Structural Modifications Research Articles

Comparative effectiveness of Nitro dihydrocapsaicin, new synthetic derivative capsaicinoid, and capsaicin in alleviating oxidative stress and inflammation on lipopolysaccharide-stimulated corneal epithelial cells

Loss of tear homeostasis, characterized by hyperosmolarity of the ocular surface, induces cell damage through inflammation and oxidation. Transient receptor potential vanilloid 1 (TRPV1), a sensor for osmotic changes, plays a crucial role as a calcium ion channel in the pathogenesis of hypertonic-related eye diseases. Capsaicin (CAP), a potent phytochemical, alleviates inflammation during oxidative stress events by activating TRPV1. However, the pharmacological use of CAP for eye treatment is limited by its pungency. Nitro dihydrocapsaicin (NDHC) was synthesized with aromatic ring modification of CAP structure to overcome the pungent effect. We compared the molecular features of NDHC and CAP, along with their biological activities in human corneal epithelial (HCE) cells, focusing on antioxidant and anti-inflammatory activities. The results demonstrated that NDHC maintained cell viability, cell shape, and exhibited lower cytotoxicity compared to CAP-treated cells. Moreover, NDHC prevented oxidative stress and inflammation in HCE cells following lipopolysaccharide (LPS) administration. These findings underscore the beneficial effect of NDHC in alleviating ocular surface inflammation, suggesting that NDHC may serve as an alternative anti-inflammatory agent targeting TRPV1 for improving hyperosmotic stress-induced ocular surface damage.

Enhancing Infrared Drying of Red Dragon Fruit by Novel and Innovative Thermoultrasound and Microwave-Mediated Freeze-Thaw Pretreatments

This study investigated the effectiveness of novel and innovative pretreatments (NIP) using thermoultrasound and microwave-mediated freeze-thaw (TSFT, MWFT) for improving the mid-infrared drying of dragon fruit, as compared with recent pretreatment methods using cold plasma (CP), ultrasound (US), edible coating (EC), microwave and infrared blanching (MWB, IRB). Except for EC, all selected pretreatment methods induced ultrastructural changes, resulting in accelerated moisture removal and reduced drying time. In addition, all the pretreatments also induced modifications in colour, structure, and texture, with NIP demonstrating superior outcomes for colour, rehydration, shrinkage, and hardness properties. Blanching pretreatments (MWB and IRB) improved phytochemical and antioxidant properties, including total phenolics, betacyanin, betaxanthin, CUPRAC, hydroxyl radical scavenging, and ABTS, except for ascorbic acid, which was better preserved by TSFT. The study underscores the time-saving and quality enhancement advantage of NIP, over other recent methods for improving mid-infrared drying.

In-situ construction of epitaxial phase for boosting zinc nucleation on three-dimensional interface

Interface modification of zinc (Zn) metal anode with conductive three-dimensional (3D) structure is widely utilized in zinc ion batteries. However, the uniformity of zinc nucleation on surface microstructure is rarely investigated which exacerbates the tip effect and raises unstable risk. Herein, a strategy via the initial copper (Cu) alloying and following sulfurization treatment is reported to accomplish boosted uniform nucleation of zinc on the modified layer with dense microstructures. This epitaxial sulfide phase not only improves the wetting area to revitalize the microstructural surface, but also forms a bifunctional zincophilic Cu2S/CuZn alloy interface layer, which combines the merits of guided local ions diffusion and improved zinc nucleation environment. As a result, a homogeneous growth of zinc on the 3D structural substrate can be realized, and cycling stability of the achieved Cu2S/CuZn electrode with a practical capacity of 1 ​mAh cm−2 under 1 ​mA ​cm−2 or amplified current density of 10 ​mA ​cm−2 is significantly enhanced. This work provides an epitaxial strategy in constructing a bifunctional zincophilic interface layer for boosting zinc nucleation, and offers a new perspective on the modification of 3D surface structure for stabilization of zinc anode.

