Supramolecular Drug-Drug Complex Vesicles Enable Sequential Drug Release for Enhanced Combination Therapy

Supramolecular 3 in 1: A Lubrication and Co-Delivery System for Synergistic Advanced Osteoarthritis Therapy

The complexity, heterogeneity, and drug resistance of diseases necessitate a shift in therapeutic paradigms from monotherapy to combination therapy, which could augment treatment efficiency. Effective treatment of advanced osteoarthritis (OA) requires addressing three key factors contributing to its deterioration: chronic joint inflammation, lubrication dysfunction, and cartilage-tissue degradation. Herein, we present a supramolecular nanomedicine of multifunctionality via molecular recognition and self-assembly. The employed macrocyclic carrier, zwitterion-modified cavitand (CV-2), not only accurately loads various drugs but also functions as a therapeutic agent with lubricating properties for the treatment of OA. Kartogenin (KGN), a drug for articular cartilage regeneration and protection, and flurbiprofen (FP), an anti-inflammatory agent, were coloaded onto CV-2 assembly, forming a supramolecular nanomedicine KGN&FP@CV-2. The three-in-one combination therapy of KGN&FP@CV-2 addresses the three pathological features for treating OA collectively, and thus provides long-term therapeutic benefits for OA through sustained drug release and intrinsic lubrication in vivo. The multifunctional integration of macrocyclic delivery and therapeutics provides a simple, flexible, and universal platform for the synergistic treatment of diseases involving multiple drugs.

Progressive enhanced photodynamic therapy and enhanced chemotherapy fighting against malignant tumors with sequential drug release

During the process of malignant tumor treatment, photodynamic therapy (PDT) exerts poor efficacy due to the hypoxic environment of the tumor cells, and long-time chemotherapy reduces the sensitivity of tumor cells to chemotherapy drugs due to the presence of drug-resistant proteins on the cell membranes for drug outward transportation. Therefore, we reported a nano platform based on mesoporous silica coated with polydopamine (MSN@PDA) loading PDT enhancer MnO2, photosensitizer indocyanine green (ICG) and chemotherapeutic drug doxorubicin (DOX) (designated as DMPIM) to achieve a sequential release of different drugs to enhance treatment of malignant tumors. MSN was first synthesized by a template method, then DOX was loaded into the mesoporous channels of MSN, and locked by the PDA coating. Next, ICG was modified by π-π stacking on PDA, and finally, MnO2layer was accumulated on the surface of DOX@MSN@PDA- ICG@MnO2, achieving orthogonal loading and sequential release of different drugs. DMPIM first generated oxygen (O2) through the reaction between MnO2and H2O2after entering tumor cells, alleviating the hypoxic environment of tumors and enhancing the PDT effect of sequentially released ICG. Afterwards, ICG reacted with O2in tumor tissue to produce reactive oxygen species, promoting lysosomal escape of drugs and inactivation of p-glycoprotein (p-gp) on tumor cell membranes. DOX loaded in the MSN channels exhibited a delay of approximately 8 h after ICG release to exert the enhanced chemotherapy effect. The drug delivery system achieved effective sequential release and multimodal combination therapy, which achieved ideal therapeutic effects on malignant tumors. This work offers a route to a sequential drug release for advancing the treatment of malignant tumors.

Pillararene-Based Stimuli-Responsive Supramolecular Delivery Systems for Cancer Therapy

Cancer poses a significant challenge to global public health, seriously threatening human health and life. Although various therapeutic strategies, such as chemotherapy (CT), radiotherapy, phototherapy, and starvation therapy, are applied to cancer treatment, their limited therapeutic effect, severe side effects, and unsatisfactory drug release behavior need to be carefully considered. Thus, there is an urgent need to develop efficient drug delivery strategies for improving cancer treatment efficacy and realizing on-demand drug delivery. Notably, pillararenes, as an emerging class of supramolecular macrocycles, possess unique properties of highly tunable structures, superior host-guest chemistry, facile modification, and good biocompatibility, which are widely used in cancer therapy to achieve controllable drug release and reduce the toxic side effects on normal tissues under various internal/external stimuli conditions. This review summarizes the recent advance of stimuli-responsive supramolecular delivery systems (SDSs) based on pillararenes for tumor therapy from the perspectives of different assembly methods and hybrid materials, including molecular-scale SDSs, supramolecular nano self-assembly delivery systems, and nanohybrid SDSs. Moreover, the prospects and critical challenges of stimuli-responsive SDSs based on pillararenes for cancer therapy are also discussed.

