title: Plasmon-tuned silver colloids for SERRS analysis of methemoglobin with preserved nativity.
abstract: Optically tuned silver nanoparticles (AgNP's) functionalized with ω-mercaptoalkanoic acids are synthesized and used as a signal amplifier for the surface-enhanced resonance Raman scattering (SERRS) study of heme cofactor in methemoglobin (metHb). Even though both mercaptopropionic acid (MPA)- and mercaptononanoic acid (MNA)-functionalized AgNP's exemplify vastly enhanced SERRS signal of metHb, MNA-AgNP's amplify the SERRS signal amid preservation of the nativity of the heme pocket, unlike MPA-AgNP's. The electrostatic interaction between MNA-AgNP's and metHb leads to instant signal enhancement with a Raman enhancement factor (EF(SERS)) of 4.2 × 10(3). Additionally, a Langmuir adsorption isotherm has been employed for the adsorption of metHb on the MNA-AgNP surface, which provides the real surface coverage and equilibrium constant (K) of metHb as 139 nM and 3.6 × 10(8) M(-1), respectively. The lowest detection limit of 10 nM for metHb has been demonstrated using MNA-AgNP's besides retaining the nativity of the heme pocket.
authors.affiliation: Department of Chemistry, Vivekananda College, Tiruvedagam West, Madurai-625 214, Tamilnadu, India.
authors.forename: Govindasamy
authors.initials: G
authors.lastname: Kalaivani
authors.forename: Arumugam
authors.initials: A
authors.lastname: Sivanesan
authors.forename: Ayyadurai
authors.initials: A
authors.lastname: Kannan
authors.forename: N S
authors.initials: NS
authors.lastname: Venkata Narayanan
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Kaminska
authors.forename: Ranganathan
authors.initials: R
authors.lastname: Sevvel
mesh_terms: D002264:Carboxylic Acids / Q000737:chemistry; D003102:Colloids; D053768:Metal Nanoparticles / Q000737:chemistry; D008706:Methemoglobin / Q000737:chemistry*; D008958:Models, Molecular; D055620:Optical Phenomena; D011487:Protein Conformation; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D020349:Surface Plasmon Resonance; D013499:Surface Properties
chemical_list: D002264:Carboxylic Acids; D003102:Colloids; D012834:Silver; D008706:Methemoglobin