Nanostars-decorated microfluidic sensors for surface enhanced Raman scattering targeting of biomolecules

Novel localised surface plasmon resonance-based sensors exploitable as diagnostic devices through surface enhanced Raman scattering (SERS) represent a powerful solution for the analysis of liquid samples. In this work, we developed a rapid, versatile, low-cost and time-saving strategy combining advanced (3D-printing) and traditional manufacturing (replica molding) processes to prototype polymeric microfluidic devices, integrating all the components into a single portable platform. Microfluidics provide multiplexed capability, adequate miniaturization and robustness, handling simplicity, reliability, as well as low sample and reagents consumption, while the use of polydimethylsiloxane as supporting substrate drastically reduces the final cost. To introduce SERS capability, plasmonic features were incorporated functionalizing substrates with gold nanoparticles (NPs), engineered in terms of shape, size and surface chemistry to play with plasmonic properties as well as to guarantee reproducibility to the NPs immobilization step and consequently to the SERS effect for signal enhancing. To assess the feasibility of the measurements for molecules optical targeting, SERS-microfluidic systems were synergically coupled with a portable fiber-based set-up and Raman spectra of rhodamine 6 G at different concentrations were acquired. To further demonstrate the potentiality of developed SERS-based substrates as point-of-care devices, Raman analysis were successfully implemented on aqueous solutions of amyloid-beta 1-42 (A beta), considered the main biomarkers for Alzheimer's disease.