MoS₂-Based Nanoprobes for Detection of Silver Ions in Aqueous Solutions and Bacteria

Abstract

Silver as an extensively used antibacterial agent also poses potential threats to the environment and human health. Hence, in this work, we design a fluorescent nanoprobe by using rhodamine B isothiocyanate (RhoBS) adsorbed MoS2 nanosheets to realize sensitive and selective detection of Ag(+). On the surface of RhoBS-loaded MoS2 nanosheets, Ag(+) can be reduced to Ag nanoparticles, which afterward could not only lead to the detachment of RhoBS molecules and thus their recovered fluorescence but also the surface-enhanced fluorescence from RhoBS remaining adsorbed on MoS2. Such an interesting mechanism allows highly sensitive detection of Ag(+) (down to 10 nM) with great selectivity among other metal ions. Moreover, we further demonstrate that our MoS2-RhoBS complex could act as a nontoxic nanoprobe to detect Ag(+) in live bacteria samples. Our work resulted from an unexpected finding and suggests the promise of two-dimensional transition-metal sulfide nanosheets as a novel platform for chemical and biological sensing.

Photoluminescence Architectures for Disease Diagnosis: From Graphene to Thin-Layer Transition Metal Dichalcogenides and Oxides

“…The presence of Ag + induced the self‐folding of the ssDNA then weakened the binding affinity with the material platform . In contrary, a recent study using rhodamine‐MoS 2 nanosheet composites to detect Ag + proposed a different mechanism of action . It was determined that the silver ions may be rapidly reduced to silver nanoparticles in the presence of MoS 2 sheets, leading to a sharp fluorescence enhancement.…”

“…[ 69 ] In contrary, a recent study using rhodamine-MoS 2 nanosheet composites to detect Ag + proposed a different mechanism of action. [ 70 ] It was determined that the silver ions may be rapidly reduced to silver nanoparticles in the presence of MoS 2 sheets, leading to a sharp fl uorescence enhancement. This was probably due to a partial replacement of the rhodamine fl uorophores by the silver nanoparticles and a "surface-enhanced fl uorescence" mechanism by which the fl uorescence intensity of the dyes, which are retained on the MoS 2 surface, increased ( Figure 8 ).…”

Targeted fluorescence imaging enhanced by 2D materials: a comparison between 2D MoS2 and graphene oxide

“…1f) , which are the A 1g (out-ofplane vibration of S) and E 1 2g (in-plane relative motion between S and Mo) modes of hexagonal MoS 2 , respectively, suggest the formation of 2D MoS 2 . 29 In addition, the materials were also characterized using Zeta potential analysis (Fig. S1) and fluorescence spectroscopy (Fig.…”

Nanocomposites of Two-Dimensional Molybdenum and Tungsten Dichalcogenides with Metal Particles: Preparation and Prospects for Application

“…Upon further exposure, the silver NP evolve into relatively polydisperse silver nanoplatelets 420 ± 270 nm and thickness 53 ± 32 nm. The spontaneous reduction of the Ag(I) ions to the metal to give polydisperse silver NP on MoS 2 sheets coated with rhodamine B dye was also described by Yang et al [123].…”

“…Yang et al [123] have developed a selective fluorescent sensor for the determination of Ag(I) ions in biological samples containing MoS 2 sheets and supported rhodamine B dye. In the absence of analyte, the dye fluorescence is completely quenched by the semiconductor but the presence of Ag(I) ions (but not other metal ions) in solution leads to restoration of this fluorescence.…”