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The aim of the present work was to modify the exuded gum of Sterculia striata tree by an amination reaction. The viscosity and zero potential of the chicha gum varied as a function of pH. The modification was confirmed by X-ray diffraction (XRD), infrared spectroscopy (FTIR), size exclusion chromatography (SEC), zeta potential, thermogravimetric analysis (TG), and differential scanning calorimetry (DSC). Furthermore, the chemical modification changed the molar mass and surface charge of the chicha gum. In addition, the gums were used in tests for ex vivo mucoadhesion strength, antibacterial activity against the standard strain of Staphylococcus aureus (ATCC 25923), inhibitory activity of α-glucosidase, antioxidant capacity, and viability of Caco-2 cells. Through these tests, it was found that amination caused an increase in the mucoadhesive and inhibitory activity of chicha gum against the bacterium Staphylococcus aureus. In addition, the gums (pure and modified) showed antioxidant capacity and an inhibitory effect against the α-glucosidase enzyme and did not show cytotoxic potential.

In recent years, research has been conducted in search of alternative adhesives that are less harmful to human health and the environment. Cardanol derived from cashew nut shell liquid (CNSL) has attracted considerable attention due to its chemical and specific characteristics (antioxidant activity, flame resistance, and hydrophobicity). In this sense, this study aimed to evaluate the quality of particleboards using cardanol instead of urea-formaldehyde (UF) adhesive. Different percentages of cardanol were used (0, 20, 40, 60 and 80%) in which its physicochemical properties were evaluated. The panels were produced with particles of Pinus oocarpa and nominal density of 0.75 g/cm

In this work, a ZnO hemisphere-like structure co-doped with Er and Cr was obtained by the co-precipitation method for photocatalytic applications. The dopant’s effect on the ZnO lattice was investigated using X-ray diffraction, Raman, photoluminescence, UV-Vis and scanning electron microscopy/energy dispersive spectroscopy techniques. The photocatalytic response of the material was analyzed using methylene blue (MB) as the model pollutant under UV irradiation. The wurtzite structure of the Zn0.94Er0.02Cr0.04O compound presented distortions in the lattice due to the difference between the ionic radii of the Cr3+, Er3+ and Zn2+ cations. Oxygen vacancy defects were predominant, and the energy competition of the dopants interfered in the band gap energy of the material. In the photocatalytic test, the MB degradation rate was 42.3%. However, using optimized H2O2 concentration, the dye removal capacity reached 90.1%. Inhibitor tests showed that •OH radicals were the main species involved in MB degradation that occurred without the formation of toxic intermediates, as demonstrated in the ecotoxicity assays in Artemia salina. In short, the co-doping with Er and Cr proved to be an efficient strategy to obtain new materials for environmental remediation.

A nanocomposite hydrogel has potentially applicability in the induction of osteogenesis. The hydrogel was synthesized using 1% gelatin methacrylate (GelMA), a biodegradable and bioactive polymer containing the structure of gelatin, denatured collagen derived from the extracellular bone matrix, and 6% laponite (Lap), a synthetic phyllosilicate of nanosized particles. Initially, 0.6 g of Lap was added to deionized water, and then a solution of GelMA/Igarcure was added under stirring and UV light for crosslinking. The spectra in the Fourier-transform infrared region showed bands that indicate the interaction between gelatin and methacrylate anhydride. X-ray diffraction patterns confirmed the presence of Lap and GelMA in the hydrogel. The thermogravimetric analysis suggested an increase in the thermal stability of the hydrogel with the presence of clay mineral. Rheological analysis showed that the hydrogel had a viscosity that allowed its injectability. The hydrogel did not show acute toxicity at any of the concentrations tested according to the Artemia salina lethality test. It showed cell viability more significant than 80% in the MTT test, which makes it suitable for in vivo osteogenic induction tests. The cell differentiation test showed the differentiation of stem cells into osteogenic cells. It indicates a material with the potential for osteogenic induction and possible application in bone tissue engineering.

Given the increase in environmental pollution, especially of water, the emergence of studies that seek to develop strategies to mitigate/treat such effects have gained prominence in the world scientific community. Among the numerous adsorption processes, those made from biochar production stand out. This study analyzed the adsorption properties of the blue methylene model dye in the aqueous solution of biochar and activated biochar developed from pequi (Caryocar brasiliense) endocarp. The biochar was characterized, before and after adsorption, by infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffractometry (XRD), and thermogravimetric analysis (TG). The surface load of the materials was performed by the point of zero charge (pHPZC) method. The study also included analyses of contact time parameters and adsorbed concentration in the adsorption process. Morphological analysis showed that a more significant and profound number of fissures and pores appeared in the activated biochar compared to the biochar. Residual mass analysis evidenced that biochar lost about 15% more mass than the activated biochar, indicating that activation occurred satisfactorily. The adsorption process was well adjusted by pseudo-second-order kinetics and Langmuir’s isothermal model. The activated biochar achieved an excellent adsorption capacity of 476.19 mg.g−1, thus demonstrating to be a sound system for removing dyes from an aqueous medium.

