Search

Summary Supramolecular macrocyclic compounds including cyclodextrin, pillararene, calixarene, and cucurbituril are a family of multifarious hosts capable of selectively binding with guests via their intrinsic cavities. They have been used as ideal functional entities on the surface of inorganic nanoparticles to improve their solubility, stability, and biocompatibility in vivo. Macrocyclic compounds can be attached onto the surface of inorganic nanoparticles via covalent or noncovalent bonds, thus acting as a versatile anchoring point, which allows reversible complexation with small molecules via host-guest recognitions. A variety of functional tags including imaging probes, targeting groups, and therapeutic agents can be introduced for further functionalization of the organic-inorganic hybrid nanoparticles. The macrocycles-based organic-inorganic nanohybrids have shown remarkable properties and significant potential in various biomedical applications thanks to the surface modification of macrocycles. Here, we review the versatile construction of macrocycles-based hybrid nanomaterial platforms and discuss their significant potential in biomedical and related applications.

Photo-assisted therapy has been an advancing branch in the fields of modern theranostics and nanomedicine, holding observable superiorities such as noninvasiveness, deep tissue penetration, and spatial precision. Aggregation-induced emission luminogens (AIEgens) have emerged as powerful fluorescent materials and organic optical agents capable of performing therapeutic effects under light activation. In this review, we underscore the elaborate design and fabrication of AIEgen-based supramolecular materials for applications in the scope of photo-assisted therapy, including photothermal therapy, photodynamic therapy, and photo-induced reactions. With the aid of supramolecular self-assembly, AIE materials are endowed with higher biocompatibility, better specificity, external stimuli responsiveness, and integrated functionalities. AIEgen-based self-assembled materials categorized by different supramolecular driving forces are summarized with their respective features in both structures and therapeutic effects fully described. With these highly adjustable physicochemical properties of supramolecular assemblies, the functions of such AIE materials can be considerably expanded and optimized, also opening up possibilities for controllable multimodal theranostics. In the conclusion part, perspectives and remaining challenges in this research area are discussed.

Multifunctional supramolecular nanoplatforms that integrate the advantages of different therapeutic techniques can trigger multimodal synergistic treatment of tumors, thus representing an emerging powerful tool for cancer therapeutics. Methods: In this work, we design and fabricate a multifunctional supramolecular drug delivery platform, namely Fa-mPEG@CP5-CuS@HMSN-Py nanoparticles (FaPCH NPs), consisting of a pyridinium (Py)-modified hollow mesoporous silica nanoparticles-based drug reservoir (HMSN-Py) with high loading capacity, a layer of NIR-operable carboxylatopillar[5]arene (CP5)-functionalized CuS nanoparticles (CP5-CuS) on the surface of HMSN-Py connected through supramolecular host-guest interactions between CP5 rings and Py stalks, and another layer of folic acid (Fa)-conjugated polyethylene glycol (Fa-PEG) antennas by electrostatic interactions capable of active targeting at tumor lesions, in a controlled, highly integrated fashion for synergistic chemo-photothermal therapy. Results: Fa-mPEG antennas endowed the enhanced active targeting effect toward cancer cells, and CP5-CuS served as not only a quadruple-stimuli responsive nanogate for controllable drug release but also a special agent for NIR-guided photothermal therapy. Meanwhile, anticancer drug doxorubicin (DOX) could be released from the HMSN-Py reservoirs under tumor microenvironments for chemotherapy, thus realizing multimodal synergistic therapeutics. Such a supramolecular drug delivery platform showed effective synergistic chemo-photothermal therapy both in vitro and in vivo. Conclusion: This novel supramolecular nanoplatform possesses great potential in controlled drug delivery and tumor cellular internalization for synergistic chemo-photothermal therapy, providing a promising approach for multimodal synergistic cancer treatment.

Pillar[5]arene tetramers with tetraphenylethene cores and different lengths of alkyl ether chains (H1-4C4P and H2-2C4P) and a 9,10-distyrylanthrace-bridged neutral guest linker (DSA-G) are synthesized to fabricate tunable solid-state fluorescent materials through supramolecular assemblies of DSA-G⊂H1-4C4P and DSA-G⊂H2-2C4P. Their fluorescence emission is strongly enhanced and their colors are changed upon assembly, which can be ascribed to the supramolecular assembly-induced enhanced emission and Forster resonance energy transfer (FRET) processes between H1-4C4P (or H2-2C4P) and DSA-G. Both ensembles of DSA-G⊂H1-4C4P and DSA-G⊂H2-2C4P exhibit thermo and solvent dual-responsive features, while DSA-G⊂H2-2C4P shows higher sensitivity toward external stimuli as compared to DSA G⊂H1-4C4P due to the shorter distance between fluorophores. The use of these fluorescent materials as inks confirms their efficiencies in the solid-state, paving the way for new potential applications of smart optical materials based on supramolecular assemblies.

