Poly (Sulfobetaine methacrylate -b- Methacrylic acid) Grafting to Poly(dimethylsiloxane) Substrate for Yersinia Pestis Optical Detection in Whole Blood

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We successfully fabricated patterned PDMS sustrates with PMAA and PSBMA block copolymer brush which use RAFT then grafting to the surface by Click reaction in this experiment. The results show that we have the polymer brush grafts to patterned PDMS sustrates in an aspect ratio of 1:1.5 which one dimension pillar structure grating width is 500nm and 1µm. Use AFM to investigate the height relationship with other factors of polymer brush. XPS and FT-IR to analyze the constitution of the surface. Subsequently, we use surface modification techniques with anti-body in order to capture Yersinia pestis by means of applying EDC/NHS reaction to combined carboxylic acid functional group of PMMA with Protein G and Anti-Yp (F1-MoAb). Fulfilling all the vacancy with BSA to change the surface with anti-fouling property, and then fully washed and test with Yersinia pestis. The detection method theory utilizes laser energy loss due to grating diffraction. The sample concentration of 0 CFU/ml -106 CFU/ml is determined by using optical microscope to analysis fluorescence intensity of modified patterned polymer brush combined with Yersinia pestis. The block copolymer unit is prepared and graft to PDMS substrates. Polymer brushes tested that the sensitivity of PDMS-PSBMA-b-PMAA in the presence of the laser in human blood was superior to other substrates. It shows better sensitivity to Yersinia pestis and more than 99% anti-fouling ability of leukocytes. The results showed that higher concentration of Yersinia pestis, lower intensity the laser diffraction we get. The sensitivity could reach a maximum concentration of 7.5×10^1 CFU/ml which laser energy loss is approximately 10%. However, the fluorescence of the Yersinia pestis could not be detected by optical microscope, indicating the sensitivity of the laser detection is higher than optical microscope fluorescent detection method. The modificated PDMS with pillar width 500nm linear regression has the slope 0.828 meaning the better detection sensitivity for different concentrations of Yersinia pestis, and showed r2 0.9738. It will be considered a revolutionary tool for fast detection of Yersinia pestis.