HPLC with chiral stationary phase for separation and kinetics study of aspartic acid epimerization in Peroxiredoxin 2 active site peptide

Amino acid epimerization, a process of converting L-amino acids to D-amino acids, will lead to modification in the protein structure and, subsequently, its biological function. This modification causes no change in protein m/z and may be overlooked during protein analysis. Aspartic Acid Epimerization (AAE) is faster than other amino acids and could be accelerated by free radicals and peroxides. In this work, a novel and site-specific HPLC method using a chiral stationary phase for determining the AAE in the active site model peptide (AP) of Peroxiredoxin 2 has been developed and validated. The developed method showed good linearity (1 – 200 μg/mL) and recoveries of the limit of quantification (LOQ), low, medium, and high concentrations were between 85% and 115%. The Kinetics of AAE in AP were studied using the developed method, and the results showed that when ascorbic acid and Cu2+ coexisted, the AP epimerized rapidly. The AAE extent increased with time and was positively correlated with hydrogen peroxide generation.

Nanoprecipitation induced giant magnetostriction: A time-resolved small-angle neutron scattering study of the vacancy-assisted kinetics

Solid-state precipitation is an effective strategy for tuning the mechanical and functional properties of advanced alloys. Structure design and modification necessitate good knowledge of the kinetic evolution of precipitates during fabrication, which is strongly correlated with defect concentration. For Fe-Ga alloys, giant magnetostriction can be induced by the precipitation of the nanoscale tetragonal L60 phase. By introducing quenched-in vacancies, we significantly enhance the magnetostriction of the aged Fe81Ga19 polycrystalline alloys to ∼305 ppm, which is close to the level of single crystals. Although vacancies were found to facilitate the generation of the L60 phase, their impact on the precipitation mechanism and kinetics has yet to be revealed. This study combined transmission electron microscopy (TEM) and time-resolved small-angle neutron scattering (SANS) to investigate the precipitation of the L60 phase during the isothermal aging at 350 and 400 °C, respectively. The evolution of L60 nanophase in morphology and number density in as-cast (AC) and liquid nitrogen quenched (LN) Fe81Ga19 alloys with aging time were quantitatively compared. Interestingly, the nucleation of the L60 phase proceeds progressively in AC while suddenly in LN specimens, indicating the homogenous to heterogeneous mechanism switching induced by concentrated vacancies. Moreover, excess vacancies can change the shape of nanoprecipitates and significantly accelerate the growth and coarsening kinetics. The magnetostrictive coefficient is optimized when the size (long-axis) of L60 precipitates lies between 100–110 Å with a number density between 3.2–4.3 × 10–7 Å–3. Insight from this study validates the feasibility of achieving high magnetoelastic properties through precise manipulation of the nanostructure.

Magnetic/electric synergy Co@CN/CNTs absorber toward high efficiency electromagnetic waves absorption

Metal-organic framework (MOF) has gained widespread attention as promising electromagnetic waves (EMWs) absorbent due to its 3D structure, porosity and easier modification. However, the structural instability and impedance mismatch presented a serious challenge in meeting the ultra-strong and ultra-broad absorption requirement for EMWs. Therefore, a facile strategy has been applied to prepare carbon nanotubes modified nitrogen-doped carbon encapsulated Co (Co@CN/CNTs) composites by regulating the mass ratio of Co-ZIF67 and melamine under high-temperature pyrolysis. The in-situ synthesis of CNTs and doping of nitrogen-atoms optimized the impedance matching of Co@CN/CNTs composites. The 3D heterostructure, porosity, surface defects and conductive network enhanced EMWs absorption ability. The ultra-strong reflection loss (RL) for Co@CN/CNTs-1:1 sample of −112.14 dB was reached with only 1.3 mm match thickness and corresponding ultra-broad effective absorption bandwidth (EAB) was up to 8.2 GHz. This research could be expected to provide a novel scheme for design and preparation of MOFs derived EMWs absorption materials.

Shaping the Future of the Neurotransmitter Sensor: Tailored CdS Nanostructures for State-of-the-Art Self-Powered Photoelectrochemical Devices.

