Surface Modification of Polystyrene Using Polyaniline Nanostructures for Biomolecule Adhesion in Radioimmunoassays

Abstract

The selection of an appropriate surface as a solid phase for coupling antibodies is a critical step in the development of solid-phase immunoassays. Availability of a new method of preactivating the surface of polystyrene tubes with a layer of another polymer for enhanced immobilization of antibodies seems to be promising. In this paper, we report the activation of a polystyrene surface using a layer of polyaniline and its effect on immobilizing antibodies for use as a solid phase in a T3 immunoassay. The modified surface on the polystyrene was characterized by optical absorption, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The modified tubes were coated with antibody and evaluated for their performance in the assay and validated for radioimmunoassay of T3. AFM images of the modified surface showed an enhancement in the surface roughness (Ra of 20.2 nm), as compared to an unmodified surface (Ra of 6 nm), allowing more adsorption of antibodies to the surface. XPS revealed the presence of N (binding energy approximately 400 eV) on the modified surface, which could help the antibody molecules to bind to these preactivated (modified) tubes. The modified tubes, when coated with antibody, not only showed an increase in the binding with the radioiodinated tracer but also improved the precision of coating the antibody. The present method of activating polystyrene surfaces is simple, does not involve severe chemical treatment, and may have wide applicability to functionalize other supports for immobilizing biomolecules.

Fabrication, characterisation and performance of hydrophilic and super-hydrophilic silica as cell culture surfaces

“…Fabrication of silica surfaces on polystyrene Untreated tissue culture polystyrene (PS) Petri dishes (Sarstedt) were coated with a polyaniline (PANI) film; 0.25 M aniline hydrochloride (Sigma) in 1 M HCl in the presence of 0.08 M ammonium persulfate (Sigma-Aldrich) in ddH 2 O in a 1 : 1 molar ratio using a method adapted from Karir et al 29 The PANI coated PS surfaces were treated with 2% v/v glutaric dialdehyde (Sigma-Aldrich) in ddH 2 O at 57 C for 2 h, before further treatment with a 1 mg mL À1 lysozyme (Fluka) in 0.1 M phosphate buffer (pH 7.2) solution for 24 h before aspiration of the excess reagents and stored at 4 C. The surfaces (hydrophilic or super-hydrophilic) were prepared as follows. For the hydrophilic surface, the protein coated surfaces were treated with 1.0 M tetramethoxysilane (TMOS) (Aldrich) in ddH 2 O (pre-hydrolysed with 1.0 mM HCl for 15 min) for 1 hour with 5% glycerol as a drying control agent and then left to dry under ambient conditions.…”

Recent advances in polyaniline based biosensors

“…This piezoelectric biosensor developed for detection of IgG is capable of differentiating the target analyte concentrations between 500 ng mL −1 and 25 g mL −1 with nonspecific binding of ∼10%. Karir et al (2006) have employed a new method of preactivating the surface of polystyrene (PS) tubes with a layer of PANI and reveal its effect on immobilizing antibodies for use as a solid phase in a T 3 immunoassay. AFM analysis shows enhanced roughness in the case of PANI modified surface as compare to unmodified one, allowing more adsorption of antibodies to the surface.…”

Simple fabrication of functionalized surface with polyethylene glycol microstructure and glycidyl methacrylate moiety for the selective immobilization of proteins and cells

“…However, selective immobilization of biomolecules ("patterning") is difficult to achieve because of nonspecific binding of biomolecules onto fabricated microdevices and the limitation of biomolecules' stability for long-term study. Therefore, the fabrication of a unique surface having the capability of prevention of the non-specific binding and high binding performance of biomolecules is the most important tool in various fields [4,5].…”