Redox-Activatable ATP-Depleting Micelles with Dual Modulation Characteristics for Multidrug-Resistant Cancer Therapy

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.

Intelligent Size-Switchable Iron Carbide-Based Nanocapsules with Cascade Delivery Capacity for Hyperthermia-Enhanced Deep Tumor Ferroptosis

The ferroptosis pathway is recognized as an essential strategy for tumor treatment. However, killing tumor cells in deep tumor regions with ferroptosis agents is still challenging because of distinct size requirements for intratumoral accumulation and deep tumor penetration. Herein, intelligent nanocapsules with size-switchable capability that responds to acid/hyperthermia stimulation to achieve deep tumor ferroptosis are developed. These nanocapsules are constructed using poly(lactic-co-glycolic) acid and Pluronic F127 as carrier materials, with Au-Fe2 C Janus nanoparticles serving as photothermal and ferroptosis agents, and sorafenib (SRF) as the ferroptosis enhancer. The PFP@Au-Fe2 C-SRF nanocapsules, designed with an appropriate size, exhibit superior intratumoral accumulation compared to free Au-Fe2 C nanoparticles, as evidenced by photoacoustic and magnetic resonance imaging. These nanocapsules can degrade within the acidic tumor microenvironment when subjected to laser irradiation, releasing free Au-Fe2 C nanoparticles. This enables them to penetrate deep into tumor regions and disrupt intracellular redox balance. Under the guidance of imaging, these PFP@Au-Fe2 C-SRF nanocapsules effectively inhibit tumor growth when exposed to laser irradiation, capitalizing on the synergistic photothermal and ferroptosis effects. This study presents an intelligent formulation based on iron carbide for achieving deep tumor ferroptosis through size-switchable cascade delivery, thereby advancing the comprehension of ferroptosis in the context of tumor theranostics.

Nanodelivery systems: An efficient and target-specific approach for drug-resistant cancers

BACKGROUND

Cancer treatment is still a global health challenge. Nowadays, chemotherapy is widely applied for treating cancer and reducing its burden. However, its application might be in accordance with various adverse effects by exposing the healthy tissues and multidrug resistance (MDR), leading to disease relapse or metastasis. In addition, due to tumor heterogeneity and the varied pharmacokinetic features of prescribed drugs, combination therapy has only shown modestly improved results in MDR malignancies. Nanotechnology has been explored as a potential tool for cancer treatment, due to the efficiency of nanoparticles to function as a vehicle for drug delivery.

METHODS

With this viewpoint, functionalized nanosystems have been investigated as a potential strategy to overcome drug resistance.

RESULTS

This approach aims to improve the efficacy of anticancer medicines while decreasing their associated side effects through a range of mechanisms, such as bypassing drug efflux, controlling drug release, and disrupting metabolism. This review discusses the MDR mechanisms contributing to therapeutic failure, the most cutting-edge approaches used in nanomedicine to create and assess nanocarriers, and designed nanomedicine to counteract MDR with emphasis on recent developments, their potential, and limitations.

CONCLUSIONS

Studies have shown that nanoparticle-mediated drug delivery confers distinct benefits over traditional pharmaceuticals, including improved biocompatibility, stability, permeability, retention effect, and targeting capabilities.

DNA Aptamer Beacon Probe (ABP) for Monitoring of Adenosine Triphosphate Level in SW480 Cancer Cells Treated with Glycolysis Inhibitor 2-Deoxyglucose

Early cancer screening enables timely detection of carcinogenesis, and aids in prompt clinical intervention. Herein, we report on the development of a simple, sensitive, and rapid fluorometric assay based on the aptamer probe (aptamer beacon probe, ABP) for monitoring the energy-demand biomarker adenosine triphosphate (ATP), an essential energy source that is released into the tumor microenvironment. Its level plays a significant role in risk assessment of malignancies. The operation of the ABP for ATP was examined using solutions of ATP and other nucleotides (UTP, GTP, CTP), followed by monitoring of ATP production in SW480 cancer cells. Then, the effect of a glycolysis inhibitor, 2-deoxyglucose (2-DG), on SW480 cells was investigated. The stability of predominant ABP conformations in the temperature range of 23-91 °C and the effects of temperature on ABP interactions with ATP, UTP, GTP, and CTP were evaluated based on quenching efficiencies (QE) and Stern-Volmer constants (K_SV). The optimized temperature for best selectivity of ABP toward ATP was 40 °C (K_SV = 1093 M^-1, QE = 42%). We have found that the inhibition of glycolysis in SW480 cancer cells by 2-deoxyglucose resulted in lowering of ATP production by 31.7%. Therefore, monitoring and modulation of ATP concentration may aid in future cancer treatment.

