Enhanced Antibacterial and Antiadhesive Activities of Silver-PTFE Nanocomposite Coating for Urinary Catheters

Fabrication of PTFE + TiO2/Ag coatings on 316L/polydopamine with advanced mechanical, bio-corrosion, and antibacterial properties for stainless steel Catheters

This study explores the corrosion resistance and antibacterial properties of a PTFE + TiO2/Ag coating applied to 316 L stainless steel. To enhance adhesion, a polydopamine interlayer was chemically deposited onto the steel surface. The PTFE + TiO2 coating was subsequently applied through immersion, followed by the deposition of silver nanoparticles using a chemical method. Optimization of the polydopamine interlayer involved varying temperature, time, stirring speed, and drying parameters. The optimal conditions for the polydopamine interlayer were determined to be 60 °C for 1 h, 300 rpm stirring, and 24-h drying in a freeze dryer. Analytical results demonstrated that both the PTFE + TiO2 and PTFE/PTFE + TiO2/Ag coatings exhibited exceptional corrosion resistance, with corrosion currents of 3.3 × 10-5 and 3.2 × 10-4 μA/cm2, respectively. Antibacterial assessments showcased the remarkable ability of the PTFE/PTFE + TiO2/Ag coating, containing 5% silver content, to effectively inhibit bacterial penetration within a 6.5 mm radius. Furthermore, this coating displayed a water contact angle of 143°, classifying it as a hydrophobic coating. The photocatalytic efficiency (Rs) was determined to be 3.18 × 10-3 A/W, a performance level comparable to that of a standard UV sensor. These findings underscore the substantial enhancements in corrosion resistance, antibacterial performance, and hydrophobic characteristics achieved with the PTFE + TiO2/Ag coating, particularly through the novel optimization of the polydopamine interlayer. This coating exhibits great promise for multifunctional protective applications in diverse fields, particularly demonstrating its suitability for implants and bio-coatings.

Long-Lasting Antibacterial PDMS Surfaces Constructed from Photocuring of End-Functionalized Polymers

A challenge remains in the development of anti-infectious coatings for the inert surfaces of biomedical devices that are prone to bacterial colonization and biofilm formation. Here, a facile photocuring method to construct functionalized polymeric coatings on inert polydimethylsiloxane (PDMS) surfaces, is developed. Using atom transfer radical polymerization (ATRP) initiator bearing thymol group, hydrophilic DMAEMA and benzophenone (BP)-containing monomers are copolymerized to form polymers with end functional groups. An end-functionalized biocidal coating is then constructed on the inert PDMS surface in one step using a photocuring reaction. The functionalized PDMS surfaces show excellent antibacterial and antifouling properties, are capable of completely eradiating MRSA within ≈6 h, and effectively inhibit the growth of biofilms. In addition, they have good stability and long-lasting antibacterial activity in body fluid environments such as 0.9% saline and urine. According to bladder model experiments, the catheter's lifespan can be extended from ≈7 to 35 days by inhibiting the growth and migration of bacteria along its inner surface. The photocuring technique is therefore very promising in terms of surface functionalization of inert biomedical devices in order to minimize the spread of infection.

Conferring NiTi alloy with controllable antibacterial activity and enhanced corrosion resistance by exploiting Ag@PDA films as a platform through a one-pot construction route

The lack of antibacterial activity and the leaching of Ni ions seriously limit the potential applications of the near equiatomic nickel-titanium (NiTi) alloy in the biomedical field. In this study, a silver nanoparticles (Ag NPs) wrapped in a polydopamine (Ag@PDA) film modified NiTi alloy with controllable antibacterial activity and enhanced corrosion resistance was achieved using a one-pot approach in a mixed solution of AgNO3 and dopamine. The controllable antibacterial activity could be achieved by adjusting the initial concentration of dopamine (Cdop), which obtained Ag@PDA films with varying thickness of polydopamine layers coated on Ag NPs, thereby conferring different levels of antibacterial activity to the modified NiTi alloy. In vitro antibacterial ratios (24 h) of Ag@PDA film-modified NiTi alloy against E.coli and S.aureus ranged from 46 % to 100 % and from 42 % to 100 %, respectively. The release curves of Ag ions indicated the persistent antibacterial effect of Ag@PDA film-modified NiTi alloy for at least 21 days. Moreover, in vitro cytotoxicity and in vivo implantation tests demonstrated the satisfactory biosafety of the Ag@PDA film-modified NiTi alloy when used as bioimplants. This research offers valuable insight into meeting various antibacterial demands for NiTi alloy implantations and highlights the potential of Ag-containing film-modified biomaterials in addressing different types of infections induced by implantations.

Piezoelectrically-activated antibacterial catheter for prevention of urinary tract infections in an on-demand manner

Catheter-associated urinary tract infection (CAUTI) is a common clinical problem, especially during long-term catheterization, causing additional pain to patients. The development of novel antimicrobial coatings is needed to prolong the service life of catheters and reduce the incidence of CAUTIs. Herein, we designed an antimicrobial catheter coated with a piezoelectric zinc oxide nanoparticles (ZnO NPs)-incorporated polyvinylidene difluoride-hexafluoropropylene (ZnO-PVDF-HFP) membrane. ZnO-PVDF-HFP could be stably coated onto silicone catheters simply by a one-step solution film-forming method, very convenient for industrial production. In vitro, it was demonstrated that ZnO-PVDF-HFP coating could significantly inhibit bacterial growth and the formation of bacterial biofilm under ultrasound-mediated mechanical stimulation even after 4 weeks. Importantly, the on and off of antimicrobial activity as well as the strenth of antibacterial property could be controlled in an adaptive manner via ultrasound. In a rabbit model, the ZnO-PVDF-HFP-coated catheter significantly reduced the incidence CAUTIs compared with clinically-commonly used catheters under assistance of ultrasonication, and no side effect was detected. Collectively, the study provided a novel antibacterial catheter to prevent the occurrence of CAUTIs, whose antibacterial activity could be controlled in on-demand manner, adaptive to infection situation and promising in clinical application.

