Starch Aerogel Research Articles

Dual-function starch aerogels: Nutraceutical carriers for iron and folic acid delivery

Iron and folic acid are especially important in pregnancy, where supplementation is often the only path to prevent anemia. Despite the available commercial solutions, the challenges of enhancing nutrient absorption and reducing side effects foster the search for novel approaches. In this work, freeze-dried starch aerogels were developed to act as nutraceutical carriers for co-delivery and tested under simulated digestion conditions. Iron and folic acid were loaded into starch gels, both separately and mixed. Iron presented a faster release than folic acid in intestinal conditions, reaching 75–80 % after 10 and 90 min, respectively. Molecular modeling suggests that folic acid interacts with amylose agglomerates in water by hydrogen bonds, probably delaying its release. Co-delivery of these nutraceuticals seems to not affect the release behavior. The Korsmeyer-Peppas kinetic model fits well to all release profiles. The proposed starch aerogel is a promising solution and further development can increase its competitiveness against conventional supplements.

Increasing the bioavailability of curcumin using a green supercritical fluid technology-assisted approach based on simultaneous starch aerogel formation-curcumin impregnation

A green approach based on simultaneous starch aerogel formation-curcumin impregnation via supercritical fluid technology was used to increase the bioavailability of curcumin. The loading amounts of curcumin were 16.4, 21.4, and 24.9 mg/g of aerogel for the 25% Amyl-loaded, 55% Amyl-loaded, and 72% Amyl-loaded samples, respectively. Curcumin-loaded aerogels showed the eventual distribution of curcumin in the hydrophobic area of the internal structure of the aerogels. In vitro gastrointestinal release profiles demonstrated the enhanced curcumin release from the curcumin-loaded aerogel formulations produced by the SC-CO2 technology over free curcumin. After intestinal digestion, the percentage of released curcumin from 25% Amyl-loaded, 55% Amyl-loaded, and 72% Amyl-loaded was 7.2, 12.1, and 12.1%, respectively, while the release of native curcumin was only 0.5%. Caco-2 cell permeation studies revealed superior bioavailability of curcumin from the curcumin-loaded aerogels. Curcumin-loaded aerogels exhibited improved storage stability than free curcumin.

Effective Removal of Methyl Orange Dyes Using an Adsorbent Prepared from Porous Starch Aerogel and Organoclay

Intending to provide efficient and compact wastewater remediation, the present work is exploiting and introducing a novel composite prepared from porous starch aerogel (PSA) and organically modified Ca-montmorillonite (OMMT) for the removal of dyes from aqueous samples. First, potato starch components were used as a hydrolysis precursor to obtain PSA. The organoclay samples were prepared by co-intercalation of octadecylamine (ODA) into Ca-MMT using a low-temperature melting procedure. Composites with different starch-to-organoclay ratios of 10:1, 1:1, and 1:10 were then prepared by a blending process in distilled water and used for methyl orange (MO) uptake. The removal of methyl orange dyes increased with the amount of organoclay in the PSA matrix. Characterization revealed that organoclay synergy improved the PSA surface chemistry, while an important improvement in textural properties and thermal stability was also observed. The composite’s efficiency was demonstrated by high removal capabilities towards MO in most experimental runs, with a maximum adsorption capacity beyond 344.7 mg/g. The fitting result showed that MO adsorption follows a monolayer adsorption model, and chemisorption was the rate-controlling step. Nonetheless, this study proved the great potential of PSA/OMMT in dyeing wastewater treatment. Furthermore, starch modification is proven as an effective approach to enhancing the performance of starch-derived adsorbents.

