The new-generation coronary stents are expected to be biodegradable, and then the biocompatibility along with biodegradation becomes more challenging. It is a critical issue to choose appropriate biomimetic conditions to evaluate biocompatibility. Compared with other candidates for biodegradable stents, iron-based materials are of high mechanical strength, yet have raised more concerns about biodegradability and biocompatibility. Herein, a metal-polymer composite strategy is applied to accelerate the degradation of iron-based stents in vitro and in a porcine model. Furthermore, it is found that serum, the main environment of vascular stents, ensured the safety of iron corrosion through its antioxidants. This work highlights the importance of serum, particularly albumin, for an in vitro condition mimicking blood-related physiological condition, when reactive oxygen species, inflammatory response, and neointimal hyperplasia are concerned. The resultant metal-polymer composite stent is implanted into a patient in clinical research via interventional treatment, and the follow-up confirms its safety, efficacy, and appropriate biodegradability.
For potential applications in the isolation and enrichment of circulating tumor cells (CTCs), we have developed gold nanoparticle layers (GNPLs) of different roughness modified with TD05 aptamers (GNPL-APT). In serum-free binary cell mixtures containing Ramos cancer cells and CEM cells, the density of Ramos cells adherent to highly rough GNPL-APT was 19 times that of CEM cells. However, in serum-containing conditions, the specificity of GNPL-APT for Ramos cells was much reduced. To improve Ramos specificity in the presence of serum, we attached the TD05 aptamer to the layers via poly(oligo(ethylene glycol) methacrylate) (POEGMA) as an antifouling spacer (GNPL-POEGMA-APT). In serum-containing environment GNPL-POEGMA-APT showed an enhanced selectivity for Ramos cells, which increased with increasing surface roughness. The results of this study indicate that surfaces combining appropriate chemical composition and micro/nano roughness structures may be useful for cell separation, including the isolation of cancer cells for diagnosis.
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