Host-Guest Photosensitizer of a Cationic BODIPY Derivative and Cucurbit[7]uril for High-Efficiency Visible Light-Induced Photooxidation Reactions

Epitope molecularly imprinted polymers based on host-guest interaction: specific recognition of CD59

The detection of CD59 is of great clinical importance since it is an important glycoprotein that can serve as a biomarker related to kinds of cancers. In this work, we prepared host-guest interaction based oriented epitope molecularly imprinted polymer (hg-EMIP) for the immobilization of CD59 N-terminal epitopes. Cucurbit[7]uril (CB[7]) and l-phenylalanine (L-phe) were employed as the host and guest; and tannic acid (TA) with abundant hydroxyl groups and diethylenetriamine (DETA) were chosen as the functional monomer and crosslinking agent, respectively. The obtained hg-EMIP can specifically recognize CD59 with the adsorption capacity of 88.2 mg/g and imprinting factor of 5.63, and possesses high reusability. The hg-EMIP-based method possesses a wide linear range (1 ng/mL - 1 μg/mL) and low limit of detection (0.44 ng/mL), and can be successfully used for the detection of CD59 in human serum sample. This study provides a scheme for the preparation of host-guest based epitope molecularly imprinted polymers for helping to identify potential disease biomarkers efficiently.

Tracking host-guest recognition in cells by a BODIPY·CB[7] complex

Interested in host·guest binding events in cellular environments, intracellular recognition between fluorescent BODIPY+ and cucurbit[7]uril was explored for lysosome tracking in living cancer cells. Sequential deaggregation from spontaneously dimerized BODIPY+ was unusually discovered upon complexation with CB[7].

Integrating Two Photochromics into One Three-Dimensional Covalent Organic Framework for Synergistically Enhancing Multiple Photocatalytic Oxidations

While photocatalytic oxidations are a category of important reactions in wide chemical synthesis, the fabrication of effective photocatalysts for broad oxidation reactions is still of a great challenge. Herein, by rationally integrating two photochromics, porphyrin and triphenylamine, a three-dimensional photoactive covalent organic framework (COF) is successfully constructed for photocatalytic oxidations. Characterization studies not only show the formation of a crystalline and three-dimensional porous framework, but also reveal its effective photochemical semiconductor properties derived from the porphyrin and triphenylamine moieties. Electron paramagnetic resonance measurements indicate that the COF is an effective photocatalyst for the generation of both singlet oxygen (1O2) and superoxide radical anions (⋅O2 -). Synergistically enhanced efficiency in all photocatalytic reactions of photocatalytic aerobic oxidation of alkylbenzenes and silanes as well as thioanisoles, and cross-dehydrogenative coupling reaction of N-phenyltetrahydroisoquinoline and indole is confirmed by both experimental and theoretical studies, demonstrating its promising potential for broad photocatalytic oxidation reactions.

Photostable Mn(II) Complex of Curcumin for Effective Photodynamic Therapy and Precise Three-Dimensional In Vivo Tumor Imaging

Photoactive complexes of first-row transition metals with emission properties offer a dual approach to cancer treatment, enabling precise optical tumor detection and subsequent eradication using light. We report a photostable and photoactive mixed-ligand Mn(II) complex, Mn4, featuring a naturally occurring curcumin ligand and dipyridophenazine base. Mn4 demonstrates significant visible and red light-triggered phototoxicity against cancer cells and precise tumor imaging capability in vivo. The complex exhibits an absorption band in the visible region, extending its tail into the red region, and shows excellent dark and photostability in solution. Mn4 induces significant phototoxicity against HeLa (cervical), A549 (lung), and MCF-7 (breast) cancer cells (IC50 ≈ 1.0 μM), as well as 3D multicellular tumor spheroids, under low-energy visible (400-700 nm) and red-light (660 nm). This effect is mediated by cytotoxic singlet oxygen and proceeds via an apoptotic mechanism. Importantly, Mn4 displays significantly lower toxicity toward normal HPL1D lung and HEK-293 kidney cells under similar conditions. Cellular uptake studies reveal selective accumulation of Mn4 in A549 cancer cells, with mitochondrial localization, and negligible accumulation in BEAS-2B normal lung cells. Furthermore, 3D optical tumor imaging demonstrated Mn4's selective tumor accumulation in a 4T1 breast tumor-bearing in vivo mouse model. In vivo efficacy studies using a 4T1 tumor-bearing orthotopic mouse model show that Mn4 significantly reduces tumor volume and weight in a dose-dependent manner under low-energy blue laser (450 nm) irradiation, highlighting its potential as an effective photodynamic therapy (PDT) agent. Toxicological studies confirm that Mn4 does not induce abnormal biochemical or hematological parameters in healthy mice. To our knowledge, this is the first report of a Mn(II) complex with curcumin and the first example of a metal complex with curcumin for combined in vivo PDT and noninvasive 3D optical tumor imaging, paving the way for nonmacrocyclic Mn-based cancer phototheranostics.

