A Copper-Mediated Disulfiram-Loaded pH-Triggered PEG-Shedding TAT Peptide-Modified Lipid Nanocapsules for Use in Tumor Therapy

Nanomedicine-based disulfiram and metal ion co-delivery strategies for cancer treatment

Disulfiram (DSF) is a second-line drug for the clinical treatment of alcoholism and has long been proven to be safe for use in clinical practice. In recent years, researchers have discovered the cancer-killing activity of DSF, which is highly dependent on the presence of metal ions, particularly copper ions. Additionally, free DSF is highly unstable and easily degraded within few minutes in blood circulation. Therefore, an ideal DSF formulation should facilitate the co-delivery of metal ions and safeguard the DSF throughout its biological journey before reaching the targeted site. Extensive research have proved that nanotechnology based formulations can effectively realize this goal by strategic encapsulation therapeutic agents within nanoparticle. To be more specific, this is accomplished through precise delivery, coordinated release of metal ions at the tumor site, thereby amplifying its cytotoxic potential. Beyond traditional co-loading techniques, innovative approaches such as DSF-metal complex and metal nanomaterials, have also demonstrated promising results at the animal model stage. This review aims to elucidate the anticancer mechanism associated with DSF and its reliance on metal ions, as well as to provide a comprehensive overview of recent advances in the arena of nanomedicine based co-delivery strategies for DSF and metal ion in the context of cancer therapy.

Bridging Smart Nanosystems with Clinically Relevant Models and Advanced Imaging for Precision Drug Delivery

Intracellular delivery of nano-drug-carriers (NDC) to specific cells, diseased regions, or solid tumors has entered the era of precision medicine that requires systematic knowledge of nano-biological interactions from multidisciplinary perspectives. To this end, this review first provides an overview of membrane-disruption methods such as electroporation, sonoporation, photoporation, microfluidic delivery, and microinjection with the merits of high-throughput and enhanced efficiency for in vitro NDC delivery. The impact of NDC characteristics including particle size, shape, charge, hydrophobicity, and elasticity on cellular uptake are elaborated and several types of NDC systems aiming for hierarchical targeting and delivery in vivo are reviewed. Emerging in vitro or ex vivo human/animal-derived pathophysiological models are further explored and highly recommended for use in NDC studies since they might mimic in vivo delivery features and fill the translational gaps from animals to humans. The exploration of modern microscopy techniques for precise nanoparticle (NP) tracking at the cellular, organ, and organismal levels informs the tailored development of NDCs for in vivo application and clinical translation. Overall, the review integrates the latest insights into smart nanosystem engineering, physiological models, imaging-based validation tools, all directed towards enhancing the precise and efficient intracellular delivery of NDCs.

Intelligent responsive copper-diethyldithiocarbamate-based multifunctional nanomedicine for photothermal-augmented synergistic cancer therapy

The design of multifunctional nanomedicine through the combination of multimodal treatments to achieve the optimal antitumor effect is essential for cancer therapy. Herein, we design and develop a multifunctional theranostic nanoplatform using an iron ion-doxorubicin (DOX) nanoscale coordination polymer (Fe/DOX NCP) as a shell coating on the surface of polyvinyl pyrrolidone (PVP) stabilized copper-diethyldithiocarbamate nanoparticles (Cu(DDC)2 NPs) for combined tumor chemo-/photothermal/chemodynamic therapy. The obtained Cu(DDC)2@Fe/DOX NPs display pH/laser dual-responsive degradation behavior and also exhibit favorable photothermal performance. Under 808 nm laser irradiation, Cu(DDC)2@Fe/DOX NPs can convert light into heat, which not only kills tumor cells via hyperthermia in photothermal therapy (PTT), but also accelerates the degradation of Fe/DOX NCPs to release Fe3+ and DOX. The liberated Fe3+ can be used to catalyze hydrogen peroxide via the Fenton reaction to produce highly toxic hydroxyl radicals (˙OH) in chemodynamic therapy (CDT). The released DOX and the exposed Cu(DDC)2 can cause significant cell death in combined chemotherapy via a superimposed effect. In vitro and in vivo results prove that Cu(DDC)2@Fe/DOX NPs with laser irradiation present remarkable anticancer performances in hyperthermia-enhanced chemo-/CDT. Therefore, this study provides a new strategy for highly efficient synergistic cancer therapy.

A disulfiram/copper gluconate co-loaded bi-layered long-term drug delivery system for intraperitoneal treatment of peritoneal carcinomatosis

To develop a long-term drug delivery system for the treatment of primary and metastatic peritoneal carcinoma (PC) by intraperitoneal (IP) injection, a disulfiram (DSF)/copper gluconate (Cu-Glu)-co-loaded bi-layered poly (lactic acid-coglycolic acid) (PLGA) microspheres (Ms) - thermosensitive hydrogel system (DSF-Ms-Cu-Glu-Gel) was established. Rate and mechanisms of drug release from DSF-Ms-Cu-Glu-Gel were explored. The anti-tumor effects of DSF-Ms-Cu-Glu-Gel by IP injection were evaluated using H22 xenograft tumor model mice. The accumulative release of DSF from Ms on the 10th day was 83.79% without burst release. When Ms were dispersed into B-Gel, burst release at 24 h decreased to 14.63%. The results showed that bis (diethyldithiocarbamate)-copper (Cu(DDC)2) was formed in DSF-Ms-Cu-Glu-Gel and slowly released from B-Gel. In a pharmacodynamic study, the mount of tumor nodes and ascitic fluid decreased in the DSF-Ms-Cu-Glu-Gel group. This was because: (1) DSF-Ms-Cu-Glu-Gel system co-loaded DSF and Cu-Glu, and physically isolated DSF and Cu-Glu before injection to protect DSF; (2) space and water were provided for the formation of Cu(DDC)2; (3) could provide an effective drug concentration in the abdominal cavity for a long time; (4) both DSF and Cu(DDC)2 were effective anti-tumor drugs, and the formation of Cu(DDC)2 occurred in the abdominal cavity, which further enhanced the anti-tumor activity. Thus, the DSF-Ms-Cu-Glu-Gel system can be potentially used for the IP treatment of PC in the future.

