Combination of polythyleneimine regulating autophagy prodrug and Mdr1 siRNA for tumor multidrug resistance.

Multidrug resistance (MDR) has been restricting the efficacy of chemotherapy, which mainly include pump resistance and non-pump resistance. In order to fight overall MDR, a novel targeted gene/drug co-deliver nano system is developed, which can suppress the drug efflux pumps and modulate autophagy to overcoming both pump and non-pump resistance. Here, small interfere RNA (siRNA) is incorporated into polymer-drug conjugates (PEI-PTX, PP) which are composed of polyethyleneimine (PEI) and paclitaxel (PTX) via covalent bonds, and hyaluronic acid (HA) is coated on the surface of PP/siRNA to achieve long blood cycle and CD44-targeted delivery. The RNA interference to mdr1 gene is combined with autophagy inhibition by PP, which efficiently facilitate apoptosis of Taxol-resistant lung cancer cells (A549/T). Further study indicates that PEI in PP may play a significant role to block the autophagosome-lysosome fusion process by means of alkalizing lysosomes. Both in vitro and in vivo studies confirm that the nanoassemblies can successfully deliver PTX and siRNA into tumor cells and significantly inhibited A549/T tumor growth. In summary, the polymeric nanoassemblies provide a potential strategy for combating both pump and non-pump resistance via the synergism of RNAi and autophagy modulation.

Intracellular tracking of drug release from pH-sensitive polymeric nanoparticles via FRET for synergistic chemo-photodynamic therapy.

BACKGROUND: Synergistic therapy of tumor is a promising way in curing cancer and in order to achieve effective tumor therapy with real-time drug release monitoring, dynamic cellular imaging and antitumor activity. RESULTS: In this work, a polymeric nanoparticle with Forster resonance energy transfer (FRET) effect and chemo-photodynamic properties was fabricated as the drug vehicle. An amphiphilic polymer of cyclo(RGDfCSH) (cRGD)-poly(ethylene glycol) (PEG)-Poly(L-histidine) (PH)-poly(ε-caprolactone) (PCL)-Protoporphyrin (Por)-acting as both a photosensitizer for photodynamic therapy (PDT) and absorption of acceptor in FRET was synthesized and self-assembled into polymeric nanoparticles with epirubicin (EPI)-acting as an antitumor drug for chemotherapy and fluorescence of donor in FRET. Spherical EPI-loaded nanoparticles with the average size of 150 ± 2.4 nm was procured with negatively charged surface, pH sensitivity and high drug loading content (14.9 ± 1.5%). The cellular uptake of EPI-loaded cRGD-PEG-PH-PCL-Por was monitored in real time by the FRET effect between EPI and cRGD-PEG-PH-PCL-Por. The polymeric nanoparticles combined PDT and chemotherapy showed significant anticancer activity both in vitro (IC50 = 0.47 µg/mL) and better therapeutic efficacy than that of free EPI in vivo. CONCLUSIONS: This work provided a versatile strategy to fabricate nanoassemblies for intracellular tracking of drug release and synergistic chemo-photodynamic therapy.

Combined Ibuprofen-Nanoconjugate Micelles with E-Selectin for Effective Sunitinib Anticancer Therapy.

Introduction: Sunitinib, a first-line therapy with a certain effect, was utilized in the early stages of renal cell carcinoma treatment. However, its clinical toxicity, side effects, and its limited bioavailability, resulted in inadequate clinical therapeutic efficacy. Building neoteric, simple, and safe drug delivery systems with existing drugs offers new options. Therefore, we aimed to construct a micelle to improve the clinical efficacy of sunitinib by reusing ibuprofen. Methods: We synthesized the sialic acid-poly (ethylene glycol)-ibuprofen (SA-PEG-IBU) amphipathic conjugate in two-step reaction. The SA-PEG-IBU amphiphilic conjugates can form into stable SPI nanomicelles in aqueous solution, which can be further loaded sunitinib (SU) to obtain the SPI/SU system. Following nanomicelle creation, sialic acid exposed to the nanomicelle surface can recognize the overexpressed E-selectin receptor on the membrane of cancer cells to enhance cellular uptake. The properties of morphology, stability, and drug release about the SPI/SU nanomicelles were investigated. Confocal microscopy and flow cytometry were used to assess the cellular uptake efficiency of nanomicelles in vitro. Finally, a xenograft tumor model in nude mice was constructed to investigate the body distribution and tumor suppression of SPI/SU in vivo. Results: The result showed that SPI nanomicelles exhibited excellent tumor targeting performance and inhibited the migration and invasion of tumor cell in vitro. The SPI nanomicelles can improve the accumulation of drugs in the tumor site that showed effective tumor inhibition in vivo. In addition, H&E staining and immunohistochemical analysis demonstrated that the SPI/SU nanomicelles had a superior therapeutic effect and lower biotoxicity. Conclusion: The SPI/SU nanomicelles displayed excellent anti-tumor ability, and can suppress the metastasis of tumor cell by decreasing the expression of Cyclooxygenase-2 due to the ibuprofen, providing an optimistic clinical application potential by developing a simple but safe drug delivery system.

