High-sensitivity measurement of immunoglobulin G (IgG) using HRP-IgG-phospholipid polymer conjugate

This report describes the high-sensitivity measurements of immunoglobulin (IgG) with the help of a phospholipid polymer conjugate, 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer-IgG-horseradish peroxidase (HRP) conjugate. The phospholipid polymer, poly(MPC-co-2-aminoethyl methacrylate) (PMAE), was synthesized. To prepare the 1-step conjugate, IgG and PMAE were chemically modified with HRP at the same time. To prepare the 2-step conjugate, PMAE was first chemically modified with HRP, and then IgG was chemically modified. The activities of 1-step and 2-step conjugates significantly decreased compared with that of a conventional IgG conjugated with HRP (conventional conjugate) (p 0.05). The detection sensitivity of the 1-step and 2-step conjugates was also compared with that of conventional conjugate. When 0.5 µg/mL anti(goat IgG)IgG was used as an analyte, compared with a conventional conjugate, the values of Δ absorbance of the 1-step and 2-step conjugates were 4.8 and 9.8 times respectively. These results demonstrate that high-sensitivity measurements are possible using HRP-IgG-PMAE conjugate.