Tannic Acid Research Articles

Precision management of Fusarium fujikuroi in rice through seed coating with an enhanced nanopesticide using a tannic acid-ZnIIformulation.

Seed coating with fungicides is a common practice in controlling seed-borne diseases, but conventional methods often result in high toxicity to plants and soil. In this study, a nanoparticle formulation was successfully developed using the metal-organic framework UiO-66 as a carrier of the fungicide ipconazole (IPC), with a tannic acid (TA)-ZnII coating serving as a protective layer. The IPC@UiO-66-TA-ZnII nanoparticles provided a controlled release, triggered and regulated by environmental factors such as pH and temperature. This formulation efficiently controlled the proliferation of Fusarium fujikuroi spores, with high penetration into both rice roots and fungal mycelia. The product exhibited high antifungal activity, achieving control efficacy rates of 84.09% to 93.10%, low biotoxicity, and promoted rice growth. Compared to the IPC flowable suspension formula, IPC@UiO-66-TA-ZnII improved the physicochemical properties and enzymatic activities in soil. Importantly, it showed potential for mitigating damage to beneficial soil bacteria. This study provides a promising approach for managing plant diseases using nanoscale fungicides in seed treatment.

Antibiotic-Augmented Chemodynamic Therapy for Treatment of Helicobacter pylori Infection in the Dynamic Stomach Environment.

Helicobacter pylori (H. pylori) is one of the main causes of peptic ulcer disease and gastric cancer. The overuse of antibiotics leads to bacterial drug resistance and disruption to the gut microbiome. Herein, a nanoparticle (TA-FeHMSN@Amox) was developed, comprising amoxicillin (Amox)-loaded iron-engineered hollow mesoporous silica as the core and a metal-polyphenol shell formed by tannic acid (TA) and Fe3+. In acidic stomach conditions, TA-FeHMSN@Amox generates bactericidal ·OH through Fenton/Fenton-like reactions of the degraded product Fe2+ and hydrogen peroxide (H2O2) at the infection site, achieving chemodynamic therapy (CDT). Moreover, released amoxicillin enhances therapeutic efficacy by impeding the self-repair of the bacterial cell wall damaged by CDT, overcoming the limitations of ineffective CDT under conditions lacking sufficient acidity and H2O2. The acidity-responsive CDT combined with reduced antibiotic usage ensures superior in vivo therapeutic efficacy and biocompatibility with intestinal flora, providing a highly potent strategy for treating H. pylori infections in the dynamic stomach environment.

Biofilm targeting with chitosan-based nanohydrogel containing Quercus infectoria G. Olivier extract against Streptococcus mutans: new formulations of a traditional natural product.

Biofilm formation has a crucial role in the cariogenic virulence of Streptococcus mutans, which leads to resistance to common antibacterials. The antimicrobial resistance crisis has led to increased research about traditional natural products. Quercus infectoria extract (QI extract) and nano hydrogels containing QI extract (QI-NH) and tannic acid (TA-NH) were evaluated against this pathogen. QI extract was analyzed by HPLC and the physiological characteristics of nanohydrogels were assessed by SEM, FTIR, zeta potential, DLS and determination of release kinetics and encapsulation efficiency. Determination of MIC and MBC of the material and their anti-biofilm effect was done by the microtiter method and on the extracted tooth surface. The properties of extracts and nano hydrogels in the expression of genes codifying glucosyltransferases (gtfB, gtfC and gtfD) and glucan binding protein B (gbpB) were quantified. Their toxicity was tested by the MTT method against the KB cell line. According to HPLC, 55.18% of QI extract contained TA. The encapsulation efficiency of QI-NH and TA-NH was equal to 60% and 80%, respectively. SEM and FTIR exhibited that QI extract and TA were successfully entrapped in the networks resulting from the chemical bonding of chitosan and TPP. The average size of QI-NH and TA-NH was 70.45 and 58.43nm, and their zeta potential was 6.17 ± 2.58 and 0.25 ± 0.03 mv, respectively. PDI < 0.3 of nano hydrogels indicated the favorable polydispersity of nanohydrogels. MIC of QI extract, QI-NH and TA-NH were 937.5, 30 and 10µg/ml, respectively. Also their MBIC50 was 35.1, 2.1 and 0.95µg/ml, respectively, and the extracts and nano hydrogels restrained the biofilm maturation on enamel. The pivotal genes of S. mutans in biofilm formation were significantly less expressed by treatment with QI-NH and TA-NH than others. Based on the MTT test, QI-NH had less acute toxicity than QI extract and TA-NH. IC50 of QI-NH was calculated as 775.4µg/ml, while it was equal to 3.12µg/ml for chlorhexidine as a common antibacterial agent. QI-NH, a new formulation derived from traditional anti-caries, can be a safe and efficient option to combat dental biofilm.

