Tumor microenvironment-induced structure changing drug/gene delivery system for overcoming delivery-associated challenges

Research Progress of Disulfide Bond Based Tumor Microenvironment Targeted Drug Delivery System

Cancer poses a significant threat to human life and health. Chemotherapy is currently one of the effective cancer treatments, but many chemotherapy drugs have cell toxicity, low solubility, poor stability, a narrow therapeutic window, and unfavorable pharmacokinetic properties. To solve the above problems, target drug delivery to tumor cells, and reduce the side effects of drugs, an anti-tumor drug delivery system based on tumor microenvironment has become a focus of research in recent years. The construction of a reduction-sensitive nanomedicine delivery system based on disulfide bonds has attracted much attention. Disulfide bonds have good reductive responsiveness and can effectively target the high glutathione (GSH) levels in the tumor environment, enabling precise drug delivery. To further enhance targeting and accelerate drug release, disulfide bonds are often combined with pH-responsive nanocarriers and highly expressed ligands in tumor cells to construct drug delivery systems. Disulfide bonds can connect drug molecules and polymer molecules in the drug delivery system, as well as between different drug molecules and carrier molecules. This article summarized the drug delivery systems (DDS) that researchers have constructed in recent years based on disulfide bond drug delivery systems targeting the tumor microenvironment, disulfide bond cleavage-triggering conditions, various drug loading strategies, and carrier design. In this review, we also discuss the controlled release mechanisms and effects of these DDS and further discuss the clinical applicability of delivery systems based on disulfide bonds and the challenges faced in clinical translation.

Chitosan-Derived Nanocarrier Polymers for Drug Delivery and pH-Controlled Release in Type 2 Diabetes Treatment

Diabetes, particularly Type 2 Diabetes Mellitus (T2DM), is a chronic metabolic disorder with high and increasing global prevalence, characterized by insulin resistance and inadequate insulin secretion. Despite advancements in novel drug delivery systems, widespread and systematic treatment of advanced glycation end products (AGEs) remains challenging due to issues like drug toxicity, low water solubility, and uncontrolled release. Thus, developing nanoplatforms with controlled release capabilities has become a major research focus. Due to its excellent biocompatibility and drug delivery properties, chitosan has attracted considerable attention as a typical biopolymer. In this study, we designed and synthesized an intelligent fluorescence-pH sensitive nanopolymer material using chitosan. We loaded drug 1 and chromium phthalocyanine (CrPc) into folic acid-conjugated carboxymethyl chitosan (FA-CMCS) nanocarriers, forming FA-CMCS@1-CrPc. Comprehensive characterization of FA-CMCS@1-CrPc was conducted using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), and gas adsorption analysis (BET). The results indicate that the nanomaterial was successfully synthesized and exhibits excellent specific surface area, biocompatibility, and fluorescence response. Further research revealed that FA-CMCS@1-CrPc not only achieved controlled drug release but also could regulate drug release by adjusting pH. Additionally, due to its strong fluorescence performance, the nanomaterial demonstrated higher detection sensitivity, especially for monitoring the release of 5% trace drugs. An in vitro model of insulin-resistant cells was established to evaluate the effects of the drug delivery system on glucose degradation and AGE-RAGE regulation, providing a foundation for the development of new T2DM drugs.

Tumor Microenvironment-Responsive Polymer-Based RNA Delivery Systems for Cancer Treatment

Ribonucleic acid (RNA) therapeutics offer a broad prospect in cancer treatment. However, their successful application requires overcoming various physiological barriers to effectively deliver RNAs to the target sites. Currently, a number of RNA delivery systems based on polymeric nanoparticles are developed to overcome these barriers in RNA delivery. This work provides an overview of the existing RNA therapeutics for cancer gene therapy, and particularly summarizes those that are entering the clinical phase. This work then discusses the core features and latest research developments of tumor microenvironment-responsive polymer-based RNA delivery carriers which are designed based on the pathological characteristics of the tumor microenvironment. Finally, this work also proposes opportunities for the transformation of RNA therapies into cancer immunotherapy methods in clinical applications.

Glutathione Depletion and Stalwart Anticancer Activity of Metallotherapeutics Inducing Programmed Cell Death: Opening a New Window for Cancer Therapy

The cellular defense system against exogenous substances makes therapeutics inefficient as intracellular glutathione (GSH) exhibits an astounding antioxidant activity in scavenging reactive oxygen species (ROS) or reactive nitrogen species (RNS) or other free radicals produced by the therapeutics. In the cancer cell microenvironment, the intracellular GSH level becomes exceptionally high to fight against oxidative stress created by the production of ROS/RNS or any free radicals, which are the byproducts of intracellular redox reactions or cellular respiration processes. Thus, in order to maintain redox homeostasis for survival of cancer cells and their rapid proliferation, the GSH level starts to escalate. In this circumstance, the administration of anticancer therapeutics is in vain, as the elevated GSH level reduces their potential by reduction or by scavenging the ROS/RNS they produce. Therefore, in order to augment the therapeutic potential of anticancer agents against elevated GSH condition, the GSH level must be depleted by hook or by crook. Hence, this Review aims to compile precisely the role of GSH in cancer cells, the importance of its depletion for cancer therapy and examples of anticancer activity of a few selected metal complexes which are able to trigger cancer cell death by depleting the GSH level.

Recent Advances in Engineering Carriers for siRNA Delivery

RNA interference (RNAi) technology has been a promising treatment strategy for combating intractable diseases. However, the applications of RNAi in clinical are hampered by extracellular and intracellular barriers. To overcome these barriers, various siRNA delivery systems have been developed in the past two decades. The first approved RNAi therapeutic, Patisiran (ONPATTRO) using lipids as the carrier, for the treatment of amyloidosis is one of the most important milestones. This has greatly encouraged researchers to work on creating new functional siRNA carriers. In this review, the recent advances in siRNA carriers consisting of lipids, polymers, and polymer-modified inorganic particles for cancer therapy are summarized. Representative examples are presented to show the structural design of the carriers in order to overcome the delivery hurdles associated with RNAi therapies. Finally, the existing challenges and future perspective for developing RNAi as a clinical modality will be discussed and proposed. It is believed that the addressed contributions in this review will promote the development of siRNA delivery systems for future clinical applications.

