Investigation of the Streptococcus mutans detection specificity and the real-time monitoring dental-biofilm formation of purple membrane-based photoelectric biochips

• Main Authors: Jun-Yuan Chen, 陳俊原
• Other Authors: Hsiu-Mei Chen
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/10306225571295551522

碩士 === 國立臺灣科技大學 === 化學工程系 === 105 === Bacteriorhodopsin (BR) is a retinal protein residing in Halobacterium salinarum purple membrane (PM). When illuminated, BR pumps a proton gradient across PM, leading to photocurrent generation. To improve the selectivity of antibody-PM and aptamer-PM composite sensor chips for Streptococcus mutans detection, which were previously developed by using the principles that PM photocurrent correlates linearly with illumination intensity and that bacteria scatter light, this study used glycine to block the residual active moiety of the homobifunctional crosslinker fabricated on PM-coated chips for recognition-element conjugation. For the detection of 106 CFU/mL bacteria, without prior glycine blocking, the antibody-PM chips exhibited not only a 53 % photocurrent reduction on S. mutans detection, but also 21% and 24% reductions for E. coli and L. acidophilus, respectively. On the other hand, with prior glycine blocking, the photocurrent reductions of the chips decreased to 8% and 7% on E. coli and L. acidophilus detections, respectively, indicating selectivity improvement of the antibody-PM chips. The effect of glycine blocking was less pronounced with the aptamer-PM chips because the photocurrent reductions decreased from 14% and 19% to only 12% and 15% for E. coli and L. acidophilus, respectively. Furthermore, a double-decked microfluidics device was designed and constructed to real-time monitor the formation of S. mutans biofilm on the substrate placed in the upper deck with a PM-coated photoelectric chip mounted in the lower deck. A diluted growth medium and an electrolyte buffer were injected into the upper and lower decks, respectively. The comparison of ITO glass modified with self-assembled monolayers with different terminal groups suggested that the hydrophobic and positively charged surface most easily caused S. mutans to form a mature 3D-strucutred biofilm. Moreover, the anti-biofilm peptides coated on the amine-terminated substrate effectively inhibited biofilm formation, with the inhibition efficiency increasing with their coating amounts. Therefore, the results confirmed the feasibility of real-time monitoring biofilm formation with the developed double-decked microfluidics.