Asian Journal of Pharmaceutics • Jul-Sep 2020 • 14 (3) | 351 Effects of Cross-linker Variation on Swelling Behavior of Hydrogels Farheen Rahman 1 , M. Z. A. Rafiquee 1 , Elham S. Aazam 2 , S. M. Shakeel Iqubal 3 , Aejaz A. Khan 3 , Tasneem Mohammed 3 , Muazzam Sheriff Maqbul 4 , Areej Dawoud 3 , Kayamkani Abedulla Khan 5 , Abdul Rahman Ikbal 3 1 Department of Applied Chemistry, Z.H. College of Engineering and Technology, Aligarh Muslim University, Aligarh, Uttar Pradesh, India, 2 Department of Chemistry, King Abdul Aziz University, Jeddah, Kingdom of Saudi Arabia, 3 Department of General Science, Ibn Sina National College of Medical Sciences, Jeddah 21418, Kingdom of Saudi Arabia, 4 Faculty of Microbiology and Immunology, Ibn Sina National College of Medical Sciences, Al Mahjar Street: 31906, Jeddah 21418, Kingdom of Saudi Arabia, 5 Department of Clinical Pharmacy and Pharmacology, Ibn Sina National College for Medical Studies, Jeddah, Kingdom of Saudi Arabia Abstract Introduction: The main objective of this study is to find the effects of cross-linker variation on swelling behavior of hydrogels at different temperatures, that is, 30 min–120 min. Hydrogels are three-dimensional cross-linked structural arrangement of the polymeric materials with the ability to absorb huge amounts of water while maintaining their dimensional stability. Materials and Methods: A solution of 20% glutaraldehyde (GA) was prepared in 100 ml standard flask by dissolving 20.0 g GA in a standard flask (of capacity 100 ml) and make up the volume up to the mark using demineralized water (DMW). The gelatin-polyethylene glycol (PEG) composite hydrogels were prepared by simultaneous method, in which all the constituent component networks are polymerized concurrently. Different combinations of gelatin-PEG composite hydrogels were prepared with methylene blue (MB) dye in it. Swelling was studied with the help of the following equation: d s s d W -W I= ×100 W Results and Discussion: The observation showed that the decrease in the absorbance of MB release through the sample membrane may be due to the contraction of the microvoids formed between the polymeric chains. Conclusion: Based on our results which conclude that with increasing crosslinking agent from 5 ml to 15 ml, swelling ratio of the prepared sample decreased from 473.83 to 428.97 in DMW due to the decrease in the pore diameter of the sample. As a result, more and more solvent diffuses into the matrix and produce gel with increased swelling ratio. Key words: Cross-linkers, dye, gelatin, glutaraldehyde, hydrogels, polyethylene glycol, spectrophotometer, swelling Address for correspondence: Dr. S. M. Shakeel Iqubal, Department of General Science, Ibn Sina National College for Medical Studies, Jeddah, Saudi Arabia. E-mail: shakeeliqubal@gmail.com Received: 13-05-2020 Revised: 07-06-2020 Accepted: 13-06-2020 INTRODUCTION H ydrogels are three-dimensional cross- linked structural arrangement of the polymeric materials with the ability to absorb huge amounts of water while maintaining their dimensional stability. [1] Hydrogels on the basis of origins can be classified as natural or synthetic. [2] Hydrogel-forming natural polymers are proteins (collagen and gelatin) and polysaccharides (alginate and agarose). These hydrogels have low toxicity and good biocompatibility. [3] The synthetic polymers that form hydrogels are usually obtained through chemical polymerization methods by crosslinking the materials of desirable properties. [4] These hydrogels may have lower interfacial tension, soft and tissue like physical characters, greater permeability to undersized molecules, and release of entrapped molecules in a controlled manner. [4] These properties have made hydrogels a focus of exploration in different biomedical fields, for example, include wound dressings, super absorbents, drug delivery systems, and tissue engineering. [1] Many of the hydrogels are responsive to fluctuations in physical and chemical stimuli such as ORIGINAL ARTICLE