Composite Implants Research Articles

Functional and structural construction of photothermal-responsive PEEK composite implants to promote bone regeneration and bone-implant integration

Although poly (ether-ether-ketone) (PEEK) has been widely used in orthopedic surgeries, its clinical efficacy is challenged by ineffective bone regeneration and insufficient osteointegration. Herein, inspired by the Mortise-and-tenon joint in traditional Chinese architectural art, a novel strategy has been developed to construct photothermal-responsive PEEK composite implants, with tapered lock-groove edges as proof of concept, by incorporating graphene oxide (GO) loaded with polydopamine-coated nano-zirconia (PDA@ZrO2) into PEEK (namely PGPZ composite). The PGPZ composite exhibits improved mechanical properties, good cytocompatibility and blood compatibility, excellent antibacterial ability and osteogenic activity remotely controlled by near-infrared irradiation (NIR). The cranial defects experiment on rabbits reveals that repeated NIR treatment on PGPZ composite implant significantly accelerates endogenous bone regeneration. More importantly, abundant newly-formed bone has materialized in the lock grooves, forming interlocked Mortise-and-tenon joints with the implant. This study not only pave the way for further clinical applications of the PEEK composite implants with improved bioactivities to promote bone regeneration and osteointegration, but also providing a novel strategy for structural and functional design of various tissue engineering implants.

Peculiarities of regeneration of an experimental femur fracture in rats with intramedullary fixation with carbon-carbon composite material implants

the issue of finding modern bioinert materials for use in surgical orthopedics and traumatology, as well as other medical fields related to the surgical treatment of diseases of the musculoskeletal system, is the most urgent today. The aim of the study was to establish the features of the course of regeneration of a femur fracture in rats with intramedullary fixation of fragments with a carbon-carbon composite material. The femur of 12 Wistar rats was studied in the work. Six rats - with simulated transverse diaphyseal fracture and intramedullary fixation with carbon-carbon composite material and six rats - with simulated transverse diaphyseal fracture and intramedullary fixation with medical steel. The last one were used as a comparison group. Histological sections prepared according to standard methods for inspection microscopy were stained with hematoxylin and eosin. To study revascularization processes, an immunohistochemical reaction with CD-34 antibodies was performed. As a result of the study, it was established that in animals with a simulated complete transverse diaphyseal fracture of the femur and intramedullary fixation with implants made of carbon-carbon composite material in the bone regenerate, the relative area of ​​CD-34+ vascular endothelial cells probably increases compared to the group of animals in which fixation was performed using medical stainless steel. Thus, the use of carbon-carbon composite material reveals an angiogenic effect in bone regeneration, which accelerates the rate of repair and remodeling of fractures.

Agarose-collagen composite microsphere implants: A biocompatible and robust approach for skin tissue regeneration

Photoaged skin, a consequence of UV radiation-induced collagen degradation, presents a significant challenge for skin rejuvenation. Synthetic polymer microspheres, while offering collagen regeneration potential, carry risks like granulomas. To overcome this, we developed a novel agarose-collagen composite microsphere implant for skin tissue regeneration. Fabricated using an emulsification-crosslinking method, these microspheres exhibited excellent uniformity and sphericity (with a diameter of ~38.5 μm), as well as attractive injectability. In vitro studies demonstrated their superior biocompatibility, promoting cell proliferation, adhesion, and migration. Further assessments revealed favorable biosafety and blood compatibility. In vivo experiments in photoaged mice showed that implantation of these microspheres effectively reduced wrinkles, increased skin density, and improved elasticity by stimulating fibroblast encapsulation and collagen regeneration. These findings highlight the potential of agarose-collagen microspheres in dermatological and tissue engineering applications, offering a safer alternative for skin rejuvenation.

