Surface forces and protein adsorption on dextran- and polyethylene glycol-modified polydimethylsiloxane

Abstract

Dextran and polyethylene glycol (PEG) are often covalently bound to the surface of polydimethylsiloxane (PDMS) for the purpose of modifying its hydrophilicity and biocompatibility. In this work, the effects of the dextran and PEG on the morphology, wetting, and surface charge of the resulting surfaces were quantified and correlated with changes in the amount of fibrinogen and albumin adsorbed from aqueous solution. PDMS films were functionalized in a microwave oxygen plasma to create surface hydroxyl groups that were subsequently aminated by incubation in a (3-aminopropyl)trimethoxysilane (APTES) solution. Oxidized dextran and PEGaldehyde were linked to the surface amines via reductive amination. This process resulted in low surface coverage of immobilized PEG in the end-on conformation and a more uniform and dense distribution of side-on immobilized dextran. The immobilized dextran reduced the contact angle of the PDMS film from 109° to 80° and neutralized the zeta potential over the pH range from 3 to 11. An atomic force microscope was used to measure the interaction force between the modified PDMS and a model hydrophobic surface (polystyrene latex) and a model hydrophilic surface (silica) in both water and electrolyte solutions to show that van der Waals and hydrophobic attractive forces are the dominant forces for protein adsorption in this system. The PEG-and dextran-modified PDMS were exposed to BSA and fibrinogen to test their resistance to protein adsorption. The coatings were ineffective at reducing the adsorption of either molecule, and the dextran-modification of the PDMS caused more BSA to adsorb than in the case of the unmodified PDMS.

Analysis of conditions for the preparation of BSA/MMT composites

“…The d 001 peak is 2.67 nm in the phosphate buffer system. When the KH570 is dissolved in 80% ethanol solution the d 001 peak is scattered, indicating that the existence of water molecules can play an important role in the hydrolysis of KH570.This makes the interaction between MMT surface and KH570 more complicated as more bonds may be produced [11]. The 0.310 nm peak which is the d 005 peak of MMT disappeared after the treatment with KH570.…”

The importance of interfaces in protein drug delivery – why is protein adsorption of interest in pharmaceutical formulations?

“…Examples of modified surfaces that are less prone to protein adsorption are surfaces coated with a thin layer of hydrophilic polymers or modified by PEGylation [179][180][181]. These surface modifications alter the interaction between the surface and the protein by sterically hindering or altering the interaction (Figure 2) [181][182][183].…”

Surface modification of polydimethylsiloxane with a covalent antithrombin–heparin complex to prevent thrombosis

“…Protein adsorption leads to initiation of the coagulation pathways, and to platelet adhesion and activation. [1,2,4,5,[7][8][9] Surface modification is required to prevent these interactions.…”