Antimicrobial and anti-biofilm properties of polypropylene meshes coated with metal-containing DLC thin films

Diamond-like carbon coating to inner surface of polyurethane tube reduces Staphylococcus aureus bacterial adhesion and biofilm formation

Staphylococcus aureus is one of the main causative bacteria for polyurethane catheter and artificial graft infection. Recently, we developed a unique technique for coating diamond-like carbon (DLC) inside the luminal resin structure of polyurethane tubes. This study aimed to elucidate the infection-preventing effects of diamond-like carbon (DLC) coating on a polyurethane surface against S. aureus. We applied DLC to polyurethane tubes and rolled polyurethane sheets with our newly developed DLC coating technique for resin tubes. The DLC-coated and uncoated polyurethane surfaces were tested in smoothness, hydrophilicity, zeta-potential, and anti-bacterial properties against S. aureus (biofilm formation and bacterial attachment) by contact with bacterial fluids under static and flow conditions. The DLC-coated polyurethane surface was significantly smoother, more hydrophilic, and had a more negative zeta-potential than did the uncoated polyurethane surface. Upon exposure to bacterial fluid under both static and flow conditions, DLC-coated polyurethane exhibited significantly less biofilm formation than uncoated polyurethane, based on absorbance measurements. In addition, the adherence of S. aureus was significantly lower for DLC-coated polyurethane than for uncoated polyurethane under both conditions, based on scanning electron microscopy. These results show that applying DLC coating to the luminal resin of polyurethane tubes may impart antimicrobial effects against S. aureus to implantable medical polyurethane devices, such as vascular grafts and central venous catheters.

Sputtering of micro-carbon-silver film (μC-Ag) for endotracheal tubes to mitigate respiratory infections

Polyurethane (PU) substrates are biocompatible materials widely used to manufacture endotracheal tubes. However, in common with other biomedical materials, they are liable to the formation of microbial films. The occurrence of pneumonia in intubated patients treated at intensive care units often takes the form of ventilator-associated pneumonia (VAP). The issue relates to the translocation of pathogenic microorganisms that colonize the oropharyngeal mucosa, dental plaque, stomach, and sinuses. New protective materials can provide a more effective therapeutic approach to mitigating bacterial films. This work concerns microcrystalline carbon film containing dispersed silver nanoparticles (μC-Ag) deposited on PU substrates using a physical vapor deposition sputtering process. For the first time, carbon paper was used to produce a carbon target with holes exposing a silver disk positioned under the carbon paper, forming a single target for use in the sputtering system. The silver nanoparticles were well distributed in the carbon film. The adherence characteristics of the μC-Ag film were evaluated using a tape test technique, and electron dispersive x-ray mapping was performed to analyze the residual particles after the tape test. The microbicidal effect of the thin film was also investigated using speciesS. aureus, a pathogenic microorganism responsible for most infections of the lower respiratory tract involving VAP and ventilator-associated tracheobronchitis (VAT). The results demonstrated that μC-Ag films on PU substrates are promising materials for mitigating pathogenic microorganisms on endotracheal tubes.

Current Advances and Applications of Tantalum Element in Infected Bone Defects

Infected bone defects (IBDs) cause significant economic and psychological burdens, posing a huge challenge to clinical orthopedic surgeons. Traditional approaches for managing IBDs possess inevitable shortcomings; therefore, it is necessary to develop new functionalized scaffolds. Tantalum (Ta) has been widely used in load-bearing orthopedic implants due to its good biocompatibility and corrosion resistance. However, undecorated Ta could only structurally repair common bone defects, which failed to meet the clinical needs of bacteriostasis for IBDs. Researchers have made great efforts to functionalize Ta scaffolds to enhance their antibacterial activity through various methods, including surface coating, alloying, and micro- and nanostructure modifications. Additionally, several studies have successfully utilized Ta to modify orthopedic scaffolds for enhanced antibacterial function. These studies remarkably extended the application range of Ta. Therefore, this review systematically outlines the advances in the fundamental and clinical application of Ta in the treatment of IBDs, focusing on the antibacterial properties of Ta, its functionalization for bacteriostasis, and its applications in the modification of orthopedic scaffolds. This study provides researchers with an overview of the application of Ta in the treatment of IBDs.

A review: strategies to reduce infection in tantalum and its derivative applied to implants

Implant-associated infection is the main reasons for implant failure. Titanium and titanium alloy are currently the most widely used implant materials. However, they have limited antibacterial performance. Therefore, enhancing the antibacterial ability of implants by surface modification technology has become a trend of research. Tantalum is a potential implant coating material with good biological properties. With the development of surface modification technology, tantalum coating becomes more functional through improvement. In addition to improving osseointegration, its antibacterial performance has also become the focus of attention. In this review, we provide an overview of the latest strategies to improve tantalum antibacterial properties. We demonstrate the potential of the clinical application of tantalum in reducing implant infections by stressing its advantageous properties.

