Crosslinker-Free Hyaluronic Acid Aerogels

Aguilera-Bulla, Daniel; Legay, Laurianne; Buwalda, Sytze J.; Budtova, Tatiana

doi:10.1021/acs.biomac.2c00207

Cited by 9 publications

(21 citation statements)

References 47 publications

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“…No larger pores are visible, suggesting that, at pH 2.5, the interactions between HA chains are sufficiently strong to prevent deformation of the network and avoid the creation of large pores by growing ice crystals. In line with previous results, 33 the use of ethanol as nonsolvent resulted in the highest surface areas thanks to the higher affinity of HA with ethanol in comparison with acetone (Figure 5, left and right). An increase in HA concentration results in a slight increase of the specific surface area (Figure 5).…”

Section: Resultssupporting

confidence: 92%

“…Higher shrinkage was observed for samples prepared with acetone as nonsolvent (Figure 3); the same trend was observed for materials made with 1 FT cycle (Figure S3). This can be ascribed to the lower affinity of HA with acetone, compared to ethanol, as indicated by the total solubility parameters of HA, ethanol, and acetone (35.8, 26.5, and 19.9 MPa 1/2 , respectively 33 ), leading to a "harsher" coagulation. No particular influence of the number of FT cycles on HA shrinkage and density was recorded (compare Figures 3 and S3, Figures 4 and S4).…”

Section: Resultsmentioning

confidence: 99%

“…The molecular weight is (1.5−2.2) × 10 6 g/mol as given by the manufacturer and 1.2 × 10 6 g/mol as determined from intrinsic viscosity. 33 Acetone (≥99%), absolute ethanol (≥99%), hydrochloric acid (HCl, 32%, analytical grade), sodium hydroxide (NaOH), sodium chloride (NaCl), potassium chloride (KCl), and monopotassium phosphate (KH 2 PO 4 ) were from Fisher Chemical (Illkirch-Graffenstaden, France). Disodium phosphate (Na 2 HPO 4 ) was from Alfa Aesar (Kandel, Germany).…”

Section: Methodsmentioning

confidence: 99%

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Hyaluronic Acid Aerogels Made Via Freeze–Thaw-Induced Gelation

2023

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The biodegradability, biocompatibility, and bioactivity of hyaluronic acid (HA), a natural polysaccharide, combined with the low density, high porosity, and high specific surface area of aerogels attract interest for biomedical applications such as wound dressings. In this work, physically cross-linked HA aerogels were prepared via the freeze–thaw (FT) induced gelation method, solvent exchange, and drying with supercritical CO2. The morphology and properties of HA aerogels (volume shrinkage, density, and specific surface area) were investigated as a function of several process parameters: HA concentration, solution pH, number of FT cycles, and type of nonsolvent used during solvent exchange. We demonstrate that the HA solution pH plays a key role in the aerogel formation, as not all conditions result in materials with high specific surface area. HA aerogels were of low density (<0.2 g/cm3), high specific surface area (up to 600 m2/g), and high porosity (≥90%). Scanning electron microscopy pictures revealed that HA aerogels present a porous structure with meso- and small macropores. The results show that HA aerogels are promising biomaterials with tunable properties and internal structure that offer high potential as, e.g., wound dressings.

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Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Hyaluronic Acid Aerogels Made Via Freeze–Thaw-Induced Gelation

2023

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“…It indicates that starches adsorb theophylline from ethanol. We suppose that this is due to a better affinity of theophylline to starch as compared to ethanol, as confirmed by the values of solubility parameters of theophylline 33 (23.53 MPa 1/2 ), starch 34 (24 MPa 1/2 ), and ethanol 35 (26.5 MPa 1/2 ). Experimental loading capacities of starch alcogels (eq 2) are presented in Figure 3a.…”

Section: ■ Results and Discussionmentioning

confidence: 66%

Starch Alcogels, Aerogels, and Aerogel-like Xerogels: Adsorption and Release of Theophylline

Zou

Budtova

2023

ACS Sustainable Chem. Eng.

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Starch is one of the most abundant and biodegradable natural polysaccharides; it has been widely used in pharmaceutics in tablets, as a disintegrant, or as a porous carrier. In this work, starches in different formsalcogels, aerogels, and low-vacuum-dried materials (named xerogels)were designed and tested as carriers of theophylline. The influence of the starch amylose/amylopectin ratio, concentration in solution, retrogradation time, and drying method (supercritical CO2 drying for aerogels, low-vacuum drying for xerogels) on materials’ density, specific surface area, and morphology was investigated. The precursors before drying were starch alcogels made by water-to-ethanol exchange in retrograded hydrogels. Starch alcogels were loaded with theophylline via impregnation. Loading capacities and efficiencies of alcogels, aerogels, and xerogels were determined, and release of the drug from xerogels and aerogels was evaluated. Two remarkable phenomena were obtained: (1) The low-vacuum drying method resulted in starch aerogel-like materials; i.e., xerogels with low densities and specific surface areas above 100 m2/g. (2) Starch alcogels adsorbed theophylline from ethanol resulting in loading efficiency as high as 250%. The results obtained show a new pathway in making aerogel-like polysaccharide materials without drying in supercritical conditions for potential use as drug carriers.

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“…In fact, previous attempts in the literature to obtain HA aerogels without crosslinkers using CO 2 supercritical drying technique and ethanol and acetone as solvents showed that aerogel formation was only possible at low pH (1.5 and 2.5). No aerogels were formed at pH 6 as the HA is deprotonated and no interactions between chains can be produced (the network cannot be formed), so the polymer solution cannot withstand the water-ethanol phase change [ 43 , 44 ].…”

Section: Resultsmentioning

confidence: 99%

Granular Disulfide-Crosslinked Hyaluronic Hydrogels: A Systematic Study of Reaction Conditions on Thiol Substitution and Injectability Parameters

et al. 2023

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Granular polymer hydrogels based on dynamic covalent bonds are attracting a great deal of interest for the design of injectable biomaterials. Such materials generally exhibit shear-thinning behavior and properties of self-healing/recovery after the extrusion that can be modulated through the interactions between gel microparticles. Herein, bulk macro-hydrogels based on thiolated-hyaluronic acid were produced by disulphide bond formation using oxygen as oxidant at physiological conditions and gelation kinetics were monitored. Three different thiol substitution degrees (SD%: 65%, 30% and 10%) were selected for hydrogel formation and fully characterized as to their stability in physiological medium and morphology. Then, extrusion fragmentation technique was applied to obtain hyaluronic acid microgels with dynamic disulphide bonds that were subsequently sterilized by autoclaving. The resulting granular hyaluronic hydrogels were able to form stable filaments when extruded through a syringe. Rheological characterization and cytotoxicity tests allowed to assess the potential of these materials as injectable biomaterials. The application of extrusion fragmentation for the formation of granular hyaluronic hydrogels and the understanding of the relation between the autoclaving processes and the resulting particle size and rheological properties should expand the development of injectable materials for biomedical applications.

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Crosslinker-Free Hyaluronic Acid Aerogels

Cited by 9 publications

References 47 publications

Hyaluronic Acid Aerogels Made Via Freeze–Thaw-Induced Gelation

Hyaluronic Acid Aerogels Made Via Freeze–Thaw-Induced Gelation

Starch Alcogels, Aerogels, and Aerogel-like Xerogels: Adsorption and Release of Theophylline

Granular Disulfide-Crosslinked Hyaluronic Hydrogels: A Systematic Study of Reaction Conditions on Thiol Substitution and Injectability Parameters

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