Development and Characterization of Bioactive Glass Containing Composite Coatings with Ion Releasing Function for Antibiotic-Free Antibacterial Surgical Sutures

Cellulose acetate scaffold coated with a hydroxyapatite/graphene oxide nanocomposite for application in tissue engineering

The objective of this study was to synthesize and characterize porous Cellulose Acetate (CA) scaffolds using the electrospinning technique and functionalize the surface of the scaffolds obtained through the dip-coating method with a Hydroxyapatite (HA) nanocomposite and varying concentrations of graphene oxide (GO) for application in tissue engineering regeneration techniques. The scaffolds were divided into four distinct groups based on their composition: 1) CA scaffolds; 2) CAHAC scaffolds; 3) CAHAGOC 1.0% scaffolds; 4) CAHAGOC 1.5% scaffolds. Scaffold analyses were conducted using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS), and in vitro cell viability assays (WST). For the biological test analysis, Variance (two-way) was used, followed by Tukey's post-test (α = 0.05). The XRD results revealed the predominant presence of CaP phases in the CAHAC, CAHAGOC 1.0%, and CAHAGOC 1.5% groups, emphasizing the presence of HA in the scaffolds. FTIR demonstrated characteristics of cellulose and PO4 bands in the groups containing HA, confirming the presence of CaP in the synthesized materials, as also indicated by XRD. Raman spectroscopy showed the presence of D and G bands, consistent with GO, confirming the successful incorporation of the HAGO nanocomposite into the scaffolds. The micrographs displayed overlapping electrospun fibers, forming the three-dimensional structure in the produced scaffolds. It was possible to observe hydroxyapatite crystals filling some of these pores, creating a suitable structure for cell adhesion, proliferation, and nutrition, as corroborated by the results of in vitro tests. All scaffolds exhibited high cell viability, with significant cell proliferation. Even after 48 h, there was a slight reduction in the number of cells, but a noteworthy increase in cell proliferation was evident in the CAHAGOC 1.5% group after 48 h (p < 0.05). In conclusion, it can be affirmed that the produced scaffolds demonstrated physical and biological characteristics and properties capable of promoting cell adhesion and proliferation. Therefore, they represent significant potential for application in tissue engineering, offering a new perspective regarding techniques and biomaterials applied in regenerative therapies.

Fabrication of a Biocompatible Nanoantimicrobial Suture for Rapid Wound Healing after Surgery

Suture-associated infections on surgical sites are known to be related to the surface characteristics of the sutures. The present study aimed to fabricate a novel functional suture for surgical procedures and characterize its antioxidative, antimicrobial, and in vitro wound healing properties. St John's wort, Hypericum perforatum, extract (eHp), and biogenic silver nanoparticles (AgNPs) have been combined and used for coating the silk sutures. Antioxidant, antimicrobial capacity, and in vitro wound healing potential of the coated sutures have been examined. The morphological and microanalytical examination of the coated sutures was also performed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). According to the antioxidant activity tests, free radical scavenging and β-carotene linoleic acid tests revealed that the antioxidative potential of H. perforatum extract-AgNP combination (eHp-AgNP) at 10 mg/mL concentration was higher than those of positive controls, ascorbic acid and α-tocopherol. Coating the sutures with eHp-AgNP resulted in a remarkable inhibition activity of the sutures against Staphylococcus aureus, which is a pathogenic member of human microbiota. When compared with the control groups, it was investigated that coating the sutures with eHp-AgNP stimulated the cell migration of the fibroblasts to heal the artificial wound. Due to their beneficial effects, the eHp-AgNP-coated silk sutures might be a potential antibacterial and wound healing accelerator for surgical approaches.