Generalized Multifunctional Coating Strategies Based on Polyphenol-Amine-Inspired Chemistry and Layer-by-Layer Deposition for Blood Contact Catheters

Blood-contacting catheters play a pivotal role in contemporary medical treatments, particularly in the management of cardiovascular diseases. However, these catheters exhibit inappropriate wettability and lack antimicrobial characteristics, which often lead to catheter-related infections and thrombosis. Therefore, there is an urgent need for blood contact catheters with antimicrobial and anticoagulant properties. In this study, we employed tannic acid (TA) and 3-aminopropyltriethoxysilane (APTES) to create a stable hydrophilic coating under mild conditions. Heparin (Hep) and poly(lysine) (PL) were then modified on the TA-APTES coating surface using the layer-by-layer (LBL) technique to create a superhydrophilic TA/APTES/(LBL)4 coating on silicone rubber (SR) catheters. Leveraging the superhydrophilic nature of this coating, it can be effectively applied to blood-contacting catheters to impart antibacterial, antiprotein adsorption, and anticoagulant properties. Due to Hep's anticoagulant attributes, the activated partial thromboplastin time and thrombin time tests conducted on SR/TA-APTES/(LBL)4 catheters revealed remarkable extensions of 276 and 103%, respectively, when compared to uncoated commercial SR catheters. Furthermore, the synergistic interaction between PL and TA serves to enhance the resistance of SR/TA-APTES/(LBL)4 catheters against bacterial adherence, reducing it by up to 99.9% compared to uncoated commercial SR catheters. Remarkably, the SR/TA-APTES/(LBL)4 catheter exhibits good biocompatibility with human umbilical vein endothelial cells in culture, positioning it as a promising solution to address the current challenges associated with blood-contact catheters.

Medical Device-Associated Biofilm Infections and Multidrug-Resistant Pathogens

Medical devices such as venous catheters (VCs) and urinary catheters (UCs) are widely used in the hospital setting. However, the implantation of these devices is often accompanied by complications. About 60 to 70% of nosocomial infections (NIs) are linked to biofilms. The main complication is the ability of microorganisms to adhere to surfaces and form biofilms which protect them and help them to persist in the host. Indeed, by crossing the skin barrier, the insertion of VC inevitably allows skin flora or accidental environmental contaminants to access the underlying tissues and cause fatal complications like bloodstream infections (BSIs). In fact, 80,000 central venous catheters-BSIs (CVC-BSIs)-mainly occur in intensive care units (ICUs) with a death rate of 12 to 25%. Similarly, catheter-associated urinary tract infections (CA-UTIs) are the most commonlyhospital-acquired infections (HAIs) worldwide.These infections represent up to 40% of NIs.In this review, we present a summary of biofilm formation steps. We provide an overview of two main and important infections in clinical settings linked to medical devices, namely the catheter-asociated bloodstream infections (CA-BSIs) and catheter-associated urinary tract infections (CA-UTIs), and highlight also the most multidrug resistant bacteria implicated in these infections. Furthermore, we draw attention toseveral useful prevention strategies, and advanced antimicrobial and antifouling approaches developed to reduce bacterial colonization on catheter surfaces and the incidence of the catheter-related infections.

Comparison of Superhydrophilic, Liquid-Like, Liquid-Infused, and Superhydrophobic Surfaces in Preventing Catheter-Associated Urinary Tract Infection and Encrustation

Over the past decade, superhydrophilic zwitterionic surfaces, slippery liquid-infused porous surfaces, covalently attached liquid-like surfaces, and superhydrophobic surfaces have emerged as the most promising strategies to prevent biofouling on biomedical devices. Despite working through different mechanisms, they have demonstrated superior efficacy in preventing the adhesion of biomolecules (e.g., proteins and bacteria) compared with conventional material surfaces. However, their potential in combating catheter-associated urinary tract infection (CAUTI) remains uncertain. In this research, we present the fabrication of these four coatings for urinary catheters and conduct a comparative assessment of their antifouling properties through a stepwise approach. Notably, the superhydrophilic zwitterionic coating demonstrated the highest antifouling activity, reducing 72.3% of fibrinogen deposition and over 75% of bacterial adhesion (Escherichia coli and Staphylococcus aureus) when compared with an uncoated polyvinyl chloride (PVC) surface. The zwitterionic coating also exhibited robust repellence against blood and improved surface lubricity, decreasing the dynamic coefficient of friction from 0.63 to 0.35 as compared with the PVC surface. Despite the fact that the superhydrophilic zwitterionic and hydrophobic liquid-like surfaces showed great promise in retarding crystalline biofilm formation in the presence of Proteus mirabilis, it is worth noting that their long-term antifouling efficacy may be compromised by the proliferation and migration of colonized bacteria as they are unable to kill them or inhibit their swarming. These findings underscore both the potential and limitations of these ultralow fouling materials as urinary catheter coatings for preventing CAUTI.

Perfluoropolyether-incorporated polyurethane with enhanced antibacterial and anti-adhesive activities for combating catheter-induced infection

To avoid the undesired bacterial attachment on polyurethane-based biomedical devices, we designed a class of novel perfluoropolyether-incorporated polyurethanes (PFPU) containing different contents of perfluoropolyether (PFPE) segments. After blending with Ag nanoparticles (AgNPs), a series of bifunctional PFPU/AgNPs composites with bactericidal and anti-adhesion abilities were obtained and correspondingly made into PFPU/AgNPs films (PFPU/Ag-F) using a simple solvent-casting method. Due to its highest hydrophobicity and suitable mechanical properties, PFPU8/Ag-F containing 8 mol% of PFPE content was chosen as the optimized one for the next antibacterial assessment. The PFPU8/Ag-F can effectively deactivate over 99.9% of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) cells at 106 CFU mL-1 within 30 min. Furthermore, the PFPU8/AgNPs composite was used as painting material to form a protective coating for the commercial polyurethane (PU) catheter. The as-prepared PFPU8/Ag coating exhibits high resistance to bacterial adhesion in a continuous-flow artificial urine model in an 8 day exposure. Therefore, it can be expected that the proposed PFPE-containing films and coatings can effectively prevent bacterial colonization and biofilm formation on catheters or other implants, thereby reducing the risk of postoperative catheter-induced infection.

Polyvinylpyrrolidone hydrogel coating for ureteral stent: Safety and performance evaluation

BACKGROUND

Ureteral stents are commonly used in urology. However, complications such as encrustation and infection on the surface of the stent, and injury to the ureteral mucosa can occur after implantation, causing discomfort for patients.

OBJECTIVE

We intend to confirm the biosafety of polyvinylpyrrolidone (PVP) hydrophilic coating and its lubrication properties for surface modification of ureteral stents to reduce friction and improve patient comfort.

METHODS

Based on our previous studies, we have developed a PVP hydrophilic coating for surface modification of ureteral stents. We firstly investigated the cytotoxicity, intradermal irritation, delayed type hypersensitivity, and acute systemic reactions of stent coating extracts. We further characterized the break strength, retention strength, and dynamic friction of the stent.

