A highly sensitive SERS substrate based on a mesoporous Ag–TiO<sub>2</sub> thin film for the detection of dye molecules

Das, Sathi; Saxena, Kanchan; Mehta, Dalip Singh

doi:10.1039/d2ma00211f

Cited by 13 publications

(6 citation statements)

References 31 publications

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“…Further, Gram-negative P. aeruginosa exhibits distinct peaks at 937 and 1319 cm −1 Table 1. Assigned SERS Spectrum Peaks of R6G 35,36 Raman peaks (cm assigned for polysaccharides and nucleic acids of the bacterial cell wall.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

SERS Nanowire Chip and Machine Learning-Enabled Classification of Wild-Type and Antibiotic-Resistant Bacteria at Species and Strain Levels

Das

Saxena

Tinguely

et al. 2023

ACS Appl. Mater. Interfaces

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Antimicrobial resistance (AMR) is a major health threat worldwide and the culture-based bacterial detection methods are slow. Surface-enhanced Raman spectroscopy (SERS) can be used to identify target analytes in real time with sensitivity down to the single-molecule level, providing a promising solution for the culture-free bacterial detection. We report the fabrication of SERS substrates having tightly packed silver (Ag) nanoparticles loaded onto long silicon nanowires (Si NWs) grown by the metal-assisted chemical etching (MACE) method for the detection of bacteria. The optimized SERS chips exhibited sensitivity down to 10–12 M concentration of R6G molecules and detected reproducible Raman spectra of bacteria down to a concentration of 100 colony forming units (CFU)/mL, which is a thousand times lower than the clinical threshold of bacterial infections like UTI (105 CFU/mL). A Siamese neural network model was used to classify SERS spectra from bacteria specimens. The trained model identified 12 different bacterial species, including those which are causative agents for tuberculosis and urinary tract infection (UTI). Next, the SERS chips and another Siamese neural network model were used to differentiate AMR strains from susceptible strains of Escherichia coli (E. coli). The enhancement offered by SERS chip-enabled acquisitions of Raman spectra of bacteria directly in the synthetic urine by spiking the sample with only 103 CFU/mL E. coli. Thus, the present study lays the ground for the identification and quantification of bacteria on SERS chips, thereby offering a potential future use for rapid, reproducible, label-free, and low limit detection of clinical pathogens.

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Section: ■ Results and Discussionmentioning

confidence: 99%

SERS Nanowire Chip and Machine Learning-Enabled Classification of Wild-Type and Antibiotic-Resistant Bacteria at Species and Strain Levels

Das

Saxena

Tinguely

et al. 2023

ACS Appl. Mater. Interfaces

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“…The intensity of the Raman signal of a molecular vibration generally increases with increasing change of polarizability, 35 surging radiation source power, 36 rising concentration of analyte molecules, 37 and nature and magnitude of the surrounding plasmonic field (whenever applicable). 38 Here, NaMBA molecules were attached to the surfaces of AuNPs.…”

Section: Coffee-ring Formationmentioning

confidence: 99%

Single Phase Transition Leads to the Nanoparticle Deposition in an Evaporating Sessile Droplet

Paul,

Chattopadhyay

2023

J. Phys. Chem. C

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The ubiquitous ring stain formation, upon evaporation of a sessile droplet, is known to be driven by a capillary flow taking the dispersed particles toward the three-phase contact line (TPCL) for gradual deposition with a rapid acceleration of the flow in the final leg of drying. However, we report that the process is akin to phase transition, with particles depositing at the contact line in a short span of time and well before the complete drying of the droplet. We used surface-enhanced Raman spectroscopy (SERS) when aqueous droplets of sodium 4-marcaptobenoate-stabilized nanomolar plasmonic gold nanoparticles (NaMBA-AuNPs) were evaporated under ambient conditions. The Raman signals of the molecules were observed to have sharply increased in a short window of time that matched well with simultaneous digital photographing of the deposition. Higher initial AuNP concentrations led to faster phase transitions; however, the final concentration at the TPCL was about 13 μM for 25 nm AuNPs, irrespective of the initial concentrations studied. The time for phase transitions decreased with increasing particle size at a fixed initial AuNP concentration.

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“…The surface-enhanced Raman spectroscopy (SERS) technique offers enhanced Raman spectra utilizing the nanostructure of metallic nanoparticles [8][9][10]. In SERS, metallic nanoparticles provide a hotspot with an enormously high local electric field due to localized surface plasmon resonance (LSPR) condition.…”

Section: Introductionmentioning

confidence: 99%

Rapid identification of antimicrobial drug resistance strains of E-coli using SERS nanowire chip

Das

Saxena²,

Khezri

et al. 2023

Plasmonics in Biology and Medicine XX

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We have investigated the enhanced Raman spectra of AMR bacteria strains of E. coli using silver coated silicon nanowires SERS assay. Three different E. coli strains, E. coli CCUG17620, NCTC 13441, and A239, were detected using two different excitation laser wavelengths. We found stable and enhanced SERS spectrum using 785 nm laser as opposed to 532 nm. Future development of SERS-chip could offer a reliable platform for direct identification of the pathogen in bio-fluid samples at strains level.

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A highly sensitive SERS substrate based on a mesoporous Ag–TiO₂ thin film for the detection of dye molecules

Abstract: We present a fast, accurate, and molecular specific detection technique of dyes at an ultra-trace level using surface-enhanced Raman spectroscopy (SERS). A highly sensitive Ag - TiO2 thin film having...

Cited by 13 publications

References 31 publications

SERS Nanowire Chip and Machine Learning-Enabled Classification of Wild-Type and Antibiotic-Resistant Bacteria at Species and Strain Levels

SERS Nanowire Chip and Machine Learning-Enabled Classification of Wild-Type and Antibiotic-Resistant Bacteria at Species and Strain Levels

Single Phase Transition Leads to the Nanoparticle Deposition in an Evaporating Sessile Droplet

Rapid identification of antimicrobial drug resistance strains of E-coli using SERS nanowire chip

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A highly sensitive SERS substrate based on a mesoporous Ag–TiO2 thin film for the detection of dye molecules

Abstract: We present a fast, accurate, and molecular specific detection technique of dyes at an ultra-trace level using surface-enhanced Raman spectroscopy (SERS). A highly sensitive Ag - TiO2 thin film having...

Cited by 13 publications

References 31 publications

SERS Nanowire Chip and Machine Learning-Enabled Classification of Wild-Type and Antibiotic-Resistant Bacteria at Species and Strain Levels

SERS Nanowire Chip and Machine Learning-Enabled Classification of Wild-Type and Antibiotic-Resistant Bacteria at Species and Strain Levels

Single Phase Transition Leads to the Nanoparticle Deposition in an Evaporating Sessile Droplet

Rapid identification of antimicrobial drug resistance strains of E-coli using SERS nanowire chip

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Product

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A highly sensitive SERS substrate based on a mesoporous Ag–TiO₂ thin film for the detection of dye molecules