Waste generated by the textile industry is one of the primary pollutants in aquatic environments. It is estimated that about 10 to 15% of the dyes used do not chemically interact with the fabric fibers, with a loss of this pollutant in the wastewater. One of the alternatives for pollutant removal is the adsorption process, which is viable compared to other separation methods. There is a range of materials that are used in adsorption processes. Among them, polysaccharides have numerous advantages regarding their use: they are non-toxic, abundant in nature, biodegradable, hydrophilic, and have several other properties. The study aimed to investigate a novel scaffold based on biopolymers and gallium-doped hydroxyapatite for dyes removal in an aqueous solution. The scaffold was characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy, and energy dispersive X-ray spectroscopy (SEM-EDS), swelling and adsorption tests. From the XRD, the gallium presence did not change the crystal structure of hydroxyapatite. The FTIR and TG spectra of the scaffold indicate that there were interactions between the precursor materials in the production of the same by shifting the characteristic bands and increasing thermal stability. SEM showed essential characteristics for the application of scaffolds in the adsorptive process through the presence of pores on the upper side and the inner surface of the scaffold. Open and interconnected pores with average diameters in the range of 60 mm on the upper and lateral face surface and 40 mm on the inside of the scaffold were observed. A more significant number of pores were observed inside, thus influencing the adsorption. In addition, EDS was possible to qualitatively prove the presence of precursor elements for the formation of the scaffold. It is concluded that the scaffolding was successful and showed excellent potential for removing Remazol Blue RGB and Remazol Red with adsorption of 341.41 ± 6.82 and 584.89 ± 23.39 mg/g, respectively.

The hydrated phase of cobalt molybdate (H-CoMoO4) is commonly regarded as a precursor to the anhydrous phases α-CoMoO4 and β-CoMoO4. As few studies have focused on the hydrated phase, its properties should be explored. We aimed to investigate a simple method for obtaining nanosheets from a phase of CoMoO4·xH2O that aggregates to form micrometric spheroids with high surface area for antibacterial behavior. A hydrothermal synthetic route was used in the presence of urea to obtain the product, which was characterized by X-ray diffractometry, Scanning Electron Microscopy, and nitrogen adsorption–desorption isotherm for surface area analysis. The material was a finely divided purple powder. Its surface area of 22.7 m2 g−1 was determined by BET method, and its pore size distribution (mean 30 nm) was calculated by the NLDFT method. The bacterial activity of the material was evidenced by AFM, verified by the broth micro-dilution method, evidenced that H-CoMoO4 can inhibit the growth of E. coli, S. aureus, and P. aeruginosa strains, the latter achieving the best effect with Minimum Inhibitory Concentration of 1.56 mg mL−1, 1.56 mg mL−1, and 0.39 mg mL−1, respectively. This work showed the bacteriostatic effect of cobalt molybdate on surfaces for a future application in environments that facilitate microorganism proliferation.

Calcium phosphates (CaPs) have broad applications in biomedicine, with the most used phases being hydroxyapatite (HAp) and β-tricalcium phosphate (β-TCP) due to their similarity with natural bone. There are several methods for obtaining CaPs. However, the Pechini method attracts much attention due to its advantages: homogeneous molecular mixing, obtaining nanocrystalline particles, low processing temperature, generating nanometric particles, and simplicity. However, this method is little discussed for the synthesis of CaPs. This work aimed to synthesize CaPs using the Pechini method, analyzing the antibacterial properties. The samples were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG/DTG), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The XRD confirmed obtaining the biphasic ceramic of HAp, with no other phase as an impurity, where the ratio between citric acid and ethylene glycol (AC/EG) influenced the percentage of HAp phases and β-TCP formed. Thermogravimetric analysis showed a mass loss of approximately 7%. SEM observed the formation of post-agglomerates and irregular shapes. The bacteriological test was satisfactory. The samples showed above 25% inhibition for the growth of Staphylococcus aureus and Escherichia coli bacteria.

