title: Specific chemical effects on surface-enhanced Raman spectroscopy for ultra-sensitive detection of biological molecules.
abstract: Achieving high signal amplification in surface-enhanced Raman scattering (SERS) is important for reaching single molecule level sensitivity and has been the focus of intense research efforts. We introduce a novel chemical enhancer, lithium chloride, that provides an additional order of magnitude increase in SERS relative to previously reported enhancement results. We have duplicated single molecule detection of the DNA base adenine that has previously been reported, thereby providing independent validation of this important result. Building upon this work, we show that the chemical enhancer LiCl produces strong SERS signal under a wide range of experimental conditions, including multiple laser excitation wavelengths and target molecule concentrations, for nucleotides, nucleosides, bases, and dye molecules. This is significant because while selection of anions used in chemical enhancement is well known to affect the degree of amplification attained, cation selection has previously been reported to have no major effect on the magnitude of SERS enhancement. Our findings indicate that cation selection is quite important in ultra-sensitive SERS detection, opening the door to further discussion and theory development involving the role of cations in SERS.
authors.affiliation: Intel Research, Intel Corporation, 2200 Mission College Blvd, SC2-24, Santa Clara, California 95054, USA.
authors.forename: Tae-Woong
authors.initials: TW
authors.lastname: Koo
authors.forename: Selena
authors.initials: S
authors.lastname: Chan
authors.forename: Lei
authors.initials: L
authors.lastname: Sun
authors.forename: Xing
authors.initials: X
authors.lastname: Su
authors.forename: Jingwu
authors.initials: J
authors.lastname: Zhang
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Berlin
mesh_terms: D000225:Adenine / Q000032:analysis* / Q000737:chemistry*; D001704:Biopolymers / Q000032:analysis* / Q000737:chemistry*; D018021:Lithium Chloride / Q000737:chemistry*; D008832:Microchemistry / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012996:Solutions
chemical_list: D001704:Biopolymers; D012996:Solutions; D018021:Lithium Chloride; D000225:Adenine