An in Vitro Assessment of the Retentive Property of Orthodontic Molar Bands Cemented With HY Agent-Containing Glass Ionomer Cement

Introduction: In orthodontic treatments, glass ionomer cements (GICs) are the most extensively used adhesive materials. Through an acid-base reaction with enamel and dentin, they function as chelating agents, creating a chemical bond with stainless steel bands. It has been reported that glass ionomer cement (GIC) containing HY agents along with a complex of zinc fluoride, strontium fluoride, and tannic acid offers enhanced retentive strength. This combination contributes to reduced solubility, promotes remineralization, and improves acid resistance. In this in vitro study, Shofu HY Bond glass ionomer cement (HY GIC) was utilized to compare and evaluate the retentive strength of molar bands cemented with it against Voco Meron (VM GIC), a conventional glass ionomer cement.Materials and Methods: The long axis of fifty extracted maxillary first molars was aligned at 90 degrees to the acrylic resin blocks. Of these teeth, twenty-five were bonded using HY-GIC (group 1), while the remaining twenty-five were bonded with Meron GIC (group 2). The retentive properties of both types of glass ionomer cement were evaluated using universal testing equipment. An independent t-test was employed to compare the retentive strength between the two groups.Results: The average retentive strength of bands bonded with HY-GIC was measured at 14.65 ± 1.37 MPa, while bands using Meron GIC had a strength of 10.75 ± 1.10 MPa. The difference between these two values was statistically significant.Conclusion: There was a significant difference in the retentive strength between the 2 groups with Shofu HY bond GIC being superior.

Improvement of dispersants on nano carbon black-modified cement paste: performance, microstructure and carbon footprint

The agglomeration of nano carbon black (NCB), driven by its high specific surface energy, limits the fundamental performance of cementitious materials and hinders the broader application of functional cementitious materials in engineering domains. NCB-modified cement (NC) has a low snow-melting efficiency, resulting in high energy consumption and excessive CO2 emissions. Herein, this study innovatively proposed a method of using dispersants to overcome the above issue and systematically introduced the effects of three dispersants, polycarboxylic acid superplasticizer (PCE), tannic acid (TA), and sodium dodecyl sulfate (SDS), on NC. The dispersity of dispersant-NCB suspension was analyzed firstly, and then the performance of fresh paste, mechanical properties, resistivity, snow-melting speed and LCA of NC were explored. Experimental results indicated that, in terms of suspension stability, SDS was the most effective, followed by TA, while PCE exhibited the least efficacy. Furthermore, all three dispersants improved the fluidity of NC to varying degrees. However, PCE and TA demonstrated a retardation effect on the setting time, whereas SDS facilitated a reduction in the setting time of NC. From the point of view of mechanical properties, the use of these dispersants not only augmented the mechanical strength of the NC but also decreased its electrical resistivity. The uniform dispersion of SDS at the microstructural level of NCB had also been found. When the PCE content is 0.2%, TA content is 0.4%, and SDS content is 0.4%, the mechanical strength and resistivity of NC were the best. NC with dispersant TA melted snow three times faster than the control group, reducing snow-melting energy consumption. Moreover, LCA analysis showed that the addition of dispersants also reduced carbon emissions.

Assembly of Silicate-Phenolic Network Coatings with Tunable Properties for Controlled Release of Small Molecules.

Engineered coatings are pivotal for tailoring the surface properties and release profiles of materials for applications across diverse areas. However, developing robust coatings that can both encapsulate and controllably release cargo is challenging. Herein, a dynamic covalent coordination assembly strategy is used to engineer robust silicate-based coatings, termed silicate-phenolic networks (SPNs), using sodium metasilicate and phenolic ligands (tannic acid, gallic acid, pyrogallol). The coatings are pH-responsive (owing to the dynamic covalent bonding), and their hydrophobicity can be tuned upon their post-functionalization with hydrophobic gallates (propyl, octyl, lauryl gallates). The potential of the SPN coatings for the controlled release of small molecules, such as urea (a widely used fertilizer), is demonstrated-controlled release of urea in soil is achieved in response to different pHs (up to 7 days) and different hydrophobicity (up to 14 days). Furthermore, leveraging the presence of silicon (within the coating) and post-functionalization of the SPN coatings with metal ions (Fe3+, Cu2+, Zn2+) generates a multipurpose delivery system for the sustained release of micronutrient fertilizers, and silicon and metal ions, over 28 and 14 days, respectively. These SPN coatings have potential applications beyond agriculture, including nutrient delivery, separations, food packaging, and medical device fabrication.

