Poly(glycidyl methacrylate) nanoparticle-coated capillary with oriented antibody immobilization for immunoaffinity in-tube solid phase microextraction: Preparation and characterization

- The nanoparticles were coated onto the inner surface of capillary to provide higher analytical efficiency.
- The antibodies were immobilized on the NP-coated capillary with oriented antibody immobilization.
- The immunoaffinity in-tube SPME/PETIA based on OAI capillary provided 500 times higher sensitivity than PETIA.

A combination between modification with nanoparticles (NP) and oriented antibody immobilization (OAI) on the inner face of capillary was for the first time developed for immunoaffinity in-tube solid-phase microextraction (SPME) to promise high antigen extraction capacity. β2-microglobin (β2MG) and cystatin C (Cys-C) were selected as model antigens. Poly(glycidyl methacrylate) (PGMA) NPs were chemically immobilized onto the capillary by a ring-opening reaction. Antibodies for β2MG and Cys-C were immobilized on the NPs through OAI. Scanning electron micrograph of the OAI capillary clearly showed that the PGMA NPs were coated onto the inner surface of capillary in a dense monolayer. In addition, random antibody immobilized (RAI) capillaries and OAI capillaries without NP were also prepared as controls. The extraction capacities of OAI capillaries were 2.02 and 2.18 mg m−1 for β2MG and Cys-C, and were about 5 and 6 times as many as RAI capillaries and OAI capillaries without NP, respectively. The resultant capillaries were used as in-tube SPME materials to enrich β2MG and Cys-C for particle-enhanced turbidimetric immunoassay. When using 1.0 mg L−1 standard solutions, the recoveries of OAI capillaries, RAI capillaries and OAI capillaries without NP were 103.6% and 96.8%, 48.5% and 31.5%, and 24.2% and 25.7% for β2MG and Cys-C, respectively. Furthermore, the method quantitation limit by OAI capillaries was 5 and 10 times lower than that by RAI capillaries and OAI capillaries without NP, respectively. This result indicated that the NP-coated capillaries with OAI are more suitable for using as immunoaffinity in-tube SPME materials than that with RAI.