Controllable Degradation Rate Research Articles

Biocomposite Scaffolds for Tissue Engineering: Materials, Fabrication Techniques and Future Directions

Tissue engineering is an interdisciplinary field that combines materials, methods, and biological molecules to engineer newly formed tissues to replace or restore functional organs. Biomaterials-based scaffolds play a crucial role in developing new tissue by interacting with human cells. Tissue engineering scaffolds with ideal characteristics, namely, nontoxicity, biodegradability, and appropriate mechanical and surface properties, are vital for tissue regeneration applications. However, current biocomposite scaffolds face significant limitations, particularly in achieving structural durability, controlled degradation rates, and effective cellular integration. These qualities are essential for maintaining long-term functionality in vivo. Although commonly utilized biomaterials can provide physical and chemical properties needed for tissue regeneration, inadequate biomimetic properties, as well as insufficient interactions of cells-scaffolds interaction, still need to be improved for the application of tissue engineering in vivo. It is impossible to achieve some essential features using a single material, so combining two or more materials may accomplish the requirements. In order to achieve a proper scaffold design, a suitable fabrication technique and combination of biomaterials with controlled micro or nanostructures are needed to achieve the proper biological responses. This review emphasizes advancements in scaffold durability, biocompatibility, and cellular responsiveness. It focuses on natural and synthetic polymer combinations and innovative fabrication techniques. Developing stimulus-responsive 3D scaffolds is critical, as these scaffolds enhance cell adhesion and promote functional tissue formation while maintaining structural integrity over time. This review also highlights the natural polymers, smart materials, and recent advanced techniques currently used to create emerging scaffolds for tissue regeneration applications.

Application of Polylactic Acid in Clinical Medicine

Polylactic acid (PLA), a bio-based and biodegradable material, shows significant potential in environmental protection and clinical medicine. Derived from renewable resources, PLA's biodegradability reduces long-term environmental pollution by allowing it to decompose rapidly under specific conditions. This review explores PLA's applications in clinical medicine, emphasizing its mechanical properties, biocompatibility, and controlled degradation rates. The study covers PLA's extensive use in drug delivery systems, absorbable sutures, and tissue engineering scaffolds, highlighting its compatibility with human tissues and low immunogenicity. Research methods and designs, including in vitro and in vivo experiments, are discussed to evaluate PLA's efficacy and safety. The challenges of high production costs and specific degradation conditions are also addressed. Future research directions include developing new catalysts to improve synthesis efficiency and exploring renewable raw materials to reduce costs and environmental impact. As global awareness of sustainable development grows, the demand for PLA and other degradable plastics is expected to increase, expanding their applications in various fields. In conclusion, PLA offers substantial advantages in reducing reliance on fossil fuels and mitigating environmental pollution, while providing innovative solutions in the medical field. Technological advancements and increased production are anticipated to lower costs, making PLA more economically competitive and accelerating its application in both environmental protection and clinical medicine.

Predicting synthetic mRNA stability using massively parallel kinetic measurements, biophysical modeling, and machine learning.

mRNA degradation is a central process that affects all gene expression levels, though it remains challenging to predict the stability of a mRNA from its sequence, due to the many coupled interactions that control degradation rate. Here, we carried out massively parallel kinetic decay measurements on over 50,000 bacterial mRNAs, using a learn-by-design approach to develop and validate a predictive sequence-to-function model of mRNA stability. mRNAs were designed to systematically vary translation rates, secondary structures, sequence compositions, G-quadruplexes, i-motifs, and RppH activity, resulting in mRNA half-lives from about 20 seconds to 20 minutes. We combined biophysical models and machine learning to develop steady-state and kinetic decay models of mRNA stability with high accuracy and generalizability, utilizing transcription rate models to identify mRNA isoforms and translation rate models to calculate ribosome protection. Overall, the developed model quantifies the key interactions that collectively control mRNA stability in bacterial operons and predicts how changing mRNA sequence alters mRNA stability, which is important when studying and engineering bacterial genetic systems.

