Search Results (127)

Sorption and advanced oxidative processes (AOPs) are potential strategies for the removal of organic compounds, such as caffeine, from aqueous media. Such strategies tend to be more promising when combined with biopolymeric membranes as sorbents and photocatalyst supports. Therefore, the aim of the present study was to investigate sorption and AOP parameters in the performance of chitosan membranes and chitosan/TiO₂ composite membranes in individual and hybrid systems involving the photolysis, photocatalysis, and sorption of caffeine. Caffeine degradation by photolysis was 19.51 ± 1.14, 28.61 ± 0.05, and 30.64 ± 6.32%, whereas caffeine degradation by photocatalysis with catalytic membrane was 18.33 ± 2.20, 20.83 ± 1.49, and 31.41 ± 3.08% at pH 6, 7, and 8, respectively. In contrast, photocatalysis with the dispersed catalyst achieved degradation of 93.56 ± 2.12, 36.42 ± 2.59, and 31.41 ± 1.07% at pH 6, 7, and 8, respectively. These results indicate that ions present in the buffer solutions affect the net electrical charge on the surface of the composite biomaterial with the change in pH variation, occupying active sorption sites in the structure of the biomaterial, which was characterized by Fourier transform infrared spectrometry, thermogravimetric analysis, differential scanning thermogravimetry, and X-ray diffraction. Thus, it is verified that in a combined process of caffeine removal under UV irradiation and use of chitosan/TiO₂ composite membranes in phosphate-buffered medium, the photolysis mechanism is predominant, with little or no contribution from sorption, and that the TiO₂ catalyst promotes a significant reduction in the percentage of pollutant in the medium only when used dispersed and at low pH. Full article

Fruit and vegetable production is often impacted by microbial pathogens that compromise the quality of produce and lead to significant economic losses at the postharvest stages. Due to their efficacy, agrochemicals are widely applied in disease management; nevertheless, this practice has led to the appearance of microbial strains resistant to these types of agrochemicals. Additionally, there is growing concern among consumers about the presence of these chemical residues in fruits and the negative impacts they cause on multiple ecosystems. In response, there is a growing need for safe, effective, green, and sustainable disease control technologies. Bionanocomposites, with their unique ability to combine nanomaterials and biopolymers that have attractive properties, represents a promising alternative for postharvest disease control. These technologies allow for the development of functional coatings and films with antimicrobial, antioxidant, and barrier properties, which are critical for extending shelf life and preserving fruit quality. Recent advances have demonstrated that integrating nanoparticles, such as ZnO, TiO₂, Ag, and chitosan-based nanosystems, into biopolymeric matrices, like alginate, pectin, starch, or cellulose, can enhance mechanical strength, regulate gas exchange, and control the release of active agents. This review presents systematized information that is focused on the creation of coatings and films based on bionanocomposites for the management of disease in fruits and vegetables. It also discusses the use of diverse biopolymers and nanomaterials and their impact on the quality and shelf life of fruits and vegetables. Full article

Bio-nanocomposite films were prepared using chitosan, gelatin, and varying concentrations (0, 0.5, 1.0, 2.0, and 5.0 wt%) of titanium dioxide (TiO₂) nanoparticles in acetic acid via a casting method. The incorporation of TiO₂ nanoparticles into the bio-chitosan matrix enhanced ultraviolet (UV) absorption and improved the films’ physical, mechanical, and electrical properties. Additionally, the TiO₂-loaded films exhibited antimicrobial activity, contributing to the extended preservation of packaged products by inhibiting microbial growth. Notably, the bio-nanocomposite films containing 1.0 wt% TiO₂ exhibited an electroactive response, bending under relatively low electric field strength (250 V/mm), whereas the control film without TiO₂ required higher field strength (550 V/mm) to achieve bending. This indicates potential applications in electroactive actuators requiring precise movement control. Among the tested concentrations, films containing 0.5 wt% and 1.0 wt% TiO₂ (Formulas 7 and 8) demonstrated optimal performance. These films presented a visually appealing appearance with no tear marks, low bulk density (0.91 ± 0.04 and 0.85 ± 0.18 g/cm³), a satisfactory electromechanical response at 250 V/m (17.85 ± 2.58 and 61.48 ± 6.97), low shrinkage percentages (59.95 ± 3.59 and 54.17 ± 9.28), high dielectric constant (1.80 ± 0.07 and 8.10 ± 0.73), and superior UV absorption compared with pure bio-chitosan films, without and with gelatin (Formulas 1 and 6). Full article

