Controllable Degradation Rate Research Articles

Magnesium-Based Biomedical Devices Degradation Control by Means of Multilayer Coatings

Sometimes, in surgical procedure following an accident or illness it is necessary to use metal prostheses or implants to ensure the functionality of bones and joint systems. From time to time, at the end of the patient's healing process, it is necessary to remove the medical device used. In these cases, it would be useful to use resorbable devices to avoid further surgery. A possible solution to the problem could be to use metal alloy devices that degrade over time, while ensuring the functionality of the system. Unfortunately, the chemical compounds generated by the corrosion processes of metal alloys used in the medical field are almost always harmful to human health. The products generated by the degradation processes of some magnesium alloys, on the other hand, are not considered toxic or harmful to human health, so that a device showing controllable degradation rate can be used, guaranteeing the functionality of the implanted device. To achieve this goal, a possible solution could include the use of one or more coatings, capable of controlling the metal degradation process. To do this, we used a first coating obtained by subjecting the samples to a direct current (DC) plasma electrolytic oxidation (PEO) treatment, carried out in an alkaline solution based on silicates and sodium. Subsequently, the samples were coated with a polydopamine (PDOPA) film by dip-coating, and, at the end, a l-polylactic acid (PLLA) coating was applied on the sample by hot-pressing. The coupons were subjected to morphological characterization by Scanning Electron Spectroscopy (SEM) and to electrochemical characterization in Hank's solution at 37°C by means of electrochemical impedance spectroscopy (EIS). The experimental results obtained demonstrate that the coupling of the PEO oxide with the polydopamine and the polymeric film show properties such as to allow the creation of devices which permit the control of the metal degradation process.

Friction stir processing of AZ31 alloy to improve the mechanical, biodegradation, and in vitro biocompatible characteristics

The aim of the study was to improve the mechanical, biodegradation and in vitro biocompatible characteristics of as received rolled AZ31 (Mg-1%Zn-3%Al) alloy by develop the surface composite of Mg-Titania. The surface composite was developed by friction stir processing (FSP) and it’s used for prosthetic applications. The influence of tool rotation speed and number of FSP passes on grain structure, grain refinement, tensile strength, hardness, in vitro degradation rate and in vitro biocompatibility were explored. The obtained results support the capability of FSP in terms of mechanical strengthening, refinement of grain structure, dispersion of reinforcement (i.e. TiO2) and controlled degradation rate. Grain structure at stir zone, advancing side and retreating side were investigated. The large grains in the alloy were reduced to a fine equiaxial grains of average dimension of ≈ 3 μm by 3rd pass of FSP. The process was performed under two different tool rotation speed, i.e. 1550 and 2260 RPM. The addition of second phase in the matrix significantly improve the grain refinement. The results obtained from tensile test revealed the improvement in the percentage elongation without compromising the strength. The micro hardness of specimens of different parametric combination were evaluated and found ≈ 30–50% improvement in the micro hardness. The degradation rate by immersion test in simulated body fluid (SBF) for 3, 6 and 10 days were performed and found a significant reduction in degradation rate. The MTT assay for the biocompatibility performed by indirect method, the results validate the non-toxic behavior of processed specimen.

Calcium silicate biocomposites: effects of selenium oxide on the physico-mechanical features and their in-vitro biological assessments

Bone tissue regenerative material serves as a prospective recovery candidate with self-adaptable biological properties of bio-activation, degradability, compatibility, and antimicrobial efficacy instead of metallic implants. Such materials are highly expensive due to chemical reagents and complex synthesis procedures, making them unaffordable for patients with financial constraints. This research produced an efficient bone tissue regenerative material using inexpensive naturally occurring source materials, including silica sand and limestone. The extracted SiO2 and CaO particles (75:25 wt%) were subjected to hydrothermal synthesis (water treatment instead of chemical solvents) to produce the CaSiO3 biomaterial (code: S). Selenium oxide was doped with calcium silicate at 3, 5, and 10 wt.% to enhance its properties, yielding biocomposite materials (i.e. S3, S5, and S10). The physico-mechanical properties of these materials were investigated with x-ray diffraction, Fourier transform infrared, FESEM-EDS, and micro-universal testing machine. The results revealed that the synthesized biocomposites have a crystalline wollastonite phase with a porously fused rough surface. From structural parametric calculations, we found that the biocomposites have reduced particle size and enhanced surface area due to the influence of selenium oxide. The biocomposite S10, having high SeO2 content, attained the maximum compressive strength of 75.2 MPa. In-vitro studies of bioactivity, biodegradability, biocompatibility, and antibacterial activity were performed. At 7 and 14 d of bioactivity, the synthesized biocomposites are capable of dissolving their ions into simulated body fluid (SBF) solution to precipitate hydroxyapatite and a required Ca/P ratio of 1.69 was achieved by S3. A comparative analysis has been performed on the degradation activity in Tris-HCl and the consequent pH changes during SBF treatment. The bio-analysis revealed that the biocomposite S3 shows enhanced bioactivity through a controlled degradation rate and secured cell viability of 88% at a concentration of 100 μg ml−1. It also offers significant bacterial inhibition potency against E.coli and S.aureus bacteria.