A novel multifunctional nanocomposite hydrogel orchestrates the macrophage reprogramming-osteogenesis crosstalk to boost bone defect repair.

Repairing bone defects is a complex cascade reaction process, as immune system regulation, vascular growth, and osteogenic differentiation are essential. Thus, developing a tissue-engineered biomaterial that caters to the complex healing process of bone regeneration remains a major clinical challenge. In the study, Ca2+-TA-rGO (CTAG)/GelMA hydrogels were synthesized by binding Ca2+ using metal chelation to graphene oxide (GO) nanosheets reduced by tannic acid (TA-rGO) and doping them into gelatin methacrylate (GelMA) hydrogels. TA and rGO exhibited biocompatibility and immunomodulatory properties in this composite, while Ca2+ promoted bone formation and angiogenesis. This novel nanocomposite hydrogel demonstrated good mechanical properties, degradability, and conductivity, and it could achieve slow Ca2+ release during bone regeneration. Both in vitro and in vivo experiments revealed that CTAG/GelMA hydrogel modulated macrophage reprogramming and induced a shift from macrophages to healing-promoting M2 macrophages during the inflammatory phase, promoted vascular neovascularization, and facilitated osteoblast differentiation during bone formation. Moreover, CTAG/GelMA hydrogel could downregulate the NF-κB signaling pathway, offering new insights into regulating macrophage reprogramming-osteogenic crosstalk. Conclusively, this novel multifunctional nanocomposite hydrogel provides a multistage treatment for bone and orchestrates macrophage reprogramming-osteogenic crosstalk to boost bone repair.

The tannin acid /Fe3+ composite film filled with essential oil extracted from Melaleuca bracteata F. Muell leaves for the preservation of mangos.

Tannic acid and Fe3+ were used in this study to create a polyphenol-metal network-based composite film for the preservation of Melaleuca bracteata essential oils. The inhibition rate of ABTS and DPPH free radicals reached more than 90% at an essential oil concentration of 20 mg/mL. Additive quantities of 2.0% essential oil nano-emulsion, 0.8% tannic acid/Fe3+ solution, 0.4% microcrystalline cellulose, and 1% chitosan were used to maximize the characteristics of the composite films. When combined with FTIR analysis, X-ray diffraction and scanning electron microscopy revealed that the composite film containing the essential oil emulsion had a more reticulated structure. The essential oil composite layer on mangoes increased the fruit shelf time to 12 days, decreased weight loss by 10.81±4.70%, increased the amount of soluble solids by 2.03±0.31%, and increased the amount of vitamin C by 2.18±0.09%. A trustworthy technical method for the storage and transportation of agricultural goods is offered by this study.

Oral administration of tannic acid attenuates dyslipidemia, hyperglycemia, and oxidative stress in high‐fat and fructose diet‐induced obesity in rats

AbstractObesity and diabetes are considered life‐threatening conditions, characterized by increased oxidative stress, insulin resistance, hepatotoxicity, hyperglycemia, and hypercholesterolemia. Therefore, we studied the effects of tannic acid in a high‐fat and fructose‐diet‐induced rat model of obesity. Administration of tannic acid at doses of 200 and 400 mg/kg significantly reduced fasting blood glucose concentration, reversed disoriented lipid profile, decreased liver enzyme activities, and inhibited oxidative stress compared to the high‐fat, high‐sugar group. Histopathological examination showed preserved pancreas and liver architecture in the tannic acid‐administered groups. The in vitro inhibitory activity of tannic acid against alpha‐amylase, alpha‐glucosidase, and pancreatic lipase showed good inhibitory potential. Molecular docking studies showed high binding affinity and more hydrogen bond interactions between tannic acid and receptor proteins (alpha‐amylase, alpha‐glucosidase, and pancreatic lipase) implicated in obesity and diabetes. In conclusion, tannic acid prevented the onset of oxidative stress, preserved the liver, and restored the disoriented lipid profile in high‐fat and fructose diet‐induced obesity in rats.