The mechanism of copper transporters in ovarian cancer cells and the prospect of cuproptosis

Copper transporters can not only carry copper (Cu) to maintain the homeostasis of Cu in cells but also transport platinum-based chemotherapy drugs. The effect of copper transporters on chemosensitivity has been demonstrated in a variety of malignancies. In addition, recent studies have reported that copper transporters can act as vectors to induce cuproptosis. Therefore, copper transporters can act on cells through different mechanisms to achieve different purposes. This review mainly describes the current research progress of the intracellular transport mechanism of copper transporters and cuproptosis, and prospects for the application of them in the treatment of ovarian cancer (OC).

The immunomodulatory function and antitumor effect of disulfiram: paving the way for novel cancer therapeutics

More than 60 years ago, disulfiram (DSF) was employed for the management of alcohol addiction. This promising cancer therapeutic agent inhibits proliferation, migration, and invasion of malignant tumor cells. Furthermore, divalent copper ions can enhance the antitumor effects of DSF. Molecular structure, pharmacokinetics, signaling pathways, mechanisms of action and current clinical results of DSF are summarized here. Additionally, our attention is directed towards the immunomodulatory properties of DSF and we explore novel administration methods that may address the limitations associated with antitumor treatments based on DSF. Despite the promising potential of these various delivery methods for utilizing DSF as an effective anticancer agent, further investigation is essential in order to extensively evaluate the safety and efficacy of these delivery systems.

Co-delivery of a tumor microenvironment-responsive disulfiram prodrug and CuO2 nanoparticles for efficient cancer treatment

Disulfiram (DSF) has been used as a hangover drug for more than seven decades and was found to have potential in cancer treatment, especially mediated by copper. However, the uncoordinated delivery of disulfiram with copper and the instability of disulfiram limit its further applications. Herein, we synthesize a DSF prodrug using a simple strategy that could be activated in a specific tumor microenvironment. Poly amino acids are used as a platform to bind the DSF prodrug through the B-N interaction and encapsulate CuO2 nanoparticles (NPs), obtaining a functional nanoplatform Cu@P-B. In the acidic tumor microenvironment, the loaded CuO2 NPs will produce Cu2+ and cause oxidative stress in cells. At the same time, the increased reactive oxygen species (ROS) will accelerate the release and activation of the DSF prodrug and further chelate the released Cu2+ to produce the noxious copper diethyldithiocarbamate complex, which causes cell apoptosis effectively. Cytotoxicity tests show that the DSF prodrug could effectively kill cancer cells with only a small amount of Cu2+ (0.18 μg mL-1), inhibiting the migration and invasion of tumor cells. In vitro and in vivo experiments have demonstrated that this functional nanoplatform could kill tumor cells effectively with limited toxic side effects, showing a new perspective in DSF prodrug design and cancer treatment.

Advancing Cancer Therapy with Copper/Disulfiram Nanomedicines and Drug Delivery Systems

Disulfiram (DSF) is a thiocarbamate based drug that has been approved for treating alcoholism for over 60 years. Preclinical studies have shown that DSF has anticancer efficacy, and its supplementation with copper (CuII) significantly potentiates the efficacy of DSF. However, the results of clinical trials have not yielded promising results. The elucidation of the anticancer mechanisms of DSF/Cu (II) will be beneficial in repurposing DSF as a new treatment for certain types of cancer. DSF's anticancer mechanism is primarily due to its generating reactive oxygen species, inhibiting aldehyde dehydrogenase (ALDH) activity inhibition, and decreasing the levels of transcriptional proteins. DSF also shows inhibitory effects in cancer cell proliferation, the self-renewal of cancer stem cells (CSCs), angiogenesis, drug resistance, and suppresses cancer cell metastasis. This review also discusses current drug delivery strategies for DSF alone diethyldithocarbamate (DDC), Cu (II) and DSF/Cu (II), and the efficacious component Diethyldithiocarbamate-copper complex (CuET).

Overcoming drug resistance with a docetaxel and disulfiram loaded pH-sensitive nanoparticle

Previous studies have demonstrated that breast cancer cells deploy a myriad array of strategies to thwart the activity of anticancer drugs like docetaxel (DTX), including acquired drug resistance due to overexpression of drug-efflux pumps like P-glycoprotein (P-gp) and innate drug resistance by cancer stem cells (CSCs). As disulfiram (DSF) can inhibit both P-gp and CSCs, we hypothesized that co-treatment of DTX and DSF could sensitize the drug-resistant breast cancer cells. To deliver a fixed dose ratio of DTX and DSF targeted to the tumor, a tumor extracellular pH-responsive nanoparticle (NP) was developed using a histidine-conjugated star-shaped PLGA with TPGS surface decoration ([DD]NpH-T). By releasing the encapsulated drugs in the tumor microenvironment, pH-sensitive NPs can overcome the tumor stroma-based resistance against nanomedicines. In in-vitro studies, [DD]NpH-T exhibited increased drug release at pH 6.8, improved penetration in a 3D tumor spheroid, reduced serum protein adsorption, and enhanced cytotoxic efficacy against both innate and acquired DTX-resistant breast cancer cells. In in-vivo studies, a significant increase in plasma AUC and tumor drug delivery was observed with [DD]NpH-T, which resulted in an enhanced in-vivo anti-tumor efficacy against a mouse orthotopic breast cancer, with a significantly increased intratumoral ROS and apoptosis, while decreasing P-gp expression and prevention of lung metastasis. Altogether, the current study demonstrated that the DTX and DSF combination could effectively target multiple drug-resistance pathways in-vitro, and the in-vivo delivery of this drug combination using TPGS-decorated pH-sensitive NPs could increase tumor accumulation, resulting in improved anti-tumor efficacy.

Peptide-Based siRNA Nanocomplexes Targeting Hepatic Stellate Cells

Liver fibrosis is the excessive accumulation of extracellular matrix (ECM) in the liver due to chronic injuries and inflammation. These injuries activate and transform quiescent hepatic stellate cells (HSCs) into proliferative myofibroblast-like cells, which are the key contributors to the secretin of ECM in the fibrotic liver. The insulin-like growth factor 2 receptor (IGF2R) is a multifunctional receptor that is overexpressed on activated HSCs and is a specific molecular marker of activated HSCs in the fibrotic liver. We recently discovered an IGF2R-specific peptide that significantly increases the binding affinity and uptake of a protein-based siRNA nanocomplex to activated HSCs. However, there is a potential concern about the immunogenicity of protein-based siRNA delivery systems. In this study, we used the IGF2R-specific peptide to modify a small peptide-based siRNA nanocomplex for HSC-specific drug delivery. We incorporated a short spacer and glutamate residues into the IGF2R peptides. The siRNA nanocomplex modified with the IGF2R-3GK6E peptide demonstrated higher HSC specificity compared to an unmodified nanocomplex. This peptide-based nanocomplex provides a promising platform to effectively deliver Pcbp2 siRNA to activated HSCs for the treatment of liver fibrosis.

