Electrokinetic sandwich assay and DNA mediated charge amplification for enhanced sensitivity and specificity

An electrical immuno-sandwich assay utilizing an electrokinetic-based streaming current method for signal transduction is proposed. The records the changes in current, first when a target molecule binds to capture probes immobilized on inner surface of silica micro-capillary, and then detection interact with bound molecules surface. difference signals these two steps constitute response assay, which offers better selectivity linear concentration dependent within range 0.2–100 nM. proof concept demonstrated by detecting different concentrations Immunoglobulin G (IgG) both phosphate buffered saline (PBS) spiked E. coli cell lysate. A superior specificity sandwich compared corresponding direct along limit 90 pM PBS. prospect improving sensitivity was theoretically analysed, indicated that charge contrast between probe plays crucial role determining signal. This aspect experimentally validated modulating zeta potential conjugating negatively charged DNA oligonucleotides. length conjugated varied from 5 30 nucleotides, altering ?9.3 ± 0.8 mV ?20.1 0.9 mV. measurements showed clear consistent enhancement as function lengths. results presented here conclusively demonstrate electric well further improvement. study therefore step forward developing highly selective sensitive electrokinetic assays possible application clinical investigations.