Silicone Catheters Research Articles

Protecting the Antibacterial Coating of Urinal Catheters for Improving Safety.

Catheter-associated urinary tract infections (CAUTI) are among the most common bacterial infections associated with prolonged hospitalization and increased healthcare expenditures. Despite recent advances in the prevention and treatment of these infections, there are still many challenges remaining, among them the creation of a durable catheter coating, which prevents bacterial biofilm formation. The current work reports on a method of protecting medical tubing endowed with antibiofilm properties. Silicone catheters coated sonochemically with ZnO nanoparticles (NPs) demonstrated excellent antibiofilm effects. Toward approval by the European Medicines Agency, it was realized that the ZnO coating would not withstand the regulatory requirements of avoiding dissolution for 14 days in artificial urine examination. Namely, after exposure to urine for 14 days, the coating amount was reduced by 90%. Additional coatings with either carbon or silica maintained antibiofilm activity against Staphylococcus aureus while resisting dissolution in artificial urine for 14 days (C- or SiO2-protected catheters exhibited only 29% reduction). HR-SEM images of the protected catheters indicate the presence of the ZnO coating as well as the protective layer. Antibiofilm activity of all catheters was evaluated both before and after exposure to artificial urine. It was shown that before artificial urine exposure, all coated catheters showed high antibiofilm properties compared to the uncoated control. Exposure of ZnO-coated catheters, without the protective layer, to artificial urine had a significant effect exhibited by the decrease in antibiofilm activity by almost 2 orders of magnitude, compared to unexposed catheters. Toxicity studies performed using a reconstructed human epidermis demonstrated the safety of the improved coating. Exposure of the epidermis to ZnO catheter extracts in artificial urine affects tissue viability compared with control samples, which was not observed in the case of ZnO NPs coating with SiO2 or C. We suggest that silica and carbon coatings confer some protection against zinc ions release, improving ZnO coating safety.

Guidewire replacement of valved tunneled-cuffed silicone catheters with power injectable polyurethane tunneled-cuffed catheters or with ports.

Silicone Cuffed Centrally Inserted Central venous catheters (CICCs) were a type of catheters that have been used for a long time especially in cancer patients. Recently, thanks to biomedic research progresses, polyurethane catheters have resulted in higher surgical performances compared to classical silicone ones. Indeed, the inferior calibers of these new catheters lead to an extremely faster infusion rate. The presence of a valve at the tip of the catheter could suggest an impossible replacement procedure over a Seldinger guidewire. The aim of this article is to explain our replacement technique over guidewire of silicone cuffed and valved tunneled CICCs with a power injectable polyurethane cuffed tunneled CICC. The casistic presented was evaluated at the Vascular Access Unit of ASST Spedali Civili in Brescia, Italy. The study involved 35 successful catheter replacement over guidewire, meanwhile cases where patients presented sepsis, exit site infection, or catheter damage were premeditatedly excluded. The maneuver was always conducted following the same procedure without noticing particular complications associated with CICC insertion. Indeed, the operation was quick, feasible, and safe. Septic, thromboembolic, or hemorrhagic complications also related to patients presenting dysfunctional coagulation cascade were not encountered. Our experience regarding the replacement technique of silicone cuffed and valved catheters over guidewire was considered feasible, accurate, and efficient for all patients treated, even in those presenting thrombocytopenia or a dysfunctional coagulation cascade.

Polymer-Coated Urinary Catheter Reduces Biofilm Formation and Biomineralization: A First-in-Man, Prospective Pilot Study