RESULTS

The cell survival rate of all experimental groups was greater than 70%. No hypersensitivity reaction, systemic toxicity reaction, or obvious intradermal reaction were observed. The above results indicate that the test results of the modified stent meet the requirements of ISO 10993-5: 2009 (Cytotoxicity); ISO 10993-10:2021 (Sensitization and Irritation); ISO 10993-11:2017 (Acute Systemic Toxicity). After soaking in artificial urine for an extended period, there was no obvious change in its super-slip performance.

CONCLUSION

Our results confirm the safety and lubrication characteristics of PVP hydrophilic coating for ureteral stent surface modification. The performance of this coating has the potential to reduce complications after stent implantation, thereby improving patient comfort, reducing medical burden, and has a good clinical application prospect.

Novel Antibacterial Agents SAAP-148 and Halicin Combat Gram-Negative Bacteria Colonizing Catheters

The antibiotic management of catheter-related infections (CRIs) often fails owing to the emergence of antimicrobial-resistant strains and/or biofilm/persister apparitions. Thus, we investigated the efficacy of two novel antimicrobial agents, i.e., the synthetic peptide SAAP-148 and the novel antibiotic halicin, against Gram-negative bacteria (GNB) colonizing catheters. The antibacterial, anti-biofilm, and anti-persister activities of both agents were evaluated against Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae strains. The enrolled strains were isolated from catheters and selected based on their resistance to at least three antibiotic classes and biofilm formation potential. Furthermore, the hemolysis and endotoxin neutralization abilities of these agents were explored. The bactericidal activity of both agents was reduced in urine and plasma as compared to buffered saline. In a dose-dependent manner, SAAP-148 and halicin reduced bacterial counts in 24 h preformed biofilms on silicone elastomer discs and eliminated persisters originating from antibiotic-exposed mature 7-day biofilms, with halicin being less effective than SAAP-148. Importantly, SAAP-148 and halicin acted synergistically on E. coli and K. pneumoniae biofilms but not on A. baumannii biofilms. The peptide, but not halicin, decreased the production of IL-12p40 upon exposure to UV-killed bacteria. This preliminary study showed that SAAP-148 and halicin alone/in combination are promising candidates to fight GNB colonizing catheters.

Emerging evidence-based innovative approaches to control catheter-associated urinary tract infection: a review

Healthcare settings have dramatically advanced the latest medical devices, such as urinary catheters (UC) for infection, prevention, and control (IPC). The continuous or intermittent flow of a warm and conducive (urine) medium in the medical device, the urinary catheter, promotes the formation of biofilms and encrustations, thereby leading to the incidence of CAUTI. Additionally, the absence of an innate immune host response in and around the lumen of the catheter reduces microbial phagocytosis and drug action. Hence, the review comprehensively overviews the challenges posed by CAUTI and associated risks in patients' morbidity and mortality. Also, detailed, up-to-date information on the various strategies that blended/tailored the surface properties of UC to have anti-fouling, biocidal, and anti-adhesive properties to provide an outlook on how they can be better managed with futuristic solutions.

Fabrication of antibacterial polydopamine-carboxymethyl cellulose-Ag nanoparticle hydrogel coating for urinary catheters

Urinary tract infections caused by catheter insertion are prevalent in hospital clinics, which can induce serious complications such as bacteriuria and sepsis, and even lead to patient death. The disposable catheters currently used in clinical practice suffer from poor biocompatibility and high infection rate. In this paper, we developed a polydopamine (PDA)-carboxymethylcellulose (CMC)-Ag nanoparticles (AgNPs) coating with both good antibacterial and anti-adhesion properties to bacteria on the surfaces of a disposable medical latex catheter by a simple dipping method. The antibacterial efficiency of the coated catheters against Gram-negative E. coli and Gram-positive S. aureus bacteria was evaluated with both inhibition zone tests and fluorescence microscopy. Compared with the untreated catheter, the PDA-CMC-AgNPs coated catheters showed both good antibacterial and anti-adhesion properties to bacteria, which inhibited the adhesion of live bacteria and dead bacteria by 99.0% and 86.6%, respectively. This novel PDA-CMC-AgNPs composite hydrogel coating has great potential in applications in catheters and other biomedical devices to reduce infections.

Understanding bacterial biofilms: From definition to treatment strategies

Bacterial biofilms are complex microbial communities encased in extracellular polymeric substances. Their formation is a multi-step process. Biofilms are a significant problem in treating bacterial infections and are one of the main reasons for the persistence of infections. They can exhibit increased resistance to classical antibiotics and cause disease through device-related and non-device (tissue) -associated infections, posing a severe threat to global health issues. Therefore, early detection and search for new and alternative treatments are essential for treating and suppressing biofilm-associated infections. In this paper, we systematically reviewed the formation of bacterial biofilms, associated infections, detection methods, and potential treatment strategies, aiming to provide researchers with the latest progress in the detection and treatment of bacterial biofilms.

Can Superhydrophobic PET Surfaces Prevent Bacterial Adhesion?

Prevention of bacterial adhesion is a way to reduce and/or avoid biofilm formation, thus restraining its associated infections. The development of repellent anti-adhesive surfaces, such as superhydrophobic surfaces, can be a strategy to avoid bacterial adhesion. In this study, a polyethylene terephthalate (PET) film was modified by in situ growth of silica nanoparticles (NPs) to create a rough surface. The surface was further modified with fluorinated carbon chains to increase its hydrophobicity. The modified PET surfaces presented a pronounced superhydrophobic character, showing a water contact angle of 156° and a roughness of 104 nm (a considerable increase comparing with the 69° and 4.8 nm obtained for the untreated PET). Scanning Electron Microscopy was used to evaluate the modified surfaces morphology, further confirming its successful modification with nanoparticles. Additionally, a bacterial adhesion assay using an Escherichia coli expressing YadA, an adhesive protein from Yersinia so-called Yersinia adhesin A, was used to assess the anti-adhesive potential of the modified PET. Contrarily to what was expected, adhesion of E. coli YadA was found to increase on the modified PET surfaces, exhibiting a clear preference for the crevices. This study highlights the role of material micro topography as an important attribute when considering bacterial adhesion.

Recent nanotechnology-based strategies for interfering with the life cycle of bacterial biofilms

Biofilm formation plays an important role in the resistance development in bacteria to conventional antibiotics. Different properties of the bacterial strains within biofilms compared with their planktonic states and the protective effect of extracellular polymeric substances contribute to the insusceptibility of bacterial cells to conventional antimicrobials. Although great effort has been devoted to developing novel antibiotics or synthetic antibacterial compounds, their efficiency is overshadowed by the growth of drug resistance. Developments in nanotechnology have brought various feasible strategies to combat biofilms by interfering with the biofilm life cycle. In this review, recent nanotechnology-based strategies for interfering with the biofilm life cycle according to the requirements of different stages are summarized. Additionally, the importance of strategies that modulate the bacterial biofilm microenvironment is also illustrated with specific examples. Lastly, we discussed the remaining challenges and future perspectives on nanotechnology-based strategies for the treatment of bacterial infection.