Semiconductor-based photoelectrochemical (PEC) test protocols offer a viable solution for developing efficient individual health monitoring by converting light and chemical energy into electrical signals. However, slow reaction kinetics and electron-hole complexation at the interface limit their practical application. Here, we reported a triple-engineered CdS nanohierarchical structures (CdS NHs) modification scheme including morphology, defective states, and heterogeneous structure to achieve precise monitoring of the neurotransmitter dopamine (DA) in plasma and noninvasive body fluids. By precisely manipulating the Cd-S precursor, we achieved precise control over ternary CdS NHs and obtained well-defined layered self-assembled CdS NHs through a surface carbon treatment. The integration of defect states and the thin carbon layer effectively established carrier directional transfer pathways, thereby enhancing interface reaction sites and improving the conversion efficiency. The CdS NHs microelectrode fabricated demonstrated a remarkable negative response toward DA, thereby enabling the development of a miniature self-powered PEC device for precise quantification in human saliva. Additionally, the utilization of density functional theory calculations elucidated the structural characteristics of DA and the defect state of CdS, thus establishing crucial theoretical groundwork for optimizing the polymerization process of DA. The present study offers a potential engineering approach for developing high energy conversion efficiency PEC semiconductors as well as proposing a novel concept for designing sensitive testing strategies.

Studies on Comprehensive Total Synthesis of Natural and Pseudo-Natural Products for Drug Discovery.

Natural products are important for the development of pharmaceuticals and agrochemicals; thus, their synthesis and medicinal chemistry research is critical. Developing a total synthesis pathway for natural products confirms their structure and provides the opportunity to modify the structure in a targeted manner. A simple modification of a single oxidation step can increase the biological activity, or the complexity of the molecule can alter the property. Herein, we discuss the asymmetric total synthesis of dihydroisocoumarin-type natural products, the creation of novel antibacterial compounds through partial structural modification, and the development of antioxidants with high activity and low toxicity through dimerization strategies.

A laboratory study on the durability of limestone wastes in harsh environments for their suitability as aggregate in concrete

One of the critical environmental issues in the Chegeni area (Lorestan Province, western Iran) is the production of a large volume of limestone wastes during the quarrying operations. Releasing limestone wastes in the areas neighboring the quarries has caused visual damage to the environment, and adverse effects on the quality of the soil, running water, and groundwater used for agricultural and drinking water purposes. One solution to this issue can be recycling limestone wastes to produce building materials. In the present study, a comprehensive laboratory program is planned for the durability evaluation of the limestone wastes under harsh environments for their suitability as aggregate in concrete. For this purpose, five aging tests, including freeze-thawing (F-T), salt crystallization (SC), acid attack (AA), wetting-drying (WD), and heating-cooling (HC), were conducted on the limestone sample up to 60 cycles. After every 10 cycles, the physico-mechanical characteristics of the sample, including porosity (n), Brazilian tensile strength (BTS), point load index (PLI), and P-wave velocity (Vp) were determined. Moreover, the pores structure modification of the sample subjected to aging tests was examined through scanning electron microscopy (SEM). Data analyses revealed that the sample is highly vulnerable to the AA and SC processes but is durable against FT, WD, and HC actions. These results were in good agreement with the SEM data such that the sample exposed to AA and SC underwent more changes in their pore structure compared to FT, WD, and HC. Among the physico-mechanical characteristics, the Vp and PLI had the highest and the lowest accuracy, respectively, in the durability evaluation of the sample exposed to aging tests. Based on the data analysis, limestone wastes can be used as aggregate in concrete in environments with the possibility of FT, WD, and HC. However, this type of concrete is not suitable for conditions with occurrences of the AA and SC. Finally, in addition to reducing the environmentally harmful impacts of the study area, using limestone wastes as aggregate in the construction of concrete can also be a practical solution for sustainable development from an economic viewpoint. The results of the present study can be used for assessing limestone wastes produced in other areas of Iran and the world.

Carbon nanofibers supported sorbents with enhanced performance via microwave-assisted in-situ structural modifications for H2S removal

The construction of sorbent with excellent structure and highly dispersed active components is vital to improving its desulfurization activity. Herein, the Fe nanoparticles/carbon nanofibers (Fe/CNFs) desulfurization sorbents were fabricated via electrospinning, template method and microwave carbonization. The structure of sorbents was successfully regulated with the adjustments of Fe content and the types of sacrificial phases. It was found that the Fe content impacted strongly on both structural and desulfurization performance of the sorbents. The sorbents with various Fe contents showed a trend of first increasing and then decreasing with the increased Fe content in breakthrough sulfur capacity. Among the various samples, the sample with the highest sulfur content was 7.21 g S/100 g sorbent. Furthermore, the Fe/CNFs sorbents were optimized via soft and hard template methods, by taking polymethyl methacrylate (PMMA) and SiO2 nanospheres as sacrificial phases. Desulfurization tests implied that the PMMA and SiO2 modified sorbents involved sulfur capacity of 13.76 and 14.18 g S/100 g sorbent, respectively. According to the characterizations, the modified sorbents were imparted with micro- and open-type macro-porous structure, respectively, upon which, the active components were uniformly dispersed and exposed. The excellent performance of sorbent could be attributed to the synergistic effect of porous structure and widely distributed Fe nanoparticles on CNFs. This work highlights new strategy for the synthesis of desulfurization sorbent.

