Application of biodegradable superabsorbent hydrogel composite based on Gum ghatti-co-poly(acrylic acid-aniline) for controlled drug delivery Kashma Sharma a , Vijay Kumar a, * , Babulal Chaudhary b , B.S. Kaith c , Susheel Kalia d , H.C. Swart a, ** a Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein, ZA9300, South Africa b Science and Engineering Research Board, Department of Science and Technology, New Delhi,110016, India c Department of Chemistry, Dr. B.R. Ambedkar National Institute of Technology, Jalandhar, Punjab,144011, India d Department of Chemistry, Army Cadet College Wing, Indian Military Academy, Dehradun, 248007, UK, India article info Article history: Received 4 November 2015 Received in revised form 6 December 2015 Accepted 21 December 2015 Available online 24 December 2015 Keywords: Cross-linked hydrogels ToF-SIMS Biodegradation Drug delivery abstract In this work, biodegradable hydrogel composite gum ghatti-co-poly(acrylic acid-aniline) (Gg-co-pol- y(AA-ANI) was prepared through graft copolymerization of ANI onto Gg-co-poly(AA) chains, in the presence of N,N’-methylene-bis-acrylamide (MBA) and ammonium persulphate (APS) as a crosslinker- initiator system in an aqueous solution. The matrix Gg-co-poly(AA) was synthesized by polymerizing AA onto Gg backbone using MBA and APS as a crosslinker-initiator system. The characterization of the crosslinked hydrogels has been carried out by Time of flight secondary ion mass spectroscopy, Fourier transform infrared, X-ray diffraction and thermogravimetric analysis. These spectroscopic studies confirmed the successful graft polymerization. The biodegradation of the crosslinked hydrogels was analysed using the composting soil method for two months. The initial and final weight of the cross- linked hydrogels were compared as well as the percentage degradation was calculated. The capability of the synthesized hydrogels to be employed as a colon-specific drug delivery vehicle was executed at various pH media using amoxicillin trihydrate as a model drug. The crosslinked hydrogel with the maximum percentage swelling was observed to show best drug absorption. Preliminary kinetic studied were conducted to get an estimated view of the release mechanism. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction In recent decades, escalating interest has been devoted to the development of stimuli-responsive hydrogels owing to their sense to significantly alter their volume and other parameters in acknowledgement to a small change in external and internal mo- tives such as temperature, pressure, pH, and particular chemical, etc. [1e8]. These materials are hydrophilic in nature due to the existence of reactive clusters such aseOH, eCOOH, eNH 2 , eCONH 2 , eSO 3 H which allows them to absorb or retains large quantities of water as well as to contain bioactive materials within their network [9,10]. The advent of advanced drug delivery devices requires cross- linked hydrogels that are non-toxic, biodegradable and renewable in nature with high water absorbency [10e14]. These properties of natural polysaccharides-based hydrogels enable them to be used in the various pharmaceutical field as carriers for drugs, tissue engi- neering, wound dressing, waste water treatment and so on [15e25]. Graft copolymerization of natural polysaccharides resul- ted in the further tuning of their physical and chemical properties that make them smart materials [26,27]. Among the hydrogels used for these applications, cross-linked hydrogels based on poly- saccharide gums and conducting polymers with better water ab- sorbency can play a fundamental role in producing high-quality end products. In this direction natural polysaccharides/polyaniline based graft-copolymers have demonstrated their potential to be efficiently used for various biomedical applications [28e31]. In the previous works, we have reported the free radical poly- merization of different vinyl monomers and aniline onto gum ghatti (Gg) under dissimilar reaction conditions [9,32e34]. * Corresponding author. ** Corresponding author. E-mail addresses: vijays_phy@rediffmail.com, vj.physics@gmail.com (V. Kumar), swarthc@ufs.ac.za (H.C. Swart). Contents lists available at ScienceDirect Polymer Degradation and Stability journal homepage: www.elsevier.com/locate/polydegstab http://dx.doi.org/10.1016/j.polymdegradstab.2015.12.021 0141-3910/© 2015 Elsevier Ltd. All rights reserved. Polymer Degradation and Stability 124 (2016) 101e111