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Enhanced Signal Amplification in a TLR-4 Biosensor Utilizing Ferrocene-Terminated Mixed Monolayers
摘要： A major challenge in effectively treating infections is to provide timely diagnosis of a bacterial or viral agent. Current cell culture methods require >24 hours to identify the cause of infection. The Toll-Like Receptor (TLR) family of proteins can identify classes of pathogens and has been shown to work well in an impedance-based biosensor, where the protein is attached to an electrode via a self-assembled monolayer (SAM). While the sensitivity of these sensors has been good, they contain a high resistance (>1 kΩ) SAM, generating relatively small signals and requiring longer data collection, which is ill-suited to implementation outside of a laboratory. Here, we describe a novel approach to increase the signal magnitude and decrease the measurement time of a TLR-4 biosensor by inserting a redox-active ferrocenyl-terminated alkane thiol into a mixed SAM containing hydroxyl- and carboxyl-terminated alkane thiols. The SAM formation and modification was confirmed via contact angle and X-ray photoelectron spectroscopy measurements, with TLR-4 immobilization demonstrated through a modified immunosorbent assay. It is shown that these TLR-4 biosensors respond selectively to their intended target, Gram-negative bacteria at levels between 100 and 105 lysed cells/mL, while remaining insensitive to Gram-positive bacteria or viral particles at up to 105 particles/mL. Furthermore, the signal enhancement due to the addition of ferrocene decreased the measurement time to less than one minute and has enabled this sensor to be used with an inexpensive, portable, handheld potentiostat that could be easily implemented in field settings.
关键词： TLR-4,Toll-Like Receptor biosensor,Gram-negative bacteria,ferrocene.,Mixed self-assembled monolayers
更新于2025-09-04 15:30:14
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Raman and Surface-Enhanced Raman Scattering for Biofilm Characterization
摘要： Bio?lms are a communal way of living for microorganisms in which microorganism cells are surrounded by extracellular polymeric substances (EPS). Most microorganisms can live in bio?lm form. Since microorganisms are everywhere, understanding bio?lm structure and composition is crucial for making the world a better place to live, not only for humans but also for other living creatures. Raman spectroscopy is a nondestructive technique and provides ?ngerprint information about an analyte of interest. Surface-enhanced Raman spectroscopy is a form of this technique and provides enhanced scattering of the analyte that is in close vicinity of a nanostructured noble metal surface such as silver or gold. In this review, the applications of both techniques and their combination with other bio?lm analysis techniques for characterization of composition and structure of bio?lms are discussed.
关键词： Raman spectroscopy,surface-enhanced Raman spectroscopy,biofilm,nanoparticles,bacteria
更新于2025-09-04 15:30:14