Supramolecular nanotheranostics based on pillarenes

Cucurbit[8]uril-based supramolecular theranostics

Different from most of the conventional platforms with dissatisfactory theranostic capabilities, supramolecular nanotheranostic systems have unparalleled advantages via the artful combination of supramolecular chemistry and nanotechnology. Benefiting from the tunable stimuli-responsiveness and compatible hierarchical organization, host-guest interactions have developed into the most popular mainstay for constructing supramolecular nanoplatforms. Characterized by the strong and diverse complexation property, cucurbit[8]uril (CB[8]) shows great potential as important building blocks for supramolecular theranostic systems. In this review, we summarize the recent progress of CB[8]-based supramolecular theranostics regarding the design, manufacture and theranostic mechanism. Meanwhile, the current limitations and corresponding reasonable solutions as well as the potential future development are also discussed.

Recent Progress of Supramolecular Chemotherapy Based on Host-Guest Interactions

Chemotherapy is widely recognized as an effective approach for treating cancer due to its ability to eliminate cancer cells using chemotherapeutic drugs. However, traditional chemotherapy suffers from various drawbacks, including limited solubility and stability of drugs, severe side effects, low bioavailability, drug resistance, and challenges in tracking treatment efficacy. These limitations greatly hinder its widespread clinical application. In contrast, supramolecular chemotherapy, which relies on host-guest interactions, presents a promising alternative by offering highly efficient and minimally toxic anticancer drug delivery. In this review, an overview of recent advancements in supramolecular chemotherapy based on host-guest interactions is provided. The significant role it plays in guiding cancer therapy is emphasized. Drawing on a wealth of cutting-edge research, herein, a timely and valuable resource for individuals interested in the field of supramolecular chemotherapy or cancer therapy, is presented. Furthermore, this review contributes to the progression of the field of supramolecular chemotherapy toward clinical application.

Pillar[n]arenes in the Fight against Biofilms: Current Developments and Future Perspectives

The global surge in bacterial infections, compounded by the alarming escalation of drug-resistant strains, has evolved into a critical public health crisis. Among the challenges posed, biofilms stand out due to their formidable resistance to conventional antibiotics. This review delves into the burgeoning potential of pillar[n]arenes, distinctive macrocyclic host molecules, as promising anti-biofilm agents. The review is structured into two main sections, each dedicated to exploring distinct facets of pillar[n]arene applications. The first section scrutinizes functionalized pillar[n]arenes with a particular emphasis on cationic derivatives. This analysis reveals their significant efficacy in inhibiting biofilm formation, underscoring the pivotal role of specific chemical attributes in combating microbial communities. The second section of the review shifts its focus to inclusion complexes, elucidating how pillar[n]arenes serve as encapsulation platforms for antibiotics. This encapsulation enhances the stability of antibiotics and enables a controlled release, thereby amplifying their antibacterial activity. The examination of inclusion complexes provides valuable insights into the potential synergy between pillar[n]arenes and traditional antibiotics, offering a novel avenue for overcoming biofilm resistance. This comprehensive review highlights the escalating global threat of bacterial infections and the urgent need for innovative strategies to counteract drug-resistant biofilms. The unique properties of pillar[n]arenes, both as functionalized molecules and as inclusion complex hosts, position them as promising candidates in the quest for effective anti-biofilm agents. The exploration of their distinct mechanisms opens new avenues for research and development in the ongoing battle against bacterial infections and biofilm-related health challenges.

White-Light Emission from a Host-Guest Composite between Carboxylatopillar[5]arene-Modified N-Doped Carbon Dots and Rhodamine 6G for Rutin Detection

The construction of tunable white-light-emitting materials has garnered increasing attention in the scientific community. In this study, N-doped carbon dots (N-CDs) were surface-modified with carboxylatopillar[5]arene (CP[5]) using an EDC-NHS coupling reaction to create CCDs. CCDs were then conjugated with rhodamine 6G (R6G) through host-guest interactions to fabricate the CCDs-R6G composites. These composites produced two-color fluorescence emission peaks at 447 and 557 nm when excited by a wavelength of 340 nm. Excitingly, white-light emission (0.28, 0.30) can be readily achieved by varying the R6G concentration. To further explore potential applications, a new detection method for rutin (RT) based on the inner filter effect (IFE) was developed. Experimental results verify the practicality and reliability of the fluorescence sensor based on CCDs-R6G composites for RT detection in real samples.

Multiple hydrogen bonding driven supramolecular architectures and their biomedical applications

Supramolecular chemistry combines the strength of molecular assembly via various molecular interactions. Hydrogen bonding facilitated self-assembly with the advantages of directionality, specificity, reversibility, and strength is a promising approach for constructing advanced supramolecules. There are still some challenges in hydrogen bonding based supramolecular polymers, such as complexity originating from tautomerism of the molecular building modules, the assembly process, and structure versatility of building blocks. In this review, examples are selected to give insights into multiple hydrogen bonding driven emerging supramolecular architectures. We focus on chiral supramolecular assemblies, multiple hydrogen bonding modules as stimuli responsive sources, interpenetrating polymer networks, multiple hydrogen bonding assisted organic frameworks, supramolecular adhesives, energy dissipators, and quantitative analysis of nano-adhesion. The applications in biomedical materials are focused with detailed examples including drug design evolution for myotonic dystrophy, molecular assembly for advanced drug delivery, an indicator displacement strategy for DNA detection, tissue engineering, and self-assembly complexes as gene delivery vectors for gene transfection. In addition, insights into the current challenges and future perspectives of this field to propel the development of multiple hydrogen bonding facilitated supramolecular materials are proposed.

