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Poly(lactic acid) (PLA) is one of the most promising biopolymers extensively used in food, packaging, medical and pharmaceutical industries. It is due to favorable physicochemical properties, in-situ hydrolytic degradation and well-established processing parameters. However, in medical engineering applications, PLA shows some drawbacks like low cell adhesion, biological inertness, slow degradation rate and high acid inflammation. These shortcomings of pure PLA could be addressed by blending it with other bioresorbable materials and compatibilizers. This review provides comprehensive information on different PLA composites in the field of tissue engineering, implants, injury management and drug delivery systems. The PLA-based composites are divided into four parts: PLA/polymer, PLA/metal, PLA/ceramic, and PLA/nanoparticles. It also investigates various synthesis process, role of different compatibilizers, in vitro studies and their in vivo applications. Highlights * Review the trends of bioresorbable PLA blends/composites. * Extensively focused on PLA blend with polymer, metal, ceramic, and nanoparticles. * Role of reinforcement and compatibilizer to overcome shortcomings of PLA implant. * Highlights advantages, limitations, and properties of different types of PLA implants. * Discuss various clinical applications and future of PLA blends/composite scaffolds. KEYWORDS biomaterial, compatibilizer, PLA composite, PLA implants, PLA nanoparticles, 1 | INTRODUCTION A wide range of bioresorbable polymeric materials (BPM) has been investigated for biomedical engineering applications. The major advantage of BPM is to eliminate the need for a [...]

Bioresorbable polymeric stents (BPS) can become a promising alternative over permanent stents, as it reduce in-stent thrombosis, endothelial dysfunction, and thrombogenicity. Although, a few limitations like uncontrolled degradation, inadequate strength, and lack of radiopacity restrict its application. Thus, a novel bioresorbable radiopaque Mg-Zn-Y Alloy (BRM) of high effective atomic number ([Z.sub.eff]) was developed to reinforce and attenuate X-rays in the polymers. After that, the optimized BRM microparticles were blended with radiolucent poly (L-lactide)/poly ([epsilon]-caprolactone) (PLLA/PCL) polymer and extruded into biaxially expanded (BAE) tubes. Further, in this work, BAE tubes of PLLA/PCL/ BRM and PLLA/PCL were cut using the optimized Femtosecond laser machine (FSLM) parameters for fabricating cardiovascular stents. These stent materials were assessed to sustain the angioplasty procedure, such as radial strength, crimping, recoil, expansion process, and performance under cycling loading. Highlights * A novel biodegradable radiopaque Mg-Zn-Y alloy was developed. * Adding Mg alloy (5% wt.) in PLLA/PCL imparts X-ray visibility. * Composite stents show better compressive radial strength and flexibility. * It also reveals low crimping recoil, expansion recoil, and foreshortening. * Composite stents can withstand arterial vasomotion better than PLLA/PCL. KEYWORDS Biopolymer, Bioresorbable polymer, Composite stents, Crimping, Radiopacity, Recoil, 1 | INTRODUCTION Today, metallic stents are preferred due to their high impact strength, wear resistance, ductility, and toughness. (1) It demonstrates a high success rate in Percutaneous Coronary Intervention [...]

All bioresorbable polymeric implants are radiolucent, making them undetectable under the X-rays. Therefore, to improve their X-ray visibility, the high effective atomic number (Zeff) material such as Pt, Au, Ta, Ba, or its alloy are attached to the body of the bioresorbable implant. However, during the in vivo degradation, these bio-inert heavy metals can either detach or leach out from the lesion site and accumulate into the vital organ, leading to severe health complications. Thus, as a strategy, the novel biodegradable and radiopaque Mg alloy was produced to impart X-ray visibility in the biopolymer. Here, the Mg was alloyed with the optimized ratio of heavy metals, i.e., Zn and Y. The radiopaque Mg alloy was characterized and powdered to the size of 25–20 µm. Further, it was blended with radiolucent Poly-L-lactic acid (PLLA) and polycaprolactone (PCL) polymer. The Bi-axially expanded (BAE) tubes of PLLA/PCL and PLLA/PCL/Mg alloy (5% wt.) were extruded for fabricating cardiovascular stents. The BAE tube comparison studies were performed for thermal stability, wettability, surface roughness, and mechanical properties. The potential of 5% Mg alloy in the polymeric matrix was evaluated as a nucleating, reinforcing, and radiopaque agent. In vitro accelerated degradation study was performed in the physiological fluid to evaluate the pH variation and decomposition rate. Finally, in vitro biocompatibility was assessed by evaluating the behavior of L929 fibroblast cells, followed by the blood biocompatibility test on the blends. [ABSTRACT FROM AUTHOR]

