Spray coating of foley urinary catheter by chlorhexidine-loadedpoly(ε-caprolactone) nanospheres: effect of lyoprotectants, characteristics, and antibacterial activity evaluation

A comprehensive status update on modification of foley catheter to combat catheter-associated urinary tract infections and microbial biofilms

Present-day healthcare employs several types of invasive devices, including urinary catheters, to improve medical wellness, the clinical outcome of disease, and the quality of patient life. Among urinary catheters, the Foley catheter is most commonly used in patients for bladder drainage and collection of urine. Although such devices are very useful for patients who cannot empty their bladder for various reasons, they also expose patients to catheter-associated urinary tract infections (CAUTIs). Catheter provides an ideal surface for bacterial colonization and biofilm formation, resulting in persistent bacterial infection and severe complications. Hence, rigorous efforts have been made to develop catheters that harbour antimicrobial and anti-fouling properties to resist colonization by bacterial pathogens. In this regard, catheter modification by surface functionalization, impregnation, blending, or coating with antibiotics, bioactive compounds, and nanoformulations have proved to be effective in controlling biofilm formation. This review attempts to illustrate the complications associated with indwelling Foley catheters, primarily focussing on challenges in fighting CAUTI, catheter colonization, and biofilm formation. In this review, we also collate scientific literature on catheter modification using antibiotics, plant bioactive components, bacteriophages, nanoparticles, and studies demonstrating their efficacy through in vitro and in vivo testing.

Encapsulation of Cyclosporine A-Loaded PLGA Nanospheres in Alginate Microbeads for Anti-Inflammatory Application

The controlled release of cyclosporine A (CsA) microencapsulated in alginate microbeads is a novel drug delivery system for the treatment of inflammatory diseases. In this study, CsA-loaded nanospheres encapsulated in alginate microbeads were applied to evaluate their controlled release profile and anti-inflammatory activity. Initially, a controlled-release drug delivery system was created by encapsulating CsA-loaded PLGA nanospheres within alginate microbeads. CsA-loaded PLGA nanospheres had a diameter of 418.70 ± 59.08 nm, a zeta potential of -22 ± 0.57 mV, and a polydispersity index of 0.517 ± 0.010. CsA-loaded nanosphere-encapsulated alginate microbeads were stable for 37 days. After encapsulating CsA-loaded PLGA nanospheres in the alginate microbeads, 5.60% of CsA was released after 24 h, and approximately 85.90% of the drugs were diffused until day 64. The cytotoxic and anti-inflammatory properties of the CsA released from the microbeads were evaluated in vitro using a murine macrophage cell line (RAW 264.7 cells). CsA-loaded nanosphere-encapsulated alginate microbeads inhibited 39.47 ± 1.71% of nitric oxide production from the RAW 264.7 cells on day 3, whereas nanosphere-encapsulated alginate microbeads inhibited 18.45 ± 1.56% only. CsA released from CsA-loaded nanosphere-encapsulated alginate microbeads had a RAW cell viability of 82.73 ± 5.58% on day 3 compared to 87.59 ± 0.69% of nanosphere-encapsulated alginate microbeads. The efficacy of the CsA-loaded nanosphere-encapsulated alginate microbeads in protecting the immune system via a controlled drug delivery system was established through anti-inflammatory and cell viability evaluation. Based on this research, the controlled release of CsA-loaded nanosphere-encapsulated alginate microbeads provides an innovative treatment for inflammatory diseases.

Nanotherapeutics for the delivery of antifungal drugs

The treatment of fungal infections is challenging with high death rates reported among immunocompromised patients. The currently available antifungals suffer from poor bioavailability and solubility, pharmacokinetics, and drug resistance, with limited cellular uptake. The clinical pipeline of new antifungals is dry. The incorporation of antifungal drugs into polymer-based nanocarriers to form nanotherapeutics is a promising approach to enhance the therapeutic outcomes of the available antifungal drugs. This review summarizes different polymer-based nanotherapeutics strategies that have been explored for the delivery of antifungals, resulting in enhanced therapeutic outcomes, such as improved pharmacokinetics, targeted/sustained delivery, prolonged drug circulation, retention of the drugs at the localized site of action, and overcoming drug resistance when compared with the free antifungal drugs.

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.

Dual-sized hollow particle incorporated fibroin thermal insulating coatings on catheter for cerebral therapeutic hypothermia

Selective endovascular hypothermia has been used to provide cooling-induced cerebral neuroprotection, but current catheters do not support thermally-insulated transfer of cold infusate, which results in an increased exit temperature, causes hemodilution, and limits its cooling efficiency. Herein, air-sprayed fibroin/silica-based coatings combined with chemical vapor deposited parylene-C capping film was prepared on catheter. This coating features in dual-sized-hollow-microparticle incorporated structures with low thermal conductivity. The infusate exit temperature is tunable by adjusting the coating thickness and infusion rate. No peeling or cracking was observed on the coatings under bending and rotational scenarios in the vascular models. Its efficiency was verified in a swine model, and the outlet temperature of coated catheter (75 μm thickness) was 1.8-2.0 °C lower than that of the uncoated one. This pioneering work on catheter thermal insulation coatings may facilitate the clinical translation of selective endovascular hypothermia for neuroprotection in patients with acute ischemic stroke.

