DOX-loaded Micelles Research Articles

Novel Silybin-Conjugated Chitosan Polymeric Micelles for Improving the Oral Absorption of Doxorubicin Based on the Inhibition of P-gp and CYP3A4.

A drug delivery system based on silybin-conjugated chitosan (CS-SB) polymeric micelles was developed to improve the oral absorption of doxorubicin (DOX). SB was grafted to CS via succinic acid, and CS-SB was identified by 1H NMR and FT-IR. The DOX-loaded micelles were prepared by self-assembly, and the characteristics of micelles, including a small particle size of 167.8 ± 2.3 nm, a high drug loading capacity of 8.59%, and a low critical micelle concentration of 1.3 × 10-5 g/mL, were demonstrated. The micelles showed oral bioavailability of up to 193% versus DOX·HCl. The cytotoxicity test showed the biosafety of CS-SB and the potential of reductive DOX-induced cardiotoxicity. The inhibition of P-gp efflux and CYP3A4 enzyme in CS-SB micelles was confirmed by cellular uptake and enzyme activity inhibition tests. The endocytosis process of micelles was revealed by an endocytosis inhibition test. The findings exhibited the potential of CS-SB micelles in drug delivery.

Novel RGD-decorated micelles loaded with doxorubicin for targeted breast cancer chemotherapy

Nanotechnology has emerged as a promising innovative avenue for therapeutic intervention in cancer research. However, achieving satisfactory accumulation of nanoparticles in the tumor and fabricating optimized nanoparticles remain challenging. In this work, we developed a novel polymeric micelle system to actively target integrin receptors, which are usually overexpressed in breast cancer. We first synthesized a targeted peptide-modified cyclic (Arg-Gly-Asp-D-Phe-Cys) (c(RGDfc))-polyethylene glycol-acitretin amphipathic conjugate (RPA) and prepared doxorubicin (DOX)-loaded RPADm (RPA@DOX) micelles with a high drug loading content of more than 11 %. Compared with unmodified DOX-containing micelles, RPADm demonstrated increased cytotoxicity and cellular uptake by MCF-7 cells. Importantly, competitive binding experiments confirmed that the observed enhancement effect was attributed to the modification of c(RGDfc) on the surface of the micelles. Furthermore, due to its active tumor-targeting ability, compared with the other DOX-based formulations, the RPADm exhibited the highest tumor distribution and strongest therapeutic efficacy in MCF-7 tumor-bearing nude mice. Additionally, the safety evaluation experiments revealed that the DOX-loaded micelles had no obvious systemic toxicity. These results suggest that the developed micelles modified with c(RGDfc) are promising candidates for tumor-active targeting therapies.

Visible-Light-Induced Diselenide-Crosslinked Polymeric Micelles for ROS-Triggered Drug Delivery.

To synthesize an effective and versatile nano-platform serving as a promising carrier for controlled drug delivery, visible-light-induced diselenide-crosslinked polyurethane micelles were designed and prepared for ROS-triggered on-demand doxorubicin (DOX) release. A rationally designed amphiphilic block copolymer, poly(ethylene glycol)-b-poly(diselenolane diol-co-isophorone diisocyanate)-b-poly(ethylene glycol) (PEG-b-PUSe-b-PEG), which incorporates dangling diselenolane groups within the hydrophobic PU segments, was initially synthesized through the polycondensation reaction. In aqueous media, this type of amphiphilic block copolymer can self-assemble into micellar aggregates and encapsulate DOX within the micellar core, forming DOX-loaded micelles that are subsequently in situ core-crosslinked by diselenides via a visible-light-triggered metathesis reaction of Se-Se bonds. Compared with the non-crosslinked micelles (NCLMs), the as-prepared diselenide-crosslinked micelles (CLMs) exhibited a smaller particle size and improved colloidal stability. In vitro release studies have demonstrated suppressed drug release behavior for CLMs in physiological conditions, as compared to the NCLMs, whereas a burst release of DOX occurred upon exposure to an oxidation environment. Moreover, MTT assay results have revealed that the crosslinked polyurethane micelles displayed no significant cytotoxicity towards HeLa cells. Cellular uptake analyses have suggested the effective internalization of DOX-loaded crosslinked micelles and DOX release within cancer cells. These findings suggest that this kind of ROS-triggered reversibly crosslinked polyurethane micelles hold significant potential as a ROS-responsive drug delivery system.