Given the increase in environmental pollution, especially of water, the emergence of studies that seek to develop strategies to mitigate/treat such effects have gained prominence in the world scientific community. Among the numerous adsorption processes, those made from biochar production stand out. This study analyzed the adsorption properties of the blue methylene model dye in the aqueous solution of biochar and activated biochar developed from pequi (

The present work aimed to characterize the exopolysaccharide obtained from water kefir grains (EPSwk), a symbiotic association of probiotic microorganisms. New findings of the technological, mechanical, and biological properties of the sample were studied. The EPSwk polymer presented an Mw of 6.35 × 105 Da. The biopolymer also showed microcrystalline structure and characteristic thermal stability with maximum thermal degradation at 250 °C. The analysis of the monosaccharides of the EPSwk by gas chromatography demonstrated that the material is composed of glucose units (98 mol%). Additionally, EPSwk exhibited excellent emulsifying properties, film-forming ability, a low photodegradation rate (3.8%), and good mucoadhesive properties (adhesion Fmax of 1.065 N). EPSwk presented cytocompatibility and antibacterial activity against Escherichia coli and Staphylococcus aureus. The results of this study expand the potential application of the exopolysaccharide from water kefir as a potential clean-label raw material for pharmaceutical, biomedical, and cosmetic applications.

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Herbicides are hazardous organic pollutants that contribute to the risk of environmental contamination. The aim of this work was to investigate the synergistic effect of silver (Ag) and gold (Au) bimetallic nanoparticles deposited on palygorskite (PAL) in the presence of TiO2 for photodegradation of bentazone (BTZ) herbicide under UV light. Ag and Au@Ag nanoparticles exhibited an average size below 75 nm and surface charge values less than − 30 mV. UV-Vis spectroscopy indicates the formation of core@shell bimetallic nanoparticles. XRD results showed the interactions between the NPs and the palygorskite structure. SEM images clearly illustrate the presence of small spherical particles distributed in the clay fibers. The control of the size and distribution of the nanoparticles played an important role in the properties of the composites. The degradation of the herbicide BTZ showed that nanoparticles, clay, and only TiO2 did not produce satisfactory results; however, when Ag-Pal and Au@Ag-Pal were in the presence of the TiO2, the degradation was efficient. The best photodegradative system was Au@Ag-Pal+TiO2, which was maintained after the third cycle. The bentazone photodegradation using Au@Ag-PAL+TiO2 exhibited toxicity against Artemia salina. Therefore, Au@Ag-PAL+TiO2 photocatalyst showed that the synergy of bimetallic nanoparticles deposited on clay for enhanced photodegradation activity of bentazone herbicide.

Flowers-like ZnO structures were synthesized using Arabic Gum (AGZnO) or Karaya Gum (KGZnO). The AGZnO and KGZnO were characterized by X-ray diffractometry, Fourier Transformed Infrared, Scanning Electron Microscopy, Photoluminescence, nitrogen adsorption/desorption and diffuse reflectance techniques. The materials were tested in the discoloration of Methylene Blue (MB) dye under visible light and scavenger studies were also performed. The toxicity of the MB irradiated was investigated in bioassays with Artemia salina. The structural characterization demonstrated the formation of hexagonal ZnO. All samples presented flower-like morphology with presence of mesopores identified by BET method. The optical properties indicated band gap of 2.99 (AGZnO) and 2.76 eV (KGZnO), and emission in violet, blue and green emissions also were observed. The KGZnO demonstrated better photocatalytic performance than the AGZnO, and scavenger studies indicated that OH radicals are the main species involved in the degradation of the pollutant model. The photodiscoloration of MB solution did not demonstrate toxicity. Therefore, KGZnO is a promising material for photocatalysis application.

Incorporation of drugs in clay minerals has been widely proposed for the controlled-release or increased solubility of drugs. In this context, a bionanocomposite based on kaolinite and cashew gum (Kln/Gum) was synthesized and characterized by X-ray diffraction (XRD), thermal analysis (TG/DTA), and Fourier transform infrared spectroscopy (FTIR). The bionanocomposite was applied to the incorporation and further release of doxazosin mesylate (DB). The influence of solution pH (1–3), adsorbent dose (20–50 mg), initial drug concentration (20.0–70.0 mg L−1), contact time (15–300 min), and temperature (25, 35, and 45 °C) were systematically evaluated. Equilibrium was reached around 60 min, with a maximum adsorption capacity of 31.5 ± 2.0 mg g−1 at a pH of 3.0 and 25 °C. Hydrogen bonding contributed to DB incorporation on the Kln/Gum. In addition, DB maximum amounts of 16.80 ± 0.58 and 77.00 ± 2.46% were released at pH values of 1.2 and 7.4, respectively. These results indicated that the Kln/Gum bionanocomposite is an effective and promising material for the incorporation/release of drugs with similar structures to DB.