Platelet-mimicking supramolecular nanomedicine with precisely integrated prodrugs for cascade amplification of synergistic chemotherapy

Camptothecin (CPT) and cisplatin (Pt) have shown synergistic effects on a variety of cancers during preclinical and clinical studies. However, the ratio of the two drugs often could not be precisely regulated in different delivery systems, which hinders the desired synergistic effect. In addition, the low delivery efficiency of the two drugs to the tumor further impedes the ideal therapeutic outcomes. Herein, we report that a platelet-mimicking supramolecular nanomedicine (SN) could precisely control of the ratio of CPT and Pt with a high tumor accumulation rate for cascade amplification of synergistic chemotherapy. The SN was fabricated via the host-guest interaction between cucurbit[7]uril conjugated hyaluronic acid (HA-CB[7]) and adamantane (ADA) respectively functionalized CPT- and Pt-based prodrugs. The ratio of CPT and Pt in the SN could be facilely regulated by simply controlling the loading ratio, based on the strong binding affinity between CB[7] and ADA, and SN60 with 60% CPT and 40% Pt showed the highest synergistic effects on 4T1 cells. To improve the tumor accumulation efficiency of SN, 5,6-dimethylxanthenone-4-acetic acid (DMXAA, a tumor vasculature-disruptive agent) was loaded into the optimized SN and then coated with platelet membrane to yield platelet-mimicking supramolecular nanomedicine (D@SN-P). D@SN-P could first passively accumulate in tumors owing to the enhanced permeability and retention (EPR) effect after intravenous administration. The initially release of DMXAA from D@SN-P could induce tumor vascular disruption, and the resultant epithelial collagen exposure around the disrupted tumor vasculature provided a target for further recruitment of platelet-mimicking SN, leading to cascade amplification of tumor accumulation with synergistic chemotherapy. Hence, this platelet-mimicking supramolecular nanomedicine presents a universal supramolecular strategy to finely regulate the ratio of loaded pro-drugs, and improve the accumulation efficiency to amplify chemotherapy via platelet-mimics.

A cyclic brush zwitterionic polymer based pH-responsive nanocarrier-mediated dual drug delivery system with lubrication maintenance for osteoarthritis treatment

Enhanced joint synergistic lubrication combined with anti-inflammatory therapy is an effective strategy to delay the progression of early osteoarthritis (OA) but has been rarely reported. The hydration lubrication of zwitterions and inherent super-lubrication properties of the cyclic brush, as well as the enhancement of the steric stability of the cyclic topology, can effectively improve the drug loading and utilization; herein we report a pH-responsive cyclic brush zwitterionic polymer (CB) with SBMA and DMAEMA as brushes and a cyclic polymer (c-P(HEMA)) as the core template, possessing a low coefficient of friction (0.017). After loading with hydrophobic curcumin and hydrophilic loxoprofen sodium it demonstrates high drug-loading efficiency. In vitro and in vivo experiments confirmed the triple function of the CB on superlubrication, sequence controlled release and anti-inflammatory effects demonstrated by Micro CT, histological analysis and qRT-PCR. Overall, the CB is a promising long-acting lubricating therapeutic agent, with potential for OA treatment or other diseases.

Fluorinated carboxymethyl chitosan-based nano-prodrugs for precisely synergistic chemotherapy

The clinical transformation of polysaccharide-based nano-prodrugs remains a long way off, due to the shackles on easy metabolic clearance, dilemma of dose-dependent toxicity and immunogenicity, and poor tumor selectivity. To address these challenges, the fluorinated dual-crosslinked carboxymethyl chitosan (CMCS)-based nano-prodrugs with precise structure were facilely developed through the reaction of CMCS with water-soluble stimuli-responsive synergistic small molecule prodrug (Pt(IV)-1), glutaraldehyde and heptafluorobutyric anhydride successively. The fluorination enabled the nano-prodrugs to display metabolic stability and improve tumoral cellular uptake. The pH/glutathione (GSH)-sensitive dual-crosslinked structure enabled the nano-prodrugs to show physicochemical stability at physiological pH, selective drug release and synergistic cytotoxicity at tumoral intracellular pH/GSH, and circumventing the dilemma of dose-dependent toxicity and immunogenicity induced by that crosslinked or grafted via a single drug. These superior performances promoted stability in long-term storage and circulation, normal blood routine and aminotransferase, fantastic hemocompatibility, selective tumor accumulation and precisely synergistic chemotherapy, therefore achieving significant tumor growth inhibition while minimizing side effects. Thus, the precise fluorinated dual-crosslinked CMCS-based nano-prodrugs have great potential for selective clinical cancer treatment.

