A Self-Addressing SPR Sensing Platform with Reusability and its Applications on DNA Computation

• Main Authors: Tsung-Yao Chang, 張宗堯
• Other Authors: 林啟萬
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/79418574132746421723

碩士 === 臺灣大學 === 醫學工程學研究所 === 95 === We proposed a SPR-based microfluidic diagnostic platform with reusability in room temperature. The fabrication processes of this chip system are firstly to immobilize several sequence ssDNA probes on different gold spots. And then we would use the chip to collect the complementary sequence ssDNA probes that have chemically conjugated to different IgGs by Sulfo-SMPB which can links thiol group labeled on ssDNA and amine group existed on IgG.. After the DNA hybridization, we would inject various antibodies to that can react with immobilized IgGs. The repeatable and auto-addressing abilities are based on annealing and denaturing of the hydrogen bond between dsDNA. In this research, we have analyzed the IgG-ssDNA molecule from the concentration of 10 ng/ml~200 ng/ml. Besides, we also examined the efficiency, reproducibility, specificity and repeatability of this platform. We then proved that the intensity change caused by non-specific binding is about 10 percent after injecting BSA to block the non-specific absorption. Furthermore, results have shown that the fabricated platform can be reused for over 10 times. DNA computation has shown its feasibility for mathematical and biomedical applications. It would thus allow embedded intelligence for diagnosis, single nucleotide polymorphism (SNP) detection, amplification, encryption and drug delivery etc. However, it still suffers from several practical limitations, which include time-consuming, lack of reusability and miniaturization. In order to further improve current status of DNA computation, we incorporated this platform for the detection on the DNA array chip to solve a 3-clause satisfiability (SAT) problem with 3 variables of x, y and z. Each variable is defined by a 15-nt single strand DNA (ssDNA) which is immobilized on one spot of the gold surface. We further defined SPR reflective intensity changes 0, 0.2 and 2 A.U. caused by changes of molecular weight change on surface as Boolean signals False, True and None, respectively. Moreover, False signal represents a positive hybridization reaction via the hydrogen bond that binds the complementary ssDNA-IgG. And True signal represents the hybridization reaction that binds the complementary ssDNA-IgG-Antigen which can result in a much larger intensity change so that can make sure that we are able to distinguish different Boolean signals by different intensity changes. For a SAT problem of F=(XF∪YT) ∩(XT∪ZF) ∩(YT∪ZT), there are 8 possible answers. Therefore, we established a 3-spot array as a set which is immobilized sequence of x, y and z. After one calculation, we read out the solution of this set and then regenerate it by injecting 0.05 N sodium hydroxide solution.. Comparing to previous DNA computers which required days for a calculation, our proposed computational platform has significantly improved in time efficiency, chip reusability and realtime measurement for feasibility study.