Hierarchical collagen fibers complexed with tannic acid and Fe3+ as a heterogeneous catalyst for enhancing sulfate radical-based advanced oxidation process

Development of an UV-Resistant Multilayer Film with Enhanced Compatibility between Carboxymethyl Cellulose and Polylactic Acid via Incorporation of Tannin and Ferric Chloride

Carboxymethyl cellulose (CMC) and polylactic acid (PLA) are recognized for their environmental friendliness. By merging them into a composite film, packaging solutions can be designed with good performance. Nonetheless, the inherent interface disparity between CMC and PLA poses a challenge, and there may be layer separation issues. This study introduces a straightforward approach to mitigate this challenge by incorporating tannin acid and ferric chloride in the fabrication of the CMC-PLA. The interlayer compatibility was improved by the in situ formation of a cohesive interface. The resulting CMC/TA-PLA/Fe multilayer film, devoid of any layer separation, exhibits exceptional mechanical strength, with a tensile strength exceeding 70 MPa, a high contact angle of 105°, and superior thermal stability. Furthermore, the CMC/TA-PLA/Fe film demonstrates remarkable efficacy in blocking ultraviolet light, effectively minimizing the discoloration of various wood surfaces exposed to UV aging.

Degradation of tetracycline by peroxymonosulfate activated with Mn0.85Fe2.15O4-CNTs: Key role of singlet oxygen

Tetracycline (TC) is a kind of electron-rich organic, and singlet oxygen (¹O₂) oxidative pathway-based advanced oxidation processes (AOPs) have represented outstanding selective degradation to such pollutants. In this paper, an excellent prepared strategy for ¹O₂ dominated catalyst was adopted. A catalyst composed of non-stoichiometric doping Mn-Fe bimetallic oxide supported on CNTs (0.3-Mn_0.85Fe_2.15O₄-CNTs) was synthesized and optimized by regulating the non-stoichiometric doping ratio of Mn & Fe and the loading amount of CNTs. Through optimization and control experiments, the optimized catalyst represented 94.9% of TC removal efficiency within 60 min in neutral condition under relatively low concentrations of Mn_0.85Fe_2.15O₄-CNTs (0.4 g/L) and PMS (0.8 mM). Through SEM and XRD characterization, Mn_0.85Fe_2.15O₄-CNTs was a hybrid of cubic Mn_0.85Fe_2.15O₄ uniformly dispersing on CNTs. By the characterization of XPS and FT-IR, more CO bonds and low-valent Mn (II) & Fe (II) appeared in Mn_0.85Fe_2.15O₄-CNTs. Reactive oxygen species (ROS) was determined by radical quenching experiments and electron spin resonance (EPR) spectroscopy, and ¹O₂ was verified to be the dominated ROS. The mechanism for PMS' activation was speculated, and more low-valent Mn (II) and Fe (II) contributed to the production of free-radical (•OH & SO₄^•-), while the reaction between PMS and the enhanced CO bond on Mn_0.85Fe_2.15O₄-CNTs played a crucial part in the generation of ¹O₂. In addition, through the comparative degradation of four different organics with distinct charge densities, the excellent selectivity of ¹O₂-based oxidative pathway to electron-rich pollutants was found. This paper supplied a good strategy to prepare catalyst for PMS activation to form a ¹O₂-dominated oxidative pathway.

Collagen and Silk Fibroin as Promising Candidates for Constructing Catalysts

A catalyst determines the mechanism of an organic chemical reaction, thus enabling the commercially viable formation of desired material products. Biopolymers offer new opportunities for the construction of catalysts by virtue of their biocompatibility, environmental benignity, and sustainability, as well as their low cost. Biopolymers are especially useful as carriers and precursors in catalysis application. The employment of biocompatible and biosustainable collagen and silk fibroin materials will revolutionize state-of-the-art electronic devices and systems that currently rely on conventional technologies. In this review, we first consider the ordered hierarchical structure, origin, and processing methods of collagen and silk fibroin. Then, the unique advantages and applicability of collagen and silk fibroin for constructing catalysts are summarized. Moreover, a summary of the state-of-the-art design, fabrication, and application of collagen- and silk fibroin-based catalysts, as well as the application of collagen- and silk-based catalysts, is presented by focusing on their roles as carriers and precursors, respectively. Finally, challenges and prospects are assessed for the construction and development of collagen and silk fibroin-based catalysts.