Pillararene-Based Supramolecular Polymers for Adsorption and Separation

Supramolecular polymers have attracted increasing attention in recent years due to their perfect combination of supramolecular chemistry and traditional polymer chemistry. The design and synthesis of macrocycles have driven the rapid development of supramolecular chemistry and polymer science. Pillar[n]arenes, a new generation of macrocyclic compounds possessing unique pillar-shaped structures, nano-sized cavities, multi-functionalized groups, and excellent host-guest complexation abilities, are promising candidates to construct supramolecular polymer materials with enhanced properties and functionalities. This review summarizes recent progress in the design and synthesis of pillararene-based supramolecular polymers (PSPs) and illustrates their diverse applications as adsorption and separation materials. All performances are evaluated and analyzed in terms of efficiency, selectivity, and recyclability. Typically, PSPs can be categorized into three typical types according to their topologies, including linear, cross-linked, and hybrid structures. The advances made in the area of functional supramolecular polymeric adsorbents formed by new pillararene derivatives are also described in detail. Finally, the remaining challenges and future perspectives of PSPs for separation-based materials science are discussed. This review will inspire researchers in different fields and stimulate creative designs of supramolecular polymeric materials based on pillararenes and other macrocycles for effective adsorption and separation of a variety of targets.

Dual-Responsive Drug-Delivery System Based on PEG-Functionalized Pillararenes Containing Disulfide and Amido Bonds for Cancer Theranostics

The construction of a smart drug-delivery system based on amphiphilic pillararenes with multiple responsiveness properties has become an important way to improve the efficacy of tumor chemotherapy. Here, a new PEG-functionalized pillararene (EtP5-SS-PEG) containing disulfide and amido bonds was designed and synthesized, which has been used to construct a novel supramolecular nanocarrier through a host-guest interaction with a perylene diimide derivative (PDI-2NH4 ) and their supramolecular self-assembly. This nanocarrier showed good drug loading capability, and dual stimulus responsiveness to enzyme and GSH (glutathione). After loading of doxorubicin (DOX), the prepared nanodrugs displayed efficient DOX release and outstanding cancer theranostics ability.

Surface modification strategies in translocating nano-vesicles across different barriers and the role of bio-vesicles in improving anticancer therapy

Nanovesicles and bio-vesicles (BVs) have emerged as promising tools to achieve targeted cancer therapy due to their ability to overcome many of the key challenges currently being faced with conventional chemotherapy. These challenges include the diverse and often complex pathophysiology involving the progression of cancer, as well as the various biological barriers that circumvent therapeutic molecules reaching their target site in optimum concentration. The scientific evidence suggests that surface-functionalized nanovesicles and BVs camouflaged nano-carriers (NCs) both can bypass the established biological barriers and facilitate fourth-generation targeting for the improved regimen of treatment. In this review, we intend to emphasize the role of surface-functionalized nanovesicles and BVs camouflaged NCs through various approaches that lead to an improved internalization to achieve improved and targeted oncotherapy. We have explored various strategies that have been employed to surface-functionalize and biologically modify these vesicles, including the use of biomolecule functionalized target ligands such as peptides, antibodies, and aptamers, as well as the targeting of specific receptors on cancer cells. Further, the utility of BVs, which are made from the membranes of cells such as mesenchymal stem cells (MSCs), white blood cells (WBCs), red blood cells (RBCs), platelets (PLTs) as well as cancer cells also been investigated. Lastly, we have discussed the translational challenges and limitations that these NCs can encounter and still need to be overcome in order to fully realize the potential of nanovesicles and BVs for targeted cancer therapy. The fundamental challenges that currently prevent successful cancer therapy and the necessity of novel delivery systems are in the offing.

Synthetic Receptors for Early Detection and Treatment of Cancer

Over recent decades, synthetic macrocyclic compounds have attracted interest from the scientific community due to their ability to selectively and reversibly form complexes with a huge variety of guest moieties. These molecules have been studied within a wide range of sensing and other fields. Within this review, we will give an overview of the most common synthetic macrocyclic compounds including cyclodextrins, calixarenes, calixresorcinarenes, pillarenes and cucurbiturils. These species all display the ability to form a wide range of complexes. This makes these compounds suitable in the field of cancer detection since they can bind to either cancer cell surfaces or indeed to marker compounds for a wide variety of cancers. The formation of such complexes allows sensitive and selective detection and quantification of such guests. Many of these compounds also show potential for the detection and encapsulation of environmental carcinogens. Furthermore, many anti-cancer drugs, although effective in in vitro tests, are not suitable for use directly for cancer treatment due to low solubility, inherent instability in in vivo environments or an inability to be adsorbed by or transported to the required sites for treatment. The reversible encapsulation of these species in a macrocyclic compound can greatly improve their solubility, stability and transport to required sites where they can be released for maximum therapeutic effect. Within this review, we intend to present the use of these species both in cancer sensing and treatment. The various macrocyclic compound families will be described, along with brief descriptions of their synthesis and properties, with an outline of their use in cancer detection and usage as therapeutic agents. Their use in the sensing of environmental carcinogens as well as their potential utilisation in the clean-up of some of these species will also be discussed.

