Libera Valeria, Malaspina Rocco, Bittolo Bon Silvia, Cardinali Martina Alunni, Chiesa Irene, De Maria Carmelo, Paciaroni Alessandro, Petrillo Caterina, Comez Lucia, Sassi Paola, Valentini Luca
Dipartimento di Fisica e Geologia, Università degli Studi di Perugia Via A. Pascoli 06123 Perugia Italy.
Department of Chemistry, Biology and Biotechnology, University of Perugia Via Elce di Sotto 8 06123 Perugia Italy.
RSC Adv. 2024 Jul 15;14(31):22393-22402. doi: 10.1039/d4ra02830a. eCollection 2024 Jul 12.
3D printing of water stable proteins with elastic properties offers a broad range of applications including self-powered biomedical devices driven by piezoelectric biomaterials. Here, we present a study on water-soluble silk fibroin (SF) films. These films were prepared by mixing degummed silk fibers and calcium chloride (CaCl) in formic acid, resulting in a silk I-like conformation, which was then converted into silk II by redissolving in phosphate buffer (PBS). Circular dichroism, Raman and infrared (IR) spectroscopies were used to investigate the transitions of secondary structure in silk I and silk II as the pH of the solvent and the sonication time were changed. We showed that a solvent with low pH ( 4) maintains the silk I β-turn structure; in contrast solvent with higher pH ( 7.4) promotes β-sheet features of silk II. Ultrasonic treatment facilitates the transition to water stable silk II only for the SF redissolved in PBS. SF from pH 7.4 solution has been printed using extrusion-based 3D printing. A self-powered memristor was realized, comprising an SF-based electric generator and an SF 3D-printed memristive unit connected in series. By exploiting the piezoelectric properties of silk II with higher β-sheet content and Ca ion transport phenomena, the application of an input voltage driven by a SF generator to SF 3D printed holey structures induces a variation from an initial low resistance state (LRS) to a high resistance state (HRS) that recovers in a few minutes, mimicking the transient memory, also known as short-term memory. Thanks to this holistic approach, these findings can contribute to the development of self-powered neuromorphic networks based on biomaterials with memory capabilities.
具有弹性特性的水稳定蛋白质的3D打印具有广泛的应用,包括由压电生物材料驱动的自供电生物医学设备。在此,我们展示了一项关于水溶性丝素蛋白(SF)薄膜的研究。这些薄膜是通过将脱胶丝纤维和氯化钙(CaCl)在甲酸中混合制备而成,形成类似丝I的构象,然后通过在磷酸盐缓冲液(PBS)中重新溶解转化为丝II。利用圆二色性、拉曼光谱和红外(IR)光谱来研究随着溶剂pH值和超声处理时间的变化,丝I和丝II二级结构的转变。我们发现,低pH值(4)的溶剂维持丝I的β-转角结构;相反,高pH值(7.4)的溶剂促进丝II的β-折叠特征。仅对于在PBS中重新溶解的SF,超声处理有助于向水稳定的丝II转变。已使用基于挤出的3D打印技术打印了来自pH 7.4溶液的SF。实现了一个自供电忆阻器,它由一个基于SF的发电机和一个串联的SF 3D打印忆阻单元组成。通过利用具有较高β-折叠含量的丝II的压电特性和Ca离子传输现象,由SF发电机驱动的输入电压施加到SF 3D打印的多孔结构上会引起从初始低电阻状态(LRS)到高电阻状态(HRS)的变化,该变化在几分钟内恢复,模拟了瞬态记忆,也称为短期记忆。由于这种整体方法,这些发现有助于基于具有记忆能力的生物材料开发自供电神经形态网络。
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