Tetramethylpyrazine attenuates renal tubular epithelial cell ferroptosis in contrast-induced nephropathy by inhibiting transferrin receptor and intracellular reactive oxygen species.

Contrast-induced nephropathy (CIN) is a leading cause of hospital-acquired acute kidney injury (AKI). Recently, ferroptosis was reported to be crucial for AKI pathogenesis. Our previous studies indicated antioxidant tetramethylpyrazine (TMP) prevent CIN in vivo. However, whether ferroptosis is involved in TMP nephroprotective mechanism against CIN is unclear. In the present study, we investigated the role of renal tubular epithelial cell ferroptosis in TMP reno-protective effect against CIN and the molecular mechanisms by which TMP regulates ferroptosis. Classical contrast-medium, Iohexol, was used to construct CIN models in rats and HK-2 cells. Results showed that tubular cell injury was accompanied by ferroptosis both in vivo and in vitro, including the typical features of ferroptosis, Fe2+ accumulation, lipid peroxidation and decreased glutathione peroxidase 4 (GPX4). Ferroptosis inhibition by classic inhibitors Fer-1 and DFO promoted cell viability and reduced intracellular ROS production. Additionally, TMP significantly inhibited renal dysfunction, reduced AKI biomarkers, prevented ROS production, inhibited renal Fe2+ accumulation and increased GPX4 expression. Expressions of various proteins associated with iron ion metabolism, including transferrin receptor (TFRC), divalent metal transporter 1, iron-responsive element binding protein 2, ferritin heavy chain 1, ferroportin 1, and heat shock factor binding protein 1, were examined using mechanistic analyses. Among these, TFRC changes were the most significant after TMP pretreatment. Results of siRNA knockdown and plasmid overexpression of TFRC indicated that TFRC is essential for TMP to alleviate ferroptosis and reduce LDH release, Fe2+ accumulation and intracellular ROS. Our findings provide crucial insights about the potential of TMP in treating AKI associated with ferroptosis.

[Finite element method simulating bursting process of multi-chamber flexible package infusion bag].

This study aims to overcome the shortcomings such as low efficiency, high cost and difficult to carry out multi-parameter research, which limited the optimization of infusion bag configuration and manufacture technique by experiment method. We put forward a fluid cavity based finite element method, and it could be used to simulate the stress distribution and deformation process of infusion bag under external load. In this paper, numerical models of infusion bag with different sizes was built, and the fluid-solid coupling deformation process was calculated using the fluid cavity method in software ABAQUS subject to the same boundary conditions with the burst test. The peeling strength which was obtained from the peeling adhesion test was used as failure criterion. The calculated resultant force which makes the computed peeling stress reach the peeling strength was compared with experiment data, and the stress distribution was analyzed compared with the rupture process of burst test. The results showed that considering the errors caused by the difference of weak welding and eccentric load, the flow cavity based finite element method can accurately model the stress distribution and deformation process of infusion bag. It could be useful for the optimization of multi chamber infusion bag configuration and manufacture technique, leading to cost reduction and study efficiency improvement.

Aging forming process of Chlorella vulgaris growing medium and its cultivation inhibition mechanism.

To investigate the possibility of culture medium reuse in large-scale industrial microalgae cultivation for the alleviation of the massive water requirement pressure, the aging forming process of Chlorella vulgaris growing medium was explored and the aged medium's inhibition mechanisms on cell growth were inspected. The results demonstrated that when the medium was continuously reused, the collected maximal C. vulgaris biomass decreased. After the fourth medium reuse, the maximal biomass concentration was only 55 ± 1.1% of that in the fresh medium, which indicated the gradual aging of the medium. Furthermore, the composition variation of the released organic secretions during the culture medium reuse was monitored and the results showed that high concentrations of fatty acids (FAs), including palmitic acid, stearic acid, and small amounts of polysaccharides, were accumulated. Further investigation indicated that the obtained maximal biomass of C. vulgaris has a negative relationship with the manually added initial FA concentrations in the medium which suggested that the accumulated FAs in the medium probably were the main C. vulgaris growth inhibition factor. The inhibition effect of FAs on C. vulgaris was mainly achieved via impacting the cells' photosynthesis efficiencies to destroy the intracellular antioxidant system.

Wound-Healing Material with Antibacterial and Antioxidant Functions, Constructed Using Keratin, Hyperbranched Polymers, and MnO2.

Wound healing, a global medical issue, poses a substantial financial burden. Therefore, developing low-cost and highly efficacious wound-healing materials is essential. In this study, we prepared keratin-hyperbranched polymer hydrogel-M (KHBP-M), a multifunctional composite gel, by mixing reduced keratin containing free sulfhydryl groups extracted from human hair waste, hyperbranched polymer (HBP) with double bonds at the end, and MnO2 nanoparticles prepared using the biological template method. Keratin has intrinsic wound-healing properties, and MnO2 is a wound-healing material with both photothermal antibacterial and reactive oxygen species (ROS)-scavenging abilities. KHBP-M showed antibacterial effects against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. When exposed to irradiation (808 nm), the killing ratio for S. aureus reached 99.99%, which is especially suitable for wound environments. A similar trend was noted for E. coli. The composite hydrogel also showed excellent ROS-scavenging ability and could resist oxidative stress in L929 cells. Furthermore, in an animal model of infected wounds, the KHBP-M hydrogel treated with near-infrared light had the fastest wound-healing rate, reaching 82.98% on day 15. Our study provides a promising wound-healing material, with simple preparation methods, easy access to sources, and low cost involved.

