Development of egg white protein aerogels as new matrix material for microencapsulation in food

In vitro digestion of starch and protein aerogels generated from defatted rice bran via supercritical carbon dioxide drying

This study investigated the in vitro digestibility of starch and protein aerogels produced from defatted rice bran (DRB), an underutilized rice processing byproduct, using supercritical carbon dioxide (SC-CO2) drying. The extracted starch (i.e., purified starch), crude starch, and proteins were used for the aerogel formation at 15% (w/w) concentration and further characterized. All aerogels exhibited three-dimensional open porous structures with high surface areas of 36-47 m2/g, densities lower than 0.3 g/cm3, and porosities higher than 84%. The starch hydrolyses in starch and crude starch aerogels were 86 and 73%, respectively, while the protein hydrolysis in protein aerogels reached up to 82% after sequential oral, gastric, and intestinal digestion. Thus, the hydrolysis rates achieved in simulated digestions suggest that the developed aerogels from DRB have the potential to serve as vehicles for delivering bioactive compounds and add value to the underutilized DRB.

Composite hydrogels based on deep eutectic solvents and lysine for pressure sensors and adsorption of Fe3

This study explored the preparation of a novel composite hydrogel based on deep eutectic solvent (DES) with lysine (Lys) and its application in pressure sensing and Fe3+ adsorption. DES was synthesized from acrylamide (AM) and urea (U) as hydrogen bond donors (HBD) with choline chloride (ChCl) as hydrogen bond acceptor (HBA), and Lys was used as a functional filler, and Lys/P(AM-U-ChCl) composite hydrogels were successfully prepared by frontal polymerization (FP) method. The structure of the hydrogels was characterized in depth using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The effects of Lys content on the mechanical properties, pH-responsive behavior, pressure-sensitive properties, and Fe3+ adsorption capacity of the hydrogels were further analyzed. It was found that the introduction of Lys significantly improved the compressive and pressure-sensitive properties of the hydrogels. The composite hydrogels exhibited excellent swelling equilibrium rates at different pH values. The capacitance change of the hydrogel with 0.5 wt% Lys at 200 g pressure was 2.12-fold higher than that of the hydrogel without Lys addition, and the adsorption efficiency of the hydrogel for Fe3+ was greatly enhanced. This study provides a new idea for the functionalized design of composite hydrogels and demonstrates their great application prospects in high-performance pressure sensors and heavy metal ion adsorption.

Particulate bioaerogels for respiratory drug delivery

The bioaerogel microparticles have been recently developed for respiratory drug delivery and attract fast increasing interests. These highly porous microparticles have ultralow density and hence possess much reduced aerodynamic diameter, which favour them with greatly enhanced dispersibility and improved aerosolisation behaviour. The adjustable particle geometric dimensions by varying preparation methods and controlling operation parameters make it possible to fabricate bioaerogel microparticles with accurate sizes for efficient delivery to the targeted regions of respiratory tract (i.e. intranasal and pulmonary). Additionally, the technical process can provide bioaerogel microparticles with the opportunities of accommodating polar, weak polar and non-polar drugs at sufficient amount to satisfy clinical needs, and the adsorbed drugs are primarily in the amorphous form that potentially can facilitate drug dissolution and improve bioavailability. Finally, the nature of biopolymers can further offer additional advantageous characteristics of improved mucoadhesion, sustained drug release and subsequently elongated time for continuous treatment on-site. These fascinating features strongly support bioaerogel microparticles to become a novel platform for effective delivery of a wide range of drugs to the targeted respiratory regions, with increased drug residence time on-site, sustained drug release, constant treatment for local and systemic diseases and anticipated better-quality of therapeutic effects.

