Apr 17, 2014
Copper nanoclusters show promise in detecting hydrogen sulfide
Hydrogen sulfide (H2S) has a dual role as both a poisonous gas in large concentrations, yet a facilitator of many biological processes such as muscle relaxation in trace concentrations. Sensitive and selective probes for the rapid detection of H2S are therefore urgently needed. Reporting in Nanotechnology, researchers unveil a promising route to prepare luminescent copper nanoclusters (Cu NCs) for the detection of H2S. The practicality is tested through the analysis of poisonous gas in hot spring water samples.
Among the many techniques for the sensing of H2S, fluorescence has the advantage of sensitivity, selectivity, simplicity and fast response. Huan-Tsung Chang and his students from the National Taiwan University (NTU) in Taiwan had previously developed DNA-stabilized Ag/Au nanoclusters and thiol-capped Au nanodots for the sensing of H2S; but the use of expensive DNA and salt-dependent photoluminescence (PL) properties were a concern.
Advantages of aggregation
The team in NTU then prepared luminescent penicillamine (PA)-capped copper nanocluster (PA-Cu NC) aggregates from copper ions using PA as both a capping and reducing agent. The PA-Cu NCs emit light at 580 nm when excited at 326 nm through an aggregation-induced emission effect. The PL properties of PA-Cu NC aggregates show interesting polarity dependence; the emission colour can be tuned from red to yellow by varying organic solvent.
Reporting here, the as-prepared PA-Cu NCs aggregates are applied to the detection of H2S, based on analyte-induced PL quenching. Upon addition of 200 µM H2S to the aqueous solution of PA-Cu NCs aggregates, the yellow emission of PA-Cu NCs aggregates is completely quenched within 20 seconds through the formation of larger non-photoluminescent CuS nanoparticles. The PL quenching is dependent on the H2S concentration over a linear range of 1–100 µM. The PA-Cu NCs aggregates are sensitive (limit of detection is 500 nM) and selective towards H2S. This allows the detection of H2S in hot spring samples with results in agreement with that from the more conventional methylene blue method.
Although the PA-Cu NC aggregates hold great potential for environmental analysis of H2S, their use in bioanalysis is still a challenge. A method of preparing highly water soluble and highly fluorescent PA-Cu NCs aggregates is still under investigation.
Full details can be found in the journal Nanotechnology 25 195502.
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About the author
Jia-Ying Ma and Po-Cheng Chen are currently graduate students in Huan-Tsung Chang’s group at the Department of Chemistry at the National Taiwan University (NTU) in Taiwan. The main research interest of Chang’s group is green preparation of nanomaterials for bio-applications and new energy sources.