A novel TiO2 photocalayst was synthesized by sol-gel method in the presence of Arabic (AGTi) and Karaya gums (KGTi). The composites were structurally and morphologically characterized by different techniques and the photocatalytic activity was investigated using methylene blue (MB) dye as model pollutant. In addition, the stability, recycle, effect of scavengers, and toxicity were investigated. The composites presented spherical structure and the nucleation of TiO2 particles was modified in presence of the gums. All the materials showed presence of the anatase phase and the textural properties indicated mesoporous and high surface area. The band gap was approximately 2.9 eV for the both materials; however the recombination process was more favored in KGTi. The C/C0 ratio of AGTi and KGTi decreased after 150 min of radiation. The electron plays the dominant role in photocatalytic process in both composites. The photocatalysts demonstrated stability after 3 runs and toxicity was not evidence in both composites. Hence, the composites showed excellent photocatalytic performance for MB discoloration.

In this work, filament based on ɛ-polycaprolactone (PCL) and containing the bioactive ceramics nanohydroxyapatite (nHap) and Laponite® (Lap) was prepared by the extrusion process. To obtain the material, a mass ratio of 89:10:1 (PCL:nHap:Lap) was used, and structural and morphological characterization was realized. In addition, cytotoxicity (using Allium cepa bulbs) and viability tests on L929 cells also were performed. The results showed that filament (diameter of 1.79 ± 0.17 mm) presented a good dispersion of nHap and Lap into polymeric matrices. Fourier transform infrared spectroscopy identified typical bands at 1720, 1091, and 1045 cm−1 addressed to PCL and nHAp, In addition, Lap was identified through dispersive energy system and X-ray diffraction analyses. All filaments did not exhibit cytotoxic effects.

Gastric ulcer is an injury that develops on the lining of the stomach due to an imbalance between aggressive and defensive agents. Chitosan derivatives demonstrate promising biological activities in accelerating the healing activity of gastric lesions. Thus, this study aimed at investigating the healing activity of gastric lesion, induced by acetic acid (80%), of the chitosan derivative with acetylacetone (Cac) modified with ethylenediamine (Cacen) or diethylenetriamine (Cacdien). The biological activity was determined based on cytotoxicity, antibacterial activity, and gastroprotective activities. The results showed no significant difference in the cytotoxicity, a better antibacterial activity against S. aureus and E. coli, and a positive result on the healing of gastric lesions of the materials (Cac 18.4%, Cacen 55.2%, and Cacdien 68.1%) compared to pure chitosan (50.7%). Therefore, the results indicate that derivatives of chitosan are promising biomaterials for application in the control of lesions on the gastric mucosa.

Water pollution has generated the need to develop technologies to remove industrial pollutants. Adsorption has been recognized as one of the most effective techniques for effluent remediation. In this study, parts (stem and leaves) of a problematic aquatic weed, the water hyacinth (

Wounds are considered a clinically critical issue, and effective treatment will decrease complications, prevent chronic wound formation, and allow rapid healing. The development of products based on naturally occurring materials is an efficient approach to wound healing. Natural polysaccharides can mimic the extracellular matrix and promote cell growth, thus making them attractive for wound healing. In this context, the aim of this work was to produce a gel based on chicha gum, chitosan, and Mauritia flexuosa oil (CGCHO) for wound treatment. TG and DTG analyzed the thermal behavior of the materials, and SEM investigated the surface roughness. The percentages of total phenolic compounds, flavonoids, and antioxidants were determined, presenting a value of 81.811 7.257 mol gallic acid/g Mauritia flexuosa oil, 57.915 0.305 mol quercetin/g Mauritia flexuosa oil, and 0.379 mg/mL, respectively. The anti-inflammatory was determined, presenting a value of 10.35 1.46% chicha gum, 16.86 1.00% Mauritia flexuosa oil, 10.17 1.05% CGCHO, and 15.53 0.65% chitosan, respectively. The materials were tested against Gram-negative (Klebsiella pneumoniae) and Gram-positive (Staphylococcus aureus) bacteria and a fungus (Candida albicans). The CGCHO formulation showed better antimicrobial activity against Grampositive bacteria. In addition, an in vivo wound healing study was also performed. After 21 days of treatment, the epidermal re-epithelialization process was observed. CGCHO showed good thermal stability and roughness that can help in cell growth and promote the tissue healing process. In addition to the good results observed for the antimicrobial, antioxidant, anti-inflammatory activities and providing wound healing, they provided the necessary support for the healing process, thus representing a new approach to the wound healing process. The authors acknowledge the Coordination for the Improvement of Higher Education Personnel, the Brazilian Ministry of Education, financial support for the scholarship. To National Council for Scientific and Technological Development (CNPq), and Piaui State Research Support Foundation (FAPEPI). The authors are thankful to CNPq for financial support (Postdoctoral fellow 164646/2020-5), and NORTE-01-0247-FEDER-113540-“Pharmapitox-Desenvolvimento de um coletor inovador e protocolo para purificação da apitoxina para uso nas indústrias farmacêutica e cosmética”. info:eu-repo/semantics/publishedVersion