Unravelling the functionality of anionic and non-ionic plant seed gums on milk protein cryogels conveying Lacticaseibacillus rhamnosus GG

Cryogels offer a promising macroporous platform that can be employed as either a functional ingredient in food composites or a colloidal template for incorporating bioactives, including probiotic living cells. The aim of the present work is to explore the functionality of two plant seed polysaccharides, flaxseed gum (FG) and alfalfa galactomannan (AAG), in individual and combined (1:1 ratio) milk protein-based cryogels, namely sodium caseinate (NaCas) and whey protein isolate (WPI). These cryogels were created by freeze-drying hydrogels formed via L.rhamnosus GG - a human gut-relevant probiotic strain - fermentation. Our findings showed that including gum in the composition limited volume contraction during lyophilisation, reduced macropore size and thickened cryogel skeleton vessels. Furthermore, gum-containing cryogels displayed improved thermal stability and slower water disintegration rates. The AAG-stabilised cryogels specifically showed a notable reduction in monolayer water content compared to FG. From a mechanistic viewpoint, AAG influenced the physicochemical and microstructural properties of the cryogels, most probably via its self-association during cryogenic processing, promoting the development of intertwined protein-gum networks. FG, on the other hand, enhanced these properties through electrostatic complexation with proteins. Cryogels made from protein-polysaccharide blends exhibited promising techno-functional properties for enhancing and diversifying food product innovation.

Hybrid and Single-Component Flexible Aerogels for Biomedical Applications: A Review

The inherent disadvantages of traditional non-flexible aerogels, such as high fragility and moisture sensitivity, severely restrict their applications. To address these issues and make the aerogels efficient, especially for advanced medical applications, different techniques have been used to incorporate flexibility in aerogel materials. In recent years, a great boom in flexible aerogels has been observed, which has enabled them to be used in high-tech biomedical applications. The current study comprises a comprehensive review of the preparation techniques of pure polymeric-based hybrid and single-component aerogels and their use in biomedical applications. The biomedical applications of these hybrid aerogels will also be reviewed and discussed, where the flexible polymeric components in the aerogels provide the main contribution. The combination of highly controlled porosity, large internal surfaces, flexibility, and the ability to conform into 3D interconnected structures support versatile properties, which are required for numerous potential medical applications such as tissue engineering; drug delivery reservoir systems; biomedical implants like heart stents, pacemakers, and artificial heart valves; disease diagnosis; and the development of antibacterial materials. The present review also explores the different mechanical, chemical, and physical properties in numerical values, which are most wanted for the fabrication of different materials used in the biomedical fields.

Aerogel-Like Material Based on PEGylated Hyperbranched Polymethylethoxysiloxane

Aerogels are a class of materials that have gained increasing attention over the past several decades due to their exceptional physical and chemical properties. These materials are highly porous, with a low density and high surface area, allowing for applications such as insulation, catalysis, and energy storage. However, traditional aerogels, such as pure silica aerogels, suffer from brittleness and fragility, which limit their usefulness in many applications. Herein, we have addressed this problem by using organosilicon compounds, namely polymethylsilsesquioxane derivatives, for the synthesis of aerogel-like materials. Specifically, we have developed a novel approach involving surfactant-free synthesis of microcapsules from partially PEGylated hyperbranched polymethylethoxysiloxane. Due to the highly diphilic nature of these compounds, they readily concentrate at the oil/water interface in aqueous emulsions encapsulating oil droplets. During the subsequent condensation, the organosilicon precursor is consumed for hexane encapsulation (yielding hollow microcapsules) followed by the formation of a continuous condensed phase. Concurrently, methyl groups ensure the hydrophobicity of the resulting materials, which eliminates the need of using additional reagents for their hydrophobization.

Optimising Soy and Pea Protein Gelation to Obtain Hydrogels Intended as Precursors of Food-Grade Dried Porous Materials

Dried porous materials based on plant proteins are attracting large attention thanks to their potential use as sustainable food ingredients. Nevertheless, plant proteins present lower gelling properties than animal ones. Plant protein gelling could be improved by optimising gelation conditions by acting on protein concentration, pH, and ionic strength. This work aimed to systematically study the effect of these factors on the gelation behaviour of soy and pea protein isolates. Protein suspensions having different concentrations (10, 15, and 20% w/w), pH (3.0, 4.5, 7.0), and ionic strength (IS, 0.0, 0.6, 1.5 M) were heat-treated (95 °C for 15 min) and characterised for rheological properties and physical stability. Strong hydrogels having an elastic modulus (G') higher than 10³ Pa and able to retain more than 90% water were only obtained from suspensions containing at least 15% soy protein, far from the isoelectric point and at an IS above 0.6 M. By contrast, pea protein gelation was achieved only at a high concentration (20%), and always resulted in weak gels, which showed increasing G' with the increase in pH and IS. Results were rationalised into a map identifying the gelation conditions to modulate the rheological properties of soy and pea protein hydrogels, for their subsequent conversion into xerogels, cryogels, and aerogels.