CES1-Triggered Liver-Specific Cargo Release of CRISPR/Cas9 Elements by Cationic Triadic Copolymeric Nanoparticles Targeting Gene Editing of PCSK9 for Hyperlipidemia Amelioration

The broad application of clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 genome editing tools is hindered by challenges in the efficient delivery of its two components into specific cells and intracytoplasmic release. Herein, a novel copolymer for delivery of Cas9-mRNA/ single-guide RNA (Cas9-mRNA/sgRNA) in vitro and vivo, using carboxylesterase-responsive cationic triadic copolymeric nanoparticles targeted proprotein convertase subtilisin/kexin type 9 (PCSK9) for hyperlipidemia amelioration is reported. A dimethyl biguanide derivative is designed and synthesized to form cationic block, and copolymerization onto prepolymer with propyl methacrylate, to fabricate a triadic copolymer mPEG-b-P(Met/n-PMA). The copolymer can self-assemble with Cas9-mRNA/sgRNA, indicating the excellent potential of nanoparticles to form a delivery carrier. This vehicle can efficiently release RNA in response to the hepatocytes carboxylesterase for genome editing. It was demonstrated that the mPEG-b-P(Met/n-PMA)/Cas9 mRNA/sgRNA nanoparticles effectively accumulated in hepatocytes, lead to the inhibition of PCSK9, and lowered the levels of Low-density lipoprotein cholesterol and total cholesterol in mouse serum down 20% of nontreatment. Interestingly, the nanoparticles even enable multiple functions in the regulation of blood glucose and weight. This study establishes a novel method to achieve complex CRISPR components stable loading, safe delivery, and fixed-point release, which expand the application of CRISPR delivery systems.

Glutamine metabolism targeting liposomes for synergistic chemosensitization and starvation therapy in ovarian cancer

Platinum-based chemotherapy is a first-line therapeutic regimen against ovarian cancer (OC); however, the therapeutic potential is always reduced by glutamine metabolism. Herein, a valid strategy of inhibiting glutamine metabolism was proposed to cause tumor starvation and chemosensitization. Specifically, reactive oxygen species-responsive liposomes were developed to co-deliver cisplatin (CDDP) and bis-2-(5-phenylacetamido-1,3,4-thiadiazol-2-yl) ethyl sulfide (BPTES) [C@B LPs]. The C@B LPs induced effective tumor cell starvation and significantly sensitized OC cells to CDDP by reducing glutathione generation to prevent CDDP detoxification, suppressing ATP production to avoid CDDP efflux, hindering nucleotide synthesis to aggravate DNA damage induced by CDDP, and blocking mammalian target of rapamycin (mTOR) signaling to promote cell apoptosis. More importantly, C@B LPs remarkably inhibited tumor growth in vivo and reduced the side effects. Taken together, this study provided a successful strategy of synergistic chemosensitization and starvation therapy escalating the rate of therapeutic success in OCs. STATEMENT OF SIGNIFICANCE: This work proposed a valid strategy of inhibiting glutamine metabolism to cause tumor starvation and chemosensitization. Specifically, ROS-responsive liposomes were developed to co-deliver cisplatin CDDP and BPTES [C@B LPs]. The C@B LPs induced effective tumor cell starvation and significantly sensitized OC cells to cisplatin by reducing glutathione generation to prevent cisplatin detoxification, suppressing ATP production to avoid cisplatin efflux, hindering nucleotide synthesis to aggravate DNA damage induced by cisplatin, and blocking mTOR signaling to promote cell apoptosis. More importantly, C@B LPs remarkably inhibited tumor growth in vivo and reduced the side effects. Taken together, this study provided a successful strategy of synergistic chemosensitization and starvation therapy escalating the rate of therapeutic success in OCs.

Recent advances in nanotechnology approaches for non-viral gene therapy

Gene therapy has shown great potential in the treatment of many diseases by downregulating the expression of certain genes. The development of gene vectors as a vehicle for gene therapy has greatly facilitated the widespread clinical application of nucleic acid materials (DNA, mRNA, siRNA, and miRNA). Currently, both viral and non-viral vectors are used as delivery systems of nucleic acid materials for gene therapy. However, viral vector-based gene therapy has several limitations, including immunogenicity and carcinogenesis caused by the exogenous viral vectors. To address these issues, non-viral nanocarrier-based gene therapy has been explored for superior performance with enhanced gene stability, high treatment efficiency, improved tumor-targeting, and better biocompatibility. In this review, we discuss various non-viral vector-mediated gene therapy approaches using multifunctional biodegradable or non-biodegradable nanocarriers, including polymer-based nanoparticles, lipid-based nanoparticles, carbon nanotubes, gold nanoparticles (AuNPs), quantum dots (QDs), silica nanoparticles, metal-based nanoparticles and two-dimensional nanocarriers. Various strategies to construct non-viral nanocarriers based on their delivery efficiency of targeted genes will be introduced. Subsequently, we discuss the cellular uptake pathways of non-viral nanocarriers. In addition, multifunctional gene therapy based on non-viral nanocarriers is summarized, in which the gene therapy can be combined with other treatments, such as photothermal therapy (PTT), photodynamic therapy (PDT), immunotherapy and chemotherapy. We also provide a comprehensive discussion of the biological toxicity and safety of non-viral vector-based gene therapy. Finally, the present limitations and challenges of non-viral nanocarriers for gene therapy in future clinical research are discussed, to promote wider clinical applications of non-viral vector-based gene therapy.

