Efficient Delivery of DOX to Nuclei of Hepatic Carcinoma Cells in the Subcutaneous Tumor Model Using pH-Sensitive Pullulan-DOX Conjugates

Recent advances in pH/enzyme-responsive polysaccharide-small-molecule drug conjugates as nanotherapeutics

Now-a-days, the polysaccharides are extensively employed for the delivery of small-molecule drugs ascribed to their excellent biocompatibility, biodegradability and modifiability. An array of drug molecules is often chemically conjugated with different polysaccharides to augment their bio-performances. As compared to their therapeutic precursors, these conjugates could typically demonstrate an improved intrinsic solubility, stability, bioavailability and pharmacokinetic profiles of the drugs. In current years, various stimuli-responsive particularly pH and enzyme-sensitive linkers or pendants are also exploited to integrate the drug molecules into the polysaccharide backbone. The resulting conjugates could experience a rapid molecular conformational change upon exposure to the microenvironmental pH and enzyme changes of the diseased states, triggering the release of the bioactive cargos at the targeted sites and eventually minimize the systemic side effects. Herein, the recent advances in pH and enzyme -responsive polysaccharide-drug conjugates and their therapeutic benefits are systematically reviewed, following a brief description on the conjugation chemistry of the polysaccharides and drug molecules. The challenges and future perspectives of these conjugates are also precisely discussed.

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.

Intelligent poly(l-histidine)-based nanovehicles for controlled drug delivery

Stimuli-responsive drug delivery systems based on polymeric nanovehicles are among the most promising treatment regimens for malignant cancers. Such intelligent systems that release payloads in response to the physiological characteristics of tumor sites have several advantages over conventional drug carriers, offering, in particular, enhanced therapeutic effects and decreased toxicity. The tumor microenvironment (TME) is acidic, suggesting the potential of pH-responsive nanovehicles for enhancing treatment specificity and efficacy. The synthetic polypeptide poly(l-histidine) (PLH) is an appropriate candidate for the preparation of pH-responsive nanovehicles because the pK_a of PLH (approximately 6.0) is close to the pH of the acidic TME. In addition, the pendent imidazole rings of PLH yield pH-dependent hydrophobic-to-hydrophilic phase transitions in the acidic TME, triggering the destabilization of nanovehicles and the subsequent release of encapsulated chemotherapeutic agents. Herein, we highlight the state-of-the-art design and construction of pH-responsive nanovehicles based on PLH and discuss the future challenges and perspectives of this fascinating biomaterial for targeted cancer treatment and "benchtop-to-clinic" translation.

Simple Formation of Cancer Drug-Containing Self-Assembled Hydrogels with Temperature and pH-Responsive Release

The purpose of a drug delivery system is to efficiently deliver drugs to a desired target, while simultaneously reducing the side effects caused by these drugs and maximizing their efficacy. However, in the manufacture of a drug delivery system, it is difficult to control the amount of drug encapsulation. In this study, we developed a simple formation process of self-assembled hydrogels that made it easier to package the desired amount of anticancer drugs. A self-assembled hydrogel was prepared by simply mixing transferrin, dithiothreitol, and an anticancer drug in a salt solvent. The structural conditions of the hydrogel were determined in order to control the concentration of the transferrin protein, dithiothreitol, and salt in the solvent. The self-assembled hydrogels contained the desired amount of anticancer drugs. With this system, changes in pH and temperature control the release rate and the release ratio of anticancer drugs. The cytotoxicity of the drug-loaded hydrogel was evaluated, which showed that 80% of the treated cells had been killed following 48 h of incubation.

Fabrication of Versatile Hollow Metal-Organic Framework Nanoplatforms for Folate-Targeted and Combined Cancer Imaging and Therapy

Metal-organic frameworks (MOFs) have received extensive attention in the field of biomedicine, particularly serving as multifunctional theranostic nanoplatforms by integrating chemodrugs, imaging agents, and targeting agents. Herein, we report a facile strategy for the fabrication of a hollow and monodisperse MOF (denoted hMIL-88B(Fe)@ZIF-8) consisting of ZIF-8 nanoparticles loaded on the external shell of hollow MIL-88B(Fe). In particular, the hybrid hollow MOF was constructed by partially etching spindlelike MIL-88B(Fe) nanoparticles with 2-methylimidazole in the presence of zinc ions. The obtained hMIL-88B(Fe)@ZIF-8 was then used as a drug/cargo delivery vehicle for loading doxorubicin (DOX), manganese oxide (MnO_x) nanoparticles, and folic acid (FA), forming a multifunctional nanoplatform (denoted hM@ZMDF). Importantly, the resulting hM@ZMDF exhibited a specific targeting property for the FA receptor-overexpressed cancer cells (MCF-7 and HepG-2 cells) and then it unloaded DOX and Fe³⁺ in the tumor microenvironment. Consequently, DOX played dual roles as a chemotherapeutic drug and a fluorescent imaging agent. Also, the released Fe³⁺ could mediate the Fenton reaction and intracellularly generate toxic hydroxyl radicals in the presence of high glutathione in cancer cells. In addition, MnO_x nanoparticles could participate in magnetic resonance imaging. Therefore, the versatile hM@ZMDF nanoplatforms have great potential for smart cancer therapy.

