In the research,a β-hydroxybutyrate and β-hydroxyvalerate copolymer(PHBV)/polylactic acid(PLA)artificial blood vessel was designed and developed,and it was also implanted in vivo for a period of time to observe its biocompatibility and degradation performance.The results showed that the developed PHBV/PLA artificial blood vessel could be used to replace the natural blood vessel,but its degradation rate was too fast and the mechanical supporting force was insufficient.Thus,properties of the PHBV/PLA need to be further improved.
The main disadvantage of conventional ureteral stents commonly used to provide urinary drainage after urological practice is that the patients have to undergo a secondary surgical procedure to remove stents. A new braided thin-walled biodegradable ureteral stent composed of PGA (polyglycolic acid) and PLGA (copolymer of polylactic and polyglycolic acid) multifilaments was evaluated in vitro in this study. In vitro degradation was performed in artificial urine with pH of 5.8 and the temperature of 37℃. The mass loss, mechanical properties, and morphology were observed at different degradaing time intervals of 0, 1, 2, 3, 4, and 5 weeks. The stent had a thinner wall than those of other degradable stents and provided better mechanical properties. The braided thin-walled biodegradable ureteral stents began to degrade after 2 weeks. At the week of 5, the stents were fully degraded. The degradative process of stents is smooth and well controlled.
The optimal vascular blood supply throughout the body guarantees the support of normal functions to tissues and organs.Implants are now becoming a seamless extension of the body and shall accompany a higher level of fidelity between the device and the patient.As regenerative medicine is still in its infancy,the ongoing search for new and effective prosthetic alternatives continues to be essential and highly rewarding.Thanks in part to the progress of imaging and the benefits of 3D printing,previously unimagined emergent technologies are at hand.The emerging technologies of the last few decades and the near future will continue to greatly improve both the quality and quantity of patients' lives.They focus on minimally invasive technologies(keyhole surgery) and approaches for deployment of valves,stent-grafts,leadless pacemakers and adaptation of medical devices for destination therapy(assist devices and artificial hearts).In addition,specific blood conduits for the aortic valves together with the aortic arch and the pulmonary valves are considered.These breakthroughs are currently at various stages of development and acceptability.Innovative biomaterials were essential in the development of cardiovascular devices.They were and they still are the essential support for conduction prosthesis,but their place in signal prosthesis is being revisited.Any new development in medical devices has been frequently driven by surgeons and industry.The emergent technologies are introduced by pioneers.The risks and benefits of devices must be continuously reassessed during the lifetime of the implants based upon sound scientific principles of investigation,clinical experience of the users and retrieval programs.
Chitosan(CS)nanofibers containing silver nanoparticles(AgNPs)were prepared by in-situ reducing method.A water soluble carboxymethyl chitosan(CMCT)was applied for the preparation of AgNPs.The impact factor such as the concentration of CMCT,silver nitrate(AgNO_3)content,temperature and the heating time during the preparation of AgNPs were studied.The result showed that the proper value of the concentration of CMCT,AgNO_3content,temperature and the heating time were set as0.1%,20μL AgNO_3(1.7 mol/L),90°and 3 h,separately and the maximum concentration of AgNPs could be acquired.To solve the spinnability of chitosan nanofiber,a super high molecular weight polyethylene oxide(PEO)was introduced to the system,and a new mixed solvent system was prepared by adding acetic acid,dimethyl sulfoxide(DMSO)and several drops of Triton X-100TMto distilled water.CS/PEO(80/20)with the concentration of 3%was dissolved in the mixed solvent to prepare electrospinning solution for CS/PEO(80/20)nanofiber fabrication.The CS containing AgNPs electrospun solution could be prepared by replacing the distilled water to silver nanoparticle solution during the preparation of mixed solvent.Ultraviolet visible(UV-Vis)spectra and transmission electron microscope(TEM)results showed that silver nanoparticles were prepared successfully.CS membranes with and without AgNPs were acquired via a traditional electrospinning equipment.These two nanofiber membranes were characterized by scanning electron microscope(SEM)images and mechanical testing.It could be noticed from the SEM images that there was a good morphology and random distribution for the nanofibers with an average fiber diameter of 180 nm.The mechanical property results showed that the addition of AgNPs decreased the mechanical strength significantly but the mechanical strength could still support wound dressing application.
