One of the key avenues to improving global health is to diagnose and control infectious diseases, such as HIV and malaria. Viral-specific nucleic acid (NA) amplification (such as polymerase chain reaction, PCR) is often used to meet such a requirement; however, complicated blood sample preparation (NA purification) by sophisticated equipments inevitably restricts its applications for portable point-of-care diagnosis, especially in third-world countries. For instance, solid phase NA extraction methods require a multistep protocol (NA binding, washing and elution) with pipetting and centrifugation. Here, we developed a one-step and ultra-rapid (10 min) method for separation of proteins (PCR inhibitors) and NA and preconcentration of purified NA (>100-fold). By simply applying low DC electric field (1-3V) to pairs of electrodes patterned in microfluidic chips, the positively and negatively charged molecules (protein and NA, respectively) can be separated based on electrophoresis and then concentrated in different downstream chambers for NA amplification. The ratio of the absorbance at 260nm and 280 nm of purified samples can be >1.8 to meet the standard requirement of NA purity. In addition, PCR results can show better (or equal) sensitivity and selectivity than gold standard NA purification kits. The simple one-step process, together with portable and integratable features, makes this electrokinetic sample preparation a promising universal module for point-of-care diagnosis.
Project end date: 02/06/14