Self-Assembly of Large Gold Nanoparticles for Surface-Enhanced Raman Spectroscopy

Performance of portable technologies from mobile phones to electric vehicles is currently limited by the energy density and lifetime of lithium batteries. Expanding the limits of battery technology requires <i>in situ</i> detection of trace components at electrode–electrolyte interphases. Surface-enhance Raman spectroscopy could satisfy this need if a robust and reproducible substrate were available. Gold nanoparticles (Au NPs) larger than 20 nm diameter are expected to greatly enhance Raman intensity if they can be assembled into ordered monolayers. A three-phase self-assembly method is presented that successfully results in ordered Au NP monolayers for particle diameters ranging from 13 to 90 nm. The monolayer structure and Raman enhancement factors (EFs) are reported for a model analyte, rhodamine, as well as the best performing polymer electrolyte salt, lithium bis­(trifluoro­methane)­sulfonimide. Experimental EFs for the most part correlate with predictions based on monolayer geometry and with numerical simulations that identify local electromagnetic field enhancements. The EFs for the best performing Au NP monolayer are between 10⁶ and 10⁸ and give quantitative signal response when analyte concentration is changed

Sensitive and Bidirectional Detection of Urine Telomerase Based on the Four Detection-Color States of Difunctional Gold Nanoparticle Probe

Telomerase, a valuable biomarker, is highly correlated with the development of most of human cancers. Here, we develop a bidirectional strategy for telomerase activity detection and bladder cancer diagnosis based on four detection-color states of difunctional gold nanoparticle (GNP) probes such as blue, purple, red, and precipitate. Specifically, we define the red GNP probe as origin, which represents urine extracts with inactive telomerase and implies normal individuals. The forward direction is corresponding to the detection of a relatively high concentration of active telomerase, in which system GNP probes assemble obviously and precipitate, predicting bladder cancer samples. The negative direction is corresponding to extracts with a relatively low concentration (purple) and without any telomerase (blue), which can be differentiated by naked eyes or UV–vis spectrum, indicating bladder cancer and normal individuals, respectively. More importantly, this noninvasive strategy shows great sensitivity and selectivity when tested by 18 urine specimens from bladder cancer patients, inflammation, and normal individuals