Imprinted Polydimethylsiloxane-Graphene Oxide Composite Receptor for the Biomimetic Thermal Sensing of Escherichia coli

Abstract

This work presents an imprinted polymer-based thermal biomimetic sensor for the detection of Escherichia coli . A novel and facile bacteria imprinting protocol for polydimethylsiloxane (PDMS) films was investigated, and these receptor layers were functionalized with graphene oxide (GO) in order to improve the overall sensitivity of the sensor. Upon the recognition and binding of the target to the densely imprinted polymers, a concentration-dependent measurable change in temperature was observed. The limit of detection attained for the sensor employing PDMS-GO imprints was 80 ± 10 CFU/mL, a full order lower than neat PDMS imprints (670 ± 140 CFU/mL), illustrating the beneficial effect of the dopant on the thermo-dynamical properties of the interfacial layer. A parallel benchmarking of the thermal sensor with a commercial impedance analyzer was performed in order to prove the possibility of using the developed PDMS-GO receptors with multiple readout platforms. Moreover, S. aureus , C. sakazakii and an additional E. coli strain were employed as analogue species for the assessment of the selectivity of the device. Finally, because of the potential that this biomimetic platform possesses as a low-cost, rapid, and on-site tool for monitoring E. coli contamination in food safety applications, spiked fruit juice was analyzed as a real sample. Reproducible and sensitive results fulfill the limit requirements of the applicable European microbiological regulation.

Deposition Methods for the Integration of Molecularly Imprinted Polymers (MIPs) in Sensor Applications

“…[75] Another benefit of this approach is the variety of readouts that could be employed using surfaces prepared with this technique, in fact these imprinted layers have been used with electrochemical, [7,69,73] thermal, [7,65,68,71] Raman, [66,67] and QCM [70,72,75] readout technologies. It should also be noted that by slightly varying the chemical composition of the substrate and stamp employed for the imprinting (Table 1), the sensitivity and selectivity of the sensor could be strongly affected, [7,76] thus leaving a great margin for improvement of such imprinted layers.…”

“…[182] Since the polymer film can be designed with several monomers and/or cross-linker molecules, the variation of one of mixture components can have a huge impact not only on the sensitivity of the sensor but also on the transducer used to convert a given signal. For this reason, these films have found application with several readout technologies such as: HTM, [76,97,183] EIS, [76] CV, [184,185] DPV, [186][187][188][189] QCM, [70,[190][191][192] GC-MS, [193,194] SPR, [195,196] APGC-MS/MS, [197] UHPLC-PDA, [198] UV-Vis. [199] Figure 8.…”

Advances, applications, and limitations of portable and rapid detection technologies for routinely encountered foodborne pathogens

“…This dual-mediated coupling approach significantly improved and enhanced the ability to capture bacterial pathogens in complex matrices without pre-treatment steps. Finally, an improved biomimetic thermal sensing of E. coli was recently reported by Arreguin-Campos et al (2022) , in which polydimethylsiloxane (PDMS) films were utilized as receptor layers and functionalized with graphene oxide (GO). The recognition and binding of the target onto the polymer resulted in a measurable change in temperature.…”

Graphene-Based Sensors for the Detection of Microorganisms in Food: A Review

“…Thus, it is the state of the art to know which types of microorganisms are present and can grow in food items over certain periods. Graphene sensors have been used to detect various targeted microorganisms in food constituents [ 51 , 52 , 53 , 54 ]. When the consumed food has a quantity of microorganisms that exceeds a certain limit, it becomes very dangerous.…”