A host-guest drug delivery nanosystem for supramolecular chemotherapy

A spermine-responsive supramolecular chemotherapy system constructed from a water-soluble pillar[5]arene and a diphenylanthracene-containing amphiphile for precise chemotherapy

Stimuli-responsive supramolecular chemotherapy, particularly in response to cancer biomarkers, has emerged as a promising strategy to overcome the limitations associated with traditional chemotherapy. Spermine (SPM) is known to be overexpressed in certain cancers. In this study, we introduced a novel supramolecular chemotherapy system triggered by SPM. The system featured pyridine salts of a diphenylanthracene derivative (PyEn) and a complementary water-soluble pillar[5]arene (WP5C5) with long alkyl chains. The diphenylanthracene unit of PyEn is effectively encapsulated within the long alkyl chains of WP5C5, resulting in a substantial reduction in the cytotoxicity of PyEn towards normal cells. The therapeutic effect of PyEn is selectively triggered intracellularly through SPM, leading to the endosomal release of PyEn and concurrent in situ cytotoxicity. This supramolecular chemotherapy system exhibits notable tumor inhibition against SPM-overexpressed cancers with reduced side effects on normal tissues. The supramolecular strategy for intracellular activation provides a novel tool with potential applications in chemotherapeutic interventions, offering enhanced selectivity and reduced cytotoxicity to normal cells.

Co-Assembled Nanoparticles toward Multi-Target Combinational Therapy of Alzheimer's Disease by Making Full Use of Molecular Recognition and Self-Assembly

The complex pathologies in Alzheimer's disease (AD) severely limit the effectiveness of single-target pharmic interventions, thus necessitating multi-pronged therapeutic strategies. While flexibility is essentially demanded in constructing such multi-target systems, for achieving optimal synergies and also accommodating the inherent heterogeneity within AD. Utilizing the dynamic reversibility of supramolecular strategy for conferring sufficient tunability in component substitution and proportion adjustment, amphiphilic calixarenes are poised to be a privileged molecular tool for facilely achieving function integration. Herein, taking β-amyloid (Aβ) fibrillation and oxidative stress as model combination pattern, a supramolecular multifunctional integration is proposed by co-assembling guanidinium-modified calixarene with ascorbyl palmitate and loading dipotassium phytate within calixarene cavity. Serial pivotal events can be simultaneously addressed by this versatile system, including 1) inhibition of Aβ production and aggregation, 2) disintegration of Aβ fibrils, 3) acceleration of Aβ metabolic clearance, and 4) regulation of oxidative stress, which is verified to significantly ameliorate the cognitive impairment of 5×FAD mice, with reduced Aβ plaque content, neuroinflammation, and neuronal apoptosis. Confronted with the extremely intricate clinical realities of AD, the strategy presented here exhibits ample adaptability for necessary alterations on combinations, thereby may immensely expedite the advancement of AD combinational therapy through providing an exceptionally convenient platform.

Alleviating Recombinant Tissue Plasminogen Activator-induced Hemorrhagic Transformation in Ischemic Stroke via Targeted Delivery of a Ferroptosis Inhibitor

Intravenous thrombolysis with recombinant tissue plasminogen activator (rtPA) is the primary treatment for ischemic stroke. However, rtPA treatment can substantially increase blood-brain barrier (BBB) permeability and susceptibility to hemorrhagic transformation. Herein, the mechanism underlying the side effects of rtPA treatment is investigated and demonstrated that ferroptosis plays an important role. The ferroptosis inhibitor, liproxstatin-1 (Lip) is proposed to alleviate the side effects. A well-designed macrocyclic carrier, glucose-modified azocalix[4]arene (GluAC4A), is prepared to deliver Lip to the ischemic site. GluAC4A bound tightly to Lip and markedly improved its solubility. Glucose, modified at the upper rim of GluAC4A, imparts BBB targeting to the drug delivery system owing to the presence of glucose transporter 1 on the BBB surface. The responsiveness of GluAC4A to hypoxia due to the presence of azo groups enabled the targeted release of Lip at the ischemic site. GluAC4A successfully improved drug accumulation in the brain, and Lip@GluAC4A significantly reduced ferroptosis, BBB leakage, and neurological deficits induced by rtPA in vivo. These findings deepen the understanding of the side effects of rtPA treatment and provide a novel strategy for their effective mitigation, which is of great significance for the treatment and prognosis of patients with ischemic stroke.

