Shoumei Wang

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.

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.

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.

Molecularly imprinted polymer grafted paper-based multi-disk micro-disk plate for chemiluminescence detection of pesticide

The detection of pesticides has attracted considerable attention in numerous fields, such as environmental monitoring and food safety. Although traditional sensors for pesticides have been widely explored due to their high sensitivity and specificity, it is still challenging to develop a low-cost, portable, fast, and easy-to-use detection method for the public use at home or in the field. To address these challenges, herein, we report a novel paper-based molecular imprinted polymer (MIP)-grafted multi-disk micro-disk plate (P-MIP-MMP) for sensitive and specific chemiluminescence (CL) detection of pesticides through an indirect competitive assay using 2,4-dichlorophenoxyacetic acid (2,4-D) as a proof-of-concept analyte. The MIP-grafted paper disks were prepared by a simple in situ polymerization of MIP layer on the surface of cellulose fibers in paper. The quantification mechanism of this P-MIP-MMP is based on a competition between free 2,4-D and tobacco peroxidase (TOP) labeled 2,4-D and the enzyme catalyzed CL emission from the luminol-TOP-H2O2 CL system. At optimal conditions, this P-MIP-MMP can detect 2,4-D at the concentration of femtomolar level. This approach provided a powerful protocol for simple, low-cost, rapid, and high-throughput detection of pesticides in real samples with satisfactory results for use in areas such as food inspection and environmental monitoring.

Highly sensitive chemiluminescence immunoassay on chitosan membrane modified paper platform using TiO2 nanoparticles/multiwalled carbon nanotubes as label.

A highly sensitive chemiluminescence (CL) immunoassay was incorporated into a low-cost microfluidic paper-based analytical device (μ-PAD) to fabricate a facile paper-based CL immunodevice (denoted as μ-PCLI). This μ-PCLI was constructed by covalently immobilizing capture antibody on a chitosan membrane modified μ-PADs, which was developed by simple wax printing methodology. TiO2 nanoparticles coated multiwalled carbon nanotubes (TiO2/MWCNTs) were synthesized as an amplification catalyst tag to label signal antibody (Ab2). After sandwich-type immunoreactions, the TiO2/MWCNTs were captured on the surface of μ-PADs to catalyze the luminol-p-iodophenol-H2O2 CL system, which produced an enhanced CL emission. Using prostate-specific antigen as a model analyte, the approach provided a good linear response range from 0.001 to 20 ng/mL with a low detection limit of 0.8 pg/mL under optimal conditions. This μ-PCLI showed good reproducibility, selectivity and stability. The assay results of prostate-specific antigen in clinical serum samples were in good agreement with that obtained by commercially used electrochemiluminescence methods at the Cancer Research Center of Shandong Tumor Hospital (Jinan, Shandong Province, China). This μ-PCLI could be very useful to realize highly sensitive, qualitative point-of-care testing in developing or developed 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