Purpose: Biofilm formation and biomineralization on urinary catheters may cause severe complications including infection and obstruction. Here, we describe an in vitro evaluation and prospective pilot clinical study of a silicone catheter coated with a biofilm-resistant polymer. Materials and Methods: Biofilm biomass and biomineralization on uncoated and coated catheters were quantified by confocal microscopy using fluorescently tagged bacteria or stained for biofilm and minerals. Biomineral identity was determined using scanning electron microscopy and X-ray spectroscopy. Biofilm formation and biomineralization were evaluated in vitro using uropathogens Proteus mirabilis and Pseudomonas aeruginosa and on catheters recovered from hospitalized patients. Fibrinogen in patient urine and on catheters was quantified using an immunofluorescence assay. Results: In vitro P. mirabilis and P. aeruginosa formed significantly less biofilm and biomineral and failed to block coated compared with uncoated catheters in a bladder model after 89 h. Biofilm-resistant polymer-coated catheters (n = 83) recovered from hospitalized patients exhibited significantly lower biofilm biomass and biomineralization compared with uncoated silicone catheters (n = 78). Electron microscopy with elemental analysis of recovered catheters revealed calcium oxalate crystals on coated compared with the struvite and apatite crystals on uncoated catheters associated with catheter blockage. Lower levels of biofilm-promoting fibrinogen in postcatheterization urine and on catheters from patients receiving coated catheters was observed compared with those receiving uncoated catheters indicative of a reduced inflammatory response. Conclusions: These data provide evidence that polymer-coated urinary catheters exhibit enhanced resistance to fibrinogen deposition, biofilm formation, and encrustation, reducing the risks associated with catheter-associated urinary tract infections and obstruction.

Attenuated inflammatory response in infant mice with Staphylococcus epidermidis CNS catheter infection

Children under one year of age are consistently found to be at the highest risk for shunt infection as a complication of hydrocephalus treatment, and repeated infections in the same patient are common. The mechanisms responsible for the increase in infant infection are not known. Our laboratory adapted our existing mouse model of Staphylococcus epidermidis central nervous system (CNS) catheter infection to characterize infection in infant mice as a foundation of on-going studies to determine the mechanisms of increased morbidity in infant shunt infections. The well-established model of S. epidermidis biofilm infection in the CNS was adapted to generate infection in 14-day old C57BL/6 mice. The catheter preparation was identical to the adult model, in which silicone catheters are pre-coated with a clinically derived biofilm-forming strain of S. epidermidis strain 1457) to introduce S. epidermidis into the brain. The catheters are stereotactically implanted into the lateral left ventricle. Bacterial titers as well as cytokine and chemokine levels were measured at days 1, 3, and 5 in mice implanted with sterile and S. epidermidis-coated catheters. Cultures demonstrated both catheter-associated and parenchymal infection through day 5 post-implantation. In contrast to prior adult models of CNS catheter infection, however, the catheter-associated bacterial burdens were less than or equal to parenchymal bacterial burdens. There was no significant difference between the chemokine and cytokine levels in the brain tissues of pups with sterile versus S. epidermidis infected catheters for any of the analytes tested. The infant model of S. epidermidis CNS catheter infection is characterized by both a greater degree of parenchymal spread of bacteria and the absence of the elevated pro-inflammatory cytokines previously observed in adult mice with this infection. The attenuated inflammatory response may contribute to the increased infection risk observed in this population.

Anti-infective Efficacy of Duloxetine against Catheter-Associated Urinary Tract Infections Caused by Gram-Positive Bacteria.

Catheter-associated urinary tract infections (CAUTIs) frequently occur following the insertion of catheters in hospitalized patients, often leading to severe clinical complications. These complications are exacerbated by biofilm-forming organisms such as Staphylococcus aureus, contributing to the emergence of multidrug-resistant (MDR) strains, which complicates treatment strategies. This study aims to investigate the antibacterial, antibiofilm, and antiadhesive properties of duloxetine against S. aureus in the context of CAUTI. Our findings demonstrate that duloxetine exhibits significant antibacterial activity, as evidenced by the agar diffusion method. A minimal inhibitory concentration (MIC) of 37.5 μg/mL was established using the microdilution method. Notably, duloxetine displayed inhibitory effects against biofilm formation on polystyrene surfaces up to its MIC level, as demonstrated by the crystal violet method. Intriguingly, the study also revealed that duloxetine could prevent biofilm formation at lower concentrations and reduce mature biofilms, as confirmed by scanning electron microscopy (SEM) and quantitative biofilm assays. Furthermore, duloxetine-coated silicone catheter tubes exhibited antibacterial properties against S. aureus in a bladder model, visualized by confocal laser scanning microscopy (CLSM) and corroborated through FDA and PI staining, highlighting noticeable morphological changes in S. aureus post-treatment. In conclusion, this study presents duloxetine as a promising alternative agent with antibacterial and antiadhesive properties against S. aureus in the prevention and management of CAUTI, warranting further exploration in the clinical setting.