Alginate-gelatin based nanocomposite hydrogel scaffold incorporated with bioactive glass nanoparticles and fragmented nanofibers promote osteogenesis: From design to in vitro studies

The current study proposes fragmented nanofibers of polycaprolactone (FNF) with bioactive glass nanoparticles (nBG) incorporated into a polymeric matrix of alginate-gelatin for the creation of a hydrogel scaffold. Four groups were prepared: control, bioactive glass containing scaffold (BG), fragmented nanofibers with bioactive glass scaffold (FNF(PCL) + BG), and fragmented composite nanofibers scaffold (FNF (PCL + BG)). FNF (PCL + BG) scaffolds revealed a more controlled degradation rate, with approximately 20 % degradation occurring after 28 compared. The FNF(PCL) + BG scaffolds had the highest compressive strength in both dry and wet states. Following 14 days of incubation in simulated body fluid, hydroxyapatite formation had occurred on the surface of scaffolds containing nBG, and after 28 days on other groups tested. Cell studies revealed that the FNF(PCL) + BG scaffolds had superior cell viability without inhibiting cell proliferation. The FNF(PCL) + BG and FNF(PCL + BG) scaffolds had the highest alkaline phosphatase (ALP) activity and FNF(PCL) + BG scaffolds showed to support osteogenic differentiation.

Swelling Induced Hardening and Degradation Induced Slow-Expansion Hydrogel for a Modified Cervical Spinal Cord Compression Animal Model.

This study presents the development of a polyurethane hydrogel (PUG) for use in a chronic cervical spinal cord compression animal model, leveraging microphase separation and dynamic covalent bonds to achieve swelling induced hardening and degradation-induced slow expansion. PUG-SS and PUG-SS-60% were synthesized with varying disulfide bond concentrations, offering controllable degradation rates and mechanical properties. The hydrogels demonstrated significant swelling-induced hardening and maintained compression above the cervical spinal cord's intrinsic modulus. MRI and histopathological analyses confirmed effective and sustained spinal cord compression, with PUG-SS-60% showing prolonged effects. Behavioral tests, including the BBB locomotor scale, von Frey pain test, and catwalk gait analysis, indicated quicker motor function recovery with PUG-SS and sustained compression with PUG-SS-60%. In vitro cytotoxicity assays showed no significant hydrogel-induced cell death. This study underscores the potential of PUG-SS-60% for providing controlled, sustained compression in chronic spinal cord compression models, paving the way for advanced nonsurgical treatment strategies and improved understanding of degenerative cervical myelopathy (DCM) pathology.

Analysis of mixed traffic flow characteristics based on cellular automata model under lane management measures

In the future, mixed traffic flow comprising Human-Driven Vehicles (HDVs), Connected and Autonomous Vehicles (CAVs), and CAV platoons will coexist for an extended period. Exploring the operational characteristics of mixed traffic flow under different lane management measures is essential for effective management and control. Initially, we analyze the motion characteristics of HDVs, CAVs, and CAV platoons and identify the car-following types within mixed traffic. Based on vehicle motion characteristics and the variance in maximum desired speeds among HDV drivers, we establish longitudinal motion rules for HDVs using a safety distance model. For CAVs and their platoons, we develop longitudinal motion rules by considering platoon merging and splitting behaviors, as well as speed and spacing error requirements for platoon driving. Subsequently, we formulate lateral lane-change rules based on the Symmetric Two-lane Cellular Automata (STCA) model, considering differences in reaction times and following distances between HDVs and CAVs. Finally, we conducted simulation experiments on a unidirectional three-lane highway using the multi-lane mixed traffic flow cellular automata model, analyzing the characteristics of mixed traffic under various lane management measures, such as mixed lane, CAV-dedicated lane, and CAV-priority lane. The results show that as the proportion of CAV (denoted as p) increases, the traffic flow capacity, optimal density, and jam density also increase. When p≤0.6, the k−q diagram exhibits a triangular shape, whereas for p>0.6, it assumes a trapezoidal shape. Implementing CAV-dedicated lane can reduce Cooperative Adaptive Cruise Control (CACC) degradation rates but only enhances traffic flow capacity when the CAV proportion reaches a certain threshold. Compared to the mixed lane scheme, when p≤0.3 and k≤0.3, the CAV-priority lane schemes not only meet traffic demands but also reduce CACC degradation rates. The vehicle speed in CAV-priority lane surpasses that in HDV lanes, facilitating improved traffic efficiency for CAVs. The distribution of maximum speeds among HDV drivers affects the fundamental diagram of mixed traffic flow and the performance of CAV-priority lane, with greater impacts observed as the standard deviation of the HDVs' maximum speed increases.