This research was financially supported by Junta de Andalucia, under the project reference PT18 RT 3786., Clay minerals are often used due to their high adsorption capacity, which has sparked interest in their biological applications to stabilize drugs and pharmaceutical products. This research aims to summarize information about the stability of drugs, cosmetics, dermocosmetics, and pharmaceutical compounds incorporated in the structure of different clay minerals. The databases used to search the articles were Web of Science, Scopus, PubMed, and Science Direct. Photostabilization of these compounds is reviewed and its importance demonstrated. For biological applications, the increase in solubility and bioavailability of clay minerals has proven useful for them as drug carriers. While their natural abundance, low toxicity, and accessible cost have contributed to classical applications of clay minerals, a wide range of interesting new applications may be facilitated, mainly through incorporating different organic molecules. The search for new functional materials is promising to challenge research on clay minerals in biological or biotechnological approaches., Junta de Andalucia PT18 RT 3786

Wounds are considered a clinically critical issue, and effective treatment will decrease complications, prevent chronic wound formation, and allow rapid healing. The development of products based on naturally occurring materials is an efficient approach to wound healing. Natural polysaccharides can mimic the extracellular matrix and promote cell growth, thus making them attractive for wound healing. In this context, the aim of this work was to produce a gel based on chicha gum, chitosan, and

In recent years, anthocyanins, natural dyes, have promoted great scientific and technological interest. Their intrinsic antioxidant properties and health benefits make them ideal representatives of natural dyes as replacements for synthetic dyes. However, their instability can limit their use. A promising strategy to increase the color stability of anthocyanins is their interaction with clay minerals structures. Clay minerals have characteristics favorable to the stabilization of natural dyes, such as adsorption capacity, good surface chemistry, ion exchange capacity, abundance, non-toxicity, and environmental compatibility. This review summarizes relevant works that present different clays or clay minerals as robust inorganic matrices for incorporation, improved stability, and increased resistance against the thermal- and photodegradation of anthocyanins. In addition, several authors propose different applications for the formed anthocyanin-based hybrids.

Anthocyanins are one of the natural pigments that humanity has employed the most and can substitute synthetic food dyes, which are considered toxic. They are responsible for most purple, blue, and red pigment nuances in tubers, fruits, and flowers. However, they have some limitations in light, pH, oxygen, and temperature conditions. Combining biomolecules and inorganic materials such as clay minerals can help to reverse these limitations. The present work aims to produce materials obtained using cetyltrimethylammonium bromide in bentonite clay for incorporation and photostabilization of anthocyanin dye. Characterizations showed that the organic molecules were intercalated between the clay mineral layers, and the dye was successfully incorporated at a different pH. Visible light-driven photostability tests were performed with 200 h of irradiation, confirming that the organic–inorganic matrices were efficient enough to stabilize the quinoidal base form of anthocyanin. The pigment prepared at pH 10 was three-fold more stable than pH 4, showing that the increase in the synthesis pH promotes more stable colors, probably due to the stronger intermolecular interaction obtained under these conditions. Therefore, organobentonite hybrids allow to stabilize the fragile color coming from the quinoidal base form of anthocyanin dyes.

Chicha gum is a natural polymer obtained from the Sterculia striata plant. The hydroxyl groups of its structure have a chemical affinity to form hydrogels, which favors the association with biologically active molecules, such as nerolidol. This association improves the biological properties and allows the material to be used in drug delivery systems. Chicha gum hydrogels associated with nerolidol were produced at two concentrations: 0.01 and 0.02 g mL−1. Then, the hydrogels were characterized by thermogravimetry (TG), Fourier Transform Infrared spectroscopy (FTIR), and rheological analysis. The antibacterial activity was tested against Staphylococcus aureus and Escherichia coli. The cytotoxicity was evaluated against Artemia salina. Finally, an in vivo healing assay was carried out. The infrared characterization indicated that interactions were formed during the gel reticulation. This implies the presence of nerolidol in the regions at 3100–3550 cm−1. The rheological properties changed with an increasing concentration of nerolidol, which resulted in less viscous materials. An antibacterial 83.6% growth inhibition effect was observed using the hydrogel with 0.02 g mL−1 nerolidol. The in vivo healing assay showed the practical activity of the hydrogels in the wound treatment, as the materials promoted efficient re-epithelialization. Therefore, it was concluded that the chicha hydrogels have the potential to be used as wound-healing products.

