Highly sensitive sulphide mapping in live cells by kinetic spectral analysis of single Au-Ag core-shell nanoparticles

Abstract

Hydrogen sulphide (H 2 S) is a gaseous signalling agent that has important regulatory roles in many biological systems but remains difficult to measure in living biological specimens. Here we introduce a new method for highly sensitive sulphide mapping in live cells via singleparticle plasmonic spectral imaging that uses Au-Ag core-shell nanoparticles as probes. This strategy is based on Ag 2 S formation-induced spectral shifts of the nanoprobes, which is not only highly selective towards sulphide but also shows a linear logarithmic dependence on sulphide concentrations from 0.01 nM to 10 mM. A theoretical model was established that successfully explained the experimental observations, suggesting that the local sulphide concentration as well as its oscillations can be determined indirectly from kinetic measurements of the spectral shifts of the nanoprobes. We demonstrated for the first time the realtime mapping of local variations of sulphide levels in live cells with nM sensitivity.

Optical properties of Ag–Au nanoclusters for sulphide sensing from TDDFT calculations

“…As listed in Table S1 and S2 (see the Supporting Information), it is found that the highest peaks in the plasmonic regions locate at 4.42 and 4.38 eV for the [Ag 13 ] þ and [Ag 13 S] þ clusters, respectively. It means that the plasmonic region of the [Ag 13 S] þ cluster is less intense than that of the [Ag 13 ] þ one, indicating the redshifts of the vertical excitation spectrum of the [Ag 13 S] þ cluster compared with the [Ag 13 ] þ one, which agrees very well with the experimental results [7]. The redshift is caused by the difference of refractive index between the cationic Ag 13 S and Ag 13 clusters according to the classical Mie theory [10,11,38], where wavelength shift Dl is proportional to the change in refractive index Dn.…”

“…Moreover, the spectrum of the [Ag 12 AuS 3 ] þ cluster redshifts around 0.5 eV and turn to be considerably weaker compared with the [Ag 12 AuS] þ one. It can be concluded that increasing the coverage of sulphides leads to more redshifts and weaker oscillator strengths, which agrees well with the previous experimental results [7].…”

“…However, these sensors are mostly based on the irreversible reactions and thus cannot be utilized to monitor the time-dependent continuous fluctuation in sulphide concentration inside the live cells, especially at the singlemolecule level. More recently, Xiong et al [7] developed highly sensitive sulphide probes by using AgeAu plasmonic nanoparticles (NPs), which are much more effective than the reported metal oxides and sulphide-responsive fluorescent probes. However, the sensing mechanism for detecting sulphide using AgeAu NPs is still unclear.…”

Collective motion of bacteria and their dynamic assembly behavior

“…So far people have been using micron-sized passive particles to trace the hydrodynamics of the bacterial environment. During the past decade, our research group have developed a series of nano-imaging techniques capable of tracing single plasmonic nanoparticles with high sensitivity and high resolution [66][67][68][69][70][71]. Inspired by single particle tracing at the micron-scale, it is expected that a lot of new information on the collective motion of bacteria could be obtained by tracking the spatial and temporal variation of multiple single nanoparticle tracers at the nanoscale.…”

Silver/Gold Core–Shell Nanoprism‐Based Plasmonic Nanoprobes for Highly Sensitive and Selective Detection of Hydrogen Sulfide

“…[10] Recently, a plamonic probe was developed for sulfide mapping in living cells using gold/silver core-shell nanoparticles. [11] Though promising, this nanoprobe showed low selectivity toward hydrogen sulfide because some species can also etch the silver on the outer surface of the gold/silver core-shell nanoprobes, resulting in false signals. Therefore, it remains a challenge to develop new plasmonic probes with high sensitivity and selectivity.…”