In vitro and in vivo dissolution of biocompatible S59 glass scaffolds

Fabrication of porous tissue-engineering scaffolds from bioactive glasses (BAG) is complicated by the tendency of BAG compositions to crystallize in thermal treatments during scaffold manufacture. Here, experimental biocompatible glass S59 (SiO2 59.7 wt%, Na2O 25.5 wt%, CaO 11.0 wt%, P2O5 2.5 wt%, B2O3 1.3 wt%), known to be resistant to crystallization, was used in sintering of glass granules (300–500 µm) into porous scaffolds. The dissolution behavior of the scaffolds was then studied in vivo in rabbit femurs and under continuous flow conditions in vitro (14 days in vitro/56 days in vivo). The scaffolds were osteoconductive in vivo, as bone could grow into the scaffold structure. Still, the scaffolds could not induce sufficiently rapid bone ingrowth to replace the strength lost due to dissolution. The scaffolds lost their structure and strength as the scaffold necks dissolved. In vitro, S59 dissolved congruently throughout the 14-day experiments, resulting in only a slight reaction layer formation. Manufacturing BAG scaffolds from S59 that retain their amorphous structure was thus possible. The relatively rapid and stable dissolution of the scaffold implies that the glass S59 may have the potential to be used in composite implants providing initial strength and stable, predictable release of ions over longer exposure times.Graphical

Study of compaction-free fabrication of topologically ordered functionally graded iron-hydroxyapatite-zinc biodegradable composite implants

Study of compaction-free fabrication of topologically ordered functionally graded iron-hydroxyapatite-zinc biodegradable composite implants

Improved Recovery of Complete Spinal Cord Transection by a Plasma-Modified Fibrillar Scaffold.

Complete spinal cord injury causes an irreversible disruption in the central nervous system, leading to motor, sensory, and autonomic function loss, and a secondary injury that constitutes a physical barrier preventing tissue repair. Tissue engineering scaffolds are presented as a permissive platform for cell migration and the reconnection of spared tissue. Iodine-doped plasma pyrrole polymer (pPPy-I), a neuroprotective material, was applied to polylactic acid (PLA) fibers and implanted in a rat complete spinal cord transection injury model to evaluate whether the resulting composite implants provided structural and functional recovery, using magnetic resonance (MR) imaging, diffusion tensor imaging and tractography, magnetic resonance spectroscopy, locomotion analysis, histology, and immunofluorescence. In vivo, MR studies evidenced a tissue response to the implant, demonstrating that the fibrillar composite scaffold moderated the structural effects of secondary damage by providing mechanical stability to the lesion core, tissue reconstruction, and significant motor recovery. Histologic analyses demonstrated that the composite scaffold provided a permissive environment for cell attachment and neural tissue guidance over the fibers, reducing cyst formation. These results supply evidence that pPPy-I enhanced the properties of PLA fibrillar scaffolds as a promising treatment for spinal cord injury recovery.

In vitro and in vivo evaluation of the osseointegration capacity of a polycarbonate-urethane zirconium-oxide composite material for application in a focal knee resurfacing implant.