Sutures provide mechanical support for wound closure after various traumas and surgical operations. Absorbable sutures are increasingly favored as they eliminate the need for secondary procedures and minimize additional damage to the wound site. In this study, chitosan sutures were produced using the dry jet–wet spinning method, achieving number 7-0 sutures (approximately 76 μm diameter) with a homogeneous surface. FTIR analysis demonstrated molecular interactions between chitosan and TiO₂ or curcumin, confirming successful incorporation. The addition of 3% TiO₂ increased the tensile strength of chitosan sutures by 12.32%, reaching 189.41 MPa. Morphological analysis revealed smooth surfaces free of pores and bubbles, confirming the production of high-quality sutures. Radical scavenging activity analysis showed that curcumin-loaded sutures exhibited 43% scavenging ability after 125 h, which was significantly higher compared to pure chitosan sutures. In vitro antibacterial tests demonstrated that curcumin-loaded sutures provided 98.87% bacterial inactivation against S. aureus within 24 h. Additionally, curcumin release analysis showed a cumulative release of 77% over 25 h. The bioactivity of the sutures was verified by hydroxyapatite layer formation after incubation in simulated body fluid, supporting their potential for tissue regeneration. These findings demonstrate that TiO₂ reinforcement and curcumin loading significantly enhance the functional properties of chitosan sutures, making them strong candidates for biocompatible and absorbable surgical applications. Full article

The strong hydrophilicity of chitosan-based films limits their practical applications. To enhance the hydrophobicity of these films, hierarchical carnauba wax particles were prepared using the Pickering emulsion method and subsequently coated onto the film surfaces. The wax was stabilized with various types and concentrations of TiO₂. The resulting wax particles exhibited a micro-scale structure, with nano-scale TiO₂ and micro-scale TiO₂ aggregates present on the surface. No significant differences in contact angle were observed among these particles. Hydrophilic TiO₂ demonstrated smaller sliding angles and particle sizes. To improve the mechanical durability and compatibility of the wax particles with the chitosan matrix, the wax particles were mixed with a diluted chitosan solution before coating. As the concentration of wax particles increased and the concentration of chitosan solution decreased, more wax particles became exposed on the surface. This exposure increased the roughness of the coatings, resulting in a significant increase in contact angle and a decrease in sliding angle. A high concentration of chitosan provided greater protection to wax particles during mechanical durability tests. Additionally, the residue rate of liquid foods on the coating films significantly decreased. This study demonstrates that the Pickering emulsion method is an effective approach for preparing hierarchical wax particles, and that mixing these particles with a polymer similar to the matrix can effectively improve mechanical durability. Full article

Nitrogen oxides (NOx) and chlorinated volatile organic compounds (CVOCs) are major environmental pollutants, posing severe risks to human health and ecosystems. Traditional single-component catalysts often fail to remove both pollutants efficiently, making synergistic catalytic technologies a critical research focus. In this study, a mesoporous HPW-CS-Ce-Ti oxide catalyst, modified with H₃PW₁₂O₄₀ (HPW) and chitosan (CS), was synthesized via self-assembly. The optimized 10HPW-CS-Ce_0.3-Ti catalyst achieved nearly 100% NO conversion at 167–288 °C and a T₉₀ of 291 °C for CVOC conversion, demonstrating superior dual-pollutant removal. HPW and chitosan facilitated mesoporous structure formation, enhancing mass transfer and active site availability. HPW doping also modulated the Ce⁴⁺/Ce³⁺ ratio, boosting redox capacity and surface-active oxygen species, while increasing acidity to promote NH₃ and CVOC adsorption. This study presents a novel catalyst and synthesis method with significant potential for environmental protection and human health. Full article

