Design of paper based microfludic nano immuno_sensor using recombinant antibody fragments for detection of gastrin_glycine

Abstract

The principle of the assay is based on the biochemical interaction of antigen-antibody on the μPAD. UV-Vis spectrum of AuNPs showed that according to the Turkevich-Frens method we synthesized approximately 25 nm spherical nanoparticles . Also conjugation of scFv on GNPs was confirmed by red shift of SPR band of AuNPs after conjugation. Next, VL antibody immobilized on the paper surface by Adsorption and Covalent coupling interactions. The main objective of this work is to evaluate the potential of the recombinant antibodies (rAbs) to establish of immunoassay on paper analytical device in order to collect quantitative or semi-quantitative answers of G17-Gly peptide. For this purpose, first VL piece as the capturing antibody was immobiliz on the paper surface which identified the peptide at the end of the C-terminal. On the other hand the single-chain variable fragmen (scFv) piece as detection antibody was conjugated with AuNPs which connected to the N-terminal of the gastrin-glycine peptide . After of colour stains producing on the bioactive papers in the presence of different concentrations of G17-Gly the papers were imaged by a phone camera. Then images were analyzed with a written program by the matlab software for measuring of colour intensity. The results showed increases of color intensity by increases of peptide concentration with got linear relations could be used for identification and quantification of G17-Gly peptide by developed paper-based immunoassay. Conclusion The µPAD was successfully developed for uncomplicated, convenient, quick , and reliable detection of G17-Gly. This affordable tool is especially suitable for point-of-care detection of dengue in rural. A sensitivity, specificity, reproducibility, and stability for the diagnosis of G17-Gly was demonstrated. The tool shows the possibility to detect G17-Gly in the buffer, serum.