Efficacy of Lysostaphin functionalized silicon catheter for the prevention of Staphylococcus aureus biofilm

Staphylococcus aureus readily forms biofilms on tissue and indwelling catheter surfaces. These biofilms are resistant to antibiotics. Consequently, effective prevention and treatment strategies against staphylococcal biofilms are actively being pursued over the past two decades. One of the proposed strategies involve the incorporation of antibiotics and antiseptics into catheters, however, a persistent concern regarding the possible emergence of antimicrobial resistance is associated with these medical devices. In this study, we developed two types of silicone catheters: one with Lysostaphin (Lst) adsorbed onto the surface, and the other with Lst functionalized on the surface. To confirm the presence of Lst protein on the catheter surface, we conducted FTIR–ATR and SEM-EDS analysis. Both catheters exhibited hemocompatibility, biocompatibility, and demonstrated antimicrobial and biofilm prevention activities against both methicillin-sensitive and resistant strains of S. aureus. Furthermore, the silicone catheters that were surface-functionalized with Lst showed substantially better and more persistent anti-biofilm effects when compared to the catheters where Lst was surface-adsorbed, both under in vitro static and flow conditions, as well as in vivo in BALB/c mice. These results indicate that surface-functionalized Lst catheters have the potential to serve as a promising new medical device for preventing S. aureus biofilm infections in humans.

A Novel Method of Spinal Accessory Nerve Banking Using Silicone Catheter for Functioning Free Muscle Transfer.

In secondary brachial plexus reconstruction, exploring an area that has already been operated on is challenging and time-consuming for a surgeon, especially in centers with a single-team approach. Due to their inertness and lack of adverse effects, silicone Foley catheters were used successfully during the reconstruction of flexor tendons. Based on the concept, we have achieved an acceptable functional outcome by banking the spinal accessory nerve in a silicon catheter for gracilis reanimation, which permits smooth dissection, maintains the length, and shortens the operating time for subsequent reconstruction. Level of Evidence: Level V.

Clinically Translatable Solid-State Dye for NIR-II Imaging of Medical Devices.

Medical devices are commonly implanted underneath the skin, but how to real-time noninvasively monitor their migration, integrity, and biodegradation in human body is still a formidable challenge. Here, the study demonstrates that benzyl violet 4B (BV-4B), a main component in the FDA-approved surgical suture, is found to produce fluorescence signal in the first near-infrared window (NIR-I, 700-900nm) in polar solutions, whereas BV-4B self-assembles into highly crystalline aggregates upon a formation of ultrasmall nanodots and can emit strong fluorescence in the second near-infrared window (NIR-II, 1000-1700nm) with a dramatic bathochromic shift in the absorption spectrum of ≈200nm. Intriguingly, BV-4B-involved suture knots underneath the skin can be facilely monitored during the whole degradation process in vivo, and the rupture of the customized BV-4B-coated silicone catheter is noninvasively diagnosed by NIR-II imaging. Furthermore, BV-4B suspended in embolization glue achieves hybrid fluorescence-guided surgery (hybrid FGS) for arteriovenous malformation. As a proof-of-concept study, the solid-state BV-4B is successfully used for NIR-II imaging of surgical sutures in operations of patients. Overall, as a clinically translatable solid-state dye, BV-4B can be applied for in vivo monitoring the fate of medical devices by NIR-II imaging.