Recent Advances in Asialoglycoprotein Receptor and Glycyrrhetinic Acid Receptor-Mediated and/or pH-Responsive Hepatocellular Carcinoma- Targeted Drug Delivery

BACKGROUND

Hepatocellular carcinoma (HCC) seriously affects human health, especially, it easily develops multi-drug resistance (MDR) which results in treatment failure. There is an urgent need to develop highly effective and low-toxicity therapeutic agents to treat HCC and to overcome its MDR. Targeted drug delivery systems (DDS) for cancer therapy, including nanoparticles, lipids, micelles and liposomes, have been studied for decades. Recently, more attention has been paid to multifunctional DDS containing various ligands such as polymer moieties, targeting moieties, and acid-labile linkages. The polymer moieties such as poly(ethylene glycol) (PEG), chitosan (CTS), hyaluronic acid, pullulan, poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO) protect DDS from degradation. Asialoglycoprotein receptor (ASGPR) and glycyrrhetinic acid receptor (GAR) are most often used as the targeting moieties, which are overexpressed on hepatocytes. Acid-labile linkage, catering for the pH difference between tumor cells and normal tissue, has been utilized to release drugs at tumor tissue.

OBJECTIVES

This review provides a summary of the recent progress in ASGPR and GAR-mediated and/or pH-responsive HCC-targeted drug delivery.

CONCLUSION

The multifunctional DDS may prolong systemic circulation, continuously release drugs, increase the accumulation of drugs at the targeted site, enhance the anticancer effect, and reduce side effects both in vitro and in vivo. But it is rarely used to investigate MDR of HCC; therefore, it needs to be further studied before going into clinical trials.

Enzyme-Responsive Biopolymeric Nanogel Fibers by Extrusion: Engineering of High-Surface-Area Hydrogels and Application in Bacterial Enzyme Detection

The fabrication of covalently cross-linked high-surface-area biopolymeric nanogel fibers by nanopore extrusion is reported for the first time. The biopolymer pullulan was functionalized with tert-butyl acetoacetate via a transesterification reaction to synthesize the water-soluble ketone-rich precursor pullulan acetoacetate (PUAA). PUAA and carbonic dihydrazide (CDH) as cross-linker were extruded through anodic aluminum oxide (AAO) nanoporous membranes, which possessed an average pore diameter of 61 ± 2 nm. By changing the concentration of PUAA, the flow rate, and extrusion time, the step polymerization cross-linking reaction was controlled so that the polymer can be extruded gradually during cross-linking through the membrane, avoiding the formation of macroscopic bulk hydrogels and rupture of the AAO membrane. Fibers with diameters on the order of 250 nm were obtained. This approach was also expanded to functionalized PUAA derivatives together with the fluorogenic substrate 4-methylumbelliferyl-β-d-glucuronide MUGlcU in (PUAA-MUGlcU), which exhibited a mean equilibrium swelling ratio of 5.7 and 9.0 in Milli-Q water and in phosphate-buffered saline, respectively. β-Glucuronidase was sensitively detected via fluorescence of 4-methylumbelliferone, which was liberated in the enzymatic hydrolysis reaction of PUAA-MUGlcU. Compared to hydrogel slabs, the rate of the hydrolysis was >20% higher in the nanogel fibers, facilitating the rapid detection of β-glucuronidase-producing Escherichia coli (E. coli Mach1-T1). Nanopore extruded nanogel fibers are therefore considered a viable approach to enhance the functionality of hydrogels in surface-dominated processes.

Pullulan based stimuli responsive and sub cellular targeted nanoplatforms for biomedical application: Synthesis, nanoformulations and toxicological perspective

With growing interest in polymers of natural origin, innumerable polysaccharides have gained attention for their biomedical application. Pullulan, one of the FDA approved nutraceuticals, possesses multiple unique properties which make them highly advantageous for biomedical applications. This present review encompasses the sources, production, properties and applications of pullulan. It highlights various pullulan based stimuli-responsive systems (temperature, pH, ultrasound, magnetic), subcellular targeted systems (mitochondria, Golgi apparatus/endoplasmic reticulum, lysosome, endosome), lipid-vesicular systems (solid-lipid nanoparticles, liposomes), polymeric nanofibres, micelles, inorganic (SPIONs, gold and silver nanoparticles), carbon-based nanoplatforms (carbon nanotubes, fullerenes, nanodiamonds) and quantum dots. This article also gives insight into different biomedical, therapeutic and diagnostic applications of pullulan viz., imaging, tumor targeting, stem cell therapy, gene therapy, vaccine delivery, cosmetic applications, protein delivery, tissue engineering, photodynamic therapy and chaperone-like activities. The review also includes the toxicological profile of pullulan which is helpful for the development of suitable delivery systems for clinical applications.

