Biomimetic structure of chitosan reinforced epoxy natural rubber with self-healed, recyclable and antimicrobial ability

Degradable biomedical elastomers: paving the future of tissue repair and regenerative medicine

Degradable biomedical elastomers (DBE), characterized by controlled biodegradability, excellent biocompatibility, tailored elasticity, and favorable network design and processability, have become indispensable in tissue repair. This review critically examines the recent advances of biodegradable elastomers for tissue repair, focusing mainly on degradation mechanisms and evaluation, synthesis and crosslinking methods, microstructure design, processing techniques, and tissue repair applications. The review explores the material composition and cross-linking methods of elastomers used in tissue repair, addressing chemistry-related challenges and structural design considerations. In addition, this review focuses on the processing methods of two- and three-dimensional structures of elastomers, and systematically discusses the contribution of processing methods such as solvent casting, electrostatic spinning, and three-/four-dimensional printing of DBE. Furthermore, we describe recent advances in tissue repair using DBE, and include advances achieved in regenerating different tissues, including nerves, tendons, muscle, cardiac, and bone, highlighting their efficacy and versatility. The review concludes by discussing the current challenges in material selection, biodegradation, bioactivation, and manufacturing in tissue repair, and suggests future research directions. This concise yet comprehensive analysis aims to provide valuable insights and technical guidance for advances in DBE for tissue engineering.

Amphiphilic nanofibrillated cellulose/polyurethane composites with antibacterial, antifouling and self-healing properties for potential catheter applications

This study focuses on enhancing interventional medical devices, specifically catheters, using a novel composite material. Challenges like corrosion and contamination in vivo, often caused by body fluids' pH, bacteria, and proteins, lead to mechanical damage, bacterial colonization, and biofilm formation on devices like catheters. The objective of this study was to prepare a versatile composite (HFs) by designing polyurethanes (HPU) with an ionic chain extender (HIID) and blending them with amphiphilic nanofibrillated cellulose (Am-CNF). The composite leverages dynamic interactions such as hydrogen bonding and electrostatic forces, as evidenced by Molecular Mechanics (MM) calculations. The H4F0.75 composite exhibited exceptional properties: 99 % length recovery post 600 stretching cycles at 100 % strain, rapid self-healing in artificial urine, high bactericidal activity, and excellent cell viability. Moreover, mechanical aging tests and UV-vis spectral analysis confirmed the material's durability and safety. These findings suggest that the HFs composite holds significant promise for improving catheters' performance in medical applications.

Cardiovascular diseases burden attributable to ambient PM2.5 pollution from 1990 to 2019: A systematic analysis for the global burden of disease study 2019

BACKGROUND

Ambient PM2.5 pollution (APMP2.5) was the leading environmental risk factor for cardiovascular diseases (CVDs) worldwide. An up-to-date comprehensive study is needed to provide global epidemiological patterns.

METHODS

Detailed data on CVDs burden attributable to APMP2.5 were obtained from the Global Burden of Disease Study (GBD) 2019. We calculated the estimated annual percentage change (EAPC) to assess temporal trends in age-standardized rates of deaths and disability-adjusted life years (DALYs) over 30 years.

RESULTS

Globally, CVDs attributable to APMP2.5 resulted in 2.48 million deaths and 60.91 million DALYs, with an increase of 122%, respectively from 1990 to 2019. In general, men suffered markedly higher burden than women, but the gap will likely turn narrow. As for age distribution, CVDs deaths and DALYs attributable to APMP2.5 mainly occurred in the elder group (>70 years). Low- and middle-income regions endured the higher CVDs burden due to the higher exposure to APMP2.5, and the gap may potentially expand further compared with high-income regions. For regions, the highest age-standardized rates of APMP2.5-related CVDs deaths and DALYs were observed mainly in Central Asia, while the lowest was observed in Australasia. At the national level, countries with the largest ASDR decline were clustered in western Europe, while Equatorial Guinea, Timor-Leste and Bhutan exhibited relatively rapid increases over this period.

CONCLUSIONS

The global CVDs burden attributable to APMP2.5 has contributed to the heterogeneity of spatial and temporal distribution. APMP2.5-related CVDs deaths have largely shifted from higher SDI regions to those with a lower SDI. Globally, APMP2.5-attributable CVDs pose a significant threat to public health and diseases burden has increased over time, particularly in male, old-aged populations. The governments and health systems should take measures to reduce air pollution to impede this rising trend.

