A facile preparation of donut-like supramolecular tannic acid-Fe(III) composite as biomaterials with magnetic, conductive, and antioxidant properties

Photochemically Inert Broad-Spectrum Sunscreen by Metal-Phenolic Network Coatings of Titanium Oxide Nanoparticles

Titanium dioxide (TiO2) nanoparticles are extensively used as a sunscreen filter due to their long-active ultraviolet (UV)-blocking performance. However, their practical use is being challenged by high photochemical activities and limited absorption spectrum. Current solutions include the coating of TiO2 with synthetic polymers and formulating a sunscreen product with additional organic UV filters. Unfortunately, these approaches are no longer considered effective because of recent environmental and public health issues. Herein, TiO2-metal-phenolic network hybrid nanoparticles (TiO2-MPN NPs) are developed as the sole active ingredient for sunscreen products through photochemical suppression and absorption spectrum widening. The MPNs are generated by the complexation of tannic acid with multivalent metal ions, forming a robust coating shell. The TiO2-MPN hybridization extends the absorption region to the high-energy-visible (HEV) light range via a new ligand-to-metal charge transfer photoexcitation pathway, boosting both the sun protection factor and ultraviolet-A protection factor about 4-fold. The TiO2-MPN NPs suppressed the photoinduced reactive oxygen species by 99.9% for 6 h under simulated solar irradiation. Accordingly, they substantially alleviated UV- and HEV-induced cytotoxicity of fibroblasts. This work outlines a new tactic for the eco-friendly and biocompatible design of sunscreen agents by selectively inhibiting the photocatalytic activities of semiconductor nanoparticles while broadening their optical spectrum.

Effect of Low-Temperature Oxygen Plasma Treatment of Titanium Alloy Surface on Tannic Acid Coating Deposition

In this study, the effect of low-temperature oxygen plasma treatment with various powers of a titanium alloy surface on the structural and morphological properties of a substrate and the deposition of a tannic acid coating was investigated. The surface characteristics of the titanium alloy were evaluated by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle measurements. Following this, the tannic acid coatings were deposited on the titanium alloy substrates and the structural and morphological properties of the tannic acid coatings deposited were subject to characterization by XPS, SEM, and spectroscopic ellipsometry (SE) measurements. The results show that the low-temperature oxygen plasma treatment of titanium alloys leads to the formation of titanium dioxides that contain -OH groups on the surface being accompanied by a reduction in carbon, which imparts hydrophilicity to the titanium substrate, and the effect increases with the applied plasma power. The performed titanium alloy substrate modification translates into the quality of the deposited tannic acid coating standing out by higher uniformity of the coating, lower number of defects indicating delamination or incomplete bonding of the coating with the substrate, lower number of cracks, thinner cracks, and higher thickness of the tannic acid coatings compared to the non-treated titanium alloy substrate. A similar effect is observed as the applied plasma power increases.

High-Performance Material for the Effective Removal of Uranyl Ion from Solution: Computationally Supported Experimental Studies

Adsorption is a widely used method for pollution removal and for the recovery of valuable species. In recent years, the use of metal-organic compounds among the adsorbents used in adsorption studies has increased. In this study, the performance of the water-insoluble Fe complex as a metal organic framework (MOF-Fe-Ta) of water-soluble tannic acid, which is not used as an adsorbent in uranium recovery and removal, was investigated. For the characterization of the new synthesized material, Fourier transform infrared, scanning electron microscopy, and X-ray diffraction analyses were performed. The changes in the adsorption process based on various parameters were investigated and discussed. The point of zero charges value of the adsorbent was found as 5.52. It was noticed that the adsorption increases as the pH increases. Analyzing the effect of concentration on adsorption, we determined which model explained the adsorption better. The monolayer capacity of the adsorbent determined in light of the Langmuir model was reported as 0.347 mol kg^-1. The Freundlich constant, namely the β value obtained in the Freundlich model, which is a measure of surface heterogeneity, was found to be 0.434, and the E_DR value, which was found from the Dubinin-Raduskevich model and accepted as a measure of adsorption energy, was 10.3 kJ mol^-1. The adsorption was kinetically explained by the pseudo-second-order model and the adsorption rate constant was reported as 0.15 mol^-1 kg min^-1. The effect of temperature on adsorption was studied; it was emphasized that adsorption was energy consuming, that is, endothermic and ΔH was found as 7.56 kJ mol^-1. The entropy of adsorption was positive as 69.3 J mol^-1 K^-1. As expected, the Gibbs energy of adsorption was negative (-13.1 kJ mol^-1 at 25 °C), so adsorption was considered as a spontaneous process. Additionally, the power and mechanism of the interaction between studied adsorbent and adsorbate are explained through density functional theory computations. Computationally obtained data supported the experimental studies.

