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We describe herein the significance of a sodium citrate and tannic acid mixture in the synthesis of spherical silver nanoparticles (AgNPs). Monodisperse AgNPs were synthesized via reduction of silver nitrate using a mixture of two chemical agents: sodium citrate and tannic acid. The shape, size and size distribution of silver particles were determined by UV–Vis spectroscopy, dynamic light scattering (DLS) and scanning transmission electron microscopy (STEM). Special attention is given to understanding and experimentally confirming the exact role of the reagents (sodium citrate and tannic acid present in the reaction mixture) in AgNP synthesis. The oxidation and reduction potentials of silver, tannic acid and sodium citrate in their mixtures were determined using cyclic voltammetry. Possible structures of tannic acid and its adducts with citric acid were investigated in aqueous solution by performing computer simulations in conjunction with the semi-empirical PM7 method. The lowest energy structures found from the preliminary conformational search are shown, and the strength of the interaction between the two molecules was calculated. The compounds present on the surface of the AgNPs were identified using FT-IR spectroscopy, and the results are compared with the IR spectrum of tannic acid theoretically calculated using PM6 and PM7 methods. The obtained results clearly indicate that the combined use of sodium citrate and tannic acid produces monodisperse spherical AgNPs, as it allows control of the nucleation, growth and stabilization of the synthesis process. Graphical abstract ᅟ

The aim of the study was to improve the electrical and thermal conductivity of the polylactic acid/wood flour/thermoplastic polyurethane composites by Fused Deposition Modeling (FDM). The results showed that, when the addition amount of nano-graphite reached 25 pbw, the volume resistivity of the composites decreased to 108 Ω·m, which was a significant reduction, indicating that the conductive network was already formed. It also had good thermal conductivity, mechanical properties, and thermal stability. The adding of the redox graphene (rGO) combined with graphite into the composites, compared to the tannic acid-functionalized graphite or the multi-walled carbon nanotubes, can be an effective method to improve the performance of the biocomposites, because the resistivity reduced by one order magnitude and the thermal conductivity increased by 25.71%. Models printed by FDM illustrated that the composite filaments have a certain flexibility and can be printed onto paper or flexible baseplates.

Abstract Antibiotics are commonly overused to reduce weaning stress that leads to economic loss in swine production. As potential substitutes of antibiotics, plant extracts have attracted the attention of researchers. However, one of the plant extracts, tannic acid (TA), has an adverse effect on the growth performance, palatability, and intestinal absorption in weaning piglets when used at a large amount. Thus, this study aimed to investigate the effects of a proper dose of microencapsulated TA on the growth performance, organ and intestinal development, intestinal morphology, intestinal nutrient transporters, and colonic microbiota in weaning piglets. Forty-five Duroc × [Landrace × Yorkshire] (initial body weight = 5.99 ± 0.13 kg, weaned days = 21 d) piglets were randomly divided into five treatment groups (n = 9) and raised in 14 d. The piglets in the control group were raised on a basal diet; the piglets in the antibiotic test group were raised on a basal diet with three antibiotics (375 mg/kg Chlortetracycline 20%, 500 mg/kg Enramycin 4%, 1,500 mg/kg Oxytetracycline calcium 20%); and the other three groups were raised on a basal diet with three doses of microencapsulated TA (TA1, 500 mg/kg; TA2, 1,000 mg/kg; TA3, 1,500 mg/kg). All the piglets were raised in the same environment and given the same amount of nutrients for 2 wk. The results showed that both TA1 and TA2 groups had no adverse effect on the growth performance, organ weight and intestinal growth, and the pH value of gastrointestinal content. TA2 treatment improved the duodenal morphology (P < 0.05), increased the gene expression level of solute carrier family 6, member 19 and solute carrier family 15, member 1 (P < 0.05) in the ileum, and modulated the colonic bacteria composition (P < 0.05), but inhibited the activity of maltase in the ileum (P < 0.05) and the jejunal gene expression level of solute carrier family 5, member 1 (P < 0.05). In conclusion, our study suggests that a dosage between 500 and 1,000 mg/kg of microencapsulated TA is safe to be included in the swine diet and that 1,000 mg/kg of microencapsulated TA has beneficial effects on intestinal morphology, intestinal nutrient transporter, and intestinal microbiota in weaning piglets. These findings provide new insights into suitable alternatives to antibiotics for improving growth performance and colonic microbiota.

