Stealth CD44-targeted hyaluronic acid supramolecular nanoassemblies for doxorubicin delivery: probing the effect of uncovalent pegylation degree on cellular uptake and blood long circulation

Hyaluronic Acid Receptor-Mediated Nanomedicines and Targeted Therapy

Hyaluronic acid (HA) is a naturally occurring polysaccharide found in the extracellular matrix with broad applications in disease treatment. HA possesses good biocompatibility, biodegradability, and the ability to interact with various cell surface receptors. Its wide range of molecular weights and modifiable chemical groups make it an effective drug carrier for drug delivery. Additionally, the overexpression of specific receptors for HA on cell surfaces in many disease states enhances the accumulation of drugs at pathological sites through receptor binding. In this review, the modification of HA with drugs, major receptor proteins, and the latest advances in receptor-targeted nano drug delivery systems (DDS) for the treatment of tumors and inflammatory diseases are summarized. Furthermore, the functions of HA with varying molecular weights of HA in vivo and the selection of drug delivery methods for different diseases are discussed.

Hydrogen-bonded cytosine-endowed supramolecular polymeric nanogels: Highly efficient cancer cell targeting and enhanced therapeutic efficacy

We demonstrate that cytosine moieties within physically cross-linked supramolecular polymers not only manipulate drug delivery and release, but also confer specific targeting of cancer cells to effectively enhance the safety and efficacy of chemotherapy-and thus hold significant potential as a new perspective for development of drug delivery systems. Herein, we successfully developed physically cross-linked supramolecular polymers (PECH-PEG-Cy) comprised of hydrogen-bonding cytosine pendant groups, hydrophilic poly(ethylene glycol) side chains, and a hydrophobic poly(epichlorohydrin) main chain. The polymers spontaneously self-assemble into a reversibly hydrogen-bonded network structure induced by cytosine and directly form spherical nanogels in aqueous solution. Nanogels with a high hydrogen-bond network density (i.e., a higher content of cytosine moieties) exhibit outstanding long-term structural stability in cell culture substrates containing serum, whereas nanogels with a relatively low hydrogen-bond network density cannot preserve their structural integrity. The nanogels also exhibit numerous unique physicochemical characteristics in aqueous solution, such as a desirable spherical size, high biocompatibility with normal and cancer cells, excellent drug encapsulation capacity, and controlled pH-responsive drug release properties. More importantly, in vitro experiments conclusively indicate the drug-loaded PECH-PEG-Cy nanogels can selectively induce cancer cell-specific apoptosis and cell death via cytosine receptor-mediated endocytosis, without significantly harming normal cells. In contrast, control drug-loaded PECH-PEG nanogels, which lack cytosine moieties in their structure, can only induce cell death in cancer cells through non-specific pathways, which significantly inhibits the induction of apoptosis. This work clearly demonstrates that the cytosine moieties in PECH-PEG-Cy nanogels confer selective affinity for the surface of cancer cells, which enhances their targeted cellular uptake, cytotoxicity, and subsequent induction of programmed cell death in cancer cells.

Chitosan- and hyaluronic acid-based nanoarchitectures in phototherapy: Combination cancer chemotherapy, immunotherapy and gene therapy

Cancer phototherapy has been introduced as a new potential modality for tumor suppression. However, the efficacy of phototherapy has been limited due to a lack of targeted delivery of photosensitizers. Therefore, the application of biocompatible and multifunctional nanoparticles in phototherapy is appreciated. Chitosan (CS) as a cationic polymer and hyaluronic acid (HA) as a CD44-targeting agent are two widely utilized polymers in nanoparticle synthesis and functionalization. The current review focuses on the application of HA and CS nanostructures in cancer phototherapy. These nanocarriers can be used in phototherapy to induce hyperthermia and singlet oxygen generation for tumor ablation. CS and HA can be used for the synthesis of nanostructures, or they can functionalize other kinds of nanostructures used for phototherapy, such as gold nanorods. The HA and CS nanostructures can combine chemotherapy or immunotherapy with phototherapy to augment tumor suppression. Moreover, the CS nanostructures can be functionalized with HA for specific cancer phototherapy. The CS and HA nanostructures promote the cellular uptake of genes and photosensitizers to facilitate gene therapy and phototherapy. Such nanostructures specifically stimulate phototherapy at the tumor site, with particle toxic impacts on normal cells. Moreover, CS and HA nanostructures demonstrate high biocompatibility for further clinical applications.

Functionalized zein nanoparticles targeting neonatal Fc receptor to enhance lung absorption of peptides

Peptides have a distinguished therapeutic potential for several chronic conditions, and more than 80 peptides exist in the global market. However, most of these marketed peptide drugs are currently delivered intravenously or subcutaneously due to their fast degradation and limited absorption through non-invasive routes. The pulmonary route is favored as a non-invasive route. Neonatal Fc receptor (FcRn) is expressed in adult human lungs and has a role in enhancing the pulmonary absorption of monoclonal antibodies. In this work, we developed and characterized candidate protein delivery systems for the pulmonary administration of peptides. The prepared bare and loaded zein nanoparticles (ZNPs), targeted, physically, and covalently PEGylated ZNPs showed hydrodynamic diameters between 137 and 155 nm and a narrow distribution index. Insulin, which was used as a protein model, showed an association efficiency of 72%, while the FcRn-targeted peptide conjugation efficiency was approximately 68%. The physically adsorbed poloxamer 407 on insulin-loaded ZNPs showed slower and controlled insulin release. The in vitro cell culture model consists of the NCI-H441 epithelial cell line, which confirmed its expression of the targeted receptor, FcRn. The safety of ZNPs was verified after incubation with both cell lines of the in vitro pulmonary model, namely NCI-H441 and HPMEC-ST1.6R, for 24 h. It was observed that targeted ZNPs enhanced insulin permeability by showing a higher apparent permeation coefficient than non-targeted ZNPs. Overall, both targeted PEGylated ZNPs showed to be suitable peptide carriers and adequately fit the demands of delivery systems designed for pulmonary administration.

Role of Micelle Size in Cell Transcytosis-Based Tumor Extravasation, Infiltration, and Treatment Efficacy

Transcytosis-based active transport of cancer nanomedicine has shown great promise for enhancing its tumor extravasation and infiltration and antitumor activity, but how the key nanoproperties of nanomedicine, particularly particle size, influence the transcytosis remains unknown. Herein, we used a transcytosis-inducing polymer, poly[2-(N-oxide-N,N-diethylamino)ethyl methacrylate] (OPDEA), and fabricated stable OPDEA-based micelles with different sizes (30, 70, and 140 nm in diameter) from its amphiphilic block copolymer, OPDEA-block-polystyrene (OPDEA-PS). The study of the micelle size effects on cell transcytosis, tumor extravasation, and infiltration showed that the smallest micelles (30 nm) had the fastest transcytosis and, thus, the most efficient tumor extravasation and infiltration. So, the 7-ethyl-10-hydroxyl camptothecin (SN38)-conjugated OPDEA micelles of 30 nm had much enhanced antitumor activity compared with the 140 nm micelles. These results are instructive for the design of active cancer nanomedicine.