Tunable luminescent materials are becoming more and more important owing to their broad application potential in various fields. Here we construct a pillar[5]arene-based hybrid material with stimuli-responsive luminescent properties and ion-sensing abilities from a pyridine-modified conjugated pillar[5]arene and a planar chromophore oligo(phenylenevinylene) upon coordination of Cd (II) metal cores. This new material not only shows an optimized luminescence due to the minimized π–π stacking and efficient charge transfer properties benefitting from the existence of pillar[5]arene rings, but also exhibits tunable multicolor emission induced by different external stimuli including solvent, ions and acid, indicating great application potential as a fluorescent sensory material, especially for Fe3+. With this pillar[5]arene-based dual-ligand hybrid material, valid optimization and regulation on the fluorescence of the original chromophore have been achieved, which demonstrates a plausible strategy for the design of tunable solid-state luminescent materials and also a prototypical model for the effective regulation of fluorescent properties of planar π systems using synthetic macrocycle-based building blocks., For higher tunability, brighter emission, and extra colors of luminescent materials, one can simply use some pillars (pillar[n]arenes) to facilitate material construction.

With the rapid development of supramolecular chemistry and nanomaterials, supramolecular nanotheranostics has attracted remarkable attention owing to the advantages compared with conventional medicine. Supramolecular architectures relying on non-covalent interactions possess reversible and stimuli-responsive features; endowing supramolecular nanotheranostics based on supramolecular assemblies great potentials for the fabrication of integrated novel nanomedicines and controlled drug delivery systems. In particular, pillarenes, as a relatively new class of synthetic macrocycles, are important candidates in the construction of supramolecular therapeutic systems due to their excellent features such as rigid and symmetric structures, facile substitution, and unique host-guest properties. This review summarizes the development of pillarene-based supramolecular nanotheranostics for applications in biological mimicking, virus inhibition, cancer therapy, and diagnosis, which contains the following two major parts: (a) pillarene-based hybrid supramolecular nanotheranostics upon hybridizing with porous materials such as mesoporous silica nanoparticles, metal-organic frameworks, metal nanoparticles, and other inorganic materials; (b) pillarene-based organic supramolecular therapeutic systems that include supramolecular amphiphilic systems, artificial channels, and prodrugs based on host-guest complexes. Finally, perspectives on how pillarene-based supramolecular nanotheranostics will advance the field of pharmaceuticals and therapeutics are given.

We construct a fluorescent supramolecular system (TPE-Q 4 ⊂ DSP5) of excellent tolerance to a wide range of pH by the facile self-assembly of a new pillar [ 5 ] arene bearing disulfonated arms (DSP5) with an AIE-active tetraphenylethene-based tetratopic guest bearing four quaternary ammonium binding sites (TPE-Q 4 ), which exhibits strong blue emission even in dilute aqueous solutions along with much higher quantum yield and longer fluorescence lifetime than TPE-Q 4 itself. This appreciable property can be attributed to the supramolecular assembly-induced emission (SAIE) mechanism endowed by the host-guest inclusion complexation based on synthetic macrocycles. Remarkably, the enhanced fluorescence of the supramolecular assembly is quenched efficiently and exclusively by ferric ions in water with a high Stern–Volmer formula constant of 1.3 × 10 5 m o l - 1 , demonstrating the excellent cation selectivity and visualized responsiveness in ion sensing and detection.

The fabrication of smart materials is gradually becoming a research focus in nanotechnology and materials science. An important criterion of smart materials is the capacity of stimuli-responsiveness, while another lies in selective recognition. Accordingly, supramolecular host-guest chemistry has proven a promising support for building intelligent, responsive systems; hence, synthetic macrocyclic hosts, such as calixarenes, cucurbiturils, cyclodextrins, and pillararenes, have been used as ideal building blocks. Meanwhile, manipulating and harnessing light artificially is always an intensive attempt for scientists in order to meet the urgent demands of technological developments. Fluorescence resonance energy transfer (FRET), known as a well-studied luminescent activity and also a powerful tool in spectroscopic area, has been investigated from various facets, of which the application range has been broadly expanded. In this review, the innovative collaboration between FRET and supramolecular macrocyclic chemistry will be presented and depicted with typical examples. Facilitated by the dynamic features of supramolecular macrocyclic motifs, a large variety of FRET systems have been designed and organized, resulting in promising optical materials with potential for applications in protein assembly, enzyme assays, diagnosis, drug delivery monitoring, sensing, photosynthesis mimicking and chemical encryption.