Buffet-style Cu(II) for enhance disulfiram-based cancer therapy

Studies have shown that disulfiram (DSF) can combine with Cu²⁺ to form bis(N, N-diethyldithiocarbamate) copper(II) complex (CuET) as antitumor drugs. However, there is insufficient endogenous Cu²⁺ dose to eradicate cancer cells selectively. Inspired by the buffet, we use Cu²⁺ doped hollow zeolitic imidazolate framework nanoparticles (HZIF_Cu) as the carrier and equipped with DSF and indocyanine green (ICG) and targeted by folic acid (FA) (D&I@HZIF_Cu-FA) to enhance DSF-based cancer therapy. D&I@HZIF_Cu-FA could effectively supply Cu²⁺ by a buffet-style, assisting the "DSF-to-CuET" transformation in the tumor. Additionally, self-supply Cu²⁺ could convert H₂O₂ into ·OH by triggering a Fenton-like reaction for chemo-dynamic therapy, and ICG achieves photothermal therapy for tumors under laser irradiation. This work provides a buffet-style for Cu²⁺ to make DSF a strong candidate for cancer treatment by combining chemotherapy, chemo-dynamic therapy, and photothermal therapy and inspires more research about its applications in tumor therapy.

Anticancer effects of disulfiram: a systematic review of in vitro, animal, and human studies

BACKGROUND AND OBJECTIVES

Cancer morbidity and mortality rates remain high, and thus, at present, considerable efforts are focused on finding drugs with higher sensitivity against tumor cells and fewer side effects. Disulfiram (DSF), as an anti-alcoholic drug, kills the cancer cells by inducing apoptosis. Several preclinical and clinical studies have examined the potential of repurposing DSF as an anticancer treatment. This systematic review aimed to assess evidence regarding the antineoplastic activity of DSF in in vitro and in vivo models, as well as in humans.

METHODS

Two authors independently conducted this systematic review of English and Chinese articles from the PubMed, Embase, and the Cochrane Library databases up to July 2019. Eligible in vitro studies needed to include assessments of the apoptosis rate by flow cytometry using annexin V/propidium iodide, and studies in animal models and clinical trials needed to examine tumor inhibition rates, and progression-free survival (PFS) and overall survival (OS), respectively. Data were analyzed using descriptive statistics.

RESULTS

Overall, 35 studies, i.e., 21 performed in vitro, 11 based on animal models, and three clinical trials, were finally included. In vitro and animal studies indicated that DSF was associated with enhanced apoptosis and tumor inhibition rates, separately. Human studies showed that DSF prolongs PFS and OS. The greatest anti-tumor activity was observed when DSF was used as combination therapy or as a nanoparticle-encapsulated molecule. There was no noticeable body weight loss after DSF treatment, which indicated that there was no major toxicity of DSF.

CONCLUSIONS

This systematic review provides evidence regarding the anti-tumor activity of DSF in vitro, in animals, and in humans and indicates the optimal forms of treatment to be evaluated in future research.

Copper (Ⅱ)/cis-platinum -loaded nanogels as an adjuvant potentiate disulfiram antitumor efficacy

Disulfiram (DSF) is nontoxic and exerts anticancer activity by forming highly toxic chelate via its metabolite diethyldithiocarbamate with transition metal ions. However, there are not enough such ions in the...

Leveraging disulfiram to treat cancer: Mechanisms of action, delivery strategies, and treatment regimens

Disulfiram (DSF) has been used as an alcoholism drug for 70 years. Recently, it has attracted increasing attention owing to the distinguished anticancer activity, which can be further potentiated by the supplementation of Cu²⁺. Although encouraging anticancer results are obtained in lab, the clinical outcomes of oral DSF are not satisfactory, which urges an in-depth understanding of the underlying mechanisms, bottlenecks, and proposal of potential methods to address the dilemma. In this review, a critical summarization of various molecular biological anticancer mechanisms of DSF/Cu²⁺ is provided and the predicament of orally delivering DSF in clinical oncotherapy is explained by the metabolic barriers. We highlight the recent advances in the DSF/Cu²⁺ delivery strategies and the emerging treatment regimens for cancer treatment. Last but not the least, we summarize the clinical trials regarding DSF and make a prospect of DSF/Cu-based cancer therapy.

Two-step fabricating micelle-like nanoparticles of cisplatin with the 'real' long circulation and high bioavailability for cancer therapy

Cisplatin is a widely used anticancer drug for various solid tumors. However, the serious adverse effects caused by systemic distribution limit its wide use. In this study, we intend to use biocompatible materials polyethyleneimine (PEI) and poly(L-glutamic acid)-g-methoxy poly(ethylene glycol) (PLG-g-PEG) to construct nanoparticles to enhance the efficacy of cisplatin and reduce its side effects. The micelle-like nanoparticles were fabricated by a simple two-step method, with a core consisting of PEI and cisplatin and a PLG-g-mPEG coating layer. The obtained nanoparticles have a small particle size (41.79 nm) and high drug loading (16.43%). The coated nanoparticles (NP-II) strengthened the structure of PEI and cisplatin complex (NP-I) and slowed the drug release for less than 20% at pH 7.4 PBS in 24 h. Therefore, it could effectively inhibit the binding of free drug and plasma proteins to achieve the long circulation, and the bioavailability could be increased to about 600% and 285% of cisplatin solution and NP-I respectively. Besides, the cellular uptake of NP-II was enhanced in the acidic tumor microenvironment due to the detachment of coating layer and the increase of positive zeta potential of nanoparticles, which was benefit to reduce the side effect of cisplatin to normal cells. In vivo pharmacodynamic experiments also showed that NP-II improved the efficacy and reduced side effects compared to the cisplatin solution. In conclusion, the two-step fabricating micelle-like nanoparticles with the improved therapeutic efficiency and reduced side effects show great potential for cancer chemotherapy.