Delivery of amino acid oxidase via catalytic nanocapsules to enable effective tumor inhibition

Amino acids are the fundamental building blocks of proteins in tumor cells. The consumption of amino acid can be an effective approach for destroying the tumor cytoskeleton and malfunctioning of the intracellular metabolic balance. Following this concept, herein, amino acid oxidase (AAO) is delivered by hollow Fe3+/tannic acid nanocapsules (HFe-TA) and incorporated within the cancer cell membrane (M) for the first time for synergistic tumor therapy. In this system (M@AAO@HFe-TA), the intracellularly delivered AAO molecules catalyze the oxidative deamination effectively and consume amino acids significantly. The upregulation of intracellular acid and H2O2 concentration facilitates the HFe-TA mediated Fenton reaction and enhances the induction of cytotoxic ˙OH. With the combined effects, considerable in vitro and in vivo tumor inhibition was achieved by M@AAO@Fe-TA due to the activated Bcl-2/Bax/Cyt C/caspase 3 mitochondrial apoptotic pathway. This study offers an alternative therapeutic platform, functioning as a biomimetic cascade nanozyme, to enable synergistic starvation and chemodynamic tumor therapy with high efficacy.

Dynamic Mussel-Inspired Chitin Nanocomposite Hydrogels for Wearable Strain Sensors

It is an ongoing challenge to fabricate an electroconductive and tough hydrogel with autonomous self-healing and self-recovery (SELF) for wearable strain sensors. Current electroconductive hydrogels often show a trade-off between static crosslinks for mechanical strength and dynamic crosslinks for SELF properties. In this work, a facile procedure was developed to synthesize a dynamic electroconductive hydrogel with excellent SELF and mechanical properties from starch/polyacrylic acid (St/PAA) by simply loading ferric ions (Fe3+) and tannic acid-coated chitin nanofibers (TA-ChNFs) into the hydrogel network. Based on our findings, the highest toughness was observed for the 1 wt.% TA-ChNF-reinforced hydrogel (1.43 MJ/m3), which is 10.5-fold higher than the unreinforced counterpart. Moreover, the 1 wt.% TA-ChNF-reinforced hydrogel showed the highest resistance against crack propagation and a 96.5% healing efficiency after 40 min. Therefore, it was chosen as the optimized hydrogel to pursue the remaining experiments. Due to its unique SELF performance, network stability, superior mechanical, and self-adhesiveness properties, this hydrogel demonstrates potential for applications in self-wearable strain sensors.

Supramolecular Metallacycles and Their Binding of Fullerenes

The synthesis of a new triaminoguanidinium-based ligand with three tris-chelating [NNO]-binding pockets and C3 symmetry is described. The reaction of tris-(2-pyridinylene-N-oxide)triaminoguanidinium salts with zinc(II) formate leads to the formation of cyclic supramolecular coordination compounds which in solution bind fullerenes in their spherical cavities. The rapid encapsulation of C60 can be observed by NMR spectroscopy and single-crystal X-ray diffraction and is verified using computation.

Preparation of antimicrobial metallic nanoparticles with bioactive compounds

Despite the all recent advancements in medicine, infectious diseases continue to be major causes of death worldwide. Developing nanomaterials as preventive and therapeutic agents against infectious diseases has been one of the research priorities in medicine. However, the application of metal nanoparticles as antimicrobial agents is hampered due to environmental and safety concerns. Using green chemistry, researchers can produce biocompatible nanoparticles that have fewer detrimental effects on human health and the environment. Although chemical compounds have been considered as traditional sources for producing nanomaterials, a wide variety of biocompatible plant-derived secondary metabolites have recently been introduced that can be used to synthesize and stabilize metal nanoparticles. These metabolites have shown potent antibacterial effects making them suitable substitutes for the chemical agents in nanoparticle synthesis. This review has focused on the antimicrobial properties of metal nanoparticles synthesized using plant-derived secondary metabolites instead of crude extract. The mechanisms of metal nanoparticles synthesis and antimicrobial activity are also discussed for different phytochemicals and metal nanoparticles. Finally, the evaluation of the toxicity and safety of phytochemicals coated metal nanoparticles has been conducted. I believe that this is the first review on the antimicrobial and other biological properties of metal nanoparticles synthesized or coated utilizing specific plant-derived secondary metabolites.

Light and ferric ion responsive fluorochromic hydrogels with high strength and self-healing ability

Here, light and ferric ion (Fe³⁺) responsive fluorochromic hydrogels with high strength and self-healing ability were designed and synthesized.