Sample preparation for point of care molecular diagnostics of STIs

Abstract

Brunel DoCLab is part of the esti2 consortium developing electronic self-testing instruments for sexually transmitted infections using nucleic acid amplification testing (NAAT). A proprietary sample collection device has been designed to integrate directly with a microfluidic cartridge. Cell lysis was conducted using a chemical method and nucleic acid purification was done on an activated cellulose membrane. The microfluidic device incorporates passive mixing of the lysis-binding buffers and sample. Preliminary results have shown extraction efficiencies for this new membrane of 69% and 57% compared to the commercial Qiagen extraction method of 85% and 59.4% for 0.1ng/μL and 100ng/μL salmon sperm DNA spiked in phosphate buffered solution. Preliminary extraction experiments in the passive mixer cartridges with lysis and nucleic acid purification showed extraction efficiency around 80% of the commercial Qiagen kit. Isothermal amplification was conducted using thermophillic helicase dependant amplification. A low cost benchtop real-time isothermal amplification platform has been developed capable of running six amplifications simultaneously. Work to integrate sample collection, nucleic acid extraction and isothermal amplification is currently underway.