Enhanced Signal Amplification in a Toll-like Receptor-4 Biosensor Utilizing Ferrocene-Terminated Mixed Monolayers.
Robert M MayallMargaret Renaud-YoungErin GawronSamantha LuongStephen E CreagerViola I BirssPublished in: ACS sensors (2018)
A major challenge in effectively treating infections is to provide timely diagnosis of a bacterial or viral agent. Current cell culture methods require >24 h 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 alkanethiol into a mixed SAM containing hydroxyl- and carboxyl-terminated alkanethiols. 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 1 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 1 min and has enabled this sensor to be used with an inexpensive, portable, hand-held potentiostat that could be easily implemented in field settings.
Keyphrases
- toll like receptor
- inflammatory response
- nuclear factor
- label free
- immune response
- high resolution
- gold nanoparticles
- sensitive detection
- gram negative
- sars cov
- primary care
- induced apoptosis
- cell cycle arrest
- electronic health record
- magnetic resonance imaging
- computed tomography
- single molecule
- cell death
- signaling pathway
- nucleic acid
- endoplasmic reticulum stress
- amino acid
- dual energy
- antimicrobial resistance
- solid state
- quality improvement
- electron transfer