da Rosa Everton Luis Santos
Laboratory of Biochemistry and Protein Chemistry, Department of Cell Biology, University of Brasilia, Campus Darcy Ribeiro, Brasilia 70910-900, Brazil.
BMC Biophys. 2013 Aug 19;6(1):11. doi: 10.1186/2046-1682-6-11.
Increasing applications of titanium dioxide (TiO2) fine particles (FPs) and nanoparticles (NPs) require coupled knowledge improvement concerning their biokinetic effects. Neutrophils are quickly recruited to titanium implantation areas. Neutrophils mechanical properties display a crucial role on cell physiology and immune responsive functions. Then, micro and nanomechanical characterization assessed by force spectroscopy (FS) technique has been largely applied in this field.
Scanning electron microscopy (SEM) images highlighted neutrophils morphological changes along TiO2 FPs and NPs aggregates exposure time (1, 5, and 30 min) compared to controls. FS approaches showed an increasing on attraction forces to TiO2 FPs and NPs treated neutrophils. This group depicted stronger stiffness features than controls just at 1 min of exposure. Treated neutrophils showed a tendency to increase adhesive properties after 1 and 5 min of exposure. These cells maintained comparatively higher elasticity behavior for a longer time possibly due to intense phagocytosis and cell stiffness opposing to the tip indentation. Neutrophils activation caused by FPs and NPs uptake could be related to increasing dissipated energy results.
Mechanical modifications resulted from TiO2 FPs and NPs aggregates interaction with neutrophils showed increasing stiffness and also cell morphology alteration. Cells treatment by this metal FPs and NPs caused an increase in attractive forces. This event was mainly observed on the initial exposure times probably regarding to the interaction of neutrophils membrane and phagocytosis. Similar results were found to adhesion forces and dissipated energy outcomes. Treated cells presented comparatively higher elasticity behavior for a longer time. SEM images clearly suggested cell morphology alteration along time course probably related to activation, cytoskeleton rearrangement and phagocytosis. This scenario with increase in stiffness strongly suggests a direct relationship over neutrophil rolling, arrest, and transmigration. Scrutinizing these interactions represents an essential step to clarify the mechanisms involved on treatments containing micro and nanomaterials and their fates on the organisms.
二氧化钛（TiO₂）细颗粒（FPs）和纳米颗粒（NPs）的应用日益广泛，这就需要我们加深对其生物动力学效应的认识。中性粒细胞会迅速被招募到钛植入区域。中性粒细胞的力学特性在细胞生理和免疫反应功能中起着关键作用。因此，通过力谱（FS）技术进行的微观和纳米力学表征已在该领域得到广泛应用。
扫描电子显微镜（SEM）图像显示，与对照组相比，中性粒细胞在暴露于TiO₂ FPs和NPs聚集体的不同时间（1、5和30分钟）后形态发生了变化。FS方法显示，处理后的中性粒细胞对TiO₂ FPs和NPs的吸引力增加。该组在暴露仅1分钟时就表现出比对照组更强的硬度特征。处理后的中性粒细胞在暴露1分钟和5分钟后显示出粘附特性增加的趋势。这些细胞在较长时间内保持相对较高的弹性行为，这可能是由于强烈的吞噬作用以及细胞硬度抵抗尖端压痕所致。FPs和NPs摄取引起的中性粒细胞活化可能与耗散能量增加有关。
TiO₂ FPs和NPs聚集体与中性粒细胞相互作用导致的力学改变表现为硬度增加以及细胞形态改变。这种金属FPs和NPs对细胞的处理导致吸引力增加。这一现象主要在初始暴露时间观察到，可能与中性粒细胞膜的相互作用和吞噬作用有关。在粘附力和耗散能量结果方面也发现了类似的结果。处理后的细胞在较长时间内表现出相对较高的弹性行为。SEM图像清楚地表明，随着时间推移细胞形态发生改变，这可能与活化作用、细胞骨架重排和吞噬作用有关。这种硬度增加的情况强烈表明与中性粒细胞的滚动、停滞和迁移存在直接关系。仔细研究这些相互作用是阐明涉及微米和纳米材料处理的机制及其在生物体中的命运的重要一步。
