Shenguang Ge

Three-dimensional paper-based electrochemiluminescence immunodevice for multiplexed measurement of biomarkers and point-of-care testing

In this work, electrochemiluminescence (ECL) immunoassay was introduced into the recently proposed microfluidic paper-based analytical device (μPADs) based on directly screen-printed electrodes on paper for the very first time. The screen-printed paper-electrodes will be more important for further development of this paper-based ECL device in simple, low-cost and disposable application than commercialized ones. To further perform high-performance, high-throughput, simple and inexpensive ECL immunoassay on μPAD for point-of-care testing, a wax-patterned three-dimensional (3D) paper-based ECL device was demonstrated for the very first time. In this 3D paper-based ECL device, eight carbon working electrodes including their conductive pads were screen-printed on a piece of square paper and shared the same Ag/AgCl reference and carbon counter electrodes on another piece of square paper after stacking. Using typical tris-(bipyridine)-ruthenium (Ⅱ) - tri-n-propylamine ECL system, the application test of this 3D paper-based ECL device was performed through the diagnosis of four tumor markers in real clinical serum samples. With the aid of a facile device-holder and a section-switch assembled on the analyzer, eight working electrodes were sequentially placed into the circuit to trigger the ECL reaction in the sweeping range from 0.5 to 1.1 V at room temperature. In addition, this 3D paper-based ECL device can be easily integrated and combined with the recently emerging paper electronics to further develop simple, sensitive, low-cost, disposable and portable μPAD for point-of-care testing, public health and environmental monitoring in remote regions, developing or developed countries.

Paper-based chemiluminescence ELISA: lab-on-paper based on chitosan modified paper device and wax-screen-printing.

A novel lab-on-paper device combining the simplicity and low-cost of microfluidic paper-based analytical devices (μPADs) and the sensitivity and selectivity of chemiluminescence ELISA (CL-ELISA) for the high-throughput, rapid, stable and reusable point-of-care testing is presented here. Chitosan was used to modify μPADs to covalently immobilize antibodies on μPADs. Thus, sandwich CL-ELISA on μPADs can be easily realized for further development of this technique in sensitive, specific and low-cost application. The paper device was fabricated by a low-cost, simple, and rapid wax-screen-printing method. Using tumor markers and paper microzone plate as model, the application test of this paper-based CL-ELISA was successfully performed with a linear range of 0.1-35.0 ng mL(-1) for α-fetoprotein, 0.5-80.0 U mL(-1) for cancer antigen 125 and 0.1-70.0 ng mL(-1) for carcinoembryonic antigen. Since the cutoff values of the three tumor markers in clinical diagnosis are 25 ng mL(-1), 35 U mL(-1) and 5 ng mL(-1), the sensitivity and linear ranges of the proposed method were enough for clinical application. In addition, this lab-on-paper immunodevice can provide reproducible results upon storage at 4 °C (sealed) for at least 5 weeks. Ultimately, this novel chitosan modification and wax-screen-printing methodology for μPADs can be readily translated to other signal reporting mechanism including electrochemiluminescence and photoelectrochemistry, and other receptors such as enzyme receptors and DNA receptors for determination of DNA, proteins and small molecules in point-of-care testing.

Electrochemical biosensor based on graphene oxide-Au nanoclusters composites for l-cysteine analysis

In this paper, a linker-free connected graphene oxide/Au nanocluster (GO-Au NCs) composite was prepared under sonication through electrostatic interactions, and characterized by transmission electron microscope (TEM), atomic force microscope (AFM), ultraviolet-visible (UV-vis) and FT-IR spectrum. The morphological and structural characterizations evidence that the Au NCs can be efficiently decorated on the GO. The electrochemical investigations indicated that GO-Au NCs composite has an important role in the electrocatalytic activity towards the oxidation of L-cysteine (CySH). The GO-Au NCs composite modified electrode shows a large determination range from 0.05 to 20.0 μmol/L, a remarkably low detection limit is 0.02 μmol/L and low oxidation potential (+0.387). It was found that metal ions, carbohydrates, nucleotide acids and amino acids had no distinct effect on the determination of L-cysteine. In addition, the sensor has some important advantages such as simple preparation, fast response, good stability and high reproducibility. The direct determination of free reduced and total CySH in human urine samples has been successfully carried out without the assistance of any separation techniques.