Drug Self-Delivery Systems: Molecule Design, Construction Strategy, and Biological Application

Drug self-delivery systems (DSDSs) offer new ways to create novel drug delivery systems (DDSs). In typical DSDSs, therapeutic reagents are not considered passive cargos but active delivery agents of actionable targets. As an advanced drug delivery strategy, DSDSs with positive cooperativity of both free drugs and nanocarriers exhibit the clear merits of unprecedented drug-loading capacity, minimized systemic toxicity, and flexible preparation of nanoscale deliverables for passive targeted therapy. This review highlights the recent advances and future trends in DSDSs on the basis of two differently constructed structures: covalent and noncovalent bond-based DSDSs. Specifically, various chemical and architectural designs, fabrication strategies, and responsive and functional features are comprehensively discussed for these two types of DSDSs. In addition, additional comments on the current development status of DSDSs and the potential applications of their molecular designs are presented in the corresponding discussion. Finally, the promising potential of DSDSs in biological applications is revealed and the relationship between preliminary molecular design of DSDSs and therapeutic effects of subsequent DSDSs biological applications is clarified.

Dynamic crosslinked polymeric nano-prodrugs for highly selective synergistic chemotherapy

To achieve highly selective synergistic chemotherapy attractive for clinical translation, the precise polymeric nano-prodrugs (PPD-NPs) were successfully constructed via the facile crosslinking reaction between pH-sensitive poly(ortho ester)s and reduction-sensitive small molecule synergistic prodrug (Pt(IV)-1). PPD-NPs endowed the defined structure and high drug loading of cisplatin and demethylcantharidin (DMC). Moreover, PPD-NPs exhibited steady long-term storage and circulation via the crosslinked structure, suitable negative potentials and low critical micelle concentration (CMC), improved selective tumour accumulation and cellular internalization via dynamic size transition and surficial amino protonation at tumoural extracellular pH, promoted efficient disintegration and drug release at tumoural intracellular pH/glutathione, and enhanced cytotoxicity via the synergistic effect between cisplatin and DMC with the feed ratio of 1:2, achieving significant tumour suppression while decreasing the side effects. Thus, the dynamic crosslinked polymeric nano-prodrugs exhibit tremendous potential for clinically targeted synergistic cancer therapy.

Supramolecular self-assemblies based on water-soluble pillar[6]arene and drug-drug conjugates for the combination of chemotherapy

Although some co-drug delivery systems have been reported to treat cancer, how to optimal design these nano-systems with enhanced therapeutic efficacy is still a major challenge. As for the nitrogen mustard drugs chlorambucil (Cb), the overexpressed glutathione (GSH) in cancer tissue is responsible for their detoxification and reduced bioavailability. In this paper, chlorambucil-oxoplatin (Cb-Pt) was prepared to fabricate water-soluble pillar[6]arene (WP[6]) based supramolecular drug-drug self-assemblies (SDSAs). Remarkably, after the transcytosis by cancer cells, SDSAs was reduced by GSH to re lease Cb and higher toxic cisplatin, accompanying with the declining GSH level and ascending ROS level. Moreover, in vitro and in vivo experiments demonstrated that SDSAs with oxidative stress amplification strategy exhibited excellent therapeutic effect. This strategy might be useful for the synergistic co-drug based chemotherapy field.

Iron ion-coordinated carrier-free supramolecular co-nanoassemblies of dual DNA topoisomerase-targeting inhibitors for tumor suppression