A Review of the Development of Titanium-Based and Magnesium-Based Metallic Glasses in the Field of Biomedical Materials.

This article reviews the research and development focus of metallic glasses in the field of biomedical applications. Metallic glasses exhibit a short-range ordered and long-range disordered glassy structure at the microscopic level, devoid of structural defects such as dislocations and grain boundaries. Therefore, they possess advantages such as high strength, toughness, and corrosion resistance, combining characteristics of both metals and glasses. This novel alloy system has found applications in the field of biomedical materials due to its excellent comprehensive performance. This review discusses the applications of Ti-based bulk metallic glasses in load-bearing implants such as bone plates and screws for long-term implantation. On the other hand, Mg-based metallic glasses, owing to their degradability, are primarily used in degradable bone nails, plates, and vascular stents. However, metallic glasses as biomaterials still face certain challenges. The Young's modulus value of Ti-based metallic glasses is higher than that of human bones, leading to stress-shielding effects. Meanwhile, Mg-based metallic glasses degrade too quickly, resulting in the premature loss of mechanical properties and the formation of numerous bubbles, which hinder tissue healing. To address these issues, we propose the following development directions: (1) Introducing porous structures into titanium-based metallic glasses is an important research direction for reducing Young's modulus; (2) To enhance the bioactivity of implant material surfaces, the surface modification of titanium-based metallic glasses is essential. (3) Developing antibacterial coatings and incorporating antibacterial metal elements into the alloys is essential to maintain the long-term effective antibacterial properties of metallic biomaterials. (4) Corrosion resistance must be further improved through the preparation of composite materials, while ensuring biocompatibility and safety, to achieve controllable degradation rates and degradation modes.

Analysis of the CPZ/Wnt4 osteogenic pathway for high-bonding-strength composite-coated magnesium scaffolds through transcriptomics

Magnesium (Mg)-based scaffolds are garnering increasing attention as bone repair materials owing to their biodegradability and mechanical resemblance to natural bone. Their effectiveness can be augmented by incorporating surface coatings to meet clinical needs. However, the limited bonding strength and unclear mechanisms of these coatings have impeded the clinical utility of scaffolds. To address these issues, this study introduces a composite coating of high-bonding-strength polydopamine-microarc oxidation (PDA-MHA) on Mg-based scaffolds. The results showed that the PDA-MHA coating achieved a bonding strength of 40.56 ± 1.426 MPa with the Mg scaffold surface, effectively enhancing hydrophilicity and controlling degradation rates. Furthermore, the scaffold facilitated bone regeneration by influencing osteogenic markers such as RUNX-2, OPN, OCN, and VEGF. Transcriptomic analyses further demonstrated that the PDA-MHA/Mg scaffold upregulated carboxypeptidase Z expression and activated the Wnt-4/β-catenin signaling pathway, thereby promoting bone regeneration. Overall, this study demonstrated that PDA can synergistically enhance bone repair with Mg scaffold, broadening the application scenarios of Mg and PDA in the field of biomaterials. Moreover, this study provides a theoretical underpinning for the application and clinical translation of Mg-based scaffolds in bone tissue engineering endeavors.

Research on a new type of ureteral stent material Zn-2Cu-0.5Fe-xMn with controllable degradation rate

The placement of ureteral stents plays a crucial role in the treatment of ureteral strictures, therefore requiring high material performance standards. In addition, depending on the etiology of ureteral strictures, there are significant differences in the retention time of ureteral stents, thus requiring different degradation rates for the stents. Therefore, it is crucial to develop stent materials with high performance and controllable degradation rates. This study explores the potential of Zn-2Cu-0.5Fe-xMn alloy as a ureteral stent material, utilizing the antibacterial effect of copper ions, the strengthening effect of Fe element on Zn-based alloys, and the accelerated degradation effect of Mn element. The research found that with the increase in Mn content, the average grain size of the alloy and the size of (Fe, Mn)Zn13 phase gradually increased, leading to a decrease in hardness. The corrosion rate of the alloy increased with the increase in Mn content, attributed to changes in grain size and standard electrode potential differences between elements. Due to the antibacterial effects of Zn ions and Cu ions, the Zn-2Cu-0.5Fe-xMn alloy exhibits good anti-stone formation capabilities. Furthermore, the alloy also demonstrates acceptable cytotoxicity. Therefore, the Zn-2Cu-0.5Fe-xMn alloy is expected to become an important implant material in urological surgery.