From Natural Product Derivative to Hexagonal Prism Supermolecule: Potent Biofilm Disintegration, Enhanced Foliar Affinity, and Effective Management of Tomato Bacterial Canker

Clavibacter michiganensis (Cmm), designated as an A2 quarantine pest by the European and Mediterranean Plant Protection Organization (EPPO), incites bacterial canker of tomato, which presently eludes rapid and effective control methodologies. Dense biofilms formed by Cmm shield internal bacteria from host immune defenses and obstruct the ingress of agrochemicals. Even when agrochemicals disintegrate biofilms, splashing and bouncing during application disperse active ingredients away from target sites. Herein, we present a supramolecular strategy to fabricate a hexagonal prism-shaped material, BPGA@CB[8], assembled from an 18β-glycyrrhetinic acid derivative (PBGA) and host molecule-cucurbit[8]uril (CB[8]) via host-guest recognition. This positively charged material manifests multifaceted functionalities, notably the ability to surmount biofilm barriers, annihilate the encased pathogenic bacteria, and enhance foliar affinity of droplets. The strong in vitro potency and effective deposition of BPGA@CB[8] foster optimal conditions for robust in vivo efficacy, demonstrating superior protective and curative activities (56.9 %/53.4 %) against canker of tomato at a low-dose of 100 μg⋅mL-1 compared to BPGA (44.6 %/42.2 %), kasugamycin (30.1 %/28.4 %), and thiodiazole copper (35.4 %/31.0 %). This supramolecular material, based on natural product derivatives, provides a potent treatment for high-risk canker of tomato, and exemplifies the utility of supramolecular strategies in optimizing the attributes of natural products for managing plant bacterial diseases.

Regulating the Twisted Intramolecular Charge Transfer and Anti-heavy Atom Effect at Supramolecular Level for Favorable Photosensitizing Activity in Water

Photosensitizing assemblies based on twisted intramolecular charge transfer (TICT) active donor-acceptor-donor (D-A-D) system BrTPA-Qx having bromine atoms at the periphery have been developed. Through strategic incorporation of bromine atoms at the para-position to the nitrogen-carbon bonds of phenyl rings at the periphery, halogen-halogen interactions are induced in BrTPA-Qx nanoassemblies in H2O:DMSO (99:1) solution. Hence, the anti-heavy atom effect is induced, and the limitations of TICT (dark excited state) and heavy atom effect (triplet deactivation via radiative decay) could be overcome. Because of TICT and anti-heavy atom effect, supramolecular BrTPA-Qx nanoassemblies demonstrate high efficiency in promoting activation of aerial oxygen via electron and energy transfer pathways in aqueous media. The significant influence of the stabilized TICT state and anti-heavy-atom effect in controlling the ROS generation was validated through in-depth solvent-dependent photophysical studies and investigations of the structure-activity relationship in several model compounds. The notable photosensitizing activity of BrTPA-Qx nanoassemblies is manifested in their ability to efficiently catalyze the oxidative coupling of benzylamine (via type I and type II mechanisms), Knoevenagel condensation of aromatic aldehydes (type II), and oxidative hydroxylation of arylboronic acids (type I) under mild conditions.

A supramolecular photosensitizer based on triphenylamine and pyrazine with aggregation-induced emission properties for high-efficiency photooxidation reactions

Recently, there has been a great interest in the study of photocatalysts (PCs) and photosensitizers (PSs) in the field of organic photocatalysis. In the present study, a pure organic thermally activated delayed fluorescence (TADF) molecule 4,4'-(12-(pyridin-4-yl)dibenzo[f,h]pyrido[2,3-b]quinoxaline-3,6-diyl)bis(N,N-diphenylaniline) (DPQ-TPA) was designed and synthesized, which not only have excellent TADF property and small energy splitting (ΔEST), but also can self-assembly in water to form cross-linked nanoparticles with exceptional aggregation-induced emission (AIE) characteristics. DPQ-TPA exhibits excellent remarkable selectivity and notably enhances the production capacity of reactive oxygen species (ROS), particularly 1O2, which was employed as a highly effective photocatalyst in the photooxidation reaction of phosphine and hydroazobenzenes under blue light irradiation with high yields up to 94% and 91%, respectively. This work expands the potential application of (donor-acceptor) D-A type AIE-TADF molecules in photocatalytic organic transformations through supramolecular self-assembly.