Metastable FeMg particles for controlling degradation rate, mechanical properties, and biocompatibility of Poly(l-lactic) acid (PLLA) for orthopedic applications

Poly(l-lactic) acid (PLLA) is commonly used in bioabsorbable medical implants, but it suffers from slow degradation rate and rapid decline in mechanical properties for orthopedic applications. To address this drawback, recent research has explored the use of Mg as a filler for PLLA, resulting in composites with improved degradation rate and cytocompatibility compared to neat PLLA. In this study, FeMg powder particles were proposed as fillers for PLLA to investigate the potential of PLLA/FeMg composites for bioabsorbable implants. Cylinder specimens of PLLA, PLLA/Fe, PLLA/Mg and PLLA/FeMg were prepared using solvent casting followed by thermo-molding. The microstructure, thermal behavior, in vitro degradation behavior in simulated body fluid, mechanical properties and cytocompatibility of these composites were examined. The results indicate that the presence of FeMg particles prevents the deterioration of the composite mechanical properties, at least up to 14 days. Once a certain amount of degradation of the composite is reached, the degradation is faster than that of PLLA. Direct cytotoxicity assays revealed that pre-osteoblast MC3T3-E1 cells successfully adhered to and proliferated on the PLLA/FeMg surface. The inclusion of a low percentage of Mg into the Fe lattice not only accelerated the degradation rate of Fe but also improved its cytocompatibility. The enhanced degradation rate, mechanical properties, and osteoconductive properties of this composite make it a promising option for temporary orthopedic biomedical devices.

Comparing three strategies for surface treatment of Mg coated by hexamethylene diamine tetra methylene phosphonic acid for corrosion protection

Manufacturing Mg and Mg‐based alloys with controllable degradation rate has always been a challenge. Surface modification is one of the best ways to acquire protection against corrosion. Previously, many approaches such as phosphating (Na3PO4), fluoridation (HF), and alkalization (NaOH) treatments have been used to regulate the corrosion rate. Here, we compare the corrosion rates of 3‐surface modified Mg samples coated with hexamethylene diamine tetra methylene phosphonic (HMDTMPA). The protection of those different layers was ranked in the order: phosphate > alkaline > fluoridation treatment. The chemistry of those chemical conversion layers was discussed in the light of scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and X‐ray photoelectron spectroscopy (XPS). The mechanism of tailoring a protective film of HMDTMPA on phosphated Mg was discussed according to the ability of P to bridge the substrate with the coating.

Additive manufacturing a novel bioceramic bone scaffold with MgO/Ca3(PO4)2: Microstructure, mechanical property and controllable degradation behavior

Biodegradable bone grafts have gained considerable attention in the field of clinical research as they can be used to avoid re-surgery to remove scaffolds. We fabricated biodegradable composite ceramic scaffolds using magnesium oxide and calcium phosphate following the vat photopolymerization technology. We studied the effects of different magnesium oxide content on the process of in vitro degradation of the composite scaffolds and discussed the degradation process by comparing the extent of degradation realized in Tris-HCl buffer and simulated body fluids. We also explored the variations in the mechanical properties of the scaffolds during degradation. The results revealed that the composite scaffolds maintained the strength standard for spongy bone (compressive strength σ: 2–20 MPa) even after 28 d of degradation. Additionally, the strength of the composite scaffold containing 80 wt% magnesium oxide was comparable to the strength standard recommended for cortical bones (σ: 100–200 MPa). Controllable degradation rates were recorded, and acceptable mechanical properties were observed for these scaffolds during degradation. The results reported herein can be potentially used to expand the application prospects of biodegradable scaffolds.