A Triterpene-Based bioactive drug delivery system for combined chemotherapy of liver cancer

Carrier materials always account for the majority particularly in nanosized formulations, which are administrated along with the active ingredient part might result in metabolism related toxicity. The usage of bioactive excipients could not only reduce the sided effect but also provide additional therapeutic effects. In the present study, a triterpene based micellar drug delivery system was developed using a bioactive solanesol derivative. Solanesylamine was prepared firstly followed by conjugating with poly (ethylene glycol) using maleic acid amide linkage. The amphiphilic drug carrier PEGylated (2-propyl-3-methylmaleic acid)-block-solanesol amine (mPEG-CDM-NH-SOL) could be formed into micelles and loaded with doxorubicin (DOX) inside. The micelles were about 112 nm in size and the drug loading content was about 5.97 wt%. An acid triggered drug release behavior was obviously observed for the DOX loaded pH-sensitive micelle mPEG-CDM-NH-SOL-DOX. While not for DOX-loaded micelles without pH-sensitivity (mPEG-NHS-NH-SOL). CCK8 assay showed that the micelles of PEGylated solanesylamines exhibited certain inhibitory effect on tumor cells at high concentration and the pH sensitive ones seemed more toxic. In vivo studies showed that the pH sensitive mPEG-CDM-NH-SOL-DOX had a superior anti-tumor effect, indicating its great potential in cancer treatment.

Hydrophilically-modified poly(ε-caprolactone) with zwitterionic sulfobetaine/tertiary amine and their self-assemblies in water

To achieve hydrophilic modification of poly(ε-caprolactone) (PCL), a series of amphiphilic copolymers, poly(ε-caprolactone)-b-poly(N,N-dimethylaminoethyl methacrylate-co-sulfobetaine methacrylate) (PCDSs), were synthesized with varying sulfobetaine compositions using a three-step synthetic strategy. Firstly, the hydroxyl-terminated polymer, PDMAEMA-OH was synthesized through free radical polymerization using AIBN as an initiator and 2-mercaptoethanol as a chain transfer agent. Subsequently, the block copolymer poly(ε-caprolactone)-b- poly(N,N-dimethylamino ethylmethacrylate) (PCD) was prepared through ring-opening polymerization of PDMAEMA-OH and ε-caprolactone employing Sn(OCt)2 as the catalyst. Finally, zwitterionization of the tertiary amine groups in PCD was achieved by treating it with 1,3-propane sultone (1,3-PS) in THF to obtain the desired PCDSs copolymers. The chemical compositions and the structures of PCDSs were confirmed by 1H nuclear magnetic resonance (1H NMR) spectroscopy and gel permeation chromatography (GPC). Additionally, self-assembly behavior in water was systematically investigated for both PCD and PCDSs copolymers. The results showed that these copolymers could form stable, pH-responsive micelles with diameters less than 150 nm via solvent evaporation method while also exhibiting efficient loading and release capabilities for the anti-tumor drug doxorubicin (DOX). Furthermore, cytotoxicity assay revealed low cell cytotoxicity of PCDS micelles towards L929, HeLa, and MCF-7 cells; however DOX-loaded PCDS micelles (PCDS/DOX), particularly those composed of 47% sulfobetaine content exhibited significant inhibitory effects on HeLa and MCF-7 cells along with enhanced cellular uptake efficiency. These findings highlight that pH-responsive zwitterionic sulfobetaine-based polymeric micelles derived from the PCDSs hold great promise for effective DOX delivery.

Enhanced drug resistance suppression by serum-stable micelles from multi-arm amphiphilic block copolymers and tocopheryl polyethylene glycol 1000 succinate.