Effect of starch type and chitosan supplementation on physicochemical properties, morphology, and oil structuring capacity of composite starch bioaerogels

Oleogelation is a novel fat structuring method for converting liquid oils to solidified oil to reduce trans-fatty acids and saturated fat content in food formulations. In the current study, the impact of starch type and chitosan addition on the oleogelation capacity of aerogels obtained from supercritical CO2 drying technology was investigated. The starch hydrogel precursors were prepared from dent starch (27% amylose content), 55% amylose, and 72% amylose starch in the presence of 0, 0.50, and 0.75 wt% chitosan. The starch type showed a significant effect on the characteristics of resulting aerogels, where aerogels with higher content of amylose showed significantly lower shrinkage and density and higher specific surface area and macroporosity. Furthermore, chitosan addition substantially decreased the shrinkage of the aerogels, particularly those prepared with the dent starch, resulting in aerogels of lower density and higher surface area and macroporous volume. These aerogels were then powdered and employed as oil-absorbing porous materials for structuring soybean oil. Results showed that the aerogels from 55% amylose and 72% amylose starch had better oil structuring capacity compared to those from the dent starch. Furthermore, the starch aerogels supplemented with chitosan showed superior oil structuring ability than the neat starch aerogel counterparts. This work suggests that the starch type and the presence of chitosan had deep impacts on the macroporosity of the starch aerogels and their oil structuring performance.

Evaluation of the heat absorption performance of konjac glucomannan/starch aerogel

Abstract Polysaccharide-based aerogels show great potential in heat absorption, but it lacks comprehensive evaluation system for their endothermic properties. To fully assess their endothermic properties, konjac glucomannan (KGM)/starch aerogel was used and its heat absorption performance (HAP) was investigated. It was found that the heat absorption ability of the samples was attributed to thermal collapse of the samples at high temperature. The composition, structure, size and mass of aerogels would have effect on their HAP. The cellulose acetate (CA) aerogel showed better HAP than KGM/starch aerogel with the same volume. However, the performance of KGM/starch aerogel excelled CA under the same mass. These results were in accordance with the results obtained by thermal conductivity analyzer, which indicated the potential of the system to evaluate the HAP of the aerogels comprehensively.

Cassava starch-derived aerogels as biodegradable packaging materials

Biodegradable and natural materials can provide transformational solutions to environmental issues, particularly those associated with ubiquitous fossil-resources-derived conventional polymers like polyolefin thermoplastics and polystyrene foam as packaging materials. Herein, a facile approach is presented for preparing biodegradable and biocompatible lightweight structural scaffolds as an alternative to conventional plastic-based packaging materials. A variable dosage of polyvinyl alcohol (PVA) is used along with cassava starch to govern the structural integrity, mechanical properties, and porosity of resultant aerogels. The incorporation of PVA as a strengthening precursor improved the compressive modulus of starch aerogel from 2.0 to 18.2 MPa. Hydrogen-based interactions between the starch and PVA components, as revealed by infrared spectroscopic and differential scanning calorimetric measurements, extended the structural integrity. The high and regulated porosity of these aerogels furnished significantly low density (0.13–0.21 mg mm−3). A 98.5% of the starch-PVA aerogel is converted to CO2 by the microbial consortia within 23 days, signifying excellent biodegradability of these aerogels. Moreover, cassava starch-PVA aerogel is demonstrated as alternative packing material to conventional non-biodegradable black plastic bags for growing, transporting, and transplanting young plants. The improved thermal stability (<270 °C), low density, good compressive modulus (2.0–18.2 MPa), and excellent biodegradability reveal the potential of starch-based aerogels as excellent alternatives to conventional polyolefin thermoplastics and polymer-foam-based packaging materials.

Divalent metal ion removal from simulated water using sustainable starch aerogels: Effect of crosslinking agent concentration and sorption conditions

This paper evaluates corn starch aerogels, studying different crosslinking agent (trisodium citrate) concentrations (1:1, 1:1.5, and 1:2) and sorption conditions (contact time, adsorbent weight, and initial concentration) regarding the potentially toxic elements (PTEs) [Cd(II) or Zn(II)] adsorption of the aqueous systems. Besides, other properties of aerogels, such as structural properties, specific surface area, and mechanical performance, were evaluated. For adsorption results, better values were observed in adsorption capacity and efficiency for the initial concentration of 100 ppm. In addition, an adsorption time of 12 h and an adsorbent weight of 3.0 g obtained better results due to the possible balance in this time and the high specific surface area available for Cd(II) adsorption. As for the type of adsorbent, the Aero 1:1.5 sample (intermediate crosslinking agent concentration) obtained better results, possibly due to the high porosity, smaller pore sizes, high pore density, and high specific surface area (198 m2·g−1). In addition, hydroxyl groups in the starch aerogel removed Cd(II) ions with 30 % adsorption efficiency. Lastly, Aero 1:1.5 obtained a high mechanical strength at compression and a satisfactory compressive modulus. In contrast, starch aerogels did not absorb the Zn(II) ion.

