Camptothecin-Polysaccharide Co-assembly and Its Controlled Release

20-esterification of 5-spiro CPT and their anticancer activity in vitro

20-ester of 5-spirocycle campthothecin derivatives were successfully constructed and synthesised by Steglich esterification in a moderate yield. These derivatives showed a better solubility. Compared to parent compound, most of these 20-ester-5-spirocycle campthothecin derivatives (besides 3g) showed a better inhibition activity against HepG2 cell line.

Cyclodextrin-Based Polymeric Drug Delivery Systems for Cancer Therapy

Cyclodextrins (CDs) are one of the most extensively studied cyclic-oligosaccharides due to their low toxicity, good biodegradability and biocompatibility, facile chemical modification, and unique inclusion capacity. However, problems such as poor pharmacokinetics, plasma membrane disruption, hemolytic effects and a lack of target specificity still exist for their applications as drug carriers. Recently, polymers have been introduced into CDs to combine the advantages of both biomaterials for the superior delivery of anticancer agents in cancer treatment. In this review, we summarize four types of CD-based polymeric carriers for the delivery of chemotherapeutics or gene agents for cancer therapy. These CD-based polymers were classified based on their structural properties. Most of the CD-based polymers were amphiphilic with the introduction of hydrophobic/hydrophilic segments and were able to form nanoassemblies. Anticancer drugs could be included in the cavity of CDs, encapsulated in the nanoparticles or conjugated on the CD-based polymers. In addition, the unique structures of CDs enable the functionalization of targeting agents and stimuli-responsive materials to realize the targeting and precise release of anticancer agents. In summary, CD-based polymers are attractive carriers for anticancer agents.

Hyaluronic Acid within Self-Assembling Nanoparticles: Endless Possibilities for Targeted Cancer Therapy

Self-assembling nanoparticles (SANPs) based on hyaluronic acid (HA) represent unique tools in cancer therapy because they combine the HA targeting activity towards cancer cells with the advantageous features of the self-assembling nanosystems, i.e., chemical versatility and ease of preparation and scalability. This review describes the key outcomes arising from the combination of HA and SANPs, focusing on nanomaterials where HA and/or HA-derivatives are inserted within the self-assembling nanostructure. We elucidate the different HA derivatization strategies proposed for this scope, as well as the preparation methods used for the fabrication of the delivery device. After showing the biological results in the employed in vivo and in vitro models, we discussed the pros and cons of each nanosystem, opening a discussion on which approach represents the most promising strategy for further investigation and effective therapeutic protocol development.

Supramolecular biomaterials for bio-imaging and imaging-guided therapy

Benefiting from their unique advantages, including reversibly switchable structures, good biocompatibility, facile functionalization, and sensitive response to biological stimuli, supramolecular biomaterials have been widely applied in biomedicine. In this review, the representative achievements and trends in the design of supramolecular biomaterials (mainly those derived from biomacromolecules) with specific macromolecules including peptides, deoxyribonucleic acid, and polysaccharides, as well as their applications in bio-imaging and imaging-guided therapy are summarized. This review will serve as an important summary and "go for" reference for explorations of the applications of supramolecular biomaterials in bio-imaging and image-guided therapy, and will promote the development of supramolecular chemistry as an emerging interdisciplinary research area.

Design and evaluation of glutathione responsive glycosylated camptothecin nanosupramolecular prodrug

A novel tumor-targeted glutathione responsive Glycosylated-Camptothecin nanosupramolecular prodrug (CPT-GL NSp) was designed and fabricated via a disulfide bond. The effects of glycoligand with different polarities on solubility, self-assembly, stability, cellular uptake, and glutathione responsive cleaving were explored, and an optimal glycosylated ligand was selected for nanosupramolecular prodrug. It has been found that CPT-GL NSp exhibited higher drug loading than traditional nanoparticles. Among of which maltose modified NSp had the strongest anti-tumor effects than that of glucose and maltotriose. CPT-SS-Maltose had a similar anti-tumor ability to Irinotecan (IR), but the superior performance in solubility, hemolysis, and uptake of HepG2 cells.