Aim: To develop a robust drug-delivery system using multi-arm amphiphilic block copolymers for enhanced efficacy in cancer therapy. Materials & methods: Two series of amphiphilic polymer micelles, PEG-b-PCLm and PEG-b-PCLm/TPGS, were synthesized. Doxorubicin (DOX) loading into the micelles was achieved via solvent dialysis. Results: The micelles displayed excellent biocompatibility, narrow size distribution, and uniform morphology. DOX-loaded micelles exhibited enhanced antitumor efficacy and increased drug accumulation at tumor sites compared with free DOX. Additionally, 4A-PEG47-b-PCL21/TPGS micelles effectively suppressed drug-resistant MCF-7/ADR cells. Conclusion: This study introduces a novel micelle formulation with exceptional serum stability and efficacy against drug resistance, promising for cancer therapy. It highlights innovative strategies for refining clinical translation and ensuring sustained efficacy and safety in vivo.

Effect of aromatic substituents on thermoresponsive functional polycaprolactone micellar carriers for doxorubicin delivery.

Amphiphilic functional polycaprolactone (PCL) diblock copolymers are excellent candidates for micellar drug delivery. The functional groups on the backbone significantly affect the properties of PCL. A systematic investigation of the effect of aromatic substituents on the self-assembly of γ-functionalized PCLs and the delivery of doxorubicin (DOX) is presented in this work. Three thermoresponsive amphiphilic diblock copolymers with poly(γ-benzyloxy-ε-caprolactone) (PBnCL), poly(γ-phenyl- ε-caprolactone) (PPhCL), poly(γ-(4-ethoxyphenyl)-ε-caprolactone) (PEtOPhCL), respectively, as hydrophobic block and γ-tri(ethylene glycol) functionalized PCL (PME3CL) as hydrophilic block were prepared through ring-opening polymerization (ROP). The thermoresponsivity, thermodynamic stability, micelle size, morphology, DOX-loading, and release profile were determined. The LCST values of amphiphilic diblock copolymers PME3CL-b-PBnCL, PME3CL-b-PPhCL, and PME3CL-b-PEtOPhCL are 74.2°C, 43.3°C, and 37.3°C, respectively. All three copolymers formed spherical micelles in phosphate-buffered saline (PBS, 1×, pH = 7.4) at low concentrations ranging from 8.7 × 10-4g/L to 8.9 × 10-4g/L. PME3CL-b-PBnCL micelles showed the highest DOX loading capacity of 3.01 ± 0.18 (wt%) and the lowest drug release, while PME3CL-b-PEtOPhCL micelles exhibited the lowest DOX loading capacity of 1.95 ± 0.05 (wt%) and the highest drug release. Cytotoxicity and cellular uptake of all three micelles were assessed in vitro using MDA-MB-231 breast cancer cells. All three empty micelles did not show significant toxicity to the cells at concentrations high up to 0.5mg/mL. All three DOX-loaded micelles were uptaken into the cells, and DOX was internalized into the nucleus of the cells.

Tunable self-assembly of lipid-based block polymeric micelles with temperature-sensitive poly(vinylcaprolactam) shell for effective anticancer drug delivery

Lipids, as naturally occurring biomolecules have emerged as promising carriers for delivering various therapeutic agents. However, only a few attempts have been made in terms of their applications as amphiphilic block copolymers for anticancer drug delivery. In this work, a biocompatible micellar drug delivery system with fatty acid-based polymer core and temperature-sensitive shell was developed. A series of amphiphilic block copolymers poly(vinyl stearate)/poly(vinyl laurate)-b-poly(N-vinylcaprolactam) (PVS/PVL-b-PNVCL) were synthesized via microwave-assisted reversible addition-fragmentation chain transfer polymerization in a controlled fashion. By varying the fatty acid type and hydrophilic/hydrophobic block lengths, the self-assembly behaviour of the block copolymer micelles proved to be highly tunable in terms of their morphology and particle size. Nile Red and hydrophobic anticancer drug doxorubicin (DOX) were effectively incorporated into the micelles, demonstrating high drug loading capacity, good serum stability, and temperature-dependent drug release characteristics of the polymeric micelles. In vitro studies using cell models revealed that blank PVS -b-PNVCL micelles are biocompatible with different cell lines, while DOX-loaded micelles were internalized into and accumulated in the cells, showing a high cytotoxic effect against HeLa cells. These findings suggest an opportunity for the development of safe and efficient lipid-based micellar system for smart drug delivery and cancer treatments.