Coaxial Bioprinting of Enzymatically Crosslinkable Hyaluronic Acid-Tyramine Bioinks for Tissue Regeneration.

Three-dimensional (3D) bioprinting has emerged as an important technique for fabricating tissue constructs with precise structural and compositional control. However, developing suitable bioinks with biocompatible crosslinking mechanisms remains a significant challenge. This study investigates extrusion-based bioprinting (EBB) using uniaxial or coaxial nozzles with enzymatic crosslinking (EC) to produce 3D tissue constructs in vitro. Initially, low-molecular-weight dextran-tyramine and hyaluronic acid-tyramine (LMW Dex-TA/HA-TA) bioink prepolymers were evaluated. Enzymatically pre-crosslinking these prepolymers, achieved by the addition of horseradish peroxidase and hydrogen peroxide, produced viscous polymer solutions. However, this approach resulted in inconsistent bioprinting outcomes (uniaxial) due to inhomogeneous crosslinking, leading to irreproducible properties and suboptimal shear recovery behavior of the hydrogel inks. To address these challenges, we explored a one-step coaxial bioprinting system consisting of enzymatically crosslinkable high-molecular-weight hyaluronic acid-tyramine conjugates (HMW HA-TA) mixed with horseradish peroxidase (HRP) in the inner core and a mixture of Pluronic F127 and hydrogen peroxide in the outer shell. This configuration resulted in nearly instantaneous gelation by diffusion of the hydrogen peroxide into the core. Stable hydrogel fibers with desirable properties, including appropriate swelling ratios and controlled degradation rates, were obtained. The optimized bioink and printing parameters included 1.3% w/v HMW HA-TA and 5.5 U/mL HRP (bioink, inner core), and 27.5% w/v Pluronic F127 and 0.1% H2O2 (sacrificial ink, outer shell). Additionally, optimal pressures for the inner core and outer shell were 45 and 80 kPa, combined with a printing speed of 300 mm/min and a bed temperature of 30 °C. The extruded HMW HA-TA core filaments, containing bovine primary chondrocytes (BPCs) or 3T3 fibroblasts (3T3 Fs), exhibited good cell viabilities and were successfully cultured for up to seven days. This study serves as a proof-of-concept for the one-step generation of core filaments using a rapidly gelling bioink with an enzymatic crosslinking mechanism, and a coaxial bioprinter nozzle system. The results demonstrate significant potential for developing designed, printed, and organized 3D tissue fiber constructs.

Magnetically responsive micro-clustered calcium phosphate-reinforced cell-laden microbead sodium alginate hydrogel for accelerated osteogenic tissue regeneration

The rising prevalence of bone injuries has increased the demand for minimally invasive treatments. Microbead hydrogels, renowned for cell encapsulation, provide a versatile substrate for bone tissue regeneration. They deliver bioactive agents, support cell growth, and promote osteogenesis, aiding bone repair and regeneration. In this study, we synthesized superparamagnetic iron oxide nanoparticles (Sp) coated with a calcium phosphate layer (m-Sp), achieving a distinctive flower-like micro-cluster morphology. Subsequently, sodium alginate (SA) microbead hydrogels containing m-Sp (McSa@m-Sp) were fabricated using a dropping gelation strategy. McSa@m-Sp is magnetically targetable, enhance cross-linking, control degradation rates, and provide strong antibacterial activity. Encapsulation studies with MC3T3-E1 cells revealed enhanced viability and proliferation. These studies also indicated significantly elevated alkaline phosphatase (ALP) activity and mineralization in MC3T3-E1 cells, as confirmed by Alizarin Red S (ARS) and Von Kossa staining, along with increased collagen production within the McSa@m-Sp microbead hydrogels. Immunocytochemistry (ICC) and gene expression studies supported the osteoinductive potential of McSa@m-Sp, showing increased expression of osteogenic markers including RUNX-2, collagen-I, osteopontin, and osteocalcin. Thus, McSa@m-Sp microbead hydrogels offer a promising strategy for multifunctional scaffolds in bone tissue engineering.