Fabrication and Release Mechanism Study of a Nanocapsule Breaker for Controlling Degradation Rate of Insoluble Residue in Slickwater at Moderate-Temperature Reservoirs

Summary In an ideal hydraulic fracturing project, the viscosity of hydraulic fracturing fluid (HFF) should drop to facilitate an efficient and quick fracture cleanup once proppants have been placed. Ammonium persulfate (APS) is widely used as an oxidizer breaker to degrade the insoluble residue of the HFF. However, a complex network of artificial fractures with sizes ranging from millimeters to micrometers restricts the transportation application and reaction time of standard breakers and current millimeter-sized capsule breakers. In this study, we introduce an APS nanocapsule (APS-NC) breaker, fabricated via a simple miniemulsion technique, that is capable of addressing the degradation of insoluble residue of the HFF in deep fractures. The nanocapsules are produced through precise control of the nanoprecipitation of poly(methyl methacrylate) (PMMA) onto aqueous APS nanodroplets. Stable aqueous nanodroplets are generated by means of an inverse miniemulsion using Pluronic P-123 as a specific surfactant to form a large and stable water-oil internal surface referring to the long chain and amphipathic property of Pluronic P-123 molecule. Pluronic P-123 is included in the process not only to stabilize the miniemulsion and increase the precipitation efficiency of PMMA but also to function as a thermo-responsive switch for the delayed burst release of APS. The size of the resulting nanocapsules can be controlled within the 207 and 821 nm range, yielding APS up to 92%. The release rate of APS can be controlled by the initial amount of PMMA (150–300 mg), environmental temperature (40–80°C), and environmental pH (3.4–7). When the temperature was 80℃, the initial amount of Pluronic P-123 dominated the release dynamic of APS. Compared with the APS breaker in a dynamic degradation experiment, the APS-NC had a more controllable degradation profile that could cause hydrolyzed polyacrylamide (HPAM) to burst degrade after 6 hours of heating at 80°C.

Fabrication and evaluation of 3D printed poly(l-lactide) copolymer scaffolds for bone tissue engineering

The application of poly(L-lactic acid) (PLLA) in tissue engineering is limited due to its brittleness and uncontrollable degradation rate. In this study, the flexible p-dioxanone (PDO) and highly reactive glycolide (GA) units were introduced into PLLA segments by chemical modification to prepare poly(l-lactide-ran-p-dioxanone-ran-glycolide) (PLPG) copolymers. The copolymers were then processed into the PLPG scaffold by a 3D printing technology. The physicochemical properties of the PLPG copolymers were studied by NMR, DSC, XRD, GPC, and SEM. Furthermore, the mechanical properties, degradation properties, and biocompatibility of the PLPG scaffolds were also studied. The results showed that introducing PDO and GA units disrupted the regularity of PLLA, decreasing the crystallinity of the PLPG copolymers. However, introducing PDO and GA units could effectively improve the mechanical and degradation properties of the PLLA scaffolds. In vitro cell culture experiments indicated that the PLPG scaffolds supported proliferation, growth, and differentiation of MC3T3-E1 cells. The PLPG scaffolds reported herein, with controllable degradation rates and mechanical performance, may find applications in bone tissue engineering.

Controllable Water-Triggered Degradation of PCL Solution-Blown Nanofibrous Webs Made Possible by Lipase Enzyme Entrapment

Polymers in nanofibrous forms offer new opportunities for achieving triggered polymer degradation, which is important for functional and environmental reasons. The polycaprolactone (PCL) nanofibrous nonwoven polymer webs developed in this work by solution blow spinning with entrapped enzymes were completely, rapidly and controllably degraded when triggered by exposure to water. Lipase (CALB) from Candida antarctica was successfully entrapped in the PCL webs via an enzyme-compatible water-in-oil emulsion in the PCL–chloroform spinning solution with added surfactant. Protein (enzyme) in the nanofibrous webs was detected by Fourier Transform Infrared Spectroscopy (FTIR), while time of flight-secondary ion mass spectroscopy (ToF-SIMS) and laser confocal microscopy indicated that enzymes were immobilized within solid fibers as well as within microbead structures distributed throughout the webs. Degradation studies of CALB-enzyme functionalized solution-blown nonwoven (EFSBN)-PCL webs at 40 °C or ambient temperature showed that EFSBN-PCL webs degraded rapidly when exposed to aqueous pH 8 buffer. Scanning electron microscopy (SEM) images of partially degraded webs showed that thinner fibers disappeared first, thus, controlling fiber dimensions could control degradation rates. Rapid degradation was attributed to the combination of nanofibrous web structure and the distribution of enzymes throughout the webs. CALB immobilized in the solid dry webs exhibited long storage stability at room temperature or when refrigerated, with around 60% catalytic activity being retained after 120 days compared to the initial activity. Dry storage stability at ambient conditions and rapid degradation upon exposure to water demonstrated that EFSBN-PCL could be used as fibers or binders in degradable textile or paper products, as components in packaging, for tissue engineering and for controlled-release drug or controlled-release industrial and consumer product applications.