Chiral Active β-Glucan Nanoparticles for Synergistic Delivery of Doxorubicin and Immune Potentiation

Background

β-glucans are chiral polysaccharides with well-defined immunological properties and supramolecular wrapping ability of its chiral feature. However, the exploitation of chiral properties of these nanoparticles in drug delivery systems was seldom conducted.

Methods

β-glucan molecules with different chain lengths were extracted from yeast Saccharomyces cerevisiae and thereafter modified. In a conformation transition process, these β-glucan molecules were then self-assembled with anti-cancer drug doxorubicin into nanoparticles to construct drug delivery systems. The chiral interactions between the drug and carriers were revealed by circular dichroism spectra, ultraviolet and visible spectrum, fourier transform infrared spectroscopy, dynamic light scattering and transmission electron microscope. The immune-potentiation properties of modified β-glucan nanoparticles were evaluated by analysis of the mRNA expression in RAW264.7 cell model. Further, the antitumor efficacy of the nanoparticles against the human breast cancer were studied in MCF-7 cell model by cellular uptake and cytotoxicity experiments.

Results

β-glucan nanoparticles can activate macrophages to produce immune enhancing cytokines (IL-1β, IL-6, TNF-α, IFN-γ). A special chirality of the carriers in diameter of 50~160 nm can also associate with higher drug loading ability of 13.9% ~38.2% and pH-sensitive release with a change of pH from 7.4 to 5.0. Cellular uptake and cytotoxicity experiments also prove that the chiral-active β-glucan nanoparticles can be used in anti-cancer nanomedicine.

Conclusion

This work demonstrates that β-glucans nanoparticles with special chiral feature which leading to strong immunopotentiation ability and high drug loading efficiency can be developed as a novel type of nanomedicine for anti-cancer treatment.

Ultrasound Combined with Core Cross-Linked Nanosystem for Enhancing Penetration of Doxorubicin Prodrug/Beta-Lapachone into Tumors

BACKGROUND

Nanosized drug delivery systems (NDDSs) have shown excellent prospects in tumor therapy. However, insufficient penetration of NDDSs has significantly impeded their development due to physiological instability and low passive penetration efficiency.

METHODS

Herein, we prepared a core cross-linked pullulan-modified nanosized system, fabricated by visible-light-induced diselenide bond cross-linked method for transporting β-Lapachone and doxorubicin prodrug (boronate-DOX, BDOX), to improve the physiological stability of the NDDSs for efficient passive accumulation in tumor blood vessels (β-Lapachone/BDOX-CCS). Additionally, ultrasound (US) was utilized to transfer β-Lapachone/BDOX-CCS around the tumor vessel in a relay style to penetrate the tumor interstitium. Subsequently, β-Lapachone enhanced ROS levels by overexpressing NQO1, resulting in the transformation of BDOX into DOX. DOX, together with abundant levels of ROS, achieved synergistic tumor therapy.

RESULTS

In vivo experiments demonstrated that ultrasound (US) + cross-linked nanosized drug delivery systems (β-Lapachone/BDOX-CCS) group showed ten times higher DOX accumulation in the tumor interstitium than the non-cross-linked (β-Lapachone/BDOX-NCS) group.

CONCLUSION

Thus, this strategy could be a promising method to achieve deep penetration of NDDSs into the tumor.

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 redox-sensitive core-crosslinked nanosystem combined with ultrasound for enhanced deep penetration of nanodiamonds into tumors

Nanodiamonds (NDs) as drug delivery vehicles are of great significance in anticancer therapy through enhancing drug retention. However, the major barrier to clinical application of NDs is insufficient tumor penetration owing to their strong aggregation and low passive penetration efficiency. Herein, the core-crosslinked pullulan carrier, assembled using the visible light-induced diselenide (Se-Se) bond crosslinking method for encapsulating nanodiamonds-doxorubicin (NDX), is proposed to improve monodispersity. Furthermore, the core-crosslinked diselenide bond provides the nanosystem with redox-responsive capability and improved structural stability in a physiological environment, which prevents premature drug leakage and achieves tumor site-specific controlled release. What's more, ultrasound (US) is utilized to promote nanosystem intratumoral penetration via enlarged tumor vascular endothelium cell gaps. As expected, the nanosystem combined with ultrasound can enhance anti-tumor efficacy with deep penetration and excellent retention performance in a HepG2 xenograft mouse model. This study highlights the ability of the integrated therapeutic paradigm to overcome the limitation of nanodiamonds and the potential for further application in cancer therapy.