A novel chemiluminescence paper microfluidic biosensor based on enzymatic reaction for uric acid determination.

In this work, chemiluminescence (CL) method was combined with microfluidic paper-based analytical device (μPAD) to establish a novel CL μPAD biosensor for the first time. This novel CL μPAD biosensor was based on enzyme reaction which produced H(2)O(2) while decomposing the substrate and the CL reaction between rhodanine derivative and generated H(2)O(2) in acid medium. Microchannels in μPAD were fabricated by cutting method. And the possible CL assay principle of this CL μPAD biosensor was explained. Rhodanine derivative system was used to reach the purpose of high sensitivity and well-defined signal for this CL μPAD biosensor. And the optimum reaction conditions were investigated. The quantitative determination of uric acid could be achieved by this CL μPAD biosensor with accurate and satisfactory result. And this biosensor could provide good reproducible results upon storage at 4°C for at least 10 weeks. The successful integration of μPAD and CL reaction made the final biosensor inexpensive, easy-to-use, low-volume, and portable for uric acid determination, which also greatly reduces the cost and increases the efficiency required for an analysis. We believe this simple, practical CL μPAD biosensor will be of interest for use in areas such as disease diagnosis.

Ultrasensitive electrochemical immunosensor based on Au nanoparticles dotted carbon nanotube–graphene composite and functionalized mesoporous materials

A facile and sensitive electrochemical immunosensor for detection of human chorionic gonadotrophin (hCG) was designed by using functionalized mesoporous nanoparticles as bionanolabels. To construct high-performance electrochemical immunosensor, Au nanoparticles (AuNPs) dotted carbon nanotubes (MWCNTs)-graphene composite was immobilized on the working electrode, which can increase the surface area to capture a large amount of primary antibodies (Ab(1)) as well as improve the electronic transmission rate. The as-prepared bionanolabels. composed of mesoporous silica nanoparticles (MCM-41) coated with AuNPs through thionine linking, showed good adsorption of horseradish peroxidase-labeled secondary anti-hCG antibody. Interlayer thionine was not only a bridging agent between MCM-41 and AuNPs but also an excellent electron mediator. The approach provided a good linear response range from 0.005 to 500 mIU mL(-1) with a low detection limit of 0.0026 mIU mL(-1). The immunosensor showed good precision, acceptable stability and reproducibility. Satisfactory results were obtained for determination of hCG in human serum samples. The proposed method provides a new promising platform of clinical immunoassay for other biomolecules.

Paper-based three-dimensional electrochemical immunodevice based on multi-walled carbon nanotubes functionalized paper for sensitive point-of-care testing

In this study, electrochemical immunoassay was introduced into the recently proposed microfluidic paper-based analytical device (μPADs). To improve the performance of electrochemical immunoassay on μPAD for point-of-care testing (POCT), a novel wax-patterned microfluidic paper-based three-dimensional electrochemical device (3D-μPED) was demonstrated based on the multi-walled carbon nanotubes (MWCNTs) modified μPAD. Using typical HRP-O-Phenylenediamine-H(2)O(2) electrochemical system, a sandwich immunoassay on this 3D-μPED for sensitive diagnosis of two tumor markers simultaneously in real clinical serum samples was developed with a linear range of 0.001-75.0 UmL(-1) for cancer antigen 125 and 0.05-50.0 ngmL(-1) for carcinoembryonic antigen. In addition, this 3D-μPED can be easily integrated and combined with the recently emerging paper electronics to further develop simple, sensitive, low-cost, disposable and portable μPAD for POCT, public health and environmental monitoring in remote regions, developing or developed countries.