Visible light and pH-responsive star copolymer and doxorubicin-polymer conjugate micelles for combination drug delivery and bioimaging

Amphiphilic 3-arm star copolymer containing visible light-cleavable BODIPY group and pH-responsive imine bonds at the junction of hydrophilic poly(ethylene glycol) (PEG) and two poly(ε-caprolactone) (PCL) arms was synthesized by the combination of ring-opening polymerization (ROP) and click chemistry. The formation and stimuli-responsive disruption of micelles were analyzed using dynamic light scattering and transmission electron microscopy. Dual stimuli-responsive release of anticancer drugs Doxorubicin (Dox) and Camptothecin (CPT) from the micelles was studied. Micellar assemblies containing Dox conjugated to PEG-BODIPY through imine bonds were prepared and controlled release of Dox in response to visible light and pH was shown. CPT and Dox-loaded star copolymer micelles as well as CPT loaded Dox-conjugated micelles were used in cellular uptake studies on MDA-MB 231 cells, and the synergistic effect of the two stimuli on the release of the two drugs was demonstrated inside the cells. Micellar assemblies also showed excellent bioimaging properties in the cellular uptake studies.

Maleimide functionalized polycaprolactone micelles for glutathione quenching and doxorubicin delivery.

High glutathione production is known to be one of the defense mechanisms by which many cancer cells survive elevated oxidative stress. By explicitly targeting glutathione in these cancer cells and diminishing its levels, oxidative stress can be intensified, ultimately triggering apoptosis or programmed cell death. Herein, we developed a novel approach by creating maleimide-functionalized polycaprolactone polymers, specifically using 2,3-diiodomaleimide functionality to reduce the level of glutathione in cancer cells. Polycaprolactone was chosen to conjugate the 2,3-diiodomaleimide functionality due to its biodegradable and biocompatible properties. The amphiphilic block copolymer was synthesized using PEG as a macroinitiator to make corresponding polymeric micelles. The resulting 2,3-diiodomaleimide-conjugated polycaprolactone micelles effectively quenched glutathione, even at low concentrations (0.01 mg mL-1). Furthermore, we loaded these micelles with the anticancer drug doxorubicin (DOX), which exhibited pH-dependent drug release. We obtained a loading capacity (LC) of 3.5% for the micelles, one of the highest LC reported among functional PCL-based micelles. Moreover, the enhanced LC doesn't affect their release profile. Cytotoxicity experiments demonstrated that empty and DOX-loaded micelles inhibited cancer cell growth, with the DOX-loaded micelles displaying the highest cytotoxicity. The ability of the polymer to quench intracellular GSH was also confirmed. This approach of attaching maleimide to polycaprolactone polymers shows promise in depleting elevated glutathione levels in cancer cells, potentially improving cancer treatment efficacy.

Effect of Hydrophobic Chain Length in Amphiphilic Chitosan Conjugates on Intracellular Drug Delivery and Smart Drug Release of Redox-Responsive Micelle.

Three redox-sensitive nanocarriers were rationally designed based on amphiphilic low molecular weight chitosan-cystamine-octylamine/dodecylamin/cetylamine (LC-Cys-OA, LC-Cys-DA, LC-Cys-CA) conjugates containing disulfide linkage for maximizing therapeutic effect by regulating hydrophobic interaction. The resultant spherical micelles had the characteristics of low CMC, suitable size, excellent biosafety and desired stability. The drug-loaded micelles were fabricated by embedding doxorubicin (Dox) into the hydrophobic cores. The effect of hydrophobic chain lengths of amphiphilic conjugates on encapsulation capacity, redox sensitivity, trigger-release behavior, cellular uptake efficacy, antitumor effect and antimigratory activity of Dox-loaded micelles was systematically investigated. Studies found that Dox-loaded LC-Cys-CA micelle had superior loading capacity and enhanced redox sensitivity compared with the other two micelles. Release assay indicated that the three Dox-loaded micelles maintained sufficiently stability in normal blood circulation but rapidly disintegrated in tumor cells. More importantly, the LC-Cys-CA micelle with a longer hydrophobic chain length exhibited a higher accumulative Dox release percentage than the other two micelles. Additionally, an increase in hydrophobic chain lengths of amphiphilic conjugates improved cellular uptake efficiency, antitumor effect and antimigration activity of Dox-loaded micelles, which could be explained by enhanced loading ability and redox sensitivity. Our research was expected to provide a viable platform for achieving a desired therapeutic efficacy via the alteration of hydrophobic interaction.

