Potassium salt version of urazole gels were placed into DI water. Then, concentrated HCl is added until pH of solution becomes 1. Gels were kept at this pH for 4 hours and then dialyzed against DI water several times to remove HCl and KCl completely. Synthesis of poly(hexamethylene-semicarbazide): In a typical synthesis, 4.3 mL poly(hexamethylene diisocyanate) was added to semicarbazide solution (3.3 gram) in 100 mL anhydrous tetrahydrofuran (THF) under inert conditions. This mixture was stirred for 10 minutes while keeping flask in an ice bath. Then ice bath is removed, and reaction kept stirred for an hour at Scheme 1: Synthesis of semicarbazide gel (3), urazole potassium salt hydroge (4) and urazole gel as free acid (5). ambient temperature. White polymeric sticky material was precipitated in the reaction flask over time. Then-THF decanted and 100mL fresh THF was added and stirred for 30 minutes to remove excess semicarbazide. Finally, THF was decanted, and material dried under vacuum. Isolate yield: 7.43 gram 93%. Synthesis of poly(hexamethylene-urazole): 2 grams of poly(hexamethylene-semicarbazide) were added into oven dried 100 mL round bottom flask. Then, 1 gram of anhydrous K2CO3 and 60 mL anhydrous ethanol were added. Mixture was refluxed for 24 hours. Then, most of the ethanol was decanted carefully and the rest removed under vacuum. Sticky polymer -K2CO3 mixture dissolved in ice-water mixture. Then, 6M HCl added slowly, and white solid was precipitated immediately. More HCl added until pH of solution became 1-2. Product was collected by vacuum filtration and washed with excess DI water to remove acid. Sticky polymeric material was dissolved in CHCl3 and transferred into vial. Finally, chloroform removed under vacuum. Isolated yield: 1.61 grams. Synthesis of triazolinedione gel: In a typical synthesis, 200 mg of urazole gel placed into 3 mL dichloromethane. Then, 100 µL HNO3 was added, and mixture was shaken vigorously for 3-5 minutes. Finally, gels were filtered and washed with excess dichloromethane to remove residual HNO3. Quantification of Urazole Content: 150 mg of 2-naphthol dissolved in 7.5 mL CDCl3. To this solution, one drop of acetonitrile was added to use as integration reference. 1 mL aliquots of this solution were added onto three batches of the TAD-gel that was oxidized and washed 10 minutes ago. After 45 minutes, 0.7 mL of these solutions were taken for NMR analysis. 2-naphthol loss was determined by NMR integration after normalizing acetonitrile peaks in each spectrum. Determination of swelling ratio of hydrogels: Swollen hydrogels were frozen using liquid nitrogen and then freeze dried to complete dryness. Then, freeze dried gels were placed into DI water or phosphate buffer. Masses of wet hydrogel was recorded until it reaches equilibrium. Finallly, swelling ratio was calculated using the formula below. Swelling ratio = (Mass of wet gel -mass of freeze dried gel)/mass of freeze dried gel x 100 Ion-exchange study: 550mL of tap water was collected into a 1L Erlenmeyer flask. 50 mL of it was separated and kept as a control group. 50 grams of dry urazole-potassium gels were added to the tap water. After 2,8 and 120 hours, 10mL aliquots of water were taken for ion-chromtography analysis. Samples were filtered thorough 0.22um or 0.45um filter before analysis Cell Culture. Human skin fibroblast (HSF) cells (ATCC, PCS-201-030) were incubated at 37 °C under in humidified atmosphere air with 5% CO2 and cultured in Dulbecco's modified Eagle's medium (DMEM, Sigma, Germany) supplemented with 5% Penicillin-Streptomycin Ampicillin (PSA), 5% l-glutamine, and 10% fetal bovine serum (FBS) in tissue culture flasks (TPP, Germany). Cells were harvested Trypsin/D-Hanks solution (0.25 w/v %, Gibco) at reach 90% confluency then seeded at a density of 5 × 10 3 cells/well in a 96-well plate for incubation 24 h. Cell Viability Assay Cell viability analysis was measured using tetrazolium salt WST-1 colorimetric assay after treatment of hydrogel extract on seeded cells in a 96-well plate. Autoclaved samples were prepared 0.02 mg based on ISO 10993-12 protocol and incubated in 1 ml DMEM 72 h at 37 °C at 80 rpm. Therefore, seeded cells were cultivated as 100% and 50% extract concentration and negative and positive controls contained no material and 5% DMSO, respectively. After 2h, 6h, 24h, 48h, and 72h incubation, followed by the removed medium from each well was rinsed with PBS to clean the complete extraction residue. The treated cells were cultivated with a medium contained %10 WST-1 at 3h. Consequently the formazan was converted from tetrazolium salt in living cells, medium was measured absorbance at 450 nm with an ELISA reader. The cell viability percentage data calculated with normalized negative control.