Paper‐Based Electrochemiluminescent 3D Immunodevice for Lab‐on‐Paper, Specific, and Sensitive Point‐of‐Care Testing

Recent research on microfluidic paper-based analytical devices (μPADs) has shown that paper has great potential for the fabrication of low-cost diagnostic devices for healthcare and environmental monitoring applications. Herein, electrochemiluminescence (ECL) was introduced for the first time into μPADs that were based on screen-printed paper-electrodes. To further perform high-specificity, high-performance, and high-sensitivity ECL on μPADs for point-of-care testing (POCT), ECL immunoassay capabilities were introduced into a wax-patterned 3D paper-based ECL device, which was characterized by SEM, contact-angle measurement, and electrochemical impedance spectroscopy. With the aid of a home-made device-holder, the ECL reaction was triggered at room temperature. By using a typical tris(bipyridine)ruthenium-tri-n-propylamine ECL system, this paper-based ECL 3D immunodevice was applied to the diagnosis of carcinoembryonic antigens in real clinical serum samples. This contribution further expands the number of sensitive and specific detection modes of μPADs.

Three-dimensional paper-based electrochemiluminescence device for simultaneous detection of Pb2+ and Hg2+ based on potential-control technique.

In this work, a microfluidic paper-based analytical device (μPADs) has been proposed for simultaneous electrochemiluminescence (ECL) detection of lead ion (Pb(2+)) and mercury ion (Hg(2+)) based on oligonucleotide. The functionalized wax-patterned three-dimensional (3D) paper-based ECL device that can provide fast, cost-effective, simple, and sensitive detection for analysis was dependent on Pb(2+) and Hg(2+)-induced conformational change of DNA strands through the formation of G-quadruplex and T-Hg-T complex, respectively. The carbon nanocrystals (CNCs) capped silica nanoparticles (Si@CNCs) and Ru(bpy)(3)(2+)-gold nanoparticles (AuNPs) aggregates (Ru@AuNPs) were both used as ECL labels in our case. Structure characterization of Si@CNCs and Ru@AuNPs were obtained by the transmission electron microscope (TEM). Due to the different operational potentials of Si@CNCs and Ru@AuNPs, Pb(2+) and Hg(2+) coexisting in one paper working zone can be determined simultaneously with detection limits of 10 pM and 0.2 nM, respectively. Finally, this simple and cost-effective device was successfully applied for simultaneous detection of Pb(2+) and Hg(2+) in lake water and human serum samples, respectively.

Photoelectrochemical Lab-on-Paper Device Based on an Integrated Paper Supercapacitor and Internal Light Source

In this work, a photoelectrochemical (PEC) method was introduced into a microfluidic paper-based analytical device (μ-PAD), and thus, a truly low-cost, simple, portable, and disposable microfluidic PEC origami device (μ-PECOD) with an internal chemiluminescence light source and external digital multimeter (DMM) was demonstrated. The PEC responses of this μ-PECOD were investigated, and the enhancements of photocurrents in μ-PECOD were observed under both external and internal light sources compared with that on a traditional flat electrode counterpart. As a further amplification of the generated photocurrents, an all-solid-state paper supercapacitor was constructed and integrated into the μ-PECOD to collect and store the generated photocurrents. The stored electrical energy could be released instantaneously through the DMM to obtain an amplified (∼13-fold) and DMM-detectable current as well as a higher sensitivity than the direct photocurrent measurement, allowing the expensive and sophisticated electrochemical workstation or lock-in amplifier to be abandoned. As a model, sandwich adenosine triphosphate (ATP)-binding aptamers were taken as molecular reorganization elements on this μ-PECOD for the sensitive determination of ATP in human serum samples in the linear range from 1.0 pM to 1.0 nM with a detection limit of 0.2 pM. The specificity, reproducibility, and stability of this μ-PECOD were also investigated.

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.