Electrode

Thin films of molecularly imprinted sol–gel polymer with specific binding sites for trichlorfon were prepared, fixed on glassy carbon electrodes and used as recognition material. The binding characteristic of the imprinted films to trichlorfon was evaluated by equilibrium binding experiments; and, the morphology was studied by scanning electronic microscope. A novel electrochemical sensor for determination of trichlorfon was developed based on the reaction between trichlorfon and the molecularly imprinted sol–gel film, which was a modified glassy carbon electrode. The sensor displayed excellent selectivity and high sensitivity. The linear response range of the sensor was 10−8 –10−6xa0gxa0mL−1, and the limit of detection was 2.8xa0×xa010−9xa0gxa0mL−1. The relative standard deviation for the determination of 10−7xa0gxa0mL−1 trichlorfon was 3.5%. The sensor was applied to the determination of trichlorfon in vegetables with satisfactory results.