Nanomedicine Strategies for Management of Drug Resistance in Lung Cancer

Lung cancer (LC) is one of the leading causes of cancer occurrence and mortality worldwide. Treatment of patients with advanced and metastatic LC presents a significant challenge, as malignant cells use different mechanisms to resist chemotherapy. Drug resistance (DR) is a complex process that occurs due to a variety of genetic and acquired factors. Identifying the mechanisms underlying DR in LC patients and possible therapeutic alternatives for more efficient therapy is a central goal of LC research. Advances in nanotechnology resulted in the development of targeted and multifunctional nanoscale drug constructs. The possible modulation of the components of nanomedicine, their surface functionalization, and the encapsulation of various active therapeutics provide promising tools to bypass crucial biological barriers. These attributes enhance the delivery of multiple therapeutic agents directly to the tumor microenvironment (TME), resulting in reversal of LC resistance to anticancer treatment. This review provides a broad framework for understanding the different molecular mechanisms of DR in lung cancer, presents novel nanomedicine therapeutics aimed at improving the efficacy of treatment of various forms of resistant LC; outlines current challenges in using nanotechnology for reversing DR; and discusses the future directions for the clinical application of nanomedicine in the management of LC resistance.

Mitochondrial Ca2+-overloading by oxygen/glutathione depletion-boosted photodynamic therapy based on a CaCO3 nanoplatform for tumor synergistic therapy

The Ca²⁺ buffering capacity of mitochondria maintains the balance of cell physiological activities. The exogenous reactive oxygen species (ROS) can be used to break the balance, resulting in mitochondrial dysfunction and irreversible cell apoptosis. Herein, the CaCO₃-based tumor microenvironment (TME) responsive nanoplatform (CaNP_CAT+BSO@Ce6-PEG) was designed for oxygen/GSH depletion-boosted photodynamic therapy (PDT) and mitochondrial Ca²⁺-overloading synergistic therapy. In acidic TME, CaCO₃ decomposed and released the cargos (catalase (CAT), buthionine sulfoximine (BSO), chlorin e6 (Ce6), and Ca²⁺). The tumor hypoxia and reductive microenvironment could be significantly reversed by CAT and BSO, which greatly enhanced the PDT efficacy. The generated ¹O₂ during PDT process not only directly killed cancer cells but also destroyed the Ca²⁺ buffering capacity, leading to the mitochondrial Ca²⁺-overloading. The increased Ca²⁺ concentration promoted the process of oxidative phosphorylation and inhibited the production of adenosine triphosphate (ATP), resulting in the acceleration of cell death. Under the joint action of enhanced PDT and mitochondrial Ca²⁺-overloading, the CaNP_CAT+BSO@Ce6-PEG NPs showed remarkable synergistic effects in tumor inhibition without any side effects. STATEMENT OF SIGNIFICANCE: In the manuscript, a CaCO₃-based nano-platform for tumor microenvironment response was designed. With the decomposition of CaNP_CAT+BSO@Ce6-PEG NPs in the acidic tumor microenvironment, the released catalase (CAT) and buthionine sulfoximine (BSO) could relieve the tumor hypoxia and inhibit GSH production. Under 660 nm laser irradiation, the photodynamic effect was enhanced and caused apoptosis. Meanwhile, the Ca²⁺ buffering capacity was destroyed which led to the mitochondrial Ca²⁺-overloading. The synergistic effect of enhanced PDT and mitochondrial Ca²⁺-overloading made the CaNP_CAT+BSO@Ce6-PEG NPs present remarkable antitumor performance.

Polymeric Drug Delivery System Based on Pluronics for Cancer Treatment

Pluronic polymers (pluronics) are a unique class of synthetic triblock copolymers containing hydrophobic polypropylene oxide (PPO) and hydrophilic polyethylene oxide (PEO) arranged in the PEO-PPO-PEO manner. Due to their excellent biocompatibility and amphiphilic properties, pluronics are an ideal and promising biological material, which is widely used in drug delivery, disease diagnosis, and treatment, among other applications. Through self-assembly or in combination with other materials, pluronics can form nano carriers with different morphologies, representing a kind of multifunctional pharmaceutical excipients. In recent years, the utilization of pluronic-based multi-functional drug carriers in tumor treatment has become widespread, and various responsive drug carriers are designed according to the characteristics of the tumor microenvironment, resulting in major progress in tumor therapy. This review introduces the specific role of pluronic-based polymer drug delivery systems in tumor therapy, focusing on their physical and chemical properties as well as the design aspects of pluronic polymers. Finally, using newer literature reports, this review provides insights into the future potential and challenges posed by different pluronic-based polymer drug delivery systems in tumor therapy.

Pluronic Micelle-Mediated Tissue Factor Silencing Enhances Hemocompatibility, Stemness, Differentiation Potential, and Paracrine Signaling of Mesenchymal Stem Cells

Mesenchymal stem/stromal cells (MSCs) evoke great excitement for treating different human diseases due to their ability to home inflamed tissues, suppress inflammation, and promote tissue regeneration. Despite great promises, clinical trial results are disappointing as allotransplantation of MSCs trigger thrombotic activity and are damaged by the complement system, compromising their survival and function. To overcome this, a new strategy is presented by the silencing of tissue factor (TF), a transmembrane protein that mediates procoagulant activity. Novel Pluronic-based micelles are designed with the pendant pyridyl disulfide group, which are used to conjugate TF-targeting siRNA by the thiol-exchange reaction. This nanocarrier design effectively delivered the payload to MSCs resulting in ∼72% TF knockdown (KD) without significant cytotoxicity. Hematological evaluation of MSCs and TF-KD MSCs in an ex vivo human whole blood model revealed a significant reduction in an instant-blood-mediated-inflammatory reaction as evidenced by reduced platelet aggregation (93% of free platelets in the TF-KD group, compared to 22% in untreated bone marrow-derived MSCs) and thrombin–antithrombin complex formation. Effective TF silencing induced higher MSC differentiation in osteogenic and adipogenic media and showed stronger paracrine suppression of proinflammatory cytokines in macrophages and higher stimulation in the presence of endotoxins. Thus, TF silencing can produce functional cells with higher fidelity, efficacy, and functions.