Felix D, Yeh HH, Luo HD, Moskalev I, Wang Q, Wang R, Grecov D, Fazli L, Lange D, Kizhakkedathu JN. Robust Nanoparticle-Derived Lubricious Antibiofilm Coating for Difficult-to-Coat Medical Devices with Intricate Geometry

A major medical device-associated complication is the biofilm-related infection post-implantation. One promising approach to prevent this is to coat already commercialized medical devices with effective antibiofilm materials. However, developing a robust high-performance antibiofilm coating on devices with a nonflat geometry remains unmet. Here, we report the development of a facile scalable nanoparticle-based antibiofilm silver composite coating with long-term activity applicable to virtually any objects including difficult-to-coat commercially available medical devices utilizing a catecholic organic-aqueous mixture. Using a screening approach, we have identified a combination of the organic-aqueous buffer mixture which alters polycatecholamine synthesis, nanoparticle formation, and stabilization, resulting in controlled deposition of in situ formed composite silver nanoparticles in the presence of an ultra-high-molecular-weight hydrophilic polymer on diverse objects irrespective of its geometry and chemistry. Methanol-mediated synthesis of polymer-silver composite nanoparticles resulted in a biocompatible lubricious coating with high mechanical durability, long-term silver release (∼90 days), complete inhibition of bacterial adhesion, and excellent killing activity against a diverse range of bacteria over the long term. Coated catheters retained their excellent activity even after exposure to harsh mechanical challenges (rubbing, twisting, and stretching) and storage conditions (>3 months stirring in water). We confirmed its excellent bacteria-killing efficacy (>99.999%) against difficult-to-kill bacteria (Proteus mirabilis) and high biocompatibility using percutaneous catheter infection mice and subcutaneous implant rat models, respectively, in vivo. The developed coating approach opens a new avenue to transform clinically used medical devices (e.g., urinary catheters) to highly infection-resistant devices to prevent and treat implant/device-associated infections.

Fibrinogen Deposition on Silicone Oil-Infused Silver-Releasing Urinary Catheters Compromises Antibiofilm and Anti-Encrustation Properties

Slippery silicone-oil-infused (SOI) surfaces have recently emerged as a promising alternative to conventional anti-infection coatings for urinary catheters to combat biofilm and encrustation formation. Benefiting from the ultralow low hysteresis and slippery behavior, the liquid-like SOI coatings have been found to effectively reduce bacterial adhesion under both static and flow conditions. However, in real clinical settings, the use of catheters may also trigger local inflammation, leading to release of host-secreted proteins, such as fibrinogen (Fgn) that deposits on the catheter surfaces, creating a niche that can be exploited by uropathogens to cause infections. In this work, we report on the fabrication of a silicone oil-infused silver-releasing catheter which exhibited superior durability and robust antibacterial activity in aqueous conditions, reducing biofilm formation of two key uropathogens Escherichia coli and Proteus mirabilis by ∼99%, when compared with commercial all-silicone catheters after 7 days while remaining noncytotoxic toward L929 mouse fibroblasts. After exposure to Fgn, the oil-infused surfaces induced conformational changes in the protein which accelerated adsorption onto the surfaces. The deposited Fgn blocked the interaction of silver with the bacteria and served as a scaffold, which promoted bacterial colonization, resulting in a compromised antibiofilm activity. Fgn binding also facilitated the migration of Proteus mirabilis over the catheter surfaces and accelerated the deposition and spread of crystalline biofilm. Our findings suggest that the use of silicone oil-infused silver-releasing urinary catheters may not be a feasible strategy to combat infections and associated complications arising from severe inflammation.

SiO2 nanosphere coated tough catheter with superhydrophobic surface for improving the antibacteria and hemocompatibility

Catheter infection is the most common complication after vascular catheter placement, which seriously threatens the survival of critically ill patients. Although catheters with antibacterial drug coatings have been used, catheter infections have not been effectively resolved. In this research, a SiO₂ nanosphere-coated PTFE catheter (PTFE-SiO₂) with enhanced antibacterial and excellent mechanical properties was prepared via dopamine as a graft bridge. The microscopic morphology results show that the nanospheres are uniformly dispersed on the surface of the catheter. The physicochemical characterization confirmed that PTFE-SiO₂ had reliable bending resistance properties, superhydrophobicity, and cytocompatibility and could inhibit thrombosis. Antibacterial results revealed that PTFE-SiO₂ could hinder the reproduction of E. coli and S. aureus. This research demonstrates the hydroxyl-rich materials obtained by hydroboration oxidation have the advantages of better dispersion of functional coatings, indicating their potential for helpful modification of catheters.

The Development of New Nanocomposite Polytetrafluoroethylene/Fe2O3 NPs to Prevent Bacterial Contamination in Meat Industry

The bacterial contamination of cutting boards and other equipment in the meat processing industry is one of the key reasons for reducing the shelf life and consumer properties of products. There are two ways to solve this problem. The first option is to create coatings with increased strength in order to prevent the formation of micro damages that are favorable for bacterial growth. The second possibility is to create materials with antimicrobial properties. The use of polytetrafluoroethylene (PTFE) coatings with the addition of metal oxide nanoparticles will allow to the achieving of both strength and bacteriostatic effects at the same time. In the present study, a new coating based on PTFE and Fe₂O₃ nanoparticles was developed. Fe₂O₃ nanoparticles were synthesized by laser ablation in water and transferred into acetone using the developed procedures. An acetone-based colloidal solution was mixed with a PTFE-based varnish. Composites with concentrations of Fe₂O₃ nanoparticles from 0.001-0.1% were synthesized. We studied the effect of the obtained material on the generation of ROS (hydrogen peroxide and hydroxyl radicals), 8-oxoguanine, and long-lived active forms of proteins. It was found that PTFE did not affect the generation of all the studied compounds, and the addition of Fe₂O₃ nanoparticles increased the generation of H₂O₂ and hydroxyl radicals by up to 6 and 7 times, respectively. The generation of 8-oxoguanine and long-lived reactive protein species in the presence of PTFE/Fe₂O₃ NPs at 0.1% increased by 2 and 3 times, respectively. The bacteriostatic and cytotoxic effects of the developed material were studied. PTFE with the addition of Fe₂O₃ nanoparticles, at a concentration of 0.001% or more, inhibited the growth of E. coli by 2-5 times compared to the control or PTFE without NPs. At the same time, PTFE, even with the addition of 0.1% Fe₂O₃ nanoparticles, did not significantly impact the survival of eukaryotic cells. It was assumed that the resulting composite material could be used to cover cutting boards and other polymeric surfaces in the meat processing industry.

