Polydopamine/silver substrates stemmed from chiral silica for SERS differentiation of amino acids enantiomers.

Polydopamine (PDA) and silver (Ag) nanoparticles were firstly generated on chiral silica nanofibers and then detached from silica to form PDA/Ag composites. The as-obtained PDA/Ag showed surface enhanced Raman scattering (SERS) activity but very weak circular dichrosim (CD) optical activity. Interestingly, the PDA/Ag substrates could make a pair of tyrosine (or phenylalanine) enantiomers show different Raman scattering signals intensities, where the differences could reach 3 times. On contrast, PDA/Ag prepared by using racemic or achiral silica did not exhibit such discrimination performance. Therefore, this research offered a novel SERS-based enantiomeric differentiation method with the assistance of plasmonic metals-containing substrates stemmed from intrinsically chiral inorganic silica.