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.

Active targeting tumor therapy using host-guest drug delivery system based on biotin functionalized azocalix[4]arene

Host-guest drug delivery systems (HGDDSs) provided a facile method for incorporating biomedical functions, including efficient drug-loading, passive targeting, and controlled drug release. However, developing HGDDSs with active targeting is hindered by the difficult functionalization of popular macrocycles. Herein, we report an active targeting HGDDS based on biotin-modified sulfonated azocalix[4]arene (Biotin-SAC4A) to efficiently deliver drug into cancer cells for improving anti-tumor effect. Biotin-SAC4A was synthesized by amide condensation and azo coupling. Biotin-SAC4A demonstrated hypoxia responsive targeting and active targeting through azo and biotin groups, respectively. DOX@Biotin-SAC4A, which was prepared by loading doxorubicin (DOX) in Biotin-SAC4A, was evaluated for tumor targeting and therapy in vitro and in vivo. DOX@Biotin-SAC4A formulation effectively killed cancer cells in vitro and more efficiently delivered DOX to the lesion than the similar formulation without active targeting. Therefore, DOX@Biotin-SAC4A significantly improved the in vivo anti-tumor effect of free DOX. The facilely prepared Biotin-SAC4A offers strong DOX complexation, active targeting, and hypoxia-triggered release, providing a favorable host for effective breast cancer chemotherapy in HGDDSs. Moreover, Biotin-SAC4A also has potential to deliver agents for other therapeutic modalities and diseases.

Supramolecular Chemotherapy: Complexation by Carboxylated Pillar[6]arene for Decreasing Cytotoxicity of Nitrogen Mustard to Normal Cells and Enhancing Its Antitumor Efficiency against Breast Cancer

Advances in chemotherapeutic strategies are urgently required to improve antitumor efficiency. Herein, a carboxylated pillar[6]arene (CP6A) was employed to load chemotherapy medication, nitrogen mustard (NM), via forming a direct host-guest complex, as this helps to decrease the cytotoxicity of NM on normal mammary epithelial cells. Attributed to the stronger complexation ability of CP6A for endogenous spermine (SPM) than for NM, the complexed NM could be competitively released from the CP6A cavity via replacement with SPM. This chemotherapy strategy performed well in vitro and in vivo for SPM-overexpressed cancers. In comparison with free NM, antitumor efficiency of NM/CP6A was significantly enhanced, which originated from the synergistic effect of competitive release of NM and simultaneous trapping of SPM. This strategy might guide expansion to other first-line antitumor agents to improve therapeutic efficacy and decrease side effects, thereby replenishing the possibilities of supramolecular chemotherapy.

Molecular Recognition with Macrocyclic Receptors for Application in Precision Medicine