Biodegradable Nanocatalyst with Self-Supplying Fenton-like Ions and H2O2 for Catalytic Cascade-Amplified Tumor Therapy

Therapeutic nanosystems triggered by a specific tumor microenvironment (TME) offer excellent safety and selectivity in the treatment of cancer by in situ conversion of a less toxic substance into effective anticarcinogens. However, the inherent antioxidant systems, hypoxic environment, and insufficient hydrogen peroxide (H₂O₂) in tumor cells severely limit their efficacy. Herein, a new strategy has been developed by loading the chemotherapy prodrug disulfiram (DSF) and coating glucose oxidase (GOD) on the surface of Cu/ZIF-8 nanospheres and finally encapsulating manganese dioxide (MnO₂) nanoshells to achieve efficient DSF-based cancer chemotherapy and dual-enhanced chemodynamic therapy (CDT). In an acidic TME, the nanocatalyst can biodegrade rapidly and accelerate the release of internal active substances. The outer layer of MnO₂ depletes glutathione (GSH) to destroy the reactive oxygen defensive mechanisms and achieves continuous oxygen generation, thus enhancing the catalytic efficiency of GOD to burst H₂O₂. Benefiting from the chelation reaction between the released Cu²⁺ and DSF, a large amount of cytotoxic CuET products is generated, and the Cu⁺ are concurrently released, thereby achieving efficient chemotherapy and satisfactory CDT efficacy. Furthermore, the release of Mn²⁺ can initiate magnetic resonance imaging signals for the tracking of the nanocatalyst.

Matrix Metalloproteinase-9-Responsive Surface Charge-Reversible Nanocarrier to Enhance Endocytosis as Efficient Targeted Delivery System for Cancer Diagnosis and Therapy

Nanoparticles, that can be enriched in the tumor microenvironment and deliver the payloads into cancer cells, are desirable carriers for theranostic agents in cancer diagnosis and treatment. However, efficient targeted delivery and enhanced endocytosis for probes and drugs in theranostics are still major challenges. Here, a nanoparticle, which is capable of charge reversal from negative to positive in response to matrix metalloproteinase 9 (MMP9) in tumor microenvironment is reported. This nanoparticle is based on a novel charge reversible amphiphilic molecule consisting of hydrophobic oleic acid, MMP9-cleavable peptide, and glutamate-rich segment (named as OMPE). The OMPE-modified cationic liposome forms an intelligent anionic nanohybrid (O-NP) with enhanced endocytosis through surface charge reversal in response to MMP9 in vitro. Successfully, O-NP nanohybrid performs preferential accumulation and enhances the endocytosis in MMP9-expressing xenografted tumors in mouse models, which improve the sensitivity of diagnosis agents and the antitumor effects of drugs in vivo by overcoming their low solubility and/or nonspecific enrichment. These results indicate that O-NP can be a promising delivery platform for cancer diagnosis and therapy.

Strategies and challenges to improve the performance of tumor-associated active targeting

Over the past decade, nanoparticle-based drug delivery systems have been extensively explored. However, the average tumour enrichment ratio of passive targeting systems corresponds to only 0.7% due to the nonspecific uptake by normal organs and poor selective retention in tumours. The therapeutic specificity and efficacy of nano-medicine can be enhanced by equipping it with active targeting ligands, although it is not possible to ignore the recognition and clearance of the reticuloendothelial system (RES) caused by targeting ligands. Given the complexity of the systemic circulation environment, it is necessary to carefully consider the hydrophobicity, immunogenicity, and electrical property of targeting ligands. Thus, for an active targeting system, the targeting ligands should be shielded in blood circulation and de-shielded in the tumour region for enhanced tumour accumulation. In this study, strategies for improving the performance of active targeting ligands are introduced. The strategies include irreversible shielding, reversible shielding, and methods of modulating the multivalent interactions between ligands and receptors. Furthermore, challenges and future developments in designing active ligand targeting systems are also discussed.

Nanomedicine Enables Drug-Potency Activation with Tumor Sensitivity and Hyperthermia Synergy in the Second Near-Infrared Biowindow

Disulfiram (DSF), a U.S. Food and Drug Administration (FDA)-approved drug for the treatment of chronic alcoholism, is also used as an antitumor drug in combination with Cu²⁺ ions. However, studies have shown that the endogenous Cu²⁺ dose in tumor tissues is still insufficient to form relatively high levels of a bis(N,N-diethyldithiocarbamate) copper(II) complex (denoted as Cu(DTC)₂) to selectively eradicate cancer cells. Here, DSF-loaded hollow copper sulfide nanoparticles (DSF@PEG-HCuSNPs) were designed to achieve tumor microenvironment (TME)-activated in situ formation of cytotoxic Cu(DTC)₂ for NIR-II-induced, photonic hyperthermia-enhanced, and DSF-initiated cancer chemotherapy. The acidic TME triggered the gradual degradation of DSF@PEG-HCuSNPs, promoting the rapid release of DSF and Cu²⁺ ions, causing the in situ formation of cytotoxic Cu(DTC)₂, to achieve efficient DSF-based chemotherapy. Additionally, DSF@PEG-HCuSNPs exhibited a notably high photothermal conversion efficiency of 23.8% at the second near-infrared (NIR-II) biowindow, thus significantly inducing photonic hyperthermia to eliminate cancer cells. Both in vitro and in vivo studies confirmed the effective photonic hyperthermia-induced chemotherapeutic efficacy of DSF by integrating the in situ formation of toxic Cu(DTC)₂ complexes and evident temperature elevation upon NIR-II laser irradiation. Thus, this study represents a distinctive paradigm of in situ Cu²⁺ chelation-initiated "nontoxicity-to-toxicity" transformation for photonic hyperthermia-augmented DSF-based cancer chemotherapy.

Thermosensitive Chitosan-Based Injectable Hydrogel as an Efficient Anticancer Drug Carrier

A thermosensitive, physically cross-linked injectable hydrogel was formulated for the effective and sustained delivery of disulfiram (DSF) to the cancer cells as there is no hydrogel formulation available until now for the delivery of DSF. As we know, hydrogels have an advantage over other drug delivery systems because of their unique properties, so we proposed to formulate an injectable hydrogel system for the sustained delivery of an anticancer drug (DSF) to cancer cells. To investigate the surface morphology, a scanning electron microscope study was carried out, and for thermal stability of hydrogels, TGA (thermogravimetric analysis) and DSC (differential scanning calorimetry) were performed. The rheological behavior of hydrogels was evaluated with the increasing temperature and time. These developed hydrogels possessing excellent biocompatibility could be injected at room temperature following rapid gel formation at body temperature. The swelling index and in vitro drug release studies were performed at different pH (6.8 and 7.4) and temperatures (25 and 37 °C). The cell viability of the blank hydrogel, free DSF solution, and Ch/DSF (chitosan/DSF)-loaded hydrogel was studied by MTT assay on SMMC-7721 cells for 24 and 48 h, which exhibited higher cytotoxicity in a dose-dependent manner in contrast to the free DSF solution. Moreover, the cellular uptake of DSF-loaded hydrogels was observed stronger as compared with free DSF. Hence, chitosan-based hydrogels loaded with DSF possessing exceptional properties can be used as a novel injectable anticancer drug for the sustained delivery of DSF for long-term cancer therapy.

