School of Mechanical and Aerospace Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798, Republic of Singapore.
School of Mechanical and Aerospace Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798, Republic of Singapore.
Biosens Bioelectron. 2017 May 15;91:673-679. doi: 10.1016/j.bios.2017.01.023. Epub 2017 Jan 12.
A remarkable feature of biomaterials is their ability to deform in response to certain external bio-stimuli. Here, a novel biochemo-electro-mechanical model is developed for the numerical characterization of the urea-sensitive hydrogel in response to the external stimulus of urea. The urea sensitivity of the hydrogel is usually characterized by the states of ionization and denaturation of the immobilized urease, as such the model includes the effect of the fixed charge groups and temperature coupled with pH on the activity of the urease. Therefore, a novel rate of reaction equation is proposed to characterize the hydrolysis of urea that accounts for both the ionization and denaturation states of the urease subject to the environmental conditions. After examination with the published experimental data, it is thus confirmed that the model can characterize well the responsive behavior of the urea-sensitive hydrogel subject to the urea stimulus, including the distribution patterns of the electrical potential and pH of the hydrogel. The results point to an innovative means for generating electrical power via the enzyme-induced pH and electrical potential gradients, when the hydrogel comes in contact with the urea-rich solution, such as human urine.
生物材料的一个显著特点是它们能够响应某些外部生物刺激而变形。在这里，开发了一种新的生物化学-机电模型，用于数值表征水凝胶对尿素外部刺激的响应。水凝胶的尿素敏感性通常通过固定化脲酶的离子化和变性状态来表征，因此该模型包括固定电荷基团和温度与 pH 值对脲酶活性的影响。因此，提出了一种新的反应速率方程来描述尿素的水解，该方程考虑了脲酶的离子化和变性状态以及环境条件。通过与已发表的实验数据进行检验，证实该模型可以很好地描述尿素刺激下水凝胶的响应行为，包括水凝胶的电势和 pH 值的分布模式。结果表明，当水凝胶与富含尿素的溶液（如人体尿液）接触时，通过酶诱导的 pH 值和电势梯度可以产生电能，这是一种创新的方法。
