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Real-time Monitoring of Macromolecular Biosensing Probe Self-assembly and On-chip ELISA using Impedimetric Microsensors

Research paper by Faheng Zang, Konstantinos Gerasopoulos, Xiao Zhu Fan, Adam D. Brown, James N. Culver, Reza Ghodssi

Indexed on: 14 Mar '16Published on: 11 Mar '16Published in: Biosensors and Bioelectronics



Abstract

This paper presents a comprehensive study of the self-assembly dynamics and the biosensing efficacy of Tobacco mosaic virus-like particle (TMV VLP) sensing probes using an impedimetric microsensor platform. TMV VLPs are high surface area macromolecules with nanorod structures constructed from helical arrangements of thousands of identical coat proteins. Genetically modified VLPs express both surface attachment-promoting cysteine residues and FLAG-tag antibody binding peptides on their coat protein outer surfaces, making them selective biosensing probes with self-assembly capability on sensors. The VLP self-assembly dynamics were studied by the continuous monitoring of impedance changes at 100 Hz using interdigitated impedimetric microsensors. Electrical impedance spectroscopy revealed VLP saturation on impedance sensor surface in 8 hours with surface coverage of 68% in self-assembly process. The VLP-functionalized impedance sensors responded to 12 ng/ml − 1.2 μg/ml of target anti-FLAG IgG antibodies in the subsequent enzyme-linked immunosorbent assays (ELISA), and yielded 18%-35% total impedance increases, respectively. The detection limit of the target antibody is 9.1 ng/ml using the VLP-based impedimetric microsensor. These results highlight the significant potential of genetically modified VLPs as selective nanostructured probes for autonomous sensor functionalization and enhanced biosensing.

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