Controlled release of heparin from polypyrrole‐poly(vinyl alcohol) assembly by electrical stimulation

Abstract

A surface modification technique was developed for the covalent immobilization of poly(vinyl alcohol) (PVA)-heparin hydrogel onto electrically conductive polypyrrole (PPY) film with the objective of achieving controlled release of heparin. First, aldehyde groups were introduced onto PPY film through poly(ethylene glycol) monomethacrylate graft copolymerization and subsequent oxidation in acetic anhydride and dimethyl sulfoxide mixture. Then, the prepared PVA-heparin hydrogel was cast onto the PPY film and covalently immobilized to the film through the reaction between the aldehyde groups on the PPY film and the hydroxyl groups of PVA. X-ray photoelectron spectroscopy was used to characterize the surface-modified film after each stage. The strong attachment of the PVA-heparin layer on the PPY film was confirmed by peel test and scanning electron microscopy. The release behavior of heparin from the substrate with and without electrical stimulation was studied and the experimental results showed that the heparin release rate from the prepared substrate using an electric current of 3.5 mA is twofold higher than that without current.

Applications of conducting polymers and their issues in biomedical engineering

“…Controlled drug release can also be facilitated using a change in CP redox state to increase permeation of drugs such as dexamethasone (Stassen et al 1995;Pernaut & Reynolds 2000). Electrical stimulation of CPs has been used to release a number of therapeutic proteins and drugs like nerve growth factor (NGF; Hodgson et al 1996), dexamethasone (Abidian et al 2006;Wadhwa et al 2006) and heparin (Li et al 2005a). An accelerated release of heparin from the HG immobilized onto PPy films was reported when PPy was electrically stimulated (Li et al 2005a).…”

Neuroactive conducting scaffolds: nerve growth factor conjugation on active ester-functionalized polypyrrole

“…However, the lack offunctional groups on PPy has limited the ability to tailor PPy with various biochemical properties (Lee et al 2006;Song et al 2006;Guimard et al 2007). A number of non-covalent modification techniques have been studied, which involve doping and entrapping different molecules, such as hyaluronic acid (Collier et al 2000), heparin (Li et al 2005), laminin fragments (Cui et al 2003;Stauffer & Cui 2006) and nerve growth factor (NGF; Hodgson et al 1996;Kim et al 2007) during PPy polymerization. Also, affinity peptides that have specific binding to chloride-doped PPy were used to tether RGD peptides and to promote PC12 adhesion (Sanghvi et al 2005).…”

Biodegradable Heparin‐Loaded Microspheres: Carrier Molecular Composition and Microsphere Structure

“…Another strategy is to encapsulate heparin in biodegradable microspheres so that a constant release rate can be sustained for a long period and can be easily adjusted by modifying the encapsulation content and microsphere properties. [11][12][13][14][15][16][17] In this process, release of the anticoagulation drug lowers the probability of thrombosis, but the microsphere carrier material can counteract this effect and lead to thrombosis. To find materials with non-thrombosis or low-thrombosis-causing properties as carriers of anticoagulation drugs is very important in anticoagulation drug delivery.…”