Preparation and evaluation of astaxanthin-loaded 2-hydroxypropyl-beta-cyclodextrin and Soluplus® nanoparticles based on electrospray technology

BACKGROUND

Astaxanthin is a type of food-derived active ingredient with antioxidant, antidiabetic and non-toxicity functions, but its poor solubility and low bioavailability hinder further application in food industry. In the present study, through inclusion technologies, micellar solubilization and electrospray techniques, we prepared astaxanthin nanoparticles before optimizing the formulation to regulate the physical and chemical properties of micelles. We accomplished the preparation of astaxanthin nanoparticle delivery system based on single needle electrospray technology through use of 2-hydroxypropyl-β-cyclodextrin and Soluplus® to improveme the release behavior of the nanocarrier.

RESULTS

Through this experiment, we successfully prepared astaxanthin nanoparticles with a particle size of approximately 80 nm, which was further verified with scanning electron microscopy and transmission electron microscopy. Furthermore, the encapsulation of astaxanthin molecules into the carrier nanoparticles was verified via the results of attenuated total reflectance intensity and X-ray powder diffraction techniques. The in vitro release behavior of astaxanthin nanoparticles was different in media that contained 0.5% Tween 80 (pH 1.2, 4.5 and 6.8) buffer solution and distilled water. Also, we carried out a pharmacokinetic study of astaxanthin nanoparticles, in which it was observed that astaxanthin nanoparticle showed an effect of immediate release and significant improved bioavailability.

CONCLUSION

2-hydroxypropyl-β-cyclodextrin and Soluplus® were used in the present study as a hydrophilic nanocarrier that could provide a simple way of encapsulating natural function food with repsect to improving the solubility and bioavailability of poorly water-soluble ingredients. © 2023 Society of Chemical Industry.

Self-assembled thioether-bridged paclitaxel-dihydroartemisinin prodrug for amplified antitumor efficacy-based cancer ferroptotic-chemotherapy

Ferroptosis has been proposed as one form of iron-dependent cell death, overgeneration of high-toxicity hydroxyl radicals (˙OH) tumor sites via Fenton reactions induced cell membrane damage. However, the insufficient intracellular concentrations of both iron and H₂O₂ limited the anticancer performance of ferroptosis. In this study, ROS-sensitive prodrug nanoassemblies composed of a PEG2000-ferrous compound and a single thioether bond bridged dihydroartemisinin-paclitaxel prodrug were constructed, which fully tapped ex/endogenous iron, ferroptosis inducers, and chemotherapeutic agents. Following cellular uptake, the intracellular oxidizing environment accelerated the self-destruction of nanoassemblies and triggered drug release. In addition to the chemotherapeutic effect, the activated dihydroartemisinin was capable of acting as a toxic ˙OH amplifier via the reinforced Fenton reaction, simultaneously depleting intracellular GSH, as well as inducing glutathione peroxidase 4 inactivation, further enhancing ferroptosis-dependent cancer cell proliferation inhibition. Meanwhile, the ROS generation-inductive and cell cycle arrest effect from the paclitaxel augmented synergetic ferroptotic-chemotherapy of cancer. Thus, the prodrug integrating dihydroartemisinin with paclitaxel via a single thioether bond represents a potent nanoplatform to exert amplified ferroptotic-chemotherapy for improved anticancer efficacy.

B16F10 Cell Membrane-Based Nanovesicles for Melanoma Therapy Are Superior to Hyaluronic Acid-Modified Nanocarriers

Some cancer cell membrane (CCM)-derived nanovesicles show strong homing effects and are used for targeted cancer therapy. By co-constructing the B16F10 cell membrane with a PEGylated phospholipid membrane, a new nanocarrier with a composite nanocrown structure was developed, which can evade immune recognition and actively target homologous melanoma. The nanocrowns have an encapsulation efficiency of more than 90% for paclitaxel and showed no significant difference (p > 0.05) from the PEGylated phospholipid membrane vesicles. Compared with the hyaluronic acid-modified PEGylated phospholipid membrane vesicles, the biomimetic nanocrowns enhanced the escape of nanovesicles from reticuloendothelial cells in vitro and extended the circulation time in vivo; moreover, the nanocrowns showed superior melanoma-targeted drug delivery capability and improved anticancer effects of paclitaxel as demonstrated by the inhibition of B16F10 cell proliferation and induction of apoptosis by interfering with microtubule formation. In contrast, the modification of hyaluronic acid did not increase the targeting capacity or antitumor effects of the nanocrowns, confirming that the superior targeting capacity was mediated by the exposed homologous CCMs rather than by hyaluronic acid. Our results demonstrate the potential of using biomimetic nanocrowns for active melanoma-targeted therapy.

Hyaluronic Acid-Functionalized Mesoporous Silica Nanoparticles Loading Simvastatin for Targeted Therapy of Atherosclerosis

Atherosclerosis (AS) constitutes a major threat to human health, yet most current therapeutics are hindered in achieving desirable clinical outcomes by low bioavailability or serious side effects. Herein, we constructed an enzyme-responsive and macrophage-targeting drug delivery system (SIM@HA-MSN) which can potentially modulate the microenvironment of the atherosclerotic plaques characterized by excessive inflammation and overexpression of hyaluronidase (HAase) for precise AS treatment. More specifically, mesoporous silica nanoparticles (MSNs) were loaded with a lipid-lowering drug simvastatin (SIM) and further gated with hyaluronic acid (HA) coating, which endowed the nanosystem with HAase responsiveness and targetability to inflammatory macrophages. Our results showed that a high loading efficiency (>20%) and excellent enzyme-responsive release of SIM were simultaneously achieved for the first time by silica-based nanocarriers through formulation optimizations. Moreover, in vitro experiments confirmed that SIM@HA-MSN possessed robust targeting, anti-inflammatory, and anti-foaming effects, along with low cytotoxicity and excellent hemocompatibility. In addition, preliminary animal experiments demonstrated the as-established nanosystem had a long plasma-retention time and good biocompatibility in vivo. Taken together, SIM@HA-MSN with HA playing triple roles including gatekeeping, lesion-targeting, and long-circulating holds great potential for the management of atherosclerosis.

Toxicity Assessment of Mesoporous Silica Nanoparticles upon Intravenous Injection in Mice: Implications for Drug Delivery

Nanoparticles are popular tools utilized to selectively deliver drugs and contrast agents for identification and treatment of disease. To determine the usefulness and translational potential of mesoporous silica nanoparticles (MSNs), further evaluations of toxicity are required. MSNs are among the most utilized nano-delivery systems due to ease of synthesis, pore structure, and functionalization. This study aims to elucidate toxicity as a result of intravenous injection of 25 nm MSNs coated with chitosan (C) or polyethylene glycol (PEG) in mice. Following acute and chronic injections, blood was evaluated for standard blood chemistry and complete blood count analyses. Blood chemistry results primarily indicated that no abnormalities were present following acute or chronic injections of MSNs, or C/PEG-coated MSNs. After four weekly administered treatments, vital organs showed minor exacerbation of pre-existing lesions in the 35KPEG-MSN and moderate exacerbation of pre-existing lesions in uncoated MSN and 2KPEG-MSN treatment groups. In contrast, C-MSN treatment groups had minimal changes compared to controls. This study suggests 25 nm MSNs coated with chitosan should elicit minimal toxicity when administered as either single or multiple intravenous injections, but MSNs coated with PEG, especially 2KPEG may exacerbate pre-existing vascular conditions. Further studies should evaluate varying sizes and types of nanoparticles to provide a better overall understanding on the relation between nanoparticles and in vivo toxicity.