Preparation of Protein Aerogel Particles for the Development of Innovative Drug Delivery Systems

The research was oriented towards the preparation of aerogel particles based on egg white and whey protein isolate using various dispersion methods: dripping, spraying, and homogenization. Based on the results of analytical studies, the most appropriate samples were selected to obtain aerogels loaded with the drug. The results of the experimental research were used to study methods for obtaining nasal drug delivery systems based on aerogels. Protein aerogels were obtained by thermal gelation followed by supercritical drying. The obtained particles of protein aerogels have a specific surface area of up to 350 m²/g with a pore volume of up to 2.9 cm³/g, as well as a porosity of up to 95%. The results of experimental studies have shown that changing the dispersion method makes it possible to control the structural characteristics of protein aerogel particles. The results of the studies were applied to obtain innovative nasal drug delivery systems for the treatment of socially significant diseases. Analytical studies were conducted to determine the amount and state of adsorbed drugs in protein aerogel particles, as well as in vivo experiments on the distribution of clomipramine in blood plasma and brain tissue of rats to study the pharmacokinetics and bioavailability of the resulting drug-loaded protein aerogel.

Egg white protein-based delivery system for bioactive substances: a review

Some bioactive substances in food have problems such as poor solubility, unstable chemical properties and low bioavailability, which limits their application in functional food. Recently, many egg white protein-based delivery carriers have been developed to improve the chemical stability, biological activity and bioavailability of bioactive substances. This article reviewed the structure and properties of several major egg white proteins commonly used to construct bioactive substance delivery systems. Several common carrier types based on egg white proteins, including hydrogels, emulsions, micro/nanoparticles, aerogels and electrospinning were then introduced. The biological functions of common bioactive substances, the limitations, and the role of egg white protein-based delivery systems were also discussed. At present, whole egg white protein, ovalbumin and lysozyme are most widely used in delivery systems, while ovotransferrin, ovomucoid and ovomucin are less developed and applied. Egg white protein-based nanoparticles are currently the most commonly used delivery carriers. Egg white protein-based hydrogels, emulsions, and microparticles are also widely used. Future research on the application of various egg white proteins in developed new delivery systems will provide more choices for the delivery of various bioactive substances.

Effects of Grafting Degree on the Physicochemical Properties of Egg White Protein-Sodium Carboxymethylcellulose Conjugates and Their Aerogels

To improve the mechanical strength and oil-loading performances of egg white protein (EWP) aerogel, the effects of different grafting degrees on the modification of EWP by sodium carboxymethylcellulose (CMC-Na) were investigated. After different dry-heat treatment durations (0, 12, 24, 36, and 48 h), the EWP/CMC-Na conjugates with different grafting degrees (noted as EC0, EC12, EC24, EC36, and EC48, respectively) were obtained. Subsequently, the physicochemical properties of the conjugates, as well as the microstructure, mechanical properties, pore parameters, emulsification properties and oil-carrying properties of the conjugated aerogels, were characterized. The results showed that EC12 (with a grafting degree of 8.35%) aerogel possessed a uniform structure, the largest specific surface area, and the best emulsification performance. This facilitated a more robust aerogel (2.05 MPa) with nearly three times the mechanical strength of EWP aerogel. Moreover, this had a positive influence on the efficient loading and stable retention of oil. EC12 aerogel thus achieved an oil absorption capacity of 5.46 g/g aerogel and an oil holding capacity of 31.95%, and both values were nearly 1.7 times higher than those of EWP aerogel. In general, the EWP-based aerogel with a grafting degree of 8.35% had the best mechanical and oil-loading properties.