Antibiotic impregnation and nanocoating of external ventricular drainage catheters for antibacterial applications: Evaluation of in vitro studies and molecular docking

The most suitable method to treat hydrocephalus disease is to insert a shunt catheter that drains the cerebral spinal fluid (CSF); however, shunt implantation is often associated with various bacterial infections. In this study, antibiotic-loaded nanospheres were prepared using the solvent evaporation technique and coated on an antibiotic-impregnated shunt surface to promote shunt antibacterial properties. Clindamycin (CDM) and rifampicin (RIF) were in combination loaded in a single nanosphere, whereas trimethoprim (TMP) was loaded individually in triblock copolymers [(d,l-lactide-random-ε-caprolactone)-block-poly(ethylene glycol)-block-(d,l-lactide-random-ε-caprolactone)] (PLEC). The drug-loading content, encapsulation efficiency, yield, size, and zeta potential of the antibiotic-loaded nanospheres were measured. The results showed that the drug-loading content of clindamycin- and rifampicin-loaded nanospheres (CDM/RIF-NPs) was approximately 3% and 8%, respectively, at a drug to polymer ratio of 1:2. In addition, trimethoprim-loaded nanospheres (TMP-NPs) showed nearly 7% drug loading at equal drug and polymer ratios. The amount of drug release was determined before and after the coating of nanospheres on the shunt surface. In addition, in silico molecular docking studies indicated the good chemical interaction of these antibiotics with PLEC, and the results were consistent with those of impregnation studies. Antibacterial tests of coated external ventricular drainage showed antibacterial activity for up to 21 days.

Overview of Antimicrobial Biodegradable Polyester-Based Formulations

As the clinical complications induced by microbial infections are known to have life-threatening side effects, conventional anti-infective therapy is necessary, but not sufficient to overcome these issues. Some of their limitations are connected to drug-related inefficiency or resistance and pathogen-related adaptive modifications. Therefore, there is an urgent need for advanced antimicrobials and antimicrobial devices. A challenging, yet successful route has been the development of new biostatic or biocide agents and biomaterials by considering the indisputable advantages of biopolymers. Polymers are attractive materials due to their physical and chemical properties, such as compositional and structural versatility, tunable reactivity, solubility and degradability, and mechanical and chemical tunability, together with their intrinsic biocompatibility and bioactivity, thus enabling the fabrication of effective pharmacologically active antimicrobial formulations. Besides representing protective or potentiating carriers for conventional drugs, biopolymers possess an impressive ability for conjugation or functionalization. These aspects are key for avoiding malicious side effects or providing targeted and triggered drug delivery (specific and selective cellular targeting), and generally to define their pharmacological efficacy. Moreover, biopolymers can be processed in different forms (particles, fibers, films, membranes, or scaffolds), which prove excellent candidates for modern anti-infective applications. This review contains an overview of antimicrobial polyester-based formulations, centered around the effect of the dimensionality over the properties of the material and the effect of the production route or post-processing actions.

Fabrication and in vitro characterization of zinc oxide nanoparticles and hyaluronic acid-containing carboxymethylcellulose gel for wound healing application

Chronic wounds, such as burns and diabetic ulcers, are complex wounds sustained by the skin that require life-long rehabilitation and have the potential to deteriorate and get infected. The number of patients with this ailment has been steadily increasing. This illness demands the use of new dressings with the best capabilities for managing wound healing. This study created an gel with carboxymethylcellulose (CMC), hyaluronic acid (HA), and zinc oxide nanoparticles (ZnO NPs). According to the findings, the manufacturing technique with a 1:4 ratio of HA and CMC gel had the best viscosity. Additionally, varying concentrations of zinc oxide nanoparticles (ZnO NPs) were added to the formula. Variations included 0.05, 0.125, 0.5, 1.0, 3.0, 5.0, and 10% by weight. In order to find the ideal dose and formulation, physical properties, an anti-bacterial test, and a cell migration assay were carried out. The samples with concentration of 0.5, 1.0, 3.0, 5.0 and 10% w/v showed ability to kill gram-positive and gram-negative bacteria. Wound healing experiments showed that cells proliferated for HA/CMC/ZnO gel with a weight-to-volume ratio of 0.05% and 1.0% w/v. In conclusion, according to all (physical and biological) characterization, the HA/CMC/ZnO gel with a weight-to-volume ratio of 1.0% w/v was found to have a considerable standard for wound-healing materials, demonstrating a promising effect against bacteria.