[12]aneN3-modified camptothecin and PEGylated AIEgens co-assembly into core-shell nanoparticles with ROS/NTR dual-response for enhanced cancer therapy

A novel dual-responsive nanoparticle (NP) system was aimed to be developed for the co-delivery of camptothecin (CPT) and plasmid encoding TNF-related apoptosis-inducing ligand (pTRAIL) DNA in cancer therapy. The combination of the prodrug CPT and the nucleic acid condensing di-(triazole-[12]aneN3) unit with 4-nitrobenzyl ester through alkyl chains resulted in three nitroreductase (NTR) responsive amphiphiles, CNN1-CNN3 (with 5, 8, and 11 carbon chains, respectively). Among them, CNN2 was the most effective in inhibiting the proliferation of HeLa cells in the presence of fusogenic lipid DOPE. The NPs composed of CNN2, pDNA, and DOPE were further co-assembled with ROS-responsive thioketal-linked amphiphilic polymer (TTP) to afford the core-shell NPs (CNN2-DT/pDNA) with an average size of 118 nm, which exhibited high drug-loading capacity, excellent serum tolerance, and good biocompatibility. In the presence of ROS, NTR, and NADH, the core-shell NPs were decomposed, leading to the efficient release of 80% CPT and abundant pDNA. The self-assembly and delivery process of CNN2-DT NPs and DNA were clearly observed through the AIE fluorescent imaging. In vitro and in vivo results demonstrated that the CNN2-DT/pTRAIL NPs synergistically promoted 68% apoptosis of tumor cells and inhibited tumor growth with negligible toxic side effects. This study showed that the combination of prodrug and nucleic acid through dual-responsive core-shell NPs provide a spatially and temporally-controlled strategy for cancer therapy.

Glutathione and Esterase Dual-Responsive Smart Nano-drug Delivery System Capable of Breaking the Redox Balance for Enhanced Tumor Therapy

Conventional chemotherapy usually fails to achieve its intended effect because of the poor water solubility, poor tumor selectivity, and low tumor accumulation of chemotherapy drugs. The systemic toxicity of chemotherapy agents is also a problem that cannot be ignored. It is expected that smart nano-drug delivery systems that are able to respond to tumor microenvironments will provide better therapeutic outcomes with decreased side effects of chemotherapeutics. Nano-drug delivery systems capable of breaking the redox balance can also increase the sensitivity of tumor cells to chemotherapeutics. In this study, using polymer-containing disulfide bonds, ester bonds, and d-α-tocopherol polyethylene glycol succinate (TPGS), which can amplify reactive oxygen species (ROS) in tumor cells, we have successfully prepared a smart glutathione (GSH) and esterase dual-responsive nano-drug delivery system (DTX@PAMBE-SS-TPGS NPs) with the ability to deplete GSH as well as amplify ROS and effectively release an encapsulated chemotherapy drug (DTX) in tumor cells. The potential of DTX@PAMBE-SS-TPGS NPs for enhanced antitumor effects was thoroughly evaluated using in vitro as well as in vivo experiments. Our research offers a promising strategy for maximizing the efficacy of tumor therapy.

Dual size/charge-switchable and multi-responsive gelatin-based nanocluster for targeted anti-tumor therapy

Biopolymers with excellent biocompatibility and biodegradability show great potential for designing drug nanocarriers, while it's difficult to fabricate smart vehicles with multiple switching (size, surface, shape) based on biopolymers alone. Here, we report a dual size/charge-switchable and multi-responsive doxorubicin-loaded gelatin-based nanocluster (DOX-icluster) for improved tumor penetration and targeted anti-tumor therapy. The DOX-icluster was electrostatically assembled from folic acid and dimethylmaleic anhydride modified gelatin (FA-GelDMA) and small-sized DOX-loaded NH₂ modified hollow mesoporous organosilicon nanoparticles (DOX-HMON-NH₂). DOX-icluster had an initial size of about 199 nm at neutral pH. After accumulation in tumor tissue, the DMA bond of FA-GelDMA was cleaved and gelatin was degraded by matrix metalloproteinase (MMP-2), thus 48 nm and positively charged DOX-HMON-NH₂ was released to facilitate penetration and cell internalization. DOX-HMON-NH₂ was further degraded by intracellular glutathione (GSH) with releasing 48.1 % of DOX. The cellular uptake results indicated that the fabricated icluster promoted the uptake of DOX by 4T1 cells. With enhanced penetration efficacy, the tumor spheroids volume treated with DOX-icluster was reduced to 15.1 % on day 7. This cytocompatible multi-responsive gelatin-based icluster with size-shrinking and charge-reversible characteristics may be used as a significant drug carrier for tumor therapy.

Glutathione-responsive and -exhausting metal nanomedicines for robust synergistic cancer therapy

Due to their rapid and uncontrolled proliferation, cancer cells are characterized by overexpression of glutathione (GSH), which impairs reactive oxygen species (ROS)-based therapy and weakens the chemotherapeutic agent-induced toxification. Extensive efforts have been made in the past few years to improve therapeutic outcomes by depleting intracellular GSH. Special focus has been given to the anticancer applications of varieties of metal nanomedicines with GSH responsiveness and exhaustion capacity. In this review, we introduce several GSH-responsive and -exhausting metal nanomedicines that can specifically ablate tumors based on the high concentration of intracellular GSH in cancer cells. These include inorganic nanomaterials, metal-organic frameworks (MOFs), and platinum-based nanomaterials. We then discuss in detail the metal nanomedicines that have been extensively applied in synergistic cancer therapy, including chemotherapy, photodynamic therapy (PDT), sonodynamic therapy (SDT), chemodynamic therapy (CDT), ferroptotic therapy, and radiotherapy. Finally, we present the horizons and challenges in the field for future development.

PDT-sensitized ROS-responsive dextran nanosystem for maximizing antitumor potency of multi-target drugs

The heterogeneity of tumor microenvironment leads to uneven distribution of bio-stimuli. Thus, the multi-site delivery efficiency of responsive drug delivery systems (DDS) inner tumor was always limited. Herein, we proposed a combination strategy of photodynamic therapy (PDT) with ROS-responsive nanosystem which was constructed from dextran-phenylboronic acid pinacol ester conjugates. This combination utilized PDT to amplify and homogenize tissular oxidation level, and achieve effective multi-site response and release of multi-target drugs like gambogic acid (GA). Our research demonstrated the successful preparation of GA and protoporphyrin IX (PpIX) co-loaded nanoparticles, and the PDT-mediated spatiotemporal controlled multi-site drug release in simulated conditions. Furthermore, data from in vitro and in vivo researches on B16F10 cells, HUVEC, and B16F10-bearing C57BL/6 mice potently confirmed the enhanced multi-mechanism regulations of GA mediated by the effective and homogeneous tumoral release. This tactic based on bio-stimuli amplification and homogenization proposes a paradigm to maximize the potency of multi-target drugs.

