Nano-Assemblies from J-Aggregated Dyes: A Stimuli-Responsive Tool Applicable To Living Systems

Abstract

Controlling the packing arrangements of dyes is a facile way of tuning their photophysical and/or photochemical properties, thus enabling new sensing mechanisms for photofunctional tools. Here, we present a general and robust strategy toward water-stable J-aggregated dye-templated nanoassemblies by incorporating an amphiphilic diblock copolymer and a stimuli-responsive dye as the only two building components. An iodo-substituted boron dipyrromethene (BODIPY) was adopted as a template to direct the self-assembly of poly(ethylene glycol)-block-polycaprolactone (PEG−PCL), forming a core−shell nanoplate with slip-stacked BODIPYs as core surrounded by hydrophilic PEG shell. The self-assembled nanoplate is stable in cell culture medium and possesses a built-in stimuli-responsiveness that arises from BODIPY bearing meso-carboxylate protecting group, which is efficiently removed upon treatment with peroxynitrite. The resulting negative charges lead to rearrangement of dyes from J-stacking to nonstacking, which activates photoinduced singlet oxygen production from the nanoassemblies. The stimuli-activatable photosensitivity has been exploited for specific photodynamic ablation of activated RAW 264.7 cells with excessive endogenous peroxynitrite. In light of the generality of the sensing mechanism, the concept described herein will significantly expand the palette of design principles to develop diverse photofunctional tools for biological research and clinical needs.

Two Orthogonal Halogen‐Bonding Interactions Directed 2D Crystalline Supramolecular J‐Dimer Lamellae

“…For Br⋅⋅⋅π bond, the distance of bromine atom to the centroid of BODIPY core, d Br⋅⋅⋅π , is 3.753 Å, and the angle φ is 96.85° (Figure b), and those for Cl⋅⋅⋅π bond are 3.756 Å and 99.00° (Figure d), respectively, within the criteria for X⋅⋅⋅π interactions . Notably, π‐stacking interaction also existed in the BODIPY J‐dimer as in other reported BODIPY J‐aggregates . Collectively, the halogenated BODIPY dimerized in an antiparallel manner on the formation of a π–π bond and dual X⋅⋅⋅π halogen bonds as shown in Figure b, d and also illustrated in Figure c.…”

“…Two halogenated BODIPY dyes, that is, BDP‐Cl and BDP‐Br , and a halogen‐free analogue, BDP‐H , were synthesized according to the procedures as shown in Scheme S1 (see the Supporting Information). In organic solvent, such as acetone, the three BODIPYs were dissolved in the monomer form, which was reflected by the typical monomer absorption band (Figures a, c, and S1a) . Upon adding water to the acetone solution of BDP‐Cl or BDP‐Br to a critical water fraction of 70 or 60 %, a red‐shifted absorption band emerged at about 786 nm, suggesting J‐aggregation of BODIPYs (Figures a, c, S2a, and S3a) .…”

“…In organic solvent, such as acetone, the three BODIPYs were dissolved in the monomer form, which was reflected by the typical monomer absorption band (Figures a, c, and S1a) . Upon adding water to the acetone solution of BDP‐Cl or BDP‐Br to a critical water fraction of 70 or 60 %, a red‐shifted absorption band emerged at about 786 nm, suggesting J‐aggregation of BODIPYs (Figures a, c, S2a, and S3a) . By contrast, no J‐band was observed for BDP‐H in the water/acetone mixture with water fraction increasing to 60 %, beyond which precipitates formed (Figure S1, Supporting Information).…”

Universal Scaffold for an Activatable Photosensitizer with Completely Inhibited Photosensitivity

“…As illustrated in Scheme , azide‐functionalized PS Se‐I ( azide PS Se‐I ) was synthesized. The flexibility of the click chemistry and phenolic hydroxy protecting‐group chemistry enabled us to prepare a triphenylphosphonium cation (TPP; mitochondria‐targeting group) functionalized aPS ( mito‐PN PS ) containing peroxynitrite‐responsive arylboronate as the triggerable moiety (Scheme ; see the Supporting Information). mito‐PN PS was very stable in PBS (see Figure S23), and was instantly converted into mito PS in the presence of OONO − (Scheme ), as evidenced by a recovery of the visible absorption of mito PS (Figure a; see Figure S24).…”

Recent Advances on Stimuli‐Responsive Smart Materials and their Applications

“…Thus, the design of BODIPY based aggregates important for clinical research, photodynamic therapy and biomedical applications ( Figure 23). [94] Huang et al, reported the quick response of selenoxide portray under oxidising/reducing agents induces the amphiphilicity property and further reduced to selenide moiety by vitamin C. Selenium/pillar [5]arene exhibits vesicles in water and noncyclic monomer/pillar [5]arene formed micelles, however, both morphology were destroyed on addition of vitamin C. Later, micelles and vesicles regenerated with H 2 O 2 indicates the possibility of reversible self-assembly employed in targeted drug delivery of doxorubicin (DOX). [95] Another report suggested that the redox responsive property from host/guest complex- ation of selenium/pillar [6]arene/ferrocenium wherein ferrocene played vital role.…”