Miniaturized PCR chips for nucleic acid amplification and analysis: latest advances and future trends

Zhang, Chunsun; Xing, Da

In order for a PCR microfluidic chip to have value in clinical diagnostics or genetic profiling analysis, it must be capable of accepting the crude biological samples (other than purified DNAs) as an analytical target, such as cells, total RNA, virus, whole blood, urine, sperm, or nasal aspirate (see Table 3 ). As seen from a wide range of biological samples being on-chip amplified and analyzed, the PCR chips could be used for broad applications including molecular diagnostics of diseases (10, 32, 43, 47, 60) , gene expression analysis (35, 71, 78, 92, 93) , forensics, environmental testing, food safety testing and biothreat sensing. For example, the PCR/LDR/hybridization chip reported by Hashimoto et al. has been used to detect low-abundant DNA mutations in gene fragments (K-ras) that carry point mutations with high diagnostic value for colorectal cancers (60) . The lowest mutant:widetype ratio that could be detected by this chip was up to 1:80, and the total assay time was 50 min, including 18.7 min for PCR, 8.1 min for LDR, 5 min for hybridization, 10 min for washing and 2.6 min for fluorescence scanning (60) . Since the sample preparation processes have been integrated on a single chip, along with the robust product detection techniques, the total analysis process can be completed within less than 25 min (less than 10 min for DNA extraction, 11 min for PCR and less than 3 min for injection, CE separation and detection) (27) . In addition, due to high integration and miniaturization of PCR chips, the biological sample and costly reagent consumption, as well as the possible contamination resulting from manual processes can be decreased. In principle, the PCR chips can be applied in any field where minute amounts of nucleic acid sample needs to be rapidly amplified and subsequently analyzed.