Impact of Surface Functionalization by Nanostructured Silver Thin Films on Thermoplastic Central Venous Catheters: Mechanical, Microscopical and Thermal Analyses

Abstract: In this work, an interdisciplinary approach was employed to investigate the impact on thermoplastic catheters from the deposition of a thin (180 nm), metallic silver film by a pulsed ablation technique. Our characterization firstly involved tensile and bending tests, each one accompanied by finite element modeling aiming to elucidate the contributions resulting from bulk and coating to the device’s mechanical behavior. The morphological assessment of the surface before and after the deposition was performed by atomic force microscopy, specifically implemented to visualize the nanostructured character of the film surface and the extent to which the polymer was modified by the deposition process, focusing on coating delamination due to tensile stress. Finally, thermogravimetric–differential thermal analysis was carried out to evaluate whether silver deposition has affected the physiochemical structure of the polymer matrix. Our results establish that the deposition does not significantly alter the physical and chemical properties of the device. The presented characterization sets a useful precedent for elucidating how structural properties of polymeric materials may change after coating by electronic ablation techniques, highlighting the importance of employing a comprehensive approach for clarifying the effects of additive manufacturing on medical devices.

Keywords: central venous catheter; medical device; pulsed electron deposition; nanostructured coating; mechanical testing; finite element modeling; atomic force microscopy; TG-DTA

Bending tests were performed on a multiaxial mechanical tester (Mach-1 v500css, Biomomentum, Laval, QC, Canada) aiming to quantitative reproduce ASTM B571 Standard, which suggests to evaluate the adhesion of metallic coating after bending the device [32]. Specifically, bending was implemented in a “three-point” configuration, where supporting and loading aluminium pins had a diameter of four times the thickness of the CVC, i.e., 17.2 mm.