Role of supercritical CO2 impregnation variables on β-carotene loading into corn starch aerogel particles

β-carotene is a natural dye with antioxidant and provitamin A activities, which has essential roles in human health. However, its direct use in food products is unviable since it is susceptible to oxidation, easily isomerization under light, heat or acids, and has low water solubility and oral bioavailability. To address this issue, this work reports, for the first time, the impregnation of β-carotene into corn starch aerogels using supercritical carbon dioxide (sc-CO2). The aerogel particles were produced by the emulsion-gelation method, dried by sc-CO2 and loaded with β-carotene by sc-CO2 impregnation. The impacts of pressure (15 and 30 MPa), temperature (40 and 60 °C), average depressurization rate (0.25–2.61 MPa/min), and cycles (1−4) were investigated on loading. Excepting depressurization rate, all variables played fundamental roles in loading, reaching a maximum of 0.96 mg β-carotene/g aerogel (30 MPa, 40 °C, 0.40 MPa/min, four cycles).

Developing dual nano/macroporous starch bioaerogels via emulsion templating and supercritical carbon dioxide drying

In this study, emulsified oil droplets were employed as a temporary porogen to obtain dual nano/macroporous starch aerogels by supercritical carbon dioxide (SC-CO2) drying. This method took advantage of the solubility of the oil droplet porogens in acetone, and the insolubility of corn starch in this solvent, so this process could be integrated into the typical aerogel processing method. The effect of porogen content and starch concentration on physical and mechanical properties and the internal morphology of the obtained aerogels were studied. While the neat starch aerogel showed a compact structure in macroscale size with interconnected nanopores, the sacrificing oil droplet porogens induced macropores in the emulsion-templated aerogels. Furthermore, the nanoporous structures of starch aerogels were also well-preserved in which the macropores were surrounded by fine and interconnected nanofibrous networks. It resulted in aerogels that exhibited internal morphology in two scales (macropores and nanopores) with a high surface area (156–190 m2/g).

A carbonized carbon dot-modified starch aerogel for efficient solar-powered water evaporation

A new low-cost and eco-friendly solar evaporator made of a carbonized carbon dot-modified starch aerogel (C-CDSA) with a high solar energy conversion efficiency and excellent stability and durability was developed for solar-powered water evaporation.

Effect of Crosslinking Agents on the Physicochemical and Digestive Properties of Corn Starch Aerogel

AbstractIn this study, sodium trimetaphosphate, adipic acid, sodium hexametaphosphate, and epichlorohydrin (EPI) are used to investigate the effect of the crosslinking reaction on the physicochemical properties and in vitro digestibility of corn starch aerogel (CSA). Gelatinization destroys the morphology of the corn starch granules, and the crosslinking reaction which is performed in the gelatinization stage considerably alters the structure of the gel. The aerogel prepared by adding 0.5% EPI shows the highest Brunauer–Emmett–Teller surface area among the crosslinked starch aerogels. Corn starch xerogels and aerogels all have porous network structures which may be related to the high amylose structure of corn starch. Gelatinization and crosslinking agents disrupt the short‐range molecular order of corn starch, and the crosslinked CSA has relatively lower crystallinity and higher swelling power and solubility than the control. After crosslinking, rapidly digestible starch and resistant starch content of CSAs increase, while slowly digestible starch decreases slightly. Thus, the crosslinked CSA may be used for encapsulation with low digestibility.