3D Porous Collagen Matrices-A Reservoir for In Vitro Simultaneous Release of Tannic Acid and Chlorhexidine

The treatment of wounds occurring accidentally or as a result of chronic diseases most frequently requires the use of appropriate dressings, mainly to ensure tissue regeneration/healing, at the same time as treating or preventing potential bacterial infections or superinfections. Collagen type I-based scaffolds in tandem with adequate antimicrobials can successfully fulfill these requirements. In this work, starting from the corresponding hydrogels, we prepared a series of freeze-dried atelocollagen type I-based matrices loaded with tannic acid (TA) and chlorhexidine digluconate (CHDG) as active agents with a broad spectrum of antimicrobial activity and also as crosslinkers for the collagen network. The primary aim of this study was to design an original and reliable algorithm to in vitro monitor and kinetically analyze the simultaneous release of TA and CHDG from the porous matrices into an aqueous solution of phosphate-buffered saline (PBS, pH 7.4, 37 °C) containing micellar carriers of a cationic surfactant (hexadecyltrimethylammonium bromide, HTAB) as a release environment that roughly mimics human extracellular fluids in living tissues. Around this central idea, a comprehensive investigation of the lyophilized matrices (morpho-structural characterization through FT-IR spectroscopy, scanning electron microscopy, swelling behavior, resistance against the collagenolytic action of collagenase type I) was carried out. The kinetic treatment of the release data displayed a preponderance of non-Fickian-Case II diffusion behavior, which led to a general anomalous transport mechanism for both TA and CHDG, irrespective of their concentrations. This is equivalent to saying that the release regime is not governed only by the gradient concentration of the releasing components inside and outside the matrix (like in ideal Fickian diffusion), but also, to a large extent, by the relaxation phenomena of the collagen network (determined, in turn, by its crosslinking degree induced by TA and CHDG) and the dynamic capacity of the HTAB micelles to solubilize the two antimicrobials. By controlling the degree of physical crosslinking of collagen with a proper content of TA and CHDG loaded in the matrix, a tunable, sustainable release profile can be obtained.

Polyphenol based hybrid nano-aggregates modified collagen fibers of biological valve leaflets to achieve enhanced mechanical, anticoagulation and anti-calcification properties

Glutaraldehyde (Glut)-crosslinked porcine pericardium and bovine pericardium are mainly consisted of collagen and widely used for the preparation of heterogenous bioprosthetic heart valves (BHV), which play an important role in the replacement therapy of severe valvular heart disease, while their durability is limited by degeneration due to calcification, thrombus, endothelialization difficulty and prosthetic valve endocarditis. Herein, we develop a novel BHV, namely, TPly-BP, based on natural tannic acid and polylysine to improve the durability of Glut crosslinked bovine pericardium (Glut-BP). Impressively, tannic acid and polylysine could form nanoaggregates via multiple hydrogen bonds and covalent bonds, and the introduction of nanoaggregates not only improved the mechanical properties and collagen stability but also endowed TPly-BP with good biocompatibility and hemocompatibility. Compared to Glut-BP, TPly-BP showed significantly reduced cytotoxicity, improved endothelial cell adhesion, a low hemolysis ratio and obviously reduced platelet adhesion. Importantly, TPly-BP exhibited great antibacterial and in vivo anti-calcification ability, which was expected to improve the in vivo durability of BHVs. These results suggested that TPly-BP would be a potential candidate for BHV.

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