Macrocyclic receptors can serve as alternatives to natural recognition systems as recognition tools. They provide effectively preorganized cavities to encapsulate guests via host-guest interactions, thereby affecting the physiochemical properties of the guests. Macrocyclic receptors exhibit chemical and thermal stabilities higher than those of natural receptors and thus are expected to resist degradation inside the body. This reduces the risk of harmful degradation byproducts and ensures optimal levels of effectiveness. Macrocyclic receptors have precise molecular weights and well-defined structures; this ensures their batch-to-batch reproducibility, which is critical for ensuring quality and effectiveness levels. Moreover, macrocyclic receptors exhibit broad modification tunabilities, rendering them adaptable to various guests. Molecular recognition is the basis of numerous biological processes. Macrocyclic receptors may display considerable potential for application in diagnosing and treating diseases, depending on the host-guest recognition of bioactive molecules. However, the binding affinities and selectivities of macrocyclic receptors toward bioactive molecules are generally insufficient, which may lead to problems such as low diagnosis accuracies, off-target leaking, and interference with normal functions. Therefore, addressing the challenge of the strong and specific complexation of bioactive molecules and macrocyclic receptors is imperative.To overcome this challenge, we proposed the innovative strategies of longitudinal cavity extension and coassembled heteromultivalent recognition for application in the recognition of small molecules and biomacromolecules, respectively. The deepened cavity provides a stronger hydrophobic effect and a larger interaction area while maintaining the framework rigidity. By coassembling two macrocyclic amphiphiles into one ensemble, we achieved the desired heteromultivalent recognition. This strategy affords the necessary binding properties while preventing the requirement of tedious steps and site mismatch in covalent synthesis. Using these two strategies, we achieved specific and strong binding of macrocyclic receptors to various bioactive molecules including biomarkers, drugs, and disease-related peptides/proteins. We then applied these macrocyclic receptor-based recognition systems in biosensing and bioimaging, drug delivery, and therapeutics.In this Account, we summarize the strategies we used in the recognition of small molecules and biomacromolecules. Thereafter, we discuss their applications in precision medicine, involving the (1) sensing of biomarkers and imaging of lesion sites, which are critical in the early screening of diseases and accurate diagnoses; (2) precise loading and targeted delivery of drugs, which are crucial in improving their therapeutic efficacies and reducing their side effects; and (3) capture and removal of disease-related biomacromolecules, which are significant for precise intervention in life processes. Finally, we propose recommendations for the further development of macrocyclic receptor-based recognition systems in biomedicine. Macrocyclic receptors exhibit considerable potential for research, and continued investigation may not only expand the applications of supramolecular chemistry but also open novel avenues for the development of precision medicine.

Supramolecular host-guest nanosystems for overcoming cancer drug resistance

Cancer drug resistance has become one of the main challenges for the failure of chemotherapy, greatly limiting the selection and use of anticancer drugs and dashing the hopes of cancer patients. The emergence of supramolecular host-guest nanosystems has brought the field of supramolecular chemistry into the nanoworld, providing a potential solution to this challenge. Compared with conventional chemotherapeutic platforms, supramolecular host-guest nanosystems can reverse cancer drug resistance by increasing drug uptake, reducing drug efflux, activating drugs, and inhibiting DNA repair. Herein, we summarize the research progress of supramolecular host-guest nanosystems for overcoming cancer drug resistance and discuss the future research direction in this field. It is hoped that this review will provide more positive references for overcoming cancer drug resistance and promoting the development of supramolecular host-guest nanosystems.

Novel biotin-linked amphiphilic calix[4]arene-based supramolecular micelles as doxorubicin carriers for boosted anticancer activity

Supramolecular carrier-mediated chemotherapy is a highly attractive strategy for targeted drug delivery. In this study, four novel biotin-linked calix[4]arenes BPCA1-BPCA4 have been rationally designed to construct nano-complex with doxorubicin. The in vitro and in vivo assessments reveal that BPCA4-DOX with excellent stability are capable of affording significantly superior anti-tumor activity and lower side effects.

Stimuli-Responsive Codelivery System Self-Assembled from in Situ Dynamic Covalent Reaction of Macrocyclic Disulfides for Cancer Magnetic Resonance Imaging and Chemotherapy

