# Rapid SERS Assay for Determination of the Opioid Fentanyl Using Silver-Coated Sharply-Branched Gold Nanostars

## TL;DR

This paper presents a fast and sensitive method using nanostars to detect fentanyl in urine without sample preparation.

## Contribution

A high-throughput SERS platform using silver-coated gold nanostars for rapid fentanyl detection in urine.

## Key findings

- The SERS platform achieved a detection limit as low as 10.02 pg/mL for fentanyl in urine.
- Recovery values for spiked urine samples ranged from 92.5% to 102% with RSD under 10%.
- Optimal silver thickness of 45 nm maximized SERS enhancement on the nanostars.

## Abstract

Herein, we demonstrated a high-throughput surface-enhanced Raman scattering (SERS)-sensing platform for FNT detection in human urine without any sample preparation. The sensing platform was based on plasmonics-active silver-coated sharply branched gold nanostars (SGNS). The effect of silver thickness was investigated experimentally and theoretically, and the results indicated that SERS enhancement was maximum at an optimum silver thickness of 45 nm on the sharply spiked SGNS. The proposed high-throughput SERS platform exhibited ultrahigh SERS sensitivity and excellent enhancement uniformity for a model analyte, i.e., crystal violet. Moreover, the SERS-sensing platform demonstrated good detection sensitivity of FNT spiked in human urine samples with two differential linear responses ranging from 2 to 0.2 μg/mL and 0.1 μg/mL to 100 pg/mL, with a detection limit as low as 10.02 pg/mL. The spiked human urine samples show satisfactory recovery values from 92.5 % to 102 % with relative standard deviations (RSD) of less than 10 %. In summary, the high-throughput performance of the proposed microplate-based SERS platform demonstrated great potential for rapid low-cost SERS-based sensing applications.