Oćwieja Magdalena, Adamczyk Zbigniew, Morga Maria, Kubiak Katarzyna
Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239 Cracow, Poland.
Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239 Cracow, Poland.
J Colloid Interface Sci. 2015 May 1;445:205-212. doi: 10.1016/j.jcis.2014.12.071. Epub 2014 Dec 31.
Deposition mechanisms of citrate-stabilized silver nanoparticles 15 nm in diameter on cationic polyelectrolyte supporting layers were evaluated. Initially, the bulk and the electrokinetic properties of cationic polyelectrolytes and their monolayers on mica were determined using in situ streaming potential measurements. Analogously, the size distribution, stability and electrokinetic properties of silver particles were studied using transmission electron microscopy (TEM) and microelectrophoretic measurements. Afterward, the kinetics of silver particle deposition was quantitatively evaluated by a direct enumeration procedure exploiting the atomic force microscopy (AFM) and scanning electron microscopy (SEM) micrographs. Using this method the kinetics of particle adsorption was determined for various polyelectrolyte supporting layers as a function of ionic strength. These experiments were interpreted in terms of the random sequential adsorption (RSA) model. It was found that the highest coverage of 0.35 was obtained for silver monolayers deposited on poly(allylamine hydrochloride) (PAH)-modified mica in the case of higher ionic strength. The release kinetics of nanoparticles was also studied using the SEM and AFM imaging method. Using these experimental data the equilibrium adsorption constant and the binding energy of nanoparticles were calculated by exploiting the RSA approach. The investigations showed that the most stable silver monolayers are obtained for the poly-L-lysine (PLL) supporting layers where the 50% of particle is released after 441h, whereas in the case of PEI the release time was only 9h. These results are consistent with the model of discrete electrostatic interactions among ion pairs. Additionally, the obtained results have practical implication indicating that it is feasible to regulate the rate of silver nanoparticle release by a proper choice of the polyelectrolyte forming the supporting layer.
对直径为15 nm的柠檬酸盐稳定的银纳米颗粒在阳离子聚电解质支撑层上的沉积机制进行了评估。首先，使用原位流动电势测量法测定了阳离子聚电解质及其在云母上的单分子层的本体性质和电动性质。类似地，使用透射电子显微镜（TEM）和微电泳测量法研究了银颗粒的尺寸分布、稳定性和电动性质。随后，通过利用原子力显微镜（AFM）和扫描电子显微镜（SEM）显微照片的直接计数程序，对银颗粒沉积的动力学进行了定量评估。使用该方法，确定了各种聚电解质支撑层上颗粒吸附的动力学与离子强度的函数关系。这些实验根据随机顺序吸附（RSA）模型进行了解释。发现在较高离子强度的情况下，沉积在聚（烯丙胺盐酸盐）（PAH）修饰云母上的银单分子层的最高覆盖率为0.35。还使用SEM和AFM成像方法研究了纳米颗粒的释放动力学。利用这些实验数据，通过RSA方法计算了纳米颗粒的平衡吸附常数和结合能。研究表明，对于聚-L-赖氨酸（PLL）支撑层，获得了最稳定的银单分子层，其中50%的颗粒在441小时后释放，而在聚乙烯亚胺（PEI）的情况下，释放时间仅为9小时。这些结果与离子对之间离散静电相互作用的模型一致。此外，所获得的结果具有实际意义，表明通过适当选择形成支撑层的聚电解质来调节银纳米颗粒的释放速率是可行的。
