Crystals (Apr 2024)

Analysis and Modification of a Colorimetric Nanosensor for Rapid Detection of <i>Escherichia coli</i> in Water

  • Sarah Stabler,
  • Ruby Anne Lang,
  • Amro El Badawy,
  • Marie Yeung,
  • Jean Lee

DOI
https://doi.org/10.3390/cryst14040386
Journal volume & issue
Vol. 14, no. 4
p. 386

Abstract

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This research analyzed the mechanisms of work and modified a colorimetric nanosensor to make it more cost-effective for the detection of Escherichia coli (E. coli) in water. The base nanosensors modified herein rely on a competitive binding detection mechanism, where positively charged gold nanoparticles coated with polyethyleneimine (PEI-AuNPs) preferably bind to negatively charged E. coli in the presence of β-galactosidase (β-Gal) enzymes and chlorophenol red β-d-galactopyranosides (CPRG). The positive surface charge of the nanoparticle, rather than nanoparticle composition or type of chemical coating on its surface, was hypothesized herein as the governing factor for the nanosensor functionality. Thus, positively charged nanoparticles and polymers were tested as potential alternatives for gold nanoparticles for detecting E. coli. Positively charged silver and iron oxide nanoparticles coated with branched PEI detected E. coli as low as 105 and 107 colony-forming units per milliliter (CFU/mL), respectively. Furthermore, the branched PEI polymer itself (without nanomaterial) detected E. coli at 107 CFU/mL. These findings suggest that the positive charge, rather than the nanoparticle type was likely responsible for the detection of E. coli using the competitive binding approach. Therefore, other types of recyclable and cost-effective nanomaterials and polymers can be developed for E. coli detection using this rapid colorimetric sensing technique.

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