The design strategy for pillararene based active targeted drug delivery systems

Pillararenes have columnar architectures with electron-rich cavities to endow themselves with unique host-guest complexation capability. Easy structural modifiability facilitates them to be used in many applications. Currently, pillararene based drug delivery systems (DDSs) have been developed as a powerful tool for precise diagnosis and treatment of cancer. Various functional guest molecules could be integrated with pillararenes to construct nanomaterials for cancer chemotherapy, phototherapy and chemodynamic therapy. In order to improve cancer therapy efficacy, active targeted DDSs have become particularly important. Benefiting from the good host-guest properties and structural variability of pillararenes, tumor targeting groups could be easily introduced into pillararene based DDSs to realize precise drug delivery at tumor sites. In this feature article, we provide a comprehensive summary of the present design strategy for pillararene based active targeted DDSs, which can be classified into three types namely host-guest complexation, charge reversal and targeted group modified pillararenes. Some important examples are selected to for a detailed discussion on their respective strengths and weaknesses.

The Creation of DNA Origami-Based Supramolecular Nanostructures for Cancer Therapy

DNA origami technology, a unique type of DNA nanotechnology, has attracted much attention from researchers and is applied in various fields. Through exquisite design and precise self-assembly of four kinds of deoxyribonucleotides, DNA origami nanostructures are endowed with excellent programmability and addressability and show outstanding biocompatibility in bio-related applications, especially in cancer treatment. In this review, nanomaterials based on DNA origami for cancer therapy are concluded, whereby chemotherapy and photo-assisted therapy are the main focus. Furthermore, the working mechanisms of the functional materials attached to the rigid DNA structures to enable targeted delivery and circumvent drug resistance are also discussed. DNA origami nanostructures are valuable carriers for delivering multifunctional therapeutic agents and demonstrate great potential in cancer treatment both in vitro and in vivo. It is undoubted that DNA origami technology is a promising strategy for constructing versatile nanodevices in biological fields and will excel in human healthcare.

Harnessing Pillar[5]arene Host-Guest Complexation To Improve pH Stability and Affect Enzymatic Degradation of the Anticancer Prodrug Capecitabine: A 19 F NMR Study

Cancer is a global health problem, and supramolecular chemotherapy is emerging as a novel strategy to battle the disease. Here, we first evaluated the thermodynamic and kinetic stability of the complexes formed between several water-soluble per-substituted pillar[5]arene derivatives and capecitabine (1), a widely used oral chemotherapeutic prodrug. The exchange rate was studied, for the first time in pillararene chemistry, by the 19 F guest exchange saturation transfer (GEST) NMR technique. Importantly, when we evaluated the effect of complexation on the characteristics of 1, we found that the complexation of 1 with such pillar[5]arene hosts increased capecitabine stability at acidic pH very significantly and slowed its enzymatic degradation by the carboxylesterase enzyme in a manner that depended on the host. These interesting findings could have implications on the clinical use of this heavily used prodrug and might affect the management of cancer patients.

Pillararenes as Promising Carriers for Drug Delivery

Since their discovery in 2008 by N. Ogoshi and co-authors, pillararenes (PAs) have become popular hosts for molecular recognition and supramolecular chemistry, as well as other practical applications. The most useful property of these fascinating macrocycles is their ability to accommodate reversibly guest molecules of various kinds, including drugs or drug-like molecules, in their highly ordered rigid cavity. The last two features of pillararenes are widely used in various pillararene-based molecular devices and machines, stimuli-responsive supramolecular/host-guest systems, porous/nonporous materials, organic-inorganic hybrid systems, catalysis, and, finally, drug delivery systems. In this review, the most representative and important results on using pillararenes for drug delivery systems for the last decade are presented.

Pillararene-Based Supramolecular Polymers for Cancer Therapy

Supramolecular polymers have attracted considerable interest due to their intriguing features and functions. The dynamic reversibility of noncovalent interactions endows supramolecular polymers with tunable physicochemical properties, self-healing, and externally stimulated responses. Among them, pillararene-based supramolecular polymers show great potential for biomedical applications due to their fascinating host-guest interactions and easy modification. Herein, we summarize the state of the art of pillararene-based supramolecular polymers for cancer therapy and illustrate its developmental trend and future perspective.

Multifunctional metal-organic framework (MOF)-based nanoplatforms for cancer therapy: from single to combination therapy

Cancer remains a severe threat to human health. To date, although various therapeutic methods, including radiotherapy (RT), chemotherapy, chemodynamic therapy (CDT), phototherapy, starvation therapy, and immunotherapy, have entered a new stage of rapid progress in cancer theranostics, their limited therapeutic effect and significant side effects need to be considered carefully. With the rapid development of nanotechnology, the marriage of nanomaterials and therapeutic methods provides the practical possibility to improve the deficiencies in cancer therapy. Notably, metal-organic frameworks (MOFs) composed of ions/clusters and bridging ligands through coordination bonds have been widely applied in cancer therapy to deal with the drawbacks of different therapeutic methods, such as severe side effects, low stability, and poor efficacy, owing to their controllable morphologies, tailorable diameters, diverse compositions, tunable porosities, high specific surface areas, facile functionalization, and good biocompatibility. This review summarizes the recent advanced developments and achievements of multifunctional MOF-based nanoplatforms for cancer therapy through single therapy methods, including RT, chemotherapy, CDT, phototherapy (photodynamic and photothermal therapy), starvation therapy and immunotherapy, and combination therapy methods. Moreover, the prospects and challenges of MOF-based nanoplatforms used in tumor therapy are also discussed.

Molecular recognition of methylated amino acids and peptides by Pillar[6]MaxQ

We report the molecular recognition properties of Pillar[n]MaxQ (P[n]MQ) toward a series of (methylated) amino acids, amino acid amides, and post-translationally modified peptides by a combination of 1H NMR, isothermal titration calorimetry, indicator displacement assays, and molecular dynamics simulations. We find that P6MQ is a potent receptor for N-methylated amino acid side chains. P6MQ recognized the H3K4Me3 peptide with Kd = 16 nM in phosphate buffered saline.

