Zhang Zhihua, Du Guangsheng, Sun Xun, Zhang Zhibing
School of Chemical Engineering, University of Birmingham, Birmingham B15 2TT, UK.
Changzhou Institute of Advanced Manufacturing Technology, Changzhou 213164, China.
Materials (Basel). 2023 Feb 21;16(5):1769. doi: 10.3390/ma16051769.
Microneedles, including dissolvable ones made from biocompatible and biodegradable materials, have been widely studied and can potentially be used for transdermal drug delivery, disease diagnosis (sampling), skin care, etc. Characterizing their mechanical properties is essential, as being mechanically strong enough to pierce the skin barrier is one of the most fundamental and crucial requirements for them. The micromanipulation technique was based on compressing single microparticles between two flat surfaces to obtain force and displacement data simultaneously. Two mathematical models had already been developed to calculate the rupture stress and apparent Young's modulus, which can identify variations of these parameters in single microneedles within a microneedle patch. In this study, a new model has been developed to determine the viscoelasticity of single microneedles made of hyaluronic acid (HA) with a molecular weight of 300 kDa loaded with lidocaine by using the micromanipulation technique to gather experimental data. The modelling results from the micromanipulation measurements suggest that the microneedles were viscoelastic and their mechanical behaviour was strain-rate dependent, which implies that the penetration efficiency of viscoelastic microneedles can be improved by increasing their piercing speed into the skin.
微针，包括由生物相容性和可生物降解材料制成的可溶解微针，已经得到了广泛研究，并有可能用于透皮给药、疾病诊断（采样）、皮肤护理等。表征它们的机械性能至关重要，因为具有足够的机械强度以穿透皮肤屏障是对它们最基本和关键的要求之一。微操纵技术是基于在两个平面之间压缩单个微粒以同时获得力和位移数据。已经开发了两个数学模型来计算破裂应力和表观杨氏模量，这可以识别微针贴片内单个微针中这些参数的变化。在本研究中，通过使用微操纵技术收集实验数据，开发了一种新模型来确定由负载利多卡因的分子量为300 kDa的透明质酸（HA）制成的单个微针的粘弹性。微操纵测量的建模结果表明，微针具有粘弹性，并且它们的机械行为取决于应变率，这意味着通过提高微针刺入皮肤的速度可以提高粘弹性微针的穿透效率。