Evaluating the impact of pulsed light treatment on microbial and enzyme inactivation and quality attributes in fresh‐cut watermelon

AbstractThis study investigated the impact of pulsed light (PL) applied at a fluence of 4–12 J cm−2 (complying with U.S. Food and Drug Administration standards) on fresh‐cut watermelon, focusing on its efficacy in inactivating various food‐borne pathogenic gram‐positive (Escherichia coli and Staphylococcus aureus) and gram‐negative (Listeria monocytogenes and Salmonella) bacteria. The inactivation data were used to fit the log‐linear and Weibull kinetic models. Additionally, the impact of PL on physicochemical properties, lycopene content, total phenolic content, antioxidant activity, and pectin methylesterase (PME) residual activity (RA) was studied. The results demonstrated that the inactivation rate increases with the increase in fluence. Salmonella was most sensitive to PL, resulting in a reduction of 2.55 ± 0.08 log CFU g−1 and a higher kmax, whereas S. aureus was most resistant, with a reduction of 1.87 ± 0.24 log CFU g−1 and a lower kmax. The Weibull model was the best to predict the inactivation kinetics based on standard statistics and information theory criteria. For all assayed food‐borne pathogens, the inactivation curve showed non‐linearity with upward concavity except for L. monocytogenes, which followed a concave downward curve (β >1). Results showed that PL was effective in the retention of color, firmness, pH levels, total soluble solids, and titratable acidity, and also had a positive effect on enhancing the levels of essential components such as lycopene, total phenolic compounds, and antioxidant activity. Additionally, the PME RA significantly decreased with an increase in fluence due to structural modification. Therefore, PL can be explored to enhance fresh‐cut watermelon's safety and quality attributes.Practical ApplicationsThe implementation of this research holds significant potential for practical benefits in the fresh‐cut fruit industry. The findings could revolutionize processing practices, ensuring enhanced microbial safety, enzyme inactivation, and an extended shelf‐life of fresh‐cut watermelon. The study strongly contributes to preserving the desirable texture, color, and overall quality of the product, enhancing the retention of lycopene and other valuable antioxidants by standardizing the pulsed light treatment parameters while adhering to U.S. Food and Drug Administration standards for food application. Moreover, this research will scientifically contribute to addressing the critical challenges of foodborne outbreaks in the fresh‐cut fruit sector while providing consumers with a healthy, convenient food choice.

Structural modification of graphene material by silicon mono-doping and co-doping with heteroatoms as sensors for methyl tert-butyl ether (MTBE) as a fuel additive: Insight from DFT and MD simulation

Due to the association of Methyl tert-butyl ether (MTBE) with groundwater contamination and environmental concerns, fuel additive, as well as its recognized health hazards, including respiratory and central nervous system effects upon exposure, the implementation of mitigating measures becomes imperative on a global scale, particularly through the utilization of nano-oriented materials. Hence, to account for the sensitivity, detection, and adsorption of methyl tert-butyl ether (MTBE) pollutant, this research attempts to investigate the potentials of silicon-doped graphene (Si@GP), engineered along with boron, nitrogen, and phosphorous atoms by employing density functional at the ωB97XD/def2vsp level of theory. Interestingly, results from several quantum descriptors were analyzed for comprehensive knowledge of the interaction between the adsorption complexes. The examined systems (MTBE-Si@GP, MTBE-SiB-GP, MTBE-SiN-GP, and MTBE-SiP-GP) produced Fermi energy values of 0.4531 eV, 0.4531 eV, 0.5274 eV, and 0.3936 eV respectively, providing valuable insights into their electronic structure and sensitivity to MTBE. Subsequent calculations revealed that MTBE-SiP-GP had a work function of 0.3936 eV, making it a superior surface for sensing MTBE compared to other surfaces considered. The adsorption energies for MTBE-Si@GP, MTBE-SiB-GP, MTBE-SiN-GP, and MTBE-SiP-GP were 8.004 eV, 7.159 eV, 7.785 eV, and 5.027 eV, respectively. Despite their physisorption prowess, MTBE-SiP-GP was highlighted as the preferable absorbent at the BSSE level. Consequently, the overall analysis identified silicon and phosphorous doped system (SiP-GP) as a favorable adsorbent for selectivity, detection, and adsorption of MTBE liquified gas.