Engineering mesoporous bioactive glasses for emerging stimuli-responsive drug delivery and theranostic applications

Mesoporous bioactive glasses (MBGs), which belong to the category of modern porous nanomaterials, have garnered significant attention due to their impressive biological activities, appealing physicochemical properties, and desirable morphological features. They hold immense potential for utilization in diverse fields, including adsorption, separation, catalysis, bioengineering, and medicine. Despite possessing interior porous structures, excellent morphological characteristics, and superior biocompatibility, primitive MBGs face challenges related to weak encapsulation efficiency, drug loading, and mechanical strength when applied in biomedical fields. It is important to note that the advantageous attributes of MBGs can be effectively preserved by incorporating supramolecular assemblies, miscellaneous metal species, and their conjugates into the material surfaces or intrinsic mesoporous networks. The innovative advancements in these modified colloidal inorganic nanocarriers inspire researchers to explore novel applications, such as stimuli-responsive drug delivery, with exceptional in-vivo performances. In view of the above, we outline the fabrication process of calcium-silicon-phosphorus based MBGs, followed by discussions on their significant progress in various engineered strategies involving surface functionalization, nanostructures, and network modification. Furthermore, we emphasize the recent advancements in the textural and physicochemical properties of MBGs, along with their theranostic potentials in multiple cancerous and non-cancerous diseases. Lastly, we recapitulate compelling viewpoints, with specific considerations given from bench to bedside.

Developing a bioactive glass coated dental floss: antibacterial and mechanical evaluations

In the present study, we investigated commercial dental floss coated with chitosan or chitosan + mesoporous bioactive glass nanoparticles (MBGNs) in order to determine the antimicrobial and mechanical properties of the newly fabricated flosses. Whereas these coatings showed notable ability to inhibit growth of both Gram (+) and Gram (-) bacteria after 24 h, the impact was negligible at 3 h. Furthermore, the tensile strength of the floss was improved by the addition of these layers, making it more durable and effective for cleaning between teeth. We therefore propose enhanced investigations of these composites since they demonstrate enormous potential in promoting oral health.

Effect of Aging on Tendon Biology, Biomechanics and Implications for Treatment Approaches

Tendon aging is associated with an increasing prevalence of tendon injuries and/or chronic tendon diseases, such as tendinopathy, which affects approximately 25% of the adult population. Aged tendons are often characterized by a reduction in the number and functionality of tendon stem/progenitor cells (TSPCs), fragmented or disorganized collagen bundles, and an increased deposition of glycosaminoglycans (GAGs), leading to pain, inflammation, and impaired mobility. Although the exact pathology is unknown, overuse and microtrauma from aging are thought to be major causative factors. Due to the hypovascular and hypocellular nature of the tendon microenvironment, healing of aged tendons and related injuries is difficult using current pain/inflammation and surgical management techniques. Therefore, there is a need for novel therapies, specifically cellular therapy such as cell rejuvenation, due to the decreased regenerative capacity during aging. To augment the therapeutic strategies for treating tendon-aging-associated diseases and injuries, a comprehensive understanding of tendon aging pathology is needed. This review summarizes age-related tendon changes, including cell behaviors, extracellular matrix (ECM) composition, biomechanical properties and healing capacity. Additionally, the impact of conventional treatments (diet, exercise, and surgery) is discussed, and recent advanced strategies (cell rejuvenation) are highlighted to address aged tendon healing. This review underscores the molecular and cellular linkages between aged tendon biomechanical properties and the healing response, and provides an overview of current and novel strategies for treating aged tendons. Understanding the underlying rationale for future basic and translational studies of tendon aging is crucial to the development of advanced therapeutics for tendon regeneration.

The potential of microalgal sources as coating materials: A case study for the development of biocompatible surgical sutures

