Chistè E, Ghafarinazari A, Donini M, Cremers V, Dendooven J, Detavernier C, Benati D, Scarpa M, Dusi S, Daldosso N
Department of Computer Science, Fluorescence Laboratory, University of Verona - Strada le Grazie 15, 37134 Verona, Italy.
J Mater Chem B. 2018 Mar 28;6(12):1815-1824. doi: 10.1039/c7tb02614e. Epub 2018 Mar 12.
Porous silicon (pSi) is a sponge-like material obtained by electrochemical etching of a crystalline silicon wafer. Due to quantum confinement effects, this material is photoluminescent and this is a fundamental property from the perspective of bioimaging applications. Limitations in nanomedicine to the use of photoluminescent pSi structures are mainly due to optical quenching in an aqueous environment and to the adverse effects of reactive groups introduced by etching procedures. In this work, we exploited an inorganic TiO coating of pSi microparticles by Atomic Layer Deposition (ALD) that resulted in optical stability of pSi particles in a biological buffer (e.g. PBS). The use of a rotary reactor allows deposition of a uniform coating on the particles and enables a fine tuning of its thickness. The ALD parameters were optimized and the photoluminescence (PL) of pSi-TiO microparticles was stabilized for more than three months without any significant effect on their morphology. The biocompatibility of the coated microparticles was evaluated by analyzing the release of cytokines and superoxide anion (O ) by human dendritic cells, which play an essential role in the regulation of inflammatory and immune responses. We demonstrated that the microparticles per se are unable to significantly damage or stimulate human dendritic cells and therefore are suitable candidates for nanomedicine applications. However, a synergistic effect of the microparticles with bacterial products, which are known to stimulate immune-response, was observed, indicating that a condition unfavorable to the use of inorganic nanomaterials in biological systems is the presence of infection diseases. These results, combined with the proved PL stability in biological buffers, open the way for the use of pSi-TiO microparticles as promising materials in nanomedicine, but their ability to increase immune cell activation by other agonists should be considered and even exploited.
多孔硅（pSi）是一种通过对晶体硅片进行电化学蚀刻而获得的海绵状材料。由于量子限制效应，这种材料具有光致发光特性，从生物成像应用的角度来看，这是一项基本特性。纳米医学中光致发光pSi结构应用的局限性主要归因于水环境中的光学猝灭以及蚀刻过程引入的反应基团的不利影响。在这项工作中，我们通过原子层沉积（ALD）利用无机TiO涂层对pSi微粒进行处理，这使得pSi微粒在生物缓冲液（如PBS）中具有光学稳定性。使用旋转反应器可使涂层均匀沉积在微粒上，并能对其厚度进行微调。优化了ALD参数，pSi-TiO微粒的光致发光（PL）稳定了三个多月，且对其形态没有任何显著影响。通过分析人树突状细胞释放的细胞因子和超氧阴离子（O）来评估包被微粒的生物相容性，人树突状细胞在炎症和免疫反应的调节中起着至关重要的作用。我们证明微粒本身不会显著损伤或刺激人树突状细胞，因此是纳米医学应用的合适候选材料。然而，观察到微粒与已知能刺激免疫反应的细菌产物之间存在协同效应，这表明在生物系统中不利于使用无机纳米材料的一个条件是存在感染性疾病。这些结果，结合在生物缓冲液中已证明的PL稳定性，为pSi-TiO微粒作为纳米医学中有前景的材料的应用开辟了道路，但应考虑甚至利用它们通过其他激动剂增强免疫细胞活化的能力。