Bio-aerogels: Fabrication, properties and food applications

Traditional inorganic aerogels sustainability, biodegradability, and environmental safety concerns have driven researchers to find their safe green alternatives. Recently, interest in the application of bio-aerogels has rapidly increased in the food industry due to their unique characteristics such as high specific surface area and porosity, ultralow density, tunable pore size and morphology, and superior properties (physicochemical, mechanical, and functional). Bio-aerogels, a special category of highly porous unique materials, fabricated by the sol-gel method followed by drying processes, comprising three-dimensional networks of interconnected biopolymers (e.g., polysaccharides and proteins) with numerous air-filled pores. The production of bio-aerogels begins with the formation of a homogeneously dispersed precursor solution, followed by gelation and wet gel drying procedures by employing special drying techniques including atmospheric-, freeze-, and supercritical drying. Due to their special properties, bio-aerogels have emerged as sustainable biomaterial for many industrial applications, i.e., encapsulation and controlled delivery, active packaging, heavy metals separation, water and air filtration, oleogels, and biosensors. Bio-aerogels are low-cost, biocompatible, and biodegradable sustainable material that can be used in improving the processing, storage, transportation, and bioavailability of food additives, functional ingredients, and bioactive substances for their health benefits with enhanced shelf-life.

Versatile Route for Multifunctional Aerogels Including Flaxseed Mucilage and Nanocrystals

Preparation of low density monolithic and free-standing organic-inorganic hybrid aerogels of various properties is demonstrated using green chemistry from a biosafe natural source (flaxseed mucilage) and freeze-casting and subsequent freeze drying. Bio-aerogels, luminescent aerogels and magneto-responsive aerogels were obtained by combination of the flaxseed mucilage with different types of nanoparticles. Moreover, the aerogels are investigated as possible drug release system using curcumin as a model. Various characterization techniques like thermogravimetric analysis, nitrogen physisorption, electron microscopy, UV/Vis absorption and emission spectroscopy, bulk density and mechanical measurements as well as in vitro release profile measurements are employed to investigate the obtained materials. The flaxseed-inspired organic-inorganic hybrid aerogels exhibit ultra-low densities of as low as 5.6 mg/cm³ for 0.5% (w/v) mucilage polymer, a specific surface area of 4 to 20 m² /g, high oil absorption capacity (23 g/g) and prominent compressibility. The natural biopolymer technique leads to low cost and biocompatible functional lightweight materials with tunable properties (physicochemical and mechanical) and significant potential for applications as supporting or stimuli responsive materials, carriers, reactors, microwave, and electromagnetic radiation protective (absorbing) material as well as in drug delivery and oil absorption. This article is protected by copyright. All rights reserved.

Conversion of Whey Protein Aerogel Particles into Oleogels: Effect of Oil Type on Structural Features

Protein aerogel particles prepared by supercritical-CO₂-drying (SCD) of ground whey protein (WP) hydrogels (20% w/w, pH 5.7) were converted into oleogels by dispersion in selected edible oils (castor, cod liver, corn, flaxseed, MCT, peanut and sunflower oil). The obtained oleogels were analysed for oil content, microstructure, rheological properties, and ATR-FTIR spectra. Except for castor oil, solid-like, plastic materials with comparable composition (80% oil, 20% WP) and rheological properties (G′~3.5 × 10⁵ Pa, G″~0.20 × 10⁵ Pa, critical stress~800 Pa, tanδ~0.060) were obtained. Optical and confocal microscopy showed that the generated structure was associated with the capillary-driven absorption of oil into the porous aerogel particles interconnected via particle-particle interactions. In this structure, the oil was stably entrapped. Results evidenced the reduced role of edible oil characteristics with the exception of castor oil, whose high polarity probably favoured particle–oil interactions hindering particle networking. This work demonstrates that WP aerogels could be regarded as versatile oleogel templates allowing the structuring of many edible oils into solid-like materials.

Aerogels are not regulated as nanomaterials, but can be assessed by tiered testing and grouping strategies for nanomaterials

