结直肠癌 (CRC) 是全球第二大癌症相关死亡原因，尤其是年轻人中的患病率每年都在增加。在寻找治疗该疾病的创新方法的过程中，药物输送系统（DDS）因其独特的特性而前景广阔，可以通过降低药物浓度来改善治疗效果，克服耐药性，同时潜在地减少副作用。丝素蛋白是一种生物聚合物，可经过加工以获得生物相容性和可生物降解的纳米颗粒，这些纳米颗粒可以通过小分子治疗药物的表面吸附有效负载，并通过调节其药代动力学来允许其运输和持续释放。金诺芬 (AF) 最近因其强大的抗癌活性而被重新利用，目前正在进行临床试验。其作用机制是通过抑制硫氧还蛋白还原酶，硫氧还蛋白还原酶在多种细胞内过程中发挥重要作用，并在某些肿瘤中过度表达。考虑到AF在水中的溶解度较低，我们提出丝素蛋白纳米颗粒（SFN）作为AF载体，以提高其生物利用度，增加细胞吸收并防止其降解或避免一些耐药机制。在此，我们报告了一种负载 AF 的丝素蛋白纳米粒子 (SFN-AF) 新配方的制备和表征，其与 FITC 的功能化用于分析细胞摄取，以及其对人结直肠癌细胞系 (HT29) 的细胞毒活性和 HCT116）在 2D 和 3D 细胞培养中。 3D 球体模型提供了一个模拟体内观察到的 CRC 3D 方面的 3D 环境，并代表了筛选治疗 CRC 的疗法的有效 3D 环境。负载的纳米粒子呈现出球形形态，流体动力学直径为~ 160 nm，并且由于其负表面电荷而在水溶液中具有良好的稳定性。 FESEM-EDX 分析显示纳米粒子表面上具有高电子密度的金簇均匀分布。 SFN-AF 在 37°C 磷酸盐缓冲液中孵育 10 天，释放 77% 的负载 AF，显示出最初的爆发，然后持续释放。流式细胞术分析表明 FITC-SFN-AF 被两种细胞系有效内化，这通过共焦显微镜成像得到证实。 SFN 增强了两种 CRC 系二维培养物中 AF 的细胞毒性。在 3D 培养中也获得了有希望的结果，为未来将该策略应用于 CRC 治疗铺平了道路。© 2024。控释协会。

Colorectal cancer (CRC) is the second most common cause of cancer related deaths worldwide and the prevalence in young people especially is increasing annually. In the search for innovative approaches to treat the disease, drug delivery systems (DDS) are promising owing to their unique properties, which allow improved therapeutic results with lower drug concentrations, overcoming drug resistance and at the same time potentially reducing side effects. Silk fibroin is a biopolymer that can be processed to obtain biocompatible and biodegradable nanoparticles that can be efficiently loaded by surface adsorption with small-molecule therapeutics and allow their transport and sustained release by modulating their pharmacokinetics. Auranofin (AF) has recently been repurposed for its strong anticancer activity and is currently in clinical trials. Its mechanism of action is through the inhibition of thioredoxin reductase enzymes, which play an essential role in several intracellular processes and are overexpressed in some tumours. Taking into account that AF has a low solubility in water, we propose silk fibroin nanoparticles (SFN) as AF carrier in order to improve its bioavailability, increasing cellular absorption and preventing its degradation or avoiding some resistance mechanisms. Here we report the preparation and characterization of a new formulation of AF-loaded silk fibroin nanoparticles (SFN-AF), its functionalization with FITC for the analysis of cellular uptake, as well as its cytotoxic activity against cell lines of human colorectal cancer (HT29 and HCT116) in both 2D and 3D cell cultures. 3D spheroid models provide a 3D environment which mimics the 3D aspects of CRC observed in vivo and represents an effective 3D environment to screen therapeutics for the treatment of CRC. The loaded nanoparticles showed a spherical morphology with a hydrodynamic diameter of ~ 160 nm and good stability in aqueous solution due to their negative surface charges. FESEM-EDX analysis revealed a homogeneous distribution of Au clusters with high electron density on the surface of the nanoparticles. SFN-AF incubated in phosphate buffer at 37 °C released 77% of the loaded AF over 10 days, showing an initial burst and then sustained release. Flow cytometry analysis showed that FITC-SFN-AF was efficiently internalized by both cell lines, which was confirmed by confocal microscopy imaging. SFN enhanced the cytotoxicity of AF in 2D cultures in both CRC lines. Promising results were also obtained in 3D culture paving the way for future application of this strategy as a therapy for CRC.© 2024. Controlled Release Society.