# Molecularly Imprinted Polymer-Based Electrogenerated Chemiluminescence Sensor for Sensitive and Selective Fentanyl Detection

## TL;DR

A new sensor using molecularly imprinted polymers detects fentanyl with high sensitivity and selectivity.

## Contribution

A novel MIP-based ECL sensor for ultrasensitive fentanyl detection with optimized fabrication and specificity.

## Key findings

- The sensor achieved a detection limit of ∼1 μM (3.4 ng in 10 μL).
- It showed three linear response regions spanning 1.0–70.0 μM fentanyl.
- The sensor demonstrated high reproducibility and specificity against similar compounds.

## Abstract

The escalating prevalence of fentanyl, a highly potent
synthetic
opioid responsible for rising overdose fatalities and public health
crises, underscores the critical need for sensitive and selective
detection methodologies. Herein, we report a molecularly imprinted
polymer (MIP)-based electrogenerated chemiluminescence (ECL) sensor
for ultrasensitive and selective quantification of fentanyl. The sensor
was fabricated by electropolymerizing 4-aminobenzoic acid (4-ABA)
on a glassy carbon electrode (GCE) in the presence of fentanyl as
the template, followed by template elution to yield recognition nanocavities
within the MIP film. ECL signal transduction was achieved through
the anodic coreactant pathway, wherein fentanyl (as the coreactant)
bound within the MIP cavities reacted with solution-phase [Ru­(bpy)3]2+ (as the ECL emitter) in phosphate buffer (pH
7.5) during anodic scans from 0 to 1.60 V vs Ag/AgCl (3.0 M KCl).
Critical fabrication and operational parameters, including electropolymerization
cycles, template concentration and molar ratio to the monomer, elution
conditions, and rebinding duration, were systematically optimized.
Density functional theory and density of states investigations guided
elution solvent selection and elucidated favorable fentanyl–polymer
interactions, verifying the sensor’s specificity toward fentanyl
over five common structurally similar interferents. Under optimized
conditions, the MIP-ECL sensor exhibited a limit of detection of ∼1
μM (S/N = 3), equivalent to 3.4 ng of fentanyl using 10 μL
solution, with three distinctive linear regions spanning 1.0 to 6.0,
6.0 to 40.0, and 40.0 to 70.0 μM. Additionally, the sensor demonstrated
high reproducibility and stability, positioning it as a promising
platform for rapid forensic analysis of illicit fentanyl.