Encapsulation of Imazalil in HKUST-1 with Versatile Antimicrobial Activity.

Based on high surface areas, adjustable porosity and microbicide activity, metal-organic frameworks (MOFs) HKUST-1 are widely used as drug release carriers for their slow degradation characteristics under slightly acidic conditions. In this work, porous HKUST-1 was reacted rapidly by cholinium salt (as the deprotonation agent and template) in an aqueous solution at room temperature. A novel antimicrobial system based on an imazalil encapsulated metal organic framework (imazalil IL-3@HKUST-1) was established. Imazalil IL-3@HKUST-1 could achieve synergism in inhibiting pathogenic fungi and bacteria. Moreover, six days after treatment, the slow and constant release of imazalil from imazalil IL@HKUST-1 exhibited better sustainability and microbicidal activity than imazalil. We believe that the method may provide a new strategy for related plant diseases caused by bacteria or fungi.

Corrigendum to "Polydopamine/poly(sulfobetaine methacrylate) Co-deposition coatings triggered by CuSO4/H2O2 on implants for improved surface hemocompatibility and antibacterial activity" [ Bioactive materials 6 (2021) 2546-2556].

[This corrects the article DOI: 10.1016/j.bioactmat.2021.01.025.].

pH-Activatable Organic Nanoparticles for Efficient Low-Temperature Photothermal Therapy of Ocular Bacterial Infection.

Low-temperature photothermal therapy (PTT) systems constructed by integrating organic photothermal agents with other bactericidal components that initiate bacterial apoptosis at low hyperthermia possess a promising prospect. However, these multicomponent low-temperature PTT nanoplatforms have drawbacks in terms of the tedious construction process, suboptimal synergy effect of diverse antibacterial therapies, and high laser dose needed, compromising their biosafety in ocular bacterial infection treatment. Herein, a mild PTT nanotherapeutic platform is formulated via the self-assembly of a pH-responsive phenothiazinium dye. These organic nanoparticles with photothermal conversion efficiency up to 84.5% necessitate only an ultralow light dose of 36 J/cm2 to achieve efficient low-temperature photothermal bacterial inhibition at pH 5.5 under 650 nm laser irradiation. In addition, this intelligent mild photothermal nanoplatform undergoes negative to positive charge reversion in acid biofilms, exhibiting good penetration and highly efficient elimination of drug-resistant E. coli biofilms under photoirradiation. Further in vivo animal tests demonstrated efficient bacterial elimination and inflammatory mitigation as well as superior biocompatibility and biosafety of the photothermal nanoparticles in ocular bacterial infection treatment. Overall, this efficient single-component mild PTT system featuring simple construction processes holds great potential for wide application and clinical transformation.

Polydopamine/poly(sulfobetaine methacrylate) Co-deposition coatings triggered by CuSO4/H2O2 on implants for improved surface hemocompatibility and antibacterial activity.

Implanted biomaterials such as medical catheters are prone to be adhered by proteins, platelets and bacteria due to their surface hydrophobicity characteristics, and then induce related infections and thrombosis. Hence, the development of a versatile strategy to endow surfaces with antibacterial and antifouling functions is particularly significant for blood-contacting materials. In this work, CuSO4/H2O2 was used to trigger polydopamine (PDA) and poly-(sulfobetaine methacrylate) (PSBMA) co-deposition process to endow polyurethane (PU) antibacterial and antifouling surface (PU/PDA(Cu)/PSBMA). The zwitterions contained in the PU/PDA(Cu)/PSBMA coating can significantly improve surface wettability to reduce protein adsorption, thereby improving its blood compatibility. In addition, the copper ions released from the metal-phenolic networks (MPNs) imparted them more than 90% antibacterial activity against E. coli and S. aureus. Notably, PU/PDA(Cu)/PSBMA also exhibits excellent performance in vivo mouse catheter-related infections models. Thus, the PU/PDA(Cu)/PSBMA has great application potential for developing multifunctional surface coatings for blood-contacting materials so as to improve antibacterial and anticoagulant properties.

pH-guided self-assembly of silver nanoclusters with aggregation-induced emission for rewritable fluorescent platform and white light emitting diode application.

Metal nanoclusters (NCs) as a new type of fluorescent material have attracted great interest due to their unique electronic structure and outstanding optical properties. However, limited success has been achieved in the preparation of water-soluble NCs with high luminous intensity. In this article, the significant luminescence properties of 4-mercaptobenzoic acid (H2mba)-capped Ag NCs induced by hydrochloric acid (HCl) through self-assembly strategies were reported and the water-soluble protonated silver nanoclusters (Ag-H-NCs) can be obtained. The original non-luminescent Ag NCs exhibit stable and bright luminescence resulting from aggregation-induced emission (AIE) by forming an ordered nanorod structure after assembly. Optical analysis allows for the establishment of relationships between ordered alignment and emission of Ag NCs components and it can be concluded that the ordered nanostructures are constructed by non-covalent interaction (hydrogen bond, π-π stacking, etc.) which effectively inhibits the intramolecular vibration and rotation of the ligand, thereby increasing the emission intensity of Ag NCs. Due to the outstanding optical behavior of the aqueous solution of Ag-H-NCs, it can be used as a rewritable fluorescent platform and a white light emitting diode (LED). The pH-guided strategy enriches the supramolecular self-assembly of novel noble metal NCs, which makes them a good candidate for optical materials.