Aggregation-induced emission-active micelles: synthesis, characterization, and applications

Aggregation-induced emission (AIE)-active micelles are a type of fluorescent functional materials that exhibit enhanced emissions in the aggregated surfactant state. They have received significant interest due to their excellent fluorescence efficiency in the aggregated state, remarkable processability, and solubility. AIE-active micelles can be designed through the self-assembly of amphipathic AIE luminogens (AIEgens) and the encapsulation of non-emissive amphipathic molecules in AIEgens. Currently, a wide range of AIE-active micelles have been constructed, with a significant increase in research interest in this area. A series of advanced techniques has been used to characterize AIE-active micelles, such as cryogenic-electron microscopy (Cryo-EM) and confocal laser scanning microscopy (CLSM). This review provides an overview of the synthesis, characterization, and applications of AIE-active micelles, especially their applications in cell and in vivo imaging, biological and organic compound sensors, anticancer drugs, gene delivery, chemotherapy, photodynamic therapy, and photocatalytic reactions, with a focus on the most recent developments. Based on the synergistic effect of micelles and AIE, it is anticipated that this review will guide the development of innovative and fascinating AIE-active micelle materials with exciting architectures and functions in the future.

Biobased dynamic hydrogels by reversible imine bonding for controlled release of thymopentin

Thymopentin (TP5) is widely used in the treatment of autoimmune diseases, but the short in vivo half-life of TP5 strongly restricts its clinical applications. A series of blank and TP5 loaded hydrogels were synthesized via reversible dual imine bonding by mixing water soluble O-carboxymethyl chitosan (CMCS) with a dynamer (Dy) prepared from Jeffamine and benzene-1,3,5-tricarbaldehyde. TP5 release from hydrogels was studied at 37 °C under in vitro conditions. The molar mass of CMCS, drug loading conditions and drug content were varied to elucidate their effects on hydrogel properties and drug release behaviors. Density functional theory was applied to theoretically confirm the chemical connections between TP5 or CMCS with Dy. All hydrogels exhibited interpenetrating porous architecture with average pore size from 59 to 83 μm, and pH-sensitive swelling up to 10,000% at pH 8. TP5 encapsulation affected the rheological properties of hydrogels as TP5 was partially attached to the network via imine bonding. Higher TP5 loading led to higher release rates. Faster release was observed at pH 5.5 than at pH 7.4 due to lower stability of imine bonds in acidic media. Fitting of release data using Higuchi model showed that initial TP5 release was essentially diffusion controlled. All these findings proved that the dynamic hydrogels are promising carriers for controlled delivery of hydrophilic drugs, and shed new light on the design of drug release systems by both physical mixing and reversible covalent bonding.

100th Anniversary of Macromolecular Science Viewpoint: Poly(N-isopropylacrylamide)-Based Thermally Responsive Micelles

Poly(N-isopropylacrylamide) (PNIPAAm)-based thermally responsive micelles are of great importance as smart materials for a number of applications such as drug delivery and biosensing, owing to their tunable lower critical solution temperature (LCST). Their design and synthesis in the nanoscale size range have been widely studied, and research interest in their structural and physic-chemical properties is continually growing. In this Viewpoint, representative research on the construction of PNIPAAm-based thermally responsive micelles as well as their applications are highlighted and discussed, which would serve as a good start for newcomers in this field and a positive guide for future research.

Molecular balloon, Pd6L8 cages: recognition of alkyl sulfate surfactants

Significant structural contraction and expansion of flexible Pd₆L₈ cages by encapsulation of alkyl sulfate were demonstrated. The contact angles on the fine-ground microcrystal layers shift according to the chain length of the alkyl sulfate.