Silver hydroxyapatite reinforced poly(vinyl alcohol)—starch cryogel nanocomposites and study of biodegradation, compressive strength and antibacterial activity
Abstract:In the present work polyvinyl alcohol‐starch/silver hydroxyapatite (PVA‐starch/AgHap) cryogel nanocomposites were prepared by successive freezing‐thawing of a blend of PVA and starch solutions to fabricate a cryogel followed by its reinforcement with silver hydroxyapatite (AgHap). The prepared macroporous cryogel nanocomposites were characterized by Infra‐red spectroscopy (FTIR), environmental scanning electron microscopy (ESEM), and particle size and charge analysis. The amylase induced enzymatic degradation … Show more
“…Yet, its poor performance causes severe issues of water sensitivity, limited mechanical properties, and high fragility, over time . Its low mechanical properties are major concern, especially when exposed to hydrolytic, oxidative, low, and high temperature conditions . The organic nature of TPS, in terms of easy‐aging and degradation during usage and storage, is also to be considered in food packaging applications because it may result in the reduction of quality and lower shelf life of the TPS‐based products .…”
“…Yet, its poor performance causes severe issues of water sensitivity, limited mechanical properties, and high fragility, over time . Its low mechanical properties are major concern, especially when exposed to hydrolytic, oxidative, low, and high temperature conditions . The organic nature of TPS, in terms of easy‐aging and degradation during usage and storage, is also to be considered in food packaging applications because it may result in the reduction of quality and lower shelf life of the TPS‐based products .…”
“…Many polysaccharides, in their natural or chemically functionalized state, such as chitosan, starch, dextran, cellulose, xanthan, β-glucans, sodium alginate, carrageenans and so forth, have been previously blended with PVA to obtain cryogels [11,12]. Due to their overall hydrophilic character, the addition of polysaccharides (e.g., starch, hydroxyethyl starch) can increase the swelling degree of the blend cryogels up to 300% compared with neat PVA, submitted to identical physical crosslinking operational parameters [13,14]. Chitosan, starch and various glucans, for example, are reported to improve the hydrophilic character, elasticity and flexibility of the hydrogels for wound dressing applications, while also fine-tuning the diffusion coefficient of various active principles (antibiotics, nutraceuticals and so forth) through the polymeric matrix, from 10 −5 -10 −4 mm 2 /min with up to one order of magnitude [15,16].…”
Section: Introductionmentioning
confidence: 99%
“…For m t /m eq ≤ 0.5, Equation (11) permits the determination of the so-called "early-time" diffusion coefficient D e , while Equation (12), valid for m t /m eq > 0.6, permits the determination of the "late-time" diffusion coefficient, D l [73]. A complementary modeling method for the early-time approximation is the power-law approach introduced by Peppas and depicted in Equation (13), where k is a constant indicating the swelling rate and n denotes the type of transport mechanism. When n is equal to 0.5 (and according to some researchers ≤ 0.5), the transport rate of the solute into the hydrogel is Fickian, i.e., the solvent penetration rate is higher than the polymer chain relaxation rate (Equation (12) assumes a Fickian diffusion, i.e., n = 0.5 and k = 4 √ D e /δ √ π).…”
This paper discusses the structure morphology and the thermal and swelling behavior of physically crosslinked hydrogels, obtained from applying four successive freezing–thawing cycles to poly (vinyl alcohol) blended with various amounts of κ-carrageenan. The addition of carrageenan in a weight ratio of 0.5 determines a twofold increase in the swelling degree and the early diffusion coefficients of the hydrogels when immersed in distilled water, due to a decrease in the crystallinity of the polymer matrix. The diffusion of water into the polymer matrix could be considered as a relaxation-controlled transport (anomalous diffusion). The presence of the sulfate groups determines an increased affinity of the hydrogels towards crystal violet cationic dye. A maximum physisorption capacity of up to 121.4 mg/g for this dye was attained at equilibrium.
“…Composite materials are made not by the simple blending (mixing) of two or more polymers but by incorporating another type of material, such as nano-, micro- or macroparticles [ 76 , 142 , 143 ]. The final material will have unique characteristics that can be beneficial for biomedical applications [ 69 , 144 , 145 ].…”
Section: Biodegradable Cryogelsmentioning
confidence: 99%
“…In vitro degradation is usually studied in a buffer or simulated biological media by analyzing the mass loss of the scaffold over time [ 48 , 85 , 151 ]. The simulated degradation conditions may involve chemical hydrolysis, such as in the case of PLLA scaffold [ 151 , 170 ], or induced by adding enzymes [ 69 ]. Temperature, pH and cryogel composition play a key role in the degradation profile.…”
Section: Characterization Of the Degradation Process In Vitro And In Vivomentioning
Cryogels obtained by the cryotropic gelation process are macroporous hydrogels with a well-developed system of interconnected pores and shape memory. There have been significant recent advancements in our understanding of the cryotropic gelation process, and in the relationship between components, their structure and the application of the cryogels obtained. As cryogels are one of the most promising hydrogel-based biomaterials, and this field has been advancing rapidly, this review focuses on the design of biodegradable cryogels as advanced biomaterials for drug delivery and tissue engineering. The selection of a biodegradable polymer is key to the development of modern biomaterials that mimic the biological environment and the properties of artificial tissue, and are at the same time capable of being safely degraded/metabolized without any side effects. The range of biodegradable polymers utilized for cryogel formation is overviewed, including biopolymers, synthetic polymers, polymer blends, and composites. The paper discusses a cryotropic gelation method as a tool for synthesis of hydrogel materials with large, interconnected pores and mechanical, physical, chemical and biological properties, adapted for targeted biomedical applications. The effect of the composition, cross-linker, freezing conditions, and the nature of the polymer on the morphology, mechanical properties and biodegradation of cryogels is discussed. The biodegradation of cryogels and its dependence on their production and composition is overviewed. Selected representative biomedical applications demonstrate how cryogel-based materials have been used in drug delivery, tissue engineering, regenerative medicine, cancer research, and sensing.
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