Applications and challenges of ultra-small particle size nanoparticles in tumor therapy

With the development of nanotechnology, nanomedicines are widely used in tumor therapy. However, biological barriers in the delivery of nanoparticles still limit their application in tumor therapy. As one of the most fundamental properties of nanoparticles, particle size plays a crucial role in the process of the nanoparticles delivery process. It is difficult for large size nanoparticles with fixed size to achieve satisfactory outcomes in every process. In order to overcome the poor penetration of larger size, nanoparticles with ultra-small particle size are proposed, which are more conducive to deep tumor penetration and uniform drug distribution. In this review, the latest progresses and advantages of ultra-small nanoparticles are systematically summarized, the perspectives and challenges of ultra-small nanoparticles strategy for cancer treatment are also discussed.

Biomimetic macrophage membrane-coated gold-quantum dots with tumor microenvironment stimuli-responsive capability for tumor theranostic

Tumor microenvironment (TME) is intently related to tumor growth, progression and invasion, leading to drug resistance and insufficient therapeutic efficacy. However, remodeling TME and utilizing TME for exploring intelligent nanomaterials that can realize tumor theranostic is still challenging. Nowadays, the theranostic based on chemotherapy exposes some deficiencies, such as low targeting, weak permeability and premature clearance. Furthermore, it is challenging to cure drug-resistant tumors effectively. For the sake of solving these problems, a biomimetic decomposable nano-theranostic (MMV-Au-CDs-DOX) was well-established in this work. The Au-CDs are coated with macrophage-derived microvesicle to realize drug release accurately and enhance the biocompatibility of internal nanoparticles. Furthermore, MMV-Au-CDs-DOX would locate in the inflammation position of tumor, and disintegrate correspondingly into pieces with certain different functions stimulated by TME. Subsequently, the released anti-tumor nanodrugs were used for multimodal therapy, including chemotherapy and hemodynamic therapy. In addition, combined with the ability of Au-CDs to recognize GSH specifically, the off-on fluorescent probe was constructed to monitor the GSH of tumor cells and provided information on chemotherapy resistance.

Targeted drug delivery system for ovarian cancer microenvironment: Improving the effects of immunotherapy

Immunotherapies have shown modest benefits in the current clinical trials for ovarian cancer. The tumor microenvironment (TME) in an immunosuppressive phenotype contributes to this “failure” of immunotherapy in ovarian cancer. Many stromal cell types in the TME (e.g., tumor-associated macrophages and fibroblasts) have been identified as having plasticity in pro- and antitumor activities and are responsible for suppressing the antitumor immune response. Thus, the TME is an extremely valuable target for adjuvant interventions to improve the effects of immunotherapy. The current strategies targeting the TME include: 1) eliminating immunosuppressive cells or transforming them into immunostimulatory phenotypes and 2) inhibiting their immunosuppressive or pro-tumor production. Most of the effective agents used in the above strategies are genetic materials (e.g., cDNA, mRNA, or miRNA), proteins, or other small molecules (e.g., peptides), which are limited in their target and instability. Various formulations of drug delivery system (DDS) have been designed to realize the controlled release and targeting delivery of these agents to the tumor sites. Nanoparticles and liposomes are the most frequently exploited materials. Based on current evidence from preclinical and clinical studies, the future of the DDS is promising in cancer immunotherapy since the combination of agents with a DDS has shown increased efficacy and decreased toxicities compared with free agents. In the future, more efforts are needed to further identify the hallmarks and biomarkers in the ovarian TME, which is crucial for the development of more effective, safe, and personalized DDSs.

Engineered multifunctional nanocarriers for controlled drug delivery in tumor immunotherapy

The appearance of chemoresistance in cancer is a major issue. The main barriers to conventional tumor chemotherapy are undesirable toxic effects and multidrug resistance. Cancer nanotherapeutics were developed to get around the drawbacks of conventional chemotherapy. Through clinical evaluation of thoughtfully developed nano delivery systems, cancer nanotherapeutics have recently offered unmatched potential to comprehend and combat drug resistance and toxicity. In different design approaches, including passive targeting, active targeting, nanomedicine, and multimodal nanomedicine combination therapy, were successful in treating cancer in this situation. Even though cancer nanotherapy has achieved considerable technological development, tumor biology complexity and heterogeneity and a lack of full knowledge of nano-bio interactions remain important hurdles to future clinical translation and commercialization. The recent developments and advancements in cancer nanotherapeutics utilizing a wide variety of nanomaterial-based platforms to overcome cancer treatment resistance are covered in this article. Additionally, an evaluation of different nanotherapeutics-based approaches to cancer treatment, such as tumor microenvironment targeted techniques, sophisticated delivery methods for the precise targeting of cancer stem cells, as well as an update on clinical studies are discussed. Lastly, the potential for cancer nanotherapeutics to overcome tumor relapse and the therapeutic effects and targeted efficacies of modern nanosystems are analyzed.

The diffusion-driven microfluidic process to manufacture lipid-based nanotherapeutics with stealth properties for siRNA delivery

Our study investigated the manufacturing of lipid-based nanotherapeutics with stealth properties for siRNA delivery by employing a diffusion-driven microfluidic process in one or two-steps strategies to produce siRNA-loaded lipid nanocarriers and lipoplexes, respectively. In the one-step synthesis, siRNA in the aqueous phase is introduced from one inlet, while phospholipids dispersed in anhydrous ethanol are introduced from other inlets, generating the lipid nanocarriers. In the two-steps strategies, the pre-formed liposomes are complexed with siRNA. The process configuration with an aqueous diffusion barrier exerts a significant effect on the nanoaggregates synthesis. Dynamic light scattering data showed that lipid nanocarriers had a bigger particle diameter (298 ± 24 nm) and surface charge (43 ± 6 mV) compared to lipoplexes (194 ± 7 nm and 37.0 ± 0.4 mV). Moreover, DSPE-PEG(2000) was included in the formulation to synthesize lipid-based nanotherapeutics containing siRNA with stealth characteristics. The inclusion of PEG-lipid resulted in an increase in the surface charge of lipoplexes (from 33.7 ± 4.4-54.3 ± 1.6 mV), while a significant decrease was observed in the surface charge of lipid nanocarriers (30.3 ± 8.7 mV). The different structural assemblies were identified for lipoplex and lipid nanocarriers using Synchrotron SAXS. Lipid nanocarriers present a lower amount of multilayers than lipoplexes. Lipid-PEG insertion significantly influenced lipid nanocarriers' characteristics, drastically decreasing the number of multilayers. This effect was not observed in lipoplexes. The association between process configuration, lipid composition, and its effect on the characteristics of lipid-based vector systems can generate fundamental insights, contributing to gene-based nanotherapeutics development.

