Smart pH-Sensitive Hydrogel Based on the Pineapple Peel-Oxidized Hydroxyethyl Cellulose and the Hericium erinaceus Residue Carboxymethyl Chitosan for Use in Drug Delivery

Pineapple and hericium erinaceus (HE) produce a lot of residues in the process of food processing. These processed residues are good potential derivative precursors. In this investigation, a simple and non-toxic method was developed to prepare one new composite hydrogel by the Schiff base reaction between the aldehyde group of oxidized hydroxyethyl cellulose (OHEC) from processed pineapple peel residue and the amino group of carboxymethyl chitosan (CMCS) from processed HE residue. Subsequently, a series of experiments toward these new hydrogel polymers including structure characterization and performances were applied. The resultant hydrogel polymers were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy and confirmed with thermogravimetry. It was observed that the modification of cellulose and chitin was adequate, and the synthesis of OHEC/CMCS hydrogel polymers was successful. The gelation time experiments indicated that the shortest gel time was 33 s at a mass ratio of 4:6 (OHEC-70:CMCS). The hydrogel showed good swelling properties. The maximum swelling rate reached 11.58 g/g, and the swelling rate decreased with the increase of the oxidation degree of OHEC. The drug delivery applications of the prepared hydrogel were evaluated with bovine serum albumin (BSA) as a model drug releasing in vitro. It was discovered that the BSA release from the hydrogel was pH sensitive under simulated gastrointestinal conditions. All of these attributes indicate that the novel prepared hydrogel polymers have the potential as good carriers for oral delivery of protein-type drugs.