Mir Mariam, Ansari Umar, Najabat Ali Murtaza
Biomedical Engineering and Sciences Department, School of Mechanical and Manufacturing Engineering, National University of Sciences and Technology (NUST), Islamabad - Pakistan.
J Appl Biomater Funct Mater. 2017 Jan 26;15(1):e63-e69. doi: 10.5301/jabfm.5000280. Epub 2016 Oct 10.
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.
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 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.
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.
拉胀材料在施加负载的方向以及垂直方向上往往都会发生拉伸。这可能是材料的固有属性，也可能是赋予其拉胀特性的特定结构特征。在本研究中，旋转方形拉胀设计的拉胀特性与拉伸机制协同作用，制造出一种具有孔径可调优势从而具备可调节药物递送特性的装置。
通过聚合物浇铸技术制备了一种拉胀聚氨酯薄膜。通过增材制造制作了用于聚合物浇铸的丙烯腈-丁二烯-苯乙烯（ABS）塑料模具。采用立体光刻技术制造控制聚合物拉胀薄膜孔径的机制。设计了薄膜与该机制的层压结构，通过该结构，机制的运动控制下方拉胀薄膜的拉伸。
通过图像处理对结果进行分析。观察到拉胀薄膜在二维方向（长度和宽度）上有所增加，这与薄膜孔径的增加相对应。得出了几个数学相关性。
可以得出结论，控制药物释放动力学的首要因素是薄膜的孔径。本研究探索了一种原型机制，该机制有潜力用于控释给药装置或智能绷带系统，在慢性伤口治疗中可能会促进伤口愈合。
