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

Zhang, Chunsun; Xing, Da

On-chip CE separation integrated with PCR. One of the most common components integrated with PCR on a single chip is CE. A hybrid DNA analytical chip that performs PCR in a silicon microheater and CE in a glass chip was first reported by Woolley et al. in 1996 (102) . Since then, a variety of chips with different degrees of functional integration have been reported (4) . Nowadays, the integrated PCR-CE chip is still a burgeoning research area (26, 27, (31) (32) (33) 35, 40, 43) . For example, Easley et al. proposed on-chip pressure injection for integration of IRmediated PCR amplification with CE separation (26) . It was reported that the total analysis time was 12 min, representing the fastest PCR-CE chip integration achieved to date. Within another integrated chip recently reported by Easley et al. (27) , nucleic acid purification through SPE, followed by PCR amplification and microchip CE amplicon separation and detection, was completed in less than 30 min. Huang et al. presented an integrated chip for DNA/RNA amplification, CE separation and on-line optical detection (40) . This work has two important improvements: (i) The sample template can be DNA or RNA and (ii) using a buried optic fiber instead of the LIF to optically detect the PCR products can avoid the bulky optical detection apparatus. Another notable work is the development of four-lane PCR-CE chip that is capable of performing multiple (RT-) PCR-CE analyses in parallel (31, 35) . Recently, Prakash and Kaler reported an integrated PCR-CE chip that performed nine PCR reactions simultaneously in separate chambers and then sequentially analyzed the PCR product from each chamber by CE (33) . Those works may represent the development trend of the future PCR-CE chips: high analytical speed, high functional integration without the need for the external bulky equipments and improved parallelism.