Surface Functionalization of an Aluminum Alloy to Generate an Antibiofilm Coating Based on Poly(Methyl Methacrylate) and Silver Nanoparticles

Enhancing orthopedic outcomes: A comparative analysis of gentamicin sulphate and nanosilver in bone cement

Background

Orthopedic surgeries frequently utilize bone cement, which can increase the risk of postoperative infections. Addressing this challenge, this study aims to enhance the mechanical, physical, and handling properties of bone cement by integrating gentamicin sulfate (GS) and nanosilver (nAg). The objective is to evaluate and compare the effects of these additives on properties such as compressive strength, flexural strength, doughing time, working time, setting time, and exothermic temperature. By doing so, the study seeks to identify a safer and more effective alternative to traditional antibiotics in bone cement formulations, thereby improving clinical outcomes in orthopedic procedures.

Methods

This research involved a comparative analysis of modified cements against standard cements, focusing on compressive strength, flexural strength, doughing time, working time, setting time, and exothermic temperature. Various bone cement samples with GS and nAg additives were prepared and tested in accordance with international standards (ISO 5833:2002 and ASTM F451). Statistical analysis, including one-way and two-way ANOVA tests, was used to assess the significance of the results.

Results

nAg-loaded cements exhibit mechanical and physical properties on par with or supe-rior to those of GS-loaded and standard cements. Notably, nAg incorporation leads to significantly lower exothermic temperatures, reducing the risk of thermal bone tissue damage. This finding highlights that nAg-loaded cement is a safer alternative. Alongside unaltered or enhanced strength, nAgs demonstrate promise for orthopedic applications, particularly in primary arthroplasty. Additionally, nAgs reduce doughing time, enhancing the practicality of these methods in surgical settings.

Conclusions

In conclusion, this study underscores the potential advantages of incorporating GSs and nAgs into bone cement. nAg-loaded cement offers improved properties and reduced infection risk, making it a valuable choice for orthopedic procedures. It enhances both mechanical performance and safety, addressing crucial concerns in orthopedic surgery.

Assessment of Polydopamine to Reduce Streptococcus mutans Adhesion to a Dental Polymer

Bacterial adhesion to the surface of materials is the first step in biofilm formation, which will lead to conditions that may compromise the health status of patients. Recently, polydopamine (PDA) has been proposed as an antibacterial material. Therefore, the objective of the current work was to assess and compare the adhesion of Streptococcus mutans to the surface of poly(methyl methacrylate) (PMMA) discs that were modified using PDA following a biomimetic approach versus smooth PDA-coated PMMA surfaces. In addition, an assessment of the growth inhibition by PDA was performed. PMMA discs were manufactured and polished; soft lithography, using the topography from the Crocosmia aurea leaf, was used to modify their surface. PDA was used to smooth-coat PMMA discs by dip-coating. The growth inhibition was measured using an inhibition halo. The surfaces were characterized by means of atomic force microscopy (AFM), the contact angle (CA), and Fourier-transform infrared spectroscopy (FTIR). Polydopamine exhibited a significant antibacterial effect when used directly on the S. mutans planktonic cells, but such an effect was not as strong when modifying the PMMA surfaces. These results open the possibility of using polydopamine to reduce the adhesion and growth of S. mutans, which might have important consequences in the dental field.

Scaffolds in the microbial resistant era: Fabrication, materials, properties and tissue engineering applications

Due to microbial infections dramatically affect cell survival and increase the risk of implant failure, scaffolds produced with antimicrobial materials are now much more likely to be successful. Multidrug-resistant infections without suitable prevention strategies are increasing at an alarming rate. The ability of cells to organize, develop, differentiate, produce a functioning extracellular matrix (ECM) and create new functional tissue can all be controlled by careful control of the extracellular microenvironment. This review covers the present state of advanced strategies to develop scaffolds with antimicrobial properties for bone, oral tissue, skin, muscle, nerve, trachea, cardiac and other tissue engineering applications. The review focuses on the development of antimicrobial scaffolds against bacteria and fungi using a wide range of materials, including polymers, biopolymers, glass, ceramics and antimicrobials agents such as antibiotics, antiseptics, antimicrobial polymers, peptides, metals, carbon nanomaterials, combinatorial strategies, and includes discussions on the antimicrobial mechanisms involved in these antimicrobial approaches. The toxicological aspects of these advanced scaffolds are also analyzed to ensure future technological transfer to clinics. The main antimicrobial methods of characterizing scaffolds’ antimicrobial and antibiofilm properties are described. The production methods of these porous supports, such as electrospinning, phase separation, gas foaming, the porogen method, polymerization in solution, fiber mesh coating, self-assembly, membrane lamination, freeze drying, 3D printing and bioprinting, among others, are also included in this article. These important advances in antimicrobial materials-based scaffolds for regenerative medicine offer many new promising avenues to the material design and tissue-engineering communities.

