Presence Of Tannic Acid Research Articles

Tannic acid-reinforced soy protein/oxidized tragacanth gum-based multifunctional hemostatic film for regulation of wound healing

With recent advances in the field of tissue engineering, composite films with biocompatibility, antimicrobial properties, and wound healing properties have gained potential applications in the field of wound dressings. In this research work, composite films of soy protein (S)/oxidized tragacanth gum (G) were successfully made using the solution casting process. The metal-organic framework containing curcumin (MOF) with concentrations of 5 and 10 wt% and tannic acid (TA) with concentrations of 6 and 12 wt% were entered into the polymer film. Surface morphology with scanning electron microscope (FE-SEM), thermal stability, mechanical properties, chemical structure, antioxidant, water absorption, cell viability, antibacterial activity, and biodegradability of the prepared films were investigated in laboratory conditions. In addition, the toxicity of the films in the cell environment was investigated, and the results showed that cell growth and proliferation improved in the presence of the prepared films, especially films SG/MOF10/TA6 and SG/MOF10/TA12 due to the presence of TA and MOF containing curcumin. Also, the antibacterial activity of the films showed that the presence of tannic acid and curcumin in the structure of the films increases their ability against pathogens. According to the obtained results, the newly produced nanocomposite film (SG/MOF10/TA12) has a high potential to be used for wound dressing due to its favorable characteristics and was considered the optimal film.

Fabrication of Ag/Zr-SBA-15 materials in presence of tannic acid and their use in removal of organic pollutants from wastewater

Ag-, Zr- and AgZr- SBA-15 materials were synthesized in presence of tannic acid (TA) via hydrothermal method. They were used for removal of diclofenac (DCF), bisphenol A (BPA), tylosin tartrate (TYT) and methyl orange (MO) pollutants using adsorption and catalytic wet peroxide oxidation (CWPO) process. Low angle XRD patterns of all materials were consistent with the literature. Wide-angle XRD diffraction patterns exhibited peaks related with silver species but not related with zirconium species. However, XPS spectra showed presence of both silver (metallic/oxide forms) and zirconium (oxide forms) species. The highest surface area (638 m2/g), pore volume (1.22 cm3/g) and pore diameter (7.58 nm) values were obtained for Zr-SBA-15. TEM images showed that metals settled as nanoparticles within the silica matrix apart from Zr@SBA-15. FTIR spectra of the samples showed characteristic silicate bands of typical of silica-based materials. Ag-SBA-15 effectively inhibited the growth of all bacteria at concentrations ranging from 1000 to 250 μg/mL. In the presence only SBA-15 and peroxide, removal and conversion capacities of pollutant was very low. Silver containing materials exhibited superior efficiency in DCF removal (up to 87 %), while zirconium containing materials showed maximum removal efficiencies of 60 % for BPA and 68 % for TYT. Moreover, all materials displayed similar removal capacities for MO (up to 39 % with AgZr-SBA-15). Different kinetic models concurrently influenced the adsorption process. The highest catalytic conversion, achieving 91 % over 180 min, was observed with the Ag-SBA-15 material for DCF.

Aerogels of Polypyrrole/Tannic Acid with Nanofibrillated Cellulose for the Removal of Hexavalent Chromium Ions.

The preparation of conducting polymer aerogels is an effective strategy to produce innovative materials with enhanced physicochemical properties. Herein, polypyrrole (PPy) aerogels were oxidatively prepared in the presence of tannic acid (TA) with different concentrations (2.5, 5, and 10% mole ratio to pyrrole monomer) under freezing conditions. Nanofibrillated cellulose (NFC) was added during the PPy/TA synthesis to enhance mechanical stability. The effect of TA concentration on the aerogels' morphology, conductivity, thermal stability, and adsorption capacity was investigated. The conductivity of 9.6 ± 1.7 S cm-1 was achieved for PPy/TA prepared with 2.5% TA, which decreased to 0.07 ± 0.01 S cm-1 when 10% TA was used. PPy/TA aerogels have shown high efficacy in removing Cr(VI) ions from aqueous solutions. Adsorption experiments revealed that all the aerogels follow pseudo-second-order kinetics. PPy/TA prepared with NFC has a maximum adsorption capacity of 549.5 mg g-1.

