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

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.

Supramolecular Chemotherapy with Cucurbit[n]urils as Encapsulating Hosts

The cucurbit[n]urils (CB[n]) belong to the field of relatively young supramolecules which act as containers for a large variety of guests and are being explored extensively for their numerous biomedical applications. This includes drug formulation and delivery, controlled drug release, photodynamic therapy, sensing for bioanalytical purposes, etc. These supramolecular host-guest systems have distinctive recognition properties and have successfully been shown to enhance the in vitro and in vivo utility of various chemotherapeutic agents. The CB[n]s are tailored to optimize their application in payload delivery and diagnostics and in lowering the toxicity of existing drugs. This review has listed the recent studies on working mechanisms and host-guest complexation of the biologically vital molecules with CB[n] and highlighted their implementation in anticancer therapeutics. Various modifications in CB-drug inclusion compounds like CB supramolecular nanoarchitectures along with application in photodynamic therapy, which has shown potential as targeted drug delivery vehicles in cancer chemotherapy, have also been discussed.

Supramolecular Combination Chemotherapy: Cucurbit[8]uril Complex Enhanced Platinum Drug Infiltration and Modified Nanomechanical Property of Colorectal Cancer Cells

Combination chemotherapy is recognized as a vital medical treatment for cancer, but it has not achieved clinical ideal effects of combination therapy. Herein, we designed a supramolecular combination chemotherapy strategy based on cucurbit[8]uril (CB[8]), which can be facilely assembled into dual platinum drugs. Interestingly, employing the CB[8] carrier led to a greater than 10-fold intracellular Pt content compared to that of dual drugs at 4 h, and the CB[8] complex (CLE) can enhance the infiltration of platinum drugs in colorectal tumor cells tremendously. The platinum drugs can be released from CLE through consuming more tumor biomarker spermidine. Through analyzing the nanomechanical property of the colorectal tumor cellular surface by bioscope AFM, it was revealed that CLE modified the property by decreasing the adhesion and increasing the stiffness. This study provided a facile and sensitive strategy for improving combination chemotherapy by supramolecular materials.

Supramolecular Combination Cancer Therapy Based on Macrocyclic Supramolecular Materials

Supramolecular combination therapy adopts supramolecular materials to design intelligent drug delivery systems with different strategies for cancer treatments. Thereinto, macrocyclic supramolecular materials play a crucial role in encapsulating anticancer drugs to improve anticancer efficiency and decrease toxicity towards normal tissue by host-guest interaction. In general, chemotherapy is still common therapy for solid tumors in clinics. However, supramolecular combination therapy can overcome the limitations of the traditional single-drug chemotherapy in the laboratory findings. In this review, we summarized the combination chemotherapy, photothermal chemotherapy, and gene chemotherapy based on macrocyclic supramolecular materials. Finally, the application prospects in supramolecular combination therapy are discussed.

Recent Advances in Fluorescent Methods for Polyamine Detection and the Polyamine Suppressing Strategy in Tumor Treatment

The biogenic aliphatic polyamines (spermine, spermidine, and putrescine) are responsible for numerous cell functions, including cell proliferation, the stabilization of nucleic acid conformations, cell division, homeostasis, gene expression, and protein synthesis in living organisms. The change of polyamine concentrations in the urine or blood is usually related to the presence of malignant tumors and is regarded as a biomarker for the early diagnosis of cancer. Therefore, the detection of polyamine levels in physiological fluids can provide valuable information in terms of cancer diagnosis and in monitoring therapeutic effects. In this review, we summarize the recent advances in fluorescent methods for polyamine detection (supramolecular fluorescent sensing systems, fluorescent probes based on the chromophore reaction, fluorescent small molecules, and fluorescent nanoparticles). In addition, tumor polyamine-suppressing strategies (such as polyamine conjugate, polyamine analogs, combinations that target multiple components, spermine-responsive supramolecular chemotherapy, a combination of polyamine consumption and photodynamic therapy, etc.) are highlighted. We hope that this review promotes the development of more efficient polyamine detection methods and provides a comprehensive understanding of polyamine-based tumor suppressor strategies.

