A Quantitative Free Convection DNA Amplifier

The Polymerase Chain Reaction (PCR) has been used extensively to amplify targeted nucleic acids for many applications in molecular biology and, increasingly, in medical diagnostics. Outlined in this paper is a PCR device which takes account of the advantages offered by free convection. The design is, in it fundamental format a time-wise isothermal well-based thermocycler. A temperature gradient induced across the well causes convection forces to circulate the sample through the required temperatures necessary for amplification. Quantitative amplification is demonstrated with real time measurements of SYBR Green I fluorescence within the free convective DNA amplifier. Amplification of an 86-bp fragment of the pGEM®-T vector (Promega) is performed in a 25μl volume in eight minutes. A 10-fold dilution series and methods for calculating effective cycle times are presented. Also detailed within this paper are PIV and thermal imaging results of the free convection cavity. This device presents an opportunity for the development of a practical and inexpensive gene-expression measurement system.