Coatings for Urinary Stents: Current State and Future Directions

Abstract

Urinary stent coatings are a strategy to tackle certain complications associated with the use of biomaterials. The latest innovations in surface coatings focused on the prevention of those problems, thus reducing further costs with treatments. Urinary stents associated symptoms, infections and encrustation are considered the major challenges, and, in an attempt to prevent such morbidity, several strategies were developed. Hence, coatings have been designed to improve quality of life for patients, reducing the friction, inhibiting uropathogens survival or attachment on stents, and avoiding the deposition of urinary crystals that triggers encrustation. Currently for ureteral stents, hydrophilic and diamond-like carbon coatings are commercial options associated with an enhanced performance of devices, comparing with uncoated ones. These commercially available approaches are all anti-adhesive coatings, and, in the general overview, this type of strategy appears to be a superior alternative than bactericidal coatings. Designs that trigger uropathogen death are usually associated with higher toxicity, and, in some cases, it can even favor the development of microbial resistance, which can hamper the infection treatment. With the present knowledge about antimicrobial mechanisms and inspired by nature, more cutting-edge alternatives, able to confer antimicrobial properties to the inner and outer parts of stents, will surely appear.

Medical Device-Associated Biofilm Infections and Multidrug-Resistant Pathogens

“…Surface modification Cellobiose deshydrogenase (CDH) CDH was covalently grafted onto plasma-activated urinary polydimethylsiloxane (PDMS) catheter surfaces. S. aureus [433] Metals or composite nanoparticles represent suitable alternatives for CA-UTI prevention and biofilm-related infections [434]. Several studies [409,[435][436][437][438][439] have reported that UCs coated with thin-films of silver alloy could reduce bacterial adhesion but also the incidence of asymptomatic bacteriuria and CA-UTI.…”

“…Other antibiotics such as gentamicin [453], chlorhexidine [454], ciprofloxacin [455], norfloxacin [456], triclosan [457], and sparfloxacin [418] have been tested as a coating agent. Although giving promising results, the antibiotic-based approach favors the apparition of bacterial resistance for long-term catheters (e.g., triclosan), leading to more serious infections [434,458].…”

“…Antifouling approaches can also prevent bacterial adhesion on UCs and biofilm formation by repelling them without harming them [377]. The principle of these strategies is the acquisition of anti-adhesive properties by physicochemical modifications of catheter surfaces in order to prevent bacterial adhesion in addition to a good antibacterial activity and low toxicity [376,434]. Moreover, this approach provides the advantage of low risk of drug resistance emergence [474].…”

“…Moreover, this approach provides the advantage of low risk of drug resistance emergence [474]. Additionally, the hydration layer increases patient com-fort due to low friction during UC placement [434]. There are wide antifouling approaches, especially hydrogels which are the most popular due to their hydrophilic structure which reduces bacterial growth [475].…”

“…These polymers repel foulants due to the formation of a hydration layer on the surface [449]. Among the hydrophilic coatings, some of them have been already commercialized including HydroPlus™ from Boston Scientific, AQ ® from Cook Urological, heparin-based coating Endo-Sof™ Radiance™ from Cook Urological, and SL-6 from Applied Medical [434].…”