AIE-active macromolecules: designs, performances, and applications

Aggregation-induced emission (AIE) macromolecules as emerging luminescent materials gained increasing attention owing to their good processability, high brightness, wide functionality, and smart responsiveness, with great potential in many fields.

Dynamic Photochromic Polymer Nanoparticles Based on Matrix-Dependent Förster Resonance Energy Transfer and Aggregation-Induced Emission Properties

Dynamic color-tunable fluorescent materials are sought-after materials in many applications. Here, we report a polymeric matrix-regulated fluorescence strategy via synergistically modulating aggregation-induced emission (AIE) properties and the Förster resonance energy transfer (FRET) process, which leads to tunable dynamic variation of color and photoluminescence (PL) intensity of fluorescent polymeric nanoparticles (FRET-PNPs) driven by photoirradiation. The FRET-PNPs were prepared via a facile one-pot miniemulsion copolymerization with the tetraphenyletheyl (TPE) and spiropyran (SP) units chemically bonded to the polymer matrix. The FRET-PNPs exhibited dynamic variation of fluorescence properties (colors and PL intensity) under photoirradiation on the timescale of minutes. The variation of the polymer matrix composition could deliberately influence the AIE property of TPE units and the isomerization process of SP to merocyanine units, which further affect the FRET efficiency of FRET-PNPs and, eventually, lead to versatile dynamic fluorescence variation. The dynamic fluorescence property as well as the excellent processability and film formation ability of FRET-PNPs allowed for diverse applications, such as warning labels, dynamic decorative painting, and multiple information encryption. Without sophisticated molecular design or tedious preparation processes, a new perspective for the design, fabrication, and performance optimization of fluorescent nanomaterials for innovative applications was proposed.

Light and latex: advances in the photochemistry of polymer colloids

Unparalleled temporal and spatial control of colloidal chemical processes introduces immense potential for the manufacturing, modification, and manipulation of latex particles.

Facile Incorporation of "Aggregation-Induced Emission"-Active Conjugated Polymer into Mesoporous Silica Hollow Nanospheres: Synthesis, Characterization, Photophysical Studies, and Application in Bioimaging

Typical aggregation-induced emission (AIE) luminogens tetraphenylethylene (TPE) and triphenylamine have been used to construct an AIE-active conjugated polymer, namely, poly(N,N-diphenyl-4-(4-(1,2,2-triphenylvinyl)styryl)aniline) (PTPA), which consist of D-π-A architecture by Wittig polymerization. We fabricated mesoporous silica hollow nanospheres (MSHNs) which were encapsulated with the AIE-active polymer for applications in cellular imaging. It exhibits a positive solvatochromism effect by increasing solvent polarity, supported by theoretical calculation using density functional theory. The structure of the monomers and polymer was confirmed by Fourier transform infrared, nuclear magnetic resonance, and high-resolution mass spectrometry techniques. Considering the advantage of high brightness in the fluorescence of PTPA, it was encapsulated into MSHNs by a noncovalent approach, and the surface was functionalized with an anti-EpCAM (antiepithelial cell adhesion molecule) aptamer through conjugation with γ-glycidoxypropyltrimethoxysilane for targeting cancer cells specifically. The aptamer-functionalized Apt-MSHNs exhibited excellent biocompatibility with the liver cancer-Huh-7 cells used for this study and was efficiently internalized by these cells. Because EpCAM are overexpressed in multiple carcinomas, including liver cancer, these aptamer-conjugated AIE MSHNs are therefore good candidates for targeted cellular imaging applications.

Fluorescent Imidazolium-Type Poly(ionic liquid)s for Bacterial Imaging and Biofilm Inhibition

Fluorescent imidazolium-type poly(ionic liquid)s (PIL)s were synthesized by anion exchange of bromide (Br^-) in poly(3-butyl-1-vinylimidazolium bromide) (PIL-Br) with a fluorescent anion, namely, 3-(4-(1,2,2-triphenylvinyl)phenoxy)propane-1-sulfonate (TPESO₃^-). Such an anion exchange provided antibacterial PILs with aggregation-induced emission (AIE) properties that simultaneously kill and image bacteria. These fluorescence and antibacterial properties could be regulated by controlling the Br^-/TPESO₃^- ratio. The fluorescence intensity increases as this ratio increases, while the antibacterial property exhibits an opposite trend. Moreover, the AIE-type PILs are useful for fluorescently imaging dead bacteria (macroscopically and microscopically) and could effectively inhibit biofilm growth. This study provided a convenient method to obtain fluorescent PILs with adjustable antibacterial and imaging properties.

Cell-penetrating peptide modified AIE polymeric nanoparticles by miniemulsion polymerization and application for cell fluorescence imaging

AIE polymeric nanoparticles surface-modified with HIV Tat peptides for cell fluorescence imaging are efficiently prepared through miniemulsion polymerization, carbodiimide reaction, and thiol-maleimide click reaction in sequence.

Progress and Trends in AIE-Based Bioprobes: A Brief Overview

Luminescent bioprobes are powerful analytical means for biosensing and optical imaging. Luminogens featured with aggregation-induced emission (AIE) attributes have emerged as ideal building blocks for high-performance bioprobes. Bioprobes constructed with AIE luminogens have been identified to be a novel class of FL light-up probing tools. In contrast to conventional bioprobes based on the luminophores with aggregation-caused quenching (ACQ) effect, the AIE-based bioprobes enjoy diverse superiorities, such as lower background, higher signal-to-noise ratio and sensitivity, better accuracy, and more outstanding resistance to photobleaching. AIE-based bioprobes have been tailored for a vast variety of purposes ranging from biospecies sensing to bioimaging to theranostics (i.e., image-guided therapies). In this review, recent five years' advances in AIE-based bioprobes are briefly overviewed in a perspective distinct from other reviews, focusing on the most appealing trends and progresses in this flourishing research field. There are altogether 11 trends outlined, which have been classified into four aspects: the probe composition and form (bioconjugtes, nanoprobes), the output signal of probe (far-red/near-infrared luminescence, two/three-photon excited fluorescence, phosphorescence), the modality and functionality of probing system (dual-modality, dual/multifunctionality), the probing object and application outlet (specific organelles, cancer cells, bacteria, real samples). Typical examples of each trend are presented and specifically demonstrated. Some important prospects and challenges are pointed out as well in the hope of intriguing more interests from researchers working in diverse areas into this exciting research field.

Marrying multicomponent reactions and aggregation-induced emission (AIE): new directions for fluorescent nanoprobes

Recent development and progress for fabrication and applications of aggregation-induced emission polymers through multicomponent reactions have been summarized in this review.