Polyphenol-assisted assembly of Au-deposited polylactic acid microneedles for SERS sensing and antibacterial photodynamic therapy.

3D SERS microneedles with self-assembled AuNPs were fabricated with tannic acid (chemical glue and reductant) on polylactic acid microneedles for in-depth chemical and biomolecular analysis, with LOD values below 200 ppb for small molecules and 10 2 CFU cm -2 for bacteria. The MB/Au-microneedles were used for photodynamic therapy with SERS-monitored photosensitizer degradation.