The presence of drugs in aquatic bodies is a prevailing issue, and their removal by adsorption is an effective treatment. Among the adsorbents, those based clay minerals have been proposed. Bentonite is a clay mineral that is widely studied as an adsorbent due to its unique physicochemical properties, such as cation exchange capacity (CEC), intercalation, and adsorption. The properties of bentonites can be improved through chemical modifications, such as the incorporation of organic and/or inorganic compounds. These modifications allow for the efficient removal of different contaminants, including pharmaceutical compounds. In this work, raw sodium bentonite (Na+-Bent) and vanadyl bentonites were prepared using 100 (BentV1), 300 (BentV3), and 500% (BentV5) of the cationic exchange capacity of the Na+-Bent and further used for amiloride removal from aqueous solution. Analysis of X-ray fluorescence and Na+ in solution after interaction indicated that the principal mechanism of interaction between bentonite and ions was the ion exchange between sodium of the matrix and vanadyl in solution. Infrared spectroscopy suggested the contribution of coordination of the interlayer water with the vanadyl ions and hydrogen bonding between vanadyl and structural OH. X-ray diffraction analysis indicated that vanadyl ions were incorporated onto Na+-Bent. Amiloride adsorption was better at pH 5.8, using a solid dosage of 75 mg of Na+-Bent, 25 mg of BentV1 and BentV5, and 50 mg of BentV3. The adsorption occurred briefly until 20 min, and maximum removal values were 457.08, 374.64, 102.56, and 25.63 mg·g−1 for Na+-Bent, BentV1, BentV3, and BentV5, respectively. At lower drug concentrations (48.78 and 91.24 mg·g−1 for Na+-Bent and BentV3), the best performance was obtained for the BentV3 sample.

The development of photocatalystsor their modification to obtain new photocatalytic performances for the removal of contaminants is a challenge. Hydroxyapatite (HAp), (Ca10(PO4)6(OH)2), is an inorganic component with a high superficial area and low toxicity and the presence of metal in its structure can be an interesting strategy for the photocatalytic approach. This work aimed to synthesize gallium-containing HAp (Ga-HAp) as a promising material for photocatalytic performance. The synthesis was performed by the suspension–precipitation method. The material was characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Morphological analysis employed field emission scanning electron microscope (FESEM) and the elemental analysis by energy-dispersive spectroscopy (EDS). To evaluate the photocatalytic activity, methylene blue (MB) dye was used as a pollutant model under UV light for 120 min. The influence of Ga-HAp concentration (0.25, 0.50, and 1.00 g·L−1) and kinetic reaction was also studied. The Ga-HAp was successfully obtained by the suspension–precipitation method. The structural characterization by XRD and FESEM-EDS elucidated the presence of gallium in the structure of hydroxyapatite. The XPS results indicated the substitution of gallium in the crystal lattice of the material. The discoloration rate of MB dye using Ga-Hap was calculated by pseudo first-order kinetics, and the best rate constant was 7.5 × 10−3 min−1 using 1.00 g·L−1 of photocatalyst. The concentration of Ga-HAp influenced the photocatalytic process, because the discoloration rate increased as a function of the concentration of material. Therefore, Ga-HAp is a promising material for environmental remediation.

Mucilage extracted from chia seed (Salvia hispanica L.) (MCHs) has come to prominence in recent studies due to its attractive biological activities, improving the interest in developing Salvia hispanica as an industrial crop for sustainable source of bioactive polysaccharide. In this work, chia mucilage properties were evaluated, including physicochemical, photostability, cytocompatibility, and mucoadhesion characteristics. MCHs exhibited excellent photostability, with a degradation percentage of 6.6 % after 120 min under UV light. MTT assay results showed excellent cytocompatibility of MCHs on the L929 fibroblast cell line and additionally, the biomaterial showed promising mucoadhesive activity. Overall, the knowledge of these new properties of chia mucilage reinforces the multipotential feature of this biopolymer for application in food, cosmetic and pharmaceutical industries.