Healing Effects of Curcumin Nanoparticles in Deep Tissue Injury Mouse Model.

BACKGROUND: Chronic inflammation and lack of angiogenesis are the important pathological mechanisms in Deep Tissue Injury (DTI). Curcumin is a well-known anti-inflammatory and antioxidant agent. However, curcumin is unstable under acidic and alkaline conditions and can be rapidly metabolized and excreted in the bile, which shortens its bioactivity and efficacy. OBJECTIVE: This study aimed to prepare curcumin-loaded poly (lactic-co-glycolic acid) nanoparticles (CPNPs) and to elucidate the protective effects and underlying mechanisms of wound healing in DTI models. METHODS: CPNPs were evaluated for particle size, biocompatibility, in vitro drug release and their effect on in vivo wound healing. RESULTS: The results of in vivo wound closure analysis revealed that CPNP treatments significantly improved wound contraction rates (p<0.01) at a faster rate than the other three treatment groups. H&E staining revealed that CPNP treatments resulted in complete epithelialization and thick granulation tissue formation. In contrast, control groups resulted in a lack of compact epithelialization and persistence of inflammatory cells within the wound sites. Quantitative real-time PCR analysis showed that treatment with CPNPs suppressed IL-6 and TNF-α mRNA expression, and up-regulated TGF-ß, VEGF-A and IL-10 mRNA expression. Western blot analysis showed up-regulated protein expression of TGF-ß, VEGF-A and phosphorylated-STAT3. CONCLUSION: Our results showed that CPNPs enhanced wound healing in DTI models through modulation of the JAK2/STAT3 signalling pathway and subsequent upregulation of pro-healing factors.

Reduction-sensitive polymeric micelles as amplifying oxidative stress vehicles for enhanced antitumor therapy.

Chemotherapy-photodynamic therapy (PDT)-based combination therapy is a currently frequently used means in cancer treatment that photosensitizer was able to generate reactive oxygen species (ROS) for improving chemotherapy, owing to the high oxidative stress of the tumor microenvironment (TME). Whereas, cancer cells were accustomed to oxidative stress by overexpression of antioxidant such as glutathione (GSH), which would consume the damage of ROS, as well as it could result in ineffective treatment. Herein, amplification of oxidative stress preferentially in tumor cells by consuming GSH or generating ROS is a reasonable treatment strategy to develop anticancer drugs. To achieve excellent therapeutic effects, we designed a GSH-scavenging and ROS-generating polymeric micelle mPEG-S-S-PCL-Por (MSLP) for amplifying oxidative stress and enhanced anticancer therapy. The amphiphilic polymer of methoxy poly(ethylene glycol) (mPEG)-S-S-poly(ε-caprolactone) (PCL)-Protoporphyrin (Por) was self-assembled into polymeric micelles with the anticancer drug doxorubicin (DOX) for treatment and tracking via FRET. Spherical DOX/MSLP micelles with the average size of 88.76 ±â€¯3.52 nm was procured with negatively charged surface, reduction sensitivity and high drug loading content (17.47 ±â€¯1.53 %). The intracellular ROS detection showed that the MSLP could deplete glutathione and regenerate additional ROS. The cellular uptake of DOX/MSLP micelles was grabbed real-time monitoring by the Fluorescence resonance energy transfer (FRET) effect between DOX and MSLP. The reduction-sensitive polymeric micelles MSLP as amplifying oxidative stress vehicles combined chemotherapy and PDT exhibited significant antitumor activity both in vitro (IC50 = 0.041 µg/mL) and much better antitumor efficacy than that of mPEG-PCL-Por (MLP) micelles in vivo.