Synthesis, Characterization, Speciation, and Biological Studies on Metal Chelates of Carbohydrates with Molecular Docking Investigation

AbstractThe role of starch aerogel (St‐AG) and carboxymethyl cellulose (CMC) as biolgical active compounds, when they subjected for complexation with metal ions, is assessed in this work. The complexation is carried out with palladium(II) and copper(II) ions, in solid state. Different tools of analysis are carried out to characterize and elucidate the structures of these complexes, namely: elemental analysis, IR, thermal analysis, magnetic measurement and molar conductance techniques. All synthesized complexes are formed with 1:2 (metal:ligand) stoichiometry except the case of aerogel starch 1:1 (Pd:starch). All isolated complexes show a satisfactory cytotoxic effect results against colon cancer cell lines HCT11. Additionally, these complexes are screened for their antibacterial activities against two types of Gram positive and negative bacteria. Molecular docking investigation confirmed the cytotoxicity and antibacterial results. Proton–ligands association constants and their complex formation constants with some bivalent metal ions, using potentiometric method show that the complexes formed in solution have a stoichiometry of 1:1 [metal:ligand]. The effects of metal ion, ionic radius, electronegativity and nature of ligand on the formation constants are discussed. The formation constants of the complexes with 3D transition metals followed the order Mn2+ &lt; Co2+ &lt; Ni2+ &lt; Cu2+ &gt; Zn2+.

Stability Studies of Starch Aerogel Formulations for Biomedical Applications.

Starch aerogels are attractive materials for biomedical applications because of their low density and high open porosity coupled with high surface areas. However, the lack of macropores in conventionally manufactured polysaccharide aerogels is a limitation to their use as scaffolds for regenerative medicine. Moreover, the stability under storage of polysaccharide aerogels is critical for biomedical purposes and scarcely studied so far. In this work, the induction of a new macropore population (1-2 μm) well integrated into the starch aerogel backbone was successfully achieved by the incorporation of zein as a porogen. The obtained dual-porous aerogels were evaluated in terms of composition as well as morphological, textural, and mechanical properties. Stability of aerogels upon storage mimicking the zone II (25 °C, 65% relative humidity) according to the International Council for Harmonization guideline of climatic conditions was checked after 1 and 3 months from morphological, physicochemical, and mechanical perspectives. Zein incorporation induced remarkable changes in the mechanical performance of the end aerogel products and showed a preventive effect on the morphological changes during the storage period.

Mesoporous starch aerogels production as drug delivery matrices: synthesis optimization, ibuprofen loading, and release property.

The aim of this work was to prepare biodegradable starch aerogels as drug carriers. The effective parameters in the synthesis and the optimal values of these parameters were determined using Minitab experimental design software. Ibuprofen was selected as a model drug for the dissolution study and loaded into optimized aerogel during the last solvent exchange step. The Fourier Transform Infrared Spectroscopy (FTIR) analysis showed that ibuprofen has been successfully loaded into the aerogel matrix without any effect on the aerogel nature. The drug loading was calculated to be 29%. The isotherm of ibuprofen adsorption into aerogels matrices followed from the Freundlich isotherm. The in vitro release tests of crystalline ibuprofen and ibuprofen-loaded potato starch aerogel were investigated with simulated gastric and intestinal fluids in USP 2 apparatus. It was shown that the dissolution rate of ibuprofen could be dramatically changed. Also, an improvement in the dissolution rate of ibuprofen was achieved by performing the dissolution test first in the gastric medium for 120 min and then in the intestinal medium for up to 270 min. A higher release rate (100%) was observed at the end of the in vitro experiment.

Supercritical CO2 Impregnation of Alpha-tocopherol in Different Aerogels

a-tocopherol (TOC), a poorly water-soluble vitamin, was impregnated using supercritical carbon dioxide in two different porous supports: an inorganic one (silica aerogel, SA) and a biopolymer one (maize starch aerogel, MSA). The composite systems can be used for the attainment of novel delivery systems with a rapid or controlled vitamin dissolution rate. TOC impregnation experiments on both the supports were carried out at a pressure of 15 MPa and a temperature of 60 °C. Impregnation equilibrium data were measured and represented as isotherms, whereas impregnation kinetic data were obtained by determining the TOC uptake on the two supports at various times. The TOC/aerogel composites were characterized by FESEM analysis and specific surface area determination. To study the properties of the adsorbed aerogels, as vitamin delivery systems, in vitro dissolution tests were performed. The dissolution rates of TOC charged in silica aerogel or maize starch aerogel using phosphate buffered saline solution (PBS) were compared with the one of the unprocessed vitamin.