Supramolecular self-assembly has gained increasing attention to construct multicomponent drug delivery systems for cancer diagnosis and therapy. Despite that these self-assembled nanosystems present surprising properties beyond that of each subcomponent, the spontaneous nature of co-self-assembly causes significant difficulties in control of the synthesis process and consequently leads to unsatisfactory influences in downstream applications. Hence, we utlized an in situ dynamic covalent reaction based on thiol-disulfide exchange to slowly produce disulfide macrocycles, which subsequently triggered the co-self-assembly of an anticancer drug (doxorubicin, DOX) and a magnetic resonance imaging (MRI) contrast agent of ultrasmall iron oxide nanoparticles (IO NPs). It showed concentration regulation of macrocyclic disulfides, DOX, and IO NPs by a dynamic covalent self-assembly (DCS) strategy, resulting in a stable codelivery nanosystem with high drug loading efficiency of 37.36%. More importantly, disulfide macrocycles in the codelivery system could be reduced and broken by glutathione (GSH) in tumor cells, thus leading to disassembly of nanostructures and intellgent release of drugs. These stimuli-responsive performances have been investigated via morphologies and molecular structures, revealing greatly enhanced dual-modal MRI abilities and smart drug release under the trigger of GSH. Moreover, the codelivery system conjugated with a targeting molecule of cyclic Arg-Gly-Asp (cRGD) exhibited significant biocompatibility, MR imaging, and chemotherapeutic anticancer effect in vitro and in vivo. These results indicated that in situ dynamic covalent chemistry enhanced the control over co-self-assembly and paved the way to develop more potential drug delivery systems.

Supramolecular nanomedicines based on host-guest interactions of cyclodextrins

In the biomedical and pharmaceutical fields, cyclodextrin (CD) is undoubtedly one of the most frequently used macrocyclic compounds as the host molecule because it has good biocompatibility and can increase the solubility, bioavailability, and stability of hydrophobic drug guests. In this review, we generalized the unique properties of CDs, CD-related supramolecular nanocarriers, supramolecular controlled release systems, and targeting systems based on CDs, and introduced the paradigms of these nanomedicines. In addition, we also discussed the prospects and challenges of CD-based supramolecular nanomedicines to facilitate the development and clinical translation of these nanomedicines.

Using host-guest interactions at the interface of quantum dots to load drug molecules for biocompatible, safe, and effective chemo-photodynamic therapy against cancer

Combining photodynamic therapy (PDT) and chemotherapy (CHT) by loading an anti-cancer drug and a photosensitizer (PS) into the same delivery nanosystem has been proposed as an effective approach to achieve synergistic effects for a safe cancer treatment. However, exploring an ideal delivery nanosystem has been challenging, because the noncovalent interactions must be maintained between the multiple components to produce a stable yet responsive nanostructure that takes into account the encapsulation of drug molecules. We addressed this issue by engineering the interfacial interaction between Ag₂S quantum dots (QDs) using a pillararene derivative to direct the co-self-assembly of the entire system. The high surface area-to-volume ratio of the Ag₂S QDs provided ample hydrophobic space to accommodate the anti-drug molecule doxrubicine. Moreover, Ag₂S QDs served as PSs triggered by 808 nm near-infrared (NIR) light and also as carriers for high-efficiency delivery of drug molecules to the tumor site. Drug release experiments showed smart drug release under the acidic microenvironments (pH 5.5) in tumor cells. Additionally, the Ag₂S QDs demonstrated outstanding PDT ability under NIR light, as confirmed by extracellular and intracellular reactive oxygen species generation. Significant treatment efficacy of the chemo-photodynamic synergistic therapy for cancer using the co-delivery system was demonstrated via in vitro and in vivo studies. These findings suggest that our system offers intelligent control of CHT and PDT, which will provide a promising strategy for constructing hybrid systems with synergistic effects for advanced applications in biomedicine, catalysis, and optoelectronics.

Preparation and Characterization of Insecticide/Calix[4]arene Complexes and Their Enhanced Insecticidal Activities against Plutella xylostella

Applications of supramolecular materials in plant protection have attracted significant interest in recent years. To develop a feasible method to improve the efficacy and reduce the usage of chemical pesticides, the effect of calix[4]arene (C4A) inclusion on enhancing the insecticidal activity of commercial insecticides was investigated. Results showed that all three tested insecticides (chlorfenapyr, indoxacarb, and abamectin) with distinct molecular sizes and modes of action were able to form stable 1:1 host-guest complexes with C4A through simple preparation steps. The insecticidal activities of the complexes against Plutella xylostella were effectively enhanced compared to the guest molecule, with the synergism ratio being up to 3.05 (for indoxacarb). An obvious correlation was found between the enhanced insecticidal activity and the high binding affinity between insecticide and C4A, while the improvement in water solubility may not be a determining factor. The work would provide hints for the further development of functional supramolecular hosts as synergists in pesticide formulations.