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Antibacterial, antifungal and antibiofilm scaffolds.

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Antimicrobial scaffold fabrication techniques.

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Antimicrobial biomaterials for tissue engineering applications.

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Antimicrobial characterization methods of scaffolds.

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Bone, oral tissue, skin, muscle, nerve, trachea, cardiac, among other applications.

Atomic and Molecular Layer Deposition of Chiral Thin Films Showing up to 99% Spin Selective Transport

Spin electronics is delivering a much desired combination of properties such as high speed, low power, and high device densities for the next generation of memory devices. Utilizing chiral-induced spin selectivity (CISS) effect is a promising path toward efficient and simple spintronic devices. To be compatible with state-of-the-art integrated circuits manufacturing methodologies, vapor phase methodologies for deposition of spin filtering layers are needed. Here, we present vapor phase deposition of hybrid organic-inorganic thin films with embedded chirality. The deposition scheme relies on a combination of atomic and molecular layer deposition (A/MLD) utilizing enantiomeric pure alaninol molecular precursors combined with trimethyl aluminum (TMA) and water. The A/MLD deposition method deliver highly conformal thin films allowing the fabrication of several types of nanometric scale spintronic devices. The devices showed high spin polarization (close to 100%) for 5 nm thick spin filter layer deposited by A/MLD. The procedure is compatible with common device processing methodologies.

In Vitro Study of the Interaction of Innate Immune Cells with Liquid Silicone Rubber Coated with Zwitterionic Methyl Methacrylate and Thermoplastic Polyurethanes

The biocompatibility of medical devices, such as implants and prostheses, is strongly determined by the host's immune response to the implanted material. Monocytes and macrophages are main actors of the so-called foreign body reaction. The innate immune system macrophages (M) can be broadly classified into the pro-inflammatory M1-type and the anti-inflammatory, pro-healing M2-type. While a transient inflammatory initial state can be helpful during an infection, persistent inflammation interferes with proper healing and subsequent regeneration. The functional orientation of the immune response, mirrored by monocyte polarization, during interaction with different biomaterials has not yet been sufficiently explored. In implant manufacturing, thermoplastic polyurethane (TPU) represents the state-of-the-art material. The constantly growing areas of application and the associated necessary adaptations make the optimization of these materials indispensable. In the present study, modified liquid silicone rubber (LSR) were compared with two of the most commonly used TPUs, in terms of monocyte adhesion and M1/M2 polarization in vitro. Human monocytes isolated from venous blood were evaluated for their ability to adhere to various biomaterials, their gene expression profile, and their cytokine release. Based on the results, the different polymers exhibit different potential to bias monocytes with respect to early pro-inflammatory cytokine production and gene transcription. Furthermore, none of our test materials showed a clear trend towards M1 or M2 polarization. However, we were able to evaluate the inflammatory potential of the materials, with the classic TPUs appearing to be the most unreactive compared to the silicone-based materials.

Fluorine-Free Superhydrophobic Coating with Antibiofilm Properties Based on Pickering Emulsion Templating

This study presents antibiofilm coating formulations based on Pickering emulsion templating. The coating contains no bioactive material because its antibiofilm properties stem from passive mechanisms that derive solely from the superhydrophobic nature of the coating. Moreover, unlike most of the superhydrophobic formulations, our system is fluorine-free, thus making the method eminently suitable for food and medical applications. The coating formulation is based on water in toluene or xylene emulsions that are stabilized using commercial hydrophobic silica, with polydimethylsiloxane (PDMS) dissolved in toluene or xylene. The structure of the emulsions and their stability was characterized by confocal microscopy and cryogenic-scanning electron microscopy (cryo-SEM). The most stable emulsions are applied on polypropylene (PP) surfaces and dried in an oven to form PDMS/silica coatings in a process called emulsion templating. The structure of the resulting coatings was investigated by atomic force microscopy (AFM) and SEM. The surface of the coatings shows a honeycomb-like structure that exhibits a combination of micron-scale and nanoscale roughness, which endows it with its superhydrophobic properties. After tuning, the superhydrophobic properties of the coatings demonstrated highly efficient passive antibiofilm activity. In vitro antibiofilm trials with E. coli indicate that the coatings reduced the biofilm accumulation by 83% in the xylene-water-based surfaces and by 59% in the case of toluene-water-based surfaces.