A Polytetrafluoroethylene (PTFE) and Nano-Al2O3 Based Composite Coating with a Bacteriostatic Effect against E. coli and Low Cytotoxicity

The problem of bacterial contamination through surfaces is important for the food industry. In this regard, there is a growing interest in new coatings based on nanoparticles that can provide a long-term antibacterial effect. Aluminum oxide nanoparticles are a good candidate for such coatings due to their availability and good biocompatibility. In this study, a coating containing aluminum oxide nanoparticles was produced using polytetrafluoroethylene as a polymer matrix-a polymer that exhibits excellent mechanical and physicochemical properties and it is not toxic. The obtained coatings based on "liquid Teflon" containing various concentrations of nanoparticles (0.001-0.1 wt%) prevented the bacterial growth, and they did not exhibit a cytotoxicity on animal cells in vitro. Such coatings are designed not only to provide an antibacterial surface effect, but also to eliminate micro damages on surfaces that inevitably occur in the process of food production.

Silicone Foley catheters impregnated with microbial indole derivatives inhibit crystalline biofilm formation by Proteus mirabilis

Proteus mirabilis is a common causative agent for catheter-associated urinary tract infections (CAUTI). The crystalline biofilm formation by P. mirabilis causes catheter encrustation and blockage leading to antibiotic treatment resistance. Thus, biofilm formation inhibition on catheters becomes a promising alternative for conventional antimicrobial-based treatment that is associated with rapid resistance development. Our previous work has demonstrated the in vitro antibiofilm activity of microbial indole derivatives against clinical isolates of P. mirabilis. Accordingly, we aim to evaluate the capacity of silicone Foley catheters (SFC) impregnated with these indole derivatives to resist biofilm formation by P. mirabilis both phenotypically and on the gene expression level. Silicon Foley catheter was impregnated with indole extract recovered from the supernatant of the rhizobacterium Enterobacter sp. Zch127 and the antibiofilm activity was determined against P. mirabilis (ATCC 12435) and clinical isolate P8 cultured in artificial urine. The indole extract at sub-minimum inhibitory concentration (sub-MIC=0.5X MIC) caused a reduction in biofilm formation as exhibited by a 60-70% reduction in biomass and three log₁₀ in adhered bacteria. Results were confirmed by visualization by scanning electron microscope. Moreover, changes in the relative gene expression of the virulence genes confirmed the antibiofilm activity of the indole extract against P. mirabilis. Differential gene expression analysis showed that extract Zch127 at its sub-MIC concentration significantly down-regulated genes associated with swarming activity: umoC, flhC, flhD, flhDC, and mrpA (p< 0.001). In addition, Zch127 extract significantly down-regulated genes associated with polyamine synthesis: speB and glnA (p< 0.001), as well as the luxS gene associated with quorum sensing. Regulatory genes for capsular polysaccharide formation; rcsB and rcsD were not significantly affected by the presence of the indole derivatives. Furthermore, the impregnated catheters and the indole extract showed minimal or no cytotoxic effect against human fibroblast cell lines indicating the safety of this intervention. Thus, the indole-impregnated catheter is proposed to act as a suitable and safe strategy for reducing P. mirabilis CAUTIs.

Green synthesis of silver nanoparticles and their antibacterial effects

Antibacterial resistance is by far one of the greatest challenges to global health. Many pharmaceutical or material strategies have been explored to overcome this dilemma. Of these, silver nanoparticles (AgNPs) are known to have a non-specific antibacterial mechanism that renders it difficult to engender silver-resistant bacteria, enabling them to be more powerful antibacterial agents than conventional antibiotics. AgNPs have shown promising antibacterial effects in both Gram-positive and Gram-negative bacteria. The aim of this review is to summarize the green synthesis of AgNPs as antibacterial agents, while other AgNPs-related insights (e.g., antibacterial mechanisms, potential toxicity, and medical applications) are also reviewed.

Enabling Antibacterial and Antifouling Coating via Grafting of a Nitric Oxide-Releasing Ionic Liquid on Silicone Rubber

Infections caused by bacteria and biofilms on the surfaces of biomedical devices and implants pose serious threats to public health. Herein, a nitric oxide (NO) gas-releasing quaternary ammonium-type ionic liquid (IL)-based coating on polydimethylsiloxane (PDMS), PDIL-NO, with effective and long-acting antibacterial and antifouling properties was prepared. N-(2-((2, 3-Dimethylbut-3-enoyl)oxy)ethyl)-N, N-dimethyloctan-1-aminium bromide (IL-Br), and 2-methyl-2-propenoic acid 2-(2-methoxyethoxy) ethyl ester were covalently grafted onto the surfaces of PDMS by a thiol-ene click chemical reaction, followed by incorporation of l-proline anions (Pro^-) through anion exchange with Br^- to adsorb NO gas. The prepared PDIL-NO showed a prolonged NO-releasing time (>1440 min) and a relatively high concentration (88 μM). Additionally, PDIL-NO possessed good and long-term antimicrobial activity, and could effectively reduce the adsorption of bovine serum albumin and adhesion of bacteria, as well as inhibit wound infection and reduce inflammation in vivo due to the synergetic effect of IL and the released NO. This study may provide a new approach to combat bacterial infections associated with biomedical devices and implants.

Fungal-derived Selenium Nanoparticles and Their Potential Applications in Electroless Silver Coatings for Preventing Pin-tract Infections

Pin-tract infections (PTIs) are a common complication of external fixation of fractures and current strategies for preventing PTIs have proven to be ineffective. Recent advances show that the use of anti-infection coatings with local antibacterial activity may solve this problem. Selenium has been considered as a promising anti-infection agent owing to its antibacterial and antibiofilm activities. In this study, selenium nanoparticles (SeNPs) were synthesized via a cost-effective fungi-mediated biorecovery approach and demonstrated excellent stability and homogeneity. To investigate their anti-infection potential, the SeNPs were doped in silver coatings through an electroless plating process and the silver–selenium (Ag–Se) coatings were tested for antibacterial and antibiofilm properties against Staphylococcus aureus F1557 and Escherichia coli WT F1693 as well as corrosion resistance in simulated body fluid. It was found that the Ag–Se coating significantly inhibited S.aureus growth and biofilm formation on the surface, reducing 81.2% and 59.7% of viable bacterial adhesion when compared with Ag and Ag–PTFE-coated surfaces after 3 days. The Ag–Se coating also exhibited improved corrosion resistance compared with the Ag coating, leading to a controlled release of Ag⁺, which in turn reduced the risk of cytotoxicity against hFOBs. These results suggest that the fungal-derived SeNPs may have potential in use as implant coatings to prevent PTIs.