Application of Approved Cisplatin Derivatives in Combination Therapy against Different Cancer Diseases

The problems with anticancer therapy are resistance and toxicity. From 3000 Cisplatin derivatives tested as antitumor agents, most of them have been rejected, due to toxicity. The aim of current study is the comparison of therapeutic combinations of the currently applied in clinical practice: Cisplatin, Carboplatin, Oxaliplatin, Nedaplatin, Lobaplatin, Heptaplatin, and Satraplatin. The literature data show that the strategies for the development of platinum anticancer agents and bypassing of resistance to Cisplatin derivatives and their toxicity are: combination therapy, Pt IV prodrugs, the targeted nanocarriers. The very important strategy for the improvement of the antitumor effect against different cancers is synergistic combination of Cisplatin derivatives with: (1) anticancer agents—Fluorouracil, Gemcitabine, Cytarabine, Fludarabine, Pemetrexed, Ifosfamide, Irinotecan, Topotecan, Etoposide, Amrubicin, Doxorubicin, Epirubicin, Vinorelbine, Docetaxel, Paclitaxel, Nab-Paclitaxel; (2) modulators of resistant mechanisms; (3) signaling protein inhibitors—Erlotinib; Bortezomib; Everolimus; (4) and immunotherapeutic drugs—Atezolizumab, Avelumab, Bevacizumab, Cemiplimab, Cetuximab, Durvalumab, Erlotinib, Imatinib, Necitumumab, Nimotuzumab, Nivolumab, Onartuzumab, Panitumumab, Pembrolizumab, Rilotumumab, Trastuzumab, Tremelimumab, and Sintilimab. An important approach for overcoming the drug resistance and reduction of toxicity of Cisplatin derivatives is the application of nanocarriers (polymers and liposomes), which provide improved targeted delivery, increased intracellular penetration, selective accumulation in tumor tissue, and enhanced therapeutic efficacy. The advantages of combination therapy are maximum removal of tumor cells in different phases; prevention of resistance; inhibition of the adaptation of tumor cells and their mutations; and reduction of toxicity.

Supramolecular co-encapsulation of a photosensitizer and chemotherapeutic drug in cucurbit[8]uril for potential chemophototherapy

Supramolecular strategies as well as combinatorial approaches have been proposed to improve cancer therapeutics. In this work, we investigated the encapsulation of the photosensitizer acridine orange (AO) and the chemotherapeutic drug oxaliplatin (OxPt) in cucurbit[8]uril (CB[8]), and tested their effect both separate and combined on tumoral cells cultivated in vitro. Binding constants and enthalpies of reaction for the AO@CB[8], (AO)₂@CB[8] and OxPt@CB[8] complexes were determined by isothermal titration calorimetry. In the case of AO, a negative cooperativity for the binding of the second AO molecule was found, in agreement with previous fluorescence titration data. We show herein that the AO@CB[8] complex was effectively incorporated within the cells and showed important phototoxicity, while the OxPt@CB[8] complex was cytotoxic only at long incubation times (24 h). Pre-treatment of the cells with the OxPt@CB[8] complex for 24 h inhibited any photodynamic action by the later treatment with the AO@CB[8] complex. However, when both complexes were co-incubated for 90 min, the combined cytotoxicity/phototoxicity was superior to any of the treatments individually. A cooperative effect was identified that added up to an extra 30% cytotoxicity/phototoxicity. The results point to an interesting system where a photosensitizer and chemotherapeutic drug are co-encapsulated in a macrocycle to develop chemophototherapy applications.

Supramolecular Chemotherapy: Noncovalent Bond Synergy of Cucurbit[7]uril against Human Colorectal Tumor Cells

Supramolecular chemotherapy has drawn increasing interest due to its ability to improve the efficiency of antitumor drugs and fewer associated toxic side effects. In this study, the smart supramolecular cargo, the doxorubicin-ZnO-cucurbit[7]uril (CDZ) nanocomplex, was constructed through ion-dipole interactions between cucurbit[7]uril {CB[7]} and doxorubicin-ZnO (dox-ZnO). The binding affinity of CB[7] and dox-ZnO was determined to be 10⁴ M^-1 by isothermal titration calorimetry. Importantly, spermine had a stronger binding affinity (10⁶ M^-1) with CB[7] than dox-ZnO through host-guest interactions. In the tumor microenvironment, spermine disassembled the CDZ nanocomplex, and dox was released from the nanocomplex by XRD, UV-visible spectra, and contact angle analysis. Compared to the single drug dox, the CDZ nanocomplex was demonstrated to possess higher activity of killing colorectal tumor cells by confocal laser scanning microscopy and cytotoxicity, which could be attributed to spermine concentration, spermine synthase, free radical damage, and G₁ cell cycle arrest. Overall, the supramolecular delivery of dox can enhance the inhibition of human colorectal tumor cell proliferation and reduce cytotoxicity in human myocardial cells through the noncovalent bond synergy of {CB[7]}.