Diamond-like Carbon Coatings in the Biomedical Field: Properties, Applications and Future Development

Repairment and replacement of organs and tissues are part of the history of struggle against human diseases, in addition to the research and development (R&D) of drugs. Acquisition and processing of specific substances and physiological signals are very important to understand the effects of pathology and treatment. These depend on the available biomedical materials. The family of diamond-like carbon coatings (DLCs) has been extensively applied in many industrial fields. DLCs have also been demonstrated to be biocompatible, both in vivo and in vitro. In many cases, the performance of biomedical devices can be effectively enhanced by coating them with DLCs, such as vascular stents, prosthetic heart valves and surgical instruments. However, the feasibility of the application of DLC in biomedicine remains under discussion. This review introduces the current state of research and application of DLCs in biomedical devices, their potential application in biosensors and urgent problems to be solved. It will be useful to build a bridge between DLC R&D workers and biomedical workers in order to develop high-performance DLC films/coatings, promote their practical use and develop their potential applications in the biomedical field.

Antimicrobial Meshes for Hernia Repair: Current Progress and Perspectives

Recent advances in the development of biomaterials have given rise to new options for surgery. New-generation medical devices can control chemical breakdown and resorption, prevent post-operative adhesion, and stimulate tissue regeneration. For the fabrication of medical devices, numerous biomaterials can be employed, including non-degradable biomaterials (silicone, polypropylene, expanded polytetrafluoroethylene) or biodegradable polymers, including implants and three-dimensional scaffolds for tissue engineering, which require particular physicochemical and biological properties. Based on the combination of new generation technologies and cell-based therapies, the biocompatible and bioactive properties of some of these medical products can lead to progress in the repair of injured or harmed tissue and in tissue regeneration. An important aspect in the use of these prosthetic devices is the associated infection risk, due to the medical complications and socio-economic impact. This paper provides the latest achievements in the field of antimicrobial surgical meshes for hernia repair and discusses the perspectives in the development of these innovative biomaterials.

Evaluation of biofilm formation on different clear orthodontic retainer materials

Aim:

To assess the chemical composition and oral biofilm formation on different types of commercially available clear orthodontic retainer materials (CORM).

Materials and Methods:

Four types of CORM commercially available were used (Clear advantage series I (CAS1), Clear advantage series II (CAS2), Endure (ES), and CENTRI FORM-clear rigid material (CFCRM)). Circular samples (12 mm diameter) of each CORM were prepared for (n = 40). Unstimulated saliva from twenty volunteers was collected. Fourier Transformation Infrared Spectroscopy (FTIR) was used for the evaluation of the chemical composition of CORM. For the quantitative assessment of oral biofilm formation, samples of each CORM were incubated for twenty-four hours, and crystal violet assay (CVA) was utilized. The degree of absorbance was measured using a spectrophotometer at 570 nm. For qualitative evaluation of oral formation, the samples of each CORM were incubated for 24 hours, and viable biofilm cells stained by acridine orange were examined under a fluorescent microscope.

Results:

FTIR findings showed that CAS2 was made of polypropylene and ES is made of polyvinyl chloride, while others were made of co-polyester. CVA results confirmed that CAS2 showed the lowest biofilm formation, which differs significantly compared to CAS1, CFCRM, and ES. No significant difference in biofilm formation was detected between CAS1, CFCRM, and ES. Viable biofilm cells staining by acridine orange showed that CAS2 demonstrated smaller microcolonies of viable biofilm cells compared with CAS1, CFCRM, and ES, which confirmed the result obtained by CVA.

Conclusions:

CAS2 showed anti-microbial activities with a decrease the in vitro biofilm formation, which may be related to its chemical composition.

Active bayerite underpinned Ag2O/Ag: An efficient antibacterial nanohybrid combating microbial contamination