This study aimed to develop and characterize bio-nanocomposite coatings by incorporating titanium nanoparticles (TiO₂ NPs) (30–50 nm) (10 mg/L), which have antimicrobial effects, and rosmarinic acid (RA) (0.005 mg/mL), which has strong antioxidant and antimicrobial activities, into the chitosan matrix using the solvent casting method. The prepared bio-nanocomposite coatings were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM-EDX), and atomic force microscopy (AFM). In the XRD analysis, the crystal structure of the bio-nanocomposite coating material was evaluated, but the absence of the expected TiO₂ NPs diffraction peak in the coating containing TiO₂ NPs was discussed in detail. The TiO₂ NPs decreased the crystallinity, compared to the control film, while rosmarinic acid increased the order of the molecular matrix. FT-IR analysis showed the presences of O–H, C=O, and C–O bonds in the coating materials, and the changes in the positions and intensities of the bands observed in the FTIR spectra of the bio-nanocomposite coatings (CHT and CHTRA) proved that TiO₂ NPs and RA were successfully integrated into the chitosan matrix. The broadening and flattening of the bands belonging to OH groups (3288–3356 cm⁻¹) indicated that the hydrogen bonds in the chitosan matrix were strengthened during the formation of the bio-nanocomposite structure. The bands representing the C=O stretching vibrations at 1659 cm⁻¹ (amide I) and the N–H bending vibrations at 1558 cm⁻¹ (amide II) indicated protein-based features in the structure of chitosan and confirmed the existence of the bio-nanocomposite structure. The SEM-EDX analysis showed that TiO₂ NPs were distributed homogeneously on the chitosan surface, but there was aggregation in places. The AFM images revealed that when TiO₂ NPs and RA were added to the chitosan matrix, the surface topography became more homogeneous, and a topographic pattern was formed in the range of 0–20.4 nm. Therefore, it is concluded that these bio-nanocomposite coatings can be used in antimicrobial surfaces and food packaging areas and should be optimized with different antioxidant and nanoparticle combinations in the future. Full article

This paper investigates the synthesis and characterization of eco-friendly piezoelectric composite thin films composed of chitosan and Ln₂O₃-doped Na_0.5Bi_0.5TiO₃-BaTiO₃ (NBT-BT) nanoparticles. The films were fabricated using a solution-casting technique, successfully embedding the particles into the chitosan matrix, which resulted in enhanced piezoelectric properties compared to pure chitosan. Characterization methods, such as photoluminescence spectroscopy and piezo-response force microscopy (PFM) which revealed strong electromechanical responses, with notable improvements in piezoelectric performance due to the inclusion of NBT-BT nanoparticles. X-ray diffraction (XRD) analysis revealed a pure perovskite phase with the space group R3c for NBT-BT and NBT-BT-Ln particles. Scanning electron microscopy (SEM) images showed a non-uniform distribution of NBT-BT particles within the chitosan matrix. The results also suggest that the incorporation of rare earth elements further enhances the electrical and piezoelectric properties of the composites, highlighting their potential in flexible and smart device applications. Overall, these findings underscore the potential of chitosan-based composites in addressing environmental concerns while offering effective solutions for energy harvesting and biomedical applications. Full article

