In vivo biocompatibility and biodegradability of poly(lactic acid)/poly(ε-caprolactone) blend compatibilized with poly(ε-caprolactone-b-tetrahydrofuran) in Wistar rats

Spin-Coating Fabrication Method of PDMS/NdFeB Composites Using Chitosan/PCL Coating

This paper verified the possibility of applying chitosan and/or ferulic acid or polycaprolactone (PCL)-based coatings to polydimethylsiloxane/neodymium-iron-boron (PDMS/NdFeB) composites using the spin-coating method. The surface modification of magnetic composites by biofunctional layers allows for the preparation of materials for biomedical applications. Biofunctional layered magnetic composites were obtained in three steps. The spin-coating method with various parameters (time and spin speed) was used to apply different substances to the surface of the composites. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were used to analyze the thickness and surface topography. The contact angle of the obtained surfaces was tested. Increasing spin speed and increasing process time for the same speed resulted in decreasing the composite's thickness. The linear and surface roughness for the prepared coatings were approximately 0.2 μm and 0.01 μm, respectively, which are desirable values in the context of biocompatibility. The contact angle test results showed that both the addition of chitosan and PCL to PDMS have reduced the contact angle θ from 105° for non-coated composite to θ~59-88° depending on the coating. The performed modifications gave promising results mainly due to making the surface hydrophilic, which is a desirable feature of projected biomaterials.

Biodegradable Polymers in Veterinary Medicine-A Review

During the past two decades, tremendous progress has been made in the development of biodegradable polymeric materials for various industrial applications, including human and veterinary medicine. They are promising alternatives to commonly used non-degradable polymers to combat the global plastic waste crisis. Among biodegradable polymers used, or potentially applicable to, veterinary medicine are natural polysaccharides, such as chitin, chitosan, and cellulose as well as various polyesters, including poly(ε-caprolactone), polylactic acid, poly(lactic-co-glycolic acid), and polyhydroxyalkanoates produced by bacteria. They can be used as implants, drug carriers, or biomaterials in tissue engineering and wound management. Their use in veterinary practice depends on their biocompatibility, inertness to living tissue, mechanical resistance, and sorption characteristics. They must be designed specifically to fit their purpose, whether it be: (1) facilitating new tissue growth and allowing for controlled interactions with living cells or cell-growth factors, (2) having mechanical properties that address functionality when applied as implants, or (3) having controlled degradability to deliver drugs to their targeted location when applied as drug-delivery vehicles. This paper aims to present recent developments in the research on biodegradable polymers in veterinary medicine and highlight the challenges and future perspectives in this area.

Resistance to Degradation of Silk Fibroin Hydrogels Exposed to Neuroinflammatory Environments

Central nervous system (CNS) diseases represent an extreme burden with significant social and economic costs. A common link in most brain pathologies is the appearance of inflammatory components that can jeopardize the stability of the implanted biomaterials and the effectiveness of therapies. Different silk fibroin scaffolds have been used in applications related to CNS disorders. Although some studies have analyzed the degradability of silk fibroin in non-cerebral tissues (almost exclusively upon non-inflammatory conditions), the stability of silk hydrogel scaffolds in the inflammatory nervous system has not been studied in depth. In this study, the stability of silk fibroin hydrogels exposed to different neuroinflammatory contexts has been explored using an in vitro microglial cell culture and two in vivo pathological models of cerebral stroke and Alzheimer's disease. This biomaterial was relatively stable and did not show signs of extensive degradation across time after implantation and during two weeks of in vivo analysis. This finding contrasted with the rapid degradation observed under the same in vivo conditions for other natural materials such as collagen. Our results support the suitability of silk fibroin hydrogels for intracerebral applications and highlight the potentiality of this vehicle for the release of molecules and cells for acute and chronic treatments in cerebral pathologies.