Overexpressed DNA topoisomerase II alpha (TOP-2A) is closely related to the invasion and metastasis of malignant breast tumors. Mitoxantrone (MTX) has been identified as a TOP-2A inhibitor with significant inhibitory activity against breast tumors. The tumor-homing ability of MTX has been further enhanced by using nanodrug delivery systems (nano-DDSs), reducing off-target side effects. However, conventional MTX nano-DDSs are still limited by low drug-loading capacity and material carrier-related toxicity. In this study, we developed metal iron-coordinated carrier-free supramolecular co-nanoassemblies of dual DNA topoisomerase-targeting inhibitors with high drug loading for superimposed DNA damage-augmented tumor regression. By introducing iron ions (Ⅲ) and another TOP-2A inhibitor quercetin (QU) onto the building blocks, Fe³⁺-mediated QU-MTX co-nanoassemblies are fabricated (QU-MTX-Fe) via intermolecular coordination interactions. The PEGylated co-nanoassemblies (P-QU-MTX-Fe) exhibit distinct advantages over QU/MTX solution (Sol) alone or MTX-QU mixture Sol in terms of therapeutic efficacy and systemic toxicity. Meanwhile, P-QU-MTX-Fe could efficiently suppress primary and distal breast tumor relapse by activating the CD 8⁺-mediated antitumor immune response. Overall, such iron-coordinated nanomedicines provide insights into the rational design of drug-likeness compounds with undesirable therapeutic performance for cancer therapy. STATEMENT OF SIGNIFICANCE: Aimed at the key target TOP-2A in the malignant breast tumor, the metal coordination-mediated supramolecular co-assemble strategy of one-target dual inhibitors was firstly proposed for superimposed DNA damage for cancer therapy. Multiple interactions involving π-π stacking interactions, hydrogen bonds and coordination forces maintained the stability of co-nanoassemblies. Meanwhile, this co-nanoassemblies not only had potentials to increase therapeutic efficacy and decrease systemic toxicity, but also activated the CD 8⁺-mediated antitumor immune response against distal breast tumor relapse. Such a facile and safe nanoplatform is expected to provide an important prospective for promoting the clinical transformation of drug-likeness compounds in the suppression of difficult-to-treat breast tumor.

Metal-coordinated nanomedicine for combined tumor therapy by inducing paraptosis and apoptosis

Apoptosis resistance of tumor cells often results in chemoresistance and treatment failure in clinic. In this work, a Cu²⁺-coordinated morusin/doxorubicin biological organizer (designated as COMBO) is designed to combat cellular resistance to apoptosis for combined tumor therapy. By virtue of the coordination and π-π stacking effects, the self-assembled COMBO possesses nanometer particle size, narrow and homogenous graininess distribution as well as a good dispersion stability. Moreover, COMBO could be disassembled by glutathione (GSH) with an effective drug release and fluorescence recovery. Morusin-mediated paraptosis could induce extensive vacuolization through the dilation of endoplasmic reticulum (ER) and mitochondria, leading to non-apoptotic programmed cell death (PCD) regardless of the cellular resistance to apoptosis. Furthermore, the released doxorubicin prefers to locate in cell nucleus to cause cell apoptosis for combined chemotherapy. By the joint action of paraptosis and apoptosis, COMBO exhibits a great superiority over monotherapy in tumor inhibition with a low system toxicity. This study may open a window in the development of self-delivery nanomedicine for overcoming apoptosis resistance in tumor therapy.

Platinum-Containing Supramolecular Drug Self-Delivery Nanomicelles for Efficient Synergistic Combination Chemotherapy

Supramolecular drug self-delivery systems (SDSDSs) involving active drugs as building blocks linked by supramolecular interactions have been well defined as an advanced chemotherapy strategy. However, the lack of detecting release of drugs from SDSDSs at specific tumor sites inevitably leads to unsatisfactory therapeutic effects, owing to the lack of information regarding the administration of these drugs. In this work, predesigned platinum-containing supramolecular drug self-delivery nanomicelles (SDSDNMs) were employed to synchronously realize drug monitoring by computed tomography imaging, immediately reflecting the evolution of drug release and real-time treatment at the tumor site. The appropriate administration dosage (1.2 mg mL^-1,100 μL) and the injection interval (once every 3 days) needed to guide the antitumor activity of SDSDNMs were then defined, thereby attaining the aim of efficient synergistic combination chemotherapy. In vivo tumor inhibition and histological analyses showed that SDSDNMs exhibited a strong tumor inhibition effect and good safety with respect to normal organs. Such a supramolecular drug self-delivery strategy with monitored functions may offer new potential opportunities for application in the field of synergistic combination chemotherapy.

Near-Infrared Photo-controlled Permeability of a Biomimetic Polymersome with Sustained Drug Release and Efficient Tumor Therapy

Synthetic polymersomes have structure similarity to bio-vesicles and could disassemble in response to stimuli for "on-demand" release of encapsulated cargos. Though widely applied as a drug delivery carrier, the burst release mode with structure complete destruction is usually taken for most responsive polymersomes, which would shorten the effective drug reaction time and impair the therapeutic effect. Inspired by the cell organelles' communication mode via regulating membrane permeability for transportation control, we highlight here a biomimetic polymersome with sustained drug release over a specific period of time via near-infrared (NIR) pre-activation. The polymersome is prepared by the self-assembling amphiphilic diblock copolymer P(OEGMA-co-EoS)-b-PNBOC and encapsulates the hypoxia-activated prodrug AQ4N and upconversion nanoparticle (PEG-UCNP) in its hydrophilic centric cavity. Thirty minutes of NIR pre-activation triggers cross-linking of NBOC and converts the permeability of the polymersome with sustained AQ4N release until 24 h after the NIR pre-activation. The photosensitizer EoS is activated and aggravates environmental hypoxic conditions during a sustained drug release period to boost the AQ4N therapeutic effect. The combination of sustained drug release with concurrent hypoxia intensification results in a highly efficient tumor therapeutic effect both intracellularly and in vivo. This biomimetic polymersome will provide an effective and universal tumor therapeutic approach.