Ultra-small-size Astragaloside-IV loaded lipid nanocapsules eye drops for the effective management of dry age-related macular degeneration

Background Age-related macular degeneration (AMD) is a major cause of severe visual loss in elderly people. The treatments for dry AMD (dAMD) are severely limited so far. In this work, we aim to develop an eye drop to protect retinal functions against oxidative stress and apoptosis for improving dAMD management. Methods Astragaloside-IV (ASIV) was prepared into phospholipid complex and loaded into three sizes (20, 50 and 90 nm) of ASIV lipid nanocapsules (ASIV-LNCs). The penetration and distribution of LNCs were investigated. DAMD mice model was induced by NaIO₃, and therapeutic effect was evaluated by electroretinography (ERG), histological examination, apoptosis and ROS detection. Results The ocular penetration and pharmacokinetic studies corroborated the feasibility of the LNCs to reach the fundus, and ultra-small-size LNCs (ASIV-LNCs-20) had the best delivery effect. ASIV-LNCs-20 was able to decrease ROS production and reduce the apoptosis rate from 5.12% to 0.533%. ERG and H&E staining results confirmed ASIV-LNCs-20 had a good protective effect on the morphology and function of the retina. Conclusions These results suggest that ASIV-LNCs can be a promising therapy approach for dAMD, and this research also offers new possibilities for further applications of LNCs as a drug delivery system for other eye diseases. Abbreviations AMD: Age-related macular degeneration;AREDS Age-related eye disease study; ASIV: Astragaloside-IV;AUC: Area under the concentration-time curve; dAMD: Dry age-related macular degeneration; DHE: Dihydroethidium; DL: Drug Loading; DLS: Dynamic light scattering; DSC: Differential scanning calorimetry; EE: Entrapment efficiency; ELSD: Evaporative light scattering detector; ERG: Electroretinographic; H&E: Hematoxylin and Eosin; I.S.: Internal standard; LB: Langmuir-Blodgett; LNCs: Lipid nanocapsules; MCT: Medium-chain triacylglycerol; ONL: Outer nuclear layer; OPL: Outer plexiform layer; PDI: Polydispersity index; PR: Photoreceptor;ROS: Reactive oxygen species; RPE: Retinal pigment epithelium; TEM: Transmission electron microscope; wAMD: Wet age-related macular degeneration.

N-Oxide polymer-cupric ion nanogels potentiate disulfiram for cancer therapy

Disulfiram (DSF) exerts potent anticancer activity via the formation of chelates with copper or zinc ions in tumor tissues, but the low abundance of these ions in the tumor cannot sustain its antitumor activity. Herein, we show that a zwitterionic water-soluble N-oxide polymer, poly[2-(N-oxide-N,N-dimethylamino)ethyl methacrylate] (OPDMA), can complex cupric ions and form nanogels (OPDMA/Cu), which efficiently deliver copper ions to tumor tissue to potentiate DSF significantly for effective antitumor therapy.

Amino acid transporters: Emerging roles in drug delivery for tumor-targeting therapy

Amino acid transporters, which play a vital role in transporting amino acids for the biosynthesis of mammalian cells, are highly expressed in types of tumors. Increasing studies have shown the feasibility of amino acid transporters as a component of tumor-targeting therapy. In this review, we focus on tumor-related amino acid transporters and their potential use in tumor-targeting therapy. Firstly, the expression characteristics of amino acid transporters in cancer and their relationship with tumor growth are reviewed. Secondly, the recognition requirements are discussed, focusing on the "acid-base" properties, conformational isomerism and structural analogues. Finally, recent developments in amino acid transporter-targeting drug delivery strategies are highlighted, including prodrugs and nanocarriers, with special attention to the latest findings of molecular mechanisms and targeting efficiency of transporter-mediated endocytosis. We aim to offer related clues that might lead to valuable tumor-targeting strategies by the utilization of amino acid transporters.

Doxorubicin intercalated copper diethyldithiocarbamate functionalized layered double hydroxide hybrid nanoparticles for targeted therapy of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the deadliest cancers due to its long incubation period and low cure rate. Layered double hydroxide (LDH) nanoparticles have attracted considerable research interest in the field of nanomedicine owing to their surface effects and good biocompatibility. In this research, we synthesized a hexagonal nanoparticle by the co-precipitation method, referred to as Cu-Al LDH. As an alternative to traditional drug-loading methods, sodium diethyldithiocarbamate (DDC) was introduced and combined with Cu²⁺ in LDHs to form a diethyldithiocarbamate-copper complex (Cu(DDC)₂), which was not only the composition of carrier materials but also an effective component for cancer therapy. Doxorubicin (DOX) was also encapsulated into LDHs due to the clinical relevance of DOX treatment for HCC. Formulations of the Cu(DDC)₂ and DOX co-loaded nanoparticles were optimized to precisely control the Cu(DDC)₂/DOX ratio. The nanoparticles were coated with polyethylene glycol-graft-polyglutamic acid (PEG-PLG) through electrostatic adsorption to improve the stability of the nanoparticles. The outer layer was decorated with hyaluronic acid (HA) to achieve specific targeting of tumors. Compared with non-HA coated nanoparticles, HA coated nanoparticles showed greater cellular uptake in Hep G2 cells, which could cause higher cytotoxicity. In addition, targeted nanoparticles effectively inhibited tumor growth in mouse models of ectopic hepatocellular carcinoma. It can be concluded that there is a great potential for synergistic cancer therapy using the novel DOX intercalated Cu(DDC)₂ functionalized layered double hydroxide hybrid nanoparticles.