Nanostructured particles assembled from natural building blocks for advanced therapies

Advanced treatments based on immune system manipulation, gene transcription and regulation, specific organ and cell targeting, and/or photon energy conversion have emerged as promising therapeutic strategies against a range of challenging diseases. Naturally derived macromolecules (e.g., proteins, lipids, polysaccharides, and polyphenols) have increasingly found use as fundamental building blocks for nanostructured particles as their advantageous properties, including biocompatibility, biodegradability, inherent bioactivity, and diverse chemical properties make them suitable for advanced therapeutic applications. This review provides a timely and comprehensive summary of the use of a broad range of natural building blocks in the rapidly developing field of advanced therapeutics with insights specific to nanostructured particles. We focus on an up-to-date overview of the assembly of nanostructured particles using natural building blocks and summarize their key scientific and preclinical milestones for advanced therapies, including adoptive cell therapy, immunotherapy, gene therapy, active targeted drug delivery, photoacoustic therapy and imaging, photothermal therapy, and combinational therapy. A cross-comparison of the advantages and disadvantages of different natural building blocks are highlighted to elucidate the key design principles for such bio-derived nanoparticles toward improving their performance and adoption. Current challenges and future research directions are also discussed, which will accelerate our understanding of designing, engineering, and applying nanostructured particles for advanced therapies.

Dual-Loaded Liposomes Tagged with Hyaluronic Acid Have Synergistic Effects in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most lethal subtypes of breast cancer. Although chemotherapy is considered the most effective strategy for TNBC, most chemotherapeutics in current use are cytotoxic, meaning they target antiproliferative activity but do not inhibit tumor cell metastasis. Here, a TNBC-specific targeted liposomal formulation of epalrestat (EPS) and doxorubicin (DOX) with synergistic effects on both tumor cell proliferation and metastasis is described. These liposomes are biocompatible and effectively target tumor cells owing to hyaluronic acid (HA) modification on their surface. This active targeting, mediated by CD44-HA interaction, allows DOX and EPS to be delivered simultaneously to tumor cells in vivo, where they suppress not only TNBC tumor growth and the epithelial-mesenchymal transition, but also cancer stem cells, which collectively suppress tumor growth and metastasis of TNBC and may also act to prevent relapse of TNBC.

Case ReportPaclitaxel-loaded TPGS2k/Gelatin-grafted Cyclodextrin/Hyaluronic acid-grafted Cyclodextrin nanoparticles for oral bioavailability and targeting enhancement

The clinical applications of paclitaxel (PTX), a natural compound with broad-spectrum antitumor effects, have been markedly limited owing to its poor oral bioavailability and lack of targeting ability. Recently, several drug carriers, such as TPGS_2k, gelatin (Gel), cyclodextrin (CD), and hyaluronic acid (HA), have been identified as promising enhancers of drug efficacy. Therefore, Gel-grafted CD (GEL-CD) and HA-grafted CD (HA-CD) were synthesized via grafting, and PTX-loaded TPGS_2k/GEL-CD/HA-CD nanoparticles (TGHC-PTX-NPs) were successfully prepared using the ultrasonic crushing method. The mean particles size, polydispersity index, and Zeta potential of TGHC-PTX-NPs were 253.57 ± 2.64 nm, 0.13 ± 0.03, and 0.087 ± 0.005 mV, respectively. TGHC-PTX-NPs with an encapsulation efficiency of 61.77 ± 0.47% and a loading capacity of 6.86 ± 0.32% appeared round and uniformly dispersed based on transmission electron microscopy. In vitro release data revealed that TGHC-PTX-NPs had good sustained-release properties. Further, TGHC-PTX-NPs had increased the targeted uptake by HeLa cells as HA can specifically bind to the CD44 receptor at the cell surface, and its intestinal absorption is related to caveolin-mediated endocytosis. The pharmacokinetic results indicated that TGHC-PTX-NPs significantly enhanced the absorption of PTX in vivo compared to the PTX suspension, with a relative bioavailability of 227.21%. Such findings indicate the potential of TGHC-PTX-NPs for numerous clinical applications.

Facile fabrication and characterization of kenaf core as natural biochar for the highly efficient removal of selected endocrine-disrupting compounds

This study aims to formulate and fabricate the optimum condition of modified kenaf core (MKC) for the removal of targeted endocrine-disrupting compounds in a batch adsorption system. Kenaf core was chemically modified using phosphoric acid as an activating agent, which involved the pyrolysis step. Results indicated a significant difference (p < 0.05) for unmodified and novel modified biochar, observed in characteristic performance analysis via ultimate analysis, Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR) spectrum, and Brunauer-Emmett-teller (BET) surface area. The removal percentage of 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) in individual and binary mixture systems was examined in order to ascertain the highest removal percentage for MKC application in an aqueous solution. The main and interaction effects of three prepared variables such as incorporate of impregnation concentration of an acid catalyst (0.1-1.0 M), particle size (45-1,000 µm), and dosage (1.0-20.0 g/L) were examined and statistically analyzed via design of experiment (DoE) through developed quadratic models. The removal efficiency of E2 and EE2 in an individual system leads to T₂KC > T₁KC > T₃KC, whereas that in the binary mixture system leads to T₂KC > T₁KC > T₃KC and T₁KC > T₂KC > T₃KC for E2 and EE2 adsorption, respectively, through hydrogen bonding and the π-π interaction mechanism. Thus, the findings revealed T₂KC at a moderate level of acid concentration (0.5 M H₃PO₄) to be a potential biochar, with an environmentally safe and sound profile for opposing emerging pollutant issues as well as for the attainment of sustainable development goals.

Tumor-penetrating iron oxide nanoclusters for T1/T2 dual mode MR imaging-guided combination therapy

A hyaluronic acid (HA)-stabilized iron oxide nanocluster (Fe2O3@PFDH NC) was developed as an intelligent tumor-penetrating theranostic nanoagent for dual-mode MRI guided chemo-photothermal therapy.

Polymeric nanostructures based on azobenzene and their biomedical applications: synthesis, self-assembly and stimuli-responsiveness

Amphiphilic polymers can self-assemble to form nanoparticles with different structures under suitable conditions. Polymer nanoparticles functionalized with aromatic azo groups are endowed with photo-responsive properties. In recent years, a variety of photoresponsive polymers and nanoparticles have been developed based on azobenzene, using different molecular design strategies and synthetic routes. This article reviews the progress of this rapidly developing research field, focusing on the structure, synthesis, assembly and response of photo-responsive polymer assemblies. According to the molecular structure, photo-responsive polymers can be divided into linear polymers containing azobenzene in a side chain, linear polymers containing azobenzene in the main chain, linear polymers containing azobenzene in an end group, branched polymers containing azobenzene and supramolecular polymers containing azobenzene. These systems have broad biomedical application prospects in the field of drug delivery and imaging applications.

