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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 [...]

Voice prostheses are known to fail in few weeks to several months of implantation due to the clogging mainly caused by microbial biofilm formation, which is a cause of concern. Iodine is a known broad-spectrum biocide and is reported to easily form complexes with various polymers. For long term device disinfection, strong iodine complexation that offers sustained iodine release for a prolonged period is essential. The present research work deals with the synthesis of a poly(methyl methacrylate-n-butyl acrylate-N-vinyl-2-pyrrolidone) (poly[MMA-BA-NVP]) tercopolymer through free radical polymerization for surface coating thermoplastic polyurethane (TPU) based voice prostheses. The NVP content in the tercopolymer was varied from 20% to 50% to optimise iodine loading and subsequent release. Base TPU coated with the tercopolymer was treated with 4% aqueous iodine solution at room temperature (28 ± 3 °C) for two hours. It was observed that the tercopolymer containing 35% N-vinyl-2-pyrrolidone (NVP), 32.5% methyl methacrylate (MMA) and 32.5% butyl acrylate (nBA) gave a stable coating on TPUs together with sustained iodine release for a prolonged period. Furthermore, the tercopolymer coated and iodine loaded TPUs exhibited excellent antimicrobial activity against Candida albicans, Staphylococcus aureus and Escherichia coli. [ABSTRACT FROM AUTHOR]

In the present research, glass and basalt fiber-reinforced polypropylene composites' behaviour in quasi-static and dynamic conditions is studied. Composites were fabricated by vacuum assisted Compression molding method. Composites failure under quasi-static tension and compressive conditions was studied along with its failure behaviour under low-velocity impact and super-sonic shock loading under dynamic conditions. The study results showed that basalt fiber-reinforced polypropylene (Basalt/PP) composite's tensile and compressive strength is higher than glass fiber-reinforced polypropylene (Glass/PP). The Basalt/PP showed no penetration against low velocity impact (LVI) with negligible deformations till 50 J. However, the Glass/PP perforated at 50 J with various failure patterns occurring at back side. The fiber-matrix interface adhesion plays an important role in super-sonic shock loading by absorbing shock wave energy due to ductile nature of polypropylene and the two composites absorbed energy via matrix and fibers failure, no brittle failure of laminates occurred under shock loading. [ABSTRACT FROM AUTHOR]

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]

In this study, the mechanical performance of electrospun ultra‐high molecular weight polyethylene (UHMWPE) fiber was successfully improved by post‐processing treatment. It is performed by stretching the electrospun UHMWPE mat under constant load at temperatures ranging from 90 to 150°C. The temperature is varied in order to achieve the highest possible draw ratio. The prepared fibers were characterized for their morphological and thermal properties. Moreover, the induced fiber morphology and their performance due to the effect of high‐temperature stretching were evaluated using different characterization techniques such as scanning electron microscopy, wide‐angle X‐ray diffraction, and tensile testing analysis. In addition, the characteristics of prepared yarns were also compared with a commercial grade of Spectra® fibers. This analysis shows that the post‐processing of the mat resulted in the production of axially elongated microfibrillar yarn. Maximum tensile strength of 11.14 ± 3.65 GPa was attained at a stretching temperature of 130°C. However, further raising the temperature causes a decline in performance, demonstrating that the stretching temperature dramatically influences the properties of the fiber. [ABSTRACT FROM AUTHOR]

Compressive behaviour of open and closed cell polyurethane foam samples under large deformation is studied using micro‐Computed Tomography (micro‐CT), Digital Volume Correlation (DVC) technique and micro‐Finite Element (micro‐FE) modelling. The micro‐CT images of the foam samples at different compression strains are used to determine anisotropy in the foams, to obtain qualitative information on deformation mechanisms, to quantify the deformation and strains using a local DVC approach and to generate images for micro‐FE modelling of the foam samples. Micro‐FE modelling predicts the deformation using an elastoplastic material model coupled with continuum damage mechanics. Two different types of boundary conditions, experimentally derived (ExBC) and interpolated from DVC (IPBC), were implemented to evaluate the displacements in the micro‐FE models. A reduced integration scheme in micro‐FE analysis resulted in high artificial energy and was discarded in favour of full integration. The displacement predicted by IPBC matched with DVC displacement contours for closed cell foam. The ExBC‐predicted axial displacement (W) showed a better agreement with DVC than transverse displacements (U, V) contours. However, a significant statistical comparison (R2 > 0.70) of all displacements was obtained for both IPBC and ExBC. For open cell foam, both boundary conditions predicted a significant difference in the displacement contours with respect to DVC measurements. Still, the axial displacements of ExBC and IPBC showed a better statistical significance (R2 > 0.70). [ABSTRACT FROM AUTHOR]

Despite its relevance for law enforcement applications, the design of soft armor has mainly been based on a trial-and-error approach. In this paper, a combined experimental, machine learning, and finite element analysis framework is used to build a predictive numerical model for the analysis and hence, design of soft armor. The material models for major components of the soft armor certification system--bullet, shoot pack, straps, and clay backing, are first constructed using laboratory tests and publicly available data. Next, three metrics, namely, back face signature (BFS), number of penetrated shoot-pack layers, and mushrooming of the bullet are established to gauge the model's accuracy with respect to the laboratory ballistic test data. A machine learning (ML) model is used as a surrogate to predict the BFS and the number of eroded elements. Finally, optimized material model parameters are obtained through ML-based surrogate model and Bayesian optimization algorithm. The final validation of the developed framework is carried out using laboratory ballistic test data involving multiple shots on the shoot pack. The results indicate that reliable predictive data can be obtained using the developed process, and likely, can be extended for use in modeling other impact simulations. [ABSTRACT FROM AUTHOR]

PLA and its blends are the most extensively used materials for various biomedical applications such as scaffolds, implants, and other medical devices. The most extensively used method for tubular scaffold fabrication is by using the extrusion process. However, PLA scaffolds show limitations such as low mechanical strength as compared to metallic scaffolds and inferior bioactivities, limiting their clinical application. Thus, in order to improve the mechanical properties of tubular scaffolds, they were biaxially expanded, wherein the bioactivity can be improved by surface modifications using UV treatment. However, detailed studies are needed to study the effect of UV irradiation on the surface properties of biaxially expanded scaffolds. In this work, tubular scaffolds were fabricated using a novel single-step biaxial expansion process, and the surface properties of the tubular scaffolds after different durations of UV irradiation were evaluated. The results show that changes in the surface wettability of scaffolds were observed after 2 min of UV exposure, and wettability increased with the increased duration of UV exposure. FTIR and XPS results were in conjunction and showed the formation of oxygen-rich functional groups with the increased UV irradiation of the surface. AFM showed increased surface roughness with the increase in UV duration. However, it was observed that scaffold crystallinity first increased and then decreased with the UV exposure. This study provides a new and detailed insight into the surface modification of the PLA scaffolds using UV exposure. [ABSTRACT FROM AUTHOR]