Bioactive Coatings Research Articles

Development and Preclinical Trials of Castomized Porous Titanium Implants with Bioactive Coatings in Model Systems

This paper presents a technology for creating customized porous titanium implants with bioactive coatings, manufactured using additive technologies. The stages of creating an implant include obtaining primary data from the bone defect area using computed tomography; 3D modeling of the defect area and the corresponding implant; production of a customized implant from titanium alloys using selective laser fusion technology; application of bioactive coatings. The as-created customized implant can have several functional structures. Samples of titanium implants with bioactive coatings were subjected to extensive testing. Mathematical modeling and experiments were used to verify the correspondence of the mechanical properties of the developed structures to natural bone tissue. In vitro tests of the studied samples showed the absence of acute toxicity along with high levels of biocompatibility. In vivo tests of the studied samples on Soviet chinchilla rabbits and Anubis baboon monkeys approved by local ethical committees showed their adequate biomechanical and high osteoinductive properties. The successful results of preclinical studies, as well as toxicological and technical tests in certified laboratories, made it possible to create a registration dossier for state registration of customized porous titanium implants with bioactive coatings, manufactured using additive technologies.

Biodegradable Cardiac Occluder with Surface Modification by Gelatin-Peptide Conjugate to Promote Endogenous Tissue Regeneration.

Transcatheter intervention has been the preferred treatment for congenital structural heart diseases by implanting occluders into the heart defect site through minimally invasive access. Biodegradable polymers provide a promising alternative for cardiovascular implants by conferring therapeutic function and eliminating long-term complications, but inducing in situ cardiac tissue regeneration remains a substantial clinical challenge. PGAG (polydioxanone/poly (l-lactic acid)-gelatin-A5G81) occluders are prepared by covalently conjugating biomolecules composed of gelatin and layer adhesive protein-derived peptides (A5G81) to the surface of polydioxanone and poly (l-lactic acid) fibers. The polymer microfiber-biomacromolecule-peptide frame with biophysical and biochemical cues could orchestrate the biomaterial-host cell interactions, by recruiting endogenous endothelial cells, promoting their adhesion and proliferation, and polarizing immune cells into anti-inflammatory phenotypes and augmenting the release of reparative cytokines. In a porcine atrial septal defect (ASD) model, PGAG occluders promote in situ tissue regeneration by accelerating surface endothelialization and regulating immune response, which mitigate inflammation and fibrosis formation, and facilitate the fusion of occluder with surrounding heart tissue. Collectively, this work highlights the modulation of cell-biomaterial interactions for tissue regeneration in cardiac defect models, ensuring endothelialization and extracellular matrix remodeling on polymeric scaffolds. Bioinspired cell-material interface offers a highly efficient and generalized approach for constructing bioactive coatings on medical devices.

Electrophoretic Deposition of ZnO-Containing Bioactive Glass Coatings on AISI 316L Stainless Steel for Biomedical Applications

The main objective of this investigation was to study the implications of incorporating zinc oxide nanoparticles into the matrix of a bioactive glass for the bioactivity and structural properties of the deposited coating. ZnO-containing bioactive glass was coated on an AISI 316L stainless steel substrate using the electrophoretic deposition technique. AISI 316L stainless steel is a biomedical grade steel, which is widely used in different biomedical applications. For the electrophoretic deposition, voltages and times were chosen in the range of 15–40 V and 15–120 min, respectively. The microstructure, phase composition, and surface roughness of coated samples were analyzed in this investigation. Moreover, the corrosion behavior and the MTT (mitochondrial activity) of samples were studied. Results showed a uniform distribution of elements such as silicon and calcium, characteristic of bioactive glass 58S5, in the coating as well as the uniform distribution of Zn inside the ZnO-containing samples. The findings showed that the deposited ZnO-containing bioactive glass is a hydrophilic surface with a relatively rough surface texture. The results of the MTT and antibacterial effects showed that the deposited layers have promising cell viability.

