Mesenchymal stem cells (MSCs), due to their tumor tropism, are strongly recruited by various solid tumors and mobilized by inflammatory signals in the tumor microenvironment. However, effective cellular uptake is critical for MSC-based drug delivery. In this study, we synthesized a spherical copolymer, polyethylenimine-poly(ε-caprolactone), with aggregation-induced emission (AIE) material and the anticancer drug, paclitaxel, coloaded onto its inner core. This was followed by the addition of a transactivator of transcription (TAT) peptide, a type of cell-penetrating peptide, to modify the nanoparticles (NPs). Finally, the MSCs were employed to carry the TAT-modified AIE-NPs drug to the tumor sites and assist in simultaneous cancer diagnosis and targeted tumor therapy. In vitro, the TAT-modified AIE-NPs showed good biocompatibility, targeting, and stability in an aqueous solution besides high drug-loading and encapsulation efficiency. In vitro, the AIE-NPs exhibited a controllable release under a mildly acidic environment. The in vivo and in vitro studies showed high antitumor efficacy and low cytotoxicity of the AIE-NP drug, whereas biodistribution confirmed the tumor tropism of MSCs. To summarize, the MSC-based AIE-NP drugs loaded with TAT possessed good biocompatibility and high antitumor efficacy via the enhanced NP-drug uptake. In addition, the tumor tropism of MSCs provided selective drug uptake by the tumor cells and thus reduced the systemic side effects.

The past one hundred years have witnessed the great development of polymer science. The advancement of polymer science is closely related with the development of characterization techniques and methods, from viscometry in molecular weight determination to advanced techniques including differential scanning calorimetry, nuclear magnetic resonance, and scanning electron microscopy. However, these techniques are normally constrained to tedious sample preparation, high costs, harsh experimental conditions, or ex situ characterization. Fluorescence technology has the merits of high sensitivity and direct visualization. Contrary to conventional aggregation-causing quenching fluorophores, those dyes with aggregation-induced emission (AIE) characteristics show high emission efficiency in aggregate states. Based on the restriction of intramolecular motions for AIE properties, the AIE materials are very sensitive to the surrounding microenvironments owing to the twisted propeller-like structures and therefore offer great potential in the study of polymers. The AIE concept has been successfully used in polymer science and provides a deeper understanding on polymer structure and properties. In this review, the applications of AIEgens in polymer science for visualizing polymerization, glass transition, dissolution, crystallization, gelation, self-assembly, phase separation, cracking, and self-healing are exemplified and summarized. Lastly, the challenges and perspectives in the study of polymer science using AIEgens are addressed.

Fluorogens with aggregation-induced emission (AIEgens) have emerged as a powerful and versatile platform for the development of novel biosensors. In this study, a series of water-soluble fluorescent probes based on tetraphenylethylene (TPE) were designed and synthesized for the detection of monoamine oxidases (MAOs) based on specific interactions between the probes and the proteins. Among the six probes developed, t-TPEM displays a significant fluorescence increase upon introduction of MAOs. Of particular significance is that the fluorescence of t-TPEM in the presence of MAO-A is 21-fold higher than other proteins including MAO-B. Lineweaver-Burk plots reveal that t-TPEM acts as an uncompetitive inhibitor of MAO-A with Ki = 17.1 μM, which confirms its good binding affinity toward MAO-A. Furthermore, a cell imaging experiment reveals that t-TPEM is able to selectively monitor the activity of MAO-A which is localized in mitochondria of MCF-7 cells.