Novel carboxylated ferrocene polymer nanocapsule with high reactive oxygen species sensitivity and on-demand drug release for effective cancer therapy

Multidrug resistance (MDR) is a major clinical issue leading to substantial reductions in the intracellular levels of anticancer drugs. To overcome MDR, stimulus-responsive polymeric nanotherapeutics that facilitate drug release and cellular uptake at target sites have emerged as promising tools for safe and effective cancer treatment. Among these nanotherapeutics, reactive oxygen species (ROS)-responsive nanocapsules are ideal carriers, as abnormally increased ROS levels can drive controlled drug release at target sites. In this study, we developed novel, high ROS-responsive carboxylated ferrocene nanocapsules (CFNCs) using solvents of different polarities for effective multidrug-resistant cancer therapy. The CFNCs were prepared via the self-assembly of an amphiphilic carboxylated ferrocene polymer composed of a hydrophilic COOH segment and a hydrophobic ferrocenylmethyl methacrylate segment possessing a ROS-responsive group. The size and ROS sensitivity of self-assembled CFNCs could be controlled by using solvents of different polarities during the simple nanoprecipitation process. The CFNCs showed a high loading content (approximately 30 wt%) and on-demand release of paclitaxel under both normal and tumor-mimicking conditions, and exhibited synergistic anticancer effects in multidrug-resistant colorectal cancer cells (HCT-15). Our findings suggest that CFNCs can be applied as carriers for effective cancer therapy.

Pluronic-based nanovehicles: Recent advances in anticancer therapeutic applications

Pluronics are a class of amphiphilic tri-block copolymers with wide pharmaceutical applicability. In the past decades, the ability to form biocompatible nanosized micelles was exploited to formulate stable drug nanovehicles with potential use in antitumor therapy. Due to the great potential for tuning physical and structural properties of Pluronic unimers, a panoply of drug or polynucleotide-loaded micelles was prepared and tested for their antitumoral activity. The attractive inherent antitumor properties of Pluronic polymers in combination with cell targeting and stimuli-responsive ligands greatly improved antitumoral therapeutic effects of tested drugs. In spite of that, the extraordinary complexity of biological challenges in the delivery of micellar drug payload makes their therapeutic potential still not exploited to the fullest. In this review paper we attempt to present the latest developments in the field of Pluronic based nanovehicles and their application in anticancer therapy with an overview of the chemistry involved in the preparation of these nanovehicles.

Nanoenabled Intracellular Calcium Bursting for Safe and Efficient Reversal of Drug Resistance in Tumor Cells

Multidrug resistance (MDR) of a tumor is the main cause of failure of clinical chemotherapy. Herein, we report a simple, yet versatile, tumor-targeting "calcium ion nanogenerator" (TCaNG) to reverse drug resistance by inducing intracellular Ca²⁺ bursting. Consequently, the TCaNG could induce Ca²⁺ bursting in acidic lysosomes of tumor cells and then reverse drug resistance according to the following mechanisms: (i) Ca²⁺ specifically accumulates in mitochondria, suppressing cellular respiration and relieving tumor hypoxia, thus inhibiting P-glycoprotein biosynthesis by downregulating HIF-1α expression. (ii) Ca²⁺-bursting-induced respiratory depression blocks intracellular ATP production, which further leads to the P-gp incompetence. As a result, the TCaNG could decrease the IC₅₀ of DOX to MCF-7/ADR cells by approximately 30 times and reduce the proliferation of drug-resistant tumors by approximately 13 times without obvious side effects. This simple, safe, and effective "Ca²⁺ bursting" strategy holds the potential for clinical application in tumor treatment.

Tumor Microenvironment-Triggered Charge Reversal Polymetformin-Based Nanosystem Co-Delivered Doxorubicin and IL-12 Cytokine Gene for Chemo-Gene Combination Therapy on Metastatic Breast Cancer

Cancer metastasis is the leading cause of high mortality and disease recurrence in breast cancer. In this study, a novel tumor microenvironment charge reversal polymetformin (PMet)-based nanosystem co-delivering doxorubicin (DOX) and plasmid encoding IL-12 gene (pIL-12) was developed for chemo-gene combination therapy on metastatic breast cancer. Cationic PMet was readily self-assembled into micelles for DOX physical encapsulation and pIL-12 complexation, and a hyaluronidase-sensitive thiolated hyaluronic acid (HA-SH) was then collaboratively assembled to the pIL-12/DOX-PMet micelleplexes, abbreviated as HA/pIL-12/DOX-PMet. DOX/pIL-12 loaded in HA/pIL-12/DOX-PMet micelleplexes presented prolonged circulation in blood, efficient accumulation in tumors, and internalization in tumor cells via CD44 receptor-mediated tumor specific-targeting, and DOX/pIL-12 was co-released in endo/lysosomes tumor microenvironment followed by HAase-triggered HA-SH deshielding from HA/pIL-12/DOX-PMet micelleplexes. Moreover, HA/PMet micelleplexes displayed excellent pIL-12 transfection and IL-12 expression in tumors of 4T1 tumor-bearing mice. Importantly, HA/pIL-12/DOX-PMet micelleplexes synergistically enhanced the NK cells and tumor infiltrated cytotoxic T lymphocytes and modulated the polarization from protumor M2 macrophages to activated antitumor M1 macrophages, with concomitant decreasing of the immunosuppressive regulatory T (Treg) cells, accompanied by an increase in the cytokines expression of IL-12, IFN-γ and TNF-α, consequently showing an improved antitumor and antimetastasis activity in 4T1 breast cancer lung metastasis mice model. In conclusion, the tumor microenvironment charge reversal HA/PMet nanosystem holds great promise for DOX/pIL-12 co-delivery and exploitation in chemo-gene combination therapy on metastatic breast cancer.