Accidental rupture of membranes and neonatal infection after labor induction with silicone or latex balloon catheters: A retrospective cohort study

Objective(s)Accidental rupture of membranes (acROM), an insertion-related complication of the balloon catheter for labor induction, may prolong the duration of ruptured membranes. Prolonged rupture of membranes is associated with an increased risk of intra-uterine infection with possibly neonatal infection as result. Little is known about safety profiles of different catheters regarding the occurrence of these complications. This study compares the incidence of neonatal early-onset sepsis (EOS) and acROM in women receiving either silicone or latex balloon catheters. Study designA retrospective cohort study was performed including 2200 women (silicone balloon catheter, n = 1100 vs. latex balloon catheter, n = 1100). The primary outcomes were the incidence of acROM, and suspected and proven neonatal EOS. Secondary outcomes were: prolonged rupture of membranes, intrapartum fever, pre- or postnatal neonatal exposure to antibiotics, and perinatal outcomes. A subgroup analysis was performed between women with and without acROM. ResultsNo statistically significant difference with regard to suspected or proven EOS was seen between the silicone and latex groups. The acROM rate was significantly higher in the silicone group compared to the latex group (2.9 % and 0.3 %, p < 0.01). Prolonged rupture of membranes was significantly more common in the silicone group compared to the latex group (5.0 % and 2.4 %, p < 0.01), as was the use of intrapartum antibiotics (12.7 % and 9.6 %, p = 0.02). Neonates were significantly more often exposed to pre- or postnatal antibiotics in the silicone group compared to the latex group (17.6 % and 13.6 %, p = 0.01). Subgroup analysis showed significantly more suspected and proven neonatal EOS when catheter-insertion was complicated with acROM (11.4 % and 20.0 %), compared to cases without acROM (3.8 % and 2.5 %), irrespective of the type of catheter used. Conclusion(s)The use of silicone balloon catheters for labor induction results in higher rates of acROM, prolonged rupture of membranes and use of intrapartum antibiotics, compared to latex balloon catheters. No statistically significant differences were found in the occurrence of suspected or proven neonatal EOS, however neonates from the silicone group were more often exposed to pre- or postnatal antibiotics. When acROM occurs, irrespective of type of catheter used, suspected and proven neonatal EOS was seen more often.

Percutaneous Placement and Management of High-flow Catheter for Hemodialysis: The Case for DualCath, Two-tunneled, Single-lumen Silicone Catheters

Abstract Introduction: Tunneled central venous catheters (CVCs) are often regarded as the final choice for vascular access in patients needing extracorporeal renal replacement therapy due to their higher morbidity, lower performance, and increased cost. The inherent limitations of tunneled CVCs have been recognized and extensively analyzed in numerous studies. Materials and Methods: The objective is to offer a comprehensive technical note on the percutaneous placement and management of high-flow DualCath (DC) for hemodialysis, involving the simultaneous insertion of two tunneled single-lumen silicone catheters through a single skin incision and vein puncture. In addition, we aim to summarize the results derived from our extensive clinical experience. Results: This 20-year study involved the placement of 1035 DC devices. The main indications were end-stage kidney disease in 859 cases, acute kidney injury in 50 cases, and miscellaneous purposes in 30 cases. Most of the insertions were in the internal jugular vein, with varying dwell times averaging 213 ± 335 days. In total, the DC devices were used for 594 patient-years. Conclusion: DC can be placed using a minimally invasive percutaneous method in both chronic and acute settings, showcasing its exceptional versatility. The design and geometry of the two silicone cannulas are precisely tailored to meet the needs of clinicians, focusing on achieving optimal flow performance, and ensuring adequate dialysis.