PCL reinforced nano strontium hydroxyapatite-Butea monosperma-scaffold for bone regeneration

Biocomposite materials, composed of biodegradable polymers and supplements, are promising for bone regenerative matrices due to their mechanical strength and excellent osteoconductivity. This study focuses on fabricating electrospun composite scaffolds using the bark extract of Butea monosperma (BM), nano strontium hydroxyapatite (nSrHA), and polycaprolactone (PCL). Four types of scaffolds were prepared: PCL (control), BM-PCL, nSrHA-PCL, and BM-nSrHA-PCL. The scaffolds were evaluated through various techniques: bright field microscopy for standardization, SEM for structural evaluation, and SEM-EDX for elemental analysis. Additionally, mechanical strength, release study, degradation, and protein adsorption were assessed. Furthermore, cytotoxicity, proliferation, and cytocompatibility of the scaffolds were evaluated using rat adipose-derived mesenchymal stem cells (rADMSCs) through SEM, MTT assay, LDH assay, DAPI staining, and Direct contact assay. SEM analysis confirmed that all four fabricated scaffolds were nano-fibrous in nature. The incorporation of phytochemicals and nSrHA was confirmed via SEM-EDX. Mechanical testing revealed that the BM-nSrHA-PCL scaffolds had superior mechanical properties compared to the control PCL scaffolds. Protein adsorption studies indicated enhanced protein binding in BM-nSrHA-PCL scaffolds. Degradation studies showed that BM-nSrHA-PCL scaffolds had a controlled degradation rate suitable for tissue engineering applications. Cytotoxicity tests confirmed that all scaffolds were noncytotoxic. Proliferation and cytocompatibility assays demonstrated that BM-nSrHA-PCL scaffolds significantly promoted cell proliferation compared to other scaffold types. These results suggest that the BM-nSrHA-PCL scaffolds exhibit improved mechanical properties, protein adsorption, controlled degradation, and enhanced cell proliferation, making them promising candidates for bone tissue engineering applications.

Injectable Biomimetic Gels for Biomedical Applications.

Biomimetic gels are synthetic materials designed to mimic the properties and functions of natural biological systems, such as tissues and cellular environments. This manuscript explores the advancements and future directions of injectable biomimetic gels in biomedical applications and highlights the significant potential of hydrogels in wound healing, tissue regeneration, and controlled drug delivery due to their enhanced biocompatibility, multifunctionality, and mechanical properties. Despite these advancements, challenges such as mechanical resilience, controlled degradation rates, and scalable manufacturing remain. This manuscript discusses ongoing research to optimize these properties, develop cost-effective production techniques, and integrate emerging technologies like 3D bioprinting and nanotechnology. Addressing these challenges through collaborative efforts is essential for unlocking the full potential of injectable biomimetic gels in tissue engineering and regenerative medicine.

Effect of graphite, graphene oxide, and multi-walled carbon nanotubes on the physicochemical characteristics and biocompatibility of chitosan/hyaluronic acid/hydroxyapatite scaffolds for tissue engineering applications

Bone tissue engineering (BTE) is a promising alternative approach to the repair of damaged bone tissue. This study aims to fabricate and characterize scaffolds composed of chitosan (CS), hyaluronic acid (HA), hydroxyapatite (HAp), and a combination of graphite (Gr), graphene oxide (GO), and multi-walled carbon nanotubes (MWCNT) for BTE applications. The Gr and MWCNT were functionalized by acid oxidation, while the GO was synthesized using the improved Hummers' method. The scaffolds were prepared by lyophilization, and the physical, chemical, and biological properties were evaluated. Scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy, mechanical testing, water contact angle, degradation, and biocompatibility assays were used to characterize the scaffolds. The degradation rate was determined using the liquid displacement method. Pores of different sizes were present on the surface of and throughout the scaffold. According to the FTIR results, the scaffolds contained functional groups that promote cell differentiation and proliferation. These scaffolds have compressive strength, Young's modulus, and toughness similar to cancellous bone, with reasonable porosity and controllable degradation rates. Biocompatibility testing confirmed that the scaffolds support cell proliferation and differentiation.

