Surface Modification of Zn-Cu Alloy with Heparin Nanoparticles for Urinary Implant Applications.

In this work, an investigation on the Zn-Cu alloy coated with heparin was conducted in order to explore the potentiality of its application as a feasible alternative for biodegradable implants, with the specific goal of addressing the issue of encrustation in the urinary system. The stability of the nanoparticles were characterized by dynamic light scattering. Typical surface characterization such as X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy were used to demonstrate a successful immobilization of the NPs. The in vitro corrosion behavior was studied by potentiodynamic polarization and immersion tests in artificial urine (AU) at 37 °C. The 8 weeks in vivo degradation, encrustation resistance, hemocompatibility, and histocompatibility were investigated by means of implantation into the bladders of rats. Both in vitro and in vivo degradation tests exhibited a higher degradation rate for Zn-Cu and NPs groups when compared to pure Zn. Histological evaluations and hemocompatibility revealed that there was no tissue damage or pathological alterations caused by the degradation process. Furthermore, antiencrustation performance and urinalysis results confirmed that the modified alloy demonstrated significant encrustation inhibitory properties and bactericidal activity compared to the pure Zn control. Our findings highlight the potential of this modified alloy as an antiencrustation biodegradable ureteral stent.

In vivo study on heparin/poly-l-lysine-copper coating for surface functionalization of ureteral stent.

Polyurethane (PU) ureteral stents are used in clinics to maintain the ureteral patency. Due to biofilm formation and encrustation complications, long-term clinical usage has been limited. It is therefore necessary to develop an effective response to this unmet medical need. A heparin/poly-l-lysine/copper (NPs) coating was developed in our previous work that showed the effect of preventing infection and encrustation in vitro. In this work, a further study was conducted by grafting NPs on clinical ureteral stents that then were implanted into the infectious bladders of Wistar rats to investigate the effects of nanoparticles on bacterial growth and crystal deposition in vivo. It was found that decreased numbers of adherent microbes, urease amount splitting by bacteria, and deposited crystals were observed on the NPs stents with significant differences in comparison with PU stents. Besides, histological analysis showed that the NPs stents decreased the host tissue inflammation in close relation to the decrease biofilm formation and encrustation after 28 days of implantation.

In vitro and in vivo studies on bacteria and encrustation resistance of heparin/poly-L-lysine-Cu nanoparticles coating mediated by PDA for ureteral stent application.

Ureteral stents are commonly utilized as a medical device to aid the flow of urine. However, biofilm formation and encrustation complications have been clinical problems. To overcome this challenge, heparin/poly-L-lysine-copper (Hep/PLL-Cu) nanoparticle was immobilized on a dopamine-coated polyurethane surface (PU/NPs). The stability and structural properties of the nanoparticles were characterized by Zeta potential, poly dispersion index, transmission electron microscopy, atom force microscopy and contact angle. The surface composition, antibacterial potency, encrustation resistance rate and biocompatibility of PU/NPs were investigated by scanning electron microscope, X-ray photoelectron spectroscopy, antibacterial assay and MTS assay, respectively. In addition, the anti-encrustation property was studied by implanting coated NPs stents in the rat bladder for 7 days. It was shown that the size and distribution of Hep/PLL-Cu nanoparticles were uniform. PU/NPs could inhibit Proteus mirabilis proliferation and biofilm formation, and exhibit no cytotoxicity. Less encrustation (Ca and Mg salt) was deposited both in vitro and in vivo on samples, demonstrating that the NPs coating could be a potential surface modification method of ureteral material for clinical use.