Active surfaces with bactericidal properties are of paramount importance in health care sector as a judicious approach to confront prevalent challenges presented by disastrous pathogenic infections and antibiotic-resistant microbes. Herein, we present Bayerite underpinned Ag2O/Ag (ALD), a nanohybrid with excellent antibacterial and antibiofilm functionalities against tested standard strains and clinical isolates. The multicomponent system coexists and complement each other with respect to phase and functionalities, demonstrated by XRD, XPS and TEM analyses. In situ reduction of Ag+ ions to Ag0 over Bayerite as a stable bound phase is favoured by pH of the reaction, yielding 60-80% bound Ag protruding outwards facilitating active surface for interaction with microbes. ALD has a minimum inhibitory concentration (MIC) of 0.068 mg/mL against clinical isolates: Pseudomonas aeruginosa RRLP1, RRLP2, Acinetobactor baumannii C78 and C80. Disc diffusion assay demonstrated excellent antibacterial activity against standard strains (positive control: standard antibiotic disc, Amikacin). ALD incorporated PMMA films (5 and 10 wt%(PALD-5 and PALD-10) exhibited significant contact killing (99.9%) of clinical isolates in drop-test besides strong antibacterial activity (disc diffusion assay) comparable to that of ALD. ALD exemplified a dose (0.034 mg/mL and 0.017 mg/mL) dependent biofilm inhibition (p < 0.001) and significant eradication of pre-formed biofilms (p < 0.001) by clinical isolates. PALD 5 and PALD 10 significantly declined the number of viable biofilm associated bacteria (99.9%) compared to control. Both ALD and PALD samples are proposed as green antibacterial materials with antibiofilm properties. Results also present ample opportunity to explore PALD as antibacterial and/or antibiofilm coating formulations.

Fabricating Ultra-Smooth Diamond-Like Carbon Film and Investigating its Antifungal and Antibiofilm Activity

Diamond like carbon (DLC) a carbon-based nanomaterial has been nominated as a potential solution to prevent the biofilm formation on indwelling medical devices such as dentures and heart valves.Candidaalbicansis an opportunistic fungal pathogen where biofilms are a part of its pathogenicity which primarily utilized indwelling medical devices as platform to build up the biofilm. In this work, DLC deposited on silicon substrate was prepared to accomplish the optimal characteristics for bio-coating material (roughness, purity, uniformity) and then evaluated for their ability to prevent or reduce the biofilm formation of pathogenicC.albicans(SC5314) under conditions mimicking human body. Optimized DLC was synthesized via chemical vapor deposition, and then the film was characterized by Raman spectroscopy, scan electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), and atomic force microscopy (AFM). The potential biofilms on DLC, silicon substrate and positive control (polyvinyl chloride-PVC) were quantified via colorimetric cell viability assay (XTT); as intact and vortexed biofilms. The characteristics of formed biofilms were carried out using confocal scanning laser microscopy (CSLM) and scan electron microscope (SEM). The result showed that DLC was successfully deposited on the silicon substrate with a root mean square (RMS) roughness of 0.183± 0.09 nm. The biofilm efficaciously grown on all samples (DLC and positive control) with thickness of 46.8 ± 6.97 μm and 42.18 ± 4.65 μm, respectively. No topological and morphological changes have been observed by SEM on biofilm-DLC compared to PVC-biofilm. Moreover, all results indicated that the hydrophobicity and roughness of DLC appeared to support the attachment and the growth ofC.albicans.In conclusion , there is no privilege of utilizing DLC over PVC in term of reduction or inhibition ofC.albicansbiofilm formation at physiological conditions. Furthermore, this study may serve as an experimental model to evaluate the potential effect of nanomaterials coating on biofilm formation at conditions mimicking human’s body.

Harnessing Metal Homeostasis Offers Novel and Promising Targets Against Candida albicans

Fungal infections, particularly of Candida species, which are the commensal organisms of human, are one of the major debilitating diseases in immunocompromised patients. The limited number of antifungal drugs available to treat Candida infections, with the concomitant increasing incidence of multidrug-resistant (MDR) strains, further worsens the therapeutic options. Thus, there is an urgent need for the better understanding of MDR mechanisms, and their reversal, by employing new strategies to increase the efficacy and safety profiles of currently used therapies against the most prevalent human fungal pathogen, Candida albicans. Micronutrient availability during C. albicans infection is regarded as a critical factor that influences the progression and magnitude of the disease. Intracellular pathogens colonize a variety of anatomical locations that are likely to be scarce in micronutrients, as a defense strategy adopted by the host, known as nutritional immunity. Indispensable critical micronutrients are required both by the host and by C. albicans, especially as a cofactor in important metabolic functions. Since these micronutrients are not freely available, C. albicans need to exploit host reservoirs to adapt within the host for survival. The ability of pathogenic organisms, including C. albicans, to sense and adapt to limited micronutrients in the hostile environment is essential for survival and confers the basis of its success as a pathogen. This review describes that micronutrients availability to C. albicans is a key attribute that may be exploited when one considers designing strategies aimed at disrupting MDR in this pathogenic fungi. Here, we discuss recent advances that have been made in our understanding of fungal micronutrient acquisition and explore the probable pathways that may be utilized as targets.