Unveiling the ability of protic and aprotic ionic liquids to dissolve and modify Kraft lignin

Lignin, a renewable macromolecule abundant in lignocellulosic biomass, holds significant promise as a renewable source for producing biofuels, biomaterials, and fine chemicals, offering a potential avenue to reduce dependence on petroleum-derived products. However, the lignin complex structure poses challenges for its effective utilization, often requiring some special treatments. In recent decades, ionic liquids (ILs) have been pointed out as promising candidates for lignin processing due to their appealing properties, which include low vapor pressure/flammability, high chemical and thermal stability, and efficacy as lignin solvents. ILs may be categorized as protic (PILs) or aprotic ionic liquids (AILs), and these two classes offer distinct advantages. PILs are readily synthesized by mixing an acid and a base in stoichiometric proportions, forming a mixture containing neutral species that remain in equilibrium with cations and anions. In contrast, AILs present cations with enduring positive charges and are not in equilibrium with their precursors as the PILs, though AILs are frequently more expensive and challenging to produce. Within the biorefinery context, the ability to dissolve Kraft lignin is pivotal for developing new strategies and technologies. Moreover, chemical transformations may occur during lignin dissolution in IL solutions. In this study, the solubility of Kraft lignin was evaluated in four neat imidazolium-based AILs, five neat pyrrolidinium-based PILs, and in aqueous solutions of these ILs, at 313.2 K. The highest solubility value ((77.71 ± 1.03) wt%) was observed for pyrrolidinium octanoate (PIL), while 1-butyl-3-methylimidazolium methyl sulfate exhibited the highest solubility ((73.93 ± 1.27) wt%) among the studied AILs. Whenever possible, the solubilities measured in the present work were critically compared with data available in the literature. Finally, lignin recovered from the IL solutions was analyzed by Gel Permeation Chromatography (GPC), Fourier Transform Infrared (FTIR), and Nuclear Magnetic Resonance (NMR) spectroscopy to assess the solvent ability to induce structural modifications in this macromolecule. The analysis revealed that ILs effectively cleaved β-O-4 linkages in lignin molecules, and concurrent condensation reactions might increase the precipitated lignin molecular weight.

Selective Activation of Methane on Hydroxyapatite Surfaces: Insights from Machine Learning and Density Functional Theory

The electrocatalytic conversion of methane has attracted considerable attention owing to its ability to operate under mild conditions, thereby avoiding peroxidation. Recently, hydroxyapatite (HAP), an environmental-friendly and cost-effective electrocatalyst, was found to have high catalytic selectivity for the methane activation to produce alcohols. However, the overall activation mechanism still remains elusive and thus limits further improvement of the catalytic performance. In this study, we employed machine learning-assisted molecular dynamics simulations to analyze the structural modifications in the HAP with defects during sintering. Density functional theory calculations were performed to explore the catalytic mechanism of methane on various sintered surfaces of HAP. During the sintering of HAP, the presence of H2O or O vacancies causes the migration of H2O and OH species from the bulk phase toward the surface. On the basis of our simulations, the H2O or OH migration reduces the overpotential of oxygen evolution reactions and alters the stability of intermediates. It largely impacts the selectivity of methane activation and different products can be obtained depending on the defect modes. Our mechanistic proposal then fundamentally challenges the prevailing opinion that active sites are exclusively confined to the surface of HAP. Our work may pave the way for designing and synthesizing novel electrocatalysts with enhanced performance and efficiency.

BODIPY-Based Macrostructures: A Design Strategy toward Enhancing the Efficiency of Dye-Sensitized Solar Cells.