Influence of RF Power on Wettability, Morphology and Bacterial Adhesion Properties of Oxygen Plasma Treated Silicone Catheter Surfaces

Influence of RF Power on Wettability, Morphology and Bacterial Adhesion Properties of Oxygen Plasma Treated Silicone Catheter Surfaces

Comparative Clinical Performances of Tunneled Central Venous Catheters versus Arterio-Venous Accesses in Patients Receiving High-Volume Hemodiafiltration: The Case for High-Flow DualCath, a Tunneled Two-Single-Lumen Silicone Catheter.

in this retrospective single-center study, we aimed to report on the clinical performances achieved with high-flow tunneled CVCs (DualCath or DCath) and compared them with arteriovenous accesses (AVAs, e.g., AV fistula, AV graft, and Thomas Shunt) in a hospital-based dialysis unit. Sixty-eight stage 5 chronic kidney disease dialysis-dependent patients (CKD5D) receiving high volume hemodiafiltration were followed-up with for 30 months. The study consisted of two phases: baseline cross-sectional and longitudinal follow-ups of key performance indicators. Clinical performances consisting of effective blood flow and blood volume, recirculation, urea and ionic Kt/V, total Kt, ultrafiltration volume, and percent reduction in β2-M were measured monthly as part of quality control in our unit. At baseline, the effective blood flow using a DCath was close to 400 mL/min, similar to an AVA. Recirculation with a DCath (7%, 6-13%) was higher than with an AVA. The diffusive dialysis dose delivered with a DCath (spKt and eKt/V) and convective dialysis dose achieved with a DCath were slightly lower than those achieved with AVAs, but they were still much higher than is recommended by guidelines. The percent reduction in β2-M achieved with a DCath was also 4 to 10% lower than that achieved with an AVA. On longitudinal follow-up, the main clinical performance indicators of DCaths (total Kt and total ultrafiltration volume, L/session) were maintained as very stable over time and close to those achieved with AVAs. As shown in this study, high-flow DualCath tunneled two-single-lumen silicone catheters may be used to deliver high volume hemodiafiltration in a reliable and consistent manner without compromising clinical performance. These results relied on the specific design of the two silicone cannulas and the strict adherence to best catheter practices.

Assessing the performance of concrete made with recycled latex gloves and silicone catheter using ultrasonic pulse velocity

Significant advances in concrete technology in modern times have prompted the search for environmentally friendly materials that could improve the properties of concrete. The inclusion of recyclable materials to conventional concrete can help in conserving key resources and produce environmentally friendly concrete. The incorporation of latex gloves and silicone catheter waste in concrete is one of the most important approaches to minimize the environmental problems associated with their disposal. In this study, an experiment was conducted to evaluate the effects of using latex gloves and silicone catheter waste as a substitute for coarse aggregates in concrete mixes. Concrete which was made with latex gloves and silicone catheter waste were subjected to UPV evaluations, i.e., ultrasonic pulse velocity tests at 28 curing days. Compressive strength and workability tests were also performed for reference and compared to the replacement sample. The inclusion of latex gloves and silicone catheter waste in proportions of 2.5%, 5%, 7.5 and 10% decreased the UPV values of the concrete. The results showed that the UPV values of the concrete decreased significantly from excellent to very good to poor for all specimens as the proportion of silicone catheters and latex gloves increased. The results showed that the addition of different proportions of latex gloves and silicone catheters decreased the compressive strength of the concrete by 86% and 59%, respectively, when the proportion of latex gloves and silicone catheters in the concrete mix was replaced by 10%. In addition, the fresh concrete property of concrete containing latex gloves and silicone catheters was decreased by 22% and 53%, respectively, when the proportion of latex gloves and silicone catheters was replaced by 10%. This study helps to raise environmental awareness by improving understanding of the waste generated and the importance of reusing waste as a substitute in concrete mixes.

Management of Hypospadias in Identical Twins at Mali Gavardo Hospital

This is a prospective study of two cases of hypospadias in identical twins with the same location and the same symptomatology at Mali Gavardo Hospital. Hypospadias corresponds to hypoplasia of the tissues forming the ventral surface of the penis responsible for an ectopic abruption of the urethra. Its aetiology is multifactorial, the surgical management is adapted according to the anatomical location.the Mathieu urethroplasty technique was used in both patients, urine drainage was performed with 8fr silicone catheter for 5 days. Post-operative follow-up was marked by a skin fistula in one case on the fourth day with spontaneous closure on day 8. Material Methodology: This was a prospective study of two cases of hypospadias in identical twins at the Mali Gavardo Hospital. The following parameters were studied: age, reasons for consultation, physical examination, complementary examinations, surgical treatment and post-operative follow-up. Conclusion: Hypospadias is a congenital malformation in males, the frequency of which is increasing throughout the world, and should be treated from an early age. In our context, the presence of the same anatomical form and the same location in both twins is still very rare in the literature, hence the need to share our experience with others. The Mathieu technique remains the reference technique for the management of hypospadias.

