LAUSR

Abstract A bioinspired nanoflower structure was fabricated on microneedle (MN) to utilize as a surface-enhanced Raman scattering (SERS) sensor for intradermal sensing applications. On the surface of poly (lactic-co-glycolic acid) (PLGA) MN, polydopamine (PD) was coated as an interlayer, and the hydroxyapatite (HA) which is a flower-like-structured bone mineral was crystalized via a bio-mineralization in simulated body fluid (SBF). Au was deposited on the HA-coated microneedle (HA-MN) to generate SERS effect. Scanning electron microscopy (SEM) images showed the nanoflower structures of Au-coated HA-MN (Au-nanoflower on microneedle; NFMN) and dense Au nanoislands (AuILs) formed on each lath-like petal surface. After SERS characterization of the NFMN-SERS sensor, electromagnetic field distribution was investigated by finite-difference time-domain (FDTD) simulation to identify origin of the SERS effect. On the NFMN-SERS sensor, methylene blue (MB) was detected down to a concentration of 50 nM with uniform tip-to-tip signal intensity. Furthermore, the feasibility of the NFMN-SERS sensor for intradermal sensing was investigated using a skin phantom model. The MB molecule contained in the dermis region was detected down to 1 nM after simple insertion and withdrawal. The developed NFMN-SERS sensor is expected to be applied for various intradermal sensing, especially for chemical biomarkers in interstitial fluids of skin.