Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India.
J Colloid Interface Sci. 2012 Oct 1;383(1):130-9. doi: 10.1016/j.jcis.2012.06.033. Epub 2012 Jun 26.
Multilayers of poly(diallyldimethylammonium chloride) (PDDA) and citrate capped Au nanoparticles (AuNPs) anchored on sodium 3-mercapto-1-propanesulfonate modified gold electrode by electrostatic layer-by-layer assembly (LbL) technique are shown to be an excellent architecture for the direct electrochemical oxidation of As(III) species. The growth of successive layers in the proposed LbL architecture is followed by atomic force microscopy, UV-vis spectroscopy, quartz crystal microbalance with energy dissipation, and electrochemistry. The first bilayer is found to show rather different physico-chemical characteristics as compared to the subsequent bilayers, and this is attributed to the difference in the adsorption environments. The analytical utility of the architecture with five bilayers is exploited for arsenic sensing via the direct electrocatalytic oxidation of As(III), and the detection limit is found to be well below the WHO guidelines of 10ppb. When the non-redox active PDDA is replaced by the redox-active Os(2,2'-bipyridine)(2)Cl-poly(4-vinylpyridine) polyelectrolyte (PVPOs) in the LbL assembly, the performance is found to be inferior, demonstrating that the redox activity of the polyelectrolyte is futile as far as the direct electro-oxidation of As(III) is concerned.
层层聚二烯丙基二甲基氯化铵（PDDA）和柠檬酸钠封端的金纳米粒子（AuNPs）通过静电层层组装（LbL）技术锚定在 3-巯基-1-丙磺酸修饰的金电极上，被证明是一种直接电化学氧化 As(III)物种的优异结构。通过原子力显微镜、紫外可见光谱、石英晶体微天平（带有能量耗散）和电化学来跟踪所提出的 LbL 结构中连续层的生长。发现前两个双层与后续双层相比表现出相当不同的物理化学特性，这归因于吸附环境的差异。该结构具有五层，可用于通过直接电催化氧化 As(III)进行砷传感，检测限远低于世界卫生组织规定的 10ppb。当非氧化还原活性的 PDDA被氧化还原活性的 Os(2,2'-联吡啶)(2)Cl-聚(4-乙烯基吡啶)聚电解质（PVPOs）取代时，性能发现不如预期，表明聚电解质的氧化还原活性对于直接电氧化 As(III)来说是无益的。