A facile and sustainable preparation of effective biomass macromolecular flame retardants for epoxy resins with improved flame retardation, smoke suppression, and mechanical performance

AbstractThe preparation of biomass flame retardants with efficient flame‐retardant properties is conducive to the realization of sustainable development and is of great practical significance. In this work, a green and sustainable biomass flame retardant PATAPEI was prepared by using phytic acid (PA), tannic acid (TA), and polyethyleneimine (PEI) as reactants via a one‐step method to develop biomass flame retardants that can synchronize enhanced flame retardation, smoke suppression, and mechanical performance of epoxy resin (EP). The EP with only a 3% PATAPEI (EP/3PTP) has a LOI value of 28.5% with a UL‐94 V‐0 classification. The peak heat release rate (PHRR), total heat release (THR), and total smoke release (TSR) of EP/3PTP were decreased by 29.72%, 25.80%, and 21.16%, respectively, in comparison with the ones of pure EP. Additionally, the tensile and impact strengths of EP/3PTP are higher than the ones of pure EP. PATAPEI on heating decomposes to produce phosphorus‐containing acids and biphenyltriol‐containing compounds, which promote to form a good char layer with the aromatic structures during the combustion of EP/3PTP. Therefore, PATAPEI has prospects of wide application in the development of sustainable biomass flame retardant EP.

3D printed sodium alginate/gelatin/tannic acid/calcium chloride scaffolds laden bone marrow mesenchymal stem cells to repair defective thyroid cartilage plate.

Due to the absence of blood vessels, cartilage exhibits extremely limited self-repair capacity. Currently, repairing laryngeal cartilage defects, resulting from conditions such as laryngeal tumors, injury, and congenital structural abnormalities, remains a significant challenge in the Department of Otolaryngology, Head and Neck Surgery. Previous research has often focused on enhancing the mechanical properties of synthetic materials. However, their low biological activity and weak cell adhesion necessitate compensatory measures. This study aims to capitalize on the advantages of natural materials in cartilage tissue engineering. Sodium alginate, gelatin, tannic acid, and calcium chloride were utilized to prepare bioinks through cross-linking for application in 3D printing cartilage scaffolds. Bone marrow mesenchymal stem cells with multidirectional differentiation potential were chosen as seed cells, with appropriate growth factors incorporated to promote their differentiation into cartilage during in vitro culture. The scaffold laden cells was subsequently implanted into rabbit thyroid cartilage plate defects at the appropriate time. HE staining, toluidine blue staining, Masson staining, and collagen type II staining were employed to assess cartilage defect repair at 4, 8, and 12 weeks, respectively. Results demonstrated that scaffolds made from natural materials could emulate the mechanical properties of fresh cartilage with commendable biocompatibility. Stained sections further confirmed the efficacy of the composite hydrogel scaffolds identified in this study in promoting rabbit thyroid cartilage plate restoration. In summary, this study successfully fabricated a natural material scaffold for rabbit laryngeal cartilage tissue engineering, thereby furnishing a new idea and experience for the clinical application of laryngeal cartilage defect reconstruction.

Broad-Spectrum Bactericidal Multifunctional Tiny Silicon-Based Nanoparticles Modified with Tannic Acid for Healing Infected Diabetic Wounds.

Infected chronic wounds, in particular, diabetic wounds, are hard to heal, posing a global health concern with high morbidity and mortality rates. Diabetic full-thickness wounds infected with E. coli belong to the most difficult to heal chronic infected wounds. Here, we introduced tannic acid-modified silicon-based nanoparticles (TA-SiNPs) with broad-spectrum bactericidal activity that bacteria develop minimal resistance to, and they can effectively treat full-thickness wounds in diabetic mice infected with E. coli. Our findings indicate that these TA-SiNPs could achieve 100% antibacterial efficiency against S. aureus and 99.83% against E. coli, underlied by a positive surface charge and tannic acid groups facilitating bacterial membrane chemical composition depletion and depolarization of the membrane. In addition, we showed that spraying TA-SiNPs onto the skin wound of diabetic mice infected with E. coli resulted in wound healing with 98% closure after 12 days, in stark contrast to 49% of the control (PBS) and 68% of the one treated with Ofloxacin. Along with infection inhibition and ROS scavenging, we identified cell proliferation stimulation, inflammatory cytokine downregulation, and healing cytokine upregulation in the lesion, favoring the healing process. This study not only demonstrates the feasibility of employing silicon-based nanoparticles in diabetic wound healing for the first time, but also reports the first broad-spectrum bactericidal silicon nanodots. Furthermore, this provides novel insights into the mechanism of tannin-based nanoparticles disrupting bacterial membranes by depleting their chemical constituents. Our results highlighted that the developed TA-SiNPs are an effective nanomaterial for treating the infected chronic wounds.