The interaction of Cu-tannic acid nanosheets (Cu-TA NShs) as nanozyme in a surfactant solution of CTAB under relatively acidic conditions is shown to exhibit a catalytic effect on quercetin (Qur). This catalytic property of Cu-TA NShs, which mimics laccase enzyme with many advantages, has been applied to developing a selective colorimetric sensor for the determination of trace amounts of Qur in vegetable samples. This strategy presents a desirable linear relationship between the absorbance signal intensity and the concentrations of Qur from 0.350 to 32.09 µM with a detection limit (LOD) of 0.064 µM (S/N = 3). The feasibility of the proposed portable colorimetric sensor for in situ analysis of the real samples has been validated with the high-performance liquid chromatography (HPLC) method as reference method, and two-tailed test ( t test) statistical analysis certifies good agreement between the results. This enzyme-free and sensitive naked-eye sensor with the smartphone-based color map is promising to provide technical support for the rapid and visual detection of Qur in vegetables. Graphical Abstract

Linear polyethyleneimine (L-PEI) was obtained from the acidic hydrolysis of poly(2-ethyl-2-oxazoline) and employed in the synthesis of physically crosslinked L-PEI hydrogel, PC-L-PEIH, chemically crosslinked L-PEI hydrogel, CC-L-PEIH, and cryogels, CC-L-PEIC. The preparation of L-PEI-based hydrogel networks was carried out in two ways: 1) by cooling the L-PEI solution from 90 °C to room temperature, and 2) by crosslinking L-PEI chains with a crosslinker, glycerol diglycidyl ether = 20 °C for CC-L-PEIC. Furthermore, a polyphenolic compound, tannic acid (TA), with superior antibacterial, antioxidant, and anti-inflammatory properties as an active biomedical functional agent, was encapsulated during the synthesis process within L-PEI-based hydrogels and cryogels, at 10% and 25% (w/w) based on the L-PEI amount. A linear and higher TA release was observed from physically crosslinked PEI-based hydrogels containing 10% and 25% TA-containing PC-L-PEI/TAH within 6 h, with 9.5 ± 05 mg/g and 60.2 ± 3.8 mg/g cumulative released amounts, respectively. A higher antioxidant activity was observed for 25% TA containing PC-L-PEI/TAH with 53.6 ± 5.3 µg/mL total phenol content and 0.48 ± 0.01 µmole Trolox equivalent/g. The minimum bactericidal concentration (MBC) of PC-L-PEIH and CC-L-PEIC networks against both E. coli (ATCC 8739) and Gram-positive B. subtilis (ATCC 6633) bacteria was determined at 5 mg/mL, whereas the MBC value of 10 mg/mL for CC-L-PEIH networks against the same bacteria was achieved.

Adhesives are widely used in daily life. However, during their preparation or application, traditional adhesives easily release toxic gases, which adversely affect the human body and the environment. Herein, a physically crosslinked tannic acid (TA)-based adhesive is prepared by forming hydrogen bonding between cellulose nanocrystals (CNCs), polyacrylamide (PAM), and TA. Different characteristics of the prepared adhesives, including morphology, water content, biocompatibility, curing time, and adhesion properties, were investigated. Lap shear strength of the adhesive depends on the water content and curing time, reaching a maximum at a curing time of 48 h. The addition of CNCs enhances the lap shear strength, with the adhesive sample with 6.0 g CNCs exhibiting a high lap shear strength of 5.5 MPa on wood, which is 34% higher than that of the PAM/TA adhesive. Moreover, TA-based adhesives have excellent biocompatibility. These CNC/PAM/TA adhesives have excellent potential for application in the furniture, construction, and building industries.

The enhancement method of modifying public filler (PF) with tannic acid (TA) for the preparation of modified fully recycled aggregate mortar (FRAM) was introduced in this research, aiming to improve its strength and durability and further enhance its application in construction. The improvement effect of TA on the microstructure and physical properties of public fine aggregate (PFA) at different concentrations and immersion times was analyzed. Besides, the physical properties and durability of FRAM were investigated and the strengthening mechanism of TA on FRAM was analyzed by micro-technical methods. The results revealed that the loose cement mortar on the surface of PFA could be removed after TA modification. TA could react with calcium hydroxide and calcite to generate nanoparticles in situ which promote cement hydration to improve the mechanical strength and durability of FRAM. Compared with the unmodified PFA, the compressive strength was increased by 24.62% at 28 d, and the capillary water absorption and electrical flux were reduced by 54.12% and 16.56%, respectively. Microscopic analysis further indicated that TA could improve the interfacial bonding effect of PFA, and enhance the cohesion of the hardened cementitious material, as well as that TA adsorbed on the surface of PFA could be dispersed to the freshly mixed cement mortar to improve the internal structure. The above results indicated that TA can significantly improve the performance of PFA, which has a positive effect on improving the mechanical strength and durability of FRAM and is conducive to saving natural aggregates (NA) and recycling construction resources.