ROS-responsive core crosslinked micelles by combination of enzymatic polymerization and thiol-ene click chemistry for anticancer drug delivery

The reactive oxygen species (ROS) responsive amphiphilic poly(ethylene glycol)-b-poly(thioketal) (mPEG-b-PTK) copolymer was synthesized by enzyme-catalyzed polymerization for the first time. Core crosslinked (CCL) micelles were prepared via thiol-ene click reaction between the double bond of the side chain of mPEG-b-PTK and the thiol group of pentaerythritol tetrakis (3-mercaptopropionate) as a crosslinker under UV light. The success of crosslinking was verified by NMR and IR. CCL micelles showed better stability in stability against dilution and storage stability experiments compared with the uncrosslinked (UCL) micelles. The ROS-responsiveness of CCL micelles was characterized by DLS, TEM, NMR, AFM and SEM. In vitro release studies, CCL micelles encapsulating doxorubicin (DOX) showed a faster release rate of nearly 100% within 32 h in PBS containing 5 mM H2O2 compared to the control without H2O2. Cytotoxicity test demonstrated good biocompatibility of CCL micelles and low toxicity with cell viability above 82% and 86% in HeLa cells and HUVEC cells, respectively. And CCL DOX-loaded micelles exhibited great anticancer activity with IC50 value about 4.8 mg/L for Hela cells. Finally, flow cytometry and confocal laser scanning microscope (CLSM) showed that DOX-loaded micelles had excellent internalization efficiency in HeLa cells. The obtained ROS-responsive CCL micelles held promise for anticancer drug delivery.

Injectable Hydrogels of Amphiphilic Vitamin E Derivatives for Locoregional Chemotherapy.

Vitamin E derivatives are particularly effective in chemotherapy drug development because they are nontoxic, biocompatible, and selective. Among them, α-tocopheryl succinate (α-TOS) can act synergistically with some chemotherapeutic agents. However, its hydrophobicity limits its systemic administration, and localized formulations are not available. Herein, we developed an injectable hydrogel based on self-assembled micelles of a triblock amphiphilic derivative of α-TOS (PEG-2VES), in which doxorubicin (DOX) was encapsulated in the core of the micelles for combined chemotherapy. A molecule of α-TOS was grafted onto each end of poly(ethylene glycols) (PEGs) of different lengths. Hydrogels were prepared by dissolving the polymers or the DOX-loaded micelles in water at room temperature. The subcutaneously injected hydrogels kept their shape and sustainably released the payloads over 7 days without any noticeable inflammatory response. In vitro and in vivo results confirmed the synergistic antitumor effects of the hydrogel and loaded drug. Furthermore, DOX-loaded hydrogels showed greater therapeutic efficiency and fewer toxic side effects than DOX alone. Overall, this hydrogel acts as a multifunctional system that can deliver drug, improve the therapeutic effect, and minimize drug toxicity.

A Novel NQO1 Enzyme-Responsive Polyurethane Nanocarrier for Redox-Triggered Intracellular Drug Release.