Among the metal-free dyes, boron dipyrromethene (BODIPY) has attracted much attention in the solar cell industry due to its thermal stability and tunable electronic and photophysical properties. However, the low power conversion efficiency of dye-sensitized solar cells based on BODIPY has limited their widespread application. Accordingly, different types of structural modifications have already been proposed to improve the photophysical properties of the BODIPY dyes. In this study, we used the strategy of constructing BODIPY-based covalent macrostructures by integrating two BODIPY subunits via a π-linker in linear and cyclic configurations. To this end, various types of the π-linkers including butadiyne, phenyl, and thiophene derivatives are considered. The structural, electronic, and optical properties as well as the photovoltaic performance of BODIPY dimers are theoretically calculated within DCM solvent. The results indicate that for a given linker, the BODIPY dimers with a linear configuration show better performance as compared to their macrocyclic counterparts. The reason is the enhancement of π-conjugation length, higher light harvesting ability, and proper charge carrier separation in linearly linked BODIPYs. In the cyclic series, the dyes incorporating phenyl linkers exhibit greater power conversion efficiency of up to 9%. For the dyes with a linear configuration, the involvement of a thienyl-thiophene bridge results in lower charge recombination and enhances the efficiency by up to 15%, which are expected to be potential candidates for organic dyes applied in DSSCs.

Design, synthesis and molecular docking of 5-fluoro indole derivatives as inhibitors of PI3K/Akt signalling pathway in cervical cancer

The PI3K/Akt signalling pathway promotes variety of cellular processes and the inhibition of PI3K/Akt signalling pathway could lead to decrease in tumour growth effectively in cancer cells. AD412, an indole derivative, is a potent immunosuppressive agent which also reported as an anticancer agent through significant inhibition of PI3K/Akt signalling pathway. In this current work, we designed and synthesized the two diverse lead series of 5-fluoro indole derivatives (6a-l and 11a-l) by specific structural modifications of AD412. In total, 24 new derivatives were evaluated for their antiproliferative activity against two cervical cancer cell lines (HeLa and SiHa) and a normal cell line (HEK 293). Among them, 6e exhibited excellent antiproliferative activity against HeLa and SiHa cells with IC50 values of 9.366 and 8.475 µM respectively, as well displayed a low toxicity profile. Further, 6e inhibited the migration and invasion of HeLa cells in a dose-dependent manner by affecting the synthesis of DNA. Moreover, the Western blot analysis revealed that 6e could inhibit cervical cancer progression by downregulating the PI3K-p85 and phosphorylation of Akt in Hela cells. In vitro mechanism studies demonstrated that 6e could significantly increase apoptosis in HeLa cells by upregulating the expression of proapoptosis related protein Bax. The binding mechanism and the activity profile of 5-fluoro indole derivatives were validated by employing molecular docking studies against the active sites of Akt and PI3K enzymes. In addition, in silico ADME and pharmacokinetic parameters prediction of compound 6e resulted in good oral bioavailability. Therefore, compound 6e could be a lead compound for further development of PI3K/Akt inhibitors and anticancer agents.

PH-induced complex coacervation of Gel and Agar: Phase behavior and structural properties

In this study, we investigated the behavioral patterns of gelatin (Gel) and Agar in terms of composites and phase separation. As the pH (4.5-7.0) increased, the electrostatic interaction between the gel and the agar weakened, and a decrease in the degree of agglomeration of the microstructure was observed in the confocal laser scanning microscope (CLSM) plots. Specifically, When the ratio of Gel to Agar was 2:1 and the pH was 4.5 (pHopt), a large amount of complex coalescence appeared. The Absorption and fluorescence spectra demonstrated the impact of Agar interaction on the tertiary conformation of the Gel, while circular dichroism (CD) detected changes in its secondary structure. Furthermore, Fourier Transform Infrared Resonance spectroscopy (FTIR) demonstrated that the complexes were produced through electrostatic interactions between the -NH3+ groups of Gel and –COO- groups of Agar. The Gel-Agar coacervation process induced structural modifications, which enhanced the Gel’s thermal stability. The findings of this study are expected to be an essential contribution to the potential application of Gel-Agar coacervates for encapsulating functional ingredients.

Effect of carboxymethyl chitosan on the storage stability of rice dough during frozen storage.