Perspectives on the impact of crystallization in bioactive glasses and glass‐ceramics

AbstractBoth unwanted and induced crystallization can impact bioactivity, physical and mechanical properties of bioactive glasses (BGs). Uncontrolled crystallization has negative consequences, rendering BGs unreliable. However, by manipulating the type, size, shape, and quantity of crystals in BGs, plenty of opportunities arise for controlling, for example, mechanical properties and degradability, leading to unique applications and improved performance. Understanding crystallization is a key step in developing bioactive glasses and glass‐ceramics (BGCs), and both fundamental and experimental research can aid in the design of BGCs for processing and biological function. In this perspective, we discuss the sources of crystallization and how controlled crystallization facilitates the functionalization of bioactive scaffolds, hybrids, coatings, composites, cements, and fibers.

Application of antimicrobial chitosan-Furcellaran-hydrolysate gelatin edible coatings enriched with bioactive peptides in shelf-life extension of pork loin stored at 4 and −20 °C

In this study, the authors investigate the preservative capabilities of edible coatings comprising a blend of chitosan, furcellaran and gelatin hydrolysate enhanced with the bioactive peptides RW4 and LL37. The preservative effects on pork samples stored for 21 days at 4 °C and 6 months at −20 °C were studied, while examining changes in microbiological contamination, pH levels, water activity and sensory attributes. Microbiological analyses reveal the coatings' antimicrobial efficacy against aerobic bacteria, microscopic fungi and yeasts, particularly during the initial storage period, when coated samples exhibit microbial reductions of 0.5–2 log CFU/g compared to the controls. The coatings have no discernible impact on water activity during storage in refrigerated or freezer conditions. Notably, differences in pH development can be observed between the coated and control samples, potentially attributable to the antimicrobial action of the coatings. Sensory analysis allows to highlight the inhibition of deterioration related to sensory attributes through the use of edible coatings. In conclusion, employing bioactive peptide-enriched edible coatings holds promise for extending the shelf-life of perishable foods.

Micro-arc oxidation (MAO) and its potential for improving the performance of titanium implants in biomedical applications.

Titanium (Ti) and its alloys have good biocompatibility, mechanical properties and corrosion resistance, making them attractive for biomedical applications. However, their biological inertness and lack of antimicrobial properties may compromise the success of implants. In this review, the potential of micro-arc oxidation (MAO) technology to create bioactive coatings on Ti implants is discussed. The review covers the following aspects: 1) different factors, such as electrolyte, voltage and current, affect the properties of MAO coatings; 2) MAO coatings affect biocompatibility, including cytocompatibility, hemocompatibility, angiogenic activity, corrosion resistance, osteogenic activity and osseointegration; 3) antibacterial properties can be achieved by adding copper (Cu), silver (Ag), zinc (Zn) and other elements to achieve antimicrobial properties; and 4) MAO can be combined with other physical and chemical techniques to enhance the performance of MAO coatings. It is concluded that MAO coatings offer new opportunities for improving the use of Ti and its alloys in biomedical applications, and some suggestions for future research are provided.

Nano-Zirconia Synthesis Methods and their Pioneering Applications in Dentistry

Nano-zirconia, also known as nanocrystalline zirconia or zirconia nanoparticles, is a versatile material with numerous applications in various fields, including catalysis, sensors, energy storage, and biomedical engineering. This review manuscript explores the synthesis methods of nano-zirconia, focusing on the sol-gel method, precipitation method, hydrothermal method, flame spray pyrolysis, and template-assisted synthesis. Each method is discussed in detail, highlighting its advantages and disadvantages. The selection of a synthesis approach depends on factors such as desired properties, scalability, cost, and equipment availability. Furthermore, the study examines specific dental applications where nano-zirconia materials find utility. In dental implantology, nano-zirconia implants have shown promising results in terms of osseointegration, with comparable or superior performance to titanium implants. Surface modifications, such as bioactive coatings, have been explored to enhance osseointegration and long-term success. Additionally, nano-zirconia ceramics have been utilized in dental prostheses, such as crowns, due to their biocompatibility and exceptional strength. Studies have evaluated the mechanical properties and translucency of different zirconia compositions for dental restorations. Moreover, improvements in the sol-gel process have led to the development of zirconia-silica glass ceramics with enhanced aesthetics and corrosion resistance. Lastly, the impact of professional tooth cleaning on zirconia dental prostheses has been investigated, providing insights into surface properties and bacterial adherence. Overall, nano-zirconia materials offer great potential in various dental applications, and their synthesis methods can be tailored to obtain desired properties for specific uses. Further research and optimization are required to fully explore and exploit the capabilities of nano-zirconia in dental settings.