The design of nano-drug delivery vehicles responsive to tumor microenvironment stimuli has become a crucial aspect in developing cancer therapy in recent years. Among them, the enzyme-responsive nano-drug delivery system is particularly effective, as it utilizes tumor-specific and highly expressed enzymes as precise targets, leading to increased drug release at the target sites, reduced nonspecific release, and improved efficacy while minimizing toxic side effects on normal tissues. NAD(P)H:quinone oxidoreductase 1 (NQO1) is an important reductase associated with cancer and is overexpressed in some cancer cells, particularly in lung and breast cancer. Thus, the design of nanocarriers with high selectivity and responsiveness to NQO1 is of great significance for tumor diagnosis and treatment. It has been reported that under physiological conditions, NQO1 can specifically reduce the trimethyl-locked benzoquinone structure through a two-electron reduction, resulting in rapid lactonization via an enzymatic reaction. Based on this, a novel reduction-sensitive polyurethane (PEG-PTU-PEG) block copolymer was designed and synthesized by copolymerizing diisocyanate, a reduction-sensitive monomer (TMBQ), and poly(ethylene glycol). The successful synthesis of monomers and polymers was verified by nuclear magnetic resonance (1H NMR) and gel permeation chromatography (GPC). Then, the PEG-PTU-PEG micelles were successfully prepared by self-assembly, and their reductive dissociation behavior in the presence of Na2S2O4 was verified by dynamic light scattering (DLS), 1H NMR, and GPC. Next, the model drug doxorubicin (DOX) was encapsulated into the hydrophobic core of this polyurethane micelles by microemulsion method. It was observed that the drug-loaded micelles could also achieve a redox response and rapidly release the encapsulated substances. In vitro cell experiments demonstrated that PEG-PTU-PEG micelles had good biocompatibility and a low hemolysis rate (<5%). Furthermore, in the presence of an NQO1 enzyme inhibitor (dicoumarol), lower drug release from micelles was observed in A549 and 4T1 cells by both fluorescence microscopy and flow cytometry assays, but not in NIH-3T3 control cells. Predictably, DOX-loaded micelles also showed lower cytotoxicity in 4T1 cells in the presence of NQO1 enzyme inhibitors. These results indicate that drug-loaded polyurethane micelles could accomplish specific drug release in the reducing environment in the presence of NQO1 enzymes. Therefore, this study provides a new option for the construction of polyurethane nanocarriers for precise targeting and reductive release, which could benefit the intracellular drug-specific release and precision therapy of tumors.

Zwitterionic Targeting Doxorubicin -Loaded Micelles Assembled by Amphiphilic Dendrimers with Enhanced Antitumor Performance

Chemotherapy is the main method of treating malignant tumors in clinical treatment. However, the commonly used chemotherapeutic drugs have the disadvantages of high biological toxicity, poor water solubility, low targeting ability, and high side effects. Zwitterionic micelles assembled by amphiphilic dendrimers modified with zwitterionic groups and targeting ligand should largely overcome these shortcomings. Herein, the zwitterionic group and targeting peptide c(RGDfC) were modified on the surface of generation 2 poly(propylene imine) dendrimers (G2 PPI), which was conjugated with hydrophobic N-(2-mercaptoethyl) oleamide to form amphiphilic dendrimers (PPIMYRC). PPIMYRC self-assembled into micelles with doxorubicin (DOX) loaded in the interior of micelles to prepare DOX-loaded micelles (PPIMYRC-DOX micelles). The PPIMYRC-DOX micelles had great stability in fibrinogen and pH-responsive drug release. Furthermore, PPIMYRC-DOX micelles had higher cellular uptake rates than free DOX, resulting in higher cytotoxicity of PPIMYRC-DOX micelles than that of free DOX. More importantly, PPIMYRC-DOX micelles inhibited tumors much better than free DOX. The tumor inhibition rate of PPIMYRC-DOX micelles was as high as 93%. Taken together, PPIMYRC-DOX micelles were assembled by amphiphilic dendrimers with the zwitterionic and targeting groups, which enhanced the therapeutic effect of DOX and reduced its side effects. The prepared targeting nanodrug has great potential for further application in antitumor therapy.

Redox-Responsive Core-Cross-Linked Micelles of Miktoarm Poly(ethylene oxide)-b-poly(furfuryl methacrylate) for Anticancer Drug Delivery.

