A high-strength galactomannan (GA)-based hydrogel with thermal response and pH response is introduced in this paper. GA, N-isopropylacrylamide (NIPAM), N-[3-dimethylamino)propyl]methylacrylamide (DMAPMA), and montmorillonite were used to form hydrogels through a simple mixed static system. Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) were used to characterize the structure and properties of the hydrogels. The compressive strength of the the hydrogel increased from 23.9 to 105.61 kPa with the increase of GA dosage from 0 to 1.5 wt%. When the NIPAM content in the monomer increased from 75% to 95%, the lower critical solution temperature (LCST) of the hydrogel changed from 36.5 to 45.8 °C. When the monomer content was higher than 10wt%, the swelling kinetics of the sample changed from the second-order equation to the first-order equation. With the increase of the proportion of NIPAM monomer, the release rate of bovine serum album in the early stage was faster, and the cumulative release rate was close to 100%.The release rate of bovine serum albumin at 37 °C was higher than that at 25 °C. The release rate of the hydrogel containing bovine serum albumin was the fastest under the condition of pH 7.4, followed by those at pH 6.6 and pH 5.0. The results showed that this thermal-responsive hydrogel has potential applications as a drug carrier for colon delivery.
Keywords: drug carrier; galactomannan; hydrogel; pH-responsive; thermo-responsive.