The effect of knit structure on natural dyeing properties of cotton fabric

Natural dyeing of textile materials is gaining popularity all over the world since natural dyes are mostly eco-friendly, less toxic, and less allergenic as compared with synthetic dyes. Although synthetic dyes offer a broad range of color and color fastness and bright hues, they are nonbiodegradable and carcinogenic compounds and cause water pollution as well as waste disposal problems. This study presents the natural dyeing of cotton knitted fabric with three different structures using R. cordifolia root extract as a natural dye. Knitted fabrics with three different structures, interlock (350 g/m2), single jersey (145 g/m2) and rib (135 g/m2), were produced and dyed with madder (Rubia Cordifolia) in the presence of tannic acid as a mordant. The dyed samples were evaluated in terms of color measurement results (CIE L*,a*, b*, C*, h0, DE) and color fastness properties.

Z-scheme heterojunction engineering and hole-extraction layer enable efficient photoelectrochemical water splitting on BiVO4 photoanode

This study presents a novel Z-scheme heterostructure that was developed by integrating three-dimensional CoFe2O4 nanospheres with Mo and W co-doped BiVO4 (MW:BVO). Subsequently, ultra-thin hydroxides (NiOOH-FeOOH) were grown on the surface of the MW:BVO@CFO photoanode in the presence of tannic acid (TA), resulting in the formation of MW:BVO@CFO/TANF photoanodes. Notably, TANF served as a hole extraction layer. Compared to pristine MW:BVO, the photocurrent density of MW:BVO@CFO/TANF photoanodes exhibited a significant enhancement from 0.96 mA/cm2 to 6.03 mA/cm2 at 1.23 VRHE with a charge separation efficiency of 90.2 % due to the synergistic effect of the Z-scheme structure and hole extraction layer. Notably, the Z-scheme architecture facilitates the effective separation and transfer of electron-hole pairs, thereby retaining electrons and holes with high redox capacity. Meanwhile, the hole extraction layer quickly exports and aggregates the photo-generated holes, thereby further improving the separation efficiency of electron-hole pairs.

Development of Cross-Linked Gelatin Hydrogel Films Using Tannic Acid as Anti-Aging Active with Skin Care Potential

Hydrogel films based on gelatin, glutaraldehyde and glycerol are widely reported in many studies with applications focused on food packaging, microencapsulation and release of active drugs. Thus, this study used this composition to produce hydrogel films and brought as a novelty the incorporation of tannic acid (TA) as anti-aging active, due to its great antioxidant capacity. The presence of TA in the hydrogel films was verified by the C-O stretch absorption band at 1020 cm-1, as well as by its thermal degradation between 200 and 300 ºC. Furthermore, the presence of this active compound, which influenced the physical, morphological and mechanical properties of the film, was also confirmed by qualitative release tests. Additionally, the mechanical properties of the HT2 hydrogel film showed acceptable values of elongation at break (28.9 ± 3.1%) and Young modulus (6.4 ± 1.1 MPa), suggesting that this film has the potential to be applied in skin care routines.

Tannic acid promotes the activation of persulfate with Fe(ii) for highly efficient trichloroethylene removal.

