# Polyethyleneimine-Directed In Situ Gold Deposition on Gallium Nitride Nanoparticles for Enhanced Electrochemical Detection of Erythromycin

## TL;DR

This paper introduces a new nanomaterial that improves the electrochemical detection of erythromycin by combining gallium nitride and gold nanoparticles.

## Contribution

The novel contribution is the development of GaN-PEI-Au nanocomposites for enhanced erythromycin sensing.

## Key findings

- GaN-PEI-Au nanocomposites showed improved electrochemical performance for erythromycin detection.
- The material enabled a linear detection range of 5 nM–2 µM with high sensitivity and low detection limits.

## Abstract

Hybrid nanomaterials that integrate surface functionality, colloidal stability, and efficient electron-transfer pathways are highly attractive for improving electrochemical sensing performance. Herein, we report the fabrication and evaluation of polyethyleneimine-functionalized gallium nitride nanoparticles (GaN) decorated with gold nanoparticles (GaN-PEI-Au) as a tunable electrode modifier for enhanced differential pulse voltammetry (DPV) detection of erythromycin. Branched polyethyleneimine was employed as a multifunctional interfacial layer to stabilize GaN dispersions, introduce amine-rich surface chemistry, and enable in situ gold nanoparticle formation at the GaN-PEI. The optimized GaN-PEI-Au material exhibited high colloidal stability, a characteristic Au localized surface plasmon resonance in the ~520–525 nm range, and well-defined Au nanoparticles attached to the GaN surface. When applied as an electrode coating, GaN-PEI-Au significantly enhanced the erythromycin oxidation response compared to bare Au and GaN-PEI interfaces, consistent with synergistic increases in electroactive surface area and interfacial charge-transfer efficiency. Under optimized DPV conditions, GaN-PEI-Au-modified electrodes enabled quantitative erythromycin determination with a linear range of 5 nM–2 µM (R2 = 0.990), sensitivity of 1.32 × 10−3 µA nM−1, and a limit of detection of 52.5 nM, while maintaining stable baseline behavior during repeated scans. The reported GaN-PEI-Au nanocomposites represent a robust platform for sensitive electrochemical detection of pharmaceutical compounds.