Investigation of pattern transfer from Direct Laser Interference Patterned steel surfaces to Poly-L-Lactic Acid films

Abstract

Periodic surfaces have been shown to promote stent cell migration and proliferation and avoid platelet adhesion. Surfaces patterned with direct laser interference patterning (DLIP) have been investigated for many metallic materials, with promising results and new possibilities. To bring surface structuring benefits to new technologies like bioresorbable stents, cost-effective large-scale manufacturing is essential for increased affordability and accessibility. Bioresorbable stents, such as PLLA stents, can be made with additive manufacturing on a rotating steel rod. This is a cost-effective, reliable, and quick manufacturing technique, in which drugs can be embedded in its matrix. Printing PLLA on a modified surface can be sufficient for the material to shape its inner surface to the desired pattern. The feasibility of such a process was addressed, as well as problems like oxide transfer from the steel onto the PLLA, PLLA formability and final resulting surface. To do so, steel samples were modified via DLIP, an existing technique for PLLA stamping was adapted, and results were characterized via laser confocal microscopy, scanning electron microscopy, contact angle and raman spectroscopy. Results have shown that pattern transfer is possible, but oxide transfer occurs and modifications on methodology are needed to avoid it. Different patterns were characterized and had different transferability behaviors, but the overall analysis also revealed consistent patterns in terms of height, which could promote uniform endothelialization on the stent and, consequently, an improvement in overall bioresorbable stents efficacy and safety.

Outgoing