Trichloroethylene (TCE) is an Environmental Protection Agency (EPA) priority pollutant that is difficult to be removed by some remediation methods. For instance, TCE removal using persulfate (PS) activated by ferrous iron (Fe(ii)) has been tested but is limited by the unstable Fe(ii) concentration and the initial pH of contaminated water samples. Here we reported a new TCE removal system, in which tannic acid (TA) promoted the activation of PS with Fe(ii) (TA-Fe(ii)-PS system). The effect of initial pH, temperature, and concentrations of PS, Fe(ii), TA, inorganic anions and humic acid on TCE removal was investigated. We found that the TA-Fe(ii)-PS system with 80 mg L-1 of TA, 1.5 mM of Fe(ii) and 15 mM of PS yielded about 96.2-99.1% TCE removal in the pH range of 1.5-11.0. Radical quenching experiments were performed to identify active species. Results showed that SO4˙- and ˙OH were primarily responsible for TCE removal in the TA-Fe(ii)-PS system. In the presence of TA, the Fe-TA chelation and the reduction of TA could regulate Fe(ii) concentration and activate persulfate for continuously releasing reactive species under alkaline conditions. Based on the excellent removal performance for TCE, the TA-Fe(ii)-PS system becomes a promising candidate for controlling TCE in groundwater.

Polyphenol modification of graphene-stabilized emulsions to form electrically conductive polymer spheres

HypothesisPolyphenols, specifically tannic acid, should increase the hydrophilicity of graphene when added during the interfacial exfoliation through π-π stacking. Following Bancroft’s rule, increasing the hydrophilicity of graphene will result in a phase inversion of water-in-oil emulsions stabilized by graphene. Polymerization of the oil phase will then lead to graphene-coated spheres rather than graphene-stabilized polyHIPEs. ExperimentsOptical particle sizing, microscopy, contact angle, and electrical conductivity measurements were performed to determine the mechanism of sphere formation in graphene-stabilized emulsions modified with tannic acid. Studies focused on the effect of graphite flake size, graphite concentration, tannic acid concentration, and oil phase composition. Particle sizing and scanning electron microscopy examined the spheres' size, shape, and surface morphology. Contact angle measurements gave insight into the change in graphene surface energy. Conductivity studies examined the graphene shell surrounding the spheres. FindingsAdding tannic acid to graphene-stabilized emulsions induced a phase change from water-in-oil to oil-in-water. Contact angle measurements confirmed greater hydrophilicity of graphene in the presence of tannic acid. However, very high tannic acid concentrations led to a decrease in the stability of the emulsion. Varying the graphite flake size and concentration resulted in morphology and conductivity changes. Dilution of the monomer phase produced hollow microcapsules.

Dual network zwitterionic hydrogels with excellent mechanical properties, anti-swelling, and shape memory behaviors

In this study, a conductive double network cross-linked hydrogel with anti-swelling and shape memory was successfully prepared by [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA), polyvinyl alcohol (PVA), and tannic acid (TA). The hydrogel is formed by SBMA radical polymerization to form the first layer of the network and PVA freeze-thawing to form the second layer of the network. The conversion of -SO3- on the SBMA structure to -SO3H in the presence of TA and the electrostatic repulsion between -N+(CH3)3 reduces the osmotic pressure and achieves an anti-swelling effect. The prepared hydrogels have good mechanical properties tensile strength of 1.4 MPa, elongation at break of 287.52 %, and compressive strength of 2.36 MPa at 80 % strain. The structure of SBMA forms ion channels with stable conductivity, simulating the realization of underwater monitoring movements. In addition, the hydrogel can recover its original shape in a few seconds at 60 °C and has a 99 % inactivation rate against E. coli and S. aureus within 24 h, which can provide new ideas for the biomedical field.

