Dopamine coated Fe₃O₄ nanoparticles as enzyme mimics for the sensitive detection of bacteria

Abstract

We report a simple and economical colorimetric bacterial sensing strategy with catalytic amplification using dopamine-capped iron oxide (Dop-Fe3O4) nanoparticles. These nanoparticles catalyse the oxidation of a chromogenic substrate in the presence of H2O2 into a green colored product. The catalytic activity of the nanoparticles is inhibited in the presence of bacteria, providing naked eye detection of bacteria at 104 cfu/mL and by spectrophotometric detection down to 102 cfu/mL.

On the formation of superoxide radicals on colloidal ATiO3 (A = Sr and Ba) nanocrystal surfaces

“…À is the catalytical decomposition of H 2 O 2 on the surface of titanium oxides 27 and oxidative coupling of alkyl radicals. 28 In most of these cases, the metal oxide surface needs to be activated prior to O 2 À formation by irradiation or suitable chemical treatments.…”

Development of Nanozymes for Food Quality and Safety Detection: Principles and Recent Applications

“…Mumtaz et al. () reported that dopamine‐modified Fe 3 O 4 NPs (Dop‐Fe 3 O 4 NPs) could efficiently capture bacterial cells in contaminated water, which simultaneously caused the remarkable inhibition of POD‐like activity of DA‐Fe 3 O 4 NPs. The bacterial concentration dependent inhibition of nanozyme activity of DA‐Fe 3 O 4 NPs enabled a quick and simple colorimetric assay of bacteria.…”

“…recently reported a colorimetric sandwich-type detection of foodborne pathogens based on the direct adsorption of bacterial cells onto POD-like hemin-concanavalin A hybrid nanoflowers and the separation by antibody-decorated magnetic beads. Mumtaz et al (2017) reported that dopamine-modified Fe 3 O 4 NPs (Dop-Fe 3 O 4 NPs) could efficiently capture bacterial cells in contaminated water, which simultaneously caused the remarkable inhibition of POD-like activity of DA-Fe 3 O 4 NPs. The bacterial concentration dependent inhibition of nanozyme activity of DA-Fe 3 O 4 NPs enabled a quick and simple colorimetric assay of bacteria.…”

Recent Progress of Nanozymes in the Detection of Pathogenic Microorganisms

“…[86] In addition, biomolecule functionalized Fe 3 O 4 NPs were also prepared to detect bacteria. For example, Mumtaz et al [87] exploited dopamine coated Fe 3 O 4 NPs to catalyze the oxidation of chromogenic substrates into green-colored products in the presence of H 2 O 2 . The oxidation process could be inhibited by bacteria, which was applied for the colorimetric detection of E. coli and B. subtilis.…”