Currently available focal knee resurfacing implants (FKRIs) are fully or partially composed of metals, which show a large disparity in elastic modulus relative to bone and cartilage tissue. Although titanium is known for its excellent osseointegration, the application in FKRIs can lead to potential stress-shielding and metal implants can cause degeneration of the opposing articulating cartilage due to the high resulting contact stresses. Furthermore, metal implants do not allow for follow-up using magnetic resonance imaging (MRI).To overcome the drawbacks of using metal based FKRIs, a biomimetic and MRI compatible bi-layered non-resorbable thermoplastic polycarbonate-urethane (PCU)-based FKRI was developed. The objective of this preclinical study was to evaluate the mechanical properties, biocompatibility and osteoconduction of a novel Bionate® 75D - zirconium oxide (B75D-ZrO2) composite material in vitro and the osseointegration of a B75D-ZrO2 composite stem PCU implant in a caprine animal model. The tensile strength and elastic modulus of the B75D-ZrO2 composite were characterized through in vitro mechanical tests under ambient and physiological conditions. In vitro biocompatibility and osteoconductivity were evaluated by exposing human mesenchymal stem cells to the B75D-ZrO2 composite and culturing the cells under osteogenic conditions. Cell activity and mineralization were assessed and compared to Bionate® 75D (B75D) and titanium disks. The in vivo osseointegration of implants containing a B75D-ZrO2 stem was compared to implants with a B75D stem and titanium stem in a caprine large animal model. After a follow-up of 6 months, bone histomorphometry was performed to assess the bone-to-implant contact area (BIC). Mechanical testing showed that the B75D-ZrO2 composite material possesses an elastic modulus in the range of the elastic modulus reported for trabecular bone. The B75D-ZrO2 composite material facilitated cell mediated mineralization to a comparable extent as titanium. A significantly higher bone-to-implant contact (BIC) score was observed in the B75D-ZrO2 implants compared to the B75D implants. The BIC of B75D-ZrO2 implants was not significantly different compared to titanium implants. A biocompatible B75D-ZrO2 composite approximating the elastic modulus of trabecular bone was developed by compounding B75D with zirconium oxide. In vivo evaluation showed an significant increase of osseointegration for B75D-ZrO2 composite stem implants compared to B75D polymer stem PCU implants. The osseointegration of B75D-ZrO2 composite stem PCU implants was not significantly different in comparison to analogous titanium stem metal implants.

Effects of selective laser melting process parameters on 3D-printing of Ti6Al4V/ST316L composite material and their optimization using response surface methodology

The mechanical properties of Ti6Al4V and ST316L bone implants make them superior to natural bone, which results in fewer contact points with the bone. Different manufacturing processes, such as selective laser melting (SLM), may result in different mechanical properties between Ti-6Al-4V and ST316L implants. Sustainable development for the composite implants was optimized (SLM) in this study to minimize their compressive strength and Young's modulus. A three-dimensional printing process using SLM was optimized based on laser power, hatch distance, laser velocity, and ST316L weight percentage. Composite implants made from titanium alloys and steel alloys were evaluated using response surface methodology (RSM). ST316L composition has been found to influence the mechanical properties of composites in a significant manner, based on the results of parameter optimization. Using Ti6Al4V/ST316L as a biomaterial in knee joint prostheses is possible.

Development of patient-specific finite element model for study of composite dental implants

Traumatic dental injuries can occur due to various reasons such as accidents, sports injuries, fights, falls, and others. These injuries can affect the teeth, gums, and surrounding tissues, and can range from minor chips and cracks to severe fractures, dislocations, and avulsions (when the tooth is completely knocked out of the socket). The most common way to address this is by replacing affected teeth with dental implants. The purpose of this research is to evaluate the use of composite materials in dental implants and compare them with the traditionally used materials using a patient specific cone beam computed tomography (CBCT) based finite element model (FEM). To conduct this research, two different implant groups i.e., traditional implant and composite implant were designed using Titanium grade 4, zirconium oxide-reinforced lithium silicate (ZLS), and Zirconia (ZrO2). Six dental implants were designed namely Ti implant, ZLS implant, ZrO2 implant, Ti-ZrO2 composite, Ti-ZLS composite, and ZLS-ZrO2 composite using 3D modelling software. Detailed full-scale 3D models of patient specific dental implant were developed and traumatic loading conditions were applied to the enamel of central incisor teeth or crown of dental implant, and maxilla was constrained in all directions. It was found that the use of composite materials for dental implants can reduce the stresses over the surface of abutment and implant as compared to traditional implants. The detailed models developed as a part of this study can advance the research on dental implants, and with further experimental validation allow the use of composite materials for fabrication of more stable dental implants.

Design, clinical applications and post-surgical assessment of bioresorbable 3D-printed craniofacial composite implants.

