Recent trends in molecular aggregates: An exploration of biomedicine

Abstract

Molecular aggregates are receiving tremendous attention, demonstrating immense potential for biomedical applications in vitro and in vivo. For instance, the molecular aggregates of conventional fluorophores influence the electronic excitation states of the aggregates, causing characteristic photophysical property changes. A fundamental understanding of this classical relationship between molecular aggregate structures and photophysics has allowed for innovative biological applications. The chemical characteristics of drug molecules generally trigger the formation of colloidal aggregates, and this is considered detrimental to the drug discovery process. Furthermore, nano-sized supramolecular aggregates have been used in biomedical imaging and therapy owing to their optimal properties for in vivo utility, including enhanced cell permeability, passive tumor targeting, and convenient surface engineering. Herein, we provide an overview of the recent trends in molecular aggregates for biomedical applications. The changes in photophysical properties of conventional fluorophores and their biological applications are discussed, followed by the effects of conventional drug molecule-aggregates on drug discovery and therapeutics development. Recent trends in the investigation of biologically important analytes with aggregation-induced emission are discussed for conventional and unconventional fluorophores. Lastly, we discuss nano-sized supramolecular aggregates used in imaging and therapeutic purposes, with a focus on in vivo utilization.

Aggregation-Induced Emission Nanoparticles for Single Near-Infrared Light-Triggered Photodynamic and Photothermal Antibacterial Therapy

“…The synthetic procedures for AIE NPs are illustrated in Figure A, and the structures and characterization results of AIEgen (molecule 12 ) are shown in Figures S1–S7 (Supporting Information). The key molecular design strategy of the present NIR-II AIEgen is the incorporation of a positively charged group into the highly twisted compound 11 with a highly twisted architecture, which provides not only AIE properties but also ROS generation ability. , To improve the understanding of the molecular properties of the synthesized AIE, density functional theory was employed to calculate the electron cloud on the frontier molecular orbital. The electron clouds of the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) of isoquinolinium–coumarin (IQ-Cm) were fully separated (Figure B).…”

Spectroscopic and theoretical insights into hydrogen bonding clusters, triplet species, and the relaxation mechanism of the light (1ππ*) excited state of 4-methyl-1,2,4-triazole-3-thione

“…In this regard, recent developments have been extended to biomedical applications, photodynamic therapy, etc. 64–68…”

Pyrene-Based AIE Active Materials for Bioimaging and Theranostics Applications

“…For instance, interactions between water and weakly emissive molecules led to the formation of a highly emissive aggregation state via H-bonding [ 52 ]. During AIEE, the pyrene derivatives underwent excimer formation, which led to structures of feasible H - or J -type aggregate [ 53 , 54 , 55 , 56 , 57 , 58 ]. By definition, molecules stacked in a predominantly face-to-face arrangement is called H -aggregation.…”