Titanium-Dioxide-Nanoparticle-Embedded Polyelectrolyte Multilayer as an Osteoconductive and Antimicrobial Surface Coating

Bioactive surface coatings have retained the attention of researchers and physicians due to their versatility and range of applications in orthopedics, particularly in infection prevention. Antibacterial metal nanoparticles (mNPs) are a promising therapeutic, with vast application opportunities on orthopedic implants. The current research aimed to construct a polyelectrolyte multilayer on a highly porous titanium implant using alternating thin film coatings of chitosan and alginate via the layer-by-layer (LbL) self-assembly technique, along with the incorporation of silver nanoparticles (AgNPs) or titanium dioxide nanoparticles (TiO2NPs), for antibacterial and osteoconductive activity. These mNPs were characterized for their physicochemical properties using quartz crystal microgravimetry with a dissipation system, nanoparticle tracking analysis, scanning electron microscopy, and atomic force microscopy. Their cytotoxicity and osteogenic differentiation capabilities were assessed using AlamarBlue and alkaline phosphatase (ALP) activity assays, respectively. The antibiofilm efficacy of the mNPs was tested against Staphylococcus aureus. The LbL polyelectrolyte coating was successfully applied to the porous titanium substrate. A dose-dependent relationship between nanoparticle concentration and ALP as well as antibacterial effects was observed. TiO2NP samples were also less cytotoxic than their AgNP counterparts, although similarly antimicrobial. Together, these data serve as a proof-of-concept for a novel coating approach for orthopedic implants with antimicrobial and osteoconductive properties.

Surface Engineering of Bioactive Coatings for Improved Stent Hemocompatibility: A Comprehensive Review.

Cardiovascular diseases continue to be a major contributor to illness and death on a global scale, and the implementation of stents has given rise to a revolutionary transformation in the field of interventional cardiology. The thrombotic and restenosis complications associated with stent implantation pose ongoing challenges. In recent years, bioactive coatings have emerged as a promising strategy to enhance stent hemocompatibility and reduce thrombogenicity. This review article provides an overview of the surface engineering techniques employed to improve the hemocompatibility of stents and reduce thrombus formation. It explores the mechanisms underlying thrombosis and discusses the factors influencing platelet activation and fibrin formation on stent surfaces. Various bioactive coatings, including anticoagulant agents, antiplatelet agents, and surface modifications, are discussed in detail, highlighting their potential in reducing thrombogenicity. This article also highlights a multitude of surface modification techniques which can be harnessed to enhance stent hemocompatibility including plasma treatment, physical vapor deposition (PVD), chemical vapor deposition (CVD), and electrodeposition. These techniques offer precise control over surface properties such as roughness, charge, and composition. The ultimate goal is to reduce platelet adhesion, tailor wettability, or facilitate the controlled release of bioactive agents. Evaluation methods for assessing hemocompatibility and thrombogenicity are also reviewed, ranging from in vitro assays to animal models. Recent advances in the field, such as nanotechnology-based coatings and bioactive coatings with controlled drug release systems, are highlighted. Surface engineering of bioactive coatings holds great promise for enhancing the long-term outcomes of stent implantation by enhancing hemocompatibility and reducing thrombogenicity. Future research directions and potential clinical applications are discussed, underscoring the need for continued advancements in this field.