Design of a novel tannic acid enriched hemostatic wound dressing based on electrospun polyamide-6/hydroxyethyl cellulose nanofibers

Recently, the use of scaffolds as wound dressings in skin tissue engineering with the aim of rapid healing and prevention of bleeding is growing quickly, materials and structures similar to the target tissue are used to improve its quality. In this research, polyamide6/hydroxyethyl cellulose (PA6/HEC) incorporated with TA (tannic acid) in different concentration (5, 10, 25%) has been used to produce nanofibers (NFs) by electrospinning method. Electrospun NFs were examined in terms of chemical and physical structure, swelling, degradation, moisture retention, thermal stability and mechanical properties. In addition, this study investigates cellular behavior, antibacterial, hemocompatibility and antioxidant properties. Among the NFs, PA/HEC/25%TA mat showed more favorable results. The produced scaffolds were non-toxic in the cell media, and increasing TA content improved cell growth and proliferation. The results of the hemostatic test showed that the presence of TA causes rapid blood coagulation, and TA has increased the antibacterial ability against pathogenic agents and antioxidant virtues. Therefore, the obtained results confirm the potential of NFs as a wound dressing.

Glutathione-Responsive Tannic Acid-Assisted FRET Nanomedicine for Cancer Therapy.

In cancer combination therapy, a multimodal delivery vector is used to improve the bioavailability of multiple anti-cancer hydrophobic drugs. Further, targeted delivery of therapeutics along with simultaneous monitoring of the drug release at the tumor site without normal organ toxicity is an emerging and effective strategy for cancer treatment. However, the lack of a smart nano-delivery system limits the application of this therapeutic strategy. To overcome this issue, a PEGylated dual drug, conjugated amphiphilic polymer (CPT-S-S-PEG-CUR), has been successfully synthesized by conjugating two hydrophobic fluorescent anti-cancer drugs, curcumin (CUR) and camptothecin (CPT), through an ester and a redox-sensitive disulfide (-S-S-) linkage, respectively, with a PEG chain via in situ two-step reactions. CPT-S-S-PEG-CUR is spontaneously self-assembled in the presence of tannic acid (TA, a physical crosslinker) into anionic, comparatively smaller-sized (~100 nm), stable nano-assemblies in water in comparison to only polymer due to stronger H-bond formation between polymer and TA. Further, due to the spectral overlap between CPT and CUR and a stable, smaller nano-assembly formation by the pro-drug polymer in water in presence of TA, a successful Fluorescence Resonance Energy Transfer (FRET) signal was generated between the conjugated CPT (FRET donor) and conjugated CUR (FRET acceptor). Interestingly, these stable nano-assemblies showed a preferential breakdown and release of CPT in a tumor-relevant redox environment (in the presence of 50 mM glutathione), leading to the disappearance of the FRET signal. These nano-assemblies exhibited a successful cellular uptake by the cancer cells and an enhanced antiproliferative effect in comparison to the individual drugs in cancer cells (AsPC1 and SW480). Such promising in vitro results with a novel redox-responsive, dual-drug conjugated, FRET pair-based nanosized multimodal delivery vector can be highly useful as an advanced theranostic system towards effective cancer treatment.

Zinc-Based Tannin-Modified Composite Microparticulate Scaffolds with Balanced Antimicrobial Activity and Osteogenesis for Infected Bone Defect Repair.

Treatment of infected bone defects is a major clinical challenge; bioactive materials combining sufficient antimicrobial activity and favorable osteogenic ability are urgently needed. In this study, through a facile one-pot hydrothermal reaction of zinc acetate in the presence of tannic acid (TA), with or without silver nitrate (AgNO3 ), is used to synthesize a TA or TA and silver nanoparticles (Ag NPs) bulk-modified zinc oxide (ZnO) (ZnO-TA or ZnO-TA-Ag), which is further composited with zein to fabricate porous microparticulate scaffolds for infected bone defect repair. Bulk TA modification significantly improves the release rate of antibacterial metal ions (Zn2+ release rate is >100 times that of ZnO). Fast and long-lasting (>35 d) Zn2+ and Ag+ release guaranteed sufficient antibacterial capability and excellent osteogenic properties in promoting the osteogenic differentiation of bone marrow mesenchymal stem cells and endogenous citric acid production and mineralization and providing considerable immunomodulatory activity in promoting M2 polarization of macrophages. At the same time, synchronously-released TA could scavenge endogenous reactive oxygen species (ROS) and ROS produced by antibacterial metal ions, effectively balancing antibacterial activity and osteogenesis to sufficiently control infection while protecting the surrounding tissue from damage, thus effectively promoting infected bone defect repair.