Nanotechnological approaches for counteracting multidrug resistance in cancer

Every year, cancer accounts for a vast portion of deaths worldwide. Established clinical protocols are based on chemotherapy, which, however, is not tumor-selective and produces a series of unbearable side effects in healthy tissues. As a consequence, multidrug resistance (MDR) can arise causing metastatic progression and disease relapse. Combination therapy has demonstrated limited responses in the treatment of MDR, mainly due to the different pharmacokinetic properties of administered drugs and to tumor heterogeneity, challenges that still need to be solved in a significant percentage of cancer patients. In this perspective, we briefly discuss the most relevant MDR mechanisms leading to therapy failure and we report the most advanced strategies adopted in the nanomedicine field for the design and evaluation of ad hoc nanocarriers. We present some emerging classes of nanocarriers developed to reverse MDR and discuss recent progress evidencing their limits and promises.

A dendritic, redox-responsive, supramolecular (Dr.S) system for lysis-triggered delivery for drug-resistant renal cancer

Purpose: Aiming to improve the drug loading capacity of dendritic nanoparticles and enhance delivery efficacy in drug-resistant cancer, we developed and optimized a more advanced dendritic, redox-responsive, supramolecular (Dr.S) system for intravenous RAD001 administration. Materials and methods: The Dr.S system was engineered by linking 3^rd generation polyamidoamine dendrimers (G3 PAMAM) with 8-arm polyethylene glycol (PEG) to encapsulate a molecular targeted agent RAD001. The drug-loading capacity was measured by ultraviolet-visible spectrophotometry. In vitro release behavior was determined with a two-compartment model, and the in vivo distribution pattern was tracked by Cy5.5 fluorescence. The therapeutic effect of Dr.S/RAD001 was evaluated in RAD001-resistant cancer cells and tumor-bearing nude mice, respectively. Results: The Dr.S system encapsulating RAD001 with a loading efficiency of 10.6% formed a core–shell structure, by shifting hydrophobic PAMAM/RAD001 components towards inner space and exposing the hydrophilic PEG on the surface. The Dr.S/RAD001 system could respond to a lysis-mimicking reduction stimulus, and functionally release cargoes to facilitate tumor accumulation and cellular internalization. These features contributed to the enhanced anti-tumor activity of RAD001 in renal cancers in vitro and in vivo. The Dr.S/RAD001 system also reversed acquired RAD001-resistance by a 60-fold increase in tumor accumulation of the therapeutics. Conclusion: The functional Dr.S/RAD001 system enables lysis-triggered release of RAD001 to achieve better tumor accumulation, which helps overcome acquired drug resistance in renal cancers.

Aiming to improve the drug loading capacity of dendritic nanoparticles and enhance delivery efficacy in drug-resistant cancer, we developed and optimized a more advanced dendritic, redox-responsive, supramolecular (Dr.S) system for intravenous RAD001 administration.

Novel Chitosan Derivatives with Reversible Cationization and Hydrophobicization for Tumor Cytoplasm-Specific Burst Co-delivery of siRNA and Chemotherapeutics

Despite the great potential of combination therapy based on siRNA and chemotherapeutics, an efficient vehicle with abilities of well drug co-loading, synchronizing in vivo trafficking, and target-specific co-burst release remains elusive, which results in a suboptimal synergistic potency. Herein, a novel chitosan amphiphile (PEI-ss-HECS-ss-OA, HSPO) with glutathione (GSH)-reversible cationization and hydrophobicization by polyethylenimine (PEI) and octylamine (OA), respectively, was developed for this purpose. HSPO spontaneously assembled in aqueous solution to be a micellar system and effectively co-encapsulated the two drugs with an adjustable dosage ratio. With a surface charge inversion strategy by hyaluronic acid (HA) coating, the HA(HSPO) co-delivery micelles with a negative surface charge (-21.45 ± 1.44 mV) and suitable size (192.52 ± 7.41 nm) selectively accumulated into CD44 overexpressed A549 tumors through a combination of passive and active targeting mechanism. Then, tumor cytoplasm-selective co-burst release was obtained through GSH triggered collapse of the amphiphilic assembly alongside a decrease of positive charge condensation, finally leading to an enhanced synergistic antitumor effect with a superior inhibition ratio of 86.63%. Overall, this study validated the great promise of HSPO as an efficient site-specific rapid co-trafficking vehicle of siRNA and chemotherapeutics for a remarkable synergistic tumor inhibition.