Reversible covalent nanoassemblies for augmented nuclear drug translocation in drug resistance tumor

The drug efflux by P-glycoprotein (P-gp) is the primary contributor of multidrug resistance (MDR), which eventually generates insufficient nuclear drug accumulation and chemotherapy failure. In this paper, reversible covalent nanoassemblies on the basis of catechol-functionalized methoxy poly (ethylene glycol) (mPEG-dop) and phenylboronic acid-modified cholesterol (Chol-PBA) are successfully synthesized for delivery of both doxorubicin (DOX, anti-cancer drug) and tariquidar (TQR, P-glycoprotein inhibitor), which shows efficient nuclear DOX accumulation for overcoming tumor MDR. Through naturally forming phenylboronate linkage in physiological circumstances, Chol-PBA is able to bond with mPEG-dop. The resulting conjugates (PC) could self-assemble into reversible covalent nanoassemblies by dialysis method, and transmission electron microscopy analysis reveals the PC distributes in nano-scaled spherical particles before and after drug encapsulation. Under the assistance of Chol, PC can enter into lysosome of tumor cells via low-density lipoprotein (LDL) receptor-mediated endocytosis. Then the loaded TQR and DOX are released in acidic lysosomal compartments, which inhibit P-gp mediated efflux and elevate nuclear accumulation of DOX, respectively. At last, this drug loaded PC nanoassemblies show significant tumor suppression efficacy in multidrug-resistant tumor models, which suggests great potential for addressing MDR in cancer therapy.

Supramolecular Biopharmaceutical Carriers Based on Host-Guest Interactions

Traditional drugs have the disadvantages of poor permeability and low solubility, which makes the utilization of pesticides lower and brings many side effects. With the continuous development of supramolecular chemistry in recent years, it has also played an irreplaceable role in the field of pharmaceutical science. Supramolecular macrocycles, such as crown ethers, cyclodextrins, calixarenes, pillararenes and cucurbiturils, are potentially good candidates for drug carriers due to their biocompatibility, hydrophobic cavity and ease of derivatization. The encapsulation of drugs based on host-guest interaction has the advantage of being adjustable and reversible as well as improving the low availability of drugs. Here, the recent advances in methods and strategies for drug encapsulation and release based on supramolecular macrocycles with host-guest interactions have been systematically summarized, laying a bright foundation for the development of novel nanopesticide preparations in the future and pointing out future directions of novel biopesticide research.

Drug in Drug: A Host-Guest Formulation of Azocalixarene with Hydroxychloroquine for Synergistic Anti-Inflammation

Macrocyclic delivery and therapeutics are two significant topics in supramolecular biomedicine. The functional integration of these topics would open new avenues for treating diseases synergistically. However, these two individual topics have only been occasionally merged, probably because of the lack of functionalized design of macrocyclic host and the lack of efficient recognition between host and guest drugs. Herein, a "drug-in-drug" strategy is proposed, in which an active drug is encapsulated by a macrocycle possessing therapeutic activity to form a multifunctional supramolecular active pharmaceutical ingredient. As a proof-of-concept, a complex of hydroxychloroquine (HCQ) with sulfonated azocalix[4]arene (HCQ@SAC4A) is prepared to treat rheumatoid arthritis (RA) in a combined fashion. SAC4A is a therapeutic agent that exhibits scavenging capacity for reactive oxygen species and exerts an anti-inflammatory effect. It is also a hypoxia-responsive carrier that can deliver HCQ directly to the inflammatory articular cavity. Consequently, HCQ@SAC4A achieves the synergistic anti-inflammatory effect on both inflamed RAW 264.7 cells and RA rats. This effect is attributed to the temporal and spatial consistency of the two active ingredients of the complex. As a new paradigm for combinational therapy, the drug-in-drug strategy advances in easy preparation, mix-and-match combination, and precise ratiometric control.