A Water-Soluble Leggero Pillar[5]arene

The study of aqueous-phase molecular recognition of artificial receptors is one of the frontiers in supramolecular chemistry since most biochemical processes and reactions take place in an aqueous medium and heavily rely on it. In this work, a water-soluble version of leggero pillar[5]arene bearing eight positively charged pyridinium moieties (CWP[5]L) was designed and synthesized, which exhibited good binding affinities with certain aliphatic sulfonate species in aqueous solutions. Significantly, control experiments demonstrate that the guest binding performance of CWP[5]L is superior to its counterpart water-soluble macrocyclic receptor in traditional pillararenes.

Host-guest interaction-based supramolecular prodrug self-assemblies for GSH-consumption augmented chemotherapy

The over-expressed cellular glutathione (GSH) severely restricts the chemotherapeutic efficacy due to the GSH-induced detoxification of chemical drugs. Herein, how to construct effective drug delivery systems with GSH-consumption property is still a general concern and a major challenge. In this study, the host-guest interactions between water-soluble pillar[6]arene (WP[6]) and chlorambucil-arylboronic acid (Cb-BA) were utilized to construct supramolecular prodrug self-assemblies (SPSAs) with specific stimuli-responsive property. Notably, the BA moiety could not only consume GSH but also rapidly bind curcumin (Cur), which could inhibit the thioredoxin reductase (TrxR) to further reduce the GSH biosynthesis pathway. Benefiting from the functionality of BA-Cur conjugates, the GSH levels could be significantly downregulated, paving a novel way to enhance chemotherapeutic efficacy. In vitro and in vivo investigations demonstrated that this two-pronged GSH-depletion strategy could amplify the cellular oxidative stress and achieve excellent anti-tumor efficacy.

Porous Silicon Nanocarriers with Stimulus-Cleavable Linkers for Effective Cancer Therapy

Porous silicon nanoparticles (pSiNPs) are widely utilized as drug carriers due to their excellent biocompatibility, large surface area, and versatile surface chemistry. However, the dispersion in pore size and biodegradability of pSiNPs arguably have hindered the application of pSiNPs for controlled drug release. Here, a step-changing solution to this problem is described involving the design, synthesis, and application of three different linker-drug conjugates comprising anticancer drug doxorubicin (DOX) and different stimulus-cleavable linkers (SCLs) including the photocleavable linker (ortho-nitrobenzyl), pH-cleavable linker (hydrazone), and enzyme-cleavable linker (β-glucuronide). These SCL-DOX conjugates are covalently attached to the surface of pSiNP via copper (I)-catalyzed alkyne-azide cycloaddition (CuAAC, i.e., click reaction) to afford pSiNP-SCL-DOXs. The mass loading of the covalent conjugation approach for pSiNP-SCL-DOX reaches over 250 µg of DOX per mg of pSiNPs, which is notably twice the mass loading achieved by noncovalent loading. Moreover, the covalent conjugation between SCL-DOX and pSiNPs endows the pSiNPs with excellent stability and highly controlled release behavior. When tested in both in vitro and in vivo tumor models, the pSiNP-SCL-DOXs induces excellent tumor growth inhibition.

Controlled release of drug molecules by pillararene-modified nanosystems

Stimuli-responsive nanosystems have attracted the interest of researchers due to their intelligent function of controlled release regulated by a variety of external stimuli and have been applied in biomedical fields. Pillar[n]arenes with the advantages of a rigid structure, electron holes and easy functionalization are considered as excellent candidates for the construction of host-guest nanosystems. In recent years, many pillararene modified nanosystems have been reported in response to different stimuli. In this feature article, we summarize the advance of stimuli-responsive pillararene modified nanosystems for controlled release of drugs from the perspectives of decomposition release and gated release, focusing on the control principles of these nanosystems. We expect that this review can enlighten and guide investigators in the field of stimuli-responsive controlled release.

Thermodynamics of Pillararene•Guest Complexation: Blinded Dataset for the SAMPL9 Challenge

We report an investigation of the complexation between a water soluble pillararene host (WP6) and a panel of hydrophobic cationic guests (G1 - G20) by a combination of ¹H NMR spectroscopy and isothermal titration calorimetry in phosphate buffered saline. We find that WP6 forms 1:1 complexes with K_a values in the 10⁴ - 10⁹ M^-1 range driven by favorable enthalpic contributions. This thermodynamic dataset serves as blinded data for the SAMPL9 challenge.

A dendritic polyamidoamine supramolecular system composed of pillar[5]arene and azobenzene for targeting drug-resistant colon cancer

Fusobacterium nucleatum caused drug-resistant around tumor sites often leads to the failure of chemotherapy during colorectal cancer (CRC) treatment. Multifunctional cationic quaternary ammonium materials have been widely used as broad-spectrum antibacterial agents in antibacterial and anticancer fields. Herein, we design a smart supramolecular quaternary ammonium nanoparticle, namely quaternary ammonium PAMAM-AZO@CP[5]A (Q-P-A@CP[5]A), consisting of azobenzene (AZO)-conjugated dendritic cationic quaternary ammonium polyamidoamine (PAMAM) as the core and carboxylatopillar[5]arene (CP[5]A)-based switch, for antibacterial and anti-CRC therapies. The quaternary ammonium-PAMAM-AZO (Q-P-A) core endows the supramolecular system with enhanced antibacterial and anticancer properties. -N⁺CH₃ groups on the surface of Q-P-A are accommodated in the CP[5]A cavity under normal conditions, which significantly improves the biocompatibility of Q-P-A@CP[5]A. Meanwhile, the CP[5]A host can be detached from -N⁺CH₃ groups under pathological conditions, achieving efficient antibacterial and antitumor therapies. Furthermore, azoreductase in the tumor site can break the -NN- bonds of AZO in Q-P-A@CP[5]A, leading to the morphology recovery of supramolecular nanoparticles and CRC therapy through inducing cell membrane rupture. Both in vitro and in vivo experiments demonstrate that Q-P-A@CP[5]A possesses good biocompatibility, excellent antibacterial effect, and CRC treatment capability with negligible side effects. This supramolecular quaternary ammonium system provides an effective treatment method to overcome chemotherapy-resistant cancer caused by bacteria.