Old wine in new bottles: Advanced drug delivery systems for disulfiram-based cancer therapy

Disulfiram (DSF) is an FDA-approved drug that has been repurposed for cancer treatment. It showed excellent anticancer efficacy in combination with copper ions (Cu). Several active clinical trials testing the anticancer efficacy of DSF against various cancers are underway. In this review article, we summarized different delivery strategies for DSF-based cancer therapy. In many studies, DSF and Cu were delivered in two separate formulations. DSF and Cu formed copper diethyldithiocarbamate [Cu(DDC)₂] complex which was reported as a major active anticancer ingredient for DSF/Cu combination therapy. Various delivery systems for DSF and Cu were developed to enhance their delivery into tumors. The administration of preformed Cu(DDC)₂ complex was also explored to achieve better anticancer efficacy. Several studies developed formulations that were capable of delivering Cu(DDC)₂ complex in a single formulation. These novel formulations will address drug delivery challenges and have great potential to improve the efficacy of DSF-based cancer therapy. DSF is an off-patent drug molecule. The novel drug formulations of DSF will also serve as a good strategy for developing intellectual properties which will be critical for product development and commercialization.

Recent advances in the delivery of disulfiram: a critical analysis of promising approaches to improve its pharmacokinetic profile and anticancer efficacy

BACKGROUND

Disulfiram (DSF) has a long history of being used as a first-line promising therapy for treatment of alcoholism in human. Besides its prominence in the treatment of alcoholism, extensive investigations have been carried out to explore other biomedical and pharmacological effects of DSF. Amongst other biomedical implications, plenty researches have shown evidence of promising anticancer efficacy of this agent for treatment of wide range of cancers such as breast cancer, liver cancer and lung carcinoma.

METHODS

Electronic databases, including Google scholar, PubMed and Web of science were searched with the keywords disulfiram, nanoparticles, cancer, drug delivery systems.

RESULT

Despite its excellent anticancer efficacy, the pharmaceutical significance and clinical applicability of DSF are hampered due to poor stability, low solubility, short plasma half-life, rapid metabolism, and early clearance from systemic circulation. Various attempts have been made to eradicate these issues. Nanotechnology based interventions have gained remarkable recognition in improving pharmacokinetic and pharmacodynamic profile of DSF by improving its stability and avoiding its degradation.

CONCLUSION

The aim of the present review is to critically analyse all recent developments in designing various nanotechnology-based delivery systems, to ponder their relevance in improving stability, pharmacokinetic and pharmacodynamic profile, and achieving target-specific delivery of this agent to cancer cells to effectively eradicate cancer and abolish its metastasis. Nanotechnology is a novel approach for overcoming such obstacles faced presently, the results obtained so far using different novel drug delivery systems seem to be very promising to increase the stability and half-life of DSF. Graphical abstract Nanocrrier mediated drug delivery systems for disulfiram.

Magnetic Reactive Oxygen Species Nanoreactor for Switchable Magnetic Resonance Imaging Guided Cancer Therapy Based on pH-Sensitive Fe5C2@Fe3O4 Nanoparticles

Reactive oxygen species (ROS) are crucial molecules in cancer therapy. Unfortunately, the therapeutic efficiency of ROS is unsatisfactory in clinic, primarily due to their rigorous production conditions. By taking advantage of the intrinsic acidity and overproduction of H₂O₂ in the tumor environment, we have reported an ROS nanoreactor based on core-shell-structured iron carbide (Fe₅C₂@Fe₃O₄) nanoparticles (NPs) through the catalysis of the Fenton reaction. These NPs are able to release ferrous ions in acidic environments to disproportionate H₂O₂ into ^•OH radicals, which effectively inhibits the proliferation of tumor cells both in vitro and in vivo. The high magnetization of Fe₅C₂@Fe₃O₄ NPs is favorable for both magnetic targeting and T₂-weighted magnetic resonance imaging (MRI). Ionization of these NPs simultaneously decreases the T₂ signal and enhances the T₁ signal in MRI, and this T₂/T₁ switching process provides the visualization of ferrous ions release and ROS generation for the supervision of tumor curing. These Fe₅C₂@Fe₃O₄ NPs show great potential in endogenous environment-excited cancer therapy with high efficiency and tumor specificity and can be guided further by MRI.

A dithiocarbamate-based H2O2-responsive prodrug for combinational chemotherapy and oxidative stress amplification therapy

A H₂O₂-responsive dithiocarbamate-based prodrug was designed for combinational cancer therapy, showing superior anticancer efficacy and biostability to disulfiram.

Synergistic breast tumor cell killing achieved by intracellular co-delivery of doxorubicin and disulfiram via core-shell-corona nanoparticles

Combination therapy with different functional chemotherapeutic agents based on nano-drug delivery systems is an effective strategy for the treatment of breast cancer. However, co-delivery of drug molecules with different physicochemical properties still remains a challenge. In this study, an amphiphilic poly (ε-caprolactone)-b-poly (l-glutamic acid)-g-methoxy poly (ethylene glycol) (PCL-b-PGlu-g-mPEG) copolymer was designed and synthesized to develop a nanocarrier for the co-delivery of hydrophilic doxorubicin (DOX) and hydrophobic disulfiram (DSF). The amphiphilic copolymer self-assembled into core-shell-corona structured nanoparticles with the hydrophobic PCL core for DSF loading (hydrophobic interaction) and anionic poly (glutamic acid) shell for DOX loading (electrostatic interaction). DSF and DOX co-loaded nanoparticles (Co-NPs) resulted in high drug loading and precisely controlled DSF/DOX ratio via formulation optimization. Compared with free drug solutions, DSF and DOX delivered by the Co-NPs were found to have improved intracellular accumulation. Results of cytotoxicity assays showed that DSF/DOX delivered at the weight ratio of 0.5 and 1 could achieve a synergistic cytotoxic effect on breast cancer cell lines (MCF-7 and MDA-MB-231). In vivo imaging confirmed that the core-shell-corona nanoparticles could efficiently accumulate in tumors. In vivo anti-tumor effect results indicated that Co-NPs showed an improved drug synergistic effect on antitumor activity compared with the free drug combination. Therefore, it can be concluded that core-shell-corona nanoparticles prepared by PCL-b-PGlu-g-mPEG could be a promising co-delivery system for drug combination therapy in the treatment of breast cancer.

Pure paclitaxel nanoparticles: preparation, characterization, and antitumor effect for human liver cancer SMMC-7721 cells

Introduction

Pure paclitaxel nanoparticles (PPN), consisting entirely of drug molecules, were prepared by the electrostatic spraying method as promising candidates for antitumor application. Compared with the traditional preparation method, the advantage of the electrostatic spraying method included high production rates, relatively small particle sizes, and ease of preparation.