The physiological instability of nanocarriers, premature drug leakage during blood circulation, and associated severe side effects cause compromised therapeutic efficacy, which have significantly hampered the progress of nanomedicines. The cross-linking of nanocarriers while keeping the effectiveness of their degradation at the targeted site to release the drug has emerged as a potent strategy to overcome these flaws. Herein, we have designed novel (poly(ethylene oxide))2-b-poly(furfuryl methacrylate) ((PEO2K)2-b-PFMAnk) miktoarm amphiphilic block copolymers by coupling alkyne-functionalized PEO (PEO2K-C≡H) and diazide-functionalized poly(furfuryl methacrylate) ((N3)2-PFMAnk) via click chemistry. (PEO2K)2-b-PFMAnk self-assembled to form nanosized micelles (mikUCL) with hydrodynamic radii in the range of 25∼33 nm. The hydrophobic core of mikUCL was cross-linked by a disulfide-containing cross-linker using the Diels-Alder reaction to avoid unwanted leakage and burst release of a payload. As expected, the resulting core-cross-linked (PEO2K)2-b-PFMAnk micelles (mikCCL) exhibited superior stability under a normal physiological environment and were de-cross-linked to rapidly release doxorubicin (DOX) upon exposure to a reduction environment. The micelles were compatible with HEK-293 normal cells, while DOX-loaded micelles (mikUCL/DOX and mikCCL/DOX) induced high antitumor activity in HeLa and HT-29 cells. mikCCL/DOX preferentially accumulated at the tumor site and was more efficacious than free DOX and mikUCL/DOX for tumor inhibition in HT-29 tumor-bearing nude mice.

Systematic Design and Study of Star-like Polymeric Prodrug Unimolecular Micelles β-CD-P[CL-co-(ACL-g-DOX)-SS-MPEG]21 by DPD Simulations.

Unimolecular micelles composed of a single polymeric molecule have recently attracted significant attention in anti-cancer drug delivery due to their high thermodynamic stability and small particle sizes. Applying the prodrug strategy to unimolecular micelles may provide superior nano-drug carriers with simultaneous high stability, low drug leakage, and well-drug loading capacity. However, the formation mechanism of the unimolecular prodrug micelles, the superiority of the prodrug strategy, as well as the prodrug controlled release mechanism were scantily understood at the mesoscopic scale. In this work, dissipative particle dynamics mesoscopic simulations were employed to investigate the self-assembly behavior, formation conditions, drug distribution regularities, and the prodrug release process of the star-like polymeric prodrug unimolecular micelles formed by β-CD-P[CL-co-(ACL-g-DOX)-SS-MPEG]21. A special bond-breaking script was used to accomplish the bond-breaking simulation of the grafted DOX bonds and the disulfide bonds. Results showed that to form well monodispersed and superior DOX-loaded unimolecular micelles, the polymer concentration should be well controlled at low volume fractions (≤10.59%), and the detailed molecular structure of the polymer was suggested as β-cyclodextrin-P[caprolactone-co-(amino caprolactone-g-doxorubicin)-disulfide-methyl polyethylene glycol]21) (β-CD-P[CL30-co-(ACL-g-DOX)8-SS-MPEG49]21). By comparison with the DOX physically loaded micelles, it was found that the prodrug unimolecular micelles with DOX grafted on the polymer displayed no drug leakage and superior drug loading capacity. Simulations on the prodrug release process showed that the prodrug unimolecular micelles assembled by β-CD-P[CL30-co-(ACL-g-DOX)8-SS-MPEG49]21 would provide good dual pH/reduction-responsive DOX release performance.

Structural Engineering of Star Block Biodegradable Polymer Unimolecular Micelles for Drug Delivery in Cancer Cells.