Enhancing the antivirus activity of chimeric canine interferon with ricin subunit B by using nanoparticle formulations

Despite interferon alpha having a broad spectrum of antiviral activity and strong antiproliferative activity, its applications are severely limited due to the intrinsic properties of proteins, such as poor stability and short serum half-life. In our study, canine interferon alpha (CaIFNα) gene was fused with the ricin toxin B chain (RTB) to form rCaIFNα/RTB, which encodes a 463-amino acid protein containing a 15-amino acid encoded (G₄S)₃ flexible linker. After expression in prokaryote, purification and renaturation, the cytotoxicity and antiviral activity of rCaIFNα/RTB were investigated in Madin–Darby canine kidney (MDCK) cells. rCaIFNα/RTB exerted a superior anti-vesicular stomatitis virus (VSV) activity on MDCK cells. Furthermore, we have developed a nanoparticle formulation of rCaIFNα/RTB by using polyethylenimine (PEI) through electrostatic interaction. rCaIFNα/RTB@PEI₁₀₀₀₀ is more stable than rCaIFNα/RTB at various pH and temperature levels, and it possesses enhanced antiviral activity. Our findings facilitate further research on the role of type I IFN in antiviral defense responses in Canis lupus familiaris.

Despite interferon alpha having a broad spectrum of antiviral activity and strong antiproliferative activity, its applications are severely limited due to the intrinsic properties of proteins, such as poor stability and short serum half-life.

pH-responsive polydopamine nanoparticles for photothermally promoted gene delivery

Recently, stimuli-responsive gene carriers have been widely studied to overcome the extra- and intracellular barriers in cancer treatment. In this study, we modified polydopamine nanoparticles with low-molecular weight polyethylenimine (PEI_1.8k) and polyethylene glycol-phenylboronic acid (PEG-PBA) to prepare pH-responsive gene carrier PDANP-PEI-rPEG. PBA and polydopamine could form pH-responsive boronate ester bonds. Non-responsive PDANP-PEI-nPEG and non-PEGylated PDANP-PEI were also studied as control. Both PDANP-PEI-rPEG/DNA and PDANP-PEI-nPEG/DNA complexes remained stable in the pH environment of blood circulation or extracellular delivery (pH 7.4) owing to the PEG modification. And after being internalized into endosomes, the boronate ester bonds could be cleaved. The pH responsive ability of PDANP-PEI-rPEG might facilitate complexes dissociation and gene release inside cells. The transfection level of PDANP-PEI-rPEG/DNA complexes was about 100 times higher than that of PDANP-PEI-nPEG/DNA complexes with the same mass ratios. Moreover, after NIR light irradiation at the power density of 2.6 W/cm² for 20 min, the good photothermal conversion ability of PDANP resulted in quick endosomal escape. The transfection level of PDANP-PEI-rPEG/DNA complexes doubled, even higher than that of lipofectamine 2000/DNA complexes. This was also confirmed by Bafilomycin A1 inhibition test and CLSM observation. In response to the acidic pH within cancer cells and the NIR light irradiation, the PDANP-PEI-rPEG carrier could overcome multiple obstacles in gene delivery, which was promising for further application in gene therapy.

Sequentially Site-Specific Delivery of Apoptotic Protein and Tumor-Suppressor Gene for Combination Cancer Therapy

Nanocarrier-mediated codelivery of multiple anticancer drugs is a potential strategy for enhanced efficacy of combination cancer treatment by unifying differential pharmacokinetic properties and maintaining an optimal ratio of drug cargoes. However, a programmable codelivery system is highly desired to deliver different therapeutics to their specific sites of action to pursue maximized combinational effect. Herein a liposome-based nanoassembly (p53/C-rNC/L-FA) is developed for intracellular site-specific delivery of an apoptotic protein cytochrome c (CytoC) and a plasmid DNA encoding tumor-suppressing p53 protein (p53 DNA). p53/C-rNC/L-FA consists of an acid-activated fusogenic liposomal membrane shell modified with folic acid (L-FA) and a DNA/protein complex core assembled by the p53 DNA, protamine and CytoC-encapsulated redox-responsive nanocapsule (C-rNC). Intratumoral and intraendosomal acidities promote membrane fusion between liposome and biomembrane, resulting in release of the encapsulated p53/C-rNC complex into the cytoplasm. The cytoplasmic reduction causes degradation of C-rNC with release of CytoC that induces tumor cell apoptosis. The p53 DNA is transported into the nucleus by the aid of the cationic protamine and thus generates expression of the p53 protein that enhances apoptosis combined with CytoC. p53/C-rNC/L-FA is demonstrated to significantly induce tumor cell apoptosis and inhibit tumor growth in the orthotopic breast tumor mouse model.