Innovative biopolymers composite based thin film for wound healing applications

Efficient wound and burn healing is crucial for minimising complications, preventing infections, and enhancing overall well-being, necessitating the development of innovative strategies. This study aimed to formulate a novel thin film combining chitosan, carboxymethyl cellulose, tannic acid, and beeswax for improved wound healing applications. Several formulations, incorporating chitosan, carboxymethyl cellulose, tannic acid, and beeswax in various percentages, were utilized to deposit thin films via the solvent evaporation technique, Mechanical properties, morphology, antioxidant activity, antibacterial efficacy, and wound healing potential were evaluated. The optimized thin film (M4), composed of 2% chitosan, 2% carboxymethyl cellulose, and 1% tannic acid, along with 0.2% glycerol and 0.2% tween80, exhibited a thickness of 39.0 ± 1.14 μm and a tensile strength of 0.275 ± 0.003 MPa. It demonstrated a swelling degree of 283.0 ± 2.0% and a drug release capacity of 89.4% within 24 h. The film also showed a low contact angle of 40.5° and a water vapour transmission rate of 1912.25 ± 13.10 g m−2 0.24 h−1. FT-IR spectroscopy indicated that chitosan and carboxymethyl cellulose were cross-linked through amide linkages, with tannic acid occupying the interstitial spaces and hydrogen bonding stabilizing the structure. Microscopy of M4 revealed a uniform morphology. The film exhibited strong antioxidant activity of (95.17 ± 0.02%) and antibacterial efficiency (80.8%) against S. aureus. In a rabbit model, the film significantly enhanced burn and excision wound recovery, with 90.0 ± 3.3% healing for burns and 88.85 ± 1.7% for infected wounds by day 7. Complete skin regeneration was observed within 10–12 days. The M4 thin film demonstrated exceptional mechanical properties and bioactivity, offering protection against pathogens and promoting efficient wound healing. These findings suggest its potential for further investigation in treating various infections and its role in developing novel therapeutic interventions.

Preparation of tannic acid-based recyclable adhesive with high adhesion property, low curing temperature, and environmental tolerance

Tannin-based adhesives have demonstrated promise in decreasing dependence on petrochemical resources linked to formaldehyde-based resins. However, current tannin-based adhesives face challenges due to the incorporation of expensive or toxic reagents such as isocyanate, epoxy, and formaldehyde, as well as the inability to be recycled. This study presents a simple and eco-friendly approach for producing a tannic acid-based recyclable adhesive (TA-BVB) by employing tannic acid and 1,4-butanediol divinyl ether through acetal reactions. The resulting adhesive can be cured at a low temperature of 70℃ and demonstrated high bonding strength on wood and aluminum sheets, measuring 4.45 MPa and 5.44 MPa, respectively. Notably, the adhesive maintained its adhesion strength even under harsh conditions, including high temperatures (100℃), liquid nitrogen (-196℃), and exposure to various solvents. Moreover, the adhesive showcased excellent reusability, retaining over 100 % and 86 % of bonding strength after the first and second rounds of hot pressing, respectively. This adhesive can be repaired using infrared laser irradiation and displayed remarkable mold resistance. This research underscores the potential of tannic acid in developing environmentally friendly, high-performance, recyclable adhesives with versatile applications.

Iron-Tannin Coating Reduces Clearance and Increases Tumor Colonization of Systemically Delivered Bacteria.

