Utembe Wells, Potgieter Kariska, Stefaniak Aleksandr Byron, Gulumian Mary
National Institute for Occupational Health, PO Box 4788, Johannesburg, 2000, South Africa.
University of Malawi, Malawi Polytechnic, Blantyre, Malawi.
Part Fibre Toxicol. 2015 Apr 28;12:11. doi: 10.1186/s12989-015-0088-2.
Biopersistence and biodurability have the potential to influence the long-term toxicity and hence pathogenicity of particles that deposit in the body. Therefore, biopersistence and biodurability are considered to be important parameters needed for the risk assessment of particles and fibres. Dissolution, as a measure of biodurability, is dependent on the chemical and physical properties (size, surface area, etc.) of particles and fibres and also of the suspension medium including its ionic strength, pH, and temperature. In vitro dissolution tests can provide useful insights as to how particles and fibres may react in biological environments; particles and fibres that release ions at a higher rate when suspended in vitro in a specific simulated biological fluid will be expected to do so when they exist in a similar biological environment in vivo. Dissolution of particles and fibres can follow different reaction kinetics. For example, the majority of micro-sized particles and fibres follow zero-order reaction kinetics. In this case, although it is possible to calculate the half-time of a particle or fibre, such calculation will be dependent on the initial concentration of the investigated particle or fibre. Such dependence was eliminated in the shrinking sphere and fibre models where it was possible to estimate the lifetimes of particles and fibres as a measure of their biodurability. The latter models can be adapted for the dissolution studies of nanomaterials. However, the models may apply only to nanomaterials where their dissolution follows zero-order kinetics. The dissolution of most nanomaterials follows first-order kinetics where dependence on their initial concentration of the investigated nanomaterials is not required and therefore it is possible to estimate their half-times as a measure of their biodurability. In dissolution kinetics for micro-sized and nano-sized particles and fibres, knowledge of dissolution rate constants is necessary to understand biodurability. Unfortunately, many studies on dissolution of nanoparticles and nanofibres do not determine the dissolution rates and dissolution rate constants. The recommendation is that these parameters should be considered as part of the important descriptors of particle and fibre physicochemical properties, which in turn, will enable the determination of their biodurability.
生物持久性和生物耐久性有可能影响沉积在体内的颗粒的长期毒性，进而影响其致病性。因此，生物持久性和生物耐久性被认为是颗粒和纤维风险评估所需的重要参数。溶解作为生物耐久性的一种衡量方式，取决于颗粒和纤维的化学和物理性质（尺寸、表面积等），也取决于悬浮介质的性质，包括其离子强度、pH值和温度。体外溶解试验可以提供关于颗粒和纤维在生物环境中可能如何反应的有用见解；当颗粒和纤维在体外悬浮于特定模拟生物流体中时以较高速率释放离子，那么当它们存在于体内类似生物环境中时预计也会如此。颗粒和纤维的溶解可以遵循不同的反应动力学。例如，大多数微米级颗粒和纤维遵循零级反应动力学。在这种情况下，虽然可以计算颗粒或纤维的半衰期，但这种计算将取决于所研究颗粒或纤维的初始浓度。在收缩球体和纤维模型中消除了这种依赖性，在这些模型中可以估计颗粒和纤维的寿命，作为其生物耐久性的一种衡量方式。后一种模型可用于纳米材料的溶解研究。然而，这些模型可能仅适用于溶解遵循零级动力学的纳米材料。大多数纳米材料的溶解遵循一级动力学，在这种情况下不需要依赖所研究纳米材料的初始浓度，因此可以估计它们的半衰期，作为其生物耐久性的一种衡量方式。在微米级和纳米级颗粒及纤维的溶解动力学中，了解溶解速率常数对于理解生物耐久性是必要的。不幸的是，许多关于纳米颗粒和纳米纤维溶解的研究并未确定溶解速率和溶解速率常数。建议应将这些参数视为颗粒和纤维物理化学性质的重要描述符的一部分，这反过来将有助于确定它们的生物耐久性。