Tumor microenvironment as the "regulator" and "target" for gene therapy

In this review, we focus on strategies for designing functional nano gene carriers, as well as choosing therapeutic genes targeting the tumor microenvironment. Gene mutations have a great impact on the occurrence of cancer. Thus, gene therapy plays a major role in cancer therapy and has the potential to cure cancer. Well-designed gene therapy largely relies on effective gene carriers, which can be divided into viral carriers and non-viral carriers. A gene carrier delivers functional genes to their intracellular target and avoids nucleic acids being degraded by nucleases in the serum. Most conventional cancer gene therapies only target cancer cells and do not appear to be sufficintly efficient to pass clinical trials. Accumulating evidence has shown that extending the therapeutic strategies to the tumor microenvironment, rather than the tumor cell itself, can allow more options for achieving robust anti-cancer efficiency. In addition, unusual features between tumor microenvironment and normal tissues, such as a lower pH, higher glutathione and reactive oxygen species concentrations, and overexpression of some enzymes, facilitate the design of smart stimuli-responsive gene carriers regulated by the tumor microenvironment. These carriers interact with nucleic acids and then form stable nanoparticles under physiological conditions. By regulation of the tumor microenvironment, stimuli-responsive gene carriers are able to change their properties and achieve high gene delivery efficiency. Considering the tumor microenvironment as the "regulator" and "target" when designing gene carriers and choosing therapeutic genes shows significant benefit with respect to improving the accuracy and efficiency of cancer gene therapy.

Rising horizon in circumventing multidrug resistance in chemotherapy with nanotechnology

Multidrug resistance (MDR) is one of the key barriers in chemotherapy, leading to the generation of insensitive cancer cells towards administered therapy. Genetic and epigenetic alterations of the cells are the consequences of MDR, resulted in drug resistivity, which reflects in impaired delivery of cytotoxic agents to the cancer site. Nanotechnology-based nanocarriers have shown immense shreds of evidence in overcoming these problems, where these promising tools handle desired dosage load of hydrophobic chemotherapeutics to facilitate designing of safe, controlled and effective delivery to specifically at tumor microenvironment. Therefore, encapsulating drugs within the nano-architecture have shown to enhance solubility, bioavailability, drug targeting, where co-administered P-gp inhibitors have additionally combat against developed MDR. Moreover, recent advancement in the stimuli-sensitive delivery of nanocarriers facilitates a tumor-targeted release of the chemotherapeutics to reduce the associated toxicities of chemotherapeutic agents in normal cells. The present article is focused on MDR development strategies in the cancer cell and different nanocarrier-based approaches in circumventing this hurdle to establish an effective therapy against deadliest cancer disease.

Superior proapoptotic activity of curcumin-loaded mixed block copolymer micelles with mitochondrial targeting properties

Targeting tumor cell mitochondria is a prospective strategy for highly effective anticancer therapy. Consequently, the development of potent systems for the targeted delivery of mitochondria-acting therapeutics to mitochondria has the potential to boost this sector of nanomedicine. In this study, a functional mixed micellar system based on two co-assembled triblock copolymers, poly(2-(dimethylamino)ethyl methacrylate)-b-poly(ε-caprolactone)-b-poly(2-(dimethylamino)ethyl methacrylate) bearing triphenylphosphonium ligands (PDMAEMA(TPP+)20-b-PCL70-b-PDMAEMA(TPP+)20) and poly(ethylene oxide)-b-poly(ε-caprolactone)-b-poly(ethylene oxide) (PEO113-b-PCL70-b-PEO113), was assessed for the mitochondria targeted delivery of curcumin. The high proapoptotic activity of the system and the sub-cellular mechanisms of cytotoxicity were demonstrated using a chemosensitive HL-60 cell line and its resistant alternative HL-60/DOX. Next, the successful localization of nanocarriers in mitochondria was proved by fluorescence microscopy with the aid of DAPI (4',6-diamidino-2-phenylindole) as a cellular localization tracker. The in vitro experiments revealed the great potential of the functional system developed for the targeted delivery of curcumin to mitochondria, causing programmed tumor cell death.

Chemosensitization effect of cerium oxide nanosheets by suppressing drug detoxification and efflux

Cerium oxide (CeO₂) nanomaterials (NMs) have wide applications in biomedicine and are also detected with increasing bioaccumulation in various biological and environmental media. Thus, a system was developed to evaluate the chemosensitization effect of CeO₂ NMs. Herein, we discovered that low doses of CeO₂ NMs could trigger reactive oxygen species (ROS) production and decrease mitochondrial membrane potential (MMP) without causing severe toxicity to cancer cells, while pretreatment of the cells with CeO₂ NMs enhanced the toxicity of the chemotherapeutic agent doxorubicin (DOX). The reduced efflux of DOX was mainly attributed to adenosine triphosphate (ATP) depletion, followed by attenuation of exocytosis and enhancement of DOX retention. Further investigations revealed that CeO₂ NM-induced ROS production caused depletion of intracellular glutathione (GSH) and consequent impairment of DOX detoxification. Moreover, CeO₂ NMs were found to enhance the chemosensitization of cancer cells rather than normal cells. Thus, this study uncovered the underlying application potential of CeO₂ NMs in cancer therapy by enhancing the efficacy of chemotherapeutic agent, which is associated with disruption of mitochondrial function and impairment of drug detoxification.