Approaches to Improve Macromolecule and Nanoparticle Accumulation in the Tumor Microenvironment by the Enhanced Permeability and Retention Effect

Passive targeting is the foremost mechanism by which nanocarriers and drug-bearing macromolecules deliver their payload selectively to solid tumors. An important driver of passive targeting is the enhanced permeability and retention (EPR) effect, which is the cornerstone of most carrier-based tumor-targeted drug delivery efforts. Despite the huge number of publications showcasing successes in preclinical animal models, translation to the clinic has been poor, with only a few nano-based drugs currently being used for the treatment of cancers. Several barriers and factors have been adduced for the low delivery efficiency to solid tumors and poor clinical translation, including the characteristics of the nanocarriers and macromolecules, vascular and physiological barriers, the heterogeneity of tumor blood supply which affects the homogenous distribution of nanocarriers within tumors, and the transport and penetration depth of macromolecules and nanoparticles in the tumor matrix. To address the challenges associated with poor tumor targeting and therapeutic efficacy in humans, the identified barriers that affect the efficiency of the enhanced permeability and retention (EPR) effect for macromolecular therapeutics and nanoparticle delivery systems need to be overcome. In this review, approaches to facilitate improved EPR delivery outcomes and the clinical translation of novel macromolecular therapeutics and nanoparticle drug delivery systems are discussed.

The Intracellular and Extracellular Microenvironment of Tumor Site: The Trigger of Stimuli-Responsive Drug Delivery Systems

The tumor microenvironment (TME), including intracellular and extracellular microenvironment, contains many biochemical indicators (such as acidity/alkalinity, oxygen content, and enzymatic activity) that are different from the normal physiological environment. These abnormal biochemical indicators can accelerate the heterogeneity of tumors, but on the other hand, they also provide opportunities for the design of intelligent drug delivery systems (DDSs). The TME-responsive DDSs have shown great potential in reducing the side effects of chemotherapy and improving the curative effect of tumors. In this review, the abnormal biochemical indicators of TME are introduced in detail from both the extracellular and intracellular aspects. In view of the various physiological barriers encountered during drug delivery, the strategy of constructing TME-responsive DDSs is discussed. By summarizing the typical research progress, the authors prospect the development of TME-responsive DDS in the future.

Construction of a New Dual-Responsive Nano-Drug Delivery System for Matrix Metalloproteinases and Adenosine Triphosphate in Ovarian Cancer Using Nanomicelles

In this manuscript we constructed a dual-responsive nano-drug delivery system for matrix metalloproteinases and ATP in ovarian cancer microenvironment. The nanomicelle PCL-DNA/DOX-Peptide-PEG was prepared by intercalating doxorubicin hydrochloride between C and G base pairs of DNA double helix structure. Another ATP-responsive nanomicelle PCL-DNA/DOX-PEG was prepared. Then we analyzed the characterization of nanomicelles (particle size, potential, surface morphology, etc.) and drug loading binding and drug release behavior. In addition, the effect of nanomicelles on the viability of mouse ovarian epithelial tumor cell ID-8 was detected by CCK-8 method. CCK-8 assay detected that different concentrations of carrier had no difference on the proliferation of ID-8 cells, and the survival rate of ID-8 cells by different concentrations of DOX preparations was statistically significant and the same results were observed in cytotoxicity comparison. Confocal microscopy showed that DOX in the drug-loaded micelle group was concentrated in the nucleus, while free DOX was concentrated in the cytoplasm. ID-8 cells took up the drug-loaded micelles faster. The semi-quantitative analysis of the DOX uptake of ID-8 cells with different treatments showed extremely significant statistical differences. In conclusion, the prepared self-assembled dual-responsive nanomicelle PCL-DNA/DOX-Peptide-PEG is novel anti-tumor agent, and is expected to have good tumor tissue penetration ability with a low toxicity.

Polydopamine-coated nanocomposite theranostic implants for localized chemotherapy and MRI imaging

Sustained and localized delivery of chemotherapeutics in postoperative cancer treatment leads to a radical improvement in prognosis and a much decreased risk of tumor recurrence. In this work, polydopamine (PDA)-coated superparamagnetic iron oxide nanoparticle (SPION)-loaded polycaprolactone and poly (lactic-co-glycolic acid) fibers were developed as a potential implant to ensure safe and sustained release of the chemotherapeutic drug methotrexate (MTX), as well as provide local contrast for magnetic resonance imaging (MRI). Fibres were prepared by co-axial electrospinning and loaded with MTX-layered double hydroxide (LDH) nanocomposites in the core, yielding organic-inorganic hybrids ranging from 1.23 to 1.48 µm in diameter. After surface coating with PDA, SPIONs were subsequently loaded on the fibre surface and found to be evenly distributed, providing high MRI contrast. In vitro drug release studies showed the PDA coated fibres gave sustained release of MTX over 18 days, and the release profile is responsive to conditions representative of the tumor microenvironment such as slightly acidic pH values or elevated concentrations of the reducing agent glutathione (GSH). In vitro studies with Caco-2 and A549 cells showed highly effective killing with the PDA coated formulations, which was further enhanced at higher levels of GSH. The fibres hence have the potential to act as an implantable drug-eluting platform for the sustained release of cytotoxic agents within a tumor site, providing a novel treatment option for post-operative cancer patients.

Polysaccharide hydrogels regulate macrophage polarization and enhance the anti-tumor efficacy of melanoma

Chemotherapy occupies a prominent position in combination treatments of melanoma. However, the severe systemic side effects and the pro-tumorigenic microenvironment limited its therapeutic efficacy. In the present study, polysaccharide hydrogels (SCOD) were constructed by N-succinyl chitosan and oxidized dextran through Schiff-base formation to deliver doxorubicin (Dox) locally. The gelation time and mechanical properties of SCOD hydrogels could be fine-tuned by varying concentration of precursor solutions. Rheological data revealed that SCOD hydrogels possessed injectable shear-shinning property and remarkable self-healing capability. It also could be degraded by lysozyme widely present in body fluids. Moreover, SCOD hydrogels were readily loaded with Dox in precursor solutions and released drug over 1 week in a pH-dependent manner. The ability of Dox-loaded SCOD hydrogels to inhibit the growth of murine B16 and human A375 melanoma was verified by in vitro assays. Strikingly, Dox-loaded SCOD hydrogels were found to efficiently induce polarization of tumor-associated macrophages towards M1 phenotype that favors an anti-tumorigenic tumor microenvironment. Notably, in vivo experiments demonstrated that locally injected Dox-loaded SCOD hydrogels exhibited excellent anti-tumor activity against B16 melanoma, outperforming Dox at equivalent doses administrated intravenously. Therefore, the injectable and self-healing polysaccharide hydrogels are a promising strategy to improve locoregional control in melanoma.

