Whole-Cell Bacterial Detection Using a Versatile Localized Surface Plasmon Resonance Biosensing Platform

Bacterial sensing is gaining lots of interest in the scientific community as well as health and food industries due to its profound impact in human health. With the worldwide burgeoning drug resistance among bacteria, the same bacterial infection now becomes more difficult and costly to treat. The current gold standard bacterial diagnostic methods suffer from being slow, typically several days to a week for infection identification, which unintentionally promotes the use of wide-spectrum antibiotics as an initial treatment, prompting the multidrug resistance crisis. To address this issue, various types of biosensors have been developed; however, it is rather challenging to be rapid, sensitive, selective, affordable, easy to operate, and to have a clinically relevant dynamic range. Therefore, achieving all aforementioned merits simultaneously is going to be the central focus of biosensor development.

The research presented here describes the development of a versatile whole-cell bacterial sensing platform and its applications to detect pathogens using localized surface plasmon resonance (LSPR) spectroscopy. Specifically, Pseudomonas aeruginosa and Acinetobacter baumannii were pulled down on the sensor surface using a Pseudomonas- specific aptamer and an Acinetobacter-specific siderophore, respectively. The whole-cell bacterial sensing platform developed in this work exhibits (i) rapid detection (~3 h) with minimal sample preparation, (ii) extraordinary sensitivity – down to the level of a singlePseudomonas aeruginosa cell and 80 Acinetobacter baumannii cells, (iii) a broad, yet clinically relevant, linear range (10 – 106 cfu mL-1), (iv) excellent selectivity over other tested bacteria, (v) versatile detection (simply switch pathogen specific-affinity reagents), and (vi) long shelf-life (2 weeks to 2 months) when stored in ambient conditions. The whole-cell bacterial sensor represents an important advance in pathogen diagnostics. With further optimization of its sensing performance and extension of its sensing capacity, this bacterial sensor could be a valuable addition to the existing diagnostic tools in both healthcare and food industries.