Inorganic–organic hybrid alginate beads with LCST near human body temperature for sustained dual‐sensitive drug delivery

Abstract

In order to obtain dual-stimuli-responsive (temperature/pH) alginate beads that exhibit LCST close to human body temperature for sustained drug release applications, poly (NIPAAm-co-AAm) hydrogel (with LCST 37.5-C) were selected and associated with calcium alginate to prepare inorganic--organic hybrid biomineralized polysaccharide alginate beads via a one-step method in this paper. Scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer (EDS) results demonstrated that calcium phosphate could not only be found in the surface but also in the cross-section of biomineralized polysaccharide beads. Both equilibrium swelling and indomethacin release behavior were found to be pH-and thermo-responsive. In addition, indomethacin release profile could be sustained with a inorganic--organic hybrid membrane: the release amount reached 96% within 4 hr for the unmineralized beads, while a drug release of only 64% obtained after subjecting the biomineralized polysaccharide beads to the same treatment. These results indicate that the biomineralized polysaccharide membrane could prevent the permeability of the encapsulated drug and reduce the drug release rate effectively. The studied system has the potential to be used as an effective smart sustainable delivery system for biomedical applications.

Drug release behavior of a pH/temperature sensitive calcium alginate/poly(N-acryloylglycine) bead with core-shelled structure

“…This higher release rate may be related to the higher swelling ratio of the beads and the weak H-bonding interaction between drug and polymer network in the neutral PBS. A similar release behavior has also been reported in an inorganic-organic hybrid alginate bead and N-succinyl chitosan/alginate hydrogel systems [23,24]. From the more practical point of view, the bead can overpass the acidity medium of gastric fluid without releasing substantial amounts of drug molecules, but release a mass of drug in the small intestine.…”

“…Among the smart materials, pH-and temperature-sensitive hydrogels have been paid more attentions because the two physiological factors are very important for the human body [18][19][20][21]. To prepare a stimulus-sensitive polymeric hydrogel with biocompatiblity and biodegradation, many efforts have been made to combine the thermo-sensitive polymers with some biopolymers such as β-cyclodextrin, starch, alginate and chitosan [22][23][24]. Alginate is a kind of water-soluble linear polysaccharide separated from brown sea weed and is composed of alternating blocks of 1-4 linked α-Lguluronic and β-D-mannuronic acid residues.…”

Hydrophobically modified biomineralized polysaccharide alginate membrane for sustained smart drug delivery

“…The deposition in porous alginate/chitosan polyelectrolyte complexes around the resulting membrane is coupled with a controlled precipitation of calcium phosphate arising from counter-diffusion of ions across the polysaccharide interface at a suitable pH value [13,14,17]. The biomineralized polysaccharide layer hardens with time due to the deposition of calcium phosphate but remains permeable to Ca 2+ ions, such that the membranes are also internally stabilized due to cross-linking of the alginate network.…”

“…After the introduction of sodium palmitate, strong absorptions at 2856 and 2919 cm −1 appeared as a result of the introduction of hydrophobic methyl and methylene group. Additionally, three strong absorptions at around 1033 cm −1 , 601 cm −1 and 566 cm −1 assignable to the P O bonds could be observed for alginate/sodium palmitate/BP membranes, suggesting the formation of CaHPO 4 within the membrane [13,14]. Fig.…”

“…Previous studies have shown biomineralized polysaccharide hybrid structure could improve the mechanical strength and sustained release behaviour of alginate beads [13][14][15]. Moreover, biomineralized polysaccharide hybrid materials are likely to be of generic importance in the design of biocompatible microcapsules because they often exhibit complementary properties, and have potential applications for cell growth, drug delivery and the implications for tissue engineering [16][17][18].…”