Sutures are considered as surgical materials that form excellent surfaces to integrate the postoperative parts of the body. These materials present suitable platforms for potential bacterial penetrations. Therefore, coating these biomedical materials with biocompatible compounds is seen as a potential approach to improve their properties while avoiding adverse effects. The aim of this study was to evaluate Arthrospira platensis, Haematacoccus pluvialis, Chlorella minutissima, Botyrococcus braunii, and Nostoc muscorum as potential surgical suture coating materials. Their crude extracts were absorbed into two different sutures as poly glycolic (90%)-co-lactic acid (10%) (PGLA) and poly dioxanone (PDO); then, their cytotoxic effects and antibacterial activities were examined. Both N. muscorum-coated sutures (PGLA and PDO) and A. platensis-coated (PGLA and PDO) sutures did not induce any toxic effect on L929 mouse fibroblast cells (>70% cell viability). The highest antibacterial activity against Staphylococcus aureus was achieved with N. muscorum-coated PGLA and A. platensis-coated PGLA at 11.18 ± 0.54 mm and 9.52 ± 1.15 mm, respectively. These sutures were examined by mechanical analysis, and found suitable according to ISO 10993-5. In comparison with the commercial antibacterial agent (chlorohexidine), the results proved that N. muscorum extract can be considered as the most promising suture coating material for the human applications.

Melaleuca armillaris Essential Oil as an Antibacterial Agent: The Use of Mesoporous Bioactive Glass Nanoparticles as Drug Carrier

Bioactive glasses have been proposed for bone tissue engineering due to their excellent biocompatibility and osteo-inductive behaviour. The generation of mesoporous bioactive glass (nano) particles adds a high surface area for the dissolution and release of bioactive ions, and the possibility to load them with different drugs for antibacterial purposes. Essential oils (EO) are an interesting resource for alternative medical therapy, providing antimicrobial compounds that come from organic/natural resources like aromatic plants. Also, a biological polymer, such as chitosan, could be used to control the release of active agents from mesoporous bioactive glass (MBG) loaded particles. This work presents MBG particles with nominal composition (in mol) 60% SiO2, 30% CaO and 10% P2O5, loaded with essential oil of Melaleuca armillaris, which contains 1,8-cineol as the main active component, with an inhibitory in vitro activity against several bacterial species. Also, co-loading with a broad-spectrum antibiotic, namely gentamicin, was investigated. The MBG particles were found to be of around 300nm in diameter and to exhibit highly porous open structure. The release of EO from the particles reached 72% of the initial content after the first 24 h, and 80% at 48 h of immersion in phosphate buffered solution. Also, the MBG particles with EO and EO-gentamicin loading presented in vitro apatite formation after 7 days of immersion in simulated body fluid. The antibacterial tests indicated that the main effect, after 24 h of contact with the bacteria, was reached either for the MBG EO or MBG EO-gentamicin particles against E. coli, while the effect against S. aureus was less marked. The results indicate that MBG particles are highly bioactive with the tested composition and loaded with EO of Melaleuca armillaris. The EO, also combined with gentamicin, acts as an antibacterial agent but with different efficacy depending on the bacteria type.

In Vitro and In Vivo Response of Zinc-Containing Mesoporous Bioactive Glasses in a Sheep Animal Model

Zinc-enriched mesoporous bioactive glasses (MBGs) are bioceramics with potential antibacterial and osteogenic properties. However, few assays have been performed to study these properties in animal models. In this study, MBGs enriched with up to 5% ZnO were synthesized, physicochemically characterized, and evaluated for their osteogenic activity both in vitro and in vivo. The ZnO MBGs showed excellent textural properties despite ZnO incorporation. However, the release of Zn²⁺ ions inhibited the mineralization process when immersed in simulated body fluid. In vitro assays showed significantly higher values of viability and expression of early markers of cell differentiation and angiogenesis in a ZnO-content-dependent manner. The next step was to study the osteogenic potential in a sheep bone defect model. Despite their excellent textural properties and cellular response in vitro, the ZnO MBGs were not able to integrate into the bone tissue, which can be explained in terms of inhibition of the mineralization process caused by Zn²⁺ ions. This work highlights the need to develop nanostructured materials for bone regeneration that can mineralize to interact with bone tissue and induce the processes of implant acceptance, cell colonization by osteogenic cells, and regeneration of lost bone tissue.