Physico-mechanical and in-vivo evaluations of tri-layered alginate-gelatin/polycaprolactone-gelatin-β-TCP membranes for guided bone regeneration

Guided bone regeneration (GBR) membranes favor periodontal regrowth, but they still have certain limitations, such as improper biodegradation and poor mechanical property. To overcome these shortcomings, we have generated a unique multifunctional membrane. A polycaprolactone/gelatin/β-TCP and alginate/gelatin trilayered construction was fabricated through electrospinning and casting technology. The prepared membranes have suitable physicomechanical and in-vitro properties to confirm the compatibility of the product in the body. Phase analysis, functional groups, surface microstructure, and contact angle were measured as basic characteristics. For a mechanical performance evaluation, the tensile strength at suturing point was measured through pullout tensile strength test, and it showed the suture capability of bi-layered membranes. Highest tensile strength for A75G25 was recorded with 2.9 ± 0.15 MPa with 105% strain. Further, the osteoblast and fibroblast-type cell toxicity results showed that the electrospun membrane offered compatible environment to cells while the alginate sheet was found to be sufficiently capable to suppress the cellular attachment while also being a nontoxic material. Post-implantation, according to the in-vivo conclusions of the tri-layered membrane, there was appreciable bone formation. Compared to an implant without membrane covering, enhanced new bone formation can be identified after 8 weeks of implantation with P1G4β10 membranes-covered site.

Advanced strategies to thwart foreign body response to implantable devices

Mitigating the foreign body response (FBR) to implantable medical devices (IMDs) is critical for successful long-term clinical deployment. The FBR is an inevitable immunological reaction to IMDs, resulting in inflammation and subsequent fibrotic encapsulation. Excessive fibrosis may impair IMDs function, eventually necessitating retrieval or replacement for continued therapy. Therefore, understanding the implant design parameters and their degree of influence on FBR is pivotal to effective and long lasting IMDs. This review gives an overview of FBR as well as anti-FBR strategies. Furthermore, we highlight recent advances in biomimetic approaches to resist FBR, focusing on their characteristics and potential biomedical applications.

Tailored alginate/PCL-gelatin-β-TCP membrane for guided bone regeneration

Membranes prepared for guided bone regeneration (GBR) signify valued resources, inhibiting fibrosis and assisting bone regenration. However, existing membranes lack bone regenerative capacity or adequate degradation profile. An alginate-casted polycaprolactone (PCL)-gelatin-β-tricalcium phosphate (β-TCP) dual membrane was fabricated by electrospinning and casting processes to enhance new bone formation under a guided bone regeneration (GBR) process. Porous membranes were synthesized with suitable hydrophilicity, swelling, and degradation behavior to confirm the compatibility of the product in the body. Furthermore, osteoblast-type cell toxicity and cell adhesion results showed that the electrospun membrane offered compatible environment to cells while the alginate sheet was found capable enough to supress the cellular attachment, but was a non-toxic material. Post-implantation, the in-vivo outcomes of the dual-layered membrane, showed appreciable bone formation. Significantly, osteoid islands had fused in the membrane group by 8 weeks. The infiltration of fibrous tissues was blocked by the alginate membrane, and the ingrowth of new bone was enhanced. Immunocytochemical analysis indicated that the dual membrane could direct more proteins which control mineralization and convene osteoconductive properties of tissue-engineered bone grafts.

Long-Term Evaluation of Poly(lactic acid) (PLA) Implants in a Horse: An Experimental Pilot Study

In horses, there is an increasing interest in developing long-lasting drug formulations, with biopolymers as viable carrier alternatives in addition to their use as scaffolds, suture threads, screws, pins, and plates for orthopedic surgeries. This communication focuses on the prolonged biocompatibility and biodegradation of PLA, prepared by hot pressing at 180 °C. Six samples were implanted subcutaneously on the lateral surface of the neck of one horse. The polymers remained implanted for 24 to 57 weeks. Physical examination, plasma fibrinogen, and the mechanical nociceptive threshold (MNT) were performed. After 24, 28, 34, 38, and 57 weeks, the materials were removed for histochemical analysis using hematoxylin-eosin and scanning electron microscopy (SEM). There were no essential clinical changes. MNT decreased after the implantation procedure, returning to normal after 48 h. A foreign body response was observed by histopathologic evaluation up to 38 weeks. At 57 weeks, no polymer or fibrotic capsules were identified. SEM showed surface roughness suggesting a biodegradation process, with an increase in the median pore diameter. As in the histopathological evaluation, it was not possible to detect the polymer 57 weeks after implantation. PLA showed biocompatible degradation and these findings may contribute to future research in the biomedical area.