Mechanism Investigation of Hyaluronidase-Combined Multistage Nanoparticles for Solid Tumor Penetration and Antitumor Effect.

BACKGROUND: Hyaluronic acid (HA) is a major component of extracellular matrix (ECM) and its over expression in tumor tissues contributes to the increase of interstitial fluid pressure (IFP) and hinders the penetration of nanoparticles into solid tumors. MATERIALS AND METHODS: We here reported a tumoral microenvironment responsive multistage drug delivery system (NPs-EPI/HAase) which was formed layer by layer via electrostatic interaction with epirubicin (EPI)-loaded PEG-b-poly(2-(diisopropylamino)ethyl methacrylate)-b-poly(2-guanidinoethylmethacrylate) (mPEG-PDPA-PG, PEDG) micelles (NPs-EPI) and hyaluronidase (HAase). In this paper, we focused on the hyaluronidase-combined nanoparticles (NPs-EPI/HAase) for tumor penetration in tumor spheroid and solid tumor models in vitro and in vivo. RESULTS: Our results showed that NPs-EPI/HAase effectively degrade the HA in ECM and facilitate deep penetration of NPs-EPI into solid tumor. Moreover, NPs-EPI mainly employed clathrin-mediated and macropinocytosis-mediated endocytic pathways for cellular uptake and were subsequently directed to the lysosomes for further drug release triggered by proton sponge effect. Compared with NPs-EPI, the HAase coating group showed an enhanced tumoral drug delivery efficacy and inhibition of tumor growth. CONCLUSION: Overall, our studies demonstrated that coating nanoparticles with HAase can provide a simple but efficient strategy for nano-drug carriers to enhance solid tumor penetration and chemotherapeutic efficacy.

Novel polymeric micelles as enzyme-sensitive nuclear-targeted dual-functional drug delivery vehicles for enhanced 9-nitro-20(S)-camptothecin delivery and antitumor efficacy.

9-Nitro-20(S)-camptothecin (9-NC) is a broad-spectrum antitumor drug used in tumor treatments, but its clinical applications and antitumor efficacy are limited by its structural instability, poor solubility, and extremely low drug utilization in tumor tissues. In this study, enzyme-sensitive nuclear-targeted dual-functional polymeric micelles were developed for 9-NC delivery with a high drug loading content (12.93 ± 0.88%), steady-state circulation, and a rapid attack at the "heart" of tumor cells. Briefly, chrysin (CHR) as a π-conjugated moiety was immobilized on the PCL terminal in the TAT-PCL amphiphiles and combined with the ALAL peptide as a linker on HA chains to yield the ultimate CHR-PCL-TAT-ALAL-HA (HATPC) amphiphiles. Spherical 9-NC-loaded micelles were obtained from the self-assembly of the dual-functional amphiphiles comprising HATPC and 9-NC with uniform nanosize (121.6 ± 5.79 nm), well-distributed morphology (PDI: 0.256), and negative surface charge (-23.2 ± 0.5 mV), yielding high stability during blood circulation. In this drug delivery system, HA acts as an active tumor-targeting instrument via CD44-receptor-mediated endocytosis; further, the ALAL peptide could be cutoff in the lysosomes of the tumor cells due to the high expression of cathepsin B, leading to lysosomal escape, while the secondary polymeric micelles targeted the tumor cell nucleus via the exposed TAT peptide. The enzyme sensitivity and nuclei targetability of the 9-NC/HATPC micelles were confirmed by dynamic light scattering and confocal laser scanning microscopy analyses. As compared to free 9-NC and traditional mPEG2k-PCL2k polymeric micelles, 9-NC/HATPC micelles were the most concentrated in the tumor cell nucleus; therefore, they exhibited the highest cytotoxicity against SKOV3 tumor cells both in vitro (IC50 = 0.03 µg mL-1) and in vivo. This enzyme-sensitive nuclear-targeted dual-functional drug delivery system involving HATPC provided a new and promising strategy for enhanced 9-NC delivery and antitumor efficacy.