Adsorption of 17α-methyltestosterone onto silica-based porous materials: Effect of porosity and functionalization, reversible kinetics, and the coexistence of tannic acid

This study investigated the impacts of porosity and the surface functional groups of silica-based porous materials on the adsorption of 17α-methyltestosterone (MT) in low concentration ranges (μg L−1), including the role of coexisting tannic acid (TA). The reversible adsorption kinetics of MT revealed that it was preferentially adsorbed by the mesoporous cylindrical pores of Santa Barbara Amorphous-15 (SBA-15) rather than by the wormhole-like pores of hexagonal mesoporous silica and the micropores of NaY. Furthermore, the increasing pore diameter of SBA-15 from 5.8 nm to 19.9 nm (SBA-CHX) could inhibit reverse desorption and maintain the accessibility of MT through the internal surface area. Due to its high hydrophobicity, the grafted triethoxyoctyl- group had an influential role in hydrophobic partitioning, enhancing the adsorption of MT, especially when grafted on the extended pores of SBA-CHX. The adsorption mechanisms of MT on silica-based adsorbents might involve hydrophobic partitioning, π–π interaction, hydrogen bonding, and ion-dipole interaction. The presence of TA could enhance the selective adsorption of MT onto hydrophobic functionalized SBA-15 s via the increase of hydrophobic partitioning. In conclusion, the large pore diameter of SBA-15 (above 5.8 nm) and grafting with the triethoxyoctyl- group could provide the highest MT adsorption capacity and effectively reject the coexisting TA.

Tannic acid-assisted in-situ interfacial formation of Prussian blue-assembled adsorptive membranes for radioactive cesium removal.

There is a growing interest in advanced materials that can effectively treat wastewater contaminated with radioactive cesium (137Cs), which is an extremely hazardous material. Here, we report a new class of Cs-adsorptive membranes compactly assembled with Cs-adsorptive Prussian blue (PB) particles. The PB particle assembly was formed via an in-situ interfacial reaction between two PB precursors in the presence of tannic acid (TA) as a binder on a porous support. While the interfacial reaction enabled the formation of a defect-less PB network, TA enhanced the PB-PB and PB-support compatibilities, consequently producing a uniform, densely packed PB assembly near the support surface. The fabricated TA-assisted PB membrane (PB/TA-M) synergistically rejected Cs via a combination of adsorption and membrane filtration, although adsorption predominantly determined Cs rejection initially. Hence, the PB/TA-M membrane showed considerably higher Cs removal performance than commercial nanofiltration (NF) and reverse osmosis (RO) polyamide (PA) membranes for a sufficiently long operation time. Furthermore, the PB/TA-M membrane displayed excellent radioactive 137Cs removal performance, significantly exceeding those of commercial NF and RO PA membranes due to its higher radiation stability, indicating its viability for application in treating actual radioactive wastewater.

Active Packaging Film Based on Poly Lactide-Poly (Butylene Adipate-Co-Terephthalate) Blends Incorporated with Tannic Acid and Gallic Acid for the Prolonged Shelf Life of Cherry Tomato

The antimicrobial property is the key feature of active packaging. Biological macromolecules such as tannic and gallic acids are naturally found in plants such as tea, fruits, berries, and grapes. The incorporation of tannic acid (TA) and gallic acid (GA) in the biodegradable polymer blend Poly Lactide-Poly (Butylene Adipate-Co-Terephthalate) (PLA-PBAT) was used in this study to assess the potential of active packaging. TA and GA (10 wt%) composite films showed a 65%–66% increase in the UV barrier property. The tensile strength value increased after the incorporation of TA and GA (10 wt%), respectively. Overall, 1.67 and 2.2 log reductions in E. coli and L. monocytogenes growth were observed, respectively, in the presence of TA (10 wt%) composite film. In addition, TA composite film was able to maintain and enhance the quality of cherry tomatoes for up to 20 days of storage at room temperature. For cherry tomatoes packed in PLA-PBAT-TA10 (wt%), TSS decreased by 6.3%, pH was 4.3, and a microbial reduction of 2.70 log CFU/mL was observed. In conclusion, TA composite film had confirmed significant UV blocking properties, surface hydrophobicity, and antibacterial properties, which show its potential as an active packaging film.