In this work results are presented on the evaluation of HAp, HApSr, HAp_CS, and HApSr_CS layers deposited on Ti substrates regarding L929 cell viability and cytotoxicity as well as antimicrobial activity against Staphylococcus aureus, in connection with their physicochemical properties. The HAp and HApSr layers generated by radio-frequency magnetron sputtering technique were further covered with chitosan by a matrix-assisted pulsed laser evaporation technique. During the plasma depositions, the Ti substrates were heated externally by a home-made oven above 100 °C. The HApSr_CS layers generated on the unpolished Ti substrates at 100 °C and 400 °C showed the highest biocompatibility properties and antimicrobial activity against Staphylococcus aureus. The morphology of the layer surfaces, revealed by scanning electron microscopy, is dependent on substrate temperature and substrate surface roughness. The optically polished surfaces of Ti substrates revealed grain-like and microchannel structure morphologies of the layers deposited at 25 °C substrate temperature and 400 °C, respectively. Chitosan has no major influence on HAp and HApSr layer surface morphologies. X-ray photoelectron spectroscopy indicated the presence of Ca 2p_3/2 peak characteristic of the HAp structure even in the case of the HApSr_CS samples generated at a 400 °C substrate temperature. Fourier transform infrared spectroscopy investigations showed shifts in the wavenumber positions of the P-O absorption bands as a function of Sr or chitosan presence in the HAp layers generated at 25, 100, and 400 °C substrate temperatures. Full article

Recently, nanoparticles have been widely used in agricultural pest control as a secure substitute for pesticides. However, the effect of nanoparticles on controlling the subterranean termite Odontotermes formosanus (O. formosanus) has not been studied yet. Consequently, this study aimed to evaluate the effectiveness of some nanomaterials in controlling O. formosanus. The results showed that zinc oxide nanoparticles (ZnONPs), titanium dioxide nanoparticles (TiO₂NPs), and chitosan nanoparticles (CsNPs) biosynthesized using the culture filtrate of Scedosporium apiospermum (S. apiospermum) had an effective role in controlling O. formosanus. Moreover, the mortality rate of O. formosanus after 48 h of treatment with ZnONPs, TiO₂NPs, and CsNPs at a 1000 µg/mL concentration was 100%, 100%, and 97.67%, respectively. Furthermore, using ZnONPs, TiO₂NPs, and CsNPs on O. formosanus resulted in morpho-histological variations in the normal structure, leading to its death. X-ray diffraction, UV-vis spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, dynamic light scattering, energy dispersive spectroscopy, and the Zeta potential were used to characterize the biosynthesis of ZnONPs, TiO₂NPs, and CsNPs with strong activity against O. formosanus termites. Overall, the results of this investigation suggest that biosynthesized ZnONPs, TiO₂NPs, and CsNPs have enormous potential for use as innovative, ecologically safe pesticides for O. formosanus control. Full article

The UV-B component of sunlight damages the DNA in skin cells, which can lead to skin cancer and premature aging. Therefore, it is necessary to use creams that also contain UV-active substances. Many sunscreens contain titanium dioxide due to its capacity to absorb UV-B wavelengths. In the present study, titan dioxide was introduced in alginate and chitosan–alginate hydrogel composites that are often involved as scaffold compositions in tissue engineering applications. Alginate and chitosan were chosen due to their important role in skin regeneration and skin protection. The composites were cross-linked with calcium ions and investigated using FT-IR, Raman, and UV–Vis spectroscopy. The stability of the obtained samples under solar irradiation for skin protection and regeneration was analyzed. Then, the hydrogel composites were assayed in vitro by immersing them in simulated body fluid and exposing them to solar simulator radiation for 10 min. The samples were found to be stable under solar light, and a thin apatite layer covered the surface of the sample with the two biopolymers and titanium dioxide. The in vitro cell viability assay suggested that the anatase phase in alginate and chitosan–alginate hydrogel composites have a positive impact. Full article

Overly fast corrosion degradation of biodegradable magnesium alloys has been a major problem over the last several years. The development of protective coatings by using biocompatible, biodegradable, and non-toxic material such as chitosan ensures a reduction in the rate of corrosion of Mg alloys in simulated body fluids. In this study, chitosan/TiO₂ nanocomposite coating was used for the first time to hinder the corrosion rate of Mg19Zn1Ca alloy in Hank’s solution. The main goal of this research is to investigate and explain the corrosion degradation mechanism of Mg19Zn1Ca alloy coated by nanocomposite chitosan-based coating. The chemical composition, structural analyses, and corrosion tests were used to evaluate the protective properties of the chitosan/TiO₂ coating deposited on the Mg19Zn1Ca substrate. The chitosan/TiO₂ coating slows down the corrosion rate of the magnesium alloy by more than threefold (3.6 times). The interaction of TiO₂ (NPs) with the hydroxy and amine groups present in the chitosan molecule cause their uniform distribution in the chitosan matrix. The chitosan/TiO₂ coating limits the contact of the substrate with Hank’s solution. Full article