This study details the design, fabrication, clinical trials' evaluation, and analysis after the clinical application of 3D-printed bone reconstruction implants made of nHAp@PLDLLA [nanohydroxyapatite@poly(L-lactide-co-D,L-lactide)] biomaterial. The 3D-printed formulations have been tested as bone reconstruction Cranioimplants in 3 different medical cases, including frontal lobe, mandibular bone, and cleft palate reconstructions. Replacing one of the implants after 6 months provided a unique opportunity to evaluate the post-surgical implant obtained from a human patient. This allowed us to quantify physicochemical changes and develop a spatial map of osseointegration and material degradation kinetics as a function of specific locations. To the best of our knowledge, hydrolytic degradation and variability in the physicochemical and mechanical properties of the biomimetic, 3D-printed implants have not been quantified in the literature after permanent placement in the human body. Such analysis has revealed the constantly changing properties of the implant, which should be considered to optimize the design of patient-specific bone substitutes. Moreover, it has been proven that the obtained composition can produce biomimetic, bioresorbable and bone-forming alloplastic substitutes tailored to each patient, allowing for shorter surgery times and faster patient recovery than currently available methods.

The influence of polylactide/hydroxyapatite composite material crystallinity on the polymer structure degradation rate

Introduction Assessment of biological characteristics of polylactide/hydroxyapatite (PLLA/HA) biodegradable materials is requiered to specify indications for the use of PLLA/HA composite implants in clinical practice.The present study was aimed to measure the kinetics of calcium and phosphate release from PLLA and its dependence on polymer structure crystallinity. Material and methods Four types of biodegradable materials were studied in vitro. Samples of type 1 and type 3 made of crystalline PLLA after annealing contained 25 % and 50 % of HA mass fraction, respectively. Samples of type 2 and type 4 made of amorphous PLLA (without annealing) contained 25 % and 50 % of HA mass fraction, respectively. In every group, 6 samples were tested. The samples were incubated in an aqueous medium at 37 °C for 52 weeks. The rate of PLLA degradation was assessed by the accumulation of lactate monomer in the hydrolysate. The concentrations of calcium ions and phosphate ions were determined for assessment the HA hydrolysis rate. The degree of crystallinity of the polymer matrix was evaluated by scanning calorimetry.Results The hydrolysis of PLLA and HA in the samples was not simultaneous. The PLLA was hydrolyzed first followed by HA hydrolysis. By the moment of complete hydrolysis of PLLA, there was only 15 % of hydrolyzed HA. The release of calcium ions occurred from the sixth week of incubation for all tested samples, that of phosphate ions from the third week. The total amount of the released calcium ions and phosphate ions decreased in the line: material 3 > material 4 > material 1 > material 2. Calcium ions in the hydrolysates were detected up to 42 weeks of incubation, phosphate ions up to the 52nd week.Conclusion Higher crystallinity of PLLA achieved by annealing results in increased rate of hydrolysis of HA from PLLA matrix. Biological activity of PLLA/HA implants can be determined by degree of polymer crystallinity and saturation with HA.

Osseointegration enhancement by controlling dispersion state of carbonate apatite in polylactic acid implant

Osteoconductive ceramics (OCs) are often used to endow polylactic acid (PLA) with osseointegration ability. Conventionally, OC powder is dispersed in PLA. However, considering cell attachment to the implant, OCs may be more favorable when they exist in the form of aggregations, such as granules, and are larger than the cells rather than being dispersed like a powder. In this study, to clarify the effects of the dispersion state of OCs on the osseointegration ability, carbonate apatite (CAp), a bone mineral analog that is osteoconductive and bioresorbable, powder–PLA (P-PLA), and CAp granule–PLA (G-PLA) composite implants were fabricated via thermal pressing. The powder and granule sizes of CAp were approximately 1 and 300–600 µm, respectively. G-PLA exhibited a higher water wettability and released calcium and phosphate ions faster than P-PLA. When cylindrical G-PLA, P-PLA, and PLA were implanted in rabbit tibial bone defects, G-PLA promoted bone maturation compared to P-PLA and pure PLA. Furthermore, G-PLA bonded directly to the host bone, whereas P-PLA bonded across the osteoid layers. Consequently, the bone-to-implant contact of G-PLA was 1.8- and 5.6-fold higher than those of P-PLA and PLA, respectively. Furthermore, the adhesive shear strength of G-PLA was 1.9- and 3.0-fold higher than those of P-PLA and PLA, respectively. Thus, G-PLA achieved earlier and stronger osseointegration than P-PLA or PLA. The findings of this study highlight the significance of the state of dispersion of OCs in implants as a novel strategy for material development.

