Gold Nanomaterial-Based Microfluidic Paper Analytical Device for Simultaneous Quantification of Gram-Negative...

Area of Science:

• Analytical Chemistry
• Environmental Science
• Nanotechnology

Background:

• Water quality monitoring requires reliable detection of bacterial and chemical contaminants.
• Existing methods can be costly, time-consuming, and unsuitable for resource-limited environments.
• Simultaneous detection of multiple contaminants is crucial for comprehensive water assessment.

Purpose of the Study:

• To develop a rapid, cost-effective microfluidic paper-based analytical device (μPAD) for simultaneous detection of Gram-negative bacteria and nitrite ions.
• To validate the sensor's performance in various water samples and compare it with commercial assays.
• To assess the potential of the developed μPAD for real-time water quality monitoring in diverse settings.

Main Methods:

• Functionalization of gold nanoparticles (AuNPs) with polymyxin for Gram-negative bacteria detection via aggregation-induced color change.
• Utilizing antiaggregation of AuNPs in the presence of nitrite ions (NO2-) and o-phenylenediamine (OPD).
• Smartphone-based colorimetric analysis of reaction products on the μPAD for quantitative detection.

Main Results:

• The μPAD demonstrated linear detection ranges of 5.0 × 10^2 to 5.0 × 10^5 CFU/mL for E. coli and 0.20 to 2.0 μmol/L for NO2-.
• Detection limits were 2.0 × 10^2 CFU/mL for E. coli and 0.18 μmol/L for NO2-.
• High selectivity was observed, with no interference from Gram-positive bacteria, and acceptable recovery rates in real water and urine samples.

Conclusions:

• The developed μPAD offers a rapid, selective, and cost-effective solution for simultaneous detection of Gram-negative bacteria and nitrite ions.
• The sensor's reliance on stable AuNPs enhances assay longevity and reduces costs compared to enzyme/antibody-based methods.
• This technology is well-suited for real-time water quality assessment, particularly in resource-limited settings.