Bone Regeneration Using MMP-Cleavable Peptides-Based Hydrogels

Accumulating evidence has suggested the significant potential of chemically modified hydrogels in bone regeneration. Despite the progress of bioactive hydrogels with different materials, structures and loading cargoes, the desires from clinical applications have not been fully validated. Multiple biological behaviors are orchestrated precisely during the bone regeneration process, including bone marrow mesenchymal stem cells (BMSCs) recruitment, osteogenic differentiation, matrix calcification and well-organized remodeling. Since matrix metalloproteinases play critical roles in such bone metabolism processes as BMSC commitment, osteoblast survival, osteoclast activation matrix calcification and microstructure remodeling, matrix metalloproteinase (MMP) cleavable peptides-based hydrogels could respond to various MMP levels and, thus, accelerate bone regeneration. In this review, we focused on the MMP-cleavable peptides, polymers, functional modification and crosslinked reactions. Applications, perspectives and limitations of MMP-cleavable peptides-based hydrogels for bone regeneration were then discussed.

Understanding Drug Delivery to the Brain Using Liposome-Based Strategies: Studies that Provide Mechanistic Insights Are Essential

Brain drug delivery may be restricted by the blood-brain barrier (BBB), and enhancement by liposome-based drug delivery strategies has been investigated. As access to the human brain is limited, many studies have been performed in experimental animals. Whereas providing interesting data, such studies have room for improvement to provide mechanistic insight into the rate and extent of specifically BBB transport and intrabrain distribution processes that all together govern CNS target delivery of the free drug. This review shortly summarizes BBB transport and current liposome-based strategies to overcome BBB transport restrictions, with the emphasis on how to determine the individual mechanisms that all together determine the time course of free drug brain concentrations, following their administration as such, and in liposomes. Animal studies using microdialysis providing time course information on unbound drug in plasma and brain are highlighted, as these provide the mechanistic information needed to understand BBB drug transport of the drug, and the impact of a liposomal formulations of that drug on BBB transport. Overall, these studies show that brain distribution of a drug administered as liposomal formulation depends on both drug properties and liposomal formulation characteristics. In general, evidence suggests that active transporters at the BBB, either being influx or efflux transporters, are circumvented by liposomes. It is concluded that liposomal formulations may provide interesting changes in BBB transport. More mechanistic studies are needed to understand relevant mechanisms in liposomal drug delivery to the brain, providing an improved basis for its prediction in human using animal data.

Fabrication of pH/Reduction Sensitive Polyethylene Glycol-Based Micelles for Enhanced Intracellular Drug Release

At present, the drug is still difficult to release completely and quickly only with single stimulation. In order to promote the rapid release of polymeric micelles at tumor site, pH/reduction sensitive polymers (PCT) containing disulfide bonds and orthoester groups were synthesized. The PCT polymers can self-assemble in water and entrap doxorubicin to form drug-loaded micelles (DOX/PCT). In an in vitro drug release experiment, the cumulative release of DOX/PCT micelles in the simulated tumor microenvironment (pH 5.0 with GSH) reached (89.7 ± 11.7)% at 72 h, while it was only (16.7 ± 6.1)% in the normal physiological environment (pH 7.4 without GSH). In addition, pH sensitive DOX loaded micellar system (DOX/PAT) was prepared as a control. Furthermore, compared with DOX/PAT micelles, DOX/PCT micelles showed the stronger cytotoxicity against tumor cells to achieve an effective antitumor effect. After being internalized by clathrin/caveolin-mediated endocytosis and macropinocytosis, DOX/PCT micelles were depolymerized in intercellular acidic and a reductive environment to release DOX rapidly to kill tumor cells. Additionally, DOX/PCT micelles had a better inhibitory effect on tumor growth than DOX/PAT micelles in in vivo antitumor activity studies. Therefore, pH/reduction dual sensitive PCT polymers have great potential to be used as repaid release nanocarriers for intercellular delivery of antitumor drugs.

Magneto-Activation and Magnetic Resonance Imaging of Natural Killer Cells Labeled with Magnetic Nanocomplexes for the Treatment of Solid Tumors

Natural killer (NK) cell-based immunotherapy has been considered a promising cell-based cancer treatment strategy with low side effects for early tumors and metastasis. However, the therapeutic efficacy is generally low in established solid tumors. Ex vivo activation of NK cells with exogenous cytokines is often essential but ineffective to generate high doses of functional NK cells for cancer treatment. Image-guided local delivery of NK cells is also suggested for the therapy. However, there is a lack of noninvasive tools for monitoring NK cells. Herein, magnetic nanocomplexes are fabricated with clinically available materials (hyaluronic acid, protamine, and ferumoxytol; HAPF) for labeling NK cells. The prepared HAPF-nanocomplexes effectively attach to the NK cells (HAPF-NK). An exogenous magnetic field application effectively achieves magneto-activation of NK cells, promoting the generation and secretion of lytic granules of NK cells. The magneto-activated HAPF-NK cells also allow an MR image-guided NK cell therapy to treat hepatocellular carcinoma (HCC) solid tumors via transcatheter intra-arterial infusion. Suppressed tumor growth after the treatment of IA infused magneto-activated NK cells demonstrated a potential enhanced therapeutic efficacy of image guided local delivery of magneto-activated HAPF-NK cells. Given the potential challenges of NK cell cancer immunotherapy against established solid tumors, the effective NK cell labeling with HAPF, magneto-activation, and MRI contrast effect of NK cells will be beneficial to enhance the NK cell-therapeutic efficacy in various cancers.

Targeted polymeric nanoparticle for anthracycline delivery in hypoxia-induced drug resistance in metastatic breast cancer cells

Poly lactic-co-glycolic acid (PLGA) nanoparticles are intensively studied nanocarriers in drug delivery because of their biodegradability and biochemical characteristics. Polyethylene glycol (PEG) coating for nanocarriers gives them long circulation time in blood and makes them invisible to the reticuloendothelial system. Breast cancer cells have greater uptake of hyaluronic acid compared to normal cells as it binds to their overexpressed CD44 receptors. Since hypoxia plays an important role in cancer metastasis; we formulated PEG-PLGA nanoparticles coated with hyaluronic acid as targeted delivery system for doxorubicin (DOX) using nanoprecipitation method, and characterized them for chemical composition, size, surface charge, shape, and encapsulation efficiency. Then we tested them in vitro on hypoxia-optimized metastatic breast cancer cells. The nanoparticles were spherical with an average size of about 106 ± 53 nm, a negative surface charge (-15 ± 3 mV), and high encapsulation efficiency (73.3 ± 4.1%). In vitro investigation with hypoxia-elevated CD44 MDA-MB-231 cells showed that hyaluronic acid-targeted nanoparticles maintained their efficacy despite hypoxia-induced drug resistance unlike free DOX and nontargeted nanoparticles. In conclusion, this study revealed a simple third generation nanoparticle formulation for targeted treatment of hypoxia-induced drug resistance in breast cancer metastatic cells. Further, optimization is needed including In vivo efficacy and nanoparticle-specific pharmacokinetic studies.

