Microfluidic paper strips for SERS analysis
- Surface enhanced Raman scattering (SERS) is a fast and sensitive spectroscopic method for the identification of analytes. With available portable Raman spectrometers, on-site analysis is possible. However, for on-site analysis, SERS substrates, which are cheap, easy to prepare, and simple in sample handling are necessary. Relevant analytes in the addressable concentration region for SERS are e.g. antibiotics and pesticides. Here, we present paper-based test strips for SERS analysis which are coated with silver nanoparticles. The coating was realized with different deposition methods of nanoparticle solutions. The papers were also functionalised with hydrophobic barriers to create μPADs. The strips were tested with selected analytes (e.g., adenine, rhodamine-6G) over a broad concentration range. The focus of our study lay on reproducibility and optimum SERS signal intensity.
For the quantification of analytes, highly reproducible signal intensities are necessary. We have realized thisSurface enhanced Raman scattering (SERS) is a fast and sensitive spectroscopic method for the identification of analytes. With available portable Raman spectrometers, on-site analysis is possible. However, for on-site analysis, SERS substrates, which are cheap, easy to prepare, and simple in sample handling are necessary. Relevant analytes in the addressable concentration region for SERS are e.g. antibiotics and pesticides. Here, we present paper-based test strips for SERS analysis which are coated with silver nanoparticles. The coating was realized with different deposition methods of nanoparticle solutions. The papers were also functionalised with hydrophobic barriers to create μPADs. The strips were tested with selected analytes (e.g., adenine, rhodamine-6G) over a broad concentration range. The focus of our study lay on reproducibility and optimum SERS signal intensity.
For the quantification of analytes, highly reproducible signal intensities are necessary. We have realized this reproducibility in acceptable quality. Moreover, employing intensity vs concentration calibration for the analytes, data analysis revealed a behaviour that was best described by a Langmuir isotherm, stressing the strong distance dependence of the SERS effect. For a fast and reproducible analysis of the data, a Labview program was finally compiled, which was fed with the calibration data and derived the concentration of analyte unknowns accordingly.…