Engineered bacteria offer a novel approach to targeted cancer therapy, but challenges remain in delivering enough bacteria safely for effective treatment. Previous efforts have used either a native or synthetic coating to achieve better control over the half-life of bacteria in the body but have limitations in delivery or versatility. In this work, we optimized and evaluated a synthetic coating for probiotic Escherichia coli Nissle 1917 to increase its half-life in blood and thereby increase the bioavailability of intravenous doses of bacteria to colonize and treat tumors. Using a simple one-pot chemical process, we coated bacteria with iron and tannic acid (FeTA) to form a temporary adhesive protective coating surrounding the bacterial cell surface. The iron to tannic acid ratio of the coating was optimized for intravenous use, and FeTA-coated bacteria of several different genetic backgrounds showed 15-fold higher survival in blood survival assays for up to 4 hours. We found that the FeTA coating reduced both complement-mediated bacterial killing and phagocyte-mediated bacterial killing in vitro. As a result, systemic delivery of attenuated bacteria had up to 60% colonization efficiency of FeTA-coated bacteria in an orthotopic breast cancer mouse model compared to 10% for the non-coated control, all the while maintaining a two-fold decrease in weight loss of attenuated bacteria compared to wild-type. Altogether, we show that an optimized FeTA coating significantly extends the half-life and colonization efficiency of engineered bacteria, overcoming a key limitation of their application in cancer therapy.

Reinforcing polyvinyl alcohol films with layered double hydroxide and tannic acid to enhance tensile strength, tribological performance, and corrosion resistance in biomedical coating applications

Abstract This study investigates the synergistic effects of incorporating layered double hydroxide (LDH) and tannic acid (TA) into polyvinyl alcohol (PVA) films to enhance their mechanical, tribological, and corrosion resistance properties for biomedical applications. Composite coating films were prepared by blending PVA with LDH and TA in various concentrations. The addition of LDH and TA significantly increased the crystallinity index of the composite films, with the highest crystallinity observed at 66.3% for the sample containing 1 wt% TA and 2 wt% LDH (PVA/TA1/LDH2). This enhancement in crystallinity contributed to improved mechanical performance, as demonstrated by tensile tests, where the PVA/TA1/LDH2 composite exhibited the highest tensile strength among all samples. Tribological testing revealed that the PVA/TA1/LDH2 composite also achieved the lowest coefficient of friction (COF), along with a minimal wear rate, indicating superior wear resistance. SEM analysis of the wear scars confirmed a narrow wear track and smoother surface morphology for this composite, which suggests effective load distribution and reduced surface degradation. The addition of TA was further shown to improve the corrosion resistance of the PVA composite films, with the PVA/TA1/LDH1 sample exhibiting the lowest corrosion current density (Icorr) of 0.36 µA cm⁻², representing a significant improvement over neat PVA. These findings highlight the potential of PVA/LDH/TA films for coating applications in biomedical devices, where enhanced mechanical strength, wear resistance, and corrosion protection are critical. The synergistic effects of LDH and TA provide a pathway for developing durable and functional coatings, expanding the practical utility of PVA films in demanding biomedical environments.&amp;#xD;

Improved Emulsifying Performance of Agarose Microgels by Cross-Interfacial Diffusion of Polyphenols.

Noninterface-active polysaccharides can acquire better emulsifying properties through microgelation, yet optimizing their emulsifying performance remains a significant challenge. This study introduces a novel approach to enhance the emulsifying performance of polysaccharide microgels by leveraging the cross-interfacial diffusion of polyphenols, which promotes the interfacial adsorption of microgels. Tannic acid (TA) was predispersed in oil phases and subsequently emulsified with agarose microgel (AM) suspensions, and the impacts of TA diffusion on the emulsifying performance of AMs was investigated. In addition, the transmittance profiles of oil-water biphasic systems were found to innovatively indicate the cross-interfacial diffusion of TA and the interfacial adsorption of AMs. The current results suggest that an appropriate level of TA incorporation can benefit the emulsifying performance of AMs, correlating with decreased droplet sizes and improved physical stability of the emulsion. However, excessive TA might trigger the clustering of AMs before they reach the interfacial layer, adversely affecting the emulsion stability. In conclusion, the cross-interfacial diffusion of polyphenols offers a promising strategy to overcome the stability challenges encountered in polysaccharide microgel-stabilized emulsions.