A PEEK into carbon fiber: A practical guide for high performance composite polymeric implants for orthopaedic oncology

IntroductionThe use of carbon fiber implants in orthopaedic oncology has increased within recent years. The most widely used type of polymer is carbon fiber polyether ether ketone (CF-PEEK). Its radiolucency enables targeted radiotherapy and artifact-free tumor surveillance, which provides major advantages over metallic hardware. We aim to summarize the unique benefits within orthopaedic oncology, clinical pitfalls, and recent advancements. MethodsFour representative patient cases from a single tertiary academic medical center were treated with carbon fiber implants (n = 2 nails, n = 2 plates) from 2021 to 2022. ResultsThere were no adverse events noted during intraoperative implantation or postoperative follow up. All patients reported improvements in pain and no difficulties in ambulation. There were no instances of catastrophic failure or implant loosening. ConclusionCF implants offer a diverse array of advantages regarding its radiolucency, low scatter density, and bioinert profile. Nonetheless, further research is required to understand the long-term surgical outcomes and robustness of CF implants. Multi institutional trials could address important aspects of durability and stability over extended periods, feasibility and ease-of-use for different anatomical sites and bone quality, as well as cost-effectiveness in post-operative imaging, healthcare resource utilization, and revision rates. Providing orthopaedic surgeons with valuable insight will enable thorough clinically supported, informed decision making regarding optimal use of implants.

Resorbable Layered Double Hydroxides‐Based Composite Implants Synergistically Accelerates Critical‐Sized Defect Closure

AbstractThe study focuses on the fabrication of a composite implant composed of MgAl layered double hydroxides (LDH), gelatin, and diosgenin and its regeneration potential in experimentally‐induced tibial defect in rabbits. The implant is fabricated by blending and lyophilization technique and eventually cross‐linked using glutaraldehyde. The implant is characterized by attenuated total reflectance (ATR) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and compressive strength. A sustained release of diosgenin occurs over a period of 28 days. The osteogenic activity is analyzed by alkaline phosphatase activity and alizarin red S staining; that aid in determining the extent of biomineralization. The results also demonstrate that LGD100 implant stimulates the expression of genes associated with osteoblastic activities in MG‐63 cells, namely type I collagen, osteocalcin, and osteopontin. The bone regeneration capacity of diosgenin‐loaded gelatin‐based LDH implant is then tested by creating critical bone defects in the tibia of rabbits by using empty bone defects as controls. Periodic radiographs are taken which show promising results. Histological and immunohistochemical staining confirm that after treatment with LGD100, new bone is formed at the defect site. This study suggests that LGD100 implant aids in faster bone formation as it mimics the natural properties of bone.

Accuracy of Orbital Shape Reconstruction-Comparative Analysis of Errors in Implant Shape Versus Implant Positioning: A Cadaveric Study.