Essential oils (EOs) are complex natural mixtures of secondary plant metabolites that function as biocides and therapeutic agents. They are extensively used in bactericidal, virucidal, fungicidal, antiparasitic, insecticidal, pharmaceutical, and cosmetic products. However, certain characteristics, such as the volatility of EOs, hinder their widespread use. To mitigate this limitation, several studies have investigated combinations of EOs with natural materials, including clay minerals. Clay minerals are abundant in nature, biocompatible, and non-toxic to the environment and humans. Clay minerals such as montmorillonite possess available sites where EO molecules can interact. The combination of EOs with clay minerals produces new materials for various applications including antibacterial, antifungal, insecticidal/repellent, and active packaging materials. Therefore, this review focuses on the immobilization of several types of EOs in raw and modified montmorillonites. The applications of the described systems were evaluated and demonstrated the synergism of the properties of the isolated components as a function of different EOs incorporated in the silicate matrix.

Advances in bone defect treatment strategies have been the development of scaffolds. Among the materials used to produce scaffolds, synthetic hydroxyapatite (HAp) can simulate HAp found in human bone tissue and is used in the synthesis of scaffolds. Ion substitutions have been employed to enhance the characteristics of synthesized HAp, among them the ion exchange of Ca2+ ions for Ce3+. Biopolymers, gellan gum (GG), have potentiated the use of HAp acting as structuring agent in the composition. In this study was proposed the synthesis of two new materials, the scaffolds SH, composed by HAp with GG and, the scaffolds SCH composed by Ce-HAp and GG as materials can be potential to apply in bone defects. Scaffolds were characterized by FTIR, XRD, TG/DTG and SEM, and the techniques showed that the HAp phase and biopolymer were present in the scaffolds, besides revealed the porosity. The mechanical test showed that the scaffolds were sufficient strength to be applied as cancellous bone, implying potential for application in bone repair and regeneration.

Background The facile preparation of oxygen-generating microparticles (M) consisting of Polycaprolactone (PCL), Pluronic F-127, and calcium peroxide (CPO) (PCL-F-CPO-M) fabricated through an electrospraying process is disclosed. The biological study confirmed the positive impact from the oxygen-generating microparticles on the cell growth with high viability. The presented technology could work as a prominent tool for various tissue engineering and biomedical applications. Methods The oxygen-generated microparticles fabricated through electrospraying processes were thoroughly characterization through various methods such as X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) analysis, and scanning electron microscopy (SEM)/SEM-Energy Dispersive Spectroscopy (EDS) analysis. Results The analyses confirmed the presence of the various components and the porous structure of the microparticles. Spherical shape with spongy characteristic microparticles were obtained with negative charge surface (ζ = -16.9) and a size of 17.00 ± 0.34 μm. Furthermore, the biological study performed on rat chondrocytes demonstrated good cell viability and the positive impact of increasing the amount of CPO in the PCL-F-CPO-M. Conclusion This technological platform could work as an important tool for tissue engineering due to the ability of the microparticles to release oxygen in a sustained manner for up to 7 days with high cell viability.

Clay minerals with fibrous morphology, such as palygorskite, have been applied as adsorbents to remove pollutants from the environment and reduce toxic compounds, such as dye, in aquatic media. Although natural palygorskite has good dye removal performance, chemical modification can improve its adsorption sites and desired properties. In this study, palygorskite was activated in H2/N2 plasma flow for 2, 4, and 6 h to produce new adsorbents for the removal of methylene blue (MB). The solids were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetry, scanning electron microscopy (SEM) coupled to dispersive energy X-ray spectrometry and nitrogen adsorption/desorption measurements. The plasma technique induced structural defects in the palygorskite by the removal of coordinated and zeolitic water molecules, which altered the palygorskite’s specific surface area and pore volume. The adsorption capacity of the activated plasma samples for the removal of MB increased from 35.66 in the natural palygorskite to 54.17 mg g−1 in the activated samples. Keywords: Palygorskite, Plasma, Adsorption, Dye

Herein we present a short review of different materials and techniques that have been used for the production of surfaces with self-cleaning and/or antimicrobial properties. From this, it was verified that titanium dioxide was the most frequently used compound to obtain surfaces with these properties; however, other materials such as silica, zinc and silver have also been used for this purpose. The spin-coating and dip-coating techniques were the most used techniques, and the bacteria Staphylococcus aureus and Escherichia coli were the most used in the antimicrobial assays. The analyzed studies showed that it is possible to obtain surfaces with both self-cleaning and/or antimicrobial properties, as well as with photocatalytic activity. Regarding possible applications, it is possible to highlight the interest in the production of glass and medical devices with self-cleaning and/or antimicrobial action. Resumo Esta minirrevisão apresenta materiais e técnicas que têm sido utilizados para a produção de superfícies autolimpantes e/ou antimicrobianas. A partir dos trabalhos analisados constatou-se grande utilização do dióxido de titânio para se obter superfícies com essas propriedades, porém materiais como sílica, zinco e prata também têm sido utilizados com esse propósito. As técnicas spin-coating e dip-coating foram as mais utilizadas e as bact érias Staphylococcus aureus e Escherichia coli foram as mais empregadas nos ensaios antimicrobianos. Os trabalhos analisados mostram que é possível se obter superfícies com propriedade autolimpante e/ou antimicrobiana, além de atividade fotocatalítica. Com relação a possíveis aplicações, pode-se destacar o interesse na produção de vidros e dispositivos médicos apresentando autolimpeza e/ou ação antimicrobiana.