Chemosensitization of Temozolomide-Resistant Pediatric Diffuse Midline Glioma Using Potent Nanoencapsulated Forms of a N(3)-Propargyl Analogue

The lack of clinical response to the alkylating agent temozolomide (TMZ) in pediatric diffuse midline/intrinsic pontine glioma (DIPG) has been associated with O6-methylguanine-DNA-methyltransferase (MGMT) expression and mismatch repair deficiency. Hence, a potent N(3)-propargyl analogue (N3P) was derived, which not only evades MGMT but also remains effective in mismatch repair deficient cells. Due to the poor pharmacokinetic profile of N3P (t1/2 < 1 h) and to bypass the blood-brain barrier, we proposed convection enhanced delivery (CED) as a method of administration to decrease dose and systemic toxicity. Moreover, to enhance N3P solubility, stability, and sustained distribution in vivo, either it was incorporated into an apoferritin (AFt) nanocage or its sulfobutyl ether β-cyclodextrin complex was loaded into nanoliposomes (Lip). The resultant AFt-N3P and Lip-N3P nanoparticles (NPs) had hydrodynamic diameters of 14 vs 93 nm, icosahedral vs spherical morphology, negative surface charge (-17 vs -34 mV), and encapsulating ∼630 vs ∼21000 N3P molecules per NP, respectively. Both NPs showed a sustained release profile and instant uptake within 1 h incubation in vitro. In comparison to the naked drug, N3P NPs demonstrated stronger anticancer efficacy against 2D TMZ-resistant DIPG cell cultures [IC50 = 14.6 (Lip-N3P) vs 32.8 μM (N3P); DIPG-IV) and (IC50 = 101.8 (AFt-N3P) vs 111.9 μM (N3P); DIPG-VI)]. Likewise, both N3P-NPs significantly (P < 0.01) inhibited 3D spheroid growth compared to the native N3P in MGMT+ DIPG-VI (100 μM) and mismatch repair deficient DIPG-XIX (50 μM) cultures. Interestingly, the potency of TMZ was remarkably enhanced when encapsulated in AFt NPs against DIPG-IV, -VI, and -XIX spheroid cultures. Dynamic PET scans of CED-administered zirconium-89 (89Zr)-labeled AFt-NPs in rats also demonstrated substantial enhancement over free 89Zr radionuclide in terms of localized distribution kinetics and retention within the brain parenchyma. Overall, both NP formulations of N3P represent promising approaches for treatment of TMZ-resistant DIPG and merit the next phase of preclinical evaluation.

Construction of Hyaluronic Acid-Covered Hierarchically Porous MIL-nanoMOF for Loading and Controlled Release of Doxorubicin

The porous nano-sized metal-organic framework (nanoMOF) and its proper surface modification could greatly promote the drug loading capability and introduce biocompatibility, biodegradability, and targeting functions into nano-drug delivery systems. Herein, the HACD@ADA-PA/MIL-101_NH₂ (Fe)-P nanoparticle was successfully fabricated through supramolecular and coordination interactions from three building blocks, including hierarchically porous MIL-101_NH₂ (Fe)-P nanoMOF, phosphite-modified adamantane (ADA-PA), and β-cyclodextrin (β-CD)-modified hyaluronic acid (HACD). The obtained HACD@ADA-PA/MIL-101_NH₂ (Fe)-P nanoparticle was nano-sized and highly stable in physiological fluids. The porous structure of HACD@ADA-PA/MIL-101_NH₂ (Fe)-P nanoparticle could effectively load the commercial chemotherapeutic drug doxorubicin (DOX) with an encapsulation rate of 41.20 % and a loading rate of 48.84 %. The obtained drug-loaded HACD@ADA-PA/MIL-101_NH₂ (Fe)-P@DOX nanoparticle was pH-sensitive and relatively stable at neutral condition (pH 7.2) but could release DOX in a controlled way in subacid solution at pH 5.7. The simulated in vitro DOX release experiment signified that the HACD@ADA-PA/MIL-101_NH₂ (Fe)-P@DOX nanoparticle could realize the controlled release of DOX in tumor issues.

