Surface modification of AISI 316 L stainless steel with polyvinyl alcohol/chitosan/sol-gel bioactive glass coating by electrospinning method

Abstract

AISI 316 L stainless steel has several applications in biomedical implants owing to its good corrosion resistance and mechanical properties. However, 316 L stainless steel alone may not provide sufficient biocompatibility. Hence, surface modifications such as biocompatible coatings are considered to improve the biocompatibility of implants. In this research, electrospinning composite solutions were prepared by blending a polymer solution of PVA/Chitosan (60:40 wt. %, respectively) non-calcined sol-gel-derived bioactive glass (BG-gel) at different volume percentages (Polymer solution/ BG sol: 100:0, 90:10, 85:15, 80:20) and named B0, B10, B15, and B20, respectively, and then coated on a polished AISI 316 L stainless steel substrate. The electrospinning of the samples was continued for 1 h with the following parameters: voltage = 25 kV, distance = 15 cm, and flow rate = 0.1 ml/h. The average diameter and distribution of nanofibers, chemical analysis, and wettability of the sample surface were characterized by FESEM, FTIR, and contact angle tests. In addition, bioactivity tests for all samples and viability tests of MG-63 osteoblast-like cells were performed for the B0 and B15 samples; also, cell attachment in these two samples was observed by FESEM images after 1 day of cultivation. Results indicate thinner and smoother fibers with an average fiber diameter of 157 nm for B0 and thicker fibers with at least a 120 nm increase in average fiber diameter in other samples in the presence of BG-sol. The contact angle evaluation of the samples shows contact angles of 21.0°, 21.4°, 17.0°, and 41.7° for B0, B10, B15, and B20, respectively. In addition, the bioactivity test revealed more hydroxyapatite nucleation upon the addition of more BG-sol to the composite solution. The cell viability results of the B0 and B15 samples show the same range of at least 93 % viability, which proves the low cytotoxicity and good biocompatibility of both samples. FESEM images of MG-63 cell attachment for B0 and B15 show good biocompatibility for both samples; especially for B15, which shows good spread and adhesion of multipolar stellate-shaped cells.