Ultra-Sensitive, Rapid and On-Site Sensing Harmful Ingredients Used in Aquaculture with Magnetic Fluid SERS.

Meizhen Zhang,Jingru Liao,Miao Zhang,Qian Yu,Xianming Kong,Alan X. Wang

doi:10.3390/bios12030169

Meizhen Zhang, Jingru Liao + Show 4 more

Open Access

https://doi.org/10.3390/bios12030169

Copy DOI

Abstract

The integration of surface-enhanced Raman scattering (SERS) spectroscopy with magnetic fluid provides significant utility in point-of-care (POC) testing applications. Bifunctional magnetic–plasmonic composites have been widely employed as SERS substrates. In this study, a simple and cost-effective approach was developed to synthesize magnetic–plasmonic SERS substrates by decorating silver nanoparticles onto magnetic Fe3O4 nanoparticles (AgMNPs), which function both as SERS-active substrates and magnetic fluid particles. The strong magnetic responsivity from AgMNPs can isolate, concentrate, and detect target analytes from the irregular surface of fish skin rapidly. We fabricate a microfluid chip with three sample reservoirs that confine AgMNPs into ever smaller volumes under an applied magnetic field, which enhances the SERS signal and improves the detection limit by two orders of magnitude. The magnetic fluid POC sensor successfully detected malachite green from fish with excellent selectivity and high sensitivity down to the picomolar level. This work achieves a label-free, non-destructive optical sensing approach with promising potential for the detection of various harmful ingredients in food or the environment.

Highlights

Instant and sensitive detection of harmful ingredients in the environment or food is critical for public health to prevent environmental diseases or food-borne illnesses
The magnetic–plasmonic AgMNPs were constructed via the assembly of Ag NPs onto the surfaces of Fe3O4 by electrostatic interaction
The MNPs used in this research were commercially available Fe3O4 powder, which is very cost-effective compared with laboratory-prepared materials

Summary

Introduction

Instant and sensitive detection of harmful ingredients in the environment or food is critical for public health to prevent environmental diseases or food-borne illnesses. The flexible SERS chip successfully detects pesticides from food samples with high sensitivity, and the cost-effective feature of paper shows potential for massive fabrication [19,20]. The magnetic–plasmonic composite and microfluidic chip are integrated to synergistically provide advanced properties in POC SERS sensors, which are well-suited for chemical detection and food safety monitoring [22–25]. The microfluid chip confines the magnetic–plasmonic composite into cascaded reservoirs with ever smaller volumes under an external magnetic field, which could concentrate the target analyte and further enhance the SERS signal, as shown in Scheme 1. The results indicate that the microfluid chip with AgMNPs as magnetic fluid carriers possesses good sensitivity and selectivity in food safety and shows great potential for practical POC application in real applications. The magnetic fluid chip was designed to maneuver the magnetic–plasmonic composite through the process of separation, concentration, and SERS detection.

SERS Measurement

Other Measurements

Construction and Characterization of AgMNPs

SERS Performance of the AgMNPs

Sample Enrichment Effect of the Magnetic Fluid Device