Surface enhanced Raman spectroscopy of biomolecules in buffer solution

Controlled creation of SERS-active hot spots in liquid is a challenge in which optical forces can play an important role by promoting the aggregation of metal nanoparticles by optical trapping or by exploiting the radiation pressure. Here we show that laser induced aggregation of gold nanorods in a buffered solution of Bovine Serum Albumin (BSA) leads to the formation of SERS-active agglomerates capable to enhance the Raman scattering of BSA by 5 orders of magnitude, thus allowing the detection of BSA at concentrations as low as 10⁻⁶ M. This occurrence involves optical, mechanical and thermal effects