General Post-Regulation Strategy of AIEgens' Photophysical Properties for Intravital Two-Photon Fluorescence Imaging.

Fluorogens with aggregation-induced emission (AIEgens) are promising agents for two-photon fluorescence (TPF) imaging. However, AIEgens' photophysical properties are fixed and unoptimizable once synthesized. Therefore, it is urgent and meaningful to explore an efficient post-regulation strategy to optimize AIEgens' photophysical properties. Herein, a general and efficient post-regulation strategy is reported. By simply tuning the ratio of inert AIEgens within binary nanoparticles (BNPs), the fluorescence quantum yield and two-photon absorption cross-section of functional AIEgens are enhanced by 8.7 and 5.4 times respectively, which are not achievable by conventional strategies, and the notorious phototoxicity is almost eliminated. The experimental results, theoretical simulation, and mechanism analysis demonstrated its feasibility and generality. The BNPs enabled deep cerebrovascular network imaging with ≈1.10 mm depth and metastatic cancer cell detection with single-cell resolution. Furthermore, the TPF imaging quality is improved by the self-supervised denoising algorithm. The proposed binary molecular post-regulation strategy opened a new avenue to efficiently boost the AIEgens' photophysical properties and consequently TPF imaging quality.

Combination of PEG-b-PAA Carrier and Efficient Cationic Photosensitizers for Photodynamic Therapy.

Photodynamic therapy (PDT) is recognized to be a promising strategy for anticancer treatment. Considering the progressive application of PDT in clinical trials, highly efficient photosensitizers (PSs) are in strong demand. Aggregation-induced emission (AIE) based PSs are promising phototheranostic materials for tumor imaging and PDT due to their high fluorescence and photosensitizing efficiency. Herein, a PS, TPA-2BCP with AIE characteristics is developed by adopting an acceptor-π-donor-π-acceptor (A-π-D-π-A) structure. However, the accumulation of ionic PSs in the tumor is poor due to non-specific interactions with bio-molecules. Therefore, we use a carboxyl-rich polymer material, polyacrylate polyethylene glycol block copolymer (PEG-b-PAA) to encapsulate the cationic PSs into nanoparticles through ionic interactions. The cationic groups are blocked and the generated PS nanoparticles can accumulate well in the tumor site in vivo. Meanwhile, the photosensitizing efficiency of the PS is further enhanced in the nanoparticle format. The tumor growth can be obviously inhibited under 530 nm laser irradiation, demonstrating its potential application in antitumor PDT.