This research investigates the influence of synthesis kinetics on the structural and photocatalytic properties of chitosan–clay nanocomposites (Cs/MMT) and chitosan–hectorite nanocomposites (Cs/HET), employing an optimized initial stoichiometry of 1:3. Utilizing a variety of analytical techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR), the study explores the structural evolution of the nanocomposites and their photocatalytic performance using semiconductor catalysts TiO₂ and ZnO. The findings emphasize the significant impact of reaction kinetics, particularly after 3 h of reaction time, on the structural features of the nanocomposites. Notably, Cs/MMT demonstrates greater crystalline stability compared to Cs/HET due to variations in octahedral cavity occupancy in the initial clays. FTIR and TEM analyses depict the progressive evolution of the nanocomposites during the reaction, shedding light on how reaction kinetics drive the formation of specific bonds within the nanocomposites. In terms of photocatalytic activity, this study provides insights into the complex dynamics of photocatalytic degradation, with a specific focus on the performance of TiO₂ and ZnO under diverse experimental conditions. The superior efficacy of TiO₂ as a catalyst, particularly when integrated with Cs/MMT nanocomposites, is unequivocally demonstrated, with degradation rates exceeding 80%. This preference stems from TiO₂ consistently exhibiting higher degradation rates compared to ZnO, attributed to structural disparities between montmorillonite and hectorite, influencing catalyst–support interactions. The findings underscore the critical importance of selecting suitable catalyst and support matrix combinations for optimizing performance in specific applications. Full article

Peri-implantitis is a growing pathological concern for dental implants which aggravates the occurrence of revision surgeries. This increases the burden on both hospitals and the patients themselves. Research is now focused on the development of materials and accompanying implants designed to resist biofilm formation. To enhance this endeavor, a smart method of biofilm inhibition coupled with limiting toxicity to the host cells is crucial. Therefore, this research aims to establish a proof-of-concept for the pH-triggered release of chlorhexidine (CHX), an antiseptic commonly used in mouth rinses, from a titanium (Ti) substrate to inhibit biofilm formation on its surface. To this end, a macroporous Ti matrix is filled with mesoporous silica (together referred to as Ti/SiO₂), which acts as a diffusion barrier for CHX from the CHX feed side to the release side. To limit release to acidic conditions, the release side of Ti/SiO₂ is coated with crosslinked chitosan (CS), a pH-responsive and antimicrobial natural polymer. Scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX) and Fourier transform infrared (FTIR) spectroscopy confirmed successful CS film formation and crosslinking on the Ti/SiO₂ disks. The presence of the CS coating reduced CHX release by 33% as compared to non-coated Ti/SiO₂ disks, thus reducing the antiseptic exposure to the environment in normal conditions. Simultaneous differential scanning calorimetry and thermogravimetric analyzer (SDT) results highlighted the thermal stability of the crosslinked CS films. Quartz crystal microbalance with dissipation monitoring (QCM-D) indicated a clear pH response for crosslinked CS coatings in an acidic medium. This pH response also influenced CHX release through a Ti/SiO₂/CS disk where the CHX release was higher than the average trend in the neutral medium. Finally, the antimicrobial study revealed a significant reduction in biofilm formation for the CS-coated samples compared to the control sample using viability quantitative polymerase chain reaction (v-qPCR) measurements, which were also corroborated using SEM imaging. Overall, this study investigates the smart triggered release of pharmaceutical agents aimed at inhibiting biofilm formation, with potential applicability to implant-like structures. Full article