Hygiene management of intermittent self-catheterization using reusable silicone catheters in people with spinal cord lesions: A cross-sectional Internet survey in Japan.

To investigate hygiene management and catheter maintenance of reusable silicone catheters for intermittent self-catheterization (ISC) in Japan and examine their relationship with symptomatic urinary tract infection (sUTI). We conducted a cross-sectional Internet survey of people performing ISC using reusable silicone catheters owing to spinal cord lesions in Japan. Hygiene management and catheter maintenance of reusable silicone catheters and the incidence and frequency of sUTI were evaluated. We also examined the significant risk factors for sUTI. Of 136 respondents, 62 (46%), 41 (30%), and 58 (43%) washed hands with water, washed hands with soap, and cleaned or disinfected the urethral meatus every time or most of the time before ISC, respectively. No significant difference was observed in the incidence and frequency of sUTI between respondents who adhered to these procedures and those who did not. There were no significant differences in the incidence and frequency of sUTI in respondents who changed their catheters every month and in those who changed their preservation solution within 2 days compared with those who did not. In multivariate analysis, pain during ISC, inconvenience of indoor mobility, bowel management problems, and participants' feeling of never having received instruction on catheter replacement were significant risk factors for sUTI. There are individual differences in hygiene management and catheter maintenance of reusable silicone catheters, but the influence of these differences on the incidence and frequency of sUTI is not clear. Pain during ISC, bowel management problems, and inadequate instruction on catheter maintenance procedures are factors associated with sUTI.

ID: 207123 When to Evaluate for Catheter Revision/Replacement in Long-Term Intrathecal Baclofen Pump Users: A Case Series

Baclofen withdrawal is a life-threatening issue that has been demonstrated in patients with intrathecal baclofen use with catheter-related dysfunction. Prior to 2012, Medtronic baclofen pumps used traditional silicone catheters. In 2012, Medtronic introduced a new coated catheter designed to increase catheter strength and reduce kinking and occlusions. According to a 2016 review comparing traditional silicone catheters vs the coated catheter in children, 18% compared with 1.1% had catheter-related complications in the traditional and coated catheter groups respectively1. According to a 2020 Product Performance Report, there were 700 catheter-related events out of 5475 catheters (12.79%) and 277 events out of 2779 catheters (9.97%) in the old and new catheter models, respectively2.

Quantification of mechanical properties in long-term in vivo used silicone catheter lines according to DIN 10555-3

BackgroundTotally implantable central venous access port devices are crucial for intravenous application of chemotherapeutics and long-term therapy for chronic disease. Common complications include thrombosis and device fracture related to altered material properties through exposure in situ. This study exhibits whether uniaxial tensile properties (DIN 10555–3) of in vivo used catheters prove inferior to unused catheters. Material and methods5 unused, originally packed silicone catheters were cut into 6 segments of 50 mm: 3 segments each were cleaned via cleaning solution (n = 15) while 3 segments were left unattended (n = 15). Distal segments (50 mm) of long-term in vivo used silicone catheters were cleaned before testing (n = 33). Overall mechanical behavior was tested in a custom-made self-centering, torsion free carrier. Maximum force stress at failure, strain at failure and Young's modulus were determined and statistically analyzed. FindingsUnused catheters showed no significant difference in testing. in vivo used catheters exhibited 20% lower maximal force than unused catheters (p < 0.001), strain at break (p 〈0,001), and 7% higher elastic modulus (p = 0.004; power: 0.845). Due to a constant cross section area, stress at failure was proportional to maximum force (p < 0.001). Relation between determined parameters and dwell times was non-significant. InterpretationIn vivo long-term used silicone catheters showed significantly lower ultimate strength than unused ones. It is likely that in situ altering changes the mechanical properties of catheters and may potentially lead to failure.