Potent, Broad-Spectrum Antimicrobial Effects of S-Nitroso-N-acetylpenicillamine-Impregnated Nitric Oxide-Releasing Latex Urinary Catheters

Although numerous prevention and intervention techniques have been developed to counteract catheter-associated urinary tract infections (CAUTIs), urinary catheters remain one of the most common sources of hospital-acquired infections. Nitric oxide (NO), a gaseous free radical responsible for regulating many physiological functions in the body, has gained immense popularity due to its potent, broad-spectrum antimicrobial activity, which is capable of combating medical device-associated infections. In this work, a straightforward solvent-swelling method was used to load the NO donor S-nitroso-N-acetyl-penicillamine (SNAP) into commercial latex catheters (SNAP-UCs) for the first time. The effects of swelling catheters with different concentrations of SNAP solutions (25-125 mg/mL SNAP in tetrahydrofuran (THF)) were studied by measuring the NO release kinetics, SNAP loading, and SNAP leaching. SNAP-UCs impregnated with a 50 mg/mL SNAP-THF solution were found to maximize the amount of SNAP loaded into the latex (0.115 ± 0.009 mg SNAP/mg catheter) and showed physiological levels of NO release (>2 × 10^-10 mol min^-1 cm^-2) over 7 days and minimal SNAP leaching (<2%). SNAP-UCs showed impressive in vitro contact-based and diffusible antimicrobial efficacy against three CAUTI-associated pathogens, reducing the viability of adhered and planktonic Escherichia coli, Proteus mirabilis, and Staphylococcus aureus by ∼98.0 to 99.1% (adhered) and 86.3-96.3% (planktonic) compared to control latex catheters. In vitro cytotoxicity against 3T3 mouse fibroblasts using a CCK-8 assay showed that SNAP-UCs were noncytotoxic (>90% viability). In summary, SNAP-UCs show stable, noncytotoxic NO release characteristics capable of potent, broad-spectrum antimicrobial activity, demonstrating great potential for reducing the devastating effects associated with CAUTIs.

Silver-titanium polymeric nanocomposite non ecotoxic with bactericide activity

In view of the intense interest in applications of silver nanoparticles in products for the medical field and in food preservation packaging due to their antimicrobial properties, the ecotoxicology of silver nanocomposites was evaluated in films. Test with the sea urchin Echinometra lucunter, to evaluate embryonic development and contamination by the action of silver and titanium nanoparticles in polyethylene nanocomposite films presents new results. The silver nanoparticle’s stability in polymeric materials can be enhanced by adding carriers, such as titanium dioxide and montmorillonite clay (MMT) without to producing one unfriendly material. For this research, low-density polyethylene (LDPE)/linear low-density polyethylene (LLDPE) were used processed in a twin-screw extruder, followed by gamma irradiation with 25 kGy and characterized by ecotoxicology assays, field emission scanning electron microscopy (FESEM), scanning electron microscopy and energy dispersive spectroscopy (SEM–EDX), differential scanning calorimetry (DSC), thermogravimetric analysis (TG), Raman spectroscopy (SERS) and mechanical properties. The antibacterial properties of the LDPE films were investigated against Escherichia coli and Staphylococcus aureus. The gamma irradiation had an important effect in the synthesis of silver nanoparticles resulting in bactericidal activity and the death of 100% of the tested bacteria. The evaluation of the environment was considered with the ecotoxicological investigation carried out. The results indicated that the polymeric films with silver nanoparticles and TiO₂ do not contaminate the environment and neither interfere with the larval development of Echinometra lucunter. The obtained materials can be used in various applications with antimicrobial properties.

Gum acacia PEG iron oxide nanocomposite (GA-PEG-IONC) induced pharmacotherapeutic activity on the Las R gene expression of Pseudomonas aeruginosa and HOXB13 expression of prostate cancer (Pc 3) cell line. A green therapeutic approach of molecular mechanism inhibition

Among the diverse nanomaterials, polymer-based nanocomposites are gained more attention due to their high efficacy, target biological activities, biodegradability and biocompatibility-gum acacia (GA) - a polymer obtained from acacia trees-is considering the multifunctional nanocomposite synthesis. Distinctive Physico-chemical and biocompatibility properties of gum acacia are utilised to prepare a highly stable, biologically active, eco-friendly Nanocomposite. In this current investigation, gum acacia - poly ethylene glycol grafted iron oxide nanocomposite (GA-PEG-IONC) was synthesised by in situ green science principles. The synthesised Nanocomposite was evaluated against the molecular mechanism of urinary tract pathogenic bacterial strains and prostate cancer cells (Pc 3). Nanocomposite prepared in this examination exhibited notable structural, functional stability with nanoarchitecture which was affirmed by Fourier transform infrared spectroscopy (FTIR), electron microscopic studies, atomic force microscopy (AFM), vibrating sample magnetometric analysis (VSM) and X-ray diffraction (XRD), Synthesised Nanocomposite brought about notable antibacterial activity against urinary tract pathogenic strains by recording potential inhibitory effect on the expression of Las R gene. Inhibition of Las R gene expression reduced notable effect on biofilm development. Anticancer activity against prostate cancer cells (Pc3) was investigated by measurement of HOXB13 gene expression level. Inhibition of HOXB13 gene expression by the IONC brought about structural, functional changes. HOXB13 gene expression inhibition reveals a remarkable cytotoxic effect by recording decreased cell viability. Morphometric analysis by phase-contrast and DAPI fluorescence staining demonstrates that the Nanocomposite prompted cell morphology anomalies or apoptotic changes. Nanocomposite treatment brought about a good sign of Apoptosis by recording enhanced caspase 3 and 9 activities, DNA fragmentation and elevated reactive oxygen species generation (ROS). Hemocompatibility studies were carried out to determine the biocompatibility of the Nanocomposite. Spectrophotometric estimation of plasma haemoglobin, microscopic examination of whole blood cells shows the Nanocomposite was not inciting any indication of toxicity. These findings infer that IONC synthesised in the present study is the promising contender for a broad scope of biomedical applications, especially as an antibacterial and anticancer agent.