Indoor air VOCs biofiltration by bioactive coating packed bed bioreactors

Bioactive coatings are envisaged as a promising biotechnology to tackle the emerging problem of indoor air pollution. This solution could cope with the low concentrations, the wide range of compounds and the hydrophobicity of some indoor air VOCs, which are the most important bottlenecks regarding the implementation of conventional biotechnologies for indoor air treatment. A bioactive coating-based bioreactor was tested in this study for the abatement of different VOCs (n-hexane, toluene and α-pinene) at different empty bed residence times (EBRT) and inlet VOC concentrations. The performance of this reactor was compared with a conventional biofilm-based bioreactor operated with the same microbial inoculum. After an acclimation period, the bioactive coating-based bioreactor achieved abatements of over 50% for hexane, 80% for toluene and 70% for pinene at EBRTs of 112–56 s and inlet concentrations of 9–15 mg m−3. These results were about 25, 10 and 20% lower than the highest removals recorded in the biofilm-based bioreactor. Both bioreactors experienced a decrease in VOC abatement by ∼25% for hexane, 45% for toluene and 40% for pinene, after reducing the EBRT to 28 s. When inlet VOC concentrations were progressively reduced, VOC abatement efficiencies did not improve. This fact suggested that low EBRTs and low inlet VOCs concentration hindered indoor air pollutant abatement as a result of a limited mass transfer and bioavailability. Metagenomic analyses showed that process operation with toluene, hexane and pinene as the only carbon and energy sources favored an enriched bacterial community represented by the genera Devosia, Mesorhizobium, Sphingobacterium and Mycobacterium, regardless of the bioreactor configuration. Bioactive coatings were used in this work as packing material of a conventional bioreactor, achieving satisfactory VOC abatement similar to a conventional bioreactor.

Biphasic Bioceramic Obtained from Byproducts of Sugar Beet Processing for Use in Bioactive Coatings and Bone Fillings.

This study focuses on developing hydroxyapatite synthesized from a CaCO3-rich byproduct of sugar beet processing called Carbocal® using a hydrothermal reactor. The purpose of this biomaterial is to enhance the osteoinductivity of implantable surfaces and serve as a bone filler, providing a sustainable and economically more affordable alternative. This research involved compositional analysis and micro- and macrostructural physicochemical characterization, complemented with bioactivity and live/dead assays. The biphasic nature of the Carbocal®-derived sample was significant within the context of the bioactivity concept previously proposed in the literature. The bioactivity of the biomaterial was demonstrated through a viability test, where the cell growth was nearly equivalent to that of the positive control. For comparison purposes, the same tests were conducted with two additional samples: hydroxyapatite obtained from CaCO3 and commercial hydroxyapatite. The resulting product of this process is biocompatible and possesses properties similar to natural hydroxyapatite. Consequently, this biomaterial shows potential as a scaffold in tissue engineering and as an adhesive filler to promote bone regeneration within the context of the circular bioeconomy in the geographical area proposed.

Chemoselective Coatings of GL13K Antimicrobial Peptides for Dental Implants.

Dental implant-associated infection is a clinical challenge which poses a significant healthcare and socio-economic burden. To overcome this issue, developing antimicrobial surfaces, including antimicrobial peptide coatings, has gained great attention. Different physical and chemical routes have been used to obtain these biofunctional coatings, which in turn might have a direct influence on their bioactivity and functionality. In this study, we present a silane-based, fast, and efficient chemoselective conjugation of antimicrobial peptides (Cys-GL13K) to coat titanium implant surfaces. Comprehensive surface analysis was performed to confirm the surface functionalization of as-prepared and mechanically challenged coatings. The antibacterial potency of the evaluated surfaces was confirmed against both Streptococcus gordonii and Streptococcus mutans, the primary colonizers and pathogens of dental surfaces, as demonstrated by reduced bacteria viability. Additionally, human dental pulp stem cells demonstrated long-term viability when cultured on Cys-GL13K-grafted titanium surfaces. Cell functionality and antimicrobial capability against multi-species need to be studied further; however, our results confirmed that the proposed chemistry for chemoselective peptide anchoring is a valid alternative to traditional site-unspecific anchoring methods and offers opportunities to modify varying biomaterial surfaces to form potent bioactive coatings with multiple functionalities to prevent infection.

Innovative Integration of Arrayan (Luma apiculata) Extracts in Chitosan Coating for Fresh Strawberry Preservation.

