Simultaneous Optical Detection of Multiple Bacterial Species Using Nanometer-Scaled Metal–Organic Hybrids

Abstract

This paper describes a simple strategy to identify bacteria using the optical properties of the nanohybrid structures (NHs) of polymer-coated metal nanoparticles (NPs). NHs, in which many small NPs are encapsulated in polyaniline particles, are useful optical labels because they produce strong scattered light. The light-scattering characteristics of NHs are strongly dependent on the constituent metal elements of NPs. Gold NHs (AuNHs), silver NHs (AgNHs), and copper NHs (CuNHs) produce white, reddish, and bluish scattered light, respectively. Moreover, unlike NPs, the color of the scattered light does not change even when NHs are aggregated. Introducing an antibody into NHs induces antigen-specific binding to cells, enabling the identification of bacteria based on light scattering. Multiple bacterial species adsorbed on the slide can be identified within a single field of view under a dark field microscope based on the color of the scattered light. Therefore, it is a useful development for safety risk assessments at manufacturing sites, such as those for foods, beverages, and drugs, and environmental surveys that require rapid detection of multiple bacteria.

Simultaneous Electrochemical Detection of Multiple Bacterial Species Using Metal–Organic Nanohybrids

“…These results demonstrate that the NH size is correlated with the size of the metal NPs. Considering the reduction potentials of the metal species used for NH production, it has been reported that AuCl 4 – ( E ○ =1.0 V vs SHE) is more easily reduced than Ag + ( E ○ =0.80 V) and Cu 2+ ( E ○ =0.34 V) . The reduction potentials of metal ions and the oxidation potentials of monomers are considered important factors in NH formation in the nanoreaction field.…”

“…− (E ○ =1.0 V vs SHE) is more easily reduced than Ag + (E ○ =0.80 V) and Cu 2+ (E ○ =0.34 V). 45 The reduction potentials of metal ions and the oxidation potentials of monomers are considered important factors in NH formation in the nanoreaction field. However, no clear correlation was observed between the reduction potential of the metal ions and the growth of metal NPs in the polymer matrix.…”

Electrochemical Evaluation of the Number of Viable Bacteria Using Carbon Electrode Chip

“…Bacterial cultures and all experiments were developed and managed in a Biosafety Level 2 laboratory in accordance with the appropriate safety regulations (WHO Laboratory Biosafety Manual). 6,7 The bacterial strain was cultured in an agar growth medium (E-MC35, Eiken Chemical, Japan) at 310 K for 18 h. A single colony was selected, placed in a liquid growth medium (5.0 mL), and incubated at 310 K for 6 h. The precipitate was dispersed in sterile ultrapure water and the E. coli K12 suspension concentration was adjusted to 3.6 © 10 11 CFU mL ¹1 .…”

“…4,5 In recent years, many studies have reported on the development of biosensors using novel materials and technologies. For highly sensitive and rapid detection of pathogenic bacteria, biosensors based on physical or chemical signals, such as light scattering, [6][7][8][9] fluorescence, 10,11 electrochemistry, [12][13][14][15] and piezoelectricity, 16 have been developed. In particular, electrochemical biosensors are particularly useful in fields where on-site testing is required because of their high sensitivity, rapid measurement, and ease of device miniaturization.…”

Holistic Prediction of AuNP Aggregation in Diverse Aqueous Suspensions Based on Machine Vision and Dark-Field Scattering Imaging

“…The common approach for building LSPR-based sensors relies on the scattering signal assay that detects the intensity and color of the scattering light of nanoparticles, which can be efficiently observed using dark-field microscopy (DFM). With the advantages of high sensitivity, high signal-to-noise, and high spatial and temporal resolution, DFM has been broadly used for quantitative analysis, , dynamic monitoring, , biological sensing, − and material performance evaluation − by observing the color change of the scattering light of nanoparticles in DFM images. However, due to the heterogeneity of the sample, the scattering information on a single nanoparticle cannot reflect the real distribution of the whole situation accurately.…”