A novel chitosan and polydopamine interlinked bioactive coating for metallic biomaterials.

Chitosan coatings have shown good bioactive properties such as antibacterial and antiplatelet properties, especially on blood-contacted biomedical materials. However, as blood-contacted biomedical device, the intravascular metal stent has a burden with adverse effects on the structural integrity, such as mechanical load during implantation and substrate degradation if a biodegradable metal is used as the substrate. It is unquestionably true that the structural integrity of the coated stent is essential. The adhesion strength between the coating and the substrate positively affects it. Silane and polydopamine (PDA) interstitial layers have been investigated to improve the corrosion resistance, biosafety and adhesion strength. This work addressed this challenge by using PDA as an intermediate and glutaraldehyde as a linking agent to establish a strong link between the polymer coating and the intermediate coating. Compared with PDA-only and glutaraldehyde-linked silane layer, the novel coating displayed a notable increase in adhesion. When compared with the bare Ni-free stainless steel, the performance of the novel coating was not significantly different. This novel chitosan film on the glutaraldehyde linked-PDA interface can be applied to various metallic substrates where synergic bioactive and anticorrosive effects of PDA interstitial coating and chitosan are needed. Graphical abstract.

Study of drug-eluting coating on metal coronary stent.

Drug-eluting stent has been proved to decrease the restenosis caused by the stent implantation, owing to the existence of a drug-eluting coating on the stent. For ensuring the effectivity and security of the drug-eluting stent during the service period, the uniform surface, good deformation and stabilized drug release behavior of the stents should be satisfied. In this study, the performances mentioned were studied on stainless steel stents. The results showed that the surface morphology of the coating was affected by the sorts of solvent, the parameters of the spraying process and the addition of the plasticizer. The drug-eluting profile of the coating was influenced by the plasticizer content and PLGA/drug ratio of the coating. Meanwhile, the plasticizer as an additional agent obviously increased the deformation performance of the coating. Optimized parameters for preparation of the drug-eluting coating were investigated to obtain a drug-eluting coating with good integrated performances.

Design and fabrication of the nickel-free stainless steel coronary stent / 中国医疗器械杂志

A kind of coronary stent was made from Nickel-free stainless steel, and the technological process of the stent was studied. A preferable flexible and support force stent was simulated by a commercial finite element code ANSYS with laser cutting, pickling and vacuum annealing. This kind of coronary stent has more superiority. It was also presented that a self designed automatic stent electro-polishing device, which greatly improve efficiency and quality, and the optimization electro-polishing process was put forward.

Sensitization test of magnalium at the maximal dosage / 中国组织工程研究

BACKGROUND: Magnalium which is potential to be the medical biodegraded metal implant is more and more interesting,but it must be well biocompatibility to human body.OBJECTIVE: To evaluate the sensitization of magnalium (AZ31B).METHODS: A total of 35 guinea pigs were randomly divided into saline group (negative control group,n=10),5% volume of formaldehyde (positive control group,n=10),and AZ31B group (n=15).Sensitization test at the maximal dosage was performed according to "Biological evaluation of medical devices-Part 10: Tests for irritation and delayed-type hypersensitivity",including intracutaneous induction,local induction,and provocation.Patch was removed after 6,24,48,and 72 hours,and the skin response was classified accordingto Magnusson and Kligman criteria.Patch was removed after 72 hours,and skin was performed with biopsy,stained with FIE staining,and observed under optic microscope.RESULTS AND CONCLUSION: Sensitization response was not tested in both negative control group and AZ31B group at 24,48,and 72 hours after patch removal; however,moderate erythema was observed in the positive control group.Optic microscope demonstrated that criteria of allergy such as spongiosis,edema,and diffuse as well as perivascular mononuclear infiltration was not observed in the AZ31B group,but a few basophilic calls ware observed.This suggested that AZ31B was biologically safe for sensitization.

Anti-restenosis study on a new drug eluting stent / 生物医学工程学杂志

The objective of this experimental study was to assess the effects of a new kind of drug eluting coronary stent. Fourteen mini-pigs were used; seven normal stainless stents and seven new drug eluting stents were implanted in their normal coronary arteries, respectively. Angiography was performed and followed by pressure-fixation of the coronary arteries for light and electron microscopic examinations at the end of three months after implantation. Repeated angiography showed that all the stented coronary segments were open. With no additional antithrombotic treatment, there was no thrombus formed in the stented coronary segments. Scanning electron microscopy analysis showed the implanted stent surface was covered by endomembrane without thrombus formation. The endothelial cell in the membrane was clear and lined by the direction of blood flow. Histomorphological analysis revealed the neointima in normal stainless stent group was thicker than that in new drug eluting stent group, and the neointima was composed of smooth muscle cell and extracellular matrix. The result of this study shows that this kind of stent could reduce the rate of the re-stenosis and occlusion of PTCA. This stent can be used in clinical trials.

Study of a new medical stainless steel / 生物医学工程学杂志

Medical implantable stainless steels are widely used in medical field due to their excellent properties, besides its allergic response to human body, the nickel ion released from the steels due to corrosion has the harm of malformation and carcingenesis. The mechanical property, corrosion resistance and blood compatibility of a new nickel-free stainless steel (BIOSSN4) is researched in this paper. Compared with the traditional 316L medical stainless steel, BIOSSN4 shows wide future applications because of its better combination of strength and toughness, good corrosion resistance and biocompatibility.