Biobased plastics provide a sustainable alternative to conventional food packaging materials, thereby reducing the environmental impact. The present study investigated the effectiveness of chitosan with varying levels of Moringa oleifera seed powder (MOSP) and tannic acid (TA). Chitosan (CS) biocomposite films with tannic acid acted as a cross-linker, and Moringa oleifera seed powder served as reinforcement. To enhance food packaging and film performance, Moringa oleifera seed powder was introduced at various loadings of 1.0, 3.0, 5.0, and 10.0 wt.%. Fourier-transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy analyses were performed to study the structure and morphology of the CS/TA/MOSP films. The scanning electron microscopy results confirmed that chitosan/TA with 10.0 wt.% of MOSP produced a lightly miscible droplet/matrix structure. Furthermore, mechanical properties, swelling, water solubility, optical barrier, and water contact angle properties of the film were also calculated. With increasing Moringa oleifera seed powder contents, the biocomposite films’ antimicrobial and antifungal activity increased at the 10.0 wt.% MOSP level; all of the observed bacteria [Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Aspergillus niger (A. niger), and Candida albicans (C. albicans)] had a notably increased percentage of growth. The film, with 10.0 wt.% MOSP content, effectively preserves strawberries’ freshness, making it an ideal food packaging material.

The heterogeneous Fenton-like degradation overcome the shortage of traditional Fenton system, which got the high catalytic efficiency, good stability, wide pH working range, and so on. However, it is still challenging to develop highly efficient and recyclable solid catalysts in wastewater treatment. Herein, we employed melamine sponge (MS) as a base material to fabricate heterogeneous Fe/Cu-tannic acid (TA) coated MS (MS-Fe/Cu-TA) through the dip-coating method. The porous 3D structure of MS can enhance the catalyst loading, and expose more active catalytic sites to absorb dyes from solution. The loaded Fe/Cu weight ratio, pH value, H 2 O 2 dosage, and initial MB concentration on the catalytic activity were optimized to get highest methylene blue (MB) degradation efficiency. The MS survived five times of cyclic MB degradation, and degradation efficiency for other dyes (methyl orange, rhodamine B, malachite green) kept above 65%. This work brings potential insights for development of enhanced heterogeneous Fenton-like degradation for wastewater treatment. Graphical Abstract Herein, we employed melamine sponge (MS) as a base material to fabricate heterogeneous Fe/Cu-tannic acid (TA) coated MS (MS-Fe/Cu-TA) through the dip-coating method. The porous 3D structure of MS can enhance the catalyst loading, and expose more active catalytic sites to absorb dyes from solution. This work brings potential insights for development of enhanced heterogeneous Fenton-like degradation for wastewater treatment.

In this work, a new low-toxicity nanocontainer is proposed to functionalize an epoxy coating. The nanocontainer is made up of 1) a hierarchical mesoporous structure of ZnO, 2) the Mimosa tenuiflora [Mt] extract, and 3) a tannic acid-iron complex (Fe-TA). The performance of the modified coating with ZnO/[Mt]@Fe-TA nanocontainers sprayed on low-carbon steel in a saline solution of NaCl (3.5%) is evaluated. The characterization of the hierarchical mesoporous structure of ZnO includes the specific surface area and adsorption/desorption isotherms obtained by BET method. Likewise, the chemical composition of the extract of the [Mt] bark is determined by Fourier Transform Infrared Spectroscopy and 13 C Nuclear Magnetic Resonance. The nanocontainers are characterized by X-Ray Diffraction, Scanning Electronic Microscopy, Thermogravimetric Analysis, and Differential Scanning Calorimetry. The performance of the coating added with ZnO/[Mt]@Fe-TA nanocontainers is carried out by Electrochemical Impedance Spectroscopy (EIS). The results exhibit that although ionic permeability occurs in the coating, the ZnO/[Mt]@Fe-TA nanocontainers are responsible for the formation of an oxide layer that mitigates the degradation of the coating. In addition, the electrochemical parameters show oscillations throughout the entire exposure time, suggesting that ZnO/[Mt]@Fe-TA nanocontainers could be potential pigments for a self-healing coating.