Polydopamine-doped virus-like mesoporous silica coated reduced graphene oxide nanosheets for chemo-photothermal synergetic therapy

Multifunctional nanocarriers have been widely accepted and utilized for biomedical applications, because of their structural regularity, convenient post-modification and controllable structure and morphology. Herein, we reported polydopamine-doped virus-like mesoporous silica coated reduced graphene oxide nanosheets (rGO@PVMSNs) nanocomposites by a facile oil–water biphase stratification method. The synthesized rGO@PVMSNs nanocomposites performed excellent biocompatibility and photothermal performance. They could be employed as photoacoustic imaging contrast in vivo. Furthermore, the rGO@PVMSNs nanocarriers were used for loading the antitumor drug doxorubicin (DOX), the rGO@PVMSNs@DOX nanocomposites were also demonstrated to be with high inhibition of HepG2 cancer cells, especially with the help of near-infrared irradiation, which were more efficient than single chemotherapy or photothermal therapy. The rGO@PVMSNs@DOX nanocomposites of this work could be used as photoacoustic imaging and chemo-photothermal synergetic therapy agents, which show a new perspective for clinical tumor diagnosis and therapy.

Extracellular pH-manipulated in situ reconfiguration of aptamer functionalized DNA monomer enables specifically improved affinity, detection and drug delivery

Aptamers are promising in cancer diagnosis and therapy, but their poor affinity under physiological conditions is a challenge. In view of the acidic microenvironment of solid tumors, we herein developed an extracellular pH-manipulated multivalent approach to exclusively improve the affinity to target cells at physiological temperature. Specifically, an aptamer based DNA monomer (AptDM) with split i-motif fragments overhanging was rationally designed, it possessed pH-responsiveness and doxorubicin loading capacity. At neutral pH, AptDMs existed as well dispersed small units, showing weakly undesired binding and internalization. In acidic extracellular conditions, AptDMs tended to crosslink of each other into multivalent DNA assemblies (MDAs) via formation of an intermolecular i-motif structure. Due to the multivalent effect, the resulting MDAs showed greatly enhanced affinity (K_d = 9.96 ± 1.06 nM) and stable binding ability at 37 °C, thus allowing highly sensitive diagnosis, efficient drug delivery, and improved inhibition to target tumor cells, but decreased cytotoxicity to nontarget cells. It is believed that this multivalent approach may boost the development of novel aptamer functionalized nanodevices for clinical validation.

Zwitterionic Polymer Micelles with Dual Conjugation of Doxorubicin and Curcumin: Synergistically Enhanced Efficacy against Multidrug-Resistant Tumor Cells

This paper reports a novel redox-sensitive micellar system for the co-delivery of doxorubicin (Dox) and a chemosensitizer (curcumin, Cur) to overcome the multidrug resistance (MDR) in cancer cells. Dox and Cur were co-conjugated onto a zwitterionic polymer, poly(carboxybetaine) (pCB), to form Cur-pCB-Dox that self-assembled into stable micelles (164.2 ± 4.8 nm). Single-drug conjugates (pCB-Dox and pCB-Cur) were prepared for comparisons. Compared to the high half-maximal inhibitory concentration (IC₅₀) of Dox (437.2 μg/mL), the IC₅₀ value of pCB-Dox (14.1 μg/mL) was only 1/33 that of Dox. Confocal laser scanning microscopy and flow cytometry revealed the greatly enhanced cell uptake of the conjugate due to the enhanced permeability and retention effect of tumor cells on the micellar conjugate. Co-delivery of pCB-Dox with pCB-Cur further reduced the IC₅₀ value by 37% (8.9 μg/mL). More importantly, Cur-pCB-Dox exhibited the strongest cytotoxicity against MCF-7/Adr cells (IC₅₀, 5.87 μg/mL) because the co-delivered Dox and Cur on one carrier specifically transported into the same cells, which inhibited the efflux of Dox by Cur, led to a higher intracellular Dox concentration and made the drugs exert synergistic effects at the targeting regions. The results proved the zwitterionic micelles as promising drug co-delivery vehicles for fighting against MDR.

Stimuli-responsive release and efficient siRNA delivery in non-small cell lung cancer by a poly(l-histidine)-based multifunctional nanoplatform

