Long-Term Affinity Modification on Poly(dimethylsiloxane) Substrate and Its Application for ELISA Analysis

Abstract

Poly(dimethylsiloxane) (PDMS) possesses many advantages, such as biocompatibility and high oxygen permeability, which makes it an attractive material for fabricating biodevices. Creating an affinity surface with long-term stability and reactivity for biomolecular interactions on a PDMS substrate, however, is difficult due to its inherent hydrophobicity. In this study, an affinity surface on a PDMS substrate with long-term hydrophilicity and affinity reactivity is reported. This modification is composed of two parts. The bottom part is made of polyelectrolyte multilayers and is capable of providing long-term hydrophilic stability. The top part consists of three protein layers, bovine serum albumin (BSA), anti-BSA, and protein G, and offers an affinity surface for antibody binding and, more importantly, provides favorable orientation and minimum nonspecific binding. The chemical modification for the different stages was monitored by atomic force microscopy (AFM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FT-IR), and contact angle and fluorescence measurements. A long-term PDMS immunodevice (LPID) based on polyelectrolyte multilayers and protein layers was fabricated and applied to the detection of transforming growth factor beta (TGF-beta) protein in mouse serum by the enzyme-linked immunosorbent assay (ELISA) method. Results show that a linear calibration curve was obtained in the concentration range from 500 to 15.125 pg/mL, and the relative standard deviation was less than 3%. Also, the amount of TGF-beta spiked in mouse serum was precisely determined. Results indicate that the modified surface was hydrophilic and reactive to biospecies up to more than 7 days in its dry form. Moreover, the blocking reagent used to reduce nonspecific binding was found to be not necessary for the LPID. Thus, the reported method is expected to hold a great potential for fabricating PDMS-based affinity devices such as protein chips.

Polyelectrolyte multilayers-modified membrane filter for rapid immunoassay: protein condensation by centrifugal permeation

“…19 A number of studies have demonstrated that PEMs exhibit versatile functions with regard to protein adsorption driven by electrostatic forces, hydrogen bonding and hydrophobic interactions, and can contribute to a higher sensitivity of the immunoassay in recent studies. 12,16,[20][21] We investigated the protein adsorption behaviors of ELISA systems, and the relationship between the detection sensitivity and the number of layers of the PDDA/PSS PEMs as compared with conventional polystyrene plates. 12 From the viewpoint of the uniformity of the PEMs surface and the signal to noise ratio, the positive 7-step (PDDA/PSS) 3 PDDA PEMs was an optimized multilayer in the previous study.…”

Polyelectrolyte Multilayers in Microfluidic Systems for Biological Applications

“…Typically, a blocking agent, such as bovine serum albumin (BSA) protein, is used to decrease non-specific binding in enzyme-linked immunosorbent assay (ELISA). Sung et al, 2008, modified the PDMS surface with poly(ethyleneimine) (PEI) and poly(acrylic acid) (PAA) and later cross-linking of the PEMs with amide bonds. The use of this device for detecting low levels of proteins was established by detecting transforming growth factor beta (TGF-β), a cytokine, using ELISA [17].…”

Layer-by-layer functionalized nanotube arrays: A versatile microfluidic platform for biodetection

“…In the latter case, LbL-assembled coatings have been used for the development of microfluidic-based in vitro assays or for studying fundamental cell and tissue biology. For example, Sung et al have modified polydimethylsiloxane surfaces by using LbL coatings to reduce non-specific binding and enhance the detection of low levels of protein 47 . Others have designed a microfluidic platform with LbL coatings for identifying the dengue virus through an enzyme-linked immunosorbent assay (ELISA) approach.…”