Plasmonically Coupled Nanoreactors for NIR-Light-Mediated Remote Stimulation of Catalysis in Living Cells

Abstract

Artificial nanoreactors that can facilitate catalysis in living systems on-demand with the aid of a remotely operable and biocompatible energy source are needed to leverage the chemical diversity and expediency of advanced chemical synthesis in biology and medicine. Here, we designed and synthesized plasmonically integrated nanoreactors (PINERs) with highly tunable structure and NIR-light-induced synergistic function for efficiently promoting unnatural catalytic reactions inside living cells. We devised a synthetic approach toward PINERs by investigating the crucial role of metal-tannin coordination polymer nanofilmthe pH-induced decomplexation-mediated phase-transition processfor growing arrays of Au-nanospheroid-units, constructing a plasmonic corona around the proximal and reactant-accessible silica-compartmentalized catalytic nanospace. Owing to the extensive plasmonic coupling effect, PINERs show strong and tunable optical absorption in the visible to NIR range, ultrabright plasmonic light scattering, controllable thermoplasmonic effect, and remarkable catalysis; and, upon internalization by living cells, PINERs are highly biocompatible and demonstrate dark-field microscpy-based bioimaging features. Empowered with the synergy between plasmonic and catalytic effects and reactant/product transport, facilitated by the NIR-irradiation, PINERs can perform intracellular catalytic reactions with dramatically accelerated rates and efficiently synthesize chemically activated fluorescence-probes inside living cells.

Nanocatalosomes as Plasmonic Bilayer Shells with Interlayer Catalytic Nanospaces for Solar‐Light‐Induced Reactions

“…10 nm thickness) modified with Au‐seeds ( AuNC@ h ‐SiO 2 ) and coated with a thin conformal film (ca. 3 nm) of TA‐Fe coordination polymer using a modified reported chemistry (Figure S1) . Next, the TA‐Fe‐coated AuNC@ h ‐SiO 2 were dispersed in aqueous solution of PVP (1 mL, 2 %) followed by the addition of HAuCl 4 (900 μL, 5 m m ) and hydroquinone (900 μL, 50 m m ) leading to the growth of Au‐seeds in the homogeneously larger and closely spaced AuNP‐units, simultaneously on the outer and inner surfaces of h ‐SiO 2 ‐template (Figure a and Figure S2 in the Supporting Information), resulting in Au‐bilayer structures of NCat , designated as Au‐1‐NCat , Au‐2‐NCat , Au‐3‐NCat , and Au‐4‐NCat , [collectively represented as Au‐1–4‐NCat ] prepared from the increasing amounts (0.38, 0.6, 0.75 and 0.9 mL) of 5 m m HAuCl 4 (Figure S2 and Figure a).…”

“…As shown in the transmission electron microscopy (TEM) image of Au‐4‐NCat (Figure a), the outer Au‐layer grew slightly thicker (14±1 nm) than the inner Au‐layer (11±1 nm), forming a structure collectively evolving as a hollow concentric metallic bilayer configuration, where each Au‐layer is composed of arrays of closely spaced AuNP‐units; and the interlayer space comprises massive number of few‐nm cavities confined by AuNPs, which remain accessible through the narrow interparticle channels among the non‐coalesced AuNP‐units. In the plausible Au‐growth mechanism, the TA‐Fe nanofilm deassembles in the presence of HAuCl 4 , due to the pH‐dependent reversible Fe III ‐TA co‐ordination chemistry and generates TA‐oligomers having plenty of free catecholic moieties on the surface of AuNC@ h ‐SiO 2 ; followed by the directed approach of Au 3+ towards the outer and inner Au‐seeds permeating through the microporous aminosilica‐layer (Figure a) . Replacing hydroquinone with other reducing agents did not result the desired Au‐bilayer structure (Figure S3).…”

“…For example, plasmonic metal‐based nanostructures with controllable few‐nm ultra‐narrow gaps, junctions, and cavities, can dramatically augment the broad optical extinction and generate electromagnetic fields that are many orders of magnitude higher than those found for the isolated nanoparticle (NP) units. These increases originate from collective excitation and extensive multimodal plasmonic coupling; these nanoscale effects in turn result efficient generation of energetic charge carriers and localized increase in photothermal temperatures, highly advantageous in promoting interfacial catalytic reactions . So far, it is elusive to achieve such controllable structural intricacy at few‐nm scale in a single nanostructure, which would provide a massive density of confined cavities for highly efficient plasmon‐induced catalysis.…”

Transition Metal‐Promoted Reactions in Aqueous Media and Biological Settings

“…Cho and Lee have shown that by using plasmonically integrated nanoreactors with strong and tunable IR absorption in the visible to NIR, they can dramatically accelerate intracellular depropargylationr eactions. [129] In arecent article, Brikand co-workersdemonstrated the viability of uncaging propargylated peptides under mild aqueous conditions, using AuCl. [130a] The methodm ight be applicable in biological environments.…”

“…Cho and Lee have shown that by using plasmonically integrated nanoreactors with strong and tunable IR absorption in the visible to NIR, they can dramatically accelerate intracellular depropargylation reactions [129] …”