| Paper-based microfluidic devices (?PAD) have recently gained significant interest because of their advantages of low-cost, miniaturization portable, compatible and easy to operate. The main purpose of this study was to combine the paper-based chip with immunoassy, seeking a novel protein immobilization method. Nanoparticles were used on paper-based chip as antibody labels, establishing a new fluorescent immunoassy method with high sensitivity. This thesis is divided into two parts, the first part is the review, which summarized the property, application and antibody immobilization method of the paper-based chip. The second part is as follows:1. Plasma treatment of paper for protein immobilization on paper-based chemiluminescence immunodeviceA novel protein immobilization method based on plasma treatment of paper on the low-cost paper-based immunodevice was established in this work. By using a benchtop plasma cleaner, the paper microzone was treated by oxygen plasma treatment for 4 min and then the antibody can be directly immobilized on the paper surface. Aldehyde group was produced after the plasma treatment, which can be verified from the fourier transform infrared spectroscopy (FT-IR) spectra and x-ray photoelectron spectroscopy (XPS) spectra. By linked to aldehyde group, the antibody can be immobilized on the paper surface without any other pretreatment. A paper-based immunodevice was introduced here through this antibody immobilization method. With sandwich chemiluminescence (CL) immunoassay method, the paper-based immunodevice was successfully performed for carcinoembryonic antigen (CEA) detection in human serum with a linear range of 0.1-80.0 ng/mL. The detection limit was 0.03 ng/mL, which was 30 times lower than the clinical CEA level. Comparing to the other protein immobilization methods on paper-based device, this strategy was faster and simpler and had potential applications in point-of-care testing, public health and environmental monitoring.2. Paper-based laser-induced fluorescence immunoassay based on silica-coated quantum dots assisted signal amplification strategyIn this work, we firstly combined the laser-induced fluorescence immunoassay with ?PAD and effectively integrate silica-coated QDs (QDs@SiO2) assisted signal amplification strategy. Using a laser (1mW) as a light source, combined fiber optic and photomultiplier tube (PMT) to assemble into a laser-induced fluorescence detector. The power of laser light source is small, so background fluorescence in the paper substrate was declined. Silica is one of the proper inert materials for coating QDs due to its biocompatibility for impeding the leakage of heavy metal ions into the environment and reducing the toxicity of QDs. So CdTe QDs@SiO2 was used as effective signal amplification fluorescence label to improve the sensitivity. AFP was successfully detected in human serum with the detection limit of 0.38 pg/mL. This strategy improved the sensitivity and made contributions for simple, high-throughput, low-cost, rapid laser-induced fluorescence immunoassay on ?PAD.3. Paper-based microfluidic immunodevice based on upconversion fluorescent nanoparticlesIn this work, we combined the upconversion nanometerials with ?PAD. P NaYF4:Yb,Tm upconversion fluorescent nanoparticles (UCNPs) were used as antibody markers to establish a new fluorescence immunoassay method on ?PAD. Because upconversion nanometerials are excited with near-infrared (NIR) light, background fluorescence of paper substrate was avoided effectively. Previous studies have shown the strong ability of UCNPs to circumvent the problem of autofluorescence and/or scattering light because of the NIR-excitation nature, which considerably improves the robustness and sensitivity of fluorescence assays. The washing strategy with a ring-oven was used on the paper-based microfluidic immunodevice, which furtherly reduced the background signal of physical adsorption. This method was successfully realized the detection of the IgG and the detection limit was 3.3 pg/mL. Therefore, the combination of ?PAD with upconversion fluorescence assay is likely to afford a promising tool for a point-of-care test (POCT)... |
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