Laser transparent multiplexed SERS microneedles for in situ and real-time detection of inflammation

It is a significant challenge to perform painless invasive detection of inflammation progression in relation to the evolution of pH, redox potential , and reactive oxygen species (ROS) levels in an in situ and real-time manner. In this work, polydopamine-modified, silver nanoparticle-decorated poly (methyl methacrylate) microneedles ( [email protected] @MNs) have been developed as a multiplexed surface enhanced Raman scattering (SERS) diagnostic platform. Using rhodamine 6G as the Raman signal molecule, the [email protected] @MNs demonstrated a significant enhancement with reasonable linearity in the range of 10 −3 -10 −9  mol/L and the limit of detection is 1.0 × 10 −10  mol/L 4-mercaptobenzoic acid, anthraquinone-2-carboxylic acid and para-aminothiophenol were covalently anchored on [email protected] @MNs SERS substrate. I 1143 /I 1183 , I 1606 /I 1667 and I 1143 /I 1077 were used as assay standards for pH, redox potential and ROS level detection, respectively. The SERS multiplexed transparent microneedles (SERS mtMNs) linearly responded to pH in the range of 4.0–8.0, redox potential in the range of 417.0–599.8 mV, and ROS levels in the range of 0–480 ng/mL, demonstrating a significant ability to detect complex inflammation in vivo , in situ and in real-time.