The present investigation reports the structural engineering of biodegradable star block polycaprolactone (PCL) to tailor-make aggregated micelles and unimolecular micelles to study their effect on drug delivery aspects in cancer cell lines. Fully PCL-based star block copolymers were designed by varying the arm numbers from two to eight while keeping the arm length constant throughout. Multifunctional initiators were exploited for stepwise solvent-free melt ring-opening polymerization of ε-caprolactone and γ-substituted caprolactone to construct star block copolymers having a PCL hydrophobic core and a carboxylic PCL hydrophilic shell, respectively. A higher arm number and a higher degree of branching in star polymers facilitated the formation of unimolecular micelles as opposed to the formation of conventional multimicellar aggregates in lower arm analogues. The dense core of the unimolecular micelles enabled them to load high amounts of the anticancer drug doxorubicin (DOX, ∼12-15%) compared to the aggregated micelles (∼3-4%). The star unimolecular micelle completely degraded leading to 90% release of the loaded drug upon treatment with the lysosomal esterase enzyme in vitro. The anticancer efficacies of these DOX-loaded unimolecular micelles were tested in a breast cancer cell line (MCF-7), and their IC50 values were found to be much lower compared to those of aggregated micelles. Time-dependent cellular uptake studies by confocal microscopy revealed that unimolecular micelles were readily taken up by the cells, and enhancement of the drug concentration was observed at the intracellular level up to 36 h. The present work opens new synthetic strategies for building a next-generation biodegradable unimolecular micellar nanoplatform for drug delivery in cancer research.

Phosphorous Dendron Micelles as a Nanomedicine Platform for Cooperative Tumor Chemoimmunotherapy via Synergistic Modulation of Immune Cells.

Design of effective nanomedicines to modulate multiple immune cells to overcome the immune-suppressive tumor microenvironment is desirable to improve the overall poor clinical outcomes of immunotherapy. Herein, a nanomedicine platform is reported based on chemotherapeutic drug doxorubicin (DOX)-loaded phosphorus dendron micelles (M-G1-TBPNa@DOX, TBP, tyramine bearing two dimethylphosphonate) with inherent immunomodulatory activity for synergistic tumor chemoimmunotherapy. The M-G1-TBPNa@DOX micelles with good stability and a mean particle size of 86.4 nm can deliver DOX to solid tumors to induce significant tumor cell apoptosis and immunogenic cell death (ICD). With the demonstrated intrinsic activity of M-G1-TBPNa that can promote the proliferation of natural killer (NK) cells, the ICD-resulted maturation of dendritic cells of the DOX-loaded micelles, and the combination of anti-PD-L1 antibody, the synergistic modulation of multiple immune cells through NK cell proliferation, recruitment of tumor-infiltrating NK cells and cytotoxic T cells, and decrease of regulatory T cells for effective tumor chemoimmunotherapy with strong antitumor immunity and immune memory effect for effective prevention of lung metastasis are demonstrated. The developed phosphorous dendron micelles may hold great promise to be used as an advanced nanomedicine formulation for synergistic modulation of multiple immune cells through NK cell proliferation for effective chemoimmunotherapy of different tumor types.

Enhanced Immunogenic Cell Death by Apoptosis/Ferroptosis Hybrid Pathway Potentiates PD-L1 Blockade Cancer Immunotherapy.

Even though chemotherapy regimens for treating cancer by inducing apoptosis are extensively utilized, their therapeutic effect is hindered by multiple limitations. Thus, a combination of other types of anticancer modalities is urgently needed. Herein, a tannic acid (TA)-Fe3+-coated doxorubicin (DOX)-encapsulated 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(poly(ethylene glycol))-2000] (ammonium salt) (DSPE-PEG) micelle (TFDD) for apoptosis/ferroptosis-mediated immunogenic cell death (ICD) is reported. By coating TA-Fe3+ on the surface of DOX-loaded micelles, an apoptotic agent and a ferroptotic agent are simultaneously delivered into the cancer cells and induce cell death. Furthermore, the intracellular oxidative environment generated by the apoptosis/ferroptosis hybrid pathway stimulates the endoplasmic reticulum (ER) and leads to ICD induction. The in vivo results show that the combination treatment of TFDD and anti-programmed death-ligand 1 antibodies (anti-PD-L1) considerably inhibits tumor growth and improves antitumor immunity by activating CD4+ and CD8+ T cells and decreasing the ratio of regulatory T cells (Treg) to CD4+ T cells. This study suggests that the apoptosis/ferroptosis-mediated ICD inducer may offer a potent strategy for enhanced cancer immunotherapy.