Preparation of Icaritin-Loaded mPEG-PLA Micelles and Evaluation on Ischemic Brain Injury.

Icaritin is an active ingredient derived from the plant Herba Epimedium, which exhibits various pharmacological and biological activities. However, icaritin has solubility in water of less than 1.0 µg/ml and the low aqueous solubility hampered its use as a therapeutic agent. In this work, as shown in Scheme 1, we synthesized a series of mPEG-PLA (Methyl poly (ethylene glycol)-Polylactic acid) with different hydrophilic and hydrophobic segment ratios via ring-opening polymerization and prepared mPEG-PLA/icaritin micelles by solid dispersion method to improve the solubility of icaritin. After studying the particle size, zeta potential, encapsulation efficiency and drug loading efficiency, mPEG2000-PLA50(hydrophilic/hydrophobic segment ratio = 5:6) was selected for subsequent experiment, including single factor experiments and orthogonal experiments for optimizing mPEG-PLA (5:6)/icaritin micelles preparation. The particle size and zeta potential of the mPEG-PLA (5:6)/icaritin micelles were about (64.25 ± 0.21) nm and (-1.37 ± 0.31) mV, the encapsulation efficiency (EE) and drug loading efficiency (DL) were 83.96% and 9.33%, the critical micelle concentration was about 2.24 µg/ml and the solubility about 2.0 mg/ml in water. In vivo studies have shown that mPEG-PLA (5:6)/icaritin micelles have a longer circulation time in plasma and have a distribution in the brain of mice. The pharmacodynamic results indicated that pretreatment with mPEG-PLA (5:6)/icaritin micelles can decrease neurological deficit score, diminish the infarct volume and brain edema. These results suggested that mPEG-PLA (5:6)/icaritin micelles have a good advantage to improve the bioavailability of icaritin, potentially to be a neuroprotectant for ischemic brain injury.

LDH hybrid thermosensitive hydrogel for intravaginal delivery of anti-HIV drugs.

Microbicides based on hydrogel have become an effective way to prevent the HIV replication and transmission because of their convenience and prolonging drug release. In this study, a hybrid thermo-sensitive hydrogel constituted by nanosized layered double hydroxides and poloxamer 407 (P407) was constructed and co-loaded with both hydrophobic and hydrophilic drug. The LDH-P407 hydrogel could achieve sol-gel transition at body temperature. The in vivo experiment showed that LDH-P407 hydrogel can achieve controlled release of theaflavin and Nile red (hydrophobic drug model) into blood by vaginal drug delivery, meanwhile the hydrogel showed barely mucosal irritation. In addition, ex vivo experiment showed that the nifeviroc-loaded LDH-P407 hydrogel was able to specifically bind co-receptor CCR5 of DCs cells. Therefore, the LDH-P407 hydrogel would be a promising carrier for intravaginal delivery of anti-HIV drugs.

ECM based injectable thermo-sensitive hydrogel on the recovery of injured cartilage induced by osteoarthritis.

Intra-articular injection of anti-inflammatory drugs can be a promising strategy for recovery of injured articular cartilage. We prepared a series of injectable thermo-sensitive composite hydrogels, composed of Pluronic F127, glycosaminoglycan (GAG) and bone morphogenetic protein (BMP-2), which was designed to mimic extracellular matrix (ECM). The rheological properties and dissolution rate of composite hydrogels containing chondroitin sulfate or with different hyaluronic acid molecular mass (10k, 90k, 800k) were investigated. Meanwhile, bovine serum albumin (BSA) or FITC-BSA was chosen as model drug loaded into PF/GAG hydrogels to study their sustained release behavior in vitro. The results showed that hydrogels could maintain shapes for more than 16 days and the release rate of BSA in PF/GAG composite gels was much slower than in PF127 gels, due to the affinity between BSA and GAG. Furthermore, increasing the molecular weight of hyaluronic acid correspondingly increased hydrogel dissolution rate and BSA release in the hydrogels. Subsequently, MTT experiments were performed to investigate the toxicity of the hydrogels on mouse pre-osteoblast cell MC3T3-E1. In vivo anti-inflammation results showed that PF/GAG@BMP-2 composite hydrogels had the most efficient efficacy on recovery of injured cartilage, which is induced by osteoarthritis, compared to the control groups (PF127@BMP-2 or BMP-2 saline solution).