Small interfering RNA (siRNA) has extensive potential for the treatment of non-small cell lung cancer (NSCLC). While both cationic lipids and polymers have demonstrated promise to facilitate siRNA encapsulation, they can also hamper cytosolic siRNA release and induce severe cytotoxicity. To address these issues, a unique polymer hybrid nanoparticle (NP) nanoplatform was developed for multistage siRNA delivery based on both pH-responsive and endo/lysosomal escape characteristics, which was formed via a combination of an electrostatic interactions between the copolymer methoxy poly(ethylene glycol)-poly(l-histidine)-poly(sulfadimethoxine) (mPEG-PHis-PSD, shortened to PHD), dendritic poly-l-lysine (PLL) and PLK1 siRNA (shortened to siPLK1). The biological composition of the proton sponge effect polymer of the PHis chain, which was in position to make efficient endo/lysosomal escape, and the pH-responsive polymer of the PSD fragment, which could accelerate the release of siPLK1. In the present study, the NP illustrated excellent physiochemical properties and rapid endo/lysosomal escape in vitro. Besides this, compared with the PD/PLL/siRNA formulation, the PHD/PLL/siRNA NP indicated higher cellular uptake, and higher cell cytotoxicity in vitro. The in vivo results demonstrated that the PHD/PLL/siRNA NP exhibited the strongest tumor growth inhibition rate and ideal safety compared with the control and other siPLK1-treated formulations, which can be mainly attributed to pH-induced instantaneous dissociation and efficient endo/lysosomal escape arising from the PHD copolymer. Consequently, the above evidence indicates that the PHD/PLL/siRNA NP is a favorable gene delivery system and provides a potential strategy for siRNA delivery.

Self-Propelled Gemini-like LMWH-Scaffold Nanodrugs for Overall Tumor Microenvironment Manipulation via Macrophage Reprogramming and Vessel Normalization

Angiogenesis is the hallmark of melanoma that nurtures the tumor microenvironment (TME) for rapid tumor progression. Vessel normalization could benefit melanoma treatment through TME reconstruction, while its limited duration and extent are still the drag. Herein, two kinds of look-like nanodrugs, called Gemini-like nanodrugs (GLnano), were constructed separately with the same scaffold of antiangiogenic low molecular weight heparin (LMWH) and mixed upon administration in vivo. For one, doxorubicin (DOX) was encapsulated into LMWH-chrysin nanodrug (LCY) with DSPE-PEG-anisamide decoration (D-LCA nanodrugs) for active targeting and direct cell killing toward melanoma cells. For another, matrix metalloproteinases (MMPs)-sensitive peptide was conjugated to LMWH to encapsulate celecoxib (Cel) (C-Lpep nanodrugs), disassembling in TME by MMPs and releasing Cel for M2-to-M1 reprogramming of tumor-associated macrophages. Our results showed that GLnano could remarkably elongate the vessel normalization window up to 12 days with the highest pericyte coverage of nearly 75%, compared to only 4 days by LCY monotherapy. Furthermore, GLnano could spontaneously form the "treatment-delivery" loop to promote nanodrugs toward deep tumor regions, leading to a potent tumor inhibition, metastasis prevention, and overall TME improvements.

Multifunctional adenine-functionalized supramolecular micelles for highly selective and effective cancer chemotherapy

Adenine-functionalized supramolecular micelles are rapidly endocytosed by cancer cells and enable selective induction of tumor cell death, without harming normal cells.

Recent advances of nanomedicines for liver cancer therapy

This review highlights recent advancements in nanomedicines for liver cancer therapy.

Enzyme-Catalytic Self-Triggered Release of Drugs from a Nanosystem for Efficient Delivery to Nuclei of Tumor Cells

Stimulus-responsive drug delivery nanosystems (DDSs) are of great significance in improving cancer therapy for intelligent control over drug release. However, among them, many DDSs are unable to realize rapid and sufficient drug release because most internal stimulants might be consumed during the release process. To address the plight, an abundant supply of stimulants is highly desirable. Herein, a core crosslinked pullulan-di-(4,1-hydroxybenzylene)diselenide nanosystem, which could generate abundant exogenous-stimulant reactive oxygen species (ROS) via tumor-specific NAD(P)H:quinone oxidoreductase-1 (NQO1) catalysis, was constructed by the encapsulation of β-lapachone. The enzyme-catalytic-generated ROS induced self-triggered cascade amplification release of loaded doxorubicin (DOX) in the tumor cells, thus achieving efficient delivery of DOX to the nuclei of tumor cells by breaking the diselenide bond of the nanosystem. As a result, the antitumor effect of this nanosystem was significantly improved in the HepG2 xenograft model. In general, this study offers a new paradigm for utilizing the interaction between the loaded agent and carrier in the tumor cells to obtain self-triggered drug release in the design of DDSs for enhanced cancer therapy.

Polymeric nanoparticles as carrier for targeted and controlled delivery of anticancer agents

In recent decades, many novel methods by using nanoparticles (NPs) have been investigated for diagnosis, drug delivery and treatment of cancer. Accordingly, the potential of NPs as carriers is very significant for the delivery of anticancer drugs, because cancer treatment with NPs has led to the improvement of some of the drug delivery limitations such as low blood circulation time and bioavailability, lack of water solubility, drug adverse effect. In addition, the NPs protect drugs against enzymatic degradation and can lead to the targeted and/or controlled release of the drug. The present review focuses on the potential of NPs that can help the targeted and/or controlled delivery of anticancer agents for cancer therapy.

