Dual substrate sensor platform for rapid detection and differentiation of coliforms

Area of Science:

• Electrochemistry
• Biosensor Development
• Microbial Detection

Background:

• Existing sensor platforms for coliform detection require improvement for speed and specificity.
• Screen-printed carbon electrodes offer a basis for electrochemical biosensors.
• Accurate quantification of coliforms is crucial for public health and environmental monitoring.

Purpose of the Study:

• To modify and enhance a previously developed sensor platform for the rapid detection and quantification of coliforms.
• To introduce a new substrate for improved electrochemical signal generation.
• To establish a specific electrochemical signature for coliform identification.

Main Methods:

• Modification of a screen-printed carbon electrode sensor platform.
• Inclusion of L-alanyl-p-nitroanilide as a second substrate.
• Voltammetric analysis within a potential range of -600 to 400 mV.
• Incubation of bacterial samples for 3 hours.
• Measurement of electrochemical signals at a new potential of -113 mV.

Main Results:

• A distinct cathodic voltammetric peak was observed at -113 mV with the modified sensor.
• Coliforms at 10^6 CFU/mL produced significant electrochemical signals (920-988 μA) at -113 mV after 3 hours.
• Gram-positive bacteria at 10^6 CFU/mL did not produce a voltammetric peak at -113 mV, showing minimal background current (-80 to -200 μA).
• The voltammetric signals at the new potential were specific for coliforms.

Conclusions:

• The enhanced sensor platform provides rapid and specific detection of coliforms.
• The new voltammetric peak at -113 mV serves as a reliable indicator for coliform presence.
• This method offers a significant improvement for coliform quantification in various applications.