Aggregation Mode, Host-Guest Chemistry in Water, and Extraction Capability of an Uncharged, Water-Soluble, Liquid Pillar[5]arene Derivative

An uncharged, water-soluble per-ethylene-glycol pillar[5]arene derivative (1) was synthesized and its aggregation mode, host-guest chemistry in water and extraction ability was explored. Compound 1 is a liquid at room temperature; in water, limited self-aggregation occurred at high concentrations as deduced from diffusion NMR and dynamic light scattering. Compound 1 forms pseudo-rotaxane-like 1 : 1 host-guest complexes with 1,ω-di-substituted alkanes with association constants on the order of 103 -104  m-1 . Interestingly, NMR experiments showed that the guest location relative to the host ring system differs among the different complexes. In proof-of-concept experiments, compound 1 was shown to extract structurally related organic compounds from benzene into water with significant selectivity. Compound 1, which is a liquid at room temperature and has only limited interactions with its side arms, can, in principle, be regarded as a complement to or as a kind of type I porous liquid.

Supramolecular lipid nanoparticles as delivery carriers for non-invasive cancer theranostics

Nanotheranostics is an emerging frontier of personalized medicine research particularly for cancer, which is the second leading cause of death. Supramolecular aspects in theranostics are quite allured to achieve more regulation and controlled features. Supramolecular nanotheranostics architecture is focused on engineering of modular supramolecular assemblies benefitting from their mutable and stimuli-responsive properties which confer an ultimate potential for the fabrication of unified innovative nanomedicines with controlled features. Amalgamation of supramolecular approaches to nano-based features further equip the potential of designing novel approaches to overcome limitations seen by the conventional theranostic strategies, for curing even the lethal diseases and endowing personalized therapeutics with optimistic prognosis, endorsing their clinical translation. Among many potential nanocarriers for theranostics, lipid nanoparticles (LNPs) have shown various promising advances in theranostics and their formulation can be tailored for several applications. Despite the great advancement in cancer nanotheranostics, there are still many challenges that need to be highlighted to fill the literature gap. For this purpose, herein, we have presented a systematic overview on the subject and proposed LNPs as the potential material to manage cancer via non-invasive approaches by highlighting the use of supramolecular approaches to make them robust for cancer theranostics. We have concluded the review by entailing the future perspectives of lipid nanotheranostics towards clinical translation.

Water-soluble pillar[5]arene sulfo-derivatives self-assemble into biocompatible nanosystems to stabilize therapeutic proteins

Pillar[5]arenes containing sulfonate fragments have been shown to form supramolecular complexes with therapeutic proteins to facilitate targeted transport with an increased duration of action and enhanced bioavailability. Regioselective synthesis was used to obtain a water-soluble pillar[5]arene containing the fluorescent label FITC and nine sulfoethoxy fragments. The pillar[5]arene formed complexes with the therapeutic proteins binase, bleomycin, and lysozyme in a 1:2 ratio as demonstrated by UV-vis and fluorescence spectroscopy. The formation of stable spherical nanosized macrocycle/binase complexes with an average particle size of 200 nm was established by dynamic light scattering and transmission electron microscopy. Flow cytometry demonstrated the ability of macrocycle/binase complexes to penetrate into tumor cells where they exhibited significant cytotoxicity towards A549 cells at 10^-5-10^-6 M while maintaining the enzymatic activity of binase.

MOF-based multi-stimuli-responsive supramolecular nanoplatform equipped with macrocycle nanovalves for plant growth regulation

Controllable and on-demand delivery of agrochemicals such as plant hormones is conducive to improving agrochemicals utilization, tackling water and environmental pollution, reducing soil acidification, and realizing the goals of precision agriculture. Herein, a smart plant hormone delivery system based on metal-organic frameworks (MOFs) and supramolecular nanovalves, namely gibberellin (GA)-loaded CLT6@PCN-Q, is constructed through supramolecular host-guest interaction to regulate the growth of dicotyledonous Chinese cabbage and monocotyledonous wheat. The porous nanoscale MOF (NMOF) with a uniform diameter of 97 nm modified by quaternary ammonium (Q) stalks is served as a cargo reservoir, followed by the decoration of carboxylated leaning tower[6]arene (CLT6) based nanovalves on NMOF surfaces through host-guest interactions to fabricate CLT6@PCN-Q with a diameter of ∼101 nm and a zeta potential value of -13.2 mV. Interestingly, the as-fabricated supramolecular nanoplatform exhibits efficient cargo loading and multi-stimuli-responsive release under various external stimuli including pH, temperature, and competitive agent spermine (SPM), which can realize the on-demand release of cargo. In addition, GA-loaded CLT6@PCN-Q is capable of effectively promoting the seeds germination of wheat and stem growth of dicotyledonous Chinese cabbage and monocotyledonous wheat (1.86 and 1.30 times of control groups, respectively). The smart supramolecular nanoplatform based on MOFs and supramolecular nanovalves paves a way for the controlled delivery of plant hormones and other agrochemicals for promoting plant growth, offering new insights and methods to realize precision agriculture. STATEMENT OF SIGNIFICANCE: To achieve controllable and sustainable release of cargos such as agrochemicals, a smart MOF-based multi-stimuli-responsive supramolecular nanoplatform equipped with supramolecular nanovalves was fabricated via the host-guest interaction between quaternary ammonium stalks-functionalized nanoMOFs and water-soluble leaning tower[6]arene. The as-prepared supramolecular nanoplatform with uniform diameter distribution demonstrated good cargo release in response to various external stimuli. The installation of synthetic macrocycles could effectively reduce cargo loss in the pre-treatment process. This type of supramolecular nanoplatform exhibited good promoting effect on seed germination and plant growth dicotyledonous Chinese cabbage and monocotyledonous wheat. As an eco-friendly, controlled, and efficient cargo delivery system, this supramolecular nanoplatform will be a promising candidate in precision agriculture and controlled drug release to attract the broad readership.