Enhancing Antitumor Efficacy by Simultaneous ATP-Responsive Chemodrug Release and Cancer Cell Sensitization Based on a Smart Nanoagent

The exploitation of smart nanoagents based drug delivery systems (DDSs) has proven to be a promising strategy for fighting cancers. Hitherto, such nanoagents still face challenges associated with their complicated synthesis, insufficient drug release in tumors, and low cancer cell chemosensitivity. Here, the engineering of an adenosine triphosphate (ATP)-activatable nanoagent is demonstrated based on self-assembled quantum dots-phenolic nanoclusters to circumvent such challenges. The smart nanoagent constructed through a one-step assembly not only has high drug loading and low cytotoxicity to normal cells, but also enables ATP-activated disassembly and controlled drug delivery in cancer cells. Particularly, the nanoagent can induce cell ATP depletion and increase cell chemosensitivity for significantly enhanced cancer chemotherapy. Systematic in vitro and in vivo studies further reveal the capabilities of the nanoagent for intracellular ATP imaging, high tumor accumulation, and eventual body clearance. As a result, the presented multifunctional smart nanoagent shows enhanced antitumor efficacy by simultaneous ATP-responsive chemodrug release and cancer cell sensitization. These findings offer new insights toward the design of smart nanoagents for improved cancer therapeutics.

Polyethylenimine-based nanocarriers in co-delivery of drug and gene: a developing horizon

The meaning of gene therapy is the delivery of DNA or RNA to cells for the treatment or prevention of genetic disorders. The success rate of gene therapy depends on the progression and safe gene delivery system. The vectors available for gene therapy are divided into viral and non-viral systems. Viral vectors cause higher transmission efficiency and long gene expression, but they have major problems, such as immunogenicity, carcinogenicity, the inability to transfer large size genes and high costs. Non-viral gene transfer vectors have attracted more attention because they exhibit less toxicity and the ability to transfer large size genes. However, the clinical application of non-viral methods still faces some limitations, including low transmission efficiency and poor gene expression. In recent years, numerous methods and gene-carriers have been developed to improve gene transfer efficiency. The use of Polyethylenimine (PEI) based transfer of collaboration may create a new way of treating diseases and the combination of chemotherapy and gene therapy. The purpose of this paper is to introduce the PEI as an appropriate vector for the effective gene delivery.

Reduction-sensitive polymeric nanomedicines: An emerging multifunctional platform for targeted cancer therapy

The development of smart delivery systems that are robust in circulation and quickly release drugs following selective internalization into target cancer cells is a key to precision cancer therapy. Interestingly, reduction-sensitive polymeric nanomedicines showing high plasma stability and triggered cytoplasmic drug release behavior have recently emerged as one of the most exciting platforms for targeted delivery of various anticancer drugs including small chemical drugs, proteins, and nucleic acids. In vivo studies in varying tumor models reveal that these reduction-sensitive multifunctional nanomedicines outperform the currently used clinical formulations and reduction-insensitive counterparts, bringing about not only significantly enhanced tumor selectivity, accumulation and inhibition efficacy but also markedly reduced systemic toxicity and improved therapeutic index. In this review, we will highlight the cutting-edge advancement with a focus on in vivo performances as well as future perspectives on reduction-sensitive polymeric nanomedicines for targeted cancer therapy.

Advancements and Challenges in Multidomain Multicargo Delivery Vehicles

Reparative and regenerative processes are well-orchestrated temporal and spatial events that are governed by multiple cells, molecules, signaling pathways, and interactions thereof. Yet again, currently available implantable devices fail largely to recapitulate nature's complexity and sophistication in this regard. Herein, success stories and challenges in the field of layer-by-layer, composite, self-assembly, and core-shell technologies are discussed for the development of multidomain/multicargo delivery vehicles.

Stimuli-Responsive Nanomedicines for Overcoming Cancer Multidrug Resistance

Chemotherapy is still a main option for cancer therapy, but its efficacy is often unsatisfying due to multidrug resistance (MDR). The tumor microenvironment is considered a dominant factor causing MDR. Stimuli-responsive nanomedicines exhibit many superiorities for reversal of MDR. As smart systems, stimuli-responsive nanomedicines are desirable for achieving site-specific accumulation and triggered drug release in response to slight changes in physicochemical properties in pathological conditions or to exogenous stimuli. In this review, we highlight the current progress of various nanomedicines with different stimuli-responsive capabilities for overcoming MDR. The materials, design, construction as well as efficacy in overcoming MDR of these nanomedicines are discussed. Eventually, we look forward to forthcoming intelligent nanoparticle systems with new mechanisms to deliver drugs for practical applications in conquering cancer MDR.

Reactive oxygen species (ROS)-responsive nanomedicine for RNAi-based cancer therapy

Although much effort has been dedicated to the development of efficient siRNA delivery for cancer therapy, delivery nanomaterials that can particularly respond to reactive oxygen species (ROS), which are overproduced in the tissue and mitochondria of cancer cells, are still rare for the clinical translation of RNA interference (RNAi)-based therapy. To this end, we developed a ROS-responsive boronic vehicle with a lipid envelope for systemic vascular endothelial growth factor (VEGF) siRNA delivery so as to improve RNAi cancer therapy. We found that the efficiency of siRNA delivery largely relied on the ROS responsiveness of the carrier we have developed to mediate timely siRNA release, the PEG-functionalized lipid layer to shield the surface charge of polyplexes as well as the ability of the phenylboronic moiety to stabilize siRNA. The unique carrier nanostructure provides the efficient systemic transportation of siRNA to the tumor site for effective knockdown of the VEGF, which resulted in a significant antiangiogenesis effect and the effective inhibition of tumor growth in vivo. The current study defines a new systemic delivery strategy for siRNA by cooperatively integrating multifunctional lipid coatings with the ROS-responsive boronic polymer, which may potentially benefit RNAi-based therapy in the dawning era of precision nanomedicine for cancer therapy.