Search

Drug eluting stents (DES) can efficiently reduce the atherosclerosis and restenosis issues of coronary artery as compared to bare metal stents due to the presence of pharmaceutically active agent on their surface. Nevertheless, the arising safety concerns of DES such as delayed healing and late in stent restenosis and thrombus, has stirred the research efforts to improve the outcomes of the DES. In this connection, attention is being shifted from the use of synthetic drug to natural drug for DES. In the present work, natural compound loaded polymeric films were synthesized and their antioxidant and anticoagulation capabilities were assessed through in vitro testing. The potential of the drug loaded polymeric films to curb the production of free radicals was evaluated by carrying out antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The in vitro platelet adhesion was investigated through static platelet adhesion test while effect of synthesized films on intrinsic coagulation pathway was investigated through activated partially thromboplastin time (APTT). Moreover, to further evaluate the blood compatibility of the developed drug loaded films, in vitro hemolytic and anti-thrombolytic assays were carried out. The obtained results indicated that, incorporating herbal compounds such as ginger, magnolol and curcumin, in polymeric matrix (PVA) has significantly improved the blood compatibility of the polymeric films. Hence, it can be concluded that the synthesized drug loaded polymeric films have the potential capability to be used as a potential coating material for coating biomedical implants with good anticoagulation and antioxidant property to cater the cardiovascular issues such as atherosclerosis, restenosis and thrombus formation.

Background Auxetic materials tend to exhibit stretching in the direction of the applied load as well as in the perpendicular direction. This may be an inherent property of the material, or it might be a particular structural characteristic that confers it with auxetic properties. In this study, the auxetic properties of a rotating squares auxetic design were utilized in tandem with a stretching mechanism to manufacture a device that offers the advantages of adjustable pore size and hence tunable drug delivery characteristics. Methods An auxetic polyurethane film was fabricated through the polymer casting technique. An acrylonitrile-butadiene-styrene (ABS) plastic mold for polymer casting was made through additive manufacturing. Stereolithography was used for fabrication of the mechanism that controlled pore size of the polymeric auxetic film. A laminate arrangement of the film and the mechanism was devised, through which movement of the mechanism controlled stretching of the auxetic film underneath. Results Results were analyzed through image processing. It was observed that a 2-dimensional increase (in length and width) of the auxetic film took place that corresponded to an increase in pore size of the film. Several mathematical correlations were drawn up. Conclusions It may be concluded that the first factor controlling drug release kinetics is the pore size of the film. This study explored a prototype mechanism that has the potential for being used in devices for controlled drug delivery or in smart bandage systems that may enhance wound healing in chronic wound treatment.

Background Auxetics, a special class of materials, tend to expand both in the radial and longitudinal directions when a unidirectional tensile force is applied. Recently, studies have come up with new designs for auxetic vascular and nonvascular stents which are deployed with commercial balloon catheters. There are some inherent limitations associated with a unidirectional application of expansion force in the effective deployment of stents. This work proposed a solution to some of these limitations through the use of a biaxial mode of a predetermined strain-based expansion mechanism. Method The design incorporated a pressure-activated crank-slider mechanism. Fabrication of a prototype for experimental verification was carried out through milling and high-speed lathe machining. The testing of the device employed the use of auxetic stents, fabricated from a biocompatible polymer. A finite element study is presented to extrapolate experimental results to a broader range of operation and working conditions. Results and Conclusions The expansion mechanism is similar in operation to the opening of an umbrella. The length of the connected auxetic stent increases when internal hydraulic pressure is applied. The degree of linear expansion in 1 direction influences the expansion of auxetic stent in the lateral direction. As the device exerts pressure longitudinally, a larger amount of the force is distributed on the unit cells/hinges which ultimately results in an increased expansion of the stent.

Background Cardiovascular heart disease is one of the leading health issues in the present era and requires considerable health care resources to prevent it. The present study was focused on the development of a new coronary stent based on novel auxetic geometry which enables the stent to exhibit a negative Poisson's ratio. Commercially available coronary stents have isotropic properties, whereas the vascular system of the body shows anisotropic characteristics. This results in a mismatch between anisotropic–isotropic properties of the stent and arterial wall, and this in turn is not favorable for mechanical adhesion of the commercially available coronary stents with the arterial wall. It is believed that an auxetic coronary stent with inherent anisotropic mechanical properties and negative Poisson's ratio will have good mechanical adhesion with the arterial wall. Methods The auxetic design was obtained via laser cutting, and surface treatment was performed with acid pickling and electropolishing, followed by an annealing process. In vitro mechanical analysis was performed to analyze the mechanical performance of the auxetic coronary stent. Scanning electronic microscopy (SEM) was used to determine the effects of fabrication processes on the topography of the auxetic stent. Results and Conclusions The elastic recoil (3.3%) of the in vitro mechanical analysis showed that the auxetic stent design effectively maintained the luminal patency of the coronary artery. Also, the auxetic coronary stent showed no foreshortening, therefore it avoids the problem of stent migration, by expanding in both the radial and longitudinal directions. By virtue of its synclastic behavior, the auxetic stent bulges outward when it is radially expanded through an inflated balloon.