title: A Boronate Affinity-Assisted SERS Tag Equipped with a Sandwich System for Detection of Glycated Hemoglobin in the Hemolysate of Human Erythrocytes.
abstract: Phenylboronic acid-functionalized, Ag shell-coated, magnetic, monodisperse polymethacrylate microspheres equipped with a glycoprotein-sensitive sandwich system were proposed as a surface-enhanced Raman scattering (SERS) substrate for quantitative determination of glycated hemoglobin (HbA1c). The magnetization of the SERS tag and the formation of the Ag shell on the magnetic support were achieved using the bifunctional reactivity of newly synthesized polymethacrylate microspheres. The hemolysate of human red blood cells containing both HbA1c and nonglycated hemoglobin was used for determination of HbA1c. The working principle of the proposed SERS tag is based on the immobilization of HbA1c by cyclic boronate ester formation between glycosyl residues of HbA1c and boronic acid groups of magnetic polymethacrylate microspheres and the binding of p-aminothiophenol (PATP)-functionalized Ag nanoparticles (Ag NPs) carrying another boronic acid ligand via cyclic boronate ester formation via unused glycosyl groups of bound HbA1c. Then, in situ formation of a Raman reporter, 4,4'-dimercaptoazobenzene from PATP under 785 nm laser irradiation allowed for the quantification of HbA1c bound onto the magnetic SERS tag, which was proportional to the HbA1c concentration in the hemolysate of human erythrocytes. The sandwich system provided a significant enhancement in the SERS signal intensity due to the plasmon coupling between Ag NPs and Ag shell-coated magnetic microspheres, and low HbA1c concentrations down to 50 ng/mL could be detected. The calibration curve obtained with a high correlation coefficient between the SERS signal intensity and HbA1c level showed the usability of the SERS protocol for the determination of the HbA1c level in any person.
authors.affiliation: Department of Medical Biology and Genetics, Gazi University , 06500, Ankara, Turkey.
authors.forename: Duygu Deniz
authors.initials: DD
authors.lastname: Usta
authors.forename: Kouroush
authors.initials: K
authors.lastname: Salimi
authors.affiliation: Hacettepe University Hospitals Central Laboratory , 06800, Ankara, Turkey.
authors.forename: Asli
authors.initials: A
authors.lastname: Pinar
authors.affiliation: Hacettepe University Hospitals Central Laboratory , 06800, Ankara, Turkey.
authors.forename: İlknur
authors.initials: İ
authors.lastname: Coban
authors.affiliation: Department of Medical Biology and Genetics, Gazi University , 06500, Ankara, Turkey.|Life Sciences Application and Research Center, Gazi University , 06830, Ankara, Turkey.
authors.forename: Turgay
authors.initials: T
authors.lastname: Tekinay
authors.forename: Ali
authors.initials: A
authors.lastname: Tuncel
mesh_terms: D001897:Boronic Acids / Q000737:chemistry*; D004912:Erythrocytes / Q000737:chemistry*; D006442:Glycated Hemoglobin / Q000032:analysis*; D006461:Hemolysis; D006801:Humans; D013059:Spectrum Analysis, Raman
chemical_list: D001897:Boronic Acids; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human; C010686:benzeneboronic acid
keywords: HbA1c; SERS; boronate affinity chromatography; core−shell microspheres; glycoprotein; sandwich assay