Human Topoisomerase I interaction with DNA on flexible nylon substrate for malaria diagnosis

The study of interaction between human Topoisomerase I (hTopo I) and the appropriate sequences of DNA is shown, with the aim to realize a biosensor for malaria diagnosis. Topoisomerases alter the topological state of DNA by catalysing the breaking and rejoining of DNA strands1. The ligase activity is fundamental for our biosensing strategy, revealing the pathology. hTopo I was chosen as a model system for the Plasmodium analogous. The biosensor is a new flexible and easy to degrade biochip printed on nylon by dip-pen lithography (DPL). It is realized exploiting the high specificity of complementary ssDNA2 and hTopo I ligase activity. DPL operation needs ultra-low amounts of DNA (0.5 µL) to print thousands of spots with a tremendous reduction of expensive oligonucleotides consumption3. Defining the adequate spotting conditions was fundamental to favorite the injection of ssDNA sequence into a fibrous material like nylon. Laser scanning confocal microscopy (LSCM) allows to detect fluorescence from the deposited spots with high sensibility. The approach is ideal for fabricating cheap, flexible and easy to integrate biosensors.