Tumor microenvironment based stimuli-responsive CRISPR/Cas delivery systems: A viable platform for interventional approaches

The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) systems have emerged as robust tools in cancer gene therapy due to their simplicity and versatility. Nevertheless, the genome editing efficiency in tumor sites and the clinical applications of CRISPR/Cas have been compromised by non-specific delivery and genotoxicity. Recently, intelligent delivery systems incorporating sensitive materials in response to endogenous stimuli of the tumor microenvironment (TME) have represented viable platforms for tumor-specific genome editing and reduced side effects of CRISPR/Cas. Spurred by this promising direction, this review first introduces the CRISPR/Cas systems widely employed in cancer therapeutic explorations. Various types of CRISPR/Cas delivery systems sensitive to the stimuli in TME and typical dual-/multiple-responsive CRISPR/Cas carriers are further discussed, emphasizing the correlations between sensitive components and spatiotemporal delivery mechanisms. The genome editing efficiencies of CRISPR/Cas-loaded stimuli-responsive carriers are also summarized both in vitro and in vivo. Collectively, stimuli-responsive CRISPR/Cas delivery systems hold great promise for potent cancer gene therapy.

Engineering nanotheranostic strategies for liver cancer

The incidence and mortality of hepatocellular carcinoma have continued to increase over the last few years, and the medicine-based outlook of patients is poor. Given great ideas from the development of nanotechnology in medicine, especially the advantages in the treatments of liver cancer. Some engineering nanoparticles with active targeting, ligand modification, and passive targeting capacity achieve efficient drug delivery to tumor cells. In addition, the behavior of drug release is also applied to the drug loading nanosystem based on the tumor microenvironment. Considering clinical use of local treatment of liver cancer, in situ drug delivery of nanogels is also fully studied in orthotopic chemotherapy, radiotherapy, and ablation therapy. Furthermore, novel therapies including gene therapy, phototherapy, and immunotherapy are also applied as combined therapy for liver cancer. Engineering nonviral polymers to function as gene delivery vectors with increased efficiency and specificity, and strategies of co-delivery of therapeutic genes and drugs show great therapeutic effect against liver tumors, including drug-resistant tumors. Phototherapy is also applied in surgical procedures, chemotherapy, and immunotherapy. Combination strategies significantly enhance therapeutic effects and decrease side effects. Overall, the application of nanotechnology could bring a revolutionary change to the current treatment of liver cancer.

Rapid pH-responsive self-disintegrating nanoassemblies balance tumor accumulation and penetration for enhanced anti-breast cancer therapy

The dilemma of tumor accumulation and deep penetration has always been a barrier in antitumor therapy. Stimuli-responsive size changeable drug delivery systems provide possible solutions. Nevertheless, the low size-shrinkage efficiency limited the antitumor effects. In this study, an instant pH-responsive size shrinkable nanoassemblies named self-aggregated DOX@HA-CD (SA-DOX@HA-CD) was formulated using small-sized hyaluronic acid modified carbon dots (HA-CD) as monomers, which could self-aggregate into raspberry-like structure via hydrophobicity force in neutral pH and rapidly disassemble into shotgun-like DOX-loaded CD monomer in simulated tumor microenvironment (pH 6.5), owing to the transformation in electrical charge and hydrophobicity/hydrophilicity of this system. The transmission electron microscopy showed that the clustered SA-DOX@HA-CD had a diameter of ~150 nm, and thoroughly disassembled into ~30 nm nanoparticles in response to acidic environment. The disassemble efficiency was approximately 100%. Attributed to this property, SA-DOX@HA-CD led to enhanced cellular internalization and accumulation in 4T1 cells in simulated tumor microenvironment, as well as deep tumor penetration in 3D tumor spheroid model. Besides, the imine bond between DOX and HA-CD endowed DOX with pH-responsive release profile in the acidic lysosome environment. Furthermore, in the orthotopic 4T1 tumor-bearing mouse model, SA-DOX@HA-CD demonstrated higher tumor accumulation than non-aggregated DOX-HA-CD. Meanwhile, in response to the acid tumor microenvironment, the dissociated DOX-HA achieved deep tumor penetration, which consequently resulted in 2.5-fold higher antitumor efficiency. The formulation of self-aggregated SA-DOX@HA-CD provides a simple and effective alternative to prepare pH-responsive size-shrinkable nanodrug delivery systems. STATEMENT OF SIGNIFICANCE: The heterogeneity of tumor vasculature and the high tumor interstitial pressure lead to the barriers in tumor accumulation and deep penetration, which calls for opposite properties (e.g. size) of drug delivery systems. To address this dilemma, various size changeable nanoparticles have been developed utilizing special features of tumor microenvironment, such as pH, enzyme and reactive oxygen species. Nevertheless, the current strategies face the problems of incomplete hydrolysis of chemical bonds or insufficient enzyme degradation, which result in only partial size shrinkage, hindering the tumor deep penetration effects. Here we developed a self-assembled nanocluster, which could respond to acidic pH rapidly and thoroughly disassemble into small nanodots due to the alteration of hydrophobicity/hydrophilicity/charge, leading to approximately 100% dissociation. This strategy provides a new concept for design of size changeable drug delivery systems.

Aminopeptidase N-targeting nanomolecule-assisted delivery of VEGF siRNA to potentiate antitumour therapy by suppressing tumour revascularization and enhancing radiation response

Tumour revascularization and the consequent radioresistance activated by the up-regulated angiogenic pathway after radiation exposure remain a major bottleneck for improving the tumouricidal effect of radiotherapy (RT) in hepatocellular carcinoma (HCC). Herein, we show that fabricated aminopeptidase N (ANP/CD13)-targeting Gd-hybridized gold nanomolecules (tGd-GNMs) can efficaciously suppress tumour revascularization and the consequent radioresistance, and then synergize in augmenting the RT response. Both in vitro and in vivo experiments demonstrate that the targeted delivery of vascular endothelial growth factor (VEGF) siRNA into the tumour site and the generation of an abundance of intratumourally cytotoxic reactive oxygen species (ROS) under X-ray radiation by the tGd-GNMs_siRNA complex has the capability to down-regulate VEGF gene expression and strengthen the radiation response. Furthermore, the tGd-GNMs_siRNA complex contributes to excellent active tumour targeting ability, remarkably enhancing tumour contrast in the fluorescence, computed tomography (CT) and magnetic resonance (MR) imaging modalities in real-time with a long imaging time window. Overall, the synthesized tGd-GNMs_siRNA complex with excellent potentiation of the antitumour ability and real-time multimodal imaging ability represents a promising visualized theranostic nanoplatform for the treatment of HCC.

