Development of a compact disk type microfluidic chip based on DNA hybridization for phenylketonuria screening

Objective To develop a phenylketonuria (PKU) screening method based on a compact disk (CD) type microfluidic chip capable of generating reciprocating flow within the microchannels that facilitate rapid DNA hybridization. Methods This microfluidic device consists of a two-layer structure: a polydimethylsiloxane (PDMS) top layer containing 12 DNA hybridization microchannels, and a bottom glass layer with immobilized hydrogel conjugated DNA arrays. The DNA arrays included R243Q, V245V and the blank control probes. When the CD device was spun, the PCR products were driven into the hybridization channel by centrifugal force. When the rotation of the CD device was stopped, capillary force pulled the PCR products solution to flow back to the channel. After the on-chip hybridization, the hybridization signals were captured on a fluorescence microscope. The specificity, detection limitation and reproducibility of this device were evaluated. Thirty DNA samples from pregnant women with suspected PKU were detected by this device.Then the results were compared with DNA sequencing results. Results With the compact disk type microfluidic chip, the hybridization time could be reduced to 15 min, sample consume could be as low as 1. 5 μl and the detection limitation was 0. 7 ng/μl. With the chip based method, samples of PKU patients and healthy controls were detected and the results were consistent with DNA sequencing results. Five different batches of chips and five micro-channels of each chip were selected to test one PKU patients with V245V mutation. All the results were positive, indicating good reproducibility. Four cases of V245V mutation and 1 case of R243Q mutation were found in 30 suspected PKU carried pregnant women. Conclusion The compact disk microfluidic device has advantages of simple, rapid and highly sensitive, thus is well suited to PKU screening. Key words: Phenylketonuria; Phenylalanine hydroxylase; Microfluidic analytical techniques; Nucleic acid hybridization