Filter paper based SERS substrate for the direct detection of analytes in complex matrices.

Area of Science:

• Analytical Chemistry
• Materials Science

Background:

• Surface-enhanced Raman spectroscopy (SERS) offers high sensitivity and molecular specificity for chemical analysis.
• Current SERS applications are limited by complex sample matrices containing interfering particles and contaminants.
• Existing methods often require extensive sample pre-treatment and purification.

Purpose of the Study:

• To develop a simple, scalable SERS-active substrate combining sample filtration and enhancement.
• To improve the uniformity and stability of SERS-active nanoparticles on a substrate.
• To enable direct SERS detection of analytes in complex real-world samples.

Main Methods:

• Fabrication of SERS-active paper substrates using a spray-deposition technique.
• Incorporation of colloidal nanoparticles with hydroxyethyl cellulose (HEC) polymer before spray-deposition.
• Evaluation of substrate performance using crystal violet as a model analyte and real-world samples (mud, protein mixtures).

Main Results:

• Spray-deposited SERS-paper substrates demonstrated uniform nanoparticle distribution and enhanced stability.
• The HEC polymer protected nanoparticles from oxidation and facilitated their release upon rehydration.
• High sensitivity was achieved, detecting crystal violet down to 4 ng with low signal deviation.
• Effective filtration of micro/macro particles and protein contaminants was observed.
• Successful SERS detection of thiram in mud and melamine in protein mixtures at nanogram levels was demonstrated without pre-treatment.

Conclusions:

• The developed SERS-paper substrate offers a versatile platform for sensitive chemical analysis in complex matrices.
• This integrated filtration and enhancement approach simplifies sample analysis and broadens SERS applicability.
• The technique is scalable and provides a cost-effective solution for on-site and field-based detection.