A Calixarene Assembly Strategy of Combined Anti-Neuroinflammation and Drug Delivery Functions for Traumatic Brain Injury Therapy

Excessive inflammatory reaction aggravates brain injury and hinders the recovery of neural function in nervous system diseases. Microglia, as the major players of neuroinflammation, control the progress of the disease. There is an urgent need for effective non-invasive therapy to treat neuroinflammation mediated by microglia. However, the lack of specificity of anti-inflammatory agents and insufficient drug dose penetrating into the brain lesion area are the main problems. Here, we evaluated a series of calixarenes and found that among them the self-assembling architecture of amphiphilic sulfonatocalix[8]arene (SC8A12C) had the most potent ability to suppress neuroinflammation in vitro and in vivo. Moreover, SC8A12C assemblies were internalized into microglia through macropinocytosis. In addition, after applying the SC8A12C assemblies to the exposed brain tissue, we observed that SC8A12C assemblies penetrated into the brain parenchyma and eliminated the inflammatory factor storm, thereby restoring neurobiological functions in a mouse model of traumatic brain injury.

Recent Updates on Supramolecular-Based Drug Delivery - Macrocycles and Supramolecular Gels

Supramolecules-based drug delivery has attracted significant recent research attention as it could enhance drug solubility, retention time, targeting, and stimuli responsiveness. Among the different supramolecules and assemblies, the macrocycles and the supramolecular hydrogels are the two important categories investigated to a greater extent. Here, we provide the most recent advancements in these categories. Under macrocycles, reports on drug delivery by cyclodextrins, cucurbiturils, calixarenes/pillararenes, crown ethers and porphyrins are detailed. The second category discusses the supramolecular hydrogels of macrocycles/polymers and low molecular weight gelators. The updated information provided could be helpful to advance R & D in this vital area.

Supramolecular Radiosensitizer Based on Hypoxia-Responsive Macrocycle

Radiotherapy (RT) has been viewed as one of the most effective and extensively applied curatives in clinical cancer therapy. However, the radioresistance of tumor severely discounts the radiotherapy outcomes. Here, an innovative supramolecular radiotherapy strategy, based on the complexation of a hypoxia-responsive macrocycle with small-molecule radiosensitizer, is reported. To exemplify this tactic, a carboxylated azocalix[4]arene (CAC4A) is devised as molecular container to quantitatively package tumor sensitizer banoxantrone dihydrochloride (AQ4N) through reversible host-guest interaction. Benefited from the selective reduction of azo functional groups under hypoxic microenvironment, the supramolecular prodrug CAC4A•AQ4N exhibits high tumor accumulation and efficient cellular internalization, thereby significantly amplifying radiation-mediated tumor destruction without appreciable systemic toxicity. More importantly, this supramolecular radiotherapy strategy achieves an ultrahigh sensitizer enhancement ratio (SER) value of 2.349, which is the supreme among currently reported noncovalent-based radiosensitization approach. Further development by applying different radiosensitizing drugs can make this supramolecular strategy become a general platform for boosting therapeutic effect in cancer radiotherapies, tremendously promising for clinical translation.

Supramolecular Drug Delivery System from Macrocycle-Based Self-Assembled Amphiphiles for Effective Tumor Therapy

Intelligent drug delivery systems (DDSs) that can improve therapeutic outcomes of antitumor agents and decrease their side effects are urgently needed to satisfy special requirements of treatment of malignant tumors in clinics. Here, the fabrication of supramolecular self-assembled amphiphiles based on the host-guest recognition between a cationic water-soluble pillar[6]arene (WP6A) host and a sodium decanesulfonate guest (G) is reported. The chemotherapeutic agent doxorubicin hydrochloride (DOX) can be encapsulated into the formed vesicle (G/WP6A) to construct supramolecular DDS (DOX@G/WP6A). WP6A affords strong affinities to G to avoid undesirable off-target leakage during delivery. Nanoscaled DOX@G/WP6A is capable of preferentially accumulating in tumor tissue via enhanced permeability and retention (EPR) effect. After internalization by tumor cells, the abundant adenosine triphosphate (ATP) binds competitively with WP6A to trigger the disintegration of self-assembled vesicles with the ensuing release of DOX. In vitro and in vivo research confirmed that DOX@G/WP6A is not only able to promote antitumor efficacy but also reduce DOX-related systemic toxicity. The above favorable findings are ascribed to the formation of ternary self-assembly, which profits from the combination of the factors of the EPR effect and the ATP-triggered release.

