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Item Integrated DEP Assisted Detection of PCR Products With Metallic Nanoparticle Labels Through Impedance Spectroscopy(IEEE, 2022-10) Bhatt, GeetaElectrochemical 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.Item DNA-Based Sensors(Springer, 2017-12) Bhatt, GeetaSensing and detection for clinical diagnostic can be accomplished through various routes. Additionally what and how of sensing is critically optimized to meet individual needs. Diagnostics is carried out with various types of sensors out of which the electrochemical sensors are most used due to their unique ability to couple seamlessly with electronic circuitry. The DNA sensor is one of the most common types of sensors which is majorly deployed to perform expression monitoring, transcription profiling, etc., for example, the products developed by Affymetrix and Nanogen. This chapter is a consolidated review of the various aspects of DNA sensors, like the principle of detection, various ways of sensing and detection, applications of such DNA-based sensing. It looks at the various principles that are utilized for gene mapping like dielectrophoresis, polymerase chain reaction (PCR), real-time PCR or quantitative PCR (better known as q-PCR), hybridization, solid-phase PCR, droplet-based PCR, etc. It also reviews various sensing/detection strategies for sensing DNA like electrophoresis, impedance spectroscopy, colorimetric sensing, optical sensing and inertial sensing. The chapter provides a state-of-the-art review of basic techniques, sensing methodologies and applications for DNA-based diagnostics as carried out by industry.Item Dielectrophoresis assisted impedance spectroscopy for detection of gold-conjugated amplified DNA samples(Elsevier, 2019-06) Bhatt, Geeta; Bhatt, GeetaMolecular diagnostics have always been at the forefront of disease identification and control. Various approaches exist for carrying out molecular diagnostics through identification of genes or proteins and are largely deployed in the laboratories for testing; although there exist a wide possibility of refinement in these existing processes. In this respect, impedance-based detection methods have emerged as one of the most deployable methods primarily due to their robust and easy nature of measurement and easy integrability with microelectronic systems. Impedance assisted technique is very commonly used for detection of DNA and DNA amplification through PCR process although it does not really make a very specific identification system parallel to some other optical techniques; like TaqMan PCR, qPCR or Molecular beacon assisted detection of DNA sequences. In the current article, we have developed a novel strategy through nanoparticle labeling and dielectrophoretic manipulation which enhances the specificity of the identification of tagged-amplified DNA samples coming out of a PCR process. Impedance characteristics with respect to a various number of PCR cycles with a product consisting of nanoparticle-labeled DNA samples are measured with respect to increasing concentration. A significant differentiation is observed between the non-labeled non-specifically amplified DNA and the labeled specifically amplified sequence through varied impedance signals. The impedance characterization is performed at the instance where the analyte is mostly near the electrodes and this is accomplished through dielectrophoresis scheme. The different dielectrophoretic capture frequencies have been observed for non-labeled and labeled DNA products. This sensor has achieved a limit of detection of the range of 25–30 DNA copies. The eventual goal here is to integrate this strategy with microchip PCR to evolve a paradigm shift in the PCR microchip technology.