Orbital blowout fractures are commonly reconstructed with implants shaped to repair orbital cavity defects, restore ocular position and projection, and correct diplopia. Orbital implant shaping has traditionally been performed manually by surgeons, with more recent use of computer-assisted design (CAD). Accuracy of implant placement is also key to reconstruction. This study compares the placement accuracy of orbital implants, testing the hypothesis that CAD-shaped implants indexed to patient anatomy will better restore orbit geometry compared with manually shaped implants and manually placed implants. The placement accuracy of orbital implants was assessed within a cadaveric blowout fracture model (3 skulls, 6 orbits) via 3-dimensional CT analysis. Defects were repaired with 4 different techniques: manually placed-manually shaped composite (titanium-reinforced porous polyethylene), manually placed CAD composite, indexed placed CAD composite, and indexed placed CAD titanium mesh. Implant placement accuracy differed significantly with the implant preparation method ( P =0.01). Indexing significantly improved the placement accuracy ( P =0.002). Indexed placed titanium mesh CAD implants (1.42±0.33mm) were positioned significantly closer to the intact surface versus manually placed-manually shaped composite implants (2.12±0.39mm). Computer-assisted design implants indexed to patient geometry yielded average errors below the acceptable threshold (2mm) for enophthalmos and diplopia. This study highlights the importance of adequately indexing CAD-designed implants to patient geometry to ensure accurate orbital reconstructions.

Hierarchically Porous Implants Orchestrating a Physiological Viscoelastic and Piezoelectric Microenvironment for Bone Regeneration.

The extracellular matrix microenvironment of bone tissue comprises several physiological cues. Thus, artificial bone substitute materials with a single cue are insufficient to meet the demands for bone defect repair. Regeneration of critical-size bone defects remains challenging in orthopedic surgery. Intrinsic viscoelastic and piezoelectric cues from collagen fibers play crucial roles in accelerating bone regeneration, but scaffolds or implants providing integrated cues have seldom been reported. In this study, we aimed to design and prepare hierarchically porous poly(methylmethacrylate)/polyethyleneimine/poly(vinylidenefluoride) composite implants presenting a similar viscoelastic and piezoelectric microenvironment to bone tissue via anti-solvent vapor-induced phase separation. The viscoelastic and piezoelectric cues of the composite implants for human bone marrow mesenchymal stem cell line stimulated and activated Piezo1 proteins associated with mechanotransduction signaling pathways. Cortical and spongy bone exhibited excellent regeneration and integration in models of critical-size bone defects on the knee joint and femur in vivo. This study demonstrated that implants with integrated physiological cues were promising artificial bone substitute materials for regenerating critical-size bone defects. This article is protected by copyright. All rights reserved.

A novel 3D woven carbon fiber composite with super interlayer performance hybridized by CNT tape and copper wire simultaneously

Abstract In this work, a novel binary hybrid woven carbon nanotube (CNT) tape/copper wire carbon fiber reinforced epoxy resin composite is prepared. The mode I interlaminar fracture toughness (G IC) is employed to critically evaluate the delamination performance. A comparison of the G IC value with that of the carbon fiber reinforced composite confirms that incorporating CNT tapes and copper wires into the composite increases the value by 263%. In the transverse and through-thickness direction, the conductivity of the laminate increases to 458 and 193 S/m, which is increased by 196 and 675%, respectively. The thermal conductivity along the thickness direction is increased to 2.27 W/m K, an increase of 134%. The volume fraction of CNT tapes and copper wire are as low as approximately 0.87 and 0.47 vol%, respectively. 3D woven composites have potential applications in high-performance structures and lightning striking protection such as aircraft, ships, and engines, which benefits by the innovative through-thickness implantation of composites using CNT tape and copper wire.

Evaluation of surgical fixation methods for the implantation of melt electrowriting-reinforced hyaluronic acid hydrogel composites in porcine cartilage defects.

