Sensitivity and Response Time of Polyethyleneimine Modified Impedimetric Transducer for Bacteria Detection

Abstract

AbstractAn impedimetric transducer based on an interdigitated electrode array (IDEA) modified with polyethyleneimine was used to study interactions with bacteria present in a sample solution. Bacteria immobilization on the sensor surface affects the surface charge and produces changes in the superficial impedance. The sensor surface was chemically modified by layer‐by‐layer (LbL) method with oppositely charged polyelectrolyte layers by alternating polyethyleneimine (PEI) and poly(sodium 4‐styrenesulfonate) (PSS). Escherichia coli gram‐negative bacteria were employed as a model for sensitivity and response time evaluation. Bacteria were immobilized on IDEA with PEI‐PSS‐PEI multilayer taking into account the ability of PEI to react chemically with outer membrane compounds of gram‐negative bacteria and thus improve purely electrostatic interactions. Detection limit of the sensor was found to be as low as 101 cfu/mL in E. coli cultures with response time around 20 minutes. In order to introduce a biorecognition element by bacterial detection, the lectin Concanavalin A (ConA) was deposited on IDEA surface through PEI‐ConA interaction, achieving a detection limit of 104 cfu/mL. The strategies developed show the possibility to achieve highly sensitive and rapid detection of bacteria using IDEA transducers.