Strawberries are a rich source of vitamins and antioxidants, among other nutrients, but they are highly susceptible to mechanical injuries, dehydration, and microbial spoilage, and thus have a limited post-harvest shelf-life. Bioactive edible coatings have been studied to decrease or prevent these damages. In this study, ethanolic extracts of Arrayan (Luma apiculata), a traditional berry from the south of Chile, were used to enrich a chitosan-based edible film and coat fresh strawberries. A long-term storage (10 °C) study was conducted to determine the strawberries' weight loss, microbial stability, fruit firmness impact, and antioxidant activity. Later, a sensory panel was conducted to determine overall consumer acceptance. Our results show that the bioactive coating inhibited the growth of different pathogenic bacteria and spoilage yeast. In the stored strawberries, the weight loss was significantly lower when the bioactive coating was applied, and the samples' firmness did not change significantly over time. Microbial growth in the treated strawberries was also lower than in the control ones. As expected, the antioxidant activity in the coated strawberries was higher because of the Arrayan extract, which has high antioxidant activity. Regarding sensory qualities, the covered strawberries did not show significant differences from the uncoated samples, with an overall acceptance of 7.64 on a 9-point scale. To our knowledge, this is the first time an edible coating enriched with Arrayan extracts has been reported as able to prevent strawberries' decay and spoilage.

SiO2–CaO rod-like particles in chitosan matrix as bioactive coatings for stainless steel implants

Metals have outstanding mechanical properties, being capable of supporting the combined stresses applied to biomaterials (e.g. orthopaedic implants) by the human body. Metals can be biocompatible (such as Ti or stainless steel) but they are bioinert, they generally do not generate a natural bonding with bone tissue, and it is then necessary to produce a kind of anchor or external fixation to improve the implant-bone interface. The surface chemistry and morphology of stainless steel, a material widely used for orthopaedic implants, can affect the interaction of the implant with the surrounding medium and cell attachment and growth, thus affecting the compatibility between the host tissue and the material. The aim of this work is to enhance the bioactivity of stainless steel implants by the application of a combined coating of chitosan and bioactive silica-calcia (SiCa) rod-shaped particles. Stainless steel substrates were coated in two different concentrations of SiCa particles produced by the Stöber method, immersed in a chitosan matrix via electrophoretic deposition. Thick and homogeneous coatings were achieved following the optimization of the deposition parameters, with average thicknesses between 12 and 19 μm. Although the coating exhibited fast rates of dissolution, the formation of carbonated calcium phosphate could be observed after immersion for 10 days in simulated body fluid (SBF), in microscopic images, which was confirmed via spectroscopic analysis. Murine stromal ST-2 cell proliferation was found after 4 and 10 days of seeding, indicating that the coating was not toxic and able to sustain the adhesion and growth of ST-2 cells.

Transforming Spirulina maxima Biomass into Ultrathin Bioactive Coatings Using an Atmospheric Plasma Jet: A New Approach to Healing of Infected Wounds.

The challenge of wound healing, particularly in patients with comorbidities such as diabetes, is intensified by wound infection and the accelerating problem of bacterial resistance to current remedies such as antibiotics and silver. One promising approach harnesses the bioactive and antibacterial compound C-phycocyanin from the microalga Spirulina maxima. However, the current processes of extracting this compound and developing coatings are unsustainable and difficult to achieve. To circumvent these obstacles, a novel, sustainable argon atmospheric plasma jet (Ar-APJ) technology that transforms S. maxima biomass into bioactive coatings is presented. This Ar-APJ can selectively disrupt the cell walls of S. maxima, converting them into bioactive ultrathin coatings, which are found to be durable under aqueous conditions. The findings demonstrate that Ar-APJ-transformed bioactive coatings show better antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa. Moreover, these coatings exhibit compatibility with macrophages, induce an anti-inflammatory response by reducing interleukin 6 production, and promote cell migration in keratinocytes. This study offers an innovative, single-step, sustainable technology for transforming microalgae into bioactive coatings. The approach reported here has immense potential for the generation of bioactive coatings for combating wound infections and may offer a significant advance in wound care research and application.

