Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral Street, G4 0RE Glasgow, U.K.
Jena Center for Soft Matter (JCSM), Friedrich-Schiller-University, Philosophenweg 7, 07743 Jena, Germany.
ACS Biomater Sci Eng. 2020 May 11;6(5):2796-2804. doi: 10.1021/acsbiomaterials.0c00202. Epub 2020 Apr 20.
Silk has a long track record of clinical use in the human body, and new formulations, including silk nanoparticles, continue to reveal the promise of this natural biopolymer for healthcare applications. Native silk fibroin can be isolated directly from the silk gland, but generating sufficient material for routine studies is difficult. Consequently, silk fibroin, typically extracted from cocoons, serves as the source for nanoparticle formation. This silk requires extensive processing (e.g., degumming, dissolution, etc.) to yield a hypoallergenic aqueous silk stock, but the impact of processing on nanoparticle production and characteristics is largely unknown. Here, manual and microfluidic-assisted silk nanoparticle manufacturing from 60- and 90-min degummed silk yielded consistent particle sizes (100.9-114.1 nm) with low polydispersity. However, the zeta potential was significantly lower ( < 0.05) for microfluidic-manufactured nanoparticles (-28 to -29 mV) than for manually produced nanoparticles (-39 to -43 mV). Molecular weight analysis showed a nanoparticle composition similar to that of the silk fibroin starting stock. Reducing the molecular weight of silk fibroin reduced the particle size for degumming times ≤30 min, whereas increasing the molecular weight polydispersity improved the nanoparticle homogeneity. Prolonged degumming (>30 min) had no significant effect on particle attributes. Overall, the results showed that silk fibroin processing directly impacts nanoparticle characteristics.
丝绸在人体临床应用方面有着悠久的历史，新的配方，包括丝纳米粒子，继续为这种天然生物聚合物在医疗保健应用方面的应用带来希望。天然丝素蛋白可以直接从丝腺中分离出来，但要获得足够用于常规研究的材料却很困难。因此，丝素蛋白通常从蚕茧中提取，作为纳米粒子形成的来源。这种丝绸需要进行大量的处理（例如脱胶、溶解等），以产生低致敏性的水丝原料，但处理对纳米颗粒生产和特性的影响在很大程度上是未知的。在这里，从 60 分钟和 90 分钟脱胶的丝绸中通过手动和微流控辅助制造的丝纳米粒子产生了一致的粒径（100.9-114.1nm），且多分散性较低。然而，微流控制造的纳米粒子的 zeta 电位（-28 至-29mV）明显低于手动制造的纳米粒子（-39 至-43mV）。分子量分析表明，纳米粒子的组成与丝素蛋白起始原料相似。降低丝素蛋白的分子量会减小脱胶时间≤30 分钟的粒径，而增加分子量的多分散性则会提高纳米粒子的均一性。延长脱胶时间（>30 分钟）对颗粒特性没有显著影响。总的来说，结果表明，丝素蛋白的处理直接影响纳米颗粒的特性。