Application of glutathione depletion in cancer therapy: Enhanced ROS-based therapy, ferroptosis, and chemotherapy

Glutathione (GSH) is an important member of cellular antioxidative system. In cancer cells, a high level of GSH is indispensable to scavenge excessive reactive oxygen species (ROS) and detoxify xenobiotics, which make it a potential target for cancer therapy. Plenty of studies have shown that loss of intracellular GSH makes cancer cells more susceptible to oxidative stress and chemotherapeutic agents. GSH depletion has been proved to improve the therapeutic efficacy of ROS-based therapy (photodynamic therapy, sonodynamic therapy, and chemodynamic therapy), ferroptosis, and chemotherapy. In this review, various strategies for GSH depletion used in cancer therapy are comprehensively summarized and discussed. First, the functions of GSH in cancer cells are analyzed to elucidate the necessity of GSH depletion in cancer therapy. Then, the synthesis and metabolism of GSH are briefly introduced to bring up some crucial targets for GSH modulation. Finally, different approaches to GSH depletion in the literature are classified and discussed in detail according to their mechanisms. Particularly, functional materials with GSH-consuming ability based on nanotechnology are elaborated due to their unique advantages and potentials. This review presents the ingenious application of GSH-depleting strategy in cancer therapy for improving the outcomes of various therapeutic regimens, which may provide useful guidance for designing intelligent drug delivery system.

Targeted Delivery of Drugs and Genes Using Polymer Nanocarriers for Cancer Therapy

Cancer is one of the primary causes of worldwide human deaths. Most cancer patients receive chemotherapy and radiotherapy, but these treatments are usually only partially efficacious and lead to a variety of serious side effects. Therefore, it is necessary to develop new therapeutic strategies. The emergence of nanotechnology has had a profound impact on general clinical treatment. The application of nanotechnology has facilitated the development of nano-drug delivery systems (NDDSs) that are highly tumor selective and allow for the slow release of active anticancer drugs. In recent years, vehicles such as liposomes, dendrimers and polymer nanomaterials have been considered promising carriers for tumor-specific drug delivery, reducing toxicity and improving biocompatibility. Among them, polymer nanoparticles (NPs) are one of the most innovative methods of non-invasive drug delivery. Here, we review the application of polymer NPs in drug delivery, gene therapy, and early diagnostics for cancer therapy.

Black phosphorus assisted polyionic micelles with efficient PTX loading for remotely controlled release and synergistic treatment of drug-resistant tumors

Nanomedicines have been widely used in the effective delivery of chemotherapeutic drugs due to their advantages such as increasing the half-life of drugs, selectively targeting tumor tissues, and thus reducing systemic toxicity. However, the low drug entrapment rate and the difficulty of real-controlled release at tumor sites hinder their further clinical translations. Here we have developed biodegradable polyionic micelles (PD-M) to facilitate black phosphorus (BP) encapsulation (PD-M@BP) for improved drug loading. With the introduction of BP, PTX-loaded PD-M@BP (PD-M@BP/PTX) with sizes of 124-162 nm exhibited superior encapsulation efficiency over 94% and excellent colloidal stability. Meanwhile, PD-M well protected BP from fast degradation to show the good photothermal performance under near-infrared (NIR) irradiation, thus achieving the remotely controlled fast PTX release due to micelle core melting and dissociation, accompanied by the synergistic photothermal tumor therapy. The in vivo results demonstrated that the PD-M@BP/PTX nanosystem not only realized significant inhibition of multi-drug resistant (MDR) cervical tumors (HeLa/PTXR tumor) by remote NIR-regulation, but also reduced the potential damage of chemotherapeutic drugs to the whole body, rendering these hybrid nanosystems as great tools to treat MDR tumors synergistically.

Co-delivery of autophagy inhibitor and gemcitabine using a pH-activatable core-shell nanobomb inhibits pancreatic cancer progression and metastasis

Background: Metastasis is one of the main reasons for the high mortality associated with pancreatic ductal adenocarcinoma (PDAC), and autophagy regulates the metastatic migration of tumor cells, their invasion of tissues, and their formation of focal adhesions. Inhibiting autophagy may suppress tumor growth and metastasis, but the abundant extracellular matrix hinders the deep penetration of therapeutic agents. Methods: To enhance the penetration of drugs that can inhibit metastasis of pancreatic cancer, a pH-responsive drug delivery system was formulated. Gemcitabine (GEM), a first-line chemotherapeutic drug against PDAC, was loaded in 6PA-modified DGL (PDGL) nanoparticles to afford PDGL-GEM. Then PDGL-GEM was co-precipitated with the autophagy inhibitor chloroquine phosphate (CQ) and calcium phosphate to formulate PDGL-GEM@CAP/CQ. The size and morphology of the resulting "nanobomb" PDGL-GEM@CAP/CQ were characterized, and their uptake into cells, cytotoxicity and ability to inhibit autophagy were analyzed at pH 6.5 and 7.4. The anti-tumor and anti-metastasis effects of the nanobomb were explored on mice carrying Pan 02 pancreatic tumor xenografts or orthotopic tumors. Results: The pH-induced dissolution of calcium phosphate facilitated the release of CQ from the nanobomb and deep penetration of PDGL-GEM. The internalization of PDGL-GEM and subsequent intracellular release of GEM inhibited tumor growth, while CQ downregulated autophagy in tumor cells and fibroblasts. In fact, inhibition of xenograft and orthotopic tumor growth was greater with the complete PDGL-GEM@CAP/CQ than with subassemblies lacking GEM or CQ. More importantly, mechanistic studies in vitro and in vivo suggested that the nanobomb inhibits metastasis by downregulating MMP-2 and paxillin, as well as reducing fibrosis. Conclusion: The pH-sensitive PDGL-GEM@CAP/CQ shows potential for inhibiting proliferation and metastasis of pancreatic cancer through an autophagy-dependent pathway.

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.

Recent progress on charge-reversal polymeric nanocarriers for cancer treatments

Nanocarriers (NCs) for delivery anticancer therapeutics have been under development for decades. Although great progress has been achieved, the clinic translation is still in the infancy. The key challenge lies in the biological barriers which lie between the NCs and the target spots, including blood circulation, tumor penetration, cellular uptake, endo-/lysosomal escape, intracellular therapeutics release and organelle targeting. Each barrier has its own distinctive microenvironment and requires different surface charge. To address this challenge, charge-reversal polymeric NCs have been a hot topic, which are capable of overcoming each delivery barrier, by reversing their charges in response to certain biological stimuli in the tumor microenvironment. In this review, the triggering mechanisms of charge reversal, including pH, enzyme and redox approaches are summarized. Then the corresponding design principles of charge-reversal NCs for each delivery barrier are discussed. More importantly, the limitations and future prospects of charge-reversal NCs in clinical applications are proposed.