Materials and methods

Paclitaxel was used to prepared PPN by electrostatic spray. The electrostatic spray device included a constant speed pump with a syringe, a high-voltage power supply, and a metal foil receiver was used to prepare and evaluate PPN. The syringe drew off a certain amount of paclitaxel chloroform solution (150 μg/mL) and was placed on the constant speed injection pump. The dissolution behavior of PPN was evaluated by dissolution test and the presence of paclitaxel in PPN was detected by X-Ray powder diffraction and differential scanning calorimetry. Effect of PPN on SMMC-7721 cells were studied by cell uptake, cell apoptosis and antitumor study.

Results

The results of X-ray powder diffraction and differential scanning calorimetry characterization showed that the PPN were in an amorphous state. A dissolution study indicated that PPN have a significantly enhanced dissolution rate of paclitaxel. Moreover, SMMC-7721 tumor cells treated with PPN exhibited a distinctly high uptake rate that promoted cell apoptosis. An in vivo antitumor study demonstrated that PPN had significant antitumor efficacy.

Conclusion

All conclusions verified that electrostatic spraying is a potential technology for developing PPN, and PPN can be regarded as a promising treatment for cancer.

Redox-Dependent Copper Carrier Promotes Cellular Copper Uptake and Oxidative Stress-Mediated Apoptosis of Cancer Cells

Transportation of exogenous copper ions into cancer cells by copper carriers has gained increasing interest for cancer chemotherapy. We disclosed herein a redox-dependent copper carrier, 2,2'-dithiodipyridine (DPy), which binds copper ions and carries the cargo into cells. The cellular reducing environment cleaved the disulfide bond in DPy to facilitate unloading copper ions. The elevated copper level then elicits oxidative stress and subsequently promotes the reformation of DPy. Further mechanistic studies revealed that the DPy/copper combination predominantly targets the cellular redox-regulating systems, including the thioredoxin system and the glutathione system, to induce the oxidative stress-mediated death of tumor cells. The discovery of DPy as a cleavable and recyclable copper shuttle provides a proof of concept for designing novel biomaterials for copper transportation as potential anticancer agents.

Investigation of the key chemical structures involved in the anticancer activity of disulfiram in A549 non-small cell lung cancer cell line

Background

Disulfiram (DS), an antialcoholism medicine, demonstrated strong anticancer activity in the laboratory but did not show promising results in clinical trials. The anticancer activity of DS is copper dependent. The reaction of DS and copper generates reactive oxygen species (ROS). After oral administration in the clinic, DS is enriched and quickly metabolised in the liver. The associated change of chemical structure may make the metabolites of DS lose its copper-chelating ability and disable their anticancer activity. The anticancer chemical structure of DS is still largely unknown. Elucidation of the relationship between the key chemical structure of DS and its anticancer activity will enable us to modify DS and speed its translation into cancer therapeutics.

Methods

The cytotoxicity, extracellular ROS activity, apoptotic effect of DS, DDC and their analogues on cancer cells and cancer stem cells were examined in vitro by MTT assay, western blot, extracellular ROS assay and sphere-reforming assay.

Results

Intact thiol groups are essential for the in vitro cytotoxicity of DS. S-methylated diethyldithiocarbamate (S-Me-DDC), one of the major metabolites of DS in liver, completely lost its in vitro anticancer activity. In vitro cytotoxicity of DS was also abolished when its thiuram structure was destroyed. In contrast, modification of the ethyl groups in DS had no significant influence on its anticancer activity.

Conclusions

The thiol groups and thiuram structure are indispensable for the anticancer activity of DS. The liver enrichment and metabolism may be the major obstruction for application of DS in cancer treatment. A delivery system to protect the thiol groups and development of novel soluble copper-DDC compound may pave the path for translation of DS into cancer therapeutics.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4617-x) contains supplementary material, which is available to authorized users.

Disulfiram-loaded mixed nanoparticles with high drug-loading and plasma stability by reducing the core crystallinity for intravenous delivery

To develop an injectable formulation and improve the stability of disulfiram (DSF), DSF was encapsulated into mixed nanoparticles (DSF-NPs) through a high-pressure homogenization method. The Flory-Huggins interaction parameters (χ_FH) were calculated to predict the miscibility between DSF and the hydrophobic core, resulting in PCL₅₀₀₀ selected as the hydrophobic block to encapsulate the DSF, as PCL₅₀₀₀ had a lower χ_FH 3.39 and the drug loading of the nanoparticles prepared by mPEG₅₀₀₀-PCL₅₀₀₀ was relatively higher. mPEG₅₀₀₀-PCL₅₀₀₀ and PCL₅₀₀₀ were blended to reduce the leakage of DSF during preparation, as well as increase the stability of the nanoparticles. The cargo-loading capacity of the nanoparticles was improved from 3.35% to 5.50% by reducing the crystallinity of the PCL nanoparticle core, and the crystallinity decreased from 51.13% to 25.15% after adding medium chain triglyceride (MCT). The DSF-NPs prepared by the above method had a small particle size of 98.1 ± 10.54 nm, with a polydispersity index (PDI) of 0.036, as well as drug loading of 5.50%. Furthermore, DSF-NPs containing MCT showed higher stability than DSF-NPs without MCT and DSF-sol (DSF dissolved in Cremophor EL and ethanol) in water and 90% plasma-containing PBS. The pharmacokinetics proved that DSF-NPs containing MCT enhanced the DSF concentration in the blood. Finally, DSF-NPs effectively inhibited H22 xenograft tumor growth in vivo.

Repurposing disulfiram for cancer therapy via targeted nanotechnology through enhanced tumor mass penetration and disassembly

Disulfiram (DSF), an FDA approved drug for the treatment of alcoholism, degrades to therapeutically active diethyldithiocarbamate (DDTC) in the body by reduction. Hereby, we developed a redox sensitive DDTC-polymer conjugate for targeted cancer therapy. It was found that the DDTC-polymer conjugate modified with a β-d-galactose receptor targeting ligand can self-assemble into LDNP nanoparticle and efficiently enter cancer cells by receptor-mediated endocytosis. Upon cellular uptake, the LDNP nanoparticle degrades and releases DDTC due to the cleavage of disulfide bonds, and subsequently forms copper (II) DDTC complex to kill a broad spectrum of cancer cells. 3D cell culture revealed that this nanoparticle shows much stronger tumor mass penetrating and destructive capacity. Furthermore, LDNP nanoparticles exhibited much greater potency in inhibiting tumor growth in a peritoneal metastatic ovarian tumor model.