In this study, we aimed to determine the effect of carboxymethyl chitosan (CMCh) and carboxymethyl cellulose sodium (CMCNa) on the quality of frozen rice dough. We used a variety of methods to conduct a thorough investigation of frozen rice dough, including nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, size exclusion high-performance liquid chromatography (SE-HPLC), X-ray diffraction (X-RD), differential scanning calorimetry (DSC), and rapid visco analyzer (RVA). Our findings showed that frozen storage caused significant damage to the texture of rice dough, and this damage was reduced by the inclusion of CMCh, which led to a gradual change in the orderly structure of proteins. The degree of cross-linking between CMCh-B (DS:1; 0.5 %, 1 %, and 1.5 %) and the large protein polymer was significantly higher than that between CMCh-A (DS:0.8; 0.5 %, 1 %, and 1.5 %) and CMCNa (DS:1; 1 %), which decreased the ability of bound water to become free water. This resulted in the increase of tan δ, which effectively delayed the structural transformation of frozen rice dough. Furthermore, the introduction of CMCh delayed the immediate order of starch and crystal structure modifications, altering the thermal properties and pasting qualities of the frozen rice dough. Therefore, 1.5 % CMCh-B showed the best protective effect on frozen rice dough.

Enzyme-catalyzed transesterification of galactomannan extracted from mesquite seed (Prosopis velutina) with vinyl carboxylate esters

Galactomannans (GM) are hemicellulosic polysaccharides composed of D-mannopyranose chains linked by β (1→4) glycosidic linkages with branches of D-galactopyranose linked by α (1→6) linkages. This polysaccharide is recognized for its hydrophilic character, as it is rich in hydroxyl groups (-OH). This chemical characteristic, combined with the absence of ionic charges, enables structural modifications such as transesterification of the fatty acid chains (FA), which provides a strategy for obtaining amphiphilic structures. The enzyme-catalyzed syntheses were carried out in DMSO with GM decanoate (GMD) and GM palmitate (GMP) at different molar ratios (0.5 and 1.0) and the resulting structures were evaluated with infrared spectroscopy (FTIR), solid-state nuclear magnetic resonance (CP/MAS 13C-NMR) and differential scanning calorimetry (DSC). The FTIR spectrum confirmed the transesterification of GM with the appearance of a C=O band (1730-1750 cm-1). These results were confirmed by the signals observed at 177 and 30 ppm in the CP/MAS 13C-NMR spectrum, which corresponded to the C=O groups of the esters and the terminal -CH3 groups of the FA chains, respectively. Finally, DSC showed glass transition temperatures (Tg) in the range 43–51 °C, while the melting temperatures (Tm) of the GM esters (59 °C) were not affected by different degrees of esterification (DE) for GMD (0.37 and 0.71) and GMP (0.47 and 0.57).

Development of silanized bacterial cellulose aerogels for the incorporation of natural oils with healing properties: Copaiba (Copaifera officinalis), bourbon geranium (Pelargonium X ssp.) essential oils and buriti (Mauritia flexuosa) vegetable oil

Bacterial cellulose (BC) represents a promising biomaterial, due to its unique and versatile properties. We report, herein, on purposely-designed structural modifications of BC that enhance its application as a wound dressing material. Chemical modification of the functional groups of BC was performed initially to introduce a hydrophobic/oleophilic character to its surface. Specifically, silanization was carried out in an aqueous medium using methyltrimethoxisilane (MTMS) as the silanizing agent, and aerogels were subsequently prepared by freeze-drying. The BC-MTMS aerogel obtained displayed a highly porous (99 %) and lightweight structure with an oil absorption capacity of up to 52 times its dry weight. The XRD pattern indicated that the characteristic crystallographic planes of the native BC were maintained after the silanization process. Thermal analysis showed that the thermal stability of the BC-MTMS aerogel increased, as compared to the pure BC aerogel (pBC). Moreover, the BC-MTMS aerogel was not cytotoxic to fibroblasts and keratinocytes. In the second step of the study, the incorporation of natural oils into the aerogel's matrix was found to endow antimicrobial and/or healing properties to BC-MTMS. Bourbon geranium (Pelargonium X ssp.) essential oil (GEO) was the only oil that exhibited antimicrobial activity against the tested microorganisms, whereas buriti (Mauritia flexuosa) vegetable oil (BVO) was non-cytotoxic to the cells. This study demonstrates that the characteristics of the BC structure can be modified, while preserving its intrinsic features, offering new possibilities for the development of BC-derived materials for specific applications in the biomedical field.