RESUMEN
Plasmonic metal/semiconductor nanohybrids hold great promise in photocatalysis and biosensor development; however, their potential phototherapeutic applications are yet fully unexplored. On the other hand, the demand of high laser power density to induce antibacterial photothermal therapeutic effects greatly restricts the practical applicability of the previously developed photothermal nanoagents (PTAs) for anticancer photothermal therapy (PTT). Here, we develop a plasmonic nanohybrid by integrating plasmonic noble metal gold nanorods (AuNRs) with a two-dimensional graphene oxide (2-D GO), capable to perform photothermal ablation of both bacterial pathogens as well as tumor cells, respectively, under low power single near-infrared (NIR) laser activation. Owing to the synergistic plasmonic photothermal effect (PPTT) of dual plasmonic PTAs, the plasmonic AuNR/GO nanohybrid exhibits remarkably higher photothermal conversion efficiency (PCE, 72.59%) than either individual AuNRs or GO under low laser power density (300 mW), leading to enhanced antibacterial/anticancer PTT. In addition, the synergistic plasmonic antibacterial/anticancer PTT induced by the plasmonic nanohybrid is also far superior to individual PTAs (AuNRs or GO), whereas the flow cytometric analysis of heat shock proteins (HSP 70) clearly dictates that the substantial killing of bacterial pathogens/tumor cells is solely due to the synergistic PPTT. Thus, the plasmonic AuNR/GO nanohybrid is a standalone PTA to perform simultaneous antibacterial/anticancer PTT under low power NIR laser activation for only 5 min, without any systemic side effects. The present study provides a clear demonstration about the potential therapeutic impact of plasmonic nanohybrids and thus will surely pave the way to design other hybrid nanoagents with enhanced PCE and integrate them with chemotherapeutic agents, leading to dual-modal chemo-/photothermal antibacterial/anticancer therapy under low power single laser excitation for a short duration.
RESUMEN
Hydrogen sulfide (H2S) has been recognized as an important endogenous gasotransmitter associated with biological signaling transduction. However, recent biological studies implied that the H2S-related cellular signaling might actually be mediated by hydrogen polysulfides (H2S n , n > 1), not H2S itself. Unraveling such a mystery strongly demanded the quantification of endogenous H2S n in living systems. However, endogenous H2S n has been undetectable thus far, due to its extremely low concentration within cells. Herein, we demonstrated a strategy to detect ultra-trace endogenous H2S nvia a fluorescent τ-probe, through changes of fluorescence lifetime instead of fluorescence intensity. This τ-probe exhibited an ultrasensitive response to H2S n , bringing about the lowest value of the detection limit (2 nM) and a lower limit of quantification (10 nM) to date. With such merits, we quantified and mapped endogenous H2S n within cells and zebrafish. The quantitative information about endogenous H2S n in cells and in vivo may have a significant implication for future research on the role of H2S n in biology. The methodology of the τ-probe established here might provide a general insight into the design and application of any fluorescent probes, beyond the limit of utilizing fluorescence intensity.