Broad spectrum antimicrobial PDMS-based biomaterial for catheter fabrication

Background

In addition to the widespread use of antibiotics in healthcare settings, the current COVID-19 pandemic has escalated the emergence of antibiotic resistance. Nosocomial infections among hospitalized patients is a leading site for such resistant microbial colonization due to prolonged use of invasive devices and antibiotics in therapies. Invasive medical devices, especially catheters, are prone to infections that could accelerate the development of resistant microbes. Often, catheters - particularly urinary catheters - are prone to high infection rates. Antibiotic-coated catheters can reduce infection rates and although commercially available, are limited in efficacy and choices.

Methods

Herein, a novel and facile method to fabricate PMDS-based biomaterial for the development of antimicrobial eluting catheters is presented. Silicone based organic polymer polydimethylsiloxane (PDMS) was used to prepare a biomaterial containing novel polymeric imidazolium antimicrobial compound.

Results

It was found that the PDMS-based biomaterials could eradicate microbial colonization even after 60 days in culture with continuous microbial challenge, be recycled over multiple uses, stored at room temperature for long-term usage and importantly is biocompatible.

Conclusion

The PDMS-based biomaterial displayed biocidal functionality on microbes of clinical origin, which form major threats in hospital acquired infections.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s40824-021-00235-5.

Current approaches for the exploration of antimicrobial activities of nanoparticles

Infectious diseases of bacterial and viral origins contribute to substantial mortality worldwide. Collaborative efforts have been underway between academia and the industry to develop technologies for a more effective treatment for such diseases. Due to their utility in various industrial applications, nanoparticles (NPs) offer promising potential as antimicrobial agents against bacterial and viral infections. NPs have been established to possess potent antimicrobial activities against various types of pathogens due to their unique characteristics and cell-damaging ability through several mechanisms. The recently accepted antimicrobial mechanisms possessed by NPs include metal ion release, oxidative stress induction, and non-oxidative mechanisms. Another merit of NPs lies in the low likelihood of the development of microbial tolerance towards NPs, given the multiple simultaneous mechanisms of action against the pathogens targeting numerous gene mutations in these pathogens. Moreover, NPs provide a fascinating opportunity to curb microbial growth before infections: this outstanding feature has led to their utilization as active antimicrobial agents in different industrial applications, e.g. the coating of medical devices, incorporation in food packaging, promoting wound healing and encapsulation with other potential materials for wastewater treatment. This review discusses the progress and achievements in the antimicrobial applications of NPs, factors contributing to their actions, mechanisms underlying their efficiency, and risks of their applications, including the antimicrobial action of metal nanoclusters (NCs). The review concludes with a discussion of the restrictions on present studies and future prospects of nanotechnology-based NPs development.

Advancements in release-active antimicrobial biomaterials: A journey from release to relief

Escalating medical expenses due to infectious diseases are causing huge socioeconomic pressure on mankind globally. The emergence of antibiotic resistance has further aggravated this problem. Drug-resistant pathogens are also capable of forming thick biofilms on biotic and abiotic surfaces to thrive in a harsh environment. To address these clinical problems, various strategies including antibacterial agent delivering matrices and bactericidal coatings strategies have been developed. In this review, we have discussed various types of polymeric vehicles such as hydrogels, sponges/cryogels, microgels, nanogels, and meshes, which are commonly used to deliver antibiotics, metal nanoparticles, and biocides. Compositions of these polymeric matrices have been elaborately depicted by elucidating their chemical interactions and potential activity have been discussed. On the other hand, various implant/device-surface coating strategies which exploit the release-active mechanism of bacterial killing are discussed in elaboration. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Cardiovascular Disease Implantable Materials and Surgical Technologies > Nanomaterials and Implants Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.

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.

Magnetic combi CLEA for inhibition of bacterial biofilm: A green approach

In the present study different enzymes (α- amylase, trypsin, cellulase, horse-radish peroxidase and pectinex ultra clear) were studied for bacterial biofilm inhibition and Pectinex ultra clear showed best inhibition. So, m-combi-CLEA of Pectinex ultra clear was developed by cross linked enzyme aggregate (CLEA) formation on APTES (3-aminopropyltriethoxysilane) modified iron oxide nanoparticles. Different parameters were optimized and it was observed that 0.4 mg/ml of protein (containing 25 U/mg cellulase activity), 0.5 mg/ml BSA and 10 mM glutaraldehyde when incubated for 3 h gives 100% enzyme activity using ethanol as the precipitant. The CLEA formed were thermally more stable as compared to free enzyme. m-combi-CLEA of Pectinex ultra clear shows 75-78% biofilm inhibition of E. coli and S. aureus. Furthermore, m-combi-CLEA can be reused till 4 cycles with same efficiency. The carbohydrate contents of E. coli biofilm decreased from 64.629 μg to 6.23 μg and for S. aureus biofilm, it decreased from 58.46 μg to 5.52 μg when treated with m-combi CLEA in comparison to untreated biofilms. FTIR, darkfield illumination Fluorescence Microscopy, and Scanning Electron Microscopy was further used for characterization.

The usage of composite nanomaterials in biomedical engineering applications

Nanotechnology is still developing over the decades and it is commonly used in biomedical applications with the design of nanomaterials due to the several purposes. With the investigation of materials on the molecular level has increased the develop composite nanomaterials with exceptional properties using in different applications and industries. The application of these composite nanomaterials is widely used in the fields of textile, chemical, energy, defense industry, electronics, and biomedical engineering which is growing and developing on human health. Development of biosensors for the diagnosis of diseases, drug targeting and controlled release applications, medical implants and imaging techniques are the research topics of nanobiotechnology. In this review, overview of the development of nanotechnology and applications which is use of composite nanomaterials in biomedical engineering is provided.

Reduced Crystalline Biofilm Formation on Superhydrophobic Silicone Urinary Catheter Materials

Crystalline biofilm formation in indwelling urinary catheters is a serious health problem as it creates a barrier for antibacterial coatings. This emphasizes the failure of antibacterial coatings that do not have a mechanism to reduce crystal deposition on catheter surfaces. In this study, trifluoropropyl spray-coated polydimethylsiloxane (TFP-PDMS) has been employed as an antibiofilm forming surface without any antibacterial agent. Here, TFP was coated on half-cured PDMS using the spray coating technique to obtain a durable superhydrophobic coating for a minimum five cycles of different sterilization methods. The crystalline biofilm-forming ability of Proteus mirabilis in artificial urine, under static and flow conditions, was assessed on a TFP-PDMS surface. In comparison to the commercially available silver-coated latex and silicone catheter surfaces, TFP-PDMS displayed reduced bacterial attachment over 14 days. Moreover, the elemental analysis determined by atomic absorption spectroscopy and energy-dispersive X-ray analysis revealed that the enhanced antibiofilm forming ability of TFP-PDMS was due to the self-cleaning activity of the surface. We believe that this modified surface will significantly reduce biofilm formation in indwelling urinary catheters and further warrant future clinical studies.