A Gelatin-Hyaluronic Acid Double Cross-Linked Hydrogel for Regulating the Growth and Dual Dimensional Cartilage Differentiation of Bone Marrow Mesenchymal Stem Cells

Owing to its unique physiochemical properties similar to the extracellular matrix (ECM), three-dimensional (3D) crosslinked hydrogels are widely studied materials for tissue engineering. In this study, to mimic the ECM microenvironment, a two-step covalent cross-linking with hyaluronic acid and gelatin was performed to form an interpenetrating polymer network structure. Gelatin as the first network greatly improved the mechanical strength of the hydrogels, while a hyaluronic acid network as the second network improved the tenacity and biological activity. Compared with a single network hydrogel, the interpenetrating hydrogel system can further regulate the mechanical properties of the hydrogel by adjusting the ratio of the two components, thereby changing the proliferation, activity, and direction of cartilage differentiation of bone marrow mesenchymal stem cells (BMSCs). Not only that, with two culture methods for BMSCs on the surface and 3D wrapped in the double cross-linked hydrogels, they exhibited their potential to induce BMSCs to cartilage differentiation under the condition of 3D encapsulation of BMSCs and contact with BMSCs on its surface. As a scaffold material for cartilage tissue engineering, this double cross-linked hydrogel demonstrated its high feasibility and applicability in delivering BMSCs in vivo and repairing defects.

One-pot fabrication of dual-redox sensitive, stabilized supramolecular nanocontainers for potential programmable drug release using a multifunctional cyclodextrin unit

Facile engineering of β-cyclodextrin (β-CD)-based supramolecular nanocontainers with simultaneous enhanced extracellular stability and efficient intracellular biosignals-triggered destabilization generally suffers from multistep synthesis and tedious purification process, thus remains a significant challenge for the scale-up production and clinical translation of β-CD-based supramolecular nanomedicine. To address these issues, we reported in this study a one-pot preparation of dual-redox sensitive, stabilized supramolecular nanocontainers for potential programmable drug release by self-crosslinking of a multifunctional β-CD unit that integrates a host cavity for oxidation-mediated reversible complexation with ferrocence (Fc) guest molecule and lipoic acids (LAs)-decorated primary and secondary faces for reversible in-situ crosslinking by the reducible disulfide links. The resulting doxorubicin (DOX)-loaded nanoparticles showed, on one hand, enhanced colloidal stability and high DOX loading capacity with a drug loading content (DLC) of approximately 11.3% due to the crosslinked structure, and on the other hand, a programmable destruction of the supramolecular micelles triggered by a simultaneous adoption of intracellular glutathione (GSH) and reactive oxygen species (ROS) toward a complete structural destruction for promoted drug release with enhanced therapeutic efficiency. Notably, an optimized DOX-loaded micelle formation, DOX@CL P1 showed greater cytotoxicity with an IC₅₀ of 2.94 ± 0.25 μg/mL than free DOX (6.00 ± 0.56 μg/mL) in Bel-7402 cancer liver cells, but a significantly reduced side effect relative to free DOX in L02 normal liver cells. In vivo animal study in Bel-7402 tumor-bearing BALB/c mice further confirmed prolonger elimination half-life time, efficient tumor accumulation, enhanced therapeutic efficiency and compromised systemic toxicity of this micelle construct. Therefore the multifunctional CD unit developed in this study offers an extremely straightforward and robust strategy with respect to dual-redox responsive, stabilized supramolecular nanocontainers with potential programmable controlled release properties for clinical translations.

Hyaluronic acid coating on the surface of curcumin-loaded ZIF-8 nanoparticles for improved breast cancer therapy: An in vitro and in vivo study

Despite developments in surgery and chemotherapy, effective treatment of breast cancer is still an urgent problem owing to recurrence and metastasis. By combining the advantages of curcumin (Cur), zeolitic imidazolate framework-8 nanoparticles (ZIF-8), and hyaluronic acid (HA) in breast cancer therapy, Cur-loaded and HA-coated ZIF-8 (Cur@ZIF-8@HA) were synthesized using a method based on the pH-dependent solubility of Cur and the electrostatic interactions between zinc ions and carboxyl groups of HA. Cur@ZIF-8 were also prepared as a control group. Comprehensive comparisons of the physicochemical properties and anticancer activities of Cur@ZIF-8@HA and Cur@ZIF-8 were conducted. The results indicated that the degradation of Cur during the synthesis of Cur@ZIF-8 was negligible. The obtained Cur@ZIF-8 and Cur@ZIF-8@HA were truncated cubes with hydrodynamic diameters of 174 and 217 nm, respectively. Cur@ZIF-8@HA possessed better stability during storage in different media, a slower drug release rate under neutral and acidic conditions, and a greater inhibitory effect on breast cancer than Cur@ZIF-8. For 4T1 cells, treatment using Cur@ZIF-8@HA induced more cellular uptake and higher cytotoxicity, accompanied by higher lactate dehydrogenase release, cell cycle arrest in G2/M and S phases, production of reactive oxygen species, and apoptosis. In 4T1 tumor-bearing mice models, Cur@ZIF-8@HA showed a stronger inhibitory effect on tumor growth and pulmonary metastasis. Therefore, Cur@ZIF-8@HA might hold great potential as an agent for the effective therapy of breast cancer.

Delivery Systems for Nucleic Acids and Proteins: Barriers, Cell Capture Pathways and Nanocarriers

Gene therapy has been used as a potential approach to address the diagnosis and treatment of genetic diseases and inherited disorders. In this line, non-viral systems have been exploited as promising alternatives for delivering therapeutic transgenes and proteins. In this review, we explored how biological barriers are effectively overcome by non-viral systems, usually nanoparticles, to reach an efficient delivery of cargoes. Furthermore, this review contributes to the understanding of several mechanisms of cellular internalization taken by nanoparticles. Because a critical factor for nanoparticles to do this relies on the ability to escape endosomes, researchers have dedicated much effort to address this issue using different nanocarriers. Here, we present an overview of the diversity of nanovehicles explored to reach an efficient and effective delivery of both nucleic acids and proteins. Finally, we introduced recent advances in the development of successful strategies to deliver cargoes.

The Use of Alternative Strategies for Enhanced Nanoparticle Delivery to Solid Tumors

Nanomaterial (NM) delivery to solid tumors has been the focus of intense research for over a decade. Classically, scientists have tried to improve NM delivery by employing passive or active targeting strategies, making use of the so-called enhanced permeability and retention (EPR) effect. This phenomenon is made possible due to the leaky tumor vasculature through which NMs can leave the bloodstream, traverse through the gaps in the endothelial lining of the vessels, and enter the tumor. Recent studies have shown that despite many efforts to employ the EPR effect, this process remains very poor. Furthermore, the role of the EPR effect has been called into question, where it has been suggested that NMs enter the tumor via active mechanisms and not through the endothelial gaps. In this review, we provide a short overview of the EPR and mechanisms to enhance it, after which we focus on alternative delivery strategies that do not solely rely on EPR in itself but can offer interesting pharmacological, physical, and biological solutions for enhanced delivery. We discuss the strengths and shortcomings of these different strategies and suggest combinatorial approaches as the ideal path forward.