Correction: Promoting Osseointegration of New Innocuous Ti–18Zr–13Mo Implant Through Constructing Hierarchically Structured Bioactive Coating

Correction: Promoting Osseointegration of New Innocuous Ti–18Zr–13Mo Implant Through Constructing Hierarchically Structured Bioactive Coating

Numerical simulation study on the formation mechanism of hydroxyapatite-silver gradient bioactive ceramic coatings under wide-band laser cladding

Numerical simulation study on the formation mechanism of hydroxyapatite-silver gradient bioactive ceramic coatings under wide-band laser cladding

Electrophoretic deposition of tetracycline loaded bioactive glasses/chitosan as antibacterial and bioactive composite coatings on magnesium alloys

Electrophoretic deposition (EPD) is a coating technique which is widely applied to improve the biocompatibility and anticorrosive performance of medical metal alloys. In this paper EPD was employed to deposit bioactive glasses(BGs)-chitosan(CS) coating loaded with model drug tetracycline(TCH) on AZ31B magnesium alloy to enhance its anti-inflammation, anti-bacteria, anticorrosion and osteogenic induction properties. The electrochemical test showed that the corrosion current density of CS-BGs-1.0 TCH coating was 2 orders of magnitude lower than that of bare AZ31B. In vitro biological activity revealed that after 3 d of immersion in simulated body fluid, the surface of the coating was covered with a layer of hydroxyapatite. In vitro drug release test showed that the drug in CS-BGs-1.0 TCH could be effectively released for 504 h, providing resistance to the formation of bacterial film in a long time. In vitro antibacterial tests indicated that the coating significantly improved the antibacterial activity of magnesium alloy against E.coli. As a result, the prepared coating had better corrosion resistance, antibacterial and biological activity. This coating has good potential in the application of medical devices and bone implant materials.

Bioactive textile coatings for improved viral protection: A study of polypropylene masks coated with copper salt and organic antimicrobial agents

The COVID-19 pandemic emphasized the importance of face masks in reducing virus transmission. However, mask contamination through interpersonal contact or handling demonstrates the need for the development of bioactive textile coatings to reduce mask changes and increase user protection. This study reports the development of polypropylene masks coated with organic antimicrobial agents such as polyethyleneimine (PEI) and lauric acid (Lau), in addition to Cu2+ salts, and their virucidal performance against coronaviruses (MHV-3 strain). Plasma treatment crucially improved the fabric impregnation by the coatings. PEI and Lau coatings significantly reduced viral titer from 99% to 99.99% after 2 h of contact. The PEI coating with copper salt exhibited rapid effect, with a virus inhibition of 99.9% to 99.99% in under a minute, indicating that CuSO4 can significantly enhance the virucidal effect of the coating. Although these coatings demonstrated comparable performance to other virucidal coatings, the presence of copper ions potentializes their effect, rapidly inactivating the virus. These findings highlight the potential of pure organic antimicrobial coatings to enhance mask efficacy and improve protective capabilities. The hybrid coating proves suitable for rapid inactivation of the virus, due to copper fast release and PEI prolonged inhibition effect, enhancing the protection against viral infections.

Bioactive calcium phosphate coatings applied to flexible poly(carbonate urethane) foils

Long-term fixation of orthopaedic implants can be enhanced by tissue ingrowth techniques. As such, the deposition of a bioactive bone-like coating could be considered a promising method to facilitate the integration of implants onto bone tissue. In this study, we identified the optimized osteo-conductive Calcium Phosphate (CaP) coating parameters for deposition on PolyCarbonate-Urethane (PCU) foils. The oxygen plasma surface-activated PCU specimens were suspended in simulated body fluid (SBF) and supersaturated SBFs for 4 h, 8 h, 24 h, or 6 days at a temperature of 20 °C, 37 °C, or 50 °C. This resulted in semi-crystalline CaP coatings on a thin flexible foil via a one-step low-temperature aqueous technique. The deposited CaP coatings demonstrated high stability and remained intact upon bending deformation. According to the in vitro cell assessments, the conducted CaP coatings did not influence cell viability nor cell proliferation compared to the bare PCU substrate. In addition, the deposited CaP coatings enhanced the cell-mediated calcium deposition. All in all, this paper demonstrates a promising method to apply stable bioactive coatings to flexible PCU foils, which can be a promising strategy for the enhanced integration of PCU implants onto bone.