Effect of the microstructure parameters on the corrosion characteristics of Mg-Zn-Ca alloy with columnar structure

Magnesium alloys with homogeneous degradation and controlled degradation rate are desirable for biodegradable materials. In the present work, Mg-3 wt.%Zn-0.2 wt.%Ca alloys with different columnar structures were fabricated and the degradation in 0.9 wt.% NaCl were investigated. With the increase of the growth rate for the directional solidification, the microstructure of the directionally solidified (DSed) alloy evolved from cellular to dendritic coupled with the change of the spacing of the primary trunks (λ1) and the volume fraction (fv) of Ca2Mg6Zn3 phase. The results of the corrosion test suggested that the alloy with cellular structure experienced homogeneous corrosion and exhibited the lowest corrosion rate. The good corrosion resistance of the alloy with cellular structure was attributed to the protective corrosion products film (CPF), which was closely related to the fv of Ca2Mg6Zn3 phase and λ1. To evaluate the corrosion rates (CR) of the DSed Mg-Zn-Ca alloys with different microstructures, a parameter α was proposed in this work, which was calculated by λ1 and the fv of Ca2Mg6Zn3 phase. The fitting result showed that there was a linear relationship between CR and α, which was CR = 4.1899 + 0.00432α. This means that the CR of the DSed Mg-Zn-Ca alloy can be evaluated if the microstructure had been characterized.

Injectable Self-Setting Ternary Calcium-Based Bone Cement Promotes Bone Repair.

Bone defects, especially large ones, are clinically difficult to treat. The development of new bone repair materials exhibits broad application prospects in the clinical treatment of trauma. Bioceramics are considered to be one of the most promising biomaterials owing to their good biocompatibility and bone conductivity. In this study, a self-curing bone repair material having a controlled degradation rate was prepared by mixing calcium citrate, calcium hydrogen phosphate, and semi-hydrated calcium sulfate in varying proportions, and its properties were comprehensively evaluated. In vitro cell experiments and RNA sequencing showed that the composite cement activated PI3K/Akt and MAPK/Erk signaling pathways to promote osteogenesis by promoting the proliferation and osteoblastic differentiation of mesenchymal stem cells. In a rat model with femoral condyle defects, the composite bone cement showed excellent bone repair effect and promoted bone regeneration. The injectable properties of the composite cement further improved its practical applicability, and it can be applied in bone repair, especially in the repair of irregular bone defects, to achieve superior healing.

Antibacterial and pH-sensitive methacrylate poly-L-Arginine/poly (β-amino ester) polymer for soft tissue engineering

During the last decade, pH-sensitive biomaterials containing antibacterial agents have grown exponentially in soft tissue engineering. The aim of this study is to synthesize a biodegradable pH sensitive and antibacterial hydrogel with adjustable mechanical and physical properties for soft tissue engineering. This biodegradable copolymer hydrogel was made of Poly-L-Arginine methacrylate (Poly-L-ArgMA) and different poly (β- amino ester) (PβAE) polymers. PβAE was prepared with four different diacrylate/diamine monomers including; 1.1:1 (PβAE1), 1.5:1 (PβAE1.5), 2:1 (PβAE2), and 3:1 (PβAE3), which was UV cross-linked using dimethoxy phenyl-acetophenone agent. These PβAE were then used for preparation of Poly-L-ArgMA/PβAE polymers and revealed a tunable swelling ratio, depending on the pH conditions. Noticeably, the swelling ratio increased by 1.5 times when the pH decreased from 7.4 to 5.6 in the Poly-L-ArgMA/PβAE1.5 sample. Also, the controllable degradation rate and different mechanical properties were obtained, depending on the PβAE monomer ratio. Noticeably, the tensile strength of the PβAE hydrogel increased from 0.10 ± 0.04 MPa to 2.42 ± 0.3 MPa, when the acrylate/diamine monomer molar ratio increased from 1.1:1 to 3:1. In addition, Poly-L-ArgMA/PβAE samples significantly improved L929 cell viability, attachment and proliferation. Poly-L-ArgMA also enhanced the antibacterial activities of PβAE against both Escherichia coli (~5.1 times) and Staphylococcus aureus (~2.7 times). In summary, the antibacterial and pH-sensitive Poly-L-ArgMA/PβAE1.5 with suitable mechanical, degradation and biological properties could be an appropriate candidate for soft tissue engineering, specifically wound healing applications.Graphical