Preparation and characterization of PEGylated liposomal Doxorubicin targeted with leptin-derived peptide and evaluation of their anti-tumor effects, in vitro and in vivo in mice bearing C26 colon carcinoma

Employing targeting ligands on the surface of liposomes has the great potential to improve therapeutic efficacy and decreases off-target effects of liposomal formulations. In the present study, a leptin-derived peptide (Lp31) was evaluated to optimize the therapeutic efficacy of PEGylated liposomal Doxorubicin (PLD, Caelyx®). Leptin is an appetite regulatory hormone that is secreted into the blood circulation by the adipose tissue and it functions via its over expressed receptors (Ob-R) in a wide variety of cancers. Lp31, as targeting ligand, was conjugated to Maleimide-PEG2000-DSPE and then post-inserted into Caelyx. The anti-tumor activity and therapeutic efficacy of leptin modified Caelyx were evaluated and compared with Caelyx. The in vitro experiments demonstrated enhanced cytotoxicity and cellular uptake of Lp31-targeted Caelyx in C26 cell line compared to Caelyx. In BALB/c mice bearing C-26 murine carcinoma, Lp31 modified Caelyx groups exhibited significantly higher doxorubicin concentration at tumor tissue. Furthermore, Lp31 modified Caelyx at the dose of 10 mg/kg resulted in significant tumor growth inhibition and enhanced survival time compared to Caelyx. According to these results, the novel Lp31-liposomal doxorubicin offers great promise for the treatment of colon cancer and merits further investigation.

Fibroblast activation protein-α-adaptive micelles deliver anti-cancer drugs and reprogram stroma fibrosis

Cancer-associated fibroblasts (CAFs) are the majority cell population of tumor stroma, and they not only play important roles in tumor growth and metastasis, but they also form a protective physical barrier for cancer cells. Herein, we designed a fibroblast activation protein-α (FAP-α)-adaptive polymeric micelle based on hyaluronic acid and curcumin conjugates. The polymeric micelle is composed of a CD44-targeting shell and a FAP-α-cleavable polyethylene glycol (PEG) coating. When FAP-α is encountered on the surface of CAFs in the tumor microenvironment, the PEG layer is released, hyaluronic acid is recovered on the surface of nanoparticles, and the nanoparticles effectively inhibit the growth of tumor cells and CAFs through CD44-mediated endocytosis. The FAP-α-adaptive polymeric micelle exhibited potent anti-cancer efficacy by enhancing CAF apoptosis and reducing collagen in tumor tissues. Collectively, FAP-α-adaptive nanoparticles may be a promising method for antitumor anticancer treatments via reprogramming of stroma fibrosis.

Uptake and in vitro anticancer activity of oleic acid delivered in nanocapsules stabilized by amphiphilic derivatives of hyaluronic acid and chitosan

The nanoemulsion-based delivery systems have gained particular attention due to effective encapsulation and protection of hydrophobic active compounds. However, several features like limited stability, cellular uptake or release of payloads still need to be addressed. We investigated the uptake of the nanocapsules based on the amphiphilic derivative of hyaluronate with oleic acid cores (oil-in-water nanoemulsion) and their anticancer activity in vitro. The core-shell nanocapsules exhibiting long term stability in dispersion showed an enhanced uptake by cancer cells and effectively killed them only if composed of hyaluronate-based shells and oleic acid cores - the anionic chitosan-based shells and/or corn oil cores were used for control experiments. We concluded that the nanocapsules stabilized by the amphiphilic derivative of hyaluronic acid may serve as very stable and efficient delivery systems for oil-soluble compounds without necessity of application of low molecular weight (co)surfactants. The in vitro studies indicated anticancer activity of such delivered oleic acid and crucial role of hyaluronate shell of the nanocapsules in its efficient delivery and enzyme-triggered disintegration inside cells. Corn oil was shown as a nutrient that can serve as an inert vehicle in the studied nanoemulsion that exhibit application potential in food, dietary supplement industry and medicine.

Dual-Mode Avocado-like All-Iron Nanoplatform for Enhanced T1/T2 MRI-Guided Cancer Theranostic Therapy

Development of T₁/T₂ dual-mode MRI contrast agents that can also treat cancer is an attractive prospect for personalized precision medicine. Unfortunately, conventional contrast agents can suffer from toxicity and lack any ability to treat cancer. An all-iron T₁/T₂ MR imaging agent with photothermal and drug delivery capability would overcome these issues. Here, an avocado-like Fe³⁺/Fe₂O₃ composed T₁-T₂ dual-mode contrast agent based on Fe-TA coordination network (CNMN) is developed. This material possesses suitable longitudinal and transverse relaxation coefficients. Moreover, the strong heat generation property of Fe-TA endows CNMN with the capability to act as a potent photothermal agent. Furthermore, CNMN can also act as an effective delivery platform for the chemotherapeutic drug doxorubicin (DOX) to achieve high effective chemo-photothermal combination therapy. The work demonstrates reliable T₁-T₂ MRI-guided chemo-photothermal therapy for safe and effective clinical application.

Acid-labile polysaccharide prodrug via lapatinib-sensitizing effect substantially prevented metastasis and postoperative recurrence of triple-negative breast cancer

Surgical resection and chemotherapy are routinely performed for triple-negative breast cancer (TNBC) because it is insensitive to endocrine therapy and molecular targeted therapy. Here, the optimal surface charge (-28 mV) and particle size (51 nm) enabled the acid-labile hyaluronic acid pullulan prodrug (HPP)-doxorubicin (Dox)/lapatinib (Lap) conjugate to circulate in the blood for a lengthy period of time and enhance the electron paramagnetic resonance effect, while the targeted molecule hyaluronic acid accelerated CD44 receptor-mediated 4T1 cell internalization. The inefficient anti-proliferation capability of Lap increased more than 10-fold after sensitization of Dox to metastatic 4T1 cells, while cellular uptake significantly increased, and cell viability dramatically decreased to nearly 20% of the free Dox group. Furthermore, HPP-Dox/Lap more effectively inhibited lateral mobility, vertical migration, and invasion ability of 4T1 cells. The ex vivo biodistribution of representative Dox indicated that Lap obviously facilitated the intratumoral infiltration and accumulation. The in vivo research revealed that there were overwhelming advantages in using HPP-Dox/Lap to inhibit tumor growth, progression, and lung metastasis even at a low dosage (1 mg kg-1), and it decreased postoperative recurrence and pulmonary metastatic nodules. Because of the excellent biosafety and visible therapeutic effect on the 4T1 metastasis and recurrence model, there is great potential value for HPP-Dox/Lap to be used to treat metastatic TNBC.

A novel kinetic model to describe the ultra-fast triggered release of thermosensitive liposomal drug delivery systems

Thermosensitive liposomes, as one of the stimuli-responsive drug delivery systems, receive growing attention, due to their ability to generate rapid and massive drug release in the heated area, and marginal release of contents in non-heated parts of the body. This typical triggered release behavior cannot be fitted adequately by most of the current mathematical kinetic models. The aim of this study was to establish the proper kinetic equation to describe the rapid release of drugs from trigger-sensitive drug delivery systems. We summarized all commonly used kinetic models mentioned in the literature and fitted the release data with these models, finding that only the Korsmeyer-Peppas and the Weibull models show acceptable fitting results. To better describe the release from thermosensitive liposomes with a size below 100 nm, we took Laplace pressure as a release-driving force and proposed a new equation that demonstrates improved fitting in liposomes ranging down to a size of 70 nm. Our new kinetic model shows desirable fitting, not only at the optimal temperature but also of releases within the whole release-temperature range, providing a useful kinetic model to describe release profiles of smaller nano-sized stimuli-responsive drug delivery systems.