Marine Microbial-Derived Antibiotics and Biosurfactants as Potential New Agents against Catheter-Associated Urinary Tract Infections

Catheter-associated urinary tract infections (CAUTIs) are among the leading nosocomial infections in the world and have led to the extensive study of various strategies to prevent infection. However, despite an abundance of anti-infection materials having been studied over the last forty-five years, only a few types have come into clinical use, providing an insignificant reduction in CAUTIs. In recent decades, marine resources have emerged as an unexplored area of opportunity offering huge potential in discovering novel bioactive materials to combat human diseases. Some of these materials, such as antimicrobial compounds and biosurfactants synthesized by marine microorganisms, exhibit potent antimicrobial, antiadhesive and antibiofilm activity against a broad spectrum of uropathogens (including multidrug-resistant pathogens) that could be potentially used in urinary catheters to eradicate CAUTIs. This paper summarizes information on the most relevant materials that have been obtained from marine-derived microorganisms over the last decade and discusses their potential as new agents against CAUTIs, providing a prospective proposal for researchers.

Nanoparticles as Potential Novel Therapies for Urinary Tract Infections

Urinary tract infection (UTI) is one of the most common reasons for antibiotic treatment. Nevertheless, uropathogens are steadily becoming resistant to currently available therapies. In this context, nanotechnology emerges as an innovative and promising approach among diverse strategies currently under development. In this review we deeply discuss different nanoparticles (NPs) used in UTI treatment, including organic NPs, nanodiamonds, chemical and green synthesized inorganic NPs, and NPs made of composite materials. In addition, we compare the effects of different NPs against uropathogens in vivo and in vitro and discuss their potential impact the in the near future.

Bacteria Adhesion of Textiles Influenced by Wettability and Pore Characteristics of Fibrous Substrates

Bacteria adhesion on the surface is an initial step to create biofouling, which may lead to a severe infection of living organisms and humans. This study is concerned with investigating the textile properties including wettability, porosity, total pore volume, and pore size in association with bacteria adhesion. As model bacteria, Gram-negative, rod-shaped Escherichia coli and the Gram-positive, spherical-shaped Staphylococcus aureus were used to analyze the adhesion tendency. Electrospun webs made from polystyrene and poly(lactic acid) were used as substrates, with modification of wettability by the plasma process using either O2 or C4F8 gas. The pore and morphological characteristics of fibrous webs were analyzed by the capillary flow porometer and scanning electron microscopy. The substrate's wettability appeared to be the primary factor influencing the cell adhesion, where the hydrophilic surface resulted in considerably higher adhesion. The pore volume and the pore size, rather than the porosity itself, were other important factors affecting the bacteria adherence and retention. In addition, the compact spatial distribution of fibers limited the cell intrusion into the pores, reducing the total amount of adherence. Thus, superhydrophobic textiles with the reduced total pore volume and smaller pore size would circumvent the adhesion. The findings of this study provide informative discussion on the characteristics of fibrous webs affecting the bacteria adhesion, which can be used as a fundamental design guide of anti-biofouling textiles.

A Glance at Antimicrobial Strategies to Prevent Catheter-Associated Medical Infections

Urinary and intravascular catheters are two of the most used invasive medical devices; however, microbial colonization of catheter surfaces is responsible for most healthcare-associated infections (HAIs). Several antimicrobial-coated catheters are available, but recurrent antibiotic therapy can decrease their potential activity against resistant bacterial strains. The aim of this Review is to question the actual effectiveness of currently used (coated) catheters and describe the progress and promise of alternative antimicrobial coatings. Different strategies have been reviewed with the common goal of preventing biofilm formation on catheters, including release-based approaches using antibiotics, antiseptics, nitric oxide, 5-fluorouracil, and silver as well as contact-killing approaches employing quaternary ammonium compounds, chitosan, antimicrobial peptides, and enzymes. All of these strategies have given proof of antimicrobial efficacy by modifying the physiology of pathogens or disrupting their structural integrity. The aim for synergistic approaches using multitarget processes and the combination of both antifouling and bactericidal properties holds potential for the near future. Despite intensive research in biofilm preventive strategies, laboratorial studies still present some limitations since experimental conditions usually are not the same and also differ from biological conditions encountered when the catheter is inserted in the human body. Consequently, in most cases, the efficacy data obtained from in vitro studies is not properly reflected in the clinical setting. Thus, further well-designed clinical trials and additional cytotoxicity studies are needed to prove the efficacy and safety of the developed antimicrobial strategies in the prevention of biofilm formation at catheter surfaces.

Urinary Catheter Coating Modifications: The Race against Catheter-Associated Infections

Urinary catheters are common medical devices, whose main function is to drain the bladder. Although they improve patients’ quality of life, catheter placement predisposes the patient to develop a catheter-associated urinary tract infection (CAUTI). The catheter is used by pathogens as a platform for colonization and biofilm formation, leading to bacteriuria and increasing the risk of developing secondary bloodstream infections. In an effort to prevent microbial colonization, several catheter modifications have been made ranging from introduction of antimicrobial compounds to antifouling coatings. In this review, we discuss the effectiveness of different coatings in preventing catheter colonization in vitro and in vivo, the challenges in fighting CAUTIs, and novel approaches targeting host–catheter–microbe interactions.

Quantification Methods for Textile-Adhered Bacteria: Extraction, Colorimetric, and Microscopic Analysis

Quantification of bacteria adhered on porous, multi-layered fibers is a challenging task. The goal of this study is to compare different assessment procedures on counting textile-adhered bacteria, and to guide relevant analytical techniques. Three different methods were compared in measuring the amount of Escherichia coli (E. coli) adhered to polymeric film and fibrous nonwovens. In the extraction method, the adhered bacteria were released with the assistance of surfactant/enzyme, where the measurement was rather reproducible. For colorimetric method, stained bacteria enabled direct visualization without needing to detach cells from the surface, yet the linearity of color absorbency to cell counts was limited. The microscopic analysis provided direct observation of bacterial distribution over the surface, but accurate quantification was not possible for porous, fibrous surfaces. This study intends to help choosing a suitable test method to accurately quantify the textile-adhered bacteria, as well as broadly impact the research on anti-bioadhesive surfaces.