Ultrasound-Enhanced Delivery of Doxorubicin-Loaded Nanodiamonds from Pullulan-all-trans-Retinal Nanoparticles for Effective Cancer Therapy

Nanodiamond as a drug carrier is of great significance in improving cancer therapy by overcoming chemoresistance. However, its clinical application is severely limited because of insufficient tumor vascular penetration. To address this limitation, pullulan-all-trans-retinal (pullulan-ATR) self-assembled nanoparticles were prepared as nanocarriers, which encapsulated doxorubicin-loaded nanodiamonds, to construct a core-shell structured coloading nanosystem. The obtained composite nanoparticles show a homogeneous size distribution with good dispersity and pH sensitivity. Furthermore, ultrasound was utilized to promote the intratumoral penetration of these nanoparticles. As a result, the intracellular retention of DOX was efficiently enhanced, and DOX in the tumor tissue reached 17.3% of the injected dosage. The antitumor effect of this combined strategy was remarkably improved in both the DOX-sensitive HepG2 and DOX-resistant HepG2/ADR tumor models in vivo. This new strategy might serve as a powerful method to address the limitation of nanodiamonds and provide innovative ideas for the application of nanoparticles in clinical cancer therapy.

Size-controllable dual drug-loaded silk fibroin nanospheres through a facile formation process

Paclitaxel/doxorubicin-loaded silk fibroin nanospheres were prepared through a facile and green method and showed a synergistic effect on the anti-proliferative activity.

Acid-active supramolecular anticancer nanoparticles based on cyclodextrin polyrotaxanes damaging both mitochondria and nuclei of tumor cells

Acid-active supramolecular theranostics based on cyclodextrin polyrotaxanes for enhanced cancer therapy.

Shear-responsive injectable supramolecular hydrogel releasing doxorubicin loaded micelles with pH-sensitivity for local tumor chemotherapy

In this study, glycol chitosan-Pluronic F127 conjugate (GC-PF127), produced by an amidation reaction between terminal-carboxylated PF127 and glycol chitosan (GC), was used to prepare doxorubicin (DOX)-loaded micelles. The DOX/GC-PF127 micelles produced at optimal conditions had sizes of about 150nm and pH-sensitive surface charges. DOX/GC-PF127 hydrogel formed after addition of α-cyclodextrin into DOX/GC-PF127 micelle solution. The hydrogel had good shear-responsive, injectable and rapid recovery properties. In vitro release experiment confirmed that the hydrogel could sustainedly release DOX/GC-PF127 micelles via the dissociation of the hydrogel. After peritumoral injection into H22 tumor-bearing mice, the hydrogel could greatly increase DOX accumulation in tumor tissue and synchronously avoid DOX accumulation in normal tissues including heart. At similar total DOX dose administrated, the tumors of free DOX treatment group grew slowly after thrice intravenous injections, the tumors of the micelle group did not grow after twice intravenous injections, and the tumors of the hydrogel group disappeared almost after once peritumoral injection. This study demonstrates that injectable DOX/GC-PF127 hydrogel, which can sustainedly release DOX-loaded micelles with tumor-targeting function, is a promising system for local tumor chemotherapy.

Nanotechnology in Glycomics: Applications in Diagnostics, Therapy, Imaging, and Separation Processes

This review comprehensively covers the most recent achievements (from 2013) in the successful integration of nanomaterials in the field of glycomics. The first part of the paper addresses the beneficial properties of nanomaterials for the construction of biosensors, bioanalytical devices, and protocols for the detection of various analytes, including viruses and whole cells, together with their key characteristics. The second part of the review focuses on the application of nanomaterials integrated with glycans for various biomedical applications, that is, vaccines against viral and bacterial infections and cancer cells, as therapeutic agents, for in vivo imaging and nuclear magnetic resonance imaging, and for selective drug delivery. The final part of the review describes various ways in which glycan enrichment can be effectively done using nanomaterials, molecularly imprinted polymers with polymer thickness controlled at the nanoscale, with a subsequent analysis of glycans by mass spectrometry. A short section describing an active glycoprofiling by microengines (microrockets) is covered as well.

Non-Isocyanate Polyurethane Soft Nanoparticles Obtained by Surfactant-Assisted Interfacial Polymerization

Polyurethanes (PUs) are considered ideal candidates for drug delivery applications due to their easy synthesis, excellent mechanical properties, and biodegradability. Unfortunately, methods for preparing well-defined PU nanoparticles required miniemulsion polymerization techniques with a nontrivial control of the polymerization conditions due to the inherent incompatibility of isocyanate-containing monomers and water. In this work, we report the preparation of soft PU nanoparticles in a one-pot process using interfacial polymerization that employs a non-isocyanate polymerization route that minimizes side reactions with water. Activated pentafluorophenyl dicarbonates were polymerized with diamines and/or triamines by interfacial polymerization in the presence of an anionic emulsifier, which afforded non-isocyanate polyurethane (NIPU) nanoparticles with sizes in the range of 200-300 nm. Notably, 5 wt % of emulsifier was required in combination with a trifunctional amine to achieve stable PU dispersions and avoid particle aggregation. The versatility of this polymerization process allows for incorporation of functional groups into the PU nanoparticles, such as carboxylic acids, which can encapsulate the chemotherapeutic doxorubicin through ionic interactions. Altogether, this waterborne synthetic method for functionalized NIPU soft nanoparticles holds great promise for the preparation of drug delivery nanocarriers.

