A Novel Three-Dimensional Nanosensing Array for the Discrimination of Sulfur-Containing Species and Sulfur Bacteria

The discrimination of various sulfur -containing species helps us to deeply understand how sulfur affects cellular signaling and other physiological events. Herein, we present a three-dimensional sensor array based on simultaneous variation of the optical properties (fluorescence, light scattering, and UV-vis absorption) of gold-silver alloy nanocluster (AuAgNCs)-gold nanoparticle (AuNPs) composite for the rapid identification of 13 sulfur-containing species and sulfur-oxidizing bacteria. The sensor array is fabricated based on the strong coordination interactions between sulfur-containing compounds and AuAgNCs on the surface of AuNPs. The sulfur species of interest exhibit different affinities toward AuAgNCs and generate unique optical properties. These response patterns could divide the analytes into three categories including organic sulfide, inorganic sulfide, and thiols. Thirteen types of sulfur species including cystine, methionine, GSSG, S^2-, SO₃^2-, S₂O₃^2-, S₂O₇^2-, S₂O₈^2-, S₄O₆^2-, GSH, N-acetyl-l-cysteine, homocysteine, and cysteine can be well distinguished by the sensor array with principal component analysis at 0.5 μM. Moreover, sulfur-oxidizing bacteria and nonsulfur bacteria can also be well discriminated at a level of OD₆₀₀ = 0.005.