Bioactive glass-based fibrous wound dressings

Since the discovery of silicate bioactive glass (BG) by Larry Hench in 1969, different classes of BGs have been researched over decades mainly for bone regeneration. More recently, validating the beneficial influence of BGs with tailored compositions on angiogenesis, immunogenicity and bacterial infection, the applicability of BGs has been extended to soft tissue repair and wound healing. Particularly, fibrous wound dressings comprising BG particle reinforced polymer nanofibers and cotton-candy-like BG fibers have been proven to be successful for wound healing applications. Such fibrous dressing materials imitate the physical structure of skin's extracellular matrix and release biologically active ions e.g. regenerative, pro-angiogenic and antibacterial ions, e.g. borate, copper, zinc, etc., that can provoke cellular activities to regenerate the lost skin tissue and to induce new vessels formation, while keeping an anti-infection environment. In the current review, we discuss different BG fibrous materials meant for wound healing applications and cover the relevant literature in the past decade. The production methods for BG-containing fibers are explained and as fibrous wound dressing materials, their wound healing and bactericidal mechanisms, depending on the ions they release, are discussed. The present gaps in this research area are highlighted and new strategies to address them are suggested.

Engineering surgical stitches to prevent bacterial infection

Surgical site infections (SSIs) account for a massive economic, physiological, and psychological burden on patients and health care providers. Sutures provide a surface to which bacteria can adhere, proliferate, and promote SSIs. Current methods for fighting SSIs involve the use of sutures coated with common antibiotics (triclosan). Unfortunately, these antibiotics have been rendered ineffective due to the increasing rate of antibiotic resistance. A promising new avenue involves the use of metallic nanoparticles (MNPs). MNPs exhibit low cytotoxicity and a strong propensity for killing bacteria while evading the typical antibiotic resistance mechanisms. In this work, we developed a novel MNPs dip-coating method for PDS-II sutures and explored the capabilities of a variety of MNPs in killing bacteria while retaining the cytocompatibility. Our findings indicated that our technique provided a homogeneous coating for PDS-II sutures, maintaining the strength, structural integrity, and degradability. The MNP coatings possess strong in vitro antibacterial properties against P aeruginosa and S. aureus—varying the %of dead bacteria from ~ 40% (for MgO NPs) to ~ 90% (for Fe₂O₃) compared to ~ 15% for uncoated PDS-II suture, after 7 days. All sutures demonstrated minimal cytotoxicity (cell viability > 70%) reinforcing the movement towards the use MNPs as a viable antibacterial technology.

Mesoporous Silica Nanoparticles and Mesoporous Bioactive Glasses for Wound Management: From Skin Regeneration to Cancer Therapy

Exploring new therapies for managing skin wounds is under progress and, in this regard, mesoporous silica nanoparticles (MSNs) and mesoporous bioactive glasses (MBGs) offer great opportunities in treating acute, chronic, and malignant wounds. In general, therapeutic effectiveness of both MSNs and MBGs in different formulations (fine powder, fibers, composites etc.) has been proved over all the four stages of normal wound healing including hemostasis, inflammation, proliferation, and remodeling. The main merits of these porous substances can be summarized as their excellent biocompatibility and the ability of loading and delivering a wide range of both hydrophobic and hydrophilic bioactive molecules and chemicals. In addition, doping with inorganic elements (e.g., Cu, Ga, and Ta) into MSNs and MBGs structure is a feasible and practical approach to prepare customized materials for improved skin regeneration. Nowadays, MSNs and MBGs could be utilized in the concept of targeted therapy of skin malignancies (e.g., melanoma) by grafting of specific ligands. Since potential effects of various parameters including the chemical composition, particle size/morphology, textural properties, and surface chemistry should be comprehensively determined via cellular in vitro and in vivo assays, it seems still too early to draw a conclusion on ultimate efficacy of MSNs and MBGs in skin regeneration. In this regard, there are some concerns over the final fate of MSNs and MBGs in the wound site plus optimal dosages for achieving the best outcomes that deserve careful investigation in the future.