Synergistic chemotherapeutic effect of sorafenib-loaded pullulan-Dox conjugate nanoparticles against murine breast carcinoma

pH-Sensitive pullulan-doxorubicin conjugates encapsulating sorafenib (P-Dox/S) nanoparticles were developed as a synergistic combinatorial delivery system against murine breast carcinoma. The nanoparticles can encapsulate Dox and sorafenib with ultra-high loading capacity (65.34 wt%) through chemical conjugation and physical loading, whereas can remain stable under physiological conditions and gradually release Dox and sorafenib with the decreasing pH. These conjugates can be effectively internalized and clearly suppress 4T1 cell growth in vitro. Furthermore, research data of in vivo animal models revealed that the synergistic combinatorial P-Dox/S nanoparticles heavily accumulated in solid tumor tissue sites to maximize therapeutic efficacy; they also significantly inhibited solid tumor growth, even remarkably reduced solid tumor volume in comparison to the initial volume, and obviously diminished adverse effects. The anti-tumor therapeutic effect obviously outperformed the delivery of combinational chemotherapy of free drugs or single drug-loaded P-Dox nanoparticles at the same concentration. These promising results indicate the high-efficiency synergistic chemotherapeutic effects of these nanoparticles. Combinational chemotherapy using P-Dox/S nanoparticles has important potential in the clinical treatment of malignancy for overcoming drug resistance and heterogeneity.

Dual-pH-sensitivity and tumour targeting core–shell particles for intracellular drug delivery

The principal problem in the area of drug delivery is achieving better selectivity and controllability.

Doxorubicin Delivery Using pH and Redox Dual-Responsive Hollow Nanocapsules with a Cationic Electrostatic Barrier

For the delivery of doxorubicin (DOX), pH and redox dual responsive hollow nanocapsules were prepared through the stabilization of polymer vesicles, which spontaneously formed from polyamidoamine dendron-poly(l-lysine) (PAMAM dendron-PLL), by the introduction of disulfide (SS) bonds between PLLs. The SS-bonded nanocapsules exhibited a very slow release of DOX under an extracellular environment because the cationic PLL membrane acted as an electrostatic barrier against the protonated DOX molecules. However, increasing the glutathione concentration to the intracellular level facilitated the immediate release of DOX through the collapse of nanocapsules by the spontaneous cleavage of SS bonds. SS-bonded nanocapsules also escaped from the endosome by the buffering effect of PAMAM dendrons, and DOX delivery into the cytoplasm was achieved. Furthermore, DOX molecules delivered by SS-bonded nanocapsules exhibited an effective in vitro anticancer effect to HeLa cells.

Carbohydrate-based amphiphilic nano delivery systems for cancer therapy

Nanoparticles (NPs) are novel drug delivery systems that have been attracting more and more attention in recent years, and have been used for the treatment of cancer, infection, inflammation and other diseases. Among the numerous classes of materials employed for constructing NPs, organic polymers are outstanding due to the flexibility of design and synthesis and the ease of modification and functionalization. In particular, NP based amphiphilic polymers make a great contribution to the delivery of poorly-water soluble drugs. For example, natural, biocompatible and biodegradable products like polysaccharides are widely used as building blocks for the preparation of such drug delivery vehicles. This review will detail carbohydrate based amphiphilic polymeric systems for cancer therapy. Specifically, it focuses on the nature of the polymer employed for the preparation of targeted nanocarriers, the synthetic methods, as well as strategies for the application and evaluation of biological activity. Applications of the amphiphilic polymer systems include drug delivery, gene delivery, photosensitizer delivery, diagnostic imaging and specific ligand-assisted cellular uptake. As a result, a thorough understanding of the relationship between chemical structure and biological properties facilitate the optimal design and rational clinical application of the resulting carbohydrate based nano delivery systems for cancer therapy.