Mechanistic insight into the interaction of gastrointestinal mucus with oral diblock copolymers synthesized via ATRP method.

INTRODUCTION: Nanoparticles are increasingly used as drug carriers for oral administration. The delivery of drug molecules is largely dependent on the interaction of nanocarriers and gastrointestinal (GI) mucus, a critical barrier that regulates drug absorption. It is therefore important to understand the effects of physical and chemical properties of nanocarriers on the interaction with GI mucus. Unfortunately, most of the nanoparticles are unable to be prepared with satisfactory structural monodispersity to comprehensively investigate the interaction. With controlled size, shape, and surface chemistry, copolymers are ideal candidates for such purpose. MATERIALS AND METHODS: We synthesized a series of diblock copolymers via the atom transfer radical polymerization method and investigated the GI mucus permeability in vitro and in vivo. RESULTS: Our results indicated that uncharged and hydrophobic copolymers exhibited enhanced GI absorption. CONCLUSION: These results provide insights into developing optimal nanocarriers for oral administration.

Viral Capsids Mimicking Based on pH-Sensitive Biodegradable Polymeric Micelles for Efficient Anticancer Drug Delivery.

Bio-inspired supramolecular self-assembly have been widely explored in biomedical engineering, especially in the field of drug delivery. Here, viral capsid analogue pH-Sensitive polymeric micelles HA-Hyd-DOX were reported, where natural polysacarrides hyaluronic acid (HA) and anticancer drug doxorubicin (DOX), were linked through a hydrazone bond with a high drug loading content of 33.09 wt%. The polymeric micelles look like artificial virus capsids from "core-shell" structures. In addition, the polymeric backbone HA and hydrazone bonds were destroyed in the presence of hyaluronidase in cancer cells and under the acidic conditions of pH = 5 respectively, thereby prodrug-based polymeric micelles could penetrate into the tumor and DOX could be released in lysosomes to enhance anticancer efficacy. With the comparison of typical prodrug-based polymeric micelles mPEG-Hyd-DOX system where DOX was linked to methoxy poly(ethylene glycol) with a hydrazone bond linkage, HA-Hyd-DOX showed greater inhibition to cancer cells due to the better penetration. Such viral capsids mimicking polymeric micelles provided some remarkable benefits for drug delivery, including, high drug loading efficiency, controlled drug release and excellent biodegradable.

Preparation and evaluation of tumour microenvironment response multistage nanoparticles for epirubicin delivery and deep tumour penetration.

Poor tumour penetration became a major challenge for the use of nanoparticles in anticancer therapy. To further enhance the tumour penetration efficiency, we developed a tumour-microenvironment-responsive multistage drug delivery system which was formed layer by layer via electrostatic interaction with cationic drug-loaded nanoparticles, hyaluronidase (HAase) and iRGD-modified gelatin (G-iRGD). The drug-loaded nanoparticles were formed by self-assembling mPEG-PDPA-PG and encapsulation with epirubicin (EPI). Due to the protonation of tertiary amine groups of PDPA segment in acid environment, mPEG-PDPA-PG could enhance the lysosomal escape and the intracellular release of EPI. This NPs/HAase/G-iRGD delivery system showed great biocompatibility in vitro, confirmed by MTT method. In vitro spherical tumour model penetration and in vivo tumour permeability investigation showed HAase coated NPs-EPI (NPs-EPI/HAase) could significantly enhance its penetrating efficiency. The NPs-EPI/HAase could assist in breaking down the hyaluronic acid (HA), which was a key component of extracellular matrix and thereby improving mass transport within the solid tumours. The flow cytometry studies showed that G-iRGD coated NPs-EPI (NPs-EPI/G-iRGD) was more easily taken up by HepG2 cells than gelatin coated NPs-EPI (NPs-EPI/G), which revealed the active targeting ability of iRGD. The results proved that this NPs/HAase/G-iRGD delivery system showed promising potential in enhancing tumour penetration efficiency.

Fluorescence Resonance Energy Transfer Visualization of Molecular Delivery from Polymeric Micelles.

