Preliminary Investigation on Degradation Behavior and Cytocompatibility of Ca-P-Sr Coated Pure Zinc

Zinc and its alloys show a good application prospect as a new biodegradable material. However, one of the drawbacks is that Zn and its alloys would induce the release of more Zn ions, which are reported to be cytotoxic to cells. In this study, a Ca-P-Sr bioactive coating was prepared on the surface of pure zinc by the hydrothermal method to address this issue. The morphology, thickness, and composition were characterized, and the effects of the coating on the degradation, cell viability, and ALP staining were investigated. The results demonstrated that the degradation rate of pure zinc was reduced, while the cytocompatibility was significantly improved after pure zinc was treated with Ca-P-Sr coating. It is considered that the Ca-P-Sr bioactive coating prepared by the hydrothermal method has promising application in the clinic.

PROMISING COMPOSITE MATERIALS BASED ON NANOSCALE APATITE WITH GELATIN AS A BINDING AGENT

Порошки наноразмерных гидроксиапатита и фторапатита синтезированы методом осаждения из растворов. В качестве связующего вещества использован пищевой желатин. Такая композиция имеет высокую адгезию на материалах различной природы и пористости. Получены также пористые пленки и гранулы с развитой удельной поверхностью. Рассмотрены их микроструктуры. Изучена возможность использования коллоидной суспензии и водной суспензии кристаллического апатита в сочетании с раствором желатина в качестве биоактивного материала, как для создания покрытий, так и получения гранул. Установлено, что использование порошка апатита совместно с желатином позволяет существенно сократить сроки формирования биоактивного покрытия и значительно повысить его адгезионную прочность. Сопоставлены получаемые гранулы апатита по размерам в зависимости от концентрации желатина в водном растворе. На разработанные биоактивные покрытия и гранулированный материал на основе наноразмерного апатита со связующим агентом поданы заявки на патент. Nanoscale hydroxyapatite and fluorapatite powders were synthesized by precipitation from solutions. Food gelatin is used as a binder. This composition has a high adhesion on materials of different nature and porosity. Porous films and granules with a developed specific surface area were also obtained. Their microstructures are considered. The possibility of using a colloidal suspension and an aqueous suspension of crystalline apatite in combination with a gelatin solution as a bioactive material, both for creating coatings and obtaining granules, has been studied. It is established that the use of apatite powder together with gelatin can significantly reduce the time of formation of a bioactive coating and significantly increase its adhesive strength. The obtained apatite granules are compared in size depending on the concentration of gelatin in an aqueous solution. Patent applications have been filed for the developed bioactive coatings and granular material based on nanoscale apatite with a binding agent.

A Novel Antibacterial Titanium Modification with a Sustained Release of Pac-525

For the benefit of antibacterial Ti on orthopedic and dental implants, a bioactive coating (Pac@PLGA MS/HA coated Ti) was deposited on the surface of pure titanium (Ti), which included two layers: an acid–alkali heat pretreated biomimetic mineralization layer and an electrosprayed Poly (D,L-lactide-co- glycolic acid) (PLGA) microsphere layer as a sustained-release system. Hydroxyapatite (HA) in mineralization layer was primarily prepared on the Ti followed by the antibacterial coating of Pac-525 loaded by PLGA microspheres. After observing the antimicrobial peptides distributed uniformly on the titanium surface, the release assay showed that the release of Pac-525 from Pac@PLGA MS/HA coated Ti provided a large initial burst followed by a slow release at a flat rate. Pac@PLGA MS/HA coated Ti exhibited a strong cytotoxicity to both Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus). In addition, Pac@PLGA MS/HA coated Ti did not affect the growth and adhesion of the osteoblast-like cell line, MC3T3-E1. These data suggested that a bionic mineralized composite coating with long-term antimicrobial activity was successfully prepared.

Surface Treatment and Bioinspired Coating for 3D-Printed Implants

Three-dimensional (3D) printing technology has developed rapidly and demonstrates great potential in biomedical applications. Although 3D printing techniques have good control over the macrostructure of metallic implants, the surface properties have superior control over the tissue response. By focusing on the types of surface treatments, the osseointegration activity of the bone–implant interface is enhanced. Therefore, this review paper aims to discuss the surface functionalities of metallic implants regarding their physical structure, chemical composition, and biological reaction through surface treatment and bioactive coating. The perspective on the current challenges and future directions for development of surface treatment on 3D-printed implants is also presented.