The Use of Zwitterionic Methylmethacrylat Coated Silicone Inhibits Bacterial Adhesion and Biofilm Formation of Staphylococcus aureus

In recent decades, biofilm-associated infections have become a major problem in many medical fields, leading to a high burden on patients and enormous costs for the healthcare system. Microbial infestations are caused by opportunistic pathogens which often enter the incision already during implantation. In the subsequently formed biofilm bacteria are protected from the hosts immune system and antibiotic action. Therefore, the development of modified, anti-microbial implant materials displays an indispensable task. Thermoplastic polyurethane (TPU) represents the state-of-the-art material in implant manufacturing. Due to the constantly growing areas of application and the associated necessary adjustments, the optimization of these materials is essential. In the present study, modified liquid silicone rubber (LSR) surfaces were compared with two of the most commonly used TPUs in terms of bacterial colonization and biofilm formation. The tests were conducted with the clinically relevant bacterial strains Staphylococcus aureus and Staphylococcus epidermidis. Crystal violet staining and scanning electron microscopy showed reduced adhesion of bacteria and thus biofilm formation on these new materials, suggesting that the investigated materials are promising candidates for implant manufacturing.

Functional Antimicrobial Surface Coatings Deposited onto Nanostructured 316L Food-Grade Stainless Steel

In our study, we demonstrated the performance of antimicrobial coatings on properly functionalized and nanostructured 316L food-grade stainless steel pipelines. For the fabrication of these functional coatings, we employed facile and low-cost electrochemical techniques and surface modification processes. The development of a nanoporous structure on the 316L stainless steel surface was performed by following an electropolishing process in an electrolytic bath, at a constant anodic voltage of 40 V for 10 min, while the temperature was maintained between 0 and 10 °C. Subsequently, we incorporated on this nanostructure additional coatings with antimicrobial and bactericide properties, such as Ag nanoparticles, Ag films, or TiO₂ thin layers. These functional coatings were grown on the nanostructured substrate by following electroless process, electrochemical deposition, and atomic layer deposition (ALD) techniques. Then, we analyzed the antimicrobial efficiency of these functionalized materials against different biofilms types (Candida parapsilosis, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis). The results of the present study demonstrate that the nanostructuring and surface functionalization processes constitute a promising route to fabricate novel functional materials exhibiting highly efficient antimicrobial features. In fact, we have shown that our use of an appropriated association of TiO₂ layer and Ag nanoparticle coatings over the nanostructured 316L stainless steel exhibited an excellent antimicrobial behavior for all biofilms examined.

Antibacterial Activity and Cytocompatibility of Bone Cement Enriched with Antibiotic, Nanosilver, and Nanocopper for Bone Regeneration

Bacterial infections due to bone replacement surgeries require modifications of bone cement with antibacterial components. This study aimed to investigate whether the incorporation of gentamicin or nanometals into bone cement may reduce and to what extent bacterial growth without the loss of overall cytocompatibility and adverse effects in vitro. The bone cement Cemex was used as the base material, modified either with gentamicin sulfate or nanometals: Silver or copper. The inhibition of bacterial adhesion and growth was examined against five different bacterial strains along with integrity of erythrocytes, viability of blood platelets, and dental pulp stem cells. Bone cement modified with nanoAg or nanoCu revealed greater bactericidal effects and prevented the biofilm formation better compared to antibiotic-loaded bone cement. The cement containing nanoAg displayed good cytocompatibility without noticeable hemolysis of erythrocytes or blood platelet disfunction and good viability of dental pulp stem cells (DPSC). On the contrary, the nanoCu cement enhanced hemolysis of erythrocytes, reduced the platelets aggregation, and decreased DPSC viability. Based on these studies, we suggest the modification of bone cement with nanoAg may be a good strategy to provide improved implant fixative for bone regeneration purposes.