Chitosan and neem gum-based polyelectrolyte complex for design of allantoin loaded biocomposite film: In-vitro, ex-vivo, and in-vivo characterization

Presently, the preference for chitosan (CS) and gum polysaccharides in biomedical applications including drug delivery and wound healing has been extensively documented. Despite this, the demerits of CS and gum polysaccharides such as poor mechanical properties, degradation rate, swelling, etc., limit their applications for designing biocomposite films for drug delivery. Therefore, the anticipated work aims to design a CS and neem gum polysaccharides (NGP) polyelectrolyte complex-based allantoin (AT)-loaded (CS/NGP-AT) biocomposite film for improved wound healing. In brief, CS, NGP, and CS/NGP-AT-based biocomposite films were prepared using the solvent-casting method, and in-vitro, ex-vivo, and in-vivo characterizations were performed to assess the performance of these biocomposite films compared to their counterparts. In this, diffractogram and thermogram analysis assured the conversion of crystalline AT into an amorphous form. The optimized CS/NGP/AT-3 formulation exhibited controlled water absorption, appropriate water uptake capacity, good water retention ability, excellent water vapor transmission rate, controlled degradation rate, enhanced mechanical properties, cell and blood biocompatibility, etc. Furthermore, it offered improved antimicrobial, anti-inflammatory, and antioxidant potential. The optimized film provided a modified release (88.3 ± 0.3 %) of AT from the film for up to 48 h. Wound healing experiments on rats and their histopathology studies confirmed a significantly higher rate of wound recovery within 14 days compared to the control and CS/NGP film, attributable to the combined effects of CS, NGP, and AT. In conclusion, the fabricated CS/NGP-based biocomposite film presents promising prospects as an excellent candidate for wound healing applications.

Study on the degradation of hydroxypropyl methylcellulose‐modified magnesium phosphate cement in different solutions

AbstractMagnesium phosphate bone cement (MPBC) is a bone repair material that has been extensively studied. For better availability of clinical medicine, its degradation rate needs to be effectively controlled. Hydroxypropyl methylcellulose (HPMC) has often been used as a drug carrier for controlled drug release. This property was utilized to influence the release kinetics of MPBC. This work investigated the degradation mechanism of MPBC controlled by HPMC. It was found that MPBC samples with 3 wt. % HPMC had the optimal properties. In this case, the setting time was 11 min and the maximum strength was 63.9 ± 2.5 MPa. The study found HPMC primarily controlled the degradation of MPBC hydration products via the combined actions of gradual diffusion, and release of MPBC hydration products, which subsequently caused the swelling, corrosion, and dissolution of the HPMC skeleton. Besides, the results showed that HPMC‐modified MPBC has good bioactivity, which is beneficial to bone repair. This bioactive HPMC‐modified MPBC showed a controllable degradation rate and proper mechanic properties, which may be applied to bone repair.

Exploring the utilization of polylactic acid-based materials in medicine: Contemporary innovations and trends

A biocompatible, non-toxic substance is polylactic acid (PLA), which is also biodegradable. This material has been studied for decades and has been commercially used in some fields. The potential of defined PLA for different medical applications, including drug delivery systems, wound healing, bone implants, and vascular grafts, was described in this paper. Various methods of characterization and modification of PLA have been investigated to optimize its properties for specific applications. Typically, additional polymers are introduced into PLA to enhance its functional properties. The key feature of PLA is its capacity for degradation in the human body without introducing harmful byproducts. Adjustments to PLA composition can control degradation rates, influencing drug delivery or the persistence of implants. By applying a cold plasma treatment in order to alter the PLA-based polymer's surface, the capacity of the material to transport drugs may be changed. The change of parameters in coaxial electrospinning can produce different PLA-based products for different use. However, certain challenges remain, such as improving the adhesion of PLA and production of low-price PLA.