STATEMENT OF SIGNIFICANCE

The β-d-galactose receptor targeted disulfiram loaded nanoparticle (LDNP) is novel in the following aspects.

Anti-hepatocellular carcinoma properties of the anti-alcoholism drug disulfiram discovered to enzymatically inhibit the AMPK-related kinase SNARK in vitro

We recently described that the anti-apoptotic AMPK-related kinase, SNARK, promotes transforming growth factor (TGF)-β signaling in hepatocellular carcinoma (HCC) cells, as a potentially new therapeutic target. Here we explored FDA-approved drugs inhibiting the enzymatic activity of SNARK, using an in vitro luminescence kinase assay system. Interestingly, the long-used anti-alcoholism drug disulfiram (DSF), also known as Antabuse, emerged as the top hit. Enzymatic kinetics analyses revealed that DSF inhibited SNARK kinase activity in a noncompetitive manner to ATP or phosphosubstrates. Comparative in vitro analyses of DSF analogs indicated the significance of the disulfide bond-based molecular integrity for the kinase inhibition. DSF suppressed SNARK-promoted TGF-β signaling and demonstrated anti-HCC effects. The chemical and enzymatic findings herein reveal novel pharmacological effects of and use for DSF and its derivatives, and could be conducive to prevention and inhibition of liver fibrosis and HCC.

Brain- and brain tumor-penetrating disulfiram nanoparticles: Sequence of cytotoxic events and efficacy in human glioma cell lines and intracranial xenografts

There is great interest in repurposing disulfiram (DSF), a rapidly metabolizing nontoxic drug, for brain cancers and other cancers. To overcome the instability and low therapeutic efficacy, we engineered passively-targeted DSF-nanoparticles (DSFNPs) using biodegradable monomethoxy (polyethylene glycol) d,l-lactic-co-glycolic acid (mPEG-PLGA) matrix. The physicochemical properties, cellular uptake and the blood brain-barrier permeability of DSFNPs were investigated. The DSFNPs were highly stable with a size of ∼70 nm with a >90% entrapment. Injection of the nanoparticles labeled with HITC, a near-infrared dye into normal mice and tumor-bearing nude mice followed by in vivo imaging showed a selective accumulation of the formulation within the brain and subcutaneous tumors for >24 h, indicating an increased plasma half-life and entry of DSF into desired sites. The DSFNPs induced a potent and preferential killing of many brain tumor cell lines in cytotoxicity assays. Confocal microscopy showed a quick internalization of the nanoparticles in tumor cells followed by initial accumulation in lysosomes and subsequently in mitochondria. DSFNPs induced high levels of ROS and led to a marked loss of mitochondrial membrane potential. Activation of the MAP-kinase pathway leading to a nuclear translocation of apoptosis-inducing factor and altered expression of apoptotic and anti-apoptotic proteins were also observed. DSFNPs induced a powerful and significant regression of intracranial medulloblastoma xenografts compared to the marginal efficacy of unencapsulated DSF. Together, we show that passively targeted DSFNPs can affect multiple targets, trigger potent anticancer effects, and can offer a sustained drug supply for brain cancer treatment through an enhanced permeability retention (EPR).

Disulfiram combined with copper inhibits metastasis and epithelial-mesenchymal transition in hepatocellular carcinoma through the NF-κB and TGF-β pathways

Late‐stage hepatocellular carcinoma (HCC) usually has a low survival rate because of the high risk of metastases and the lack of an effective cure. Disulfiram (DSF) has copper (Cu)‐dependent anticancer properties in vitro and in vivo. The present work aims to explore the anti‐metastasis effects and molecular mechanisms of DSF/Cu on HCC cells both in vitro and in vivo. The results showed that DSF inhibited the proliferation, migration and invasion of HCC cells. Cu improved the anti‐metastatic activity of DSF, while Cu alone had no effect. Furthermore, DSF/Cu inhibited both NF‐κB and TGF‐β signalling, including the nuclear translocation of NF‐κB subunits and the expression of Smad4, leading to down‐regulation of Snail and Slug, which contributed to phenotype epithelial–mesenchymal transition (EMT). Finally, DSF/Cu inhibited the lung metastasis of Hep3B cells not only in a subcutaneous tumour model but also in an orthotopic liver metastasis assay. These results indicated that DSF/Cu suppressed the metastasis and EMT of hepatic carcinoma through NF‐κB and TGF‐β signalling. Our study indicates the potential of DSF/Cu for therapeutic use.

Improved tumor tissue penetration and tumor cell uptake achieved by delayed charge reversal nanoparticles

The high affinity of positively charged nanoparticles to biological interfaces makes them easily taken up by tumor cells but limits their tumor permeation due to non-specific electrostatic interactions. In this study, polyion complex coated nanoparticles with different charge reversal profiles were developed to study the influence of charge reversal profile on tumor penetration. The system was constructed by polyion complex coating using micelles composed of poly (lysine)-b-polycaprolactone (PLys-b-PCL) as the cationic core and poly (glutamic acid)-g- methoxyl poly (ethylene glycol) (PGlu-g-mPEG) as the anionic coating material. Manipulation of charge reversal profile was achieved by controlling the polymer chain entanglement and electrostatic interaction in the polyion complex layer through glutaraldehyde-induced shell-crosslinking. The delayed charge reversal nanoparticles (CTCL30) could maintain negatively charged in pH 6.5 PBS for at least 2h and exhibit pH-responsive cytotoxicity and cellular uptake in an extended time scale. Compared with a faster charge reversal counterpart (CTCL70) with similar pharmacokinetic profile, CTCL30 showed deeper penetration, higher in vivo tumor cell uptake and stronger antitumor activity in vivo (tumor inhibition rate: 72.3% vs 60.2%, compared with CTCL70). These results indicate that the delayed charge reversal strategy could improve therapeutic effect via facilitating tumor penetration.

STATEMENT OF SIGNIFICANCE

Here, the high tumor penetration capability of PEG-coated nanoparticles and the high cellular uptake of cationic nanoparticles were combined by a delayed charge reversal drug delivery system. This drug delivery system was composed of a drug-loading cationic inner core and a polyion complex coating. Manipulation of charge reversal profile was realized by varying the crosslinking degree of the shell of the cationic inner core, through which changed the strength of the polyion complex layer. Nanoparticles with delayed charge reversal profile exhibited improved tumor penetration, in vivo tumor cell uptake and in vivo tumor growth inhibition effect although they have similar pharmacokinetic and biodistribution behaviors with their instant charge reversal counterpart.