title: Biofabrication of chitosan-silver composite SERS substrates enabling quantification of adenine by a spectroscopic shift.
abstract: Surface-enhanced Raman scattering (SERS) has grown dramatically as an analytical tool for the sensitive and selective detection of molecules adsorbed on nano-roughened noble metal structures. Quantification with SERS based on signal intensity remains challenging due to the complicated fabrication process to obtain well-dispersed nanoparticles and well-ordered substrates. We report a new biofabrication strategy of SERS substrates that enable quantification through a newly discovered spectroscopic shift resulting from the chitosan-analyte interactions in solution. We demonstrate this phenomenon by the quantification of adenine, which is an essential part of the nucleic acid structure and a key component in pathways which generate signal molecules for bacterial communications. The SERS substrates were fabricated simply by sequential electrodeposition of chitosan on patterned gold electrodes and electroplating of a silver nitrate solution through the chitosan scaffold to form a chitosan-silver nanoparticle composite. Active SERS signals of adenine solutions were obtained in real time from the chitosan-silver composite substrates with a significant concentration-dependent spectroscopic shift. The Lorentzian curve fitting of the dominant peaks suggests the presence of two separate peaks with a concentration-dependent area percentage of the separated peaks. The chitosan-mediated composite SERS substrates can be easily biofabricated on predefined electrodes within microfluidic channels for real-time detection in microsystems.
authors: Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, MD 20742, USA.
authors: X L
authors: XL
authors: Luo
authors: S
authors: S
authors: Buckhout-White
authors: W E
authors: WE
authors: Bentley
authors: G W
authors: GW
authors: Rubloff
mesh_terms: D000225:Adenine / Q000032:analysis*; D048271:Chitosan / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry / Q000648:ultrastructure; D012825:Silicon / Q000737:chemistry; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman
chemical_list: D012834:Silver; D006046:Gold; D048271:Chitosan; D000225:Adenine; D012825:Silicon