Domestic LED bulb induced photodynamic effect of Toluidine Blue O-embedded silicone catheters against urinary tract infection

BackgroundNovel combination of Toluidine Blue O (TBO) embedded silicone catheter with domestic/household LED bulb has a potential in clinical infection such as prevention of multi drug resistant catheter-associated urinary tract infections (CAUTIs) through photodynamic therapy. Material and methodsPreliminarily, TBO was entrapped into silicone catheter by swell-encapsulation-shrink method. Further, in vitro study was carried out to check the antimicrobial photodynamic efficacy of TBO with domestic/household LED light. Antibiofilm activity was evaluated by scanning electron microscopy. ResultsThe results showed that these modified TBO embedded silicone catheters showed significant antimicrobial and antibiofilm activity against vancomycin resistant Staphylococcus aureus VRSA. Small piece (1 cm) of TBO-embedded silicone catheter (700 µM) showed 6 log10 reduction in the viable count when exposed for only 5 min of domestic/household LED bulb, while 1 cm piece of 500 µM and 700 µM concentration of TBO-embedded catheter eradicated all bacterial load when exposed to 15 min of light. Segment of medical grade TBO-embedded silicone catheters were used to carry out investigation of reactive oxygen species generation mainly singlet oxygen that contributes to type II phototoxicity. ConclusionThese modified catheter provides cost effective, easy to manage and less time consuming therapy to eliminate CAUTIs.

Enhancing microbiostatic properties of silicone catheters with Al2O3 coatings deposited by atomic layer deposition

Catheter-associated infections are a concern in healthcare and the leading cause of hospital-acquired infections, which can be caused by a variety of microorganisms, including bacteria and fungi. To prevent severe complications, developing materials with antimicrobial and/or microbiostatic properties is critical. Atomic layer deposition (ALD) is a thin-film deposition technique that precisely controls the thickness and composition of deposited metallic oxide films. ALD is promising for creating biomedical devices, drug delivery systems, and tissue engineering scaffolds with complex geometries. Given the microbiostatic properties of some metallic oxides-coatings, which act hampering the adherence of microorganisms, this work investigated the ALD of Al2O3 thin films on the surface and lumen of silicone catheters. Herein, we showed that Al2O3-coated silicone catheters with a thickness of 100 nm inhibited the formation of biofilm towards Staphylococcus aureus, Escherichia coli and Candida albicans, while reducing the contamination by 1 Log. The low temperature ALD approach presented in this investigation paves the way for further studies on active coatings aiming at biomedical devices with improved microbiostatic properties towards different microorganisms.

Dynamic analysis of small droplets at constant pressure and analytical model for drip systems and very low pressure drop-on-demand applications

We study the evolution of the growing volume of a droplet formed out of a capillary tube driven at a constant applied pressure by optical volume detection. A particular application aims at modeling the dynamic of the drop in the case of the injection of drugs in the middle-ear cavity using a small target drug delivery system. Various dispense tips such as a steel needle or silicone catheters and different t-BuOH aqueous solutions were used. A physical model based on the simplified Laplace–Young equation for a spherical droplet was developed to interpret the experimental results and model the observed deviation of the mean flow rate from the Poiseuille law when the drop radius is smaller than the capillary length. We emphasize the large influence of the surface tension which introduces a highly nonlinear effect at low applied pressure just above the capillary threshold pressure. The model fits well the evolution of the growing volume at various applied pressure up to a maximum diameter corresponding to the drop size close to the capillary length of the fluid, lc=γ/ρg, based on the liquid density ρ, gravity g and surface tension γ. We demonstrate that the model can also be applied to non spherical pendant droplets providing the apex elongation over the drop height of a spherical cap of the same volume is kept in a 30% range.