Production of starch aerogel in form of monoliths and microparticles

Pea and amylomaize starches were used to produce aerogel in form of monoliths and microparticles. The formation of starch gel was investigated, and we showed that each starch needed a different pasting temperature for its complete dissolution. The gelation kinetics was investigated with oscillatory rheometry for both systems as a function of the starch concentration. The gelation and retrogradation temperature of the starch gel were varied and its impact on the final aerogel evaluated. The emulsion gelation was carried out batch wise in a stirred vessel with different impeller geometries, concentrations of surfactant (Span80 and PGPR) and stirring rates. A particle size prediction approach based on idealized flow (Couette, 2D hyperbolic and turbulent) during the emulsification was proposed. A semi-continuous set-up for the emulsion gelation was developed in which the emulsification occurs in a single pass through a colloid mill and the gelation is triggered in-line with a counter-current heat exchanger.Graphical abstract.

Supercritical CO2 adsorption of non-steroidal anti-inflammatory drugs into biopolymer aerogels

Supercritical carbon dioxide adsorption was applied to incorporate three non-steroidal anti-inflammatory drugs (NSAIDs), namely nimesulide (NIM), ketoprofen (KET) and diclofenac sodium (DIC), into maize starch aerogel (MSA) and calcium alginate aerogel (CAA). The obtained composites can be used to develop tablets with a fast or controlled release of the active principle, depending on the chosen aerogel. Adsorption kinetics and isotherms were determined at 18 MPa and 40 and 60 °C to study the effect of temperature. Adsorption kinetics demonstrated for all compounds that drug loadings were higher using CAA as a support than MSA. Indeed, the maximum loadings were obtained at 60 °C and were equal to 0.13, 1.64 and 3.43 mmoldrug/gCAA for NIM, KET and DIC, respectively. The produced composite systems were characterized by various techniques, such as scanning electron microscopy, differential scanning calorimetry, X-ray microanalysis, FT-IR and UV–vis spectroscopy. Dissolution tests revealed that the adsorption into MSA allowed a faster release of the NSAIDs than pure crystalline drugs, whereas CAA promoted a controlled release of the NSAIDs. For example, the dissolution rate of NIM, if compared with the one of the unprocessed drug, is 1.5 times faster when adsorbed into MSA and 4.6 times slower if adsorbed into CAA. Moreover, Peppas mathematical model was applied to identify the dominant factor in the drug release behavior.

Porous Starch Materials via Supercritical- and Freeze-Drying.

The production of porous materials based on starch has been explored with supercritical drying—yielding aerogel—and freeze-drying. The two drying procedures were applied on the same gelling solution of amylomaize starch pasted at 140 °C and for two concentrations (5 and 10 wt.%). After gelation and retrogradation, water from the samples to be supercritically dried was exchanged to ethanol. The resulting starch aerogel presented high specific surface area (197 m2/g). Freeze-drying was assessed by investigating the effect of the gelation, retrogradation, freezing temperature, and sublimation pressure. The resulting starch materials were macroporous, with limited specific surface area and limited mechanical integrity. Cohesive open cell foam with pore size of ~20 µm was produced by quenching the hot starch melt in liquid nitrogen. The highest specific surface area obtained with freeze-drying was 7.7 m2/g for the hot starch melt frozen at −20 °C.

Supercritical Adsorption of Quercetin on Aerogels for Active Packaging Applications

Quercetin, a flavonoid with outstanding antioxidant and antimicrobial properties, was adsorbed onto maize starch aerogel (MSA) and calcium alginate aerogel (CAA) through supercritical carbon dioxid...

Life cycle assessment of supercritical impregnation: Starch aerogel + α-tocopherol tablets

The environmental impacts of starch aerogel (SA) loaded with vitamin E (α-tocopherol, TOC) using supercritical carbon dioxide impregnation were evaluated, following a Life Cycle Assessment (LCA) approach. All the emissions to air, water and soil were reported to a 120 mg SA tablet containing the daily therapeutic dose of TOC (15 mg). The life cycle inventory was built using primary data and the LCA analysis was conducted using SimaPro 8.5.2 software. The performed analysis showed that the stages most affecting the environmental categories under study are the agricultural stages, the supercritical drying for the attainment of the aerogel and the supercritical impregnation. Solutions aimed at minimizing the impacts of these steps were proposed.