Anodic Electrodeposition of Chitosan-AgNP Composites Using In Situ Coordination with Copper Ions

Chitosan is an attractive material for biomedical applications. A novel approach for the anodic electrodeposition of chitosan–AgNP composites using in situ coordination with copper ions is proposed in this work. The surface and cross-section morphology of the obtained coating with varying concentrations of AgNPs were evaluated by SEM, and surface functional groups were analyzed with FT-IR spectroscopy. The mechanism of the formation of the coating based on the chelation of Cu(II) ions with chitosan was discussed. The antibacterial activity of the coatings towards Staphylococcus epidermidis ATCC 35984/RP62A bacteria was analyzed using the live–dead approach. The presented results indicate that the obtained chitosan–AgNP-based films possess some limited anti-biofilm-forming properties and exhibit moderate antibacterial efficiency at high AgNP loads.

Biosensitive and antibacterial coatings on metallic material for medical applications

Metallic materials are commonly used for load-bearing implants and as internal fixation devices. It is customary to use austenitic stainless steel, especially surgical grade type 316L SS as temporary and Ti alloys as permanent implants. However, long-term, poor bonding with bone, corrosion, and release of metal ions, such as chromium and nickel occur. These ions are powerful allergens and carcinogens and their uncontrolled leaching may be avoided by surface coatings. Therefore, bioactive glasses (BGs) became a vital biomedical material, which can form a biologically active phase of hydroxycarbonate apatite on their surface when in contact with physiological fluids. To reduce the high coefficient of friction and the brittle nature of BGs, polymers are normally incorporated to avoid the high-temperature sintering/densification of ceramic-only coatings. For medical application, electrophoretic deposition (EPD) is now used for polymer (organic) and ceramic (inorganic) components at room temperature due to its simplicity, control of coating thickness and uniformity, low cost of equipment, ability to coat substrates of intricate shape and to supply thick films in composite form, high purity of deposits as well as no phase transformation during coating. Although extensive research has been conducted on polymer/inorganic composite coatings, only some studies have reported multifunctional properties, such as biological antibacterial activity, enhanced cell adhesion, controlled drug release ability, and mechanical properties. This review will focus on biodegradable coatings, including zien, chitosan, gelatin, cellulose loaded with antibacterial drugs/metallic ions/natural herbs on biostable substrates (PEEK/PMMA/PCL/PLLA layers), which have the potential of multifunctional coating for metallic implants.

(1S,2S)-Cyclohexane-1,2-diamine-based Organosilane Fibres as a Powerful Tool Against Pathogenic Bacteria

An urgent need to find an effective solution to bacterial resistance is pushing worldwide research for highly effective means against this threat. Newly prepared hybrid organosilane fibres consisting of a (1S,2S)-cyclohexane-1,2-diamine derivative, interconnected in the fibre network via covalent bonds, were fully characterised via different techniques, including FTIR, TGA-FTIR, SEM-EDS, and solid-state NMR. Fibrous samples were successfully tested against two types of pathogenic bacterial strains, namely Staphylococcus aureus, and Pseudomonas aeruginosa. The obtained results, showing >99.9% inhibition against Staphylococcus aureus and Pseudomonas aeruginosa in direct contact compared to the control, may help particularly in case of infections, where there is an urgent need to treat the infection in direct contact. From this point of view, the above-mentioned fibrous material may find application in wound healing. Moreover, this new material has a positive impact on fibroblasts viability.

Insights into Theranostic Properties of Titanium Dioxide for Nanomedicine

Titanium dioxide (TiO2) nanostructures exhibit a broad range of theranostic properties that make them attractive for biomedical applications. TiO2 nanostructures promise to improve current theranostic strategies by leveraging the enhanced quantum confinement, thermal conversion, specific surface area, and surface activity. This review highlights certain important aspects of fabrication strategies, which are employed to generate multifunctional TiO2 nanostructures, while outlining post-fabrication techniques with an emphasis on their suitability for nanomedicine. The biodistribution, toxicity, biocompatibility, cellular adhesion, and endocytosis of these nanostructures, when exposed to biological microenvironments, are examined in regard to their geometry, size, and surface chemistry. The final section focuses on recent biomedical applications of TiO2 nanostructures, specifically evaluating therapeutic delivery, photodynamic and sonodynamic therapy, bioimaging, biosensing, tissue regeneration, as well as chronic wound healing.