Nanomaterials in the Management of Gram-Negative Bacterial Infections

The exploration of multiplexed bacterial virulence factors is a major problem in the early stages of Escherichia coli infection therapy. Traditional methods for detecting Escherichia coli (E. coli), such as serological experiments, immunoassays, polymerase chain reaction, and isothermal microcalorimetry have some drawbacks. As a result, detecting E. coli in a timely, cost-effective, and sensitive manner is critical for various areas of human safety and health. Intelligent devices based on nanotechnology are paving the way for fast and early detection of E. coli at the point of care. Due to their specific optical, magnetic, and electrical capabilities, nanostructures can play an important role in bacterial sensors. Another one of the applications involved use of nanomaterials in fighting microbial infections, including E. coli mediated infections. Various types of nanomaterials, either used directly as an antibacterial agent such as metallic nanoparticles (NPs) (silver, gold, zinc, etc.), or as a nanocarrier to deliver and target the antibiotic to the E. coli and its infected area. Among different types, polymeric NPs, lipidic nanocarriers, metallic nanocarriers, nanomicelles, nanoemulsion/ nanosuspension, dendrimers, graphene, etc. proved to be effective vehicles to deliver the drug in a controlled fashion at the targeted site with lower off-site drug leakage and side effects.

Indwelling urinary catheter assembled with lidocaine-loaded polymeric strand for local sustained alleviation of bladder discomfort

Indwelling urinary catheters (IUCs) are used in clinical settings to assist detrusor contraction in hospitalized patients. However, an inserted IUC often causes catheter-related bladder discomfort. To resolve this, we propose an IUC coupled with local, sustained release of an anesthetic drug, lidocaine. For this, a thin strand composed of poly (lactic-co-glycolic acid) and lidocaine was separately prepared as a drug delivery carrier, which was then wound around the surface of the IUC to produce the drug-delivery IUC. Our results revealed that the drug-delivery IUC could exert the pain-relief effects for up to 7 days when placed in the bladder of living rats. Cystometrogram tests indicated that the drug-delivery IUC could significantly relieve bladder discomfort compared with the IUC without lidocaine. Furthermore, the expression of pain-related inflammatory markers, such as nerve growth factor, cyclooxygenase-2, and interleukin-6 in the biopsied bladder tissues was significantly lower when the drug-delivery IUC was used. Therefore, we conclude that an IUC simply assembled with a drug-loaded polymer strand can continuously release lidocaine to allow for the relief of bladder discomfort during the period of IUC insertion.

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.

In vivo catheterization study of chlorhexidine-loaded nanoparticle coated Foley urinary catheters in male New Zealand white rabbits

Foley urinary catheters were coated with chlorhexidine-loaded nanoparticles (CHX-NPs), encapsulated in the form of micelles and nanospheres. Both of nanoparticles were deposited by multilayer nanocoating through dip and spray coating on the catheter surface both inner and outer surface. In our previous studies, the nanocoating of Foley urinary catheters was studied for chlorhexidine release, degradation, antibacterial evaluation, cytotoxicity assessment, hemocompatibility, skin irritation, skin sensitization, and stability during storage. The results demonstrated the antimicrobial functions and biocompatibility of the coated catheters. In this study, coated urinary catheters were inserted in the bladders of rabbits for 7 day to investigate their efficacy. Histopathology results showed no inflammation, redness, or swelling on bladder and urethra tissues. Surface morphology comparison of uncoated catheters in the control group and coated catheters in the treatment group revealed more encrustation and crystallization on uncoated catheter than on coated catheter, indicating that catheters coated with CHX-NPs showed efficacy in delaying encrustation and bacterial colonization. These findings suggest that nanocoating of urinary catheters can potentially enhance the biocompatibility of medical devices.

Polymeric Nanoparticles for Antimicrobial Therapies: An Up-To-Date Overview

Despite the many advancements in the pharmaceutical and medical fields and the development of numerous antimicrobial drugs aimed to suppress and destroy pathogenic microorganisms, infectious diseases still represent a major health threat affecting millions of lives daily. In addition to the limitations of antimicrobial drugs associated with low transportation rate, water solubility, oral bioavailability and stability, inefficient drug targeting, considerable toxicity, and limited patient compliance, the major cause for their inefficiency is the antimicrobial resistance of microorganisms. In this context, the risk of a pre-antibiotic era is a real possibility. For this reason, the research focus has shifted toward the discovery and development of novel and alternative antimicrobial agents that could overcome the challenges associated with conventional drugs. Nanotechnology is a possible alternative, as there is significant evidence of the broad-spectrum antimicrobial activity of nanomaterials and nanoparticles in particular. Moreover, owing to their considerable advantages regarding their efficient cargo dissolving, entrapment, encapsulation, or surface attachment, the possibility of forming antimicrobial groups for specific targeting and destruction, biocompatibility and biodegradability, low toxicity, and synergistic therapy, polymeric nanoparticles have received considerable attention as potential antimicrobial drug delivery agents. In this context, the aim of this paper is to provide an up-to-date overview of the most recent studies investigating polymeric nanoparticles designed for antimicrobial therapies, describing both their targeting strategies and their effects.

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.