POSS Hybrid Robust Biomass IPN Hydrogels with Temperature Responsiveness

Abstract

In order to improve the performance of traditional sodium alginate (SA) hydrogels cross-linked by Ca2+ ions to meet greater application demand, a strategy was designed to structure novel SA-based gels (named OP-PN gels) to achieve both stimulus responsiveness and improved mechanical strength. In this strategy, the SA chains are co-cross-linked by CaCl2 and cationic octa-ammonium polyhedral oligomeric silsesquioxane (Oa-POSS) particles as the first network, and an organically cross-linked poly(N-isopropyl acrylamide) (PNIPA) network is introduced into the gels as the second network. Several main results are obtained from the synthesis and characterization of the gels. For OP-PN gels, their properties depend on the content of both uniformly dispersed Oa-POSS and PNIPA network directly. The increased Oa-POSS and PNIPA network content significantly improves both the strength and resilience of gels. Relatively, the increased Oa-POSS is greatly beneficial to the modulus of gels, and the increased PNIPA network is more favorable to advancing the tensile deformation of gels. The gels with hydrophilic PNIPA network exhibit better swelling ability and remarkable temperature responsiveness, and their volume phase transition temperature can be adjusted by altering the content of Oa-POSS. The deswelling rate of gels increases gradually with the increase of POSS content due to the hydrophobic Si–O skeleton of POSS. Moreover, the enhanced drug loading and sustained release ability of the target drug bovine serum albumin displays great potential for this hybrid gel in the biomedical field.

Polyhedral Oligomeric Silsesquioxanes (POSS)-Based Hybrid Soft Gels: Molecular Design, Material Advantages, and Emerging Applications

“…Scheme for the preparation of IPN hydrogels with the first network based on PNIPAM and the second network based on OAPOSS, SA, and calcium chloride. [Reproduced with permission from ref . Copyright 2019, MDPI, Basel, Switzerland.…”

“…Because of the ionic nature of amino group, OAPOSS-containing hydrogels were capable of providing well-improved drug encapsulation efficiency for certain drugs such as metronidazole and flutamide. , As the strength of ionic interaction could be affected by environmental pH, OAPOSS also made a difference, with regard to the drug release rate and ratio in different simulated tissue fluids. Chen et al took bovine serum albumin (BSA), a common protein macromolecule, as a model drug and studied the IPN hydrogels based on OAPOSS, PNIPAM, and SA . The OAPOSS not only offered ionic and hydrogen bond interactions with the amino acid groups on BSA, but generated hydrophobic interaction with their hydrophobic chains.…”

“…Similar work was reported by Chen et al, where PAAm was replaced by PNIPAM and calcium chloride was added to aid the construction of the second network (Figure 6). 67 With regard to other physical crosslinkers, Zhou et al synthesized novel octa-functional POSS molecules bearing 32 hydroxyl groups, called POSS-AH in the article, via hydrolytic condensation, and prepared PAA hydrogels through a combination of chemical and physical crosslinking (Figure 7). 68 In the early stage of reaction, AA monomers polymerized into linear chains via KPS initiated FRP at 60 °C and entangled around the multihydroxyl POSS through hydrogen-bond and ionic interactions.…”

“…Chen et al took bovine serum albumin (BSA), a common protein macromolecule, as a model drug and studied the IPN hydrogels based on OAPOSS, PNIPAM, and SA. 67 The OAPOSS not only offered ionic and hydrogen bond interactions with the amino acid groups on BSA, but generated hydrophobic interaction with their hydrophobic chains. As a result, the burst release phenomenon was significantly weakened by POSS, and controlled sustained release of BSA within a period as long as 20 days was observed.…”

POSS-Based Polymers

“…Furthermore, they observed that the gels with a hydrophilic PNIPA network exhibited better swelling ability and remarkable temperature responsiveness, and their volume phase transition temperature can be adjusted by altering the content of Oa-POSS. The deswelling rate of gels increases gradually with the increase of POSS content due to the hydrophobic Si–O skeleton of POSS [5].…”