pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

Stimuli-responsive delivery systems using carbohydrate polymers: A review

Carbohydrate polymers, including Chitosan, Cellulose, Starch, Dextran, Pectin, Alginate, and Hyaluronic Acid, have been considered as stimuli-responsive biopolymers demonstrating significant potential for drug delivery approaches. Relying on the specific design and fabrication, such biopolymers are able to respond to fluctuations in pH, temperature, or enzymatic activity. This review investigates stimuli-responsive biopolymers, known as carbohydrate polymers, mainly chitosan, cellulose, and alginate, utilized as drug delivery approaches, emphasizing that these stimuli-responsive biopolymers accelerate controlled drug release. The pH-responsive delivery systems selectively target acidic tumor microenvironments, while temperature-responsive materials provide precise control for drug release produced by hyperthermia. Light-responsive biopolymers provide spatial and temporal control, providing appropriate for targeted therapy. Redox-responsive structures are especially efficient in responding to elevated glutathione (GSH) in tumor microenvironment, facilitating targeted drug release. Electro- and magnetic-responsive systems provide remote control functionalities, improving the accuracy of drug administration. The incorporation of multi-stimuli-responsive mechanisms implies a remarkable progression in drug delivery, providing a more versatile and adaptable framework for therapeutic applications. Accordingly, the future research on carbohydrate polymer-based stimuli-responsive delivery systems should focus on improving the responsiveness and targeting efficacy through complicated optimization of features and performance of carbohydrate polymers, where the integration of multifunctional moieties facilitates transformation of targeted drugs for broader biological functions.

Chitosan based fluorescent probe with AIE property for detection of Fe3+ and bacteria

Fluorescent probe with aggregation-induced emission (AIE) property has been widely used because of the advantages of high sensitivity, good selectivity and non-destructive testing. The development of fluorescent probe with good biocompatibility, photostability and biodegradability is of great significance in biomedicine and environmental detection. Herein, a novel type of fluorophore CS-TPE for detection of Fe3+ and bacteria was prepared by the Schiff base reaction of chitosan (CS) and 4-(1,2,2-triphenylethenyl) benzaldehyde (TPE-CHO). The fluorescence response mechanism of CS-TPE system was investigated by various characterization techniques. CS-TPE had an obvious AIE behavior with strong blue-green emissions at 473 nm and reaches the highest photoluminescence (PL) emission in 90 % H2O/ethanol mixtures. CS-TPE fluorescent probe exhibited sensitive quenching response to Fe3+, which can be used as a biosensor for detecting the concentration of Fe3+ with short response time (5 min), low detection limit (0.998 μM) and wide detection range (10-300 μM). Meanwhile, CS-TPE exhibited good antibacterial performance for S. aureus and E. coli. It is expected to realize the real-time fluorescence monitoring of metal ion detection and antibacterial process.

pH-Responsive supramolecular vesicles for imaging-guided drug delivery: Harnessing aggregation-induced emission

The water-soluble tribenzotriquinacene-based hexacarboxylic acid ammonium salt, TBTQ-C 6 , acts as the host component (H) forming host-guest complexes with tetraphenylethylene (TPE)-functionalized monotopic and tetratopic quaternary ammonium derivatives, G1 and G2, to yield supra-amphiphiles. These supra-amphiphiles self-assemble to form pH-responsive fluorescent vesicles, which have allowed us to capitalize on the aggregation-induced emission (AIE) effect for imaging-guided drug delivery systems. These systems exhibit efficient drug loading and pH-responsive delivery capabilities. Upon encapsulation of the anticancer drug doxorubicin (DOX), both the TPE and DOX chromophores undergo dual-fluorescence deactivation due to the energy transfer relay (ETR) effect. Under acidic conditions, the release of DOX interrupts the ETR effect, resulting in the fluorescence recovery of TPE fluorogens and DOX, allowing for real-time visual monitoring of the drug release process. Cytotoxicity experiments confirmed the low toxicity of the unloaded vectors to normal cells, while the DOX-loaded vectors were found to significantly enhance the anticancer activity of DOX against cancer cells in vitro. The AIE-featured supramolecular vesicles presented in this research hold great potential for imaging-guided drug delivery systems.

A Molecular Cage Accessed by Threefold Click Reaction of a C3v-Symmetric Triazido-Functionalized Tribenzotriquinacene

The hitherto unknown hexakis(halomethyl)-functionalized tribenzotriquinacenes (TBTQs) 9 and 10 were synthesized from the key 4b,8b,12b-tribromo-TBTQ derivative 6 by an improved route in 67% overall yield. Extension of the bowl-shaped framework of 9 or 10 by threefold condensation with propargylamine or 2-azidoethylamine afforded the corresponding TBTQ-trialkyne 11 and TBTQ-triazide 12, respectively. While attempts to construct bis-TBTQ cages, including homodimerization of 11 and heterocoupling of 11 with 12, were unsuccessful, triazide 12 was found to undergo threefold [3 + 2]-cycloaddition with 3-ethynylaniline and phloroglucinol tripropargyl ether under click chemistry conditions. The latter reaction enabled facile capping of the TBTQ bowl to give the novel cage compound 5 in 22% yield.