Abstract
ObjectiveVarious surface modification techniques that can further improve the function and usability of stainless steel as a medical device have been reported. In the present study, the physical and biological properties of nanoporous stainless steel as well as its usefulness for drug delivery were assessed.MethodsThe specimen was prepared with a circular disk shape (15 mm in diameter and 1 mm in thickness). The disk was subjected to electropolishing at a constant voltage of 20 V and 10 A for 10 min in an acidic environment (50% H2SO4). Everolimus (EVL) was used as a testing drug for drug-loading capacity of the material surface and release kinetics. The physiobiological properties of the material were assessed using platelet adhesion, and smooth muscle cell (SMC) adhesion, migration, and proliferation assays.ResultsThe surface roughness of the postpolishing group was greater than that of the nonpolishing group. Platelet adhesion and SMC adhesion and migration were inhibited in the postpolishing group compared to those in the prepolishing group. In the postpolishing group, the total amount of EVL on the surface (i.e., drug storage rate) was higher and the drug release rate was lower, with half the amount of the EVL released within 4 days compared with only 1 day for that of the prepolishing group.ConclusionTaken together, this stainless steel with a nanoporous surface could be used as a medical device for controlling cellular responses and carrying drugs.
Highlights
Various surface modification techniques that improve the function and usability of stainless steel as a medical device have been reported
The variation in the surfacemodified roughness was analyzed via atomic force microscopy (AFM) topography
The three-dimensional AFM images revealed that the roughness average (Ra) was increased (53.3%) in the postpolishing group compared with that in the prepolishing group (Ra: prepolishing 6.1 ± 1.02 nm; postpolishing 9.2 ± 1.74 nm, n = 5, p < 0.05; Fig. 3)
Summary
Various surface modification techniques that improve the function and usability of stainless steel as a medical device have been reported. The porous surface of stainless steel may improve biocompatibility [1], and provide an environment in which biological agents and drugs can be efficiently transported. These innovative methods help in creating specific surfaces that allow binding of the target drug onto the metal surface. Biophysical surface modification and optimization have gained immense interest in research of biomaterial sciences [2, 3]. Such surface modification methods have recently been used to improve the blood [4] and tissue compatibility of biomaterials [5]. Several studies have reported that the formation of nanopores on an implant surface
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