Purely organic light-harvesting phosphorescence energy transfer by β-cyclodextrin pseudorotaxane for mitochondria targeted imaging

A new type of purely organic light-harvesting phosphorescence energy transfer (PET) supramolecular assembly is constructed from 4-(4-bromophenyl)-pyridine modified β-cyclodextrin (CD-PY) as a donor, cucurbit[8]uril (CB[8]) as a mediator, rhodamine B (RhB) as an acceptor, and adamantane modified hyaluronic acid (HA-ADA) as a cancer cell targeting agent. Interestingly, the complexation of free CD-PY, which has no RTP emission in aqueous solution, with CB[8] results in the formation of CD-PY@CB[8] pseudorotaxane with an RTP emission at 510 nm. Then the addition of RhB leads to an efficient light-harvesting PET process with highly efficient energy transfer and an ultrahigh antenna effect (36.42) between CD-PY@CB[8] pseudorotaxane and RhB. Importantly, CD-PY@CB[8]@RhB assembles with HA-ADA into nanoparticles with further enhanced delayed emission at 590 nm. The nanoparticles could be successfully used for mitochondria targeted imaging in A549 cancer cells. This aqueous-state PET based on a supramolecular assembly strategy has potential application in delayed fluorescence cell imaging.

A new type of purely organic light-harvesting PET supramolecular assembly is constructed with efficient energy transfer and ultrahigh antenna effect. Moreover, the assembly could be used for mitochondria targeted imaging in A549 cancer cells.

Cyclodextrin as a magic switch in covalent and non-covalent anticancer drug release systems

Cancer has been a threat to human health, so its treatment is a huge challenge to the present medical field. One of commonly used methods is the controlled release of anticancer drug to reduce the dose for patients, increase the stability of drug treatment and minimize side effects. Cyclodextrin is a kind of cyclic oligosaccharide produced by amylase hydrolysis. Because cyclodextrin contains a cavity structure and active hydroxyl groups, it has a positive effect on the study of the controlled release of anticancer drugs. This article reviews the controlled release of current anticancer drugs based on cyclodextrins as a "flexible switch", and discusses the classification of different types of release systems, highlighting their role in cancer treatment. Moreover, the opportunities and challenges of cyclodextrin as a magic switch in the controlled release of anticancer drugs are discussed.

Antitumour properties based on the self-assembly of camptothecin and carbamoylmannose conjugates

Camptothecin (CPT) and its analogues show potent antitumour activity. However, poor water solubility and severe side effects have restricted their applications in clinical practice. In this paper, a novel self-assembly based on camptothecin and carbamoylmannose conjugates (CPT-Man) was constructed. The self-assembly increased the water solubility of camptothecin to 0.64 mg/ml and antitumour activity. Moreover, CPT-Man could induce obvious cancer cell apoptosis. This work provides a new approach for exploring carbohydrate-modified antitumour properties by self-assembled CPT drugs.

Enzyme-responsive fluorescent camptothecin prodrug/polysaccharide supramolecular assembly for targeted cellular imaging and in situ controlled drug release

An enzyme-responsive polysaccharide assembly was constructed, which possesses low cytotoxicity, targeted imaging and controlled drug release, while providing a concurrent means for the real-time tracking of drug delivery.

Injectable, Biodegradable, Thermosensitive Nanoparticles-Aggregated Hydrogel with Tumor-Specific Targeting, Penetration, and Release for Efficient Postsurgical Prevention of Tumor Recurrence

High locoregional recurrence of breast cancer after surgery remains a clinically appealing challenge. Local chemotherapy, especially sustainable delivery of chemotherapeutics at tumor sites by implantable hydrogels, has shown great potential to prevent cancer recurrence. However, the applications of conventional hydrogels are often limited by their intrinsic poor drug penetration into solid tumors and nonspecific drug accumulation in adjacent normal tissues. Herein, we developed a novel modular coassembly strategy to prepare a kind of pH-sensitive, tumor-specific targeting, and penetrating peptide (CRGDK)-modified doxorubicin-based prodrug nanoparticles (PDNPs), whose aqueous dispersion can undergo sol-gel transition after in vivo injection by thermo-induced self-aggregation to in situ form biodegradable hydrogel depot (PDNPs-gel), anchoring high amounts of PDNPs at tumor sites. Because of CRGDK-mediated targeting to overexpressed neuropilin-1 receptors on tumor vessels and tumor cells, PDNPs released from PDNPs-gel can effectively penetrate into tumor tissues, specifically enter tumor cells and finally realize intracellular acid-triggered drug release. In an in vivo incomplete resection of breast cancer model, a single peritumoral administration of PDNP-gel can achieve high inhibition efficacy against tumor recurrence. In addition, the administration of PDNP-gel only involves simple redispersion of PDNPs in water without any pretreatment for gelation, providing great convenience for storage, dosage, and prescription in practical use. Collectively, the reported multifunctional nanoparticles self-aggregated hydrogel system possesses great potential for efficient postsurgical prevention of tumor recurrence.

