Spontaneous formation and reversible transformation between achiral J- and chiral H-aggregates of cyanine dye MTC

Two-Dimensional Supramolecular Polymorphism in Cyanine H- and J-Aggregates

We designed a new cyanine dye 1, with two pedant rod-like groups, capable of forming two distinct two-dimensional (2D) supramolecular polymorphs in methylcyclohexane; an H-type aggregate (Agg-H2) and a J-type aggregate (Agg-J). Importantly, these two polymorphs were not accessed through polymerization events, and instead through the thermal transformation of a third particle-like polymorph (Agg-H1) formed by the anti-cooperative assembly of 1. While Agg-H2 is generated upon cooling the solution of Agg-H1 by a thermoreversible polymorph transition, the Agg-J was obtained through a hidden pathway by combining sonication and cooling to the Agg-H1 solution. This is the first report on the obtention of H- and J-type cyanine polymorphs that in turn could be isolated in solid-state to render two new 2D photoactive materials. This paper unveils new strategies for designing 2D supramolecular polymers using calamitic residues, but also undercovers relevant aspects of pathway complexity and polymorph transitions that might be crucial for developing novel photonic systems.

H-Aggregation of Squaraine Dye as Generic Colorimetric Molecules to Detect Cu2

An infrared squaraine dye was utilized to detect Cu2+ in solvents based on H-aggregates of squaraine dye. H-aggregates are a type of aggregation with enhanced photophysical properties compared to monomers. In the presence of a Ca2+ solution, F-Cl offers exceptional H-aggregators that can be transformed into monomers by adding Cu2+. Furthermore, this mode successfully demonstrated fluorescence changes in HeLa cells cultured in vitro after the addition of Ca2+ or Cu2+. A highly specific detection of Cu2+ was achieved using this transformation mode.

A label-free G-quadruplex aptamer fluorescent aptasensor for visual and real-time kanamycin detection in lake and human samples

Antibiotic abuse is considered a serious problem affecting human health, necessitating that great attention be paid to explore robust, simple and sensitive methods for rapid evaluation. In this paper, we developed a fluorescent aptasensor for visual and real-time kanamycin detection by taking advantage of the label-free strategy based on H-aggregate disassembly of a chiral cyanine dye induced by a G-quadruplex aptamer. The good sensitivity and selectivity enabled this aptasensor to have a detection limit as low as 43 nM and have high specificity for kanamycin recognition. Furthermore, this assay was successfully applied for the detection of kanamycin in lake water and urine with excellent recoveries.

Metal ions-bridged J aggregation mediated nanoassembly composition for breast cancer phototherapy

Recently, the highly ordered J-aggregates of organic dyes with intriguing optical properties have received considerable attention in biomedical applications. Herein, binary metal ions Mn(II)/Fe(III) are used to induce the formation of indocyanine green (ICG) J-aggregates. Further, the sheet-like J-aggregates are able to act as "carriers" for loading hydrophobic chemotherapeutic gambogic acid (GA), realizing the effect of "killing two birds with one stone" for both treatment and delivery. The as-designed nanoassembly is formed spontaneously in aqueous environment via π-π stacking, electrostatic interaction, and hydrophobic force, exhibiting enhanced photostability of ICG and outstanding reactive oxygen species (ROS) generation ability. Moreover, significant inhibition of tumor growth by the synergetic effect of phototherapy and chemotherapy is verified in a subcutaneous 4T1 tumors model. In conclusion, this work not only presents a facile and green approach to manufacture carrier-free nanodrugs, but also establishes a universal platform that has potential application in the co-delivery of near-infrared dye and hydrophobic molecules.