Temperature/pH-Sensitive Double Cross-Linked Hydrogels as Platform for Controlled Delivery of Metoclopramide

Abstract

Novel double cross-linked (DC) hydrogels with pH-/temperature-sensitive properties were designed and developed. Therefore, linear pH-sensitive poly(methyl vinyl ether-alt-maleic acid) (P(VME/MA)) macromolecules were absorbed within a thermosensitive poly(N-isopropylacrylamide-co-hydroxyethylacrylamide)-hydrogel (PNH) and, subsequently, cross-linked together through a solvent-free thermal method. As a novelty, double cross-linked hydrogels were obtained from previously purified polymers in the absence of any solvent or cross-linking agent, which are generally harmful for the body. The new DC structures were characterized by FT–IR spectroscopy, SEM, swelling kinetic measurements, and mechanical tests. The resulting scaffolds exhibited interconnected pores and a flexible pattern, compared to the brittle structure of conventional PNH. The swelling kinetics of DC hydrogels were deeply affected by temperature (25 and 37 °C) and pH (7.4 and 1.2). Furthermore, the hydrogels absorbed a great amount of water in a basic environment and displayed improved mechanical properties. Metoclopramide (Met) was loaded within DC hydrogels as a model drug to investigate the ability of the support to control the drug release rate. The results obtained recommended them as convenient platforms for the oral administration of drugs, with the release of the largest part of the active principle occurring in the colon.

Electrochemical Wearable Biosensors and Bioelectronic Devices Based on Hydrogels: Mechanical Properties and Electrochemical Behavior

“…Highly cross-linked hydrogels tend to be less hydrophilic than loosely cross-linked hydrogels due to reduced water accessibility to polymer chains [ 154 ]. Additionally, the type of cross-linker and pH of the environment can influence the hydrophilicity of hydrogels [ 155 ]. The properties of HWEBs can be tuned to optimize their performance, and the selection of hydrophilic/hydrophobic properties of hydrogels must be carefully balanced with the mechanical requirements of HWEBs.…”

Physicochemical Properties of Temperature-/pH-Sensitive Hydrogel Materials

“…Hydrogels, owing to their distinctive physical and chemical properties, have found extensive applications across diverse industrial domains. The hydrogel properties of materials depend on the degree and nature of cross-linking and the degree of crystallinity of the polymer [1,2]. Notably, hydrogels exhibit a pronounced potential for biomedical applications, such as tissue engineering and drug delivery, which is attributable to their hydrophilicity, superabsorbent capacity, biodegradability, and biocompatibility.…”