GSH/ROS Dual-Responsive Supramolecular Nanoparticles Based on Pillar[6]arene and Betulinic Acid Prodrug for Chemo-Chemodynamic Combination Therapy

Chemodynamic therapy (CDT) based on intracellular Fenton reactions is attracting increasing interest in cancer treatment. A simple and novel method to regulate the tumor microenvironment for improved CDT with satisfactory effectiveness is urgently needed. Therefore, glutathione (GSH)/ROS (reactive oxygen species) dual-responsive supramolecular nanoparticles (GOx@BNPs) for chemo–chemodynamic combination therapy were constructed via host–guest complexation between water-soluble pillar[6]arene and the ferrocene-modified natural anticancer product betulinic acid (BA) prodrug, followed by encapsulation of glucose oxidase (GOx) in the nanoparticles. The novel supramolecular nanoparticles could be activated by the overexpressed GSH and ROS in the tumor microenvironment (TME), not only accelerating the dissociation of nanoparticles—and, thus, improving the BA recovery and release capability in tumors—but also showing the high-efficiency conversion of glucose into hydroxyl radicals (·OH) in succession through intracellular Fenton reactions. Investigation of antitumor activity and mechanisms revealed that the dramatic suppression of cancer cell growth induced by GOx@BNPs was derived from the elevation of ROS, decrease in ATP and mitochondrial transmembrane potential (MTP) and, finally, cell apoptosis. This work presents a novel method for the regulation of the tumor microenvironment for improved CDT, and the preparation of novel GSH/ROS dual-responsive supramolecular nanoparticles, which could exert significant cytotoxicity against cancer cells through the synergistic interaction of chemodynamic therapy, starvation therapy, and chemotherapy (CDT/ST/CT).

Recyclable Supramolecular Assembly-Induced Emission System for Selective Detection and Efficient Removal of Mercury(II)

An efficient strategy for simultaneously detecting and removing Hg²⁺ from water is vital to address mercury pollution. Herein a supramolecular assembly G⊂H with photoluminescent properties is facilely constructed through the self-assembly of a functional pillar[5]arene bearing two N,N-dimethyldithiocarbamoyl binding sites (H) and an AIE-active tetraphenylethene derivative (G). Remarkably, the fluorescence of G⊂H can be exclusively quenched by Hg²⁺ among the 30 cations due to the formation of non-luminous ground state complex and only L-cysteine can restore fluorescence in the common 20 amino acids. Meanwhile, the probe G⊂H has a considerable thermal and pH stability, a good anti-interference property from various cations, and a satisfactory sensitivity. More importantly, G⊂H exhibits a prominent capability of Hg²⁺ removal with rapid capture rate (within 1 h) and excellent adsorption efficiency (98 %), as well as a highly efficient recyclability without losing any adsorption activity.

Supramolecular Nanoplatform Based on Mesoporous Silica Nanocarriers and Pillararene Nanogates for Fungus Control

Synthetic fungicides have been widely used to protect crops from fungal diseases. However, excessive use of synthetic fungicides leads to the generation of fungicide resistance in fungal pathogens. Recently, smart cargo delivery systems have been introduced for the construction of a pesticide delivery nanoplatform, benefiting from their controlled release performance. Herein, a fungal pathogen microenvironment-responsive supramolecular fungicide nanoplatform has been designed and constructed, using quaternary ammonium salt (Q)-modified mesoporous silica nanoparticles (MSN-Q NPs) as nanocarriers loaded with berberine hydrochloride (BH) and carboxylatopillar[5]arene (CP[5]A) as nanogates to form BH-loaded CP[5]A@MSN-Q NPs for effective inhibition of Botrytis cinerea. CP[5]A as nanogates can endow the fungicide nanoplatform with pH stimuli-responsive release features for the control of fungicide release. The loaded BH, as a natural plant fungicide, provides an ecofriendly alternative to synthetic fungicides for controlling B. cinerea. Interestingly, we use oxalic acid (OA) secreted by B. cinerea as a trigger so that BH can be released from the fungicide nanoplatform on demand under pathogen microenvironments for controlling B. cinerea. The experimental results indicate that the fabricated fungicide nanoplatform could effectively inhibit the mycelial growth and spore germination, providing a new way for the management of B. cinerea in actual application.