Aerogels contribute to an increasing number of novel applications due to many unique properties, such as high porosity and low density. They outperform most other insulation materials, and some are also useful as carriers in food or pharma applications. Aerogels are not nanomaterials by the REACH definition but retain properties of nanoscale structures. Here we applied a testing strategy in three tiers. In Tier 1, we examined a panel of 19 aerogels (functionalized chitosan, alginate, pyrolyzed carbon, silicate, cellulose, polyurethane) for their biosolubility, and oxidative potential. Biosolubility was very limited except for some alginate and silicate aerogels. Oxidative potential, as by the ferric reduction ability of human serum (FRAS), was very low except for one chitosan and pyrolyzed carbon, both of which were <10% of the positive control Mn₂O₃. Five aerogels were further subjected to the Tier 2 alveolar macrophage assay, which revealed no in vitro cytotoxicity, except for silicate and polyurethane that induced increases in tumor necrosis factor α. Insufficiently similar aerogels were excluded from a candidate group, and a worst case identified. In the Tier 3 in vivo instillation, polyurethane (0.3 to 2.4 mg) elicited dose-dependent but reversible enzyme changes in lung lavage fluid on day 3, but no significant inflammatory effects. Overall, the results show a very low inherent toxicity of aerogels and support a categorization based on similarities in Tier 1 and Tier 2. This exemplifies how nanosafety concepts and methods developed on particles can be applied to specific concerns on advanced materials that contain or release nanostructures.

Fabrication of a Novel Protein Sponge with Dual-Scale Porosity and Mixed Wettability Using a Clean and Versatile Microwave-Based Process

An open-porous protein sponge with mixed wettability is presented made entirely from whey proteins and with promising applications in biomedicine, pharmaceutical, and food industry. The fabrication relies on an additive-free, clean and scalable process consisting of foaming followed by controlled microwave-convection drying. Volumetric heating throughout the matrix induced by microwaves causes fast expansion and elongation of the foam bubbles, retards crust formation and promotes early protein denaturation. These effects counteract collapse and shrinkage typically encountered in convection drying of foams. The interplay of high protein content, tailored gas incorporation and controlled drying result in a dried structure with dual-scale porosity composed of open macroscopic elongated foam bubbles and microscopic pores in the surrounding solid lamellae induced by water evaporation. Due to the insolubility and mixed wettability of the denatured protein network, polar and non-polar liquids are rapidly absorbed into the interconnected capillary system of the sponge without disintegrating. While non-watery liquids penetrate the pores by capillary suction, water diffuses also into the stiff protein matrix, inducing swelling and softening. Consequently, the water-filled soft sponge can be emptied by compression and re-absorbs any wetting liquid into the free capillary space.

Preparation of a novel double crosslinked chitin aerogel via etherification with high strength

In this study, we introduced a novel double crosslinked chitin aerogel via etherification with EGDE for mechanical reinforcement. Samples with different EGDE: chitin weight ratios from 0 to 1.5:1 were fabricated through chitin dissolution in KOH/urea aqueous solution, ethanol neutralization and washing, and supercritical CO₂ drying. Both the physical and chemical crosslinking maintained the high porosity and light weight of chitin aerogels. The morphology under SEM has shown the close-ended and denser fibrils alignment for EGDE crosslinked aerogels and the mesoporous and macroporous structure induced by emulsion effect from excessive EGDE. FTIR characterization was conducted for chemical structure analysis. Compressive testing showed an increase of 247 % compressive strength at 10 % strain and 243 % modulus could be achieved at 1.0 EGDE samples. TGA results revealed a delayed thermal degradation for the chemically crosslinked samples. This study demonstrates EGDE an effective chemical crosslinker for reinforced chitin aerogels.

Study on the possibility of developing food-grade hydrophobic bio-aerogels by using an oleogel template approach

The feasibility of producing food-grade hydrophobic bio-aerogels by supercritical-carbon dioxide (SC-CO₂) extraction of oil from oleogels was investigated for the first time. Medium chain triglycerides (MCT) oil was gelled using ethylcellulose (EC) at increasing concentration (10, 15, 20% w/w) and grade (EC20, 45, 100), eventually in combination with fillers. Different SC-CO₂ oil extraction procedures were tested. The acquired results show that both oleogel formulation and extraction conditions can steer the EC scaffold structure. The increase in EC concentration and grade resulted in oleogels more structurally stable to SC-CO₂ extraction. The application of a pulsed extraction procedure allowed obtaining a low-density (0.39 ​g/cm³) EC scaffold presenting 60% oil. Addition of freeze dried lettuce powder improved macrostructure homogeneity. The obtained results lay the foundations for developing food-grade hydrophobic bio-aerogels, which are expected to present unique oil absorption and bioactive delivery features.

