Besides functioning as genetics information carrier, DNA has been demonstrated to be a powerful sensing tool in nanotechnology because of specific base pairing and interactions with small molecules. During the past decades, thermodynamics of DNA hybridization have been carefully characterized; in the meantime, cost and productivity of oligo synthesis have dramatically dropped and increased by several orders of magnitude, respectively. These allow DNA-based bio-sensing being predictable and affordable, which has wide applications in areas of disease diagnosis, forensic appraisal, food and environmental monitoring, etc.

DNA mutation and RNA abnormal expression level serve as the indicators of genetic diseases which are the most serious threaten to human health; whilst monitoring of tox...[ Read more ]

Besides functioning as genetics information carrier, DNA has been demonstrated to be a powerful sensing tool in nanotechnology because of specific base pairing and interactions with small molecules. During the past decades, thermodynamics of DNA hybridization have been carefully characterized; in the meantime, cost and productivity of oligo synthesis have dramatically dropped and increased by several orders of magnitude, respectively. These allow DNA-based bio-sensing being predictable and affordable, which has wide applications in areas of disease diagnosis, forensic appraisal, food and environmental monitoring, etc.

DNA mutation and RNA abnormal expression level serve as the indicators of genetic diseases which are the most serious threaten to human health; whilst monitoring of toxic heavy metal ions is important for drinking water. Many mature sensing techniques suffer from various limitations such as bulky equipment, complex preparation process, or low performance, making them unfavorable for point-of-care (POC) use. In this thesis, aiming at developing high performance platforms for POC applications with features of simple-operation, miniaturized-structure and low-cost, several approaches or improvements have been investigated.

Taking advantage of surface resonance effect, a low-cost, miniaturized and high throughput “peak-tracking chip” (PTC) has been designed and fabricated as an alternative to existing SPR technique, with the former more suitable for POC application. To simplify preparation process, immobilization-free strategies were studied. As the first trial, hydrolysis probe modified with multiple redox groups was designed and synthesized, aiming at improving sensitivity of E-qPCR approach proposed by our group. To further simplify operation, isothermal process has been investigated instead of thermal cycle process. An enzyme-assisted target-recycling (EATR) approach has been designed. Through probe design and target modification, false-positive issue in SNP detection has been effectively solved. Finally, elimination of protein-based enzyme was adopted to achieve higher robustness and reproducibility. Taking advantage of self-hydrolysis DNAzyme, a DNA dendritic self-assembly assisted mercury ion detection method has been developed, and improvement for leakage suppression has been studied.