Glutathione sensitive vesicles prepared from supramolecular amphiphiles

Glutathione (GSH) sensitive vesicles were prepared by the self-assembly of amphiphilic inclusion complexes. These novel chemically sensitive supramolecular amphiphiles are anticipated to have applications in drug delivery; the nanocarriers can protect the encapsulated cargo and release it via triggered degradation in high concentrations of GSH. Additionally, the sensitivity of the vesicles to GSH indicates that the dynamic covalent disulfide bond at the vesicle surface can be used for post-modification of the nanocarrier via a thiol-disulfide exchange, a strategy that can be exploited to introduce targeting moieties to increase treatment specificity. Supramolecular amphiphiles containing a dynamic covalent disulfide bond were prepared via the host-guest inclusion complexes between alkylated β-cyclodextrin (β-CD) hosts and adamantane terminated polyethylene glycol derivatives. The significant difference between the critical micelle concentrations of the supramolecular amphiphiles and the individual host and guest components confirmed that a unique supramolecular amphiphile was formed. Fluorescence experiments and dynamic light scattering (DLS) revealed that the supramolecular amphiphiles self-assembled into vesicles of 130 nm diameter which were stable for 8 months. Degradation of the vesicles after incubation with GSH was monitored using DLS and by the release of encapsulated 5,6-carboxyfluorescein (CF), observed by an increase in fluorescence intensity. Degradation of the nanocarrier was faster at intracellular GSH concentrations than at extracellular GSH concentrations.

Glycocalixarene with luminescence for Warburg effect-mediated tumor imaging and targeted drug delivery

Fluorescently labeled calix[4]arene glycoconjugates demonstrate multifunctional potential in both Warburg effect mediated tumor imaging and GLUT1 targeted drug delivery. Nitrobenzoxadiazole and mannose conjugated NBD-Man-CA was found to be selectively recognized by GLUT1 and act as a "molecular carrier" for selective tumor targeting.

Supramolecular imaging of spermine in cancer cells

As an important biomarker, the overexpressed spermine has been widely investigated for cancer diagnosis and treatment. However, bioimaging of spermine in living cells is still a formidable challenge. Herein, we design a supramolecular imaging ensemble for spermine by the host-guest complexation of amphiphilic sulfonatocalix[5]arene (SC5A12C) assembly with lucigenin (LCG). Strong binding ability and complexation-induced fluorescence quenching properties enable SC5A12C to quench the fluorescence of LCG dramatically and to recover it completely due to the competition of overexpressed spermine in cancer cells. SC5A12C also exhibits excellent biocompatibility and promotes cellular uptake due to its ability to form ultra-stable assembly. Co-assembling folate further promotes the cellular uptake of folate receptor overexpressed cancer cells, contributing to enhanced bioimaging.

Supramolecular Bioimaging through Signal Amplification by Combining Indicator Displacement Assay with Förster Resonance Energy Transfer

Fluorescent chemosensors are powerful imaging tools in the fields of life sciences and engineering. Based on the principle of supramolecular chemistry, indicator displacement assay (IDA) provides an alternative approach for constructing and optimizing chemosensors, which has the advantages of simplicity, tunability, and modularity. However, the application of IDA in bioimaging continues to face a series of challenges, including interfering signals, background noise, and inconsistent spatial location. Accordingly, we herein report a supramolecular bioimaging strategy of Förster resonance energy transfer (FRET)-assisted IDA by employing macrocyclic amphiphiles as the operating platform. By merging FRET with IDA, the limitations of IDA in bioimaging were addressed. As a proof of concept, the study achieved mitochondria-targeted imaging of adenosine triphosphate in live cells with signal amplification. This study opens a non-covalent avenue for bioimaging with advancements in tunability, generality, and simplicity, apart from the covalent approach.