A supramolecular hydrophobic guest transport system based on a biological macrocycle

A protein-based macrocyclic bioactive guest loading system has been developed, which not only provides a stable 10 nm scale lipophilic environment, but also increases the solubility of potent anticancer agent SN38 in its active lactone form in aqueous medium.

A highly biocompatible biogenic macrocycle was utilized to enhance the water-solubility and pH stability of the potent antineoplastic agent SN38.

GSH-Responsive supramolecular nanoparticles constructed by β-d-galactose-modified pillar[5]arene and camptothecin prodrug for targeted anticancer drug delivery

Supramolecular construction of a targeted and stimuli-responsive drug delivery system is still a challenging task. Herein, GSH-responsive supramolecular prodrug nanoparticles were constructed by the host-guest complexation between a β-d-galactose-functionalized water-soluble pillar[5]arene (GalP5) and a disulfide bond containing camptothecin prodrug (G). The obtained prodrug nanoparticles were stable under physiological conditions, whereas efficient drug release was triggered in a simulated tumor environment with high GSH concentration. In vitro studies revealed that these prodrug nanoparticles preferentially entered asialoglycoprotein receptor-overexpressing HepG2 cells due to the active targeting effect of galactose units. This active targeting effect resulted in the maximization of anticancer efficacy and reduction of the undesirable side effects to normal cells.

Cyclodextrin-based biological stimuli-responsive carriers for smart and precision medicine

Spurred on by recent progress in nanotechnology and precision medicine, smart drug carriers are entering an entirely new era. Smart drug carriers have been widely studied in recent years as a result of their ability to control drug release under different microenvironments (such as pH, redox, and enzyme) in vivo. Host-guest interactions based on cyclodextrins have proven to be an efficient tool for fabricating smart drug carriers. Because of the application of host-guest interactions, many kinds of biological molecules or supramolecular building blocks can combine into an organic whole at the molecular level. In this review, the features, mechanisms of action, and potent applications of biological stimuli-responsive drug carriers based on cyclodextrins are discussed. In addition, some personal perspectives on this field are presented.

A Modular Coassembly Approach to All-In-One Multifunctional Nanoplatform for Synergistic Codelivery of Doxorubicin and Curcumin

Synergistic combination therapy by integrating chemotherapeutics and chemosensitizers into nanoparticles has demonstrated great potential to reduce side effects, overcome multidrug resistance (MDR), and thus improve therapeutic efficacy. However, with regard to the nanocarriers for multidrug codelivery, it remains a strong challenge to maintain design simplicity, while incorporating the desirable multifunctionalities, such as coloaded high payloads, targeted delivery, hemodynamic stability, and also to ensure low drug leakage before reaching the tumor site, but simultaneously the corelease of drugs in the same cancer cell. Herein, we developed a facile modular coassembly approach to construct an all-in-one multifunctional multidrug delivery system for the synergistic codelivery of doxorubicin (DOX, chemotherapeutic agent) and curcumin (CUR, MDR modulator). The acid-cleavable PEGylated polymeric prodrug (DOX-h-PCEC), tumor cell-specific targeting peptide (CRGDK-PEG-PCL), and natural chemosensitizer (CUR) were ratiometrically assembled into in one single nanocarrier (CUR/DOX-h-PCEC@CRGDK NPs). The resulting CUR/DOX-h-PCEC@CRGDK NPs exhibited several desirable characteristics, such as efficient and ratiometric drug loading, high hemodynamic stability and low drug leakage, tumor intracellular acid-triggered cleavage, and subsequent intracellular simultaneous drug corelease, which are expected to maximize a synergistic effect of chemotherapy and chemosensitization. Collectively, the multifunctional nanocarrier is feasible for the creation of a robust nanoplatform for targeted multidrug codelivery and efficient MDR modulation.