Effects of particle size on the adsorption behavior and antifouling performance of magnetic resins.

Adequately choosing the physicochemical characteristics of adsorbent is crucial in improving its adsorption performance. This work investigated the effect of particle size of magnetic resins on adsorption behaviors of tetracycline (TC) and their antifouling performance. Smaller particle size resin Q150 (10-30 μm) shows notably faster TC adsorption kinetics when compared resins with hundreds of microns (Q100 and Q1). Simulated by Weber-Morris equation, the film diffusion time of Q150 was only 20 min, 2-25 times faster than that of other resins. At this adsorption time, Q150 can reach more than 80% of the maximum adsorption, and the ring-like fluorescence images indicate that the molecules are accumulated on the external surface. Q150 also shows better reusability and antifouling performance over Q100 and Q1. After 20 adsorption-desorption cycles, the adsorption capacity of Q150 at 20 min only decreases 9.7%. The presence of tannic acid also only slightly decreases the adsorption capacity. The faster adsorption kinetics and the superior antifouling performance of Q150 make it a promising adsorbent in future use.

Comparing the influence of humic/fulvic acid and tannic acid on Cr(VI) adsorption onto polystyrene microplastics: Evidence for the formation of Cr(OH)3 colloids

Microplastics (MPs) can act as vectors for various contaminants in the aquatic environment. Although some research has investigated the adsorption characteristics and influencing factors of metals/organic molecules on MPs, the effects of dissolved organic matter (DOM) (which are ubiquitous active species in ecosystems) on metal oxyanions such as Cr(VI) capture by MPs are largely unknown. This study explored the adsorption behaviors and mechanisms of Cr(VI) oxyanions onto polystyrene (PS) MPs using batch adsorption experiments and multiple spectroscopic methods. The effects of representative DOM components (i.e., humic acid (HA), fulvic acid (FA) and tannic acid (TA)) on Cr(VI) capture by PS were particularly studied. Results revealed a significantly enhanced adsorption of Cr(VI) on PS in the presence of TA. The Cr(VI) adsorption capacity was increased from 2876 μg g−1 to 4259 μg g−1 and 5135 μg g−1 when the TA concentrations raised from 0 to 10 and 20 mg L−1, respectively. Combined microscopic and spectroscopic investigations revealed that Cr(VI) was reduced to Cr(III) by TA and formed stable Cr(OH)3 colloids on PS surfaces. Contrarily, HA and FA inhibited Cr(VI) adsorption onto PS, especially at pH > 2.0 and higher DOM concentrations, due to site competition and electrostatic repulsion. Increase in pH was found to reduce zeta potentials of MPs, resulting in inhibited Cr(VI) adsorption. The adsorbed Cr(VI) declined with increasing ionic strength, implying that outer-sphere surface complexation affected the adsorption process in the presence of DOM. These new findings improved our fundamental understanding of the fate of Cr(VI) and MPs in DOM-rich environmental matrices.