Deciphering the Supramolecular Organization of Multiple Guests Inside a Microporous MOF to Understand their Release Profile

Metal-organic frameworks (MOFs) give the opportunity of confining guest molecules into their pores even by a post-synthetic protocol. PUM168 is a Zn-based MOF characterized by microporous cavities that allows the encapsulation of a significant number of guest molecules. The pores engineered with different binding sites show a remarkable guest affinity towards a series of natural essential oils components, such as eugenol, thymol and carvacrol, relevant for environmental applications. Exploiting single crystal X-ray diffraction, it was possible to step-wisely monitor the rather complex three-components guest exchange process involving dimethylformamide (DMF, the pristine solvent) and binary mixtures of the flavoring agents. A picture of the structural evolution of the DMF-to-guest replacement occurring inside the MOF crystal was reached by a detailed single-crystal-to-single-crystal monitoring. The relation of the supramolecular arrangement in the pores with selective guests release was then investigated as a function of time and temperature by static headspace GC-MS analysis.

Nanoplatforms for Targeted Stimuli-Responsive Drug Delivery: A Review of Platform Materials and Stimuli-Responsive Release and Targeting Mechanisms

To achieve the promise of stimuli-responsive drug delivery systems for the treatment of cancer, they should (1) avoid premature clearance; (2) accumulate in tumors and undergo endocytosis by cancer cells; and (3) exhibit appropriate stimuli-responsive release of the payload. It is challenging to address all of these requirements simultaneously. However, the numerous proof-of-concept studies addressing one or more of these requirements reported every year have dramatically expanded the toolbox available for the design of drug delivery systems. This review highlights recent advances in the targeting and stimuli-responsiveness of drug delivery systems. It begins with a discussion of nanocarrier types and an overview of the factors influencing nanocarrier biodistribution. On-demand release strategies and their application to each type of nanocarrier are reviewed, including both endogenous and exogenous stimuli. Recent developments in stimuli-responsive targeting strategies are also discussed. The remaining challenges and prospective solutions in the field are discussed throughout the review, which is intended to assist researchers in overcoming interdisciplinary knowledge barriers and increase the speed of development. This review presents a nanocarrier-based drug delivery systems toolbox that enables the application of techniques across platforms and inspires researchers with interdisciplinary information to boost the development of multifunctional therapeutic nanoplatforms for cancer therapy.

Designing of Nanomaterials-Based Enzymatic Biosensors: Synthesis, Properties, and Applications

Among the many biological entities employed in the development of biosensors, enzymes have attracted the most attention. Nanotechnology has been fostering excellent prospects in the development of enzymatic biosensors, since enzyme immobilization onto conductive nanostructures can improve characteristics that are crucial in biosensor transduction, such as surface-to-volume ratio, signal response, selectivity, sensitivity, conductivity, and biocatalytic activity, among others. These and other advantages of nanomaterial-based enzymatic biosensors are discussed in this work via the compilation of several reports on their applications in different industrial segments. To provide detailed insights into the state of the art of this technology, all the relevant concepts around the topic are discussed, including the properties of enzymes, the mechanisms involved in their immobilization, and the application of different enzyme-derived biosensors and nanomaterials. Finally, there is a discussion around the pressing challenges in this technology, which will be useful for guiding the development of future research in the area.

Design Guidelines for Cationic Pillar[n]arenes that Prevent Biofilm Formation by Gram-Positive Pathogens

Bacterial biofilms are a major threat to human health, causing persistent infections that lead to millions of fatalities worldwide every year. Biofilms also cause billions of dollars of damage annually by interfering with industrial processes. Recently, cationic pillararenes were found to be potent inhibitors of biofilm formation in Gram-positive bacteria. To identify the structural features of pillararenes that result in antibiofilm activity, we evaluated the activity of 16 cationic pillar[5]arene derivatives including that of the first cationic water-soluble pillar[5]arene-based rotaxane. Twelve of the derivatives were potent inhibitors of biofilm formation by Gram-positive pathogens. Structure activity analyses of our pillararene derivatives indicated that positively charged head groups are critical for the observed antibiofilm activity. Although certain changes in the lipophilicity of the substituents on the positively charged head groups are tolerated, dramatic elevation in the hydrophobicity of the substituents or an increase in steric bulk on these positive charges abolishes the antibiofilm activity. An increase in the overall positive charge from 10 to 20 did not affect the activity significantly, but pillararenes with 5 positive charges and 5 long alkyl chains had reduced activity. Surprisingly, the cavity of the pillar[n]arene is not essential for the observed activity, although the macrocyclic structure of the pillar[n]arene core, which facilitates the clustering of the positive charges, appears important. Interestingly, the compounds found to be efficient inhibitors of biofilm formation were nonhemolytic at concentrations that are ∼100-fold of their MBIC₅₀ (the minimal concentration of a compound at which at least 50% inhibition of biofilm formation was observed compared to untreated cells). The structure–activity relationship guidelines established here pave the way for a rational design of potent cationic pillar[n]arene-based antibiofilm agents.

Unprotected Galactosamine as a Dynamic Key for a Cyclochiral Lock

The discrimination of d-galactosamine (G), representative of the amino-sugar class of compounds, has been probed through nano-ESI-FT-ICR mass spectrometry by isolating the relevant [C·H·G]+ proton-bound complexes with the enantiomers of the cyclochiral resorcin[4]arene C and allowing them to react toward three primary amines (B = EtNH2, iPrNH2, and (R)- and (S)-sBuNH2). The system under investigation presents several features that help to unveil the behavior of unprotected G in such a supramolecular architecture: (i) the hydrophobic derivatization of the C convex side forces the polar guest G to be coordinated by the cyclochiral concave region; (ii) protonated d-galactosamine exists as an anomeric mixture, dynamically interconverting throughout the experimental time-window; and (iii) different basicities of B allow the experiment to subtly tune the reactivity of the [C·H·G]+ complexes. Three [C·H·G]+ aggregate-types were found to exist, differing in both their origin and reactivity. The most reactive adducts ([C·H·G]ESI+), generated in the electrospray environment, undergo a G-to-B ligand exchange in competition with a partial isomerization to the unreactive [C·H·G]GAS+-type complexes. Finally, the poorly reactive [C·H·G]SOL+ aggregates are formed in solution over an hours-long time scale. A cyclochirality effect on the reactivity was found to depend on the considered [C·H·G]+ aggregate-type.