Polymeric micelles are important carriers for anticancer drug delivery. However, rare papers focused on the dynamic of drug in the core of micelles. In this paper, we used fluorescence resonance energy transfer (FRET) technique to investigate the dynamic diffusion of drug from polymeric micelles. mPEG-PCL diblock copolymers were used as carriers. A pair of fluorescence molecules Cy3 and Cy5 was selected to evoke the FRET phenomenon. Cy5 was immobilized on the terminal group of PCL segments, Cy3 was encapsulated in the Cy5 modified polymeric micelles as the model drug. The drug loaded polymeric micelles were incubated with 4T1 breast cancer cells. The FRET was observed to explore the dynamic of Cy3 in the micelles. The results showed that the Cy3 loaded micelles were stable in aqueous solution as the energy-transfer efficiency (ETE, I660/I565) rarely decreased even when the time was as long as 120 h. The ETE increased with the content of encapsulated Cy3. The FRET spectra showed that the ETE of the Cy3 loaded polymeric micelles lowered with the release of Cy3 in PBS. The intracellular tracking of the Cy3 loaded micelles found more than 60% loaded drug was release within 12 h with the calculation of ETE in FRET spectra and it was same to confocal laser scanning and flow cytometry results.

Structural mediation on polycation nanoparticles by sulfadiazine to enhance DNA transfection efficiency and reduce toxicity.

Reducing the toxicity while maintaining high transfection efficiency is an important issue for cationic polymers as gene carriers in clinical application. In this paper, a new zwitterionic copolymer, polycaprolactone-g-poly(dimethylaminoethyl methyacrylate-co-sulfadiazine methacrylate) (PC-SDZ) with unique pH-sensitivity, was designed and prepared. The incorporation of sulfadiazine into poly(dimethylaminoethyl methacrylate) (PDMAEMA) chains successfully mediates the surface properties including compacter shell structure, lower density of positive charges, stronger proton buffer capability, and enhanced hydrophobicity, which lead to reduction in toxicity and enhancements in stability, cellular uptake, endosome escape, and transfection efficiency for the PC-SDZ2 nanoparticles (NPs)/DNA complexes. Excellent transfection efficiency at the optimal N/P ratio of 10 was observed for PC-SDZ2 NPs/DNA complexes, which was higher than that of the commercial reagent-branched polyethylenimine (PEI). The cytotoxicity was evaluated by CCK8 measurement, and the results showed significant reduction in cytotoxicity even at high concentration of complexes after sulfadiazine modification. Therefore, this work may demonstrate a new way of structural mediation of cationic polymer carriers for gene delivery with high efficiency and low toxicity.

Effects of hydrophobic core components in amphiphilic PDMAEMA nanoparticles on siRNA delivery.

Due to their biodegradable character, polyesters such as polycaprolactone (PCL), poly(D,L-lactide) (PDLLA), and polylactic-co-glycolic acid (PLGA) were widely used as the hydrophobic cores of amphiphilic cationic nanoparticles (NPs) for siRNA delivery. However, fewer researches focused on facilitating siRNA delivery by adjusting the polyester composition of these nanoparticles. Herein, we investigated the contribution of polyester segments in siRNA delivery in vitro by introducing different ratio of DLLA moieties in PCL segments of mPEG-block-PCL-graft-poly(dimethylamino ethyl methacrylate)(PEG-b-PCL-g-PDMAEMA). It was noticed that compared with the other ratios of DLLA moieties, a certain molar ratio (about 70%) of the NPs, named mPEG45-P(CL21-co-DLLA48)-g-(PDMAEMA29)2 (PECLD-70), showed the highest gene knockdown efficiency but poorest cellular uptake ability in vitro. Further research revealed that NPs with various compositions of the polyester cores showed different physicochemical properties including particle size, zeta potential and stiffness, leading to different endocytosis mechanisms thus influencing the cellular uptake efficiency. Subsequently, we observed that the cells treated by PECLD-70 NPs/Cy5 siRNA complexes exhibited more diffuse Cy5 signal distribution than other NPs by confocal laser scanning microscope, which suggested that siRNA delivered by PECLD-70 NPs/Cy5 siRNA complexes possessed of stronger capabilities in escaping from endosome/lysosome, entering the RNA-induced silencing complex (RISC) and cutting the target mRNA efficiently. The different siRNA release profile was dominated by the degradation rate of polyester segments. Therefore, it could be concluded that the adjustment of hydrophobic core of cationic nanoparticles could significantly affect their transfection behavior and appropriate polyester composition should be concerned in designing of analogous siRNA vectors.