The supramolecularly complexes of calix[4]arene derivatives toward favipiravir antiviral drug (used to treatment of COVID-19): a DFT study on the geometry optimization, electronic structure and infrared spectroscopy of adsorption and sensing

While the world is in search of a vaccine that can cure COVID-19 disease, favipiravir is the most commonly used antiviral drug in the treatment of patients during the pandemic process. In this study, we investigated the host-guest interaction between the popular supramolecule calix[4]arene derivatives and the favipiravir drug by using the DFT (Density Functional Theory) method. The B3LYP hybrid method and 6-31G (d,p) basis set were utilized to determine the optimized structures of the host and guest molecules and their complexes. The negative adsorption energy (∆E) and adsorption enthalpy (∆H) calculated for the complexes formed between calix[4]arene compounds and favipiravir drug molecule mentioned that adsorption of favipiravir molecule was an exothermic process on calix[4]arene structures. On the other hand, among the calixarene derivatives in the study, Gibbs free energy change (∆G) value for the adsorption was only negative on calix[4]arene4 molecule. The infrared spectroscopy (IR) calculations were performed by examining the C=O, O-H and NH2 vibrational frequencies to see the adsorption behavior in the favipiravir-calix[4]arene complex. After adsorption of the favipiravir molecule, HOMO-LUMO gap values decreased significantly for the structures and therefore electrical conductivity increased proportionally. In addition, sensor response factors, Fermi energy levels and workfunction changes of calix[4]arene derivatives were calculated and examined. Charge transfer between the four calix[4]arene compounds and the favipiravir molecule has occurred after adsorption. This attributes that calix[4]arene derivatives can be used as a well-suited favipiravir sensor (electronic and workfunction) and adsorbent at room temperature. Based on the calculations made to see the solvent effect on the adsorption of favipiravir it was determined that it did not affect the interaction between the drug molecule and the calix[4]arene compound too much and the adsorption energy turned into a slightly less negative value.

Supramolecular Chemotherapy: Host-Guest Complexes of Heptaplatin-Cucurbit[7]uril toward Colorectal Normal and Tumor Cells

Supramolecular chemotherapy is a strategy that is currently used to improve the therapeutic efficacy of traditional chemotherapy while mitigating side effects. Heptaplatin, a platinum chemotherapeutic antitumor drug in colorectal tumors, is traditionally used in the clinic. However, its side effects and low efficiency in killing tumors remain unresolved. Herein, a facile supramolecular chemotherapy platform on account of the host-guest chemistry between cucurbit[7]uril and the commercially available heptaplatin was studied. At pH 7.4, heptaplatin showed a strong binding to the cucurbit[7]uril nanocarrier by ¹H NMR, whose K_a was (1.38 ± 0.06) × 10⁶ M^-1 by isothermal titration calorimetry (ITC). At pH 6.0 in a tumor microenvironment, overexpressed spermine can exchange competitively heptaplatin from heptaplatin-CB[7]. This supramolecular complex achieved higher antitumor activity on colorectal tumor cells and lower cytotoxicity than the drug alone on colorectal normal cells. Furthermore, the antitumor mechanisms of supramolecular complex were investigated by apoptosis, cell cycle, and spermine synthase. It was found that heptaplatin-CB[7] consumed more colorectal tumorous intracellular spermine by the spermine synthase assay (413.85 ± 0.004 pg/mL); hepataplatin-CB[7] caused early apoptosis (87.73%) of colorectal tumor cells; heptaplatin-CB[7] induced an inhibitory response in the G₁ phase of the tumor cell cycle. These findings demonstrated that heptaplatin-CB[7] had higher antitumor activity toward human colorectal tumor cells but lower cytotoxicity toward human colorectal normal cells. It is expected to promote the supramolecular chemotherapy and translational development of the nanocomplex into the clinical field.