A size-tunable nanoplatform: enhanced MMP2-activated chemo-photodynamic immunotherapy based on biodegradable mesoporous silica nanoparticles

Although immunotherapy is emerging as a revolutionary strategy for cancer therapy, its clinical effect is severely impaired by adaptive immune evasion and inefficient activation of antitumor immune response. Photodynamic therapy and chemotherapy have been shown to efficiently enhance the therapeutic effect of PD-L1 immunotherapy via different mechanisms. However, the lack of a precise drug delivery system seriously impedes the clinical application of combination therapy. To address these restrictions, a matrix metalloproteinases-2 (MMP2)-activated shrinkable nanosystem was developed to potentiate the antitumor efficacy of anti-PD-L1 antibody (aPDL1) delivered along with a chemo-photodynamic therapy. The nanosystem maintains its structure to accelerate tumor accumulation and shrinks down to a smaller size to facilitate tumor penetration and cellular uptake upon arriving in the tumor microenvironment. The exposure of aPDL1 on the surface of the biodegradable mesoporous silica cores (bMSNs) blocks the PD-1/PD-L1 interaction between tumor cells and T cells. Meanwhile, photosensitizer chlorin e6 (Ce6) and paclitaxel (PTX) loaded bMSNs effectively enter tumor cells and induce chemo-photodynamic therapy. The nanosystem elicits a chemo-photodynamic-induced immune response and improves the therapeutic effect of PD-L1 blockade mediated by aPDL1. Furthermore, the nanosystem displays a sustained prohibitive effect on tumor metastasis to distant sites. Our work presents a promising strategy for enhancing the efficacy of cancer immunotherapy.

Polymeric micelles amplify tumor oxidative stresses through combining PDT and glutathione depletion for synergistic cancer chemotherapy

Cancer has been one of the major healthcare burdens, which demands innovative therapeutic strategies to improve the treatment outcomes. Combination therapy hold great potential to leverage multiple synergistic pathways to improve cancer treatment. Cancer cells often exhibit an increased generation of reactive oxygen species (ROS) and antioxidant species compared with normal cells, and the levels of these species can be further elevated by common therapeutic modalities such as photodynamic therapy (PDT) or chemotherapy. Taking advantage that cancer cells are vulnerable to further oxidative stress, we aim to design a drug delivery system by simultaneously increasing the cellular ROS level, reducing antioxidative capacity, and inducing anticancer chemotherapy in cancer cells. Here, we designed a star-shape polymer, PEG(-b-PCL-Ce6)-b-PBEMA, based on the Passerini three-component reaction, which can both enhance ROS generation during PDT and decrease the GSH level in cancer cells. The polycaprolactone conjugated with photosensitizer Ce6 served as hydrophobic segments to promote micelle formation, and Ce6 was used for PDT. The H₂O₂-labile group of arylboronic esters pendent on the third segment was designed for H₂O₂-induced quinone methide (QM) release for GSH depletion. We thoroughly investigated the spectral properties of blank micelle during its assembling process, ROS generation, and H₂O₂-induced QM release in vitro. Moreover, this polymeric micelle could successfully load hydrophobic anticancer drug Doxorubicin (DOX) and efficiently deliver DOX into cancer cells. The triple combination of ROS generation, GSH elimination, and chemotherapy dramatically improved antitumor efficiency relative to each of them alone in vitro and in vivo.

A paclitaxel and microRNA-124 coloaded stepped cleavable nanosystem against triple negative breast cancer

Background

Triple negative breast cancer (TNBC) is one of the most biologically aggressive breast cancers and lacks effective treatment options, resulting in a poor prognosis. Therefore, studies aiming to explore new therapeutic strategies for advanced TNBC are urgently needed. According to recent studies, microRNA-124 (miR124) not only inhibits tumour growth but also increases the sensitivity of TNBC to paclitaxel (PTX), suggesting that a platform combining PTX and miR124 may be an advanced solution for TNBC.

Results

Herein, we constructed a stepped cleavable calcium phosphate composite lipid nanosystem (CaP/LNS) to codeliver PTX and miR124 (PTX/miR124-NP). PTX/miR124-NP exhibited superior tumor microenvironment responsive ability, in which the surface PEG layer was shed in the mildly acidic environment of tumor tissues and exposed oligomeric hyaluronic acid (o-HA) facilitated the cellular uptake of CaP/LNS by targeting the CD44 receptor on the surface of tumor cells. Inside tumour cells, o-HA detached from CaP/LNS due to the reduction of disulfide bonds by glutathione (GSH) and inhibited tumour metastasis. Then, PTX and miR124 were sequentially released from CaP/LNS and exerted synergistic antitumour effects by reversing the Epithelial-Mesenchymal Transition (EMT) process in MDA-MB-231 cells. Moreover, PTX/miR124-NP showed significant antitumour efficiency and excellent safety in mice bearing MDA-MB-231 tumours.

Conclusion

Based on these results, the codelivery of PTX and miR124 by the CaP/LNS nanosystem might be a promising therapeutic strategy for TNBC.

Platinum (II)-coordinated Portulaca oleracea polysaccharides as metal-drug based polymers for anticancer study

Novel polysaccharide-platinum conjugated polymers bearing alendronate on Portulaca oleracea polysaccharides (PPS) were designed and synthesized. Their chemical structures and properties were characterized by Fourier transform infrared spectroscopy (FT-IR), ¹H NMR and ³¹P NMR spectroscopy, Thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), UV-vis spectrophotometer (UV-vis) and other analysis methods. The results demonstrated that alendronate can be used as the linker of Portulaca oleracea polysaccharides and platinum compounds. Portulaca oleracea polysaccharides-alendronate (PPS-ALN) conjugates exhibited stronger antioxidant ability than PPS. The cytotoxicity assay to cancer cells was tested in vitro, and the Portulaca oleracea polysaccharides-alendronate-platinum (PPS-ALN-Pt) conjugates strongly inhibited the proliferation of cancer cells than PPS and PPS-ALN. The evaluation of complexes affinity toward supercoiled plasmid DNA, displayed a high DNA interaction. Interestingly, the platinum conjugates displayed immunological competence in HeLa cells by cellular immunofluorescence assay. Besides, the cellular platinum accumulation of PPS-ALN-Pt conjugates was higher than that of cisplatin in HeLa cells, implying that the polysaccharide-platinum conjugated polymers might have a synergistically therapeutic application in metal anticancer drug delivery.

