Abstract
This paper reports for the first time printed-circuit-board (PCB)-based label-free electrochemical detection of bacteria. The demonstrated immunosensor was implemented on a PCB sensing platform which was designed and fabricated in a standard PCB manufacturing facility. Bacteria were directly captured on the PCB sensing surface using a specific, pre-immobilized antibody. Electrochemical impedance spectra (EIS) were recorded and used to extract the charge transfer resistance (Rct) value for the different bacteria concentrations under investigation. As a proof-of-concept, Streptococcus mutans (S. mutans) bacteria were quantified in a phosphate buffered saline (PBS) buffer, achieving a limit of detection of 103 CFU/mL. Therefore, the proposed biosensor is an attractive candidate for the development of a simple and robust point-of-care diagnostic platform for bacteria identification, exhibiting good sensitivity, high selectivity, and excellent reproducibility.
Highlights
Bacteria comprise a ubiquitous type of microorganism, involved in numerous clinical, environmental, and industrial phenomena; indicative examples include infectious diseases, food and water safety, and insulin synthesis [1]
Streptococcus mutans strain MTCC890 was purchased from Microbial Type Culture Collection and Gene Bank (MTCC), Chandigarh, India
Non-specific binding on the sensor surface was minimized by bovine serum albumin (BSA), allowing the functionalized sensor to selectively bind with S. mutans
Summary
Bacteria comprise a ubiquitous type of microorganism, involved in numerous clinical, environmental, and industrial phenomena; indicative examples include infectious diseases, food and water safety, and insulin synthesis [1]. The detection (i.e., quantification range, limit of detection) and usability (i.e., time to result, cost) requirements for each case vary, but underpin in a similar manner all of them For this reason, a multitude of research groups around the world have been proposing various bacterial detection technologies as alternatives to laborious standard protocols such as bacterial culture. In all of the aforementioned cases though, the assay completion is laborious, requiring several sample preparation steps in order to achieve efficient quantification Optical quantification methods, such as surface plasmon resonance imaging (SPRi) have been reported, showing promising limits of detection in liquid culture media, but has yet to be demonstrated in bacterial multiplication-free systems [2]
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