A local Digital Volume Correlation (DVC) based measurement of displacements and strains of synthetic bone samples under an ex-situ compression using the time-lapsed imaging procedure was performed in the present study. Micro Finite Element (µFE) model was used to simulate the compression of synthetic bone samples with experimental-based (ExBC), and DVC interpolated displacement boundary conditions (IPBC). The obtained µFE nodal displacement data compared with DVC. A good match of displacement patterns and correlation values of R 2 = 0.85–0.99 and RMSE ≤ 12 µm was observed for the IPBC predicted displacements against DVC displacements. However, the ExBC provided a good correlation of transverse displacements only (U: R 2 = 0.85–0.99 and V: R 2 = 0.77–0.99). The average axial displacement of ExBC matched well with DVC, and a qualitative and quantitative understanding of the axial displacement was possible with ExBC. A moderate agreement of axial strain patterns was observed between DVC and IPBC, even though a good agreement on displacement was observed. The ExBC showed a higher axial strain compared to DVC in all samples. The transverse strains varied between the same extreme values for both boundary conditions and within the DVC range. [ABSTRACT FROM AUTHOR]

For the medical diagnosis, radiopaque materials (RM) made from high specific gravity elements like Pt, Au, Ta, Iodine, Bromine are either attached or blended or coated on an implant to makes it detectable under X-ray/Fluoroscopy/CT-Scan. RM facilitate the surgeon in an operation theatre to position an implant during the surgery. Mainly, RM are non-degradable, thus in case of biodegradable implants, it may detach from the body and accumulate in vital organ cause serious health issue. Therefore, a new bioresorbable radiopaque material (BRM) was produced by alloying the high specific gravity elements Zn (35% w/w) and Y(4% w/w) with Mg metal. In this alloy, three main phases were identified, alpha Mg, Mg 7 Zn 3 and icosahedral quasicrystalline I-phase Mg 3 Zn 6 Y, which reinforce the Mg matrix. Hereafter, BRM was powdered to a size of less than 25 microns and blended in different ratios with bioresorbable poly-L-lactic acid (PLLA) for fabricating PLLA/BRM bio-composite. BRM microparticles were uniformly distributed and interfacial bonded with the matrix. The X-ray was passed through bio-composite to capture µCT radiograph for evaluating linear attenuation co-efficient (µ) and optical density (OD). Thermal analysis reveals that BRM particles act as a nucleating site and enhance the crystallinity of the polymeric chain. During the In Vitro accelerated degradation study, the alkaline nature of BRM neutralise the acidity of PLLA and balance the pH of the body fluid to reduce the inflammatory reactions, but this compromises the stability of the polymer as it increases the decomposition rate. [ABSTRACT FROM AUTHOR]

An investigation of the effect of strain rate on the dynamic compressive behavior of glass/polytetrafluoroethylene (PTFE) composite is presented. Experimental studies were carried out on two dimensional (2D), satin weave (SW) and three dimensional (3D) woven glass/PTFE composites using split Hopkinson pressure bar (SHPB) apparatus. Commercial grades of glass/PTFE fabrics were autoclaved to prepare the composite laminates and circular specimens were cut out using a high‐pressure water jet. High strain rate studies confirmed the rate‐dependent behavior of all the woven composite systems under consideration. The highest rates of loading were attained by 3D woven specimens for identical incident energies. The highest peak stress attained by 3D woven specimens was 501 MPa, which was trailed by 2D woven specimens with 482 MPa stress. The advantage of satin weave was not reflected in the small specimens as the peak stress attained for identical loading was limited to 405 MPa. Similarly, the highest strain and toughness were recorded for 3D woven composites. However, the SW pattern unlocked a new possibility of controlling the primary damage axis. Furthermore, an analytical method is presented based on variable rate power law to predict the dynamic compressive stress of glass/PTFE. [ABSTRACT FROM AUTHOR]

A state of hypoxia (lack of oxygen) persists in the initial and later phases of healing in cardiovascular diseases, which can alter the tissue's repair or regeneration, ultimately affecting the structure and functionality of the related organ. Consequently, this results in a cascade of events, leading to metabolic stress and the production of reactive oxygen species (ROS) and autophagy. This unwanted situation not only limits the oxygen supply to the needy tissues but also creates an inflammatory state, limiting the exchange of nutrients and other supplements. Consequently, biomaterials have gained considerable attention to alleviate hypoxia and oxidative stress in cardiovascular diseases. Numerous oxygen releasing and antioxidant biomaterials have been developed and proven to alleviate hypoxia and oxidative stress. This review article summarizes the mechanisms involved in cardiovascular pathologies due to hypoxia and oxidative stress, as well as the treatment modalities currently in practice. The applications, benefits and possible shortcomings of these approaches have been discussed. Additionally, the review explores the role of novel biomaterials in combating the limitations of existing approaches, primarily focusing on the development of oxygen-releasing and antioxidant biomaterials for cardiac repair and regeneration. It also directs attention to various other potential applications with critical insights for further advancement in this area.