Biorefinery Approach for Aerogels

According to the International Energy Agency, biorefinery is "the sustainable processing of biomass into a spectrum of marketable bio-based products (chemicals, materials) and bioenergy (fuels, power, heat)". In this review, we survey how the biorefinery approach can be applied to highly porous and nanostructured materials, namely aerogels. Historically, aerogels were first developed using inorganic matter. Subsequently, synthetic polymers were also employed. At the beginning of the 21st century, new aerogels were created based on biomass. Which sources of biomass can be used to make aerogels and how? This review answers these questions, paying special attention to bio-aerogels' environmental and biomedical applications. The article is a result of fruitful exchanges in the frame of the European project COST Action "CA 18125 AERoGELS: Advanced Engineering and Research of aeroGels for Environment and Life Sciences".

Effect of Ethanol on the Textural Properties of Whey Protein and Egg White Protein Hydrogels during Water-Ethanol Solvent Exchange

This study aims at investigating the effect of ethanol (EtOH) on the textural properties of whey protein and egg white protein hydrogels. The hydrogels were produced by thermally induced gel formation of aqueous protein solutions. The water contained in the gel network was subsequently exchanged by EtOH to assess structural changes upon exposure of hydrogels to ethanolic aqueous phases. The textural properties of the hydrogel and alcogel samples were analyzed by uniaxial compression tests. For both protein sources, the hardness increased exponentially when pH and EtOH concentration were increased. This increase correlated with a shrinkage of the gel samples. The gel texture was found to be elastic at low EtOH concentrations and became stiff and hard at higher EtOH concentrations. It was found that the solvent exchange influences the ion concentration within the gels and, therefore, the interactions between molecules in the gel structure. Non-covalent bonds were identified as substantially responsible for the gel structure.

Starch-Based Aerogels Obtained via Solvent-Induced Gelation

In this work, the ability of several solvents to induce gel formation from amylomaize starch solubilized in dimethyl sulfoxide (DMSO) was investigated. The formed gels were subjected to solvent exchange using ethanol and dried with supercritical carbon dioxide (sc-CO₂) to obtain the aerogels. The influence of starch concentration (3–15 wt%) and solvent content (20–80 wt%) on gel formation was also studied. It was demonstrated that the gelation of starch in binary mixtures of solvents can be rationalized by Hansen Solubility Parameters (HSP) revealing a crucial hole of hydrogen bonding for the gel’s strength, which is in agreement with rheological measurements. Only the addition of water or propylene glycol to starch/DMSO solutions resulted in strong gels at a minimum starch and solvent content of 7.5 wt% and 50 wt%, respectively. The resulting aerogels showed comparably high specific surface areas (78–144 m² g⁻¹) and low envelope densities (0.097–0.203 g cm⁻³). The results of this work indicate that the HSP parameters could be used as a tool to guide the rational selection of water-free gelation in starch/DMSO systems. In addition, it opens up an attractive opportunity to perform starch gelation in those solvents that are miscible with sc-CO₂, avoiding the time-consuming step of solvent exchange.

Rheological and structural properties of oleogel base on soluble complex of egg white protein and xanthan gum

Oleogels can be used to provide solid-like properties without using high levels of saturated fatty acids. In this study, the edible oleogels structure developed based on egg white protein (EWP) (5%) and xanthan gum (XG) (0%, 1%, 0.5%, and 0.75% wt/wt) complex by using aerogels system as a template for oleogel preparation. The effect of pH on the EWP-XG mixture indicated the creation of a soluble complex of EWP-XG in pH 5.5. The Fourier-transform infrared spectroscopy confirmed the interaction between EWP and XG. The amount of absorbed oil was considerably higher in EWP-XG aerogels. SEM showed a soft surface in EWP 5% aerogel, which can be the reason for its less oil absorption. The aerogel and oleogel including more XG concentration had a stronger network structure and created more elastic oleogels. The light microscopy images revealed by increasing of XG concentration, the structure of protein gel mesh became more compact and regular. The XRD patterns of the aerogels did not show any clear differences between crystallinity of the samples. Therefore, it can be concluded that the aerogels based on the structuring of EWP-XG complexes have a high potential as a three-dimensional network for the oil absorption and creating oleogel.