Bioactive coating for tissue-engineered smalldiameter vascular grafts

Objective: to develop a method for modifying composite small-diameter porous tubular biopolymer scaffolds based on bacterial copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and gelatin modified with a double-layered bioactive coating based on heparin (Hp) and platelet lysate (PL) that promote adhesion and proliferation of cell cultures.Materials and methods. Composite porous tubular biopolymer scaffolds with 4 mm internal diameter were made by electrospinning from a 1 : 2 (by volume) mixture of a 10% solution of poly(3-hydroxybutyrateco- 3-hydroxyvalerate) copolymer, commonly known as PHBV, and a 10% solution of gelatin, respectively, in hexafluoro-2-propanol. The structure of the scaffolds was stabilized with glutaraldehyde vapor. The scaffolds were modified with a bioactive Hp + PL-based coating. The surface morphology of the samples was analyzed using scanning electron microscopy. Biological safety of the modified scaffolds in vitro (hemolysis, cytotoxicity) was evaluated based on the GOST ISO 10993 standard. Interaction with cultures of human endothelial cell line (EA. hy926) and human adipose-derived mesenchymal stem cells (hADMSCs) was studied using vital dyes.Results. We developed a method for modifying small-diameter composite porous tubular biopolymer scaffolds obtained by electrospinning from a mixture of PHBV and gelatin modified with double-layered bioactive coating based on covalently immobilized Hp and human PL. The modified scaffold was shown to have no cytotoxicity and hemolytic activity in vitro. It was also demonstrated that the developed coating promotes hADMSC adhesion and proliferation on the external surface and EA.hy926 on the internal surface of the composite porous tubular biopolymer scaffolds in vitro.Conclusion. The developed coating can be used for the formation of in vivo tissueengineered small-diameter vascular grafts.

Vascular Polyurethane Prostheses Modified with a Bioactive Coating—Physicochemical, Mechanical and Biological Properties

This study describes a method for the modification of polyurethane small-diameter (5 mm) vascular prostheses obtained with the phase inversion method. The modification process involves two steps: the introduction of a linker (acrylic acid) and a peptide (REDV and YIGSR). FTIR and XPS analysis confirmed the process of chemical modification. The obtained prostheses had a porosity of approx. 60%, Young’s Modulus in the range of 9–11 MPa, and a water contact angle around 40°. Endothelial (EC) and smooth muscle (SMC) cell co-culture showed that the surfaces modified with peptides increase the adhesion of ECs. At the same time, SMCs adhesion was low both on unmodified and peptide-modified surfaces. Analysis of blood-materials interaction showed high hemocompatibility of obtained materials. The whole blood clotting time assay showed differences in the amount of free hemoglobin present in blood contacted with different materials. It can be concluded that the peptide coating increased the hemocompatibility of the surface by increasing ECs adhesion and, at the same time, decreasing platelet adhesion. When comparing both types of peptide coatings, more promising results were obtained for the surfaces coated with the YISGR than REDV-coated prostheses.

Antimicrobial potential of a bioactive coating based on chitosan incorporated with clove essential oil in hamburger-like meat product

The food industry is looking for strategies to prevent microbial growth in order to ensure food safety and shelf life. However, the use of synthetic preservatives, such as nitrate and nitrite in meat products, entails risks to human health. An alternative is the utilization of essential oils, widely known for their antimicrobial properties. This work aimed the antimicrobial potential of a bioactive coating based on chitosan incorporated with clove essential oil in in hamburger-like meat product. Through the analysis of antimicrobial activity by diffusion in agar and broth, there was an action against Gram-positive and Gram-negative bacteria. Regarding Staphylococcus aureus and Escherichia coli, the minimum inhibitory concentration (MIC) was 3.74 mg/mL and the minimum bactericidal concentration (MBC) was 374.33 mg/mL for both. In the micro atmospheric diffusion test, CEO reduced by up to 70 and 76% of the E. coli and S. aureus bacteria development, respectively. CEO was applied as an active component in chitosan-based coatings in hamburger-like meat, in which it was able to promote the control of microbial proliferation of Total Coliforms, Coliforms at 45 ⁰C and Coagulase-Positive Staphylococcus throughout 7 days of storage under refrigeration. It is concluded that the bioactive coating based on chitosan incorporated with clove essential oil promotes microbiological control in hamburger-like meat product.

The Role of Growth Factors in Bioactive Coatings

With increasing obesity and an ageing population, health complications are also on the rise, such as the need to replace a joint with an artificial one. In both humans and animals, the integration of the implant is crucial, and bioactive coatings play an important role in bone tissue engineering. Since bone tissue engineering is about designing an implant that maximally mimics natural bone and is accepted by the tissue, the search for optimal materials and therapeutic agents and their concentrations is increasing. The incorporation of growth factors (GFs) in a bioactive coating represents a novel approach in bone tissue engineering, in which osteoinduction is enhanced in order to create the optimal conditions for the bone healing process, which crucially affects implant fixation. For the application of GFs in coatings and their implementation in clinical practice, factors such as the choice of one or more GFs, their concentration, the coating material, the method of incorporation, and the implant material must be considered to achieve the desired controlled release. Therefore, the avoidance of revision surgery also depends on the success of the design of the most appropriate bioactive coating. This overview considers the integration of the most common GFs that have been investigated in in vitro and in vivo studies, as well as in human clinical trials, with the aim of applying them in bioactive coatings. An overview of the main therapeutic agents that can stimulate cells to express the GFs necessary for bone tissue development is also provided. The main objective is to present the advantages and disadvantages of the GFs that have shown promise for inclusion in bioactive coatings according to the results of numerous studies.