Hyaluronic Acid-Based Theranostic Nanomedicines for Targeted Cancer Therapy

Hyaluronic acid (HA) is a natural mucopolysaccharide and has many useful advantages, including biocompatibility, non-immunogenicity, chemical versatility, non-toxicity, biodegradability, and high hydrophilicity. Numerous tumor cells overexpress several receptors that have a high binding affinity for HA, while these receptors are poorly expressed in normal body cells. HA-based drug delivery carriers can offer improved solubility and stability of anticancer drugs in biological environments and allow for the targeting of cancer treatments. Based on these benefits, HA has been widely investigated as a promising material for developing the advanced clinical cancer therapies in various formulations, including nanoparticles, micelles, liposomes, and hydrogels, combined with other materials. We describe various approaches and findings showing the feasibility of improvement in theragnosis probes through the application of HA.

Keratin-Poly(2-methacryloxyethyl phosphatidylcholine) Conjugate-Based Micelles as a Tumor Micro-Environment-Responsive Drug-Delivery System with Long Blood Circulation

Drug-loaded micelles with long circulation time in blood and stimuli-responsiveness under the tumor micro-environment can significantly enhance therapeutic efficacy. In this report, human hair keratin was extracted with a reduction method and then conjugated with zwitterionic poly(2-methacryloxyethyl phosphatidylcholine, MPC) via thiol chain transfer polymerization (thiol CTP). Subsequently, keratin-polyMPC conjugates (KPC) were prepared into micelles and loaded with doxorubicin (DOX) by self-assembly. These micelles exhibited pH, glutathione (GSH), and enzyme triple-responsiveness as well as charge reversibility under the tumor micro-environment. In addition, these micelles showed high toxicity against A549 cells while low toxicity to normal cells. In vivo anticancer efficacy results revealed that these micelles showed better therapeutic efficiency than free DOX. Furthermore, these carriers exhibited prolonged circulation time, good stability, and no hemolysis in blood. Based on the results, these drug delivery systems of micelles were proper candidates as drug carriers.

Meta-Analysis of Nanoparticle Delivery to Tumors Using a Physiologically Based Pharmacokinetic Modeling and Simulation Approach

Numerous studies have engineered nanoparticles with different physicochemical properties to enhance the delivery efficiency to solid tumors, yet the mean and median delivery efficiencies are only 1.48% and 0.70% of the injected dose (%ID), respectively, according to a study using a nonphysiologically based modeling approach based on published data from 2005 to 2015. In this study, we used physiologically based pharmacokinetic (PBPK) models to analyze 376 data sets covering a wide range of nanomedicines published from 2005 to 2018 and found mean and median delivery efficiencies at the last sampling time point of 2.23% and 0.76%ID, respectively. Also, the mean and median delivery efficiencies were 2.24% and 0.76%ID at 24 h and were decreased to 1.23% and 0.35%ID at 168 h, respectively, after intravenous administration. While these delivery efficiencies appear to be higher than previous findings, they are still quite low and represent a critical barrier in the clinical translation of nanomedicines. We explored the potential causes of this poor delivery efficiency using the more mechanistic PBPK perspective applied to a subset of gold nanoparticles and found that low delivery efficiency was associated with low distribution and permeability coefficients at the tumor site (P < 0.01). We also demonstrate how PBPK modeling and simulation can be used as an effective tool to investigate tumor delivery efficiency of nanomedicines.

LDH-stabilized ultrasmall iron oxide nanoparticles as a platform for hyaluronidase-promoted MR imaging and chemotherapy of tumors

Development of unique theranostic nanoplatforms for tumor imaging and therapy remains an active topic in current nanomedicine. Here, we designed a novel targeted theranostic nanoplatform for enhanced T1 -weighted magnetic resonance (MR) imaging-guided chemotherapy by constructing layered double hydroxide (LDH)-stabilized ultrasmall iron oxide (Fe3O4) nanoparticles with hyaluronic acid (HA) modified as targeting agents, and anticancer drug doxorubicin (DOX) loaded with a high loading efficiency. Methods: The structure and release property of LDH-Fe3O4-HA/DOX nanoplatforms were characterized systematically. B16 melanoma cells with CD44 receptors overexpressed were used as model cells to determine the biocompatibility, targeting capability, and therapeutic efficiency of nanoplatforms. For in vivo experiment, hyaluronidase (HAase) pretreatment was combined with nanoplatform administration to investigate the MR imaging and chemotherapeutic effect. Results: The LDH-Fe3O4-HA nanohybrids possess good colloidal stability and cytocompatibility, display an r1 relaxivity 10-fold higher than the pristine ultrasmall Fe3O4 (4.38 mM-1 s-1vs 0.42 mM-1 s-1), and could release drug in a pH-responsive manner. In vitro experiments demonstrate that LDH-Fe3O4-HA/DOX nanohybrids are able to specifically target B16 cells overexpressing CD44 receptors and effectively release DOX to nucleus. In vivo results show that with the pretreatment of tumor tissue by HAase to degrade the overexpressed HA in extra-cellular matrix, the designed nanoplatforms have a better tumor penetration for significantly enhanced MR imaging of tumors and tumor chemotherapy with low side effects. Conclusion: The designed LDH-Fe3O4-HA/DOX nanohybrids may be developed as a novel targeted theranostic nanoplatform for enhanced T1 -weighted MR imaging-guided chemotherapy of CD44 receptor-overexpressing tumors.

Enhanced anti-tumor and anti-metastasis therapy for triple negative breast cancer by CD44 receptor-targeted hybrid self-delivery micelles

Tumor growth and metastasis are multistep processes regulated by multiple signaling pathways. The successful treatment of cancer largely depends on the ability to inhibit metastatic process. Multiphase inhibition of metastasis is a promising approach. Here, we described a targeting delivery system which was constructed by mixing hyaluronic acid-d-α-tocopheryl succinate (HA-TOS, HT) and low molecular weight heparin-TOS (LMWH-TOS, LT) to form a stable hybrid micelle (HT-LT), encapsulating chemotherapeutic drug doxorubicin (DOX). The prepared HT-LT NPs was about 125 nm in diameter with high drug encapsulation rate and continuous drug release behavior. We confirmed that HT-LT NPs exhibited an effective targeting ability both in vitro and in vivo using a 4T1 model that was attributed to HA binding to CD44 receptors. In addition, HT-LT NPs acted on different phases of the invasion-metastasis cascade and inhibited tumor cell migration and invasion, thus inhibiting tumor metastasis. This combinatorial strategy provided an alternative approach for triple negative breast cancer therapy.

Emerging well-tailored nanoparticulate delivery system based on in situ regulation of the protein corona

The protein corona significantly changes the nanoparticle (NP) identity both physicochemically and biologically, and in situ regulation of specific plasma protein adsorption on NP surfaces has emerged as a promising strategy for disease-targeting therapy. In the past decade, great progress in protein corona regulation has been achieved via surface chemistry-based nanomedicine development. This review first outlines the latest advances in bio-nano interactions, with special attention to factors that influence the protein corona, including NP physicochemical properties, the biological environment and the duration time. Second, NP surface chemistry strategies designed to inhibit and regulate protein corona formation are highlighted, with special emphasis on albumin, transferrin, apolipoprotein (apo) E, vascular endothelial growth factor (VEGF) and retinol binding protein 4 (RBP4). Finally, the current techniques used to characterize the protein corona are briefly discussed.