Sequential administration of sialic acid-modified liposomes as carriers for epirubicin and zoledronate elicit stronger antitumor effects with reduced toxicity

Combined administration of drugs can improve efficacy and reduce toxicity; therefore, this combination approach has become a routine method in cancer therapy. The main combination regimens are sequential, mixed (also termed "cocktail"), and co-loaded; however, other combinations, such as administration of synergistic drugs and the use of formulations with different mechanisms of action, may exert better therapeutic effects. Tumor-associated macrophages (TAMs) play functional roles throughout tumor progression and exhibit characteristic phenotypic plasticity. Sialic acid (SA)-modified epirubicin liposomes (S-E-L) and SA-modified zoledronate liposomes (S-Z-L) administered separately kill TAMs, reverse their phenotype, and achieve antitumor effects. In this study, we examined the effects of a two-treatment combination for drug delivery, using sequential, mixed, and co-loaded drug delivery. We found that therapeutic effects differed between administration methods: mixed administration of S-E-L and S-Z-L, co-loaded administration of SA-modified liposomes (S-ZE-C), and sequential administration of S-E-L injected 24 h after S-Z-L did not inhibit tumor growth; however, sequential administration of S-Z-L injected 24 h after S-E-L resulted in no tumor growth, no toxicity to noncancerous tissue, and no death of mice, and exhibited 25% tumor shedding. Thus, our results thus encourage the further development of combined therapies for nanomedicines based on the mechanisms investigated here.

Efficient FRET Approaches toward Copper(II) and Cyanide Detections via Host-Guest Interactions of Photo-Switchable [2]Pseudo-Rotaxane Polymers Containing Naphthalimide and Merocyanine Moieties

A supramolecular [2]pseudo-rotaxane containing a naphthalimide-based pillararene host and a spiropyran-based imidazole guest was synthesized and investigated in a semiaqueous solution with 90% water fraction. Upon UV exposure, the close-form structure of nonemissive spiropyran guest could be transformed into the open-form structure of red-emissive merocyanine guest reversibly, which was utilized as a monofluorophoric sensor to detect copper(II) and cyanide ions. Moreover, the naphthalimide host as an energy donor with green photoluminescence (PL) emission at 505 nm was complexed with the merocyanine guest as an energy acceptor with red PL emission at 650 nm in 1:1 molar ratio to generate a [2]pseudo-rotaxane polymer, which was further verified by the diffusion coefficients of DOSY nuclear magnetic resonance (NMR) measurements. Due to the Förster resonance energy transfer (FRET) processes, the bifluorophoric [2]pseudo-rotaxane produced more efficient ratiometric PL behavior to induce a stronger red PL emission than that of the monofluorophoric guest; therefore, the PL sensor responses of the supramolecular [2]pseudo-rotaxane toward copper(II) and cyanide ions could be further amplified via the FRET-OFF processes to turn off red PL emission of the reacted merocyanine acceptor and to recover green PL emission of the naphthalimide donor. Accordingly, the best and prominent values of the limit of detection (LOD) for the host-guest detections toward Cu²⁺ and CN^- were 0.53 and 1.34 μM, respectively. The highest red MC emission with the optimum FRET processes of [2]pseudo-rotaxane was maintained around room temperature (20-40 °C) in wide pH conditions (pH = 3-13), which can be utilized in the cell viability tests to prove the nontoxic and remarkable biomarker of [2]pseudo-rotaxane to detect Cu²⁺ and CN^- in living cells. The developed FRET-OFF processes with ratiometric PL behavior of the bifluorophoric supramolecular [2]pseudo-rotaxane polymer will open a new avenue to the future applications of chemo- and biosensors.

A dual drug-based hyperbranched polymer with methotrexate and chlorambucil moieties for synergistic cancer chemotherapy

Dual drug-based hyperbranched polymer micelles simultaneously containing methotrexate and chlorambucil were constructed for synergistic cancer chemotherapy.