Evaluation of cellular response and drug delivery efficacy of nanoporous stainless steel material

Abstract

Objective Various 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. Methods The 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. Results The 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. Conclusion Taken together, this stainless steel with a nanoporous surface could be used as a medical device for controlling cellular responses and carrying drugs.

Nanoporous Stainless Steel Materials for Body Implants—Review of Synthesizing Procedures

“…The diameter of the nanopores is usually in a range between, say, 10 and a few 100 nm. Such a surface finish was reported by authors who used electrolytes free from organic chemicals [ 43 , 44 , 45 ].…”

“…Bae et al [ 43 ] synthesised nanoporous 316L stainless steel surfaces to study the platelet adhesion, cellular response and drug delivery capability of such materials. Unlike previously cited authors, Bae et al [ 43 ] used an electrolyte composed of 1 M H 2 SO 4 and 1.0 wt.% hydrofluoric acid solution with pH 2–3. A stainless steel substrate was the anode, and the cathode was a platinum plate.…”

“…The surface morphology of nanoporous stainless steel enabled a small increase in the drug amount, but the release rate dropped significantly as compared to the untreated samples. About 75% of the drug was released on the first day in the case of an untreated sample, but the samples prepared according to the methods developed by Bae et al [ 43 ] enabled much slower release, i.e., 18% till the end of the first day, 40% till day 4 and 62% after a week. The surface finish with dense pores enabled gradual drug release, which was measurable even a month after deposition.…”

“…The most frequently used organic component was ethylene glycol. For instance, Tsutchiya et al [ 27 ] were able to prepare ordered pore arrays in ethylene glycol-, di-ethylene glycol- and poly-ethylene glycol-based electrolytes, while Bae et al [ 43 ] reported on the formation of nanoporous structures without ordered morphology by using inorganic electrolyte. The formation of highly oriented structures is only reported for a limited range of processing parameters, which include the concentration of other chemicals in the electrolyte, the electrolyte temperature, the anodisation voltage and the corresponding current density, the treatment time, and perhaps some peculiarities which are not revealed in the literature.…”

Recent Advancements in the Fabrication of Functional Nanoporous Materials and Their Biomedical Applications

“…These materials have shown to act as excellent reservoirs for drugs and biomolecules due to their ability to minimize loss, biocompatibility, and their inherent physical and chemical properties [ 9 ]. Similarly, Bae et al showed that stainless steel fabricated with nanoporous surface for orthopedic implants and stents demonstrated enhanced capabilities to store drugs and maximize its efficacy [ 140 ]. Furthermore, it has been shown that the nanoporous materials possess high surface area, tunable pore sizes, and have the capabilities to demonstrate controlled release of drugs and pesticides enabling these materials to be used in the pharmaceutical and agriculture industries [ 141 ].…”