A Strategy of Killing Three Birds with One Stone for Cancer Therapy through Regulating the Tumor Microenvironment by H2O2-Responsive Gene Delivery System

Constructing an efficient in vivo gene delivery system has always been extremely challenging. Herein, a highly efficient H₂O₂-responsive in vivo polycationic gene delivery system is developed for the first time. The efficient vector PLL-RT (i.e., polylysine grafted with p-tosyl-l-arginine) is used to mediate plasmid DNA (pDNA) delivery, and H₂O₂-responsive thioketal dipropanedioic acid-modified dextran (TDPAD) is used as a shielding system for effectively coating vector/pDNA polyplexes. The constructed gene delivery system exhibits a prolonged circulatory half-life in vivo and accelerates the accumulation of vector/DNA polyplexes in tumor tissue by the enhanced permeability and retention (EPR) effect. Moreover, this gene delivery system exhibits highly efficient and synergistic antitumor effects through a strategy of killing three birds with one stone. First, upon the arrival of TDPAD/PLL-RT/pDNA [abbreviated as T(PD)] at the tumor site by the EPR effect, TDPAD reacts with excess H₂O₂ in tumor tissue, contributing to the detachment of TDPAD, and PLL-RT then mediates the enhanced endocytosis of pDNA encoding shVEGF and significantly downregulates the expression of vascular endothelial growth factor (VEGF) in tumor tissue, exhibiting an outstanding antitumor effect. Second, the H₂O₂ consumption by TDPAD significantly decreases the H₂O₂ level in tumor tissue, which synergistically suppresses tumor growth. Third, small-molecule product mercaptopropionic acid, generated by the reaction of TDPAD with H₂O₂, can induce cancer cell apoptosis and exert pronounced antitumor efficacy. This polycationic gene delivery system shows negligible toxicity in vitro and in vivo. This strategy provides an ideal platform for constructing an efficient in vivo gene delivery system and has bright prospects for cancer therapy.

Dually Active Targeting Nanomedicines Based on a Direct Conjugate of Two Purely Natural Ligands for Potent Chemotherapy of Ovarian Tumors

Actively targeted nanomedicines have promised to revolutionize cancer treatment; however, their clinical translation has been limited by either low targetability, use of unsafe materials, or tedious fabrication. Here, we developed CD44 and folate receptor (FR) dually targeted nanoparticulate doxorubicin (HA/FA-NP-DOX) based on a direct conjugate of two purely natural ligands, hyaluronic acid and folic acid (FA), for safe, highly specific, and potent treatment of ovarian tumors in vivo. HA/FA-NP-DOX had a small size and high DOX loading, wherein the particle size decreased from 115, 93, to 89 nm with increasing degree of substitution of FA from 6.4, 8.5, to 11.1, while increased from 80, 93, to 103 nm with increasing DOX loading from 15.0, 23.1, to 31.4 wt %. Interestingly, HA/FA-NP-DOX exhibited excellent lyophilization redispersibility and long-term storage stability with negligible drug leakage while it released 91% of DOX in 48 h at pH 5.0. Cellular studies corroborated that HA/FA-NP-DOX possessed high selectivity to both CD44 and FR, resulting in strong killing of CD44- and FR-positive SKOV-3 ovarian cancer cells while low toxicity against CD44- and FR-negative L929 fibroblast cells. In vivo studies revealed a long elimination half-life of 5.6 h, an elevated tumor accumulation of 12.0% ID/g, and an effective inhibition of the SKOV-3 ovarian tumor for HA/FA-NP-DOX, leading to significant survival benefits over free DOX·HCl and phosphate-buffered saline controls. These dually targeted nanomedicines are simple and safe, providing a potentially translatable treatment for CD44- and FR-positive malignancies.

Desirable PEGylation for improving tumor selectivity of hyaluronic acid-based nanoparticles via low hepatic captured, long circulation times and CD44 receptor-mediated tumor targeting

PEG coating was regarded as one effective method to improve the tumor-targeting efficiency of hyaluronic acid-based nanoparticles (HBN). However, the research of interaction between PEG coating and different receptors such as stabilin-2 and CD44 was limited. Herein, we synthesized a series of PEGylated hyaluronic acid with Curcumin (PHCs) to evaluate the role of PEG coating density in the interaction between HA and its receptors, which influenced tissues targeting activity, pharmacokinetic profiles and therapeutic efficacy of HBN. Compared with other counterparts, PHC HBN with about 5% PEG coating density preferably accumulated in the tumor mass, rather than in the liver, and hold desirable anti-cancer effect. These results indicated that to obtain optimized anticancer effect of HBN, the cellular uptake efficiency between different types of the cells should be carefully balanced by different PEG densities.

A Safe-by-Design Strategy towards Safer Nanomaterials in Nanomedicines

The marriage of nanotechnology and medicine offers new opportunities to fight against human diseases. Benefiting from their unique optical, thermal, magnetic, or redox properties, a wide range of nanomaterials have shown potential in applications such as diagnosis, drug delivery, or tissue repair and regeneration. Despite the considerable success achieved over the past decades, the newly emerging nanomedicines still suffer from an incomplete understanding of their safety risks, and of the relationships between their physicochemical characteristics and safety profiles. Herein, the most important categories of nanomaterials with clinical potential and their toxicological mechanisms are summarized, and then, based on this available information, an overview of the principles in developing safe-by-design nanomaterials for medical applications and of the recent progress in this field is provided. These principles may serve as a starting point to guide the development of more effective safe-by-design strategies and to help identify the major knowledge and skill gaps.

pH and redox dual-responsive nanoparticles based on disulfide-containing poly(β-amino ester) for combining chemotherapy and COX-2 inhibitor to overcome drug resistance in breast cancer

Background

Multidrug resistance (MDR) generally leads to breast cancer treatment failure. The most common mechanism of MDR is the overexpression of ATP-binding cassette (ABC) efflux transporters such as P-glycoprotein (P-gp) that reduce the intracellular accumulation of various chemotherapeutic agents. Celecoxib (CXB), a selective COX-2 inhibitor, can dramatically enhance the cytotoxicity of doxorubicin (DOX) in breast cancer cells overexpressing P-gp. Thus it can be seen that the combination of DOX and CXB maybe obtain synergistic effects against breast cancer by overcoming drug resistance.

Results

In this study, we designed a pH and redox dual-responsive nanocarrier system to combine synergistic effects of DOX and CXB against drug resistant breast cancer. This nanocarrier system denoted as HPPDC nanoparticles showed good in vitro stability and significantly accelerated drug releases under the acidic and redox conditions. In drug-resistant human breast cancer MCF-7/ADR cells, HPPDC nanoparticles significantly enhanced the cellular uptake of DOX through the endocytosis mediated by CD44/HA specific binding and the down-regulated P-gp expression induced by COX-2 inhibition, and thus notably increased the cytotoxicity and apoptosis-inducing activity of DOX. In MCF-7/ADR tumor-bearing nude mice, HPPDC nanoparticles showed excellent tumor-targeting ability, remarkably enhanced tumor chemosensitivity and reduced COX-2 and P-gp expressions in tumor tissues.

Conclusion

All results demonstrated that HPPDC nanoparticles can efficiently overcome drug resistance in breast cancer both in vitro and in vivo by combining chemotherapy and COX-2 inhibitor. In a summary, HPPDC nanoparticles show a great potential for combination treatment of drug resistant breast cancer.