From Burst to Sustained Release: The Effect of Antibiotic Structure Incorporated into Chitosan-Based Films

Background/Objectives: Medical devices are susceptible to bacterial colonization and biofilm formation, which can result in severe infections, leading to prolonged hospital stays and increased burden on society. Antibacterial films have the potential to assist in preventing biofilm formation, thereby reducing administration of antibiotics and the emergence of antibiotic-resistant strains. In a previous study, a chitosan-based matrix crosslinked with tannic acid and loaded with gentamicin was reported. In this study, five different antibiotics (moxifloxacin, ciprofloxacin, trimethoprim, sulfamethoxazole or linezolid) were loaded into these chitosan-based films, and their impact on the release behavior carefully assessed. Methods: The samples were characterized according to their thickness, swelling, and mass loss in phosphate-buffered saline (PBS), as well as by morphology using scanning electron microscopy (SEM) and optical phase contrast microscopy. Antibiotic release over time was quantified in PBS by high-performance liquid chromatography (HPLC). Antibacterial activity was investigated by disk diffusion test and antibiotic release over time. Finally, the cytotoxicity of the samples was assessed with human dermal fibroblasts. Results: The obtained results differed significantly, especially regarding the antibiotic release time and antibacterial activity, which varied from one day to six months, enabling classification of the films from burst/transient to prolonged release. The films also showed antibacterial features against bacteria mostly present in medical devices and displayed to be non-cytotoxic. Conclusions: In conclusion, it was demonstrated that the antibiotics structure significantly alters the release kinetics, and that by carefully selecting the antibiotic, the consequent release can be tuned. This approach yielded films that could be used for potentially-scalable release in antimicrobial coatings specific to medical devices, aiming to reduce biomaterial associated infections (BAIs).

Hormesis and Antagonism in Low-Dose Phalaris Allelochemicals during Microcystis Control

Aquatic ecosystems face significant challenges globally from cyanobacterial blooms. Phalaris arundinacea (Reed Canary Grass) is used in artificial wetlands and found in natural wetlands. We investigated whether allelochemicals released from Phalaris root exudates inhibit Microcystis aeruginosa growth. We conducted experiments to disentangle the effect of the root exudates from living plants on resource competition and the potential role of microbiota in controlling Microcystis growth. We found that allelochemicals from root exudates and their inhibitory effect decayed over time. Results from filtration experiments and microscopic observations indicated that the removal of microorganisms (≥ 0.22 µm) allowed for the growth of Microcystis, suggesting that protists and rotifers may control Microcystis growth. We also tested commercial allelochemicals at environmentally relevant concentrations (≤ 1000 µg Lˉ¹) against Microcystis. Concentrations of 1000 µg Lˉ¹ of anthraquinone, gallic acid, gramine, hordenine, linoleic acid, naringuin, stigmasterol, tannic acid, 4-nitroindol-5-carboxaldehyde and the mixture of the nine allelochemicals inhibit Microcystis (≥ 87%). The minimum effective concentration was determined to be 100 µg Lˉ¹ for most allelochemicals, except for anthraquinone, which had a hormetic effect stimulating Microcystis growth by up to 70% compared to the controls. Our findings indicate that allelochemicals could be used to control Microcystis, but it is essential to establish the effective allelochemical minimum inhibitory concentrations from biofilters, wetlands, or macrophytes to assess their potential for managing Microcystis, other cyanobacteria, and microalgae. The increasing global use of artificial wetlands to control cyanobacterial blooms justifies further investigation into allelochemical concentrations, including decaying trends over time and hormetic effects.

Highly Sensitive and Biocompatible Microsensor for Selective Dynamic Monitoring of Dopamine in Rat Brain.

Highly selective and sensitive in vivo neurotransmitter dynamic monitoring of the central nervous system has long been a challenging endeavor. Here, an implantable and biocompatible microsensor with excellent performances was reported by electrodepositing poly(3,4-ethylenedioxythiophene)-electrochemically reduced graphene oxide (PEDOT-ERGO) nanocomposites and poly(tannic acid) (pTA) sequentially on the carbon fiber electrode (CFE) surface, and its feasibility in in vivo electrochemical sensing applications were demonstrated. Due to the synergistic electrocatalytic effect of PEDOT-ERGO nanocomposites with the negative-charged pTA on dopamine (DA) redox reaction, the microsensor exhibits high detection sensitivities of 1.1 and 0.37 nA μM-1 in the detection ranges of 0.02-0.5 and 0.5-20 μM with a low limit of detection of 9.2 nM. Also, the microsensor shows excellent selectivity, good sensing stability, repeatability, and reproducibility. In addition, the highly hydrophilic and negative-charged pTA inhibits the nonspecific adsorption of hydrophobic proteins, which endows the microsensor with good antifouling ability. Moreover, DA dynamics in rat brain were successfully monitored in real time, and the selective sensing ability of the microsensor in vivo was also demonstrated. The present study provides a new method for selective dynamics monitoring of DA in the brain, which would help to better understand the pathological and physiological functions of DA.