Carbohydrate Polymers 87 (2012) 1433–1439 Contents lists available at SciVerse ScienceDirect Carbohydrate Polymers jo u rn al hom epa ge: www.elsevier.com/locate/carbpol Interpenetrating biopolymer network based hydrogels for an effective drug delivery system Arti Vashist a , Y.K. Gupta b,1 , Sharif Ahmad a,∗ a Materials Research Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025, India b Department of Pharmacology, All India Institute of Medical Sciences, New Delhi 110029, India a r t i c l e i n f o Article history: Received 4 July 2011 Received in revised form 8 September 2011 Accepted 11 September 2011 Available online 16 September 2011 Keywords: Hydrogels Drug delivery Biopolymers Chitosan Degradation a b s t r a c t Discovery of hydrogels has resulted in developing competent controlled-release drug delivery systems. Present study describes the synthesis and characterization of novel pH responsive hydrogels of chitosan, hydroxyl ethyl cellulose (HEC) and polyol prepared by physical blending of the three components in different ratios. Vegetable oil derived polyol seems to act as a filler and cross linking agent. The synthe- sized hydrogels were characterized using FT-IR spectroscopy, thermo gravimetric analysis (TGA), Optical microscopy and scanning electron microscopy (SEM). Equilibrium swelling behavior of hydrogels in water and different buffers with pH values (2, 4, 7.3, and 8) indicated the sustained expansion of the films in different pH solutions. © 2011 Elsevier Ltd. All rights reserved. 1. Introduction During the last three decades, momentous advances have been made in the controlled release drug delivery of therapeutic agents (Chilin & Metters, 2006; Gurski, Jha, Zhang, Jia, & Farach-Carson, 2009; Kopecek, 2007). The focus is now to design cost effective drug delivery systems and for the nontraditional routes of admin- istration with the competence for self-regulating delivery. Hydrogels have played a vital role in the development of con- trolled release drug delivery systems. Hydrogels are the three dimensional cross linked networks of water soluble polymers. These materials when placed in excess water are able to swell rapidly and retain large volumes of water in their swollen struc- tures. The characteristics features of hydrogels are ability to alter their volumes and properties in response to the external stim- uli such as pH, temperature, ionic strength and electric field. The low interfacial tension with the surrounding biological flu- ids and tissues make hydrogels biocompatible which minimizes the driving force for protein absorption and cell adhesion (Ganji & Vasheghani-Farahani, 2009). The high water content makes them biocompatible. However, high water content has limited their use as a drug carrier to a certain extent; because of dissolution before ∗ Corresponding author. Tel.: +91 11 26827508; fax: +91 11 26840229. E-mail addresses: arti vashist 19@yahoo.com (A. Vashist), yk.ykgupta@gmail.com (Y.K. Gupta), sharifahmad jmi@yahoo.co.in (S. Ahmad). 1 Tel.: +91 11 26593282. the drug can be delivered. To overcome this drawback the hydrogels have been cross linked with various cross linkers or hydrophobic groups to form interpenetrating networks (IPN’s and copolymers). The hydrogels simulate some hydrodynamic properties of natu- ral biological gels, cells, and tissues in many ways (Henriksen, Green, Smart, Smistad, & Karlsen, 1996). Hydrogels can be grafted onto biomaterials by physical adsorption, physical entrapment, graft coupling, and polymerization (El-Tahlawy, El-Rafie, & Aly, 2006; Sadeghi, 2010). The principal market of biomaterials is in the areas of cardiovascular implants, orthopedic implants, intravas- cular, urinary tract catheters, wound dressing, intra ocular lenses, biosensors, and controlled release devices. All of these biomaterials will improve their biocompatibility through coating with hydrogels (Bavaresco, Zavaglia, Malmonge, & Reis, 2002). The semi interpen- etrating polymer network hydrogels of chitosan and poly-(acryl amide) (PAAm) on the other hand are well characterized (Kim, Shin, Kim, & Kim, 2005). It is an interesting material for pervapo- ration membranes or biomedical devices (Kalyani, Biduru, Sridhar, & Krishnaiah, 2006). The utilization of various natural polymers in drug delivery continues to be a subject of great interest. In the present study HEC, non-ionic carbohydrate polymer and another natural, non toxic and biocompatible chitosan obtained by alkaline deacetylation of chitin, which can be completely digested by the colonic bacteria have been used (Tozaki, 1997). These properties make chitosan a good candidate for the development of novel drug delivery systems (Molinaro, Leroux, Demas, & Adam, 2002). Despite the numerous advantages and unique properties of Chitosan, its films are quite brittle, which limits its application in dosage form 0144-8617/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.carbpol.2011.09.030