Integrated DEP Assisted Detection of PCR Products With Metallic Nanoparticle Labels Through Impedance Spectroscopy

Electrochemical impedance spectroscopy (EIS) is gaining immense popularity in the current times due to the ease of integration with microelectronics. Keeping this aspect in mind, various detection schemes have been developed to make impedance detection of nucleic acids more specific. In this context, the current work makes a strong case for specific DNA detection through EIS using nanoparticle labeling approach and also an added selectivity step through the use of dielectrophoresis (DEP), which enhances the detection sensitivity and specificity to match the detection capability of quantitative polymerase chain reaction (qPCR) in real-time context as compared to the individually amplified DNA (Liu et al., 2008). The detection limit of the proposed biochip is observed to be 3-4 PCR cycles for 582 bp bacterial DNA, where the complete procedure of detection starts in less than 10 min. The process of integrated DEP capture of labeled products coming out of PCR and their impedance-assisted detection is carried out in an in-house micro-fabricated biochip. The gold nanoparticles, which possess excellent optical, chemical, electronic, and biocompatibility properties and are capable of generating lump-like DNA structure without modifying its basic impedance signature are introduced to the amplified DNA through the nanoparticle labeled primers.