Pre- and Post-Transcriptional Regulation of cFLIP for Effective Cancer Therapy Using pH-Ultrasensitive Nanoparticles

Cellular FLIP (cFLIP) is a crucial player of apoptosis-regulated pathways that is frequently overexpressed in solid cancers. To inhibit c-FLIP, pre- and post-transcriptionally, a multifunctional nanoparticle (NP) was created to deliver cFLIP-specific small interfering RNA (siRNA) into cancer cells. Specifically, Vorinostat (Vor)-loaded mesoporous silica nanoparticles (MSN) were conjugated with polyethylenimine-biotin (PB), followed by electrostatically binding with cFLIP siRNA (Vor/siR@MSN-PB). To stabilize and prolong the circulation time of nanoparticles, a bialdehyde-modified poly(ethylene glycol) (PEG) was cross-linked onto the polyethylenimine (PEI) backbone via the formation of the imine linkage (Schiff base) (Vor/siR@MSN-PB-PEG). The Schiff base is highly stable at physiological pH 7.4 but labile under slightly acidic pH conditions. In the acidic tumor microenvironment (TME), the PEG outer layer could be rapidly cleaved, resulting in the switching of the nanoparticle surface charge to positive, which specifically enhances internalization of the NPs to the biotin-positive tumor cells. Our results demonstrated the successful preparation of Vor/siR@MSN-PB-PEG NPs, in which the siRNA was effectively protected in serum and regulated the expression of cFlip, post-transcriptionally. The presence of the PEG layer resulted in high tumor accumulation and high efficacy in tumor inhibition, which was a result of the efficient cFLIP suppression. Furthermore, in the low-dose regimen of Vorinostat-the pre-transcriptional cFLIP suppressor, treatment with Vor/siR@MSN-PB-PEG NPs was found to be safe with the treated mice, indicating a promising combination regimen for cancer therapy.

Combined cancer therapeutics-Tackling the complexity of the tumor microenvironment

Cancer treatment has yet to find a "silver bullet" capable of selectively and effectively kill tumor cells without damaging healthy cells. Nanomedicine is a promising field that can combine several moieties in one system to produce a multifaceted nanoplatform. The tumor microenvironment (TME) is considered responsible for the ineffectiveness of cancer therapeutics and the difficulty in the translation from the bench to bed side of novel nanomedicines. A promising approach is the use of combinatorial therapies targeting the TME with the use of stimuli-responsive nanomaterials which would increase tumor targeting. Contemporary combined strategies for TME-targeting nanoformulations are based on the application of external stimuli therapies, such as photothermy, hyperthermia or ultrasounds, in combination with stimuli-responsive nanoparticles containing a core, usually composed by metal oxides or graphene, and a biocompatible stimuli-responsive coating layer that could also contain tumor targeting moieties and a chemotherapeutic agent to enhance the therapeutic efficacy. The obstacles that nanotherapeutics must overcome in the TME to accomplish an effective therapeutic cargo delivery and the proposed strategies for improved nanotherapeutics will be reviewed. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Assembly and Detachment of Hyaluronic Acid on a Protein-Conjugated Gold Nanoparticle

The assembly-disassembly of hyaluronic acid (HA) with a bovine serum albumin-conjugated gold nanoparticle (BSA-AuNP) was demonstrated using a gas-phase electrophoresis approach, electrospray-differential mobility analysis (ES-DMA). Physical sizes, number and mass concentrations, and degrees of aggregation of HA, BSA, and AuNP were successfully quantified using ES-DMA hyphenated with inductively coupled plasma mass spectrometry. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was employed complementarily for an orthogonal characterization of the assembly of HA with BSA-AuNP and the subsequent HA detachment. The results show that the surface packing density of HA on BSA-AuNP was proportional to the concentration of HA (C_HA) when C_HA ≤ 5 × 10^-3 μmol/L, and the equilibrium binding constant of HA on BSA-AuNP was identified as ≈ 4 × 10⁵ L/mol at pH 3. The pH-sensitive and enzyme-induced detachments of HA from BSA-AuNP were both successfully characterized using ES-DMA and ATR-FTIR. In the absence of enzymatic catalysis, the rate constant of HA detachment (k) was shown to increase by at least 3.7 times on adjusting the environmental acidity from pH 3 to pH 7. A significant enzyme-induced HA detachment was identified at pH 7, showing a remarkable increase of k by at least two times in the presence of an enzyme. This work provides a proof of concept for assembly of HA-based hybrid colloidal nanomaterials through the tuning of surface chemistry in the aqueous phase with the ability of in situ quantitative characterization, which has shown promise for the development of a variety of HA-derivative biomedical applications (e.g., drug delivery).

Versatile Types of Polysaccharide-Based Drug Delivery Systems: From Strategic Design to Cancer Therapy

Chemotherapy is still the most direct and effective means of cancer therapy nowadays. The proposal of drug delivery systems (DDSs) has effectively improved many shortcomings of traditional chemotherapy drugs. The technical support of DDSs lies in their excellent material properties. Polysaccharides include a series of natural polymers, such as chitosan, hyaluronic acid, and alginic acid. These polysaccharides have good biocompatibility and degradability, and they are easily chemical modified. Therefore, polysaccharides are ideal candidate materials to construct DDSs, and their clinical application prospects have been favored by researchers. On the basis of versatile types of polysaccharides, this review elaborates their applications from strategic design to cancer therapy. The construction and modification methods of polysaccharide-based DDSs are specifically explained, and the latest research progress of polysaccharide-based DDSs in cancer therapy are also summarized. The purpose of this review is to provide a reference for the design and preparation of polysaccharide-based DDSs with excellent performance.

Tumor microenvironment responsive supramolecular glyco-nanovesicles based on diselenium-bridged pillar[5]arene dimer for targeted chemotherapy

Supramolecular glyco-nanovesicles (SeSe-(P5)2⊃Man-NH3+) based on the host-guest complex of a diselenium-bridged pillar[5]arene dimer and a mannose derivative have been successfully developed for the first time, which possessed tumor microenvironment-responsiveness and specific targetability due to their diselenium bonds and mannose units, respectively.

Cancer Nanomedicine Special Issue Review Anticancer Drug Delivery with Nanoparticles: Extracellular Vesicles or Synthetic Nanobeads as Therapeutic Tools for Conventional Treatment or Immunotherapy

Both natural and synthetic nanoparticles have been proposed as drug carriers in cancer treatment, since they can increase drug accumulation in target tissues, optimizing the therapeutic effect. As an example, extracellular vesicles (EV), including exosomes (Exo), can become drug vehicles through endogenous or exogenous loading, amplifying the anticancer effects at the tumor site. In turn, synthetic nanoparticles (NP) can carry therapeutic molecules inside their core, improving solubility and stability, preventing degradation, and controlling their release. In this review, we summarize the recent advances in nanotechnology applied for theranostic use, distinguishing between passive and active targeting of these vehicles. In addition, examples of these models are reported: EV as transporters of conventional anticancer drugs; Exo or NP as carriers of small molecules that induce an anti-tumor immune response. Finally, we focus on two types of nanoparticles used to stimulate an anticancer immune response: Exo carried with A Disintegrin And Metalloprotease-10 inhibitors and NP loaded with aminobisphosphonates. The former would reduce the release of decoy ligands that impair tumor cell recognition, while the latter would activate the peculiar anti-tumor response exerted by γδ T cells, creating a bridge between innate and adaptive immunity.