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.

Recent trends in sorbents for bioaffinity chromatography

“…As another strategy commonly employed in the synthesis of boronate affinity sorbents, phenylboronate ligands are immobilized on functionalized support materials via organic linkers. Different supports like core-shell magnetic structures [111][112][113], alginate [114], silica [110,115], zirconia [116], graphene oxide [117], and methacrylate-based polymer [118] with different porous properties have been used in the preparation of boronate affinity sorbents with this strategy. The PBA ligands that have been widely used in post modifica-tion of support materials are APBA and VPBA.…”

“…Then FPBA was covalently attached onto the molecular brushes via their amine groups [117]. Recently, PBA‐functionalized, Ag shell coated, magnetic polymer microspheres carrying a glycoprotein‐sensitive sandwich system were synthesized as a surface‐enhanced Raman scattering (SERS) substrate for quantitative determination of glycated hemoglobin in hemolysate of human erythrocytes up to 50 ng/mL (HbA1c) [118].…”

Recent Advances in Surface-Enhanced Raman Scattering Magnetic Plasmonic Particles for Bioapplications

“…Therefore, magnetic SERS has been applied in disease-based protein detection. Target proteins include human immunoglobulin G [ 20 , 36 ], prostate specific antigen [ 26 , 35 , 93 ], urinary erythropoietin [ 94 ], sepsis-specific biomarkers [ 95 ], carcinoembryonic antigen [ 96 ], thrombin, platelet derived growth factor BB, immunoglobulin E [ 62 ], and glycated hemoglobin [ 97 ]. These MPPs are designed with very specific components, such as antibodies, aptamers or chemical molecules [ 62 , 95 , 97 ].…”

Highly selective magnetic affinity purification of histidine-tagged proteins by Ni2+ carrying monodisperse composite microspheres

“…33,34 The magnetization of poly(MAA-co-EDMA) microspheres was performed as described elsewhere. 35 The magnetic poly(MAA-co-EDMA) microspheres were used as a template for synthesis of monodisperse, magnetic SiO 2 microspheres. Briey, the poly(MAA-co-EDMA) microspheres were dispersed in an aqueous solution containing TBAI, ammonia, 2-propanol and distilled water for 1 hour under mechanical stirring.…”

“…33,34 The magnetization of poly(MAA-co-EDMA) microspheres was carried out by the precipitation of magnetic Fe 3 O 4 nanoparticles into the porous interior of microspheres. 35 The magnetic polymer microspheres were then utilized as a template for the synthesis of monodisperse silica microspheres. The presence of NH 4+ cations in the reaction medium led to the hydrolysis and condensation reaction of TEOS onto the magnetic polymer microspheres.…”