Facile access to cytocompatible multicompartment micelles with adjustable Janus-cores from A-block-B-graft-C terpolymers prepared by combination of ROP and ATRP.

The architecture of hydrophobic segments can determine the specific morphology of multicompartment micelles (MCMs) that are generated from aqueous assembly of amphiphilic terpolymers. In this study, we aimed to design and generate poly(ɛ-caprolactone)-based multicompartment micelles with adjustable Janus-cores. Well-defined terpolymers with a novel A-block-B-graft-C architecture composed of biologically compatible polymers, methoxy poly(ethylene glycol) (PEG), poly(ɛ-caprolactone) (PCL) and poly(2-(perfluorobutyl)ethyl methacrylate) (PPFEMA), were prepared by the stepwise use of ring-opening polymerization and atom transfer radical polymerization. Characterization of the obtained terpolymers was carried out by (1)H NMR and gel permeation chromatography. Results from differential scanning calorimetry and X-ray diffraction studies indicated that within the terpolymer structure, the PCL segments are in the crystalline state, while fluorocarbon segments belong to the amorphous domains. Due to the thermodynamic incompatibility of PCL and PPFEMA, MCMs could be obtained upon aqueous self-assembly of the terpolymer. The well-segregated Janus-cores with adjustable compartment balance were revealed by transmission electron microscopy. In vitro cell viability assays further demonstrated an excellent cytocompatibility of the MCMs both in mouse embryonic fibroblasts (3T3) and human acute monocytic leukemia (THP-1) cells.

Contribution of hydrophobic/hydrophilic modification on cationic chains of poly(ε-caprolactone)-graft-poly(dimethylamino ethylmethacrylate) amphiphilic co-polymer in gene delivery.

Nanoparticles (NPs) assembled from amphiphilic polycations have been certified as potential carriers for gene delivery. Structural modification of polycation moieties may be an efficient route to further enhance gene delivery efficiency. In this study two electroneutral monomers with different hydrophobicities, 2-hydroxyethyl methacrylate (HEMA) and 2-hydroxyethyl acrylate (HEA), were incorporated into the cationic poly(dimethylamino ethyl methacrylate) (PDMAEMA) side-chains of amphiphilic poly(ε-caprolactone)-graft-poly(dimethylamino ethylmethacrylate) (PCD) by random co-polymerization, to obtain poly(ε-caprolactone)-graft-poly(dimethylamino ethyl methacrylate-co-2-hydroxyethyl methacrylate) (PCD-HEMA) and poly(ε-caprolactone)-graft-poly(dimethylamino ethyl methacrylate-co-2-hydroxyethyl acrylate) (PCD-HEA). Minimal HEA or HEMA moieties in PDMAEMA do not lead to statistically significant changes in particle size, zeta potential, DNA condensation properties and buffering capacity of the naked NPs. However, the incorporation of HEMA and HEA lead to reductions and increases, respectively, in the surface hydrophilicity of the naked NPs and NPs/DNA complexes, which was confirmed by water contact angle assay. These simple modifications of PDMAEMA with HEA and HEMA moieties significantly affect the gene transfection efficiency on HeLa cells in vitro: PCD-HEMA NP/DNA complexes show a much higher transfection efficiency than PCD NPs/DNA complexes, while PCD-HEA NPs/DNA complexes show a lower transfection efficiency than PCD NP/DNA complexes. Fluorescence activated cell sorter and confocal laser scanning microscope results indicate that the incorporation of hydrophobic HEMA moieties facilitates an enhancement in both cellular uptake and endosomal/lysosomal escape, leading to a higher transfection efficiency. Moreover, the process of endosomal/lysosomal escape confirmed in our research that PCD and its derivatives do not just rely on the proton sponge mechanism, but also on membrane damage due to the polycation chains, especially hydrophobic modified ones. Hence, it is proved that hydrophobic modification of cationic side-chains is a crucial route to improve gene transfection mediated by polycation NPs.