The effects of boron trioxide on the structure and degradation behaviour of borosilicate bioactive glass

ABSTRACT Degradation behaviour of bioactive glass (bioglass) is one of the most important factors affecting bone repair, because an excellent and controllable degradation rate can match the rate of new bone formation. In this research, the derived borosilicate bioglasses based on the 6Na2O-8K2O-8MgO-22CaO-18B2O3-54SiO2-2P2O5 component were synthesized. The effects of B2O3 on the structure, degradation behaviour and cytocompatibility of borosilicate bioglasses were systematically studied. The results showed that with B2O3 addition, the network-forming units became diversified and part of BO4 units transformed into BO3 units. These factors weakened the chemical durability of borosilicate bioglass, thus accelerating the bioglass shedding and altering the ions release, especially B. This study provides a theoretical basis for designing borosilicate bioglass with adjustable degradation rate and ion release behaviour to meet the diverse needs of clinical bone repair.

Microstructural and Electrochemical Influence of Zn in MgCaZn Biodegradable Alloys.

In recent years, biodegradable materials have included magnesium alloys with homogenous disintegration and a controllable degradation rate. Utilized in medical applications, biodegradable materials based on magnesium have been widely explored throughout the years. It is well-known that alloying Mg with biocompatible and non-toxic elements increases the biodegradability of surgical alloys. The purpose of this study was to examine the microstructure and the electrochemical response (corrosion resistance) of a new experimental Mg-based biodegradable alloy-Mg-0.5%Ca with additions of Zn as follows: 0.5, 1.5, and 3.0 wt.% in order to control the corrosion rate. Immersion tests were performed for different periods in a simulated body fluid electrolyte solution at 37 °C, and the mass loss was appreciated in order to calculate the corrosion rate (CR). The investigation led to the discovery of a dendritic Mg solid solution, a lamellar Mg2Ca compound, and a MgZn2 intermetallic phase. Scanning electron microscopy, optical microscopy, and energy dispersive spectroscopy were used for surface analysis after the immersion and electro-corrosion resistance tests. The metallic and ceramic compounds that detached themselves from the sample and passed into the solution were evaluated using the SEM-EDS system. All samples presented a generalized electro-corrosion with anodic and cathodic reactions of similar intensity. The corrosion rate was similar regardless of the percentage of zinc, with a smaller value for a higher than 3 wt.% Zn percentage based on the more protective zinc oxide that appeared on the surface.

Photocrosslinkable, Injectable Locust Bean Gum Hydrogel Induces Chondrogenic Differentiation of Stem Cells for Cartilage Regeneration.

Due to the limited therapeutic efficacy of current treatments, articular cartilage regeneration is still challenging work. Scaffold-based tissue engineering provides a promising strategy for cartilage regeneration, but most scaffolds are limited by poor mechanical properties or unfavorable biocompatibility. Here, a novel photocrosslinkable, injectable locust bean gum (LBG)-methacrylate (MA) hydrogel is reported as a biomimetic extracellular matrix (ECM) for cartilage repair with minimal invasive operation. LBG-MA hydrogels show controllable degradation rate and improve mechanical properties and excellent biocompatibility. More importantly, LBG-MA hydrogel significantly induces bone mesenchymal stem cells to chondrogenic differentiation in vitro, as evidenced by high accumulation of cartilage-specific ECM components glycosaminoglycan and upregulated expression of key chondrogenic genes (collagen type II, aggrecan, and sex determining region Y-box9). Besides, the hydrogel is injectable, which can be in situ crosslinked via UV irradiation. Further, the photocrosslinkable hydrogels accelerate cartilage healing in vivo after 8 weeks of therapy. A strategy is provided here for photocrosslinkable, injectable, biodegradable scaffold fabrication based on native polysaccharide polymer for minimal invasive cartilage repair.

A review of recent advances on osteogenic applications of Silk fibroin as a potential bio-scaffold in bone tissue engineering

Silk fibroin (SF) have been increasingly used as bone substitutes in tissue engineering (TE) due to their sufficient mechanical strength, good biocompatibility, osteoconductive, and controllable degradation rates. The SF scaffold as a 3D-matrix allows and stimulates the proliferation, attachment and differentiation of stem cells toward osteogenic cells. Herein, we have summarized the applications of SF for regeneration of bone defects in a comprehensive manner. Additionally, we have discussed three critical factors for osteogenesis regulation, including biological (cells and growth factors), physical (mechanics and morphology), and chemical (composition) aspects with their current drawbacks and future perspective of SF in bone TE.

