Effect of Vaporized Hydrogen Peroxide and Nitrogen Dioxide Sterilization on Nitinol.

Background: Nitinol is used as the structural framework in numerous types of medical devices (e.g., guidewires, transcatheters, stents). The desire to understand the material compatibility of nitinol with vaporized hydrogen peroxide (VH2O2) and nitrogen dioxide (NO2) sterilization is increasing in healthcare technology. As a result of increased regulatory pressure and capacity limitations related to ethylene oxide (EO) sterilization, the industry is seeking alternative, sustainable sterilization options. Objective: This study sought to characterize the corrosion resistance of nitinol metal alloy wire when exposed to varying levels of VH2O2 and NO2 sterilization. Methods: Scanning electron microscopy (SEM) imaging and energy-dispersive X-ray spectroscopy (EDS) scans were performed to understand the effects of VH2O2 and NO2 sterilization treatments on the surface morphology and chemical composition of nitinol. Results: From the SEM-EDS results, no notable difference was observed when comparing VH2O2 and NO2 test samples with nonsterile control samples. In addition, cyclic potentiodynamic polarization measurements were performed per ASTM F2129-19a to determine corrosion susceptibility. No considerable changes were detected in the electrochemical potential after VH2O2 and NO2 sterilization treatments, when compared with the nonsterile control samples. Conclusion: SEM-EDS and corrosion test results indicated no considerable changes in the surface properties or electrochemical potential of the sterilized samples compared with the nonsterilized control samples. Therefore, nitinol metal showed promising results for compatibility with VH2O2 and NO2 sterilization.

A rapid-cycle assessment strategy for understanding the opioid overdose epidemic in local communities.

Background: Certain communities in the United States experience greater opioid-involved overdose mortality than others. Interventions to stem overdose benefit from contextual understandings of communities' needs and strengths in addressing the opioid crisis. This project aims to understand multiple stakeholder perspectives on the opioid epidemic in communities disproportionately affected by opioid-involved overdose mortality. Methods: We performed a rapid-cycle qualitative assessment study utilizing in-depth interviews with community stakeholders and observations of community meetings in eight communities in Allegheny County, Pennsylvania, USA, disproportionately impacted by opioid-involved overdose mortality. Stakeholder categories included: current and past illicit users of opioids; medical and social service providers; emergency medical services; law enforcement; spouse or other family members of illicit users/former users of opioids; government officials; school officials; community members. Content analysis was utilized to identify themes and answer study questions. Regular feedback to stakeholders was provided to support targeted interventions. Results: We performed semi-structured, in-depth interviews with 130 community stakeholders and 29 community meeting observations in 2018-2019. Participants perceived similar economic and social determinants as origins of the opioid overdose epidemic including lack of economic resources, loss of jobs, transient populations and dilapidated housing. However, they differed in their awareness of and attention to the epidemic. Awareness was dependent on the visibility of opioid use (presence of paraphernalia litter, location of drug users, media coverage, and relationship to users). Overall, there was good knowledge of naloxone for opioid overdose reversal but less knowledge about local syringe services programs. Perceptions of harm reduction efforts were ambivalent. Conclusions: Members of communities impacted by the opioid epidemic perceived that economic downturn was a major factor in the opioid overdose epidemic. However, the varied beliefs within and between communities suggest that interventions need to be tailored according to the cultural norms of place.

Surface modification of Ni-Ti alloys for stent application after magnetoelectropolishing.

The constant demand for new implant materials and the multidisciplinary design approaches for stent applications have expanded vastly over the past decade. The biocompatibility of these implant materials is a function of their surface characteristics such as morphology, surface chemistry, roughness, surface charge and wettability. These surface characteristics can directly influence the material's corrosion resistance and biological processes such as endothelialization. Surface morphology affects the thermodynamic stability of passivating oxides, which renders corrosion resistance to passivating alloys. Magnetoelectropolishing (MEP) is known to alter the morphology and composition of surface films, which assist in improving corrosion resistance of Nitinol alloys. This work aims at analyzing the surface characteristics of MEP Nitinol alloys by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The wettability of the alloys was determined by contact angle measurements and the mechanical properties were assessed by Nanoindentation. Improved mechanical properties were observed with the addition of alloying elements. Cyclic potentiodynamic polarization tests were performed to determine the corrosion susceptibility. Further, the alloys were tested for their cytotoxicity and cellular growth with endothelial cells. Improved corrosion resistance and cellular viability were observed with MEP surface treated alloys.

A Comparative Biocompatibility Analysis of Ternary Nitinol Alloys.

Nitinol alloys are rapidly being utilized as the material of choice in a variety of applications in the medical industry. It has been used for self-expanding stents, graft support systems, and various other devices for minimally invasive interventional and endoscopic procedures. However, the biocompatibility of this alloy remains a concern to many practitioners in the industry due to nickel sensitivity experienced by many patients. In recent times, several new Nitinol alloys have been introduced with the addition of a ternary element. Nevertheless, there is still a dearth of information concerning the biocompatibility and corrosion resistance of these alloys. This study compared the biocompatibility of two ternary Nitinol alloys prepared by powder metallurgy (PM) and arc melting (AM) and critically assessed the influence of the ternary element. ASTM F 2129-08 cyclic polarization in vitro corrosion tests were conducted to evaluate the corrosion resistance in phosphate buffered saline (PBS). The growth of endothelial cells on NiTi was examined using optical microscopy.