Preparation and investigation of high solid content PTX-loaded nanoparticles dispersion via nanoprecipitation method.

The improvement of the solid content of the hydrophobic drugs (such as paclitaxel (PTX), etc.) loaded nanoparticles (NPs) dispersion is important for enhancing drug-loaded efficiency and reducing the cost in production and application. A diblock copolymer methoxy poly(ethylene glycol)-b-poly(ε-caprolactone-co-1,4,8-trioxa[4.6]spiro-9-undecanone) (mPECT) is synthesized via the ring-opening polymerization of ε-caprolactone and 1,4,8-trioxa[4.6]spiro-9-undecanone (TOSUO) with methoxy poly(ethyleneglycol) (mPEG） as the initiator. The chemical structures and thermal properties of mPECT are characterized by (1)HNMR, Fourier transform infrared (FT-IR), gel permeation chromatography, differential scanning calorimetry, etc. PEG45.45-b-P(C28.33-co-T5.38) (mPECT-2) is able to self-assemble into stable NPs in water via nanoprecipitation method at a high solid content (≤25 wt%) and their freeze-dried powders can well re-disperse in water. The paclitaxel (PTX) is chosen as a hydrophobic drug model and successfully encapsulate into the mPECT-2 NPs via the same method at a high solid content. The encapsulation efficiency, cytotoxicity and in vitro release of PTX-loaded NPs are investigated. The results suggest that the behavior of the drug-loaded mPECT-2 NPs prepared at a solid content of 25 wt% is similar to that of NPs prepared at a solid content of 1 wt%, which indicate that increasing solid content of polymer has no negative effect on the properties of NPs dispersion in application. In summary, the freeze-dried NPs prepared from the high solid content dispersion (≤25 wt%) has a good redispersibility and exhibits great potential in cost control of preparing NPs dispersion used as drug delivery system.

Graft copolymer nanoparticles with pH and reduction dual-induced disassemblable property for enhanced intracellular curcumin release.

Nanoparticle (NP)-assisted drug delivery systems with disassemblable behaviors in response to intracellular microenvironment are urgently demanded in systemic cancer chemotherapy for enhanced intracellular drug release. Curcumin (CUR), an effective and safe anticancer agent, was limited by its water insolubility and poor bioavailability. Herein, pH and reduction dual-induced disassemblable NPs for high loading efficiency and improved intracellular release of CUR were developed based on an acid degradable cyclic benzylidene acetal groups (CBAs)-functionalized poly(2,4,6-trimethoxybenzylidene-1,1,1-tris(hydroxymethyl)ethane methacrylate)-g-SS-poly(ethylene glycol) (PTTMA-g-SS-PEG) graft copolymer, which was readily prepared via RAFT copolymerization and coupling reaction. The NPs self-assembled from PTTMA-g-SS-PEG copolymers were stable at physiological pH, and quickly disassembled in mildly acidic and reductive environments because of the hydrolysis of CBAs in hydrophobic PTTMA core and the cleavage of disulfide-linked detachable PEG shell. PTTMA-g-SS-PEG NPs exhibited excellent CUR loading capacity with drug loading content up to 19.2% and entrapment efficiency of 96.0%. Within 20 h in vitro, less than 15.0% of CUR was released from the CUR-loaded NPs in normal physiological conditions, whereas 94.3% was released in the presence of reductive agent and mildly acidic conditions analogous to the microenvironment in endosome/lysosome and cytoplasm. Confocal fluorescence microscopies revealed that the CUR-loaded PTTMA-g-SS-PEG NPs exhibited more efficiently intracellular CUR release for EC-109 cells than that of CUR-loaded reduction-unresponsive PTTMA-g-PEG NPs and free CUR. In vitro cytotoxicity studies displayed blank PTTMA-g-SS-PEG NPs showed low toxicity at concentrations up to 1.0 mg/mL, whereas CUR-loaded PTTMA-g-SS-PEG NPs demonstrated more efficient growth inhibition toward EC-109 and HepG-2 cells than reduction-unresponsive controls and free CUR. Therefore, the above results indicated that pH and reduction dual-induced disassemblable PTTMA-g-SS-PEG NPs may have emerged as superior nanocarriers for active loading and promoted intracellular drug delivery in systemic cancer chemotherapy.