Bogireddy Naveen Kumar Reddy, Agarwal Vivechana
Centro de Investigación en Ingeniería y Ciencias Aplicadas, UAEM Av. Univ. 1001, Col. Chamilpa Cuernavaca Mexico
RSC Adv. 2019 Dec 2;9(68):39834-39842. doi: 10.1039/c9ra08233f.
In this work, (Avocado) seed extract mediated systematically optimized synthesis has been employed for the formation of small sized gold nanoparticles (Av-AuNPs) at different pH values. The size, shape and crystallinity of the as-prepared AuNPs have been studied using transmission electron microscopy and X-ray diffraction. The nanoparticles were found to be selective towards mercury(ii) upon the prior or subsequent addition of iron(iii), revealing a blue shift and an enhancement of the characteristic surface plasmon resonance (at 519 nm). Similar absorbance based selectivity has been observed towards Fe(iii) in the presence of Hg(ii). The high sensitivity and selectivity of Av-AuNPs towards Hg(ii) and Fe(iii) has been attributed to the formation of core-shell structures. From the UV-visible spectroscopic measurements, the limits of detection for Hg(ii) and Fe(iii) are found to be 50 nM and 30 nM (around one order of magnitude less than the Environment Protection Agency limit of 0.7 μM for Fe(iii) in drinking water) respectively, with an excellent linear dependence over a wide range of concentrations. Additionally, as-prepared Av-AuNPs have been demonstrated to be efficient in the reduction of organic pollutant 4-nitrophenol to 4-aminophenol and degradation of some organic dyes, such as Methylene Blue, Direct blue, Rhodamine 6G, Bromophenol blue and methyl orange. The use of the proposed Av-AuNPs for sensing and green catalysis can form the basis of high-performance analytical assays, effective multiplexed intracellular sensors, and sophisticated and sustainable probes/catalysts.
在本研究中，采用了（鳄梨）种子提取物介导的系统优化合成方法，在不同pH值下制备了小尺寸金纳米颗粒（Av-AuNPs）。通过透射电子显微镜和X射线衍射研究了所制备金纳米颗粒的尺寸、形状和结晶度。发现这些纳米颗粒在预先或随后添加铁（III）后对汞（II）具有选择性，表现出特征表面等离子体共振（在519nm处）的蓝移和增强。在汞（II）存在下，对铁（III）也观察到了类似的基于吸光度的选择性。Av-AuNPs对汞（II）和铁（III）的高灵敏度和选择性归因于核壳结构的形成。通过紫外可见光谱测量，发现汞（II）和铁（III）的检测限分别为50 nM和30 nM（比环境保护局规定的饮用水中铁（III）的0.7 μM限值低约一个数量级），在很宽的浓度范围内具有良好的线性相关性。此外，所制备的Av-AuNPs已被证明能有效地将有机污染物4-硝基苯酚还原为4-氨基苯酚，并能降解一些有机染料，如亚甲基蓝、直接蓝、罗丹明6G、溴酚蓝和甲基橙。所提出的Av-AuNPs用于传感和绿色催化可成为高性能分析测定、有效的多重细胞内传感器以及精密且可持续的探针/催化剂的基础。
