Triarylboron-Based High Photosensitive Probes for Apoptosis Detection, Tumor-Targeted Imaging, and Selectively Inducing Apoptosis of Tumor Cells by Photodynamics

CB[8]- and triarylboron-based supramolecular organic framework for microRNA detection, tumor-targeted drug delivery, and photodynamic therapy

Supramolecular organic frameworks (SOFs) are widely used for biological detection and drug delivery. In this study, a SOF system was fabricated through the self-assembly of photosensitive triarylboron (TAB), TAB-6-methyl, and CB[8]. The maximum fluorescence emission of TAB-6-methyl was greatly enhanced and red-shifted from 560 nm to 610 nm after SOF formation. The SOF can specifically respond to a microRNA by dissembling and then combining with microRNA, which is accompanied by a fluorescence shift from 610 nm to 560 nm, thus providing a ratiometric readout for microRNA detection. The photosensitivity of TAB-6-methyl can be further improved by forming a SOF, which can be used in photodynamic therapy. By constructing another guest molecule, TAB-5-1-cRGD, we successfully embedded cRGD in the SOF system to improve its tumor-targeting ability. Moreover, we used this SOF system as a fluorescence imaging probe for targeted tumor imaging and as a drug carrier system for loading DOX to achieve combined photodynamic and chemotherapy treatment of tumors.

POSS engineering of squaraine nanoparticle with high photothermal conversion efficiency for photothermal therapy

Photothermal therapy (PTT) has been extensively studied due to its promising therapeutic effects and potential for development in cancer treatments. Central to PTT is the development of photothermal agents (PTAs). This study presents a novel nanoparticle called POSS-SQ, which satisfies the necessary conditions to function as a PTA. Comprised of squaraine (SQ) and polyhedral oligomeric sesquisiloxane (POSS), POSS-SQ NPs exhibit strong near-infrared (NIR) absorption and high photothermal conversion efficiency (PCE) attributable to the intermolecular electron transfer in SQ. Furthermore, POSS when modified with polyethylene glycol (PEG) through "click" chemistry, effectively enhances cell permeability and biocompatibility of the nanoparticles. Photothermal experiments reveal that POSS-SQ NPs demonstrate concentration and laser power dependence, with a PCE of 67.2%. In vitro and in vivo experiments confirm the excellent biosafety and tumor growth inhibition potential of POSS-SQ NPs under laser irradiation, attributed to the synergistic effects of enhanced cell permeability and exceptional photothermal properties. This research highlights the possibility of obtaining PTAs with high PCE and excellent biocompatibility by combining SQ-N and POSS, offering a new approach for designing and developing more efficient PTAs to enhance better PTT outcomes.

Immuno-photodynamic Therapy (IPDT): Organic Photosensitizers and Their Application in Cancer Ablation

Photosensitizer-based photodynamic therapy (PDT) has been considered as a promising modality for fighting diverse types of cancers. PDT directly inhibits local tumors by a minimally invasive strategy, but it seems to be incapable of achieving complete eradication and fails to prevent metastasis and recurrence. Recently, increasing events proved that PDT was associated with immunotherapy by triggering immunogenic cell death (ICD). Upon a specific wavelength of light irradiation, the photosensitizers will turn the surrounding oxygen molecules into cytotoxic reactive oxygen species (ROS) for killing the cancer cells. Simultaneously, the dying tumor cells release tumor-associated antigens, which could improve immunogenicity to activate immune cells. However, the progressively enhanced immunity is typically limited by the intrinsic immunosuppressive tumor microenvironment (TME). To overcome this obstacle, immuno-photodynamic therapy (IPDT) has come to be one of the most beneficial strategies, which takes advantage of PDT to stimulate the immune response and unite immunotherapy for inducing immune-OFF tumors to immune-ON ones, to achieve systemic immune response and prevent cancer recurrence. In this Perspective, we provide a review of recent advances in organic photosensitizer-based IPDT. The general process of immune responses triggered by photosensitizers (PSs) and how to enhance the antitumor immune pathway by modifying the chemical structure or conjugating with a targeting component was discussed. In addition, future perspectives and challenges associated with IPDT strategies are also discussed. We hope this Perspective could inspire more innovative ideas and provide executable strategies for future developments in the war against cancer.

Multicolor Adjustable B-N Molecular Switches: Simple, Efficient, Portable, and Visual Identification of Butanol Isomers

As intelligent probes, dynamic and controllable molecular switches are useful tools for probing and intervening in life processes. However, the types and properties of molecular switches are still relatively single and often can only make two actions: "off" and "on". Therefore, the development of novel molecular switches with multiple colors and multiple instructions is very challenging. Herein, we propose a novel strategy based on the instability of the Lewis acid-base pair (boron (B) and nitrogen (N)), such as introducing the Schiff base (C═N) group into the aminoborane skeleton and preparing the novel molecular switches BN-HDZ and BN-HDZ-N. These two molecules were found to have good multicolor fluorescence switching capability for methanol. Surprisingly, the compound BN-HDZ-N shows unprecedented visual identification for the butanol isomers and could be made into a portable strip for simple and rapid visual identification of the four isomers of butanol, promising an alternative to conventional Lucas reagents. This provides a novel strategy for the design and fabrication of novel multicolor-tunable molecular switches with visual identification of isomers.