Thermal and kinetic evaluation of biodegradable thermo-sensitive gelatin/poly(ethylene glycol) diamine crosslinked citric acid hydrogels for controlled release of tramadol

[Display omitted] •The properties of PEGD:CA/GEL can be tuned in terms of their application.•The swelling behavior of PEGD:CA/GEL and PEGD:GTA/GEL is temperature-dependent.•The addition of tramadol increases the mechanical properties of hydrogels.•The drug release mechanism for PEGD:CA/GEL follows an anomalous mechanism. Nowadays, hydrogels have become ideal materials for use in biomedical applications by virtue of their biodegradability and biocompatibility. In this study, poly(ethylene glycol) diamine (PEGD) based hydrogels were synthetized using as crosslinking agents citric acid (CA) or glutaraldehyde (GTA), and gelatin (GEL) as hydrogel vehicle. The hydrogels were studied for drug release in vitro using tramadol (TR) as a model drug. Thermal studies under isothermal and non-isothermal conditions were conducted. The elastic module (G′) showed higher values than the loss module (G′) confirming that the contribution of the elastic segments in both materials is more significant than the viscous ones. Aqueous stability, swelling and drug release properties were determined. The swelling analysis indicated that both hydrogels are temperature dependent. The kinetics studies showed an anomalous drug release mechanism. PEGD:CA/GEL hydrogel behave as an elastic matrix strong enough to maintain the drug dosage.