The supramolecular polymer complexes with oppositely charged calixresorcinarene: hydrophobic domain formation and synergistic binding modes

The association of branched polyethyleneimine (PEI) with a series of octacarboxy-calixresorcinarenes bearing different low-rim substituents leads to the formation of nanosized supramolecular complexes. The PEI-macrocycle complexes have fine-tunable sizes regulated by variations in the self-association capacity of the calixresorcinarenes. In the supramolecular complexes, hydrophobic fragments of the polymer and calixresorcinarenes form cooperative hydrophobic domains which provide synergistic enhancement of guest molecule binding. The formation of the supramolecular complexes was investigated by NMR FT-PGSE, NMR 2D NOESY, DLS and TEM methods. In addition, fluorimetry and UV-vis methods were used with the help of optical probes, namely water-soluble Crystal Violet and water-insoluble Orange OT. The investigation demonstrates the first example of the formation of cooperative hydrophobic domains in supramolecular polyelectrolyte-macrocycle complexes which enhance the binding of both water-soluble and water-insoluble organic compounds. The presented supramolecular systems have potential as sensory and drug delivery systems.

Dual targeting system by supramolecular complex of folate-conjugated methyl-β-cyclodextrin with adamantane-grafted hyaluronic acid for the treatment of colorectal cancer

In our previous study, we demonstrated that folate-appended methyl‑β‑cyclodextrin (FA-M-β-CyD) was a promising antitumor agent for the treatment of folate receptor-α (FR-α)-expressing tumors. In the present study, to enhance the antitumor effect of FA-M-β-CyD against FR-α- and CD44-expressing colorectal cancer cells, we synthesized a dual targeting supramolecular complex composed of FA-M-β-CyD and adamantane-grafted hyaluronic acid (Ad-HA). The supramolecular complex of Ad-HA/FA-M-β-CyD showed higher cytotoxic activity in HCT116 cells (FR-α (+), CD44 (+)), a human colon cancer cell line, than FA-M-β-CyD alone. In addition, the cytotoxic activity of Ad-HA/FA-M-β-CyD was significantly impaired by the addition of FA and HA, as inhibitors of FR-α and CD44, respectively. Furthermore, tetramethylrhodamine isothiocyanate (TRITC)-labeled FA-M-β-CyD was efficiently internalized into HCT116 cells through supramolecular complexation with Ad-HA, compared to that of TRITC-FA-M-β-CyD alone. Additionally, Ad-HA/FA-M-β-CyD induced mitophagy in HCT116 cells. These results suggest that Ad-HA/FA-M-β-CyD targeted HCT116 cells, as well as induced mitophagy-mediated cell death. Notably, an intravenous injection of the Ad-HA/FA-M-β-CyD complex in a mouse model of colorectal cancer significantly ameliorated the growth of tumor polyps. Collectively, these results suggest that Ad-HA/FA-M-β-CyD has antiproliferation effects in tumors, based on the dual targeting activity.

Supramolecular Complex of Methyl-β-cyclodextrin with Adamantane-Grafted Hyaluronic Acid as a Novel Antitumor Agent

Methyl-β-cyclodextrin (M-β-CyD) exhibits cytotoxic activity, and has the potentials as an antitumor agent. However, a tumor-selectivity of M-β-CyD is low, leading to low antitumor activity and the adverse effects. Meanwhile, hyaluronic acid (HA) is known as a promising tumor targeting ligand, because various cancer cells overexpress CD44, a HA-binding glycoprotein. In the present study, to develop a tumor-selective delivery system for M-β-CyD, we designed a supramolecular complex of M-β-CyD with adamantane-grafted HA (Ad-HA/M-β-CyD) and evaluated it as a tumor-selective antitumor agent. M-β-CyD formed a stable complex with Ad-HA (K_c>10⁴ M^-1). In addition, Ad-HA/M-β-CyD formed slightly a negative-charged nanoparticle with ca. 140 nm of a particle size, indicating the favorable physicochemical properties for antitumor agents. Ad-HA/M-β-CyD showed the superior cytotoxic activity via CD44-mediated endosomal pathways in HCT116 cells (CD44(+)), a human colon cancer cell line. In addition, cytotoxic activity of Ad-HA/M-β-CyD was induced by apoptosis. These results suggest that Ad-HA/M-β-CyD has the potentials as a tumor-selective supramolecular antitumor agent.