Surface Functionalization and Escherichia coli Detection Using Surface-Enhanced Raman Spectroscopy Driven by Functional Organic Polymer/Gold Nanofilm-Based Microfluidic Chip

• Published in: Biosensors (Basel) Vol. 13; no. 12; p. 994
• Main Authors: Cortes-Cano, Hugo, Olvera, Lilian Iraís, Méndez-Aguilar, Emilia M, España-Sánchez, Beatriz Liliana, Arriaga, Luis Gerardo, Oza, Goldie, Herrera-Celis, José
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 21.11.2023
• Subjects: Antibiotics; Bacteria; Biological activity; Biomonitoring; Biosensors; Contamination; Cysteamine; E coli; Electric fields; Escherichia coli; Escherichia coli - isolation & purification; Fabrication; functional organic polymer; Gold; Gold - chemistry; Infections; Membranes; Metal Nanoparticles - chemistry; Methacrylic acid; Microchannels; microfluidic prototype; Microfluidics; Micromachining; microorganism detection; Microorganisms; Monomers; Nanoclusters; Nanoparticles; Pathogens; Physical characteristics; Polymers; Polymethyl Methacrylate; Polymethylmethacrylate; Prototypes; Raman spectra; Raman spectroscopy; Reagents; Salmonella; Sensors; Spectroscopy; Spectrum Analysis, Raman - methods; surface functionalization; surface-enhanced Raman spectroscopy; Three dimensional models; Voltammetry; X ray photoelectron spectroscopy; Escherichia coli; microfluidic prototype; simulation; surface functionalization; functional organic polymer; power enhancement factor; microorganism detection; surface-enhanced Raman spectroscopy
• ISSN: 2079-6374; 2079-6374
• DOI: 10.3390/bios13120994

In this work, a microfluidic prototype based on polymeric materials was developed to monitor surface processes using surface-enhanced Raman spectroscopy (SERS), keeping the reagents free of environmental contamination. The prototype was fabricated on poly(methyl methacrylic acid) (PMMA). A micrometric membrane of a functional organic polymer (FOP) based on -terphenyl and bromopyruvic acid monomers was formed on the PMMA surface to promote the formation of metal nanoclusters. Au nanosized film was deposited on the FOP membrane to give rise to the SERS effect. A microchannel was formed on another piece of PMMA using micromachining. A representative 3D model of the prototype layer arrangement was built and simulated in COMSOL Multiphysics to approximate the electric field distribution and calculate the power enhancement factor as the Au film changes over time. The fabrication process was characterized using UV-visible and Raman spectroscopies and XPS. The prototype was tested using a Raman microscope and liquid solutions of cysteamine and ( ). The simulation results demonstrated that the morphological characteristics of the Au layer give rise to the SERS effect, and the power enhancement factor reaches values as high as 8.8 × 10 on the FOP surface. The characterization results showed the formation of the FOP and the Au film on PMMA and the surface functionalization with amine groups. The Raman spectra of the prototype showed temporal evolution as different compounds were deposited on the upper wall of the microchannel. Characteristic peaks associated with these compounds were detected with continuous monitoring over time. This prototype offers many benefits for applications like monitoring biological processes. Some advantages include timely surface evaluation while avoiding environmental harm, decreased use of reagents and samples, minimal interference with the process by measuring, and detecting microorganisms in just 1 h, as demonstrated with the sample.