Sinduja B, John S Abraham
Centre for Nanoscience and Nanotechnology, Department of Chemistry, Gandhigram Rural Institute, Gandhigram, Dindigul, 624 302, India.
Anal Bioanal Chem. 2019 May;411(12):2597-2605. doi: 10.1007/s00216-019-01697-2. Epub 2019 Mar 2.
The present study illustrates the synthesis of silver nanoparticles capped with carbon dots (AgNPs-CDs) and their application towards the sensitive and selective sensing of sulfide ions by colorimetry and spectrofluorimetry methods. The CDs were prepared from l-asparagine by pyrolysis at 234 °C. The as-synthesized CDs were then utilized as reducing and capping agents for the synthesis of AgNPs-CDs by the wet chemical method. The size of the AgNPs-CDs was found to be ~ 5.2 nm. They show a characteristic surface plasmon resonance band at 417 nm and emission maximum at 441 nm when excited at 348 nm. Since the AgNPs were formed on the surface of CDs, the emission intensity of AgNPs-CDs was drastically decreased in contrast to that of CDs. The as-synthesized AgNPs-CDs were then successfully used for the sensitive and selective determination of sulfide ions. The addition of 0.1 μM sulfide ions to AgNPs-CDs leads to a decrease in the absorbance intensity at 417 nm aside turning from yellow to colorless. In the contrary, the emission was "turned on" after the addition of sulfide ions. The decrease in the absorbance and increase in the emission were attributed to the rapid formation of AgS. Finally, the practical application of the present method was demonstrated by determining dissolved HS in tap water samples.
本研究阐述了碳点包覆的银纳米颗粒（AgNPs-CDs）的合成及其通过比色法和荧光光谱法对硫化物离子进行灵敏且选择性传感的应用。碳点由L-天冬酰胺在234℃下热解制备而成。然后，将合成的碳点用作还原剂和封端剂，通过湿化学法合成AgNPs-CDs。发现AgNPs-CDs的尺寸约为5.2纳米。当在348纳米激发时，它们在417纳米处显示出特征性的表面等离子体共振带，在441纳米处发射强度最大。由于银纳米颗粒在碳点表面形成，与碳点相比，AgNPs-CDs的发射强度急剧下降。合成的AgNPs-CDs随后成功用于灵敏且选择性地测定硫化物离子。向AgNPs-CDs中加入0.1微摩尔的硫化物离子，除了颜色从黄色变为无色外，还导致417纳米处的吸光度强度降低。相反，加入硫化物离子后发射“开启”。吸光度的降低和发射的增加归因于AgS的快速形成。最后，通过测定自来水样品中的溶解HS证明了本方法的实际应用。