Multifunctional Scaffold for Osteoporotic Pathophysiological Microenvironment Improvement and Vascularized Bone Defect Regeneration.

Osteoporosis is a degenerative bone disease resulting from bone homeostasis imbalance regulated by osteoblasts and osteoclasts. Treating osteoporotic bone defects tends to be more difficult due to suppressed osteogenic differentiation, hyperactive osteoclastogenesis, and impaired angiogenesis. Hence, a drug carrier system composed of gelatin-coated hollow mesoporous silica nanoparticles (HMSNs/GM) loaded with pro-osteogenic parathyroid (PTH) and anti-osteoclastogenic alendronate (ALN) is constructed and compounded into calcium magnesium phosphate cement (MCPC). The spatial-temporal release of ions and drugs, controllable degradation rate, and abundant pore structure of MCPC composites enhance osteoporotic bone regeneration in ovariectomized rats by accelerating vascularization, promoting osteogenic differentiation and mineralization, and inhibiting osteoclastogenesis and bone resorption. The MCPC/HMSNs@ALN-PTH/GM demonstrates a synergistic threefold effect on osteogenesis, osteoclastogenesis, and angiogenesis. It improves the osteoporotic pathophysiological microenvironment and promotes osteoporotic vascularized bone defect regeneration, holding huge potential for other functional biomaterials design and clinical management.

3D-Printing of Silk Nanofibrils Reinforced Alginate for Soft Tissue Engineering.

The main challenge of extrusion 3D bioprinting is the development of bioinks with the desired rheological and mechanical performance and biocompatibility to create complex and patient-specific scaffolds in a repeatable and accurate manner. This study aims to introduce non-synthetic bioinks based on alginate (Alg) incorporated with various concentrations of silk nanofibrils (SNF, 1, 2, and 3 wt.%) and optimize their properties for soft tissue engineering. Alg-SNF inks demonstrated a high degree of shear-thinning with reversible stress softening behavior contributing to extrusion in pre-designed shapes. In addition, our results confirmed the good interaction between SNFs and alginate matrix resulted in significantly improved mechanical and biological characteristics and controlled degradation rate. Noticeably, the addition of 2 wt.% SNF improved the compressive strength (2.2 times), tensile strength (5 times), and elastic modulus (3 times) of alginate. In addition, reinforcing 3D-printed alginate with 2 wt.% SNF resulted in increased cell viability (1.5 times) and proliferation (5.6 times) after 5 days of culturing. In summary, our study highlights the favorable rheological and mechanical performances, degradation rate, swelling, and biocompatibility of Alg-2SNF ink containing 2 wt.% SNF for extrusion-based bioprinting.

Substrate controlled degradation rate of protective SiAlN coating via mitigating interfacial reaction

The degradation rates of protective SiAlN coatings (0.9 µm thick) on pure Ti, Ti6Al4V, and Timetal 834 alloys in air at 800 °C were investigated and compared. The SiAlN coating on pure Ti was depleted and then formed a thin oxide scale after exposure of 50 h, whereas a 0.6 µm thick remnant SiAlN coating without any signs of oxidation was observed on Timetal 834. Interfacial reactions between SiAlN coatings and different substrates caused depletion of SiAlN, thereby determining the degradation rates of SiAlN coatings. The non-reactive alloying elements Sn and Al in Timetal 834 alloy could retard such interfacial reactions, thereby impeding coating degradation.

Fibrin sealant as a delivery vehicle for cells, antibiotics, growth factors, and painkillers

Fibrin sealant has vast uses in surgical settings for both cellular and noncellular delivery. Some advantages include biocompatibility, ability to support cell attachment, and controlled degradation rate. There are many clinical applications, from wound healing to improving bone defects to being used as an adjunct to surgery. It can also serve as a suitable delivery vehicle for cells, steroids, antibiotics, growth factors, chemotherapeutic agents, and painkillers. The composition of fibrin sealant can be altered to allow for controlled release, making it an attractive delivery system. Lastly, a wound healing model with 2 defects in the collagen construct may serve as a future application that utilizes fibrin sealant as a delivery system. This review highlights different uses of fibrin sealant as a delivery vehicle for cells, steroids, antibiotics, chemotherapeutic agents, growth factors, and painkillers