New Trends in Bio-Based Aerogels

(1) Background: The fascinating properties of currently synthesized aerogels associated with the flexible approach of sol-gel chemistry play an important role in the emergence of special biomedical applications. Although it is increasingly known and mentioned, the potential of aerogels in the medical field is not sufficiently explored. Interest in aerogels has increased greatly in recent decades due to their special properties, such as high surface area, excellent thermal and acoustic properties, low density and thermal conductivity, high porosity, flame resistance and humidity, and low refractive index and dielectric constant. On the other hand, high manufacturing costs and poor mechanical strength limit the growth of the market. (2) Results: In this paper, we analyze more than 180 articles from recent literature studies focused on the dynamics of aerogels research to summarize the technologies used in manufacturing and the properties of materials based on natural polymers from renewable sources. Biomedical applications of these bio-based materials are also introduced. (3) Conclusions: Due to their complementary functionalities (bioactivity, biocompatibility, biodegradability, and unique chemistry), bio-based materials provide a vast capability for utilization in the field of interdisciplinary and multidisciplinary scientific research.

Gum tragacanth-polyvinyl alcohol aerogel for oral delivery of silymarin

This study reports for the first time the fabrication of highly porous aerogels of mixed gum tragacanth-polyvinyl alcohol (GT-PVA) for loading and oral delivery of silymarin (SM). Various analytical techniques were used to investigate changes in the physical, textural, mechanical and microstructural properties of aerogels as affected by blending ratio and vacuum impregnation (VI) of SM. Results showed that the mixing ratio of 1:1 led to aerogels of larger surface area (1029.20 m²·g^-1) and superior physicochemical properties. However, at mixing ratio of 3:1 (GT:PVA) higher loading capacity (45.57% ± 2.3%) was obtained. SM loading, on the other hand, had an adverse effect on the porosity, microstructure and physical attributes of aerogels transforming them from meso-porous to macro-porous structures. The release rate of SM in simulated gastrointestinal media was found to follow Korsmeyere-Peppas model.

Structural characterization of oleogels from whey protein aerogel particles

Oleogels intended as fat substitutes were prepared by oil dispersion of aerogel particles obtained through freeze-drying (FD) or supercritical-CO₂-drying (SCD) of whey protein isolate (WPI) hydrogels (20 g/100 g). SEM revealed that freeze-dried particles presented larger dimensions than supercritical-dried ones. The latter also showed higher oil dispersibility, forming aggregates with lower dimension (300 nm) than those formed by freeze-dried particles (700 nm). Both particles presented oil structuring capability. Freeze-dried particles gave a weak oleogel, while supercritical-dried ones gave a strong (G' = 3.1 × 10⁵ Pa) and plastic (critical stress = 723.2 Pa) oleogel, with rheological features comparable to those of traditional fats. These results can be explained based on the lower aggregation induced by SCD and on the higher capacity of supercritical-dried particles to form a network in oil through hydrophilic interactions, as suggested by FTIR. Therefore, WPI aerogel particles show the potentiality to be used as food ingredients to prepare oleogels with tailor-made physical properties.

Alginate-Based Aerogel Particles as Drug Delivery Systems: Investigation of the Supercritical Adsorption and In Vitro Evaluations

The present work focuses on the preparation of alginate-based aerogels in the form of particles for their further study as potential drug delivery systems (solid dosage forms). The dripping method was used to prepare certain gel particles, and supercritical drying was used to obtain final alginate-based aerogel particles. Three model active substances (ketoprofen, nimesulide, loratadine) were impregnated into the obtained aerogels using the supercritical adsorption process. Using the method of X-ray analysis, it was shown that the in the obtained drug-loaded aerogels the corresponding active substances are in an amorphous state, and the stability of this state after six months of storage is confirmed. In vitro dissolution tests for obtained drug-loaded aerogels was performed. For each sample, an appropriate dissolution medium (with certain pH) was determined. In vitro investigations showed the increasing of the release rate for all model active substances. Time was required to release and dissolve 50% of the active drug from drug-loaded aerogels (T1/2), reduced in comparison with pure active drugs in crystalline form. Obtained results provide insight into the application of alginate-based aerogel particles as a drug delivery system to improve pharmacokinetic properties of certain active drugs.