Biocompatible implants in orthopedics: bone tissue engineering

Introduction Technological advances in bone tissue engineering have improved orthopaedic implants and surgical techniques for bone reconstruction. This approach allows overcoming inconvenience of the paucity of autologous materials available and donor site morbidity.Aim To demonstrate advances of the past 30 years in the development of bioimplants providing alternatives to bone grafting in reconstructive orthopaedics.Methods Preparing the review, the scientific platforms such as PubMed, Scopus, ResearchGate, RSCI were used for information searching. Search words or word combinations were bioactive osteoinductive implants, bone grafting, bone reconstruction, hydroxyapatite, bone scaffolds.Results The main trends in tissue engineering in the field of orthopaedics are represented by construction of three-dimensional structure implants guiding cell migration, proliferation and differentiation as well as mechanical support. Association with bone morphogenetic proteins, growth factors enables proliferation and differentiation of cell types of the targeted bone tissue. A promising advancement should be biodegradability with a controllable degradation rate to compliment cell/tissue in-growth and maturation in limb reconstruction.Discussion This review presents and discusses the experimental and clinical application of biotolerant, bioinert and bioactive materials for reconstructive bone surgery. Future generations of biomaterials are designed to be osteoconductive and osteoinductive.Conclusion Properties of polycaprolactone (PCL) filled with hydroxyapatite (from 10 to 50 wt %) make this hybrid material with controllable absorption a promising strategy for reconstructive surgery in comparison to other materials.

Hierarchical Hybrid Coatings with Drug-Eluting Capacity for Mg Alloy Biomaterials.

A hierarchical hybrid coating (HHC) comprising a ceramic oxide layer and two biodegradable polymeric (polycaprolactone, PCL) layers has been developed on Mg3Zn0.4Ca cast alloy in order to provide a controlled degradation rate and functionality by creating a favorable porous surface topography for cell adhesion. The inner, ceramic layer formed by plasma electrolytic oxidation (PEO) has been enriched in bioactive elements (Ca, P, Si). The intermediate PCL layer sealed the defect in the PEO layer and the outer microporous PCL layer loaded with the appropriate active molecule, thus providing drug-eluting capacity. Morphological, chemical, and biological characterizations of the manufactured coatings loaded with ciprofloxacin (CIP) and paracetamol (PAR) have been carried out. In vitro assays with cell lines relevant for cardiovascular implants and bone prosthesis (endothelial cells and premyoblasts) showed that the drug-loaded coating allows for cell proliferation and viability. The study of CIP and PAR cytotoxicity and release rate indicated that the porous PCL layer does not release concentrations detrimental to the cells. However, complete system assays revealed that corrosion behavior and increase of the pH negatively affects cell viability. H2 evolution during corrosion of Mg alloy substrate generates blisters in PCL layer that accelerate the corrosion locally in crevice microenvironment. A detailed mechanism of the system degradation is disclosed. The accelerated degradation of the developed system may present interest for its further adaptation to new cancer therapy strategies.

Tailored Coatings for Enhanced Performance of Zinc-Magnesium Alloys in Absorbable Implants.

Absorbable metals exhibit potential for next-generation temporary medical implants, dissolving safely in the body during tissue healing and regeneration. Their commercial incorporation could substantially diminish the need for additional surgeries and complications that are tied to permanent devices. Despite extensive research on magnesium (Mg) and iron (Fe), achieving the optimal combination of mechanical properties, biocompatibility, and controlled degradation rate for absorbable implants remains a challenge. Zinc (Zn) and Zn-based alloys emerged as an attractive alternative for absorbable implants, due to favorable combination of in vivo biocompatibility and degradation behavior. Moreover, the development of suitable coatings can enhance their biological characteristics and tailor their degradation process. In this work, four different biodegradable coatings (based on zinc phosphate (ZnP), collagen (Col), and Ag-doped bioactive glass nanoparticles (AgBGNs)) were synthesized by chemical conversion, spin-coating, or a combination of both on Zn-3Mg substrates. This study assessed the impact of the coatings on in vitro degradation behavior, cytocompatibility, and antibacterial activity. The ZnP-coated samples demonstrated controlled weight loss and a decreased corrosion rate over time, maintaining a physiological pH. Extracts from the uncoated, ZnP-coated, and Col-AgBGN-coated samples showed higher cell viability with increasing concentration. Bacterial viability was significantly impaired in all coated samples, particularly in the Col-AgBGN coating. This study showcases the potential of a strategic material-coating combination to effectively tackle multiple challenges encountered in current medical implant technologies by modifying the properties of absorbable metals to tailor patient treatments.