Dual Stimuli-Responsive Hybrid Polymeric Nanoparticles Self-Assembled from POSS-Based Starlike Copolymer-Drug Conjugates for Efficient Intracellular Delivery of Hydrophobic Drugs

To further fine tune drug release and enhance therapeutic effects of polyhedral oligomericsilsesquioxane (POSS)-based nanomedicine, a starlike organic-inorganic conjugate was synthesized by grafting semitelechelic N-(2-hydroxypropyl) methacrylamide (HPMA) copolymers to a POSS rigid core through reductively degradable disulfide bonds. The hydrophobic docetaxel (DTX) was attached to the grafts by pH-sensitive hydrazone bonds and also encapsulated into the POSS core (SP-DTX). Thus, the final amphiphilic star-shaped conjugates could self-assemble into nanoparticles and exhibited conspicuous drug-loading capacity (20.1 wt %) based on the covalently conjugated accompanied by physically encapsulated DTX. The stimuli-responsive DTX release under acidic lysosomal and reducing cytoplasmic environments was verified, leading to enhanced cytotoxicity against PC-3 human prostate carcinoma cells. To evaluate the in vivo therapeutic effects of the DTX-loaded nanovehicles objectively, a stroma-rich, prostate xenograft tumor model was generated. SP-DTX displayed uniform tumor distribution and suppressed tumor growth to a more pronounced level (tumor inhibition of 78.9%) than nonredox-sensitive SP-DTX-A (67.4%), SP-DTX-C contained DTX only in the core (65.5%) or linear P-DTX (60.7%) through enhanced depletion of cancer-associated fibroblasts and induction of apoptosis. The hybrid POSS-based polymeric nanoparticles offer an efficient approach to transport hydrophobic drugs for cancer therapy.

The Promising Nanocarrier for Doxorubicin and siRNA Co-delivery by PDMAEMA-based Amphiphilic Nanomicelles

Synergistic effects of anticancer drug and siRNA have displayed superior advantages for cancer therapy. Herein, we deeply analyzed the feasibility that whether doxorubicin (DOX) and siRNA could be co-delivered by mPEG-PCL-graft-PDMAEMA (PECD) micelles, which mediated excellent DNA/siRNA delivery in vitro and in vivo reported in our previous work. DOX-loaded NPs (PECD-D) were developed by nanoprecipitation technology and exhibited high drug loading content (DLC, 9.5%). In vitro cytotoxicity study in MDA-MB-231 cells, PECD-D treated groups had lower IC50 compared to free DOX groups (F-DOX) at different transfection time (24, 48, and 72h), which maybe attribute to its high cellular uptake and endosomal escape properties. The speculation was confirmed with the results of drug release profile in acidic media, flow cytometry analysis and confocal images. Futhermore, Cy5 labeled siRNA was introduced in PECD-D micelles (PECD-D/siRNA) to track the behavior of dual-loaded nanodrug in vitro and in vivo. Flow cytometry analysis presented that DOX and siRNA were successfully co-delivered into cells, the positive cells ratio were 94.6 and 99.5%, respectively. Confocal images showed that not only DOX and siRNA existed in cytoplasm, but DOX traversed endosome/lysosome and entered into cell nucleus. For in vivo tumor-targeting evaluation in BALB/c nude mice, both DOX and Cy5-siRNA could be detected in tumor sites after intravenous injection with PECD-D/siRNA formulation. Therefore, we believed that PECD micelles have a potential ability as DOX and siRNA co-delivery carrier for cancer therapy.

Reduction-Degradable Polymeric Micelles Decorated with PArg for Improving Anticancer Drug Delivery Efficacy

In this study, five kinds of reduction-degradable polyamide amine-g-polyethylene glycol/polyarginine (PAA-g-PEG/PArg) micelles with different proportions of hydrophilic and hydrophobic segments were synthesized as novel drug delivery vehicles. Polyarginine not only acted as a hydrophilic segment but also possessed a cell-penetrating function to carry out a rapid transduction into target cells. Polyamide amine-g-polyethylene glycol (PAA-g-PEG) was prepared for comparison. The characterization and antitumor effect of the DOX-incorporated PAA-g-PEG/PArg cationic polymeric micelles were investigated in vitro and in vivo. The cytotoxicity experiments demonstrated that the PAA-g-PEG/PArg micelles have good biocompatibility. Compared with DOX-incorporated PAA-g-PEG micelles, the DOX-incorporated PAA-g-PEG/PArg micelles were more efficiently internalized into human hepatocellular carcinoma (HepG2) cells and more rapidly released DOX into the cytoplasm to inhibit cell proliferation. In the 4T1-bearing nude mouse tumor models, the DOX-incorporated PAA-g-PEG/PArg micelles could efficiently accumulate in the tumor site and had a longer accumulation time and more significant aggregation concentration than those of PAA-g-PEG micelles. Meanwhile, it excellently inhibited the solid tumor growth and extended the survival period of the tumor-bearing Balb/c mice. These results could be attributed to their appropriate nanosize and the cell-penetrating peculiarity of polyarginine as a surface layer. The PAA-g-PEG/PArg polymeric micelles as a safe and high efficiency drug delivery system were expected to be a promising delivery carrier that targeted hydrophobic chemotherapy drugs to tumors and significantly enhanced antitumor effects.

pH-Triggered copolymer micelles as drug nanocarriers for intracellular delivery

We prepared pH-sensitive polymeric micelles which were used as nano-carriers and exhibited a high loading capacity and pH-triggered release of DOX.