The great interest in compounds that present antioxidant capacity has generating the urgent need for analytical methods that could determine the antioxidant potential of these sources. A method based on generation of reactive oxygen species in water from catalyst composed of palygorskita-TiO2 and silver nanoparticles (AgNPs/TiO2-PAL) was developed and applied to antioxidant assays. Silver nanoparticles were synthesized using silver nitrate solution, sodium borohydride reducing agent and Caraia gum as stabilizing agent. Incorporation of AgNPs into the previously synthesized TiO2-PAL was performed. The catalyst AgNPs/TiO2-PAL was characterized by UV–vis spectroscopy, X-ray diffractometry and scanning electron microscopy. The catalyst AgNPs/TiO2-PAL were used to perform an antioxidant activity method which consisted in monitoring the discoloration of acid yellow 73 dye (AY73) in the presence of gallic acid antioxidant comparing to the dye discoloration in the absence of the antioxidant. A microplate reader was used to measure the discoloration of the aqueous solutions of AY73, irradiated by UV light for 60 min. The effect of reactive oxygen species generated by AgNPs/TiO2-PAL based in photocatalytic kinetics of AY73 dye was investigated. The oxidation of AY73 dye by photocatalysis in the system with AgNPs/TiO2-PAL catalysts was carried out mainly by the participation of O 2 ·− , HO· and 1O2 species, in this order of importance. The results showed that the synthesis of the AgNPs/TiO2-PAL catalyst was successfully carried out and the application of this material in the development of an innovative methodology for the determination of antioxidant activity was extremely promising.

Rigid polyurethane foams were prepared by the one-step expandable foam method using casting molding followed by forming clay-based composites. Polyurethane/vermiculite foam composites (PU/VMT) were controlled based on adding the percentage of clay in the formulation. The effects of composite modifications were evaluated by X-ray diffraction (XRD), thermogravimetric analysis (TG/DTG), and scanning electron microscopy (SEM/EDS) applied to the flame retardancy explored by the vertical burn test. The results indicated that adding clay controlled the particle size concerning polyurethane (PU) foams. However, they exhibited spherical structures with closed cells with relatively uniform distribution. XRD analysis showed the peaks defined at 2θ = 18° and 2θ = 73° relative to the crystallinity in formation and interaction of rigid segments were identified, as well as the influence of crystallinity reduction in composites. In the flame test, the flame retardant surface was successful in all composites, given the success of the dispersibility and planar orientation of the clay layers and the existence of an ideal content of vermiculite (VMT) incorporated in the foam matrix.

Agricultural production is influenced by the water content in the soil and availability of fertilizers. Thus, superabsorbent hydrogels, based on polyacrylamide, natural cashew tree gum (CG) and potassium hydrogen phosphate (PHP), as fertilizer and water releaser were developed. The structure, morphology, thermal stability and chemical composition of samples of polyacrylamide and cashew tree gum hydrogels with the presence of fertilizer (HCGP) and without fertilizer (HCG) were investigated, using X-ray diffractometry (XRD), Fourier Transformed Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA/DTG) and Energy Dispersive Spectroscopy (EDS). Swelling/reswelling tests, textural analysis, effect of pH, release of nutrients and kinetics were determined, the ecotoxicity of the hydrogels was investigated by the Artemia salina test. The results showed that PHP incorporation in the hydrogel favored the crosslinking of chains. This increased the thermal stability in HCGP but decreased the hardness and adhesion properties. The HCGP demonstrated good swelling capacity (~15,000 times) and an excellent potential for reuse after fifty-five consecutive cycles. The swelling was favored in an alkaline pH due to the ionization of hydrophilic groups. The sustained release of phosphorus in HCGP was described by the Korsmeyer–Peppas model, and Fickian diffusion is the main fertilizer release mechanism. Finally, the hydrogels do not demonstrate toxicity, and HCGP has potential for application in agriculture.