title: SERS-based quantitative detection of ovarian cancer prognostic factor haptoglobin.
abstract: Surface-enhanced Raman spectroscopy (SERS) is increasingly being used for biosensing because of its high sensitivity and low detection limit, which are made possible by the unique Raman 'fingerprint' spectra from the biomolecules. Here we propose a novel SERS method for the fast, sensitive, and reliable quantitative analysis of haptoglobin (Hp), an acute phase plasma glycoprotein that is widely gaining application as a prognostic ovarian cancer biomarker. We exploited the peroxidase activity of the hemoglobin-haptoglobin (Hb-Hp) complex formed by the selective and specific binding of Hp to free Hb to catalyze the reaction of 3,3',5,5'-tetramethylbenzidine (TMB) substrate and hydrogen peroxide to result in the final product of strongly SERS-active TMB(2+). We observed a linear increase in the SERS signal of TMB(2+) with increasing concentrations of Hb-Hp complex from 50 nM to 34 μM. Based on this concentration-dependent SERS spectrum, we quantified Hp in clinical samples. We observed that our inference about the prognosis of the disease coincided with the histology data and that our method was much more sensitive than the enzyme-linked immunosorbent assay method.
authors.affiliation: Bio-Optical Imaging Group, Singapore Bioimaging Consortium, Agency for Science Technology and Research (ASTAR), Helios, Singapore.
authors.forename: Jayakumar
authors.initials: J
authors.lastname: Perumal
authors.affiliation: Bio-Optical Imaging Group, Singapore Bioimaging Consortium, Agency for Science Technology and Research (ASTAR), Helios, Singapore.
authors.forename: Ghayathri
authors.initials: G
authors.lastname: Balasundaram
authors.affiliation: Departments of Obstetrics and Gynecology and Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: Aniza P
authors.initials: AP
authors.lastname: Mahyuddin
authors.affiliation: Departments of Obstetrics and Gynecology and Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: Mahesh
authors.initials: M
authors.lastname: Choolani
authors.affiliation: Bio-Optical Imaging Group, Singapore Bioimaging Consortium, Agency for Science Technology and Research (ASTAR), Helios, Singapore ; School of Physics, National University Ireland, Galway, Ireland.
authors.forename: Malini
authors.initials: M
authors.lastname: Olivo
mesh_terms: D001560:Benzidines / Q000737:chemistry; D014408:Biomarkers, Tumor / Q000032:analysis*; D005260:Female; D006242:Haptoglobins / Q000032:analysis* / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000378:metabolism*; D010544:Peroxidases / Q000737:chemistry / Q000378:metabolism; D012680:Sensitivity and Specificity; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D001560:Benzidines; D014408:Biomarkers, Tumor; D006242:Haptoglobins; D006454:Hemoglobins; C021758:3,3',5,5'-tetramethylbenzidine; D006861:Hydrogen Peroxide; D010544:Peroxidases
keywords: 3; 3′; 5; 5′-tetramethylbenzidine; SERS-based biosensing; biomarker detection; hemoglobin–haptoglobin complex; ovarian cancer; peroxidase active substrates
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