Valorisation of Chitosan Natural Building Block as a Primary Strategy for the Development of Sustainable Fully Bio-Based Epoxy Resins

The non-toxic and biodegradable nature of chitosan makes it a valuable resource offering promising opportunities in the development of bio-based materials with enhanced mechanical and thermal properties. In this work, the combination of epoxidized linseed oil, oxalic or citric acids, and chitosan (CHI) as a curing accelerator presents an attractive strategy to create bio-based and sustainable thermosetting materials. This article aims to provide a comprehensive exploration of the systems reactivities, characteristics, and performance evaluation of the designed bio-thermosets. Both the nature of the two carboxylic acids and the presence of chitosan are shown to have a big impact on the thermomechanical properties of the developed networks. While oxalic acid favours the formation of elastic networks, with low Tg values (increasing with CHI content between 0.7 and 8.5 °C) and relatively low Young's modulus (~2.5 MPa), citric acid promotes the formation of very dense networks with lower mass of the segments between the crosslinks, having 20 times higher Tg values (from 36 to 45 °C) and ~161 times higher Young's modulus (from 94 MPa up to 404 MPa in these systems). The CHI has a strong impact on the curing reaction and on the overall properties, by increasing the materials' performance.

Design of epoxidized natural rubber/poly(lipoic acid) elastomer with fast and efficient self-healing under a mild temperature

Most of the dynamic covalent bonds (DCBs) for self-healing rubber must be activated at relatively high temperatures due to the requirement of high energy during the exchange of dynamic bonds, which may lead to unexpected degradation or excessive crosslinking of rubber. Herein, we designed and fabricated a highly stretchable, self-healable and reprocessable rubber by introducing dynamic disulfide bonds into the crosslink network of epoxidized natural rubber (ENR). Lipoic acid (LA) was firstly uniformly dispersed into ENR via a latex film formation technique, and then underwent a dynamic covalent ring-opening self-polymerization during hot pressing process, during which the carboxyl group of poly(LA) attacked the epoxy group of ENR to form β-hydroxyl ester bond crosslinks. As a result, a revisable covalently crosslinked network without rigid steric hindrance groups was constructed, which exhibited a super self-healing efficiency of 99 % after self-healing at 80 °C for only 3 h. The elongation at break of the elastomer could reach 1115 % and the recovery rate of reprocessing was as high as 91 %.

High content chitosan-based materials with high performance properties

Chitosan is a valuable biopolymer with a great potential to be used in the design of sustainable materials. Its use typically requires converting the solid powder into a quite dilute solution by disrupting the hydrogen bonding between primary amine and hydroxyl groups. In this work we show that chitosan can be reacted with a tris-aromatic tris-epoxy monomer, generating thermoset materials. The design of the new structures adopted a strategy where the chitosan was mixed in its solid form, to avoid the use of solvents and additional processing steps. A combined polymerization mechanism was proposed, including growth chain polymerization and polyaddition. The obtained materials containing different epoxy/chitosan weight percentage ratios show outstanding properties: high glass transition ~230 °C, high Young's modulus ~2116 and 1716 MPa, tensile strength of ~35 MPa and T_5% ~ 300 °C.

Electrophoretic Deposition of Biocompatible and Bioactive Hydroxyapatite-Based Coatings on Titanium

Current trends in biomaterials science address the issue of integrating artificial materials as orthopedic or dental implants with biological materials, e.g., patients' bone tissue. Problems arise due to the simple fact that any surface that promotes biointegration and facilitates osteointegration may also provide a good platform for the rapid growth of bacterial colonies. Infected implant surfaces easily lead to biofilm formation that poses a major healthcare concern since it could have destructive effects and ultimately endanger the patients' life. As of late, research has centered on designing coatings that would eliminate possible infection but neglected to aid bone mineralization. Other strategies yielded surfaces that could promote osseointegration but failed to prevent microbial susceptibility. Needless to say, in order to assure prolonged implant functionality, both coating functions are indispensable and should be addressed simultaneously. This review summarizes progress in designing multifunctional implant coatings that serve as carriers of antibacterial agents with the primary intention of inhibiting bacterial growth on the implant-tissue interface, while still promoting osseointegration.