The surgical repair of articular cartilage remains an ongoing challenge in orthopedics. Tissue engineering is a promising approach to treat cartilage defects; however, scaffolds must (i) possess the requisite material properties to support neocartilage formation, (ii) exhibit sufficient mechanical integrity for handling during implantation, and (iii) be reliably fixed within cartilage defects during surgery. In this study, we demonstrate the reinforcement of soft norbornene-modified hyaluronic acid (NorHA) hydrogels via the melt electrowriting (MEW) of polycaprolactone to fabricate composite scaffolds that support encapsulated porcine mesenchymal stromal cell (pMSC, three donors) chondrogenesis and cartilage formation and exhibit mechanical properties suitable for handling during implantation. Thereafter, acellular MEW-NorHA composites or MEW-NorHA composites with encapsulated pMSCs and precultured for 28 days were implanted in full-thickness cartilage defects in porcine knees using either bioresorbable pins or fibrin glue to assess surgical fixation methods. Fixation of composites with either biodegradable pins or fibrin glue ensured implant retention in most cases (80%); however, defects treated with pinned composites exhibited more subchondral bone remodeling and inferior cartilage repair, as evidenced by micro-computed tomography (micro-CT) and safranin O/fast green staining, respectively, when compared to defects treated with glued composites. Interestingly, no differences in repair tissue were observed between acellular and cellularized implants. Additional work is required to assess the full potential of these scaffolds for cartilage repair. However, these results suggest that future approaches for cartilage repair with MEW-reinforced hydrogels should be carefully evaluated with regard to their fixation approach for construct retention and surrounding cartilage tissue damage.

Phosphorylcholine and KR12-Containing Corneal Implants in HSV-1-Infected Rabbit Corneas.

Severe HSV-1 infection can cause blindness due to tissue damage from severe inflammation. Due to the high risk of graft failure in HSV-1-infected individuals, cornea transplantation to restore vision is often contraindicated. We tested the capacity for cell-free biosynthetic implants made from recombinant human collagen type III and 2-methacryloyloxyethyl phosphorylcholine (RHCIII-MPC) to suppress inflammation and promote tissue regeneration in the damaged corneas. To block viral reactivation, we incorporated silica dioxide nanoparticles releasing KR12, the small bioactive core fragment of LL37, an innate cationic host defense peptide produced by corneal cells. KR12 is more reactive and smaller than LL37, so more KR12 molecules can be incorporated into nanoparticles for delivery. Unlike LL37, which was cytotoxic, KR12 was cell-friendly and showed little cytotoxicity at doses that blocked HSV-1 activity in vitro, instead enabling rapid wound closure in cultures of human epithelial cells. Composite implants released KR12 for up to 3 weeks in vitro. The implant was also tested in vivo on HSV-1-infected rabbit corneas where it was grafted by anterior lamellar keratoplasty. Adding KR12 to RHCIII-MPC did not reduce HSV-1 viral loads or the inflammation resulting in neovascularization. Nevertheless, the composite implants reduced viral spread sufficiently to allow stable corneal epithelium, stroma, and nerve regeneration over a 6-month observation period.

Composite bone-implant engineered with magnesium and variable degradation for orthopaedics

Metallic biomaterials are suitable for load-bearing scaffolds, and magnesium (Mg) alloy is the most preferable because of its mechanical properties are comparable to those of hard tissue (bone). The most important characteristic of an implant is its biocompatibility and Mg fully satisfies this standard. Mg is also biodegradable, thereby avoiding the need for secondary surgery. An uncontrollable degradation rate is one of the most significant limitations of magnesium-based implants, which hinders their applications in bone tissue engineering. Hydroxyapatite (HAP), a bioactive material, was incorporated into a magnesium metal matrix as a catalyst for enhancing bone tissue regeneration. Porosity in the scaffold could serve as a conduit for nutrients and also aids in the scaffold's weight reduction. This study investigated the effect of selective alloying elements (Ca, Zn, and Fe) on the biodegradability of scaffolds. Powder metallurgy was used to produce the magnesium alloy scaffolds. A calculated quantity of porogen particles, carbamide (urea), was incorporated into the Mg-Ca-Zn-Fe matrix in order to achieve 30% and 50% porosity. Due to the formation of Mg-Ca-Zn-Fe intermetallic compounds, the current study establishes that Mg alloy-based samples exhibit favorable biodegradation behavior. After seven days of immersion, the pH of the immersion liquid had also been found to have stabilized. Consequently, the observations suggest that the biodegradation behavior of bone implants could be modified by developing composite porous magnesium alloy implants.