Formulation and characterization of microcapsules encapsulating carvacrol using complex coacervation crosslinked with tannic acid

Carvacrol-loaded microcapsules were developed based on coacervation complexes of whey protein isolate (WPI) and high methoxyl pectin (HMP), followed by cross-linking with tannic acid (TA). Optimal pH and WPI-HMP ratios for complex coacervation were found to be 4.1 and 5:1, respectively. Coacervation complexes were used to encapsulate carvacrol. Optimum conditions for achieving morphology and encapsulation efficiency were found for wall materials with a concentration of 2% (w/v), a wall/core ratio of 1:2 (w: w), and a homogenization speed of 15,000 rpm. The optimized formulation of microcapsules has an encapsulation efficiency of 77.48 ± 0.03% for carvacrol and a size of 1.08 μm. The addition of tannic acid (TA) decreased particle size and had no other influence on the morphological properties of microcapsules. Additionally, Fourier transform infrared spectroscopy (FTIR) indicated that coacervates were formed through the electrostatic interactions between WPI and HMP and the main force between TA and coacervates is hydrogen bonding. The addition of HMP to WPI and the presence of TA both decreased the content of tryptophan residues. Carvacrol microcapsules crosslinked with TA demonstrated better stability and antioxidant properties, showing potential for encapsulation of bioactive substances.

The physical and optical investigations of the tannic acid functionalised Cu-based oxide nanostructures

The need for a mild, low-cost, green environment that is able to produce exotic properties of output nanostructures is appealing nowadays. Employing these requirements, the copper (Cu)—based oxide nanostructures have been successfully synthesised via one-pot reaction using biocompatible natural polyphenol, tannic acid (TA) as both the reducing agent and stabiliser at 60, 70 and 80 °C. The structural and optical studies disclosed the effect of TA on the surface morphology, phase purity, elemental composition, optical microstrain and optical intrinsic energy of this mixed Cu2O and CuO nanostructures. The optically based method describes the comparative details of the multi-band gap in the presence of more than one element with overlapping spectra from the first-derivative absorbance curve frac{Delta E}{Delta A} and the exponential absorbance of Urbach tail energy {E}_{U} towards the conventional Tauc bandgap. The frac{Delta E}{Delta A} demonstrates that the pronounced effect of TA that Cu2O and CuO nanostructures creates much sensitive first-derivative bandgap output compared to the Tauc bandgap. The results also show that the {E}_{U} reduced as the temperature reaches 70 °C and then experienced sudden increase at 80 °C. The change in the pattern is parallel to the trend observed in the Williamson–Hall microstrain and is evident from the variations of the mean crystallite size {D}_{m} which is also a cause response to the change in temperature or pH. Therefore, the current work has elucidated that the structural and optical correlations on the as-synthesised Cu2O and CuO nanostructures in the presence of TA were the combined reaction of pH change and the ligand complexation reactions. The acquired results suggest a more comprehensive range of studies to further understand the extent relationship between the physical and optical properties of TA functionalised Cu-based oxide nanostructures.

α-Amylase Changed the Catalytic Behaviors of Amyloglucosidase Regarding Starch Digestion Both in the Absence and Presence of Tannic Acid

The courses of starch digestion with individual α-amylase (AA), amyloglucosidase (AMG), and AA/AMG bi-enzyme system were performed and analyzed by first-order-reaction equations in the absence and presence of tannic acid (TA). An antagonistic effect between AA and AMG occurred at the digestion phase of readily-digestible starch due to the higher catalytic efficiency of AMG for starchy-substrates with more complex structures. This effect caused a faster rate of glucose production with AMG than with AA/AMG bi-enzyme system at this phase both in the absence and presence of TA. TA had a higher binding affinity to AA than to AMG as accessed by several methods, such as inhibition kinetics, fluorescence quenching, isothermal titration calorimetry (ITC), and molecular docking. Besides, differential scanning calorimetry (DSC) indicated that the change in the thermal and structural stabilities of enzymes in the presence of TA was related to the enzyme residues involved in binding with TA, rather than the inhibitory effects of TA. The binding characters of TA to both enzymes resulted in more “free” AMG without TA binding in AA/AMG bi-enzyme system than that in individual AMG. This binding property caused more and faster rate of glucose production at the digestion phase of slowly digestible starch (SDS) in the bi-enzyme system.