Supramolecular cancer nanotheranostics

Among the many challenges in medicine, the treatment and cure of cancer remains an outstanding goal given the complexity and diversity of the disease. Nanotheranostics, the integration of therapy and diagnosis in nanoformulations, is the next generation of personalized medicine to meet the challenges in precise cancer diagnosis, rational management and effective therapy, aiming to significantly increase the survival rate and improve the life quality of cancer patients. Different from most conventional platforms with unsatisfactory theranostic capabilities, supramolecular cancer nanotheranostics have unparalleled advantages in early-stage diagnosis and personal therapy, showing promising potential in clinical translations and applications. In this review, we summarize the progress of supramolecular cancer nanotheranostics and provide guidance for designing new targeted supramolecular theranostic agents. Based on extensive state-of-the-art research, our review will provide the existing and new researchers a foundation from which to advance supramolecular cancer nanotheranostics and promote translationally clinical applications.

Polydopamine-carbon dots functionalized hollow carbon nanoplatform for fluorescence-imaging and photothermal-enhanced thermochemotherapy

The low power photothermal therapy can reduce the tissue damage caused by laser irradiation, thus the near-infrared (NIR) absorbing vehicles with high photothermal conversion efficiency are demanded in the low power treatment. Herein, the NIR-absorbing agent polydopamine (PDA) and carbon dots (CDs) were gated on the openings of hollow mesoporous carbon (HMC) to construct a photothermal enhanced multi-functional system (HMC-SS-PDA@CDs). Interestingly, the fluorescence emission wavelength of HMC-SS-PDA@CDs was red-shifted by FRET effect between PDA and CDs, which solved the dilemma of fluorescence quenching of carbon-based materials and was more conducive to cell imaging. The modification of PDA@CDs not only acts as the gatekeepers to realize multi-responsive release of pH, GSH and NIR, but also endows the HMC vehicle with excellent photothermal generation capacity, the possibility for bio-imaging as well as the enhanced stability. Naturally, both the cytological level and the multicellular tumor sphere level demonstrate that the delivery system has good low-power synergistic therapeutic with combination index (CI) of 0.348 and imaging effects. Meanwhile, the combined treatment group showed the highest tumor inhibition rate of 92.6% at 0.75 W/cm². Therefore, DOX/HMC-SS-PDA@CDs nano-platform had broad application prospects in low power therapy and convenient imaging of carbon-based materials.

Supramolecular brush polymers prepared from 1,3,4-oxadiazole and cyanobutoxy functionalised pillar[5]arene for detecting Cu2+

The self-assembly of an A1/A2 disubstituted pillar[5]arene was used to construct a supramolecular brush polymer.

Manganese porphyrin-based metal-organic framework for synergistic sonodynamic therapy and ferroptosis in hypoxic tumors

Development of efficient therapeutic strategy to incorporate ultrasound (US)-triggered sonodynamic therapy (SDT) and ferroptosis is highly promising in cancer therapy. However, the SDT efficacy is severely limited by the hypoxia and high glutathione (GSH) in the tumor microenvironment, and ferroptosis is highly associated with reactive oxygen species (ROS) and GSH depletion.

Methods: A manganese porphyrin-based metal-organic framework (Mn-MOF) was constructed as a nanosensitizer to self-supply oxygen (O₂) and decrease GSH for enhanced SDT and ferroptosis. In vitro and in vivo analysis, including characterization, O₂ generation, GSH depletion, ROS generation, lipid peroxidation, antitumor efficacy and tumor immune microenvironment were systematically evaluated.

Results: Mn-MOF exhibited catalase-like and GSH decreasing activity in vitro. After efficient internalization into cancer cells, Mn-MOF persistently catalyzed tumor-overexpressed H₂O₂ to in-situ produce O₂ to relieve tumor hypoxia and decrease GSH and GPX4, which facilitated the formation of ROS and ferroptosis to kill cancer cells upon US irradiation in hypoxic tumors. Thus, strong anticancer and anti-metastatic activity was found in H22 and 4T1 tumor-bearing mice after a single administration of Mn-MOF upon a single US irradiation. In addition, Mn-MOF showed strong antitumor immunity and improved immunosuppressive microenvironment upon US irradiation by increasing the numbers of activated CD8⁺ T cells and matured dendritic cells and decreaing the numbers of myeloid-derived suppressor cells in tumor tissues.

Conclusions: Mn-MOF holds great potential for hypoxic cancer therapy.

Role of Functionalized Pillararene Architectures in Supramolecular Catalysis

The many useful features possessed by pillararenes (PAs; e.g. rigid, capacious, and hydrophobic cavities, as well as exposed functional groups) have led to a tremendous increase in their popularity since their first discovery in 2008. In this Minireview, we emphasize the use of functionalized PAs and their assembled supramolecular materials in the field of catalysis. We aim to provide a fundamental understanding and mechanism of the role PAs play in catalytic process. The topics are subdivided into catalysis promoted by the PA rim/cavity, PA-based nanomaterials, and PA-based polymeric materials. To the best of our knowledge, this is the first overview on PA-based catalysis. This Minireview not only summarizes the fabrications and applications of PAs in catalysis but also anticipates future research efforts in applying supramolecular hosts in catalysis.