Studies on Chemical Reactivity and Electrocatalysis of Two Acylmethyl(hydroxymethyl)pyridine Ligand-Containing [Fe]-Hydrogenase Models (2-COCH2-6-HOCH2C5H3N)Fe(CO)2L (L = η1-SCOMe, η1-2-SC5H4N).

On the basis of preparation and characterization of [Fe]-H2ase models (2-COCH2-6-HOCH2C5H3N)Fe(CO)2L (A, L = η1-SCOMe; B, L = η1-2-SC5H4N), the chemical reactivities of A and B with various electrophilic and nucleophilic reagents have been investigated, systematically. Thus, when A reacted with 1 equiv of MeCOCl in the presence of Et3N in MeCN to give the η2-SCOMe-coordinated acylation product (2-COCH2-6-MeCO2CH2C5H3N)Fe(CO)2(η2-SCOMe) (1), treatment of A with excess HBF4·Et2O in MeCN gave the cationic MeCN-coordinated complex [(2-COCH2-6-HOCH2C5H3N)Fe(CO)2(MeCN)](BF4) (2). In addition, when 2 was treated with 1 equiv of 2,6-(p-4-MeC6H4)2C6H3SK or PPh3 in CH2Cl2 to give the thiophenolato- and PPh3-substituted derivatives (2-COCH2-6-HOCH2C5H3N)Fe(CO)2[2,6-(p-MeC6H4)2C6H3S] (3) and [(2-COCH2-6-HOCH2C5H3N)Fe(CO)2(PPh3)](BF4) (4), treatment of B with 1 equiv of PMe3 or P(OMe)3 in THF afforded the phosphine- and phosphite-substituted complexes (2-COCH2-6-HOCH2C5H3N)(η1-2-SC5H4N)Fe(CO)2L (5, L = PMe3; 6, L = P(OMe)3). Interestingly, in contrast to A, when B reacted with excess HBF4·Et2O in MeCN to afford the BF3 adduct [2-COCH2-6-HO(BF3)CH2C5H3N]Fe(CO)2(η1-2-SC5H4N) (7), reaction of B with 1 equiv of p-MeC6H4COCl in the presence of Et3N in MeCN gave not only the expected 2-acylmethyl-6-p-toluoyloxomethylpyridine-containing complex (2-COCH2-6-p-MeC6H4CO2CH2C5H3N)Fe(CO)2(η2-2-SC5H4N) (8), but also gave the unexpected 2-toluoyloxovinyl-6-toluoyloxomethylpyridine-containing complex (2-p-MeC6H4CO2C2H-6-p-MeC6H4CO2CH2C5H3N)Fe(CO)2(η2-2-SC5H4N) (9). While the possible pathways for the novel reactions leading to complexes 1, 2, and 7-9 are suggested, the structures of complexes B, 1-4, and 6-9 were unambiguously confirmed by X-ray crystallography. In addition, model complexes A and B have been found to be catalysts for proton reduction to H2 from TFA under CV conditions.

Effect of anionic PEGylated polypeptide on gene transfection mediated by glycolipid conjugate micelles.

To improve the gene transfection efficiency mediated by chitosan-g-stearic acid (CS) micelles, poly(ethylene glycol)-b-poly(γ-glutamic acid) (PG) was incorporated into a CS-based gene delivery system. CS/PG/pDNA complexes were prepared by ionic interaction. CS and PEGylated CS (PCS) micelles were introduced to prepare binary complexes for use as controls. CS/PG/pDNA complexes possessed similar sizes and presented as irregular spheroids in shape. The incorporation of PG into CS/pDNA complexes did not affect the ability of CS to compact pDNA and also showed a protective effect against DNase I based degradation of pDNA. Importantly, PG could increase gene transfection efficiency, which was also affected by the mixing methods used for the preparation of CS/PG/pDNA ternary complexes. The transfection efficiencies mediated by CS/PG/pDNA complexes against HEK293 and EC-1 cells reached up to 40.8% and 11.6%, respectively, which were much higher than those of CS/pDNA complexes (1.3% and 4.0%) and PCS/pDNA complexes (0.8% and 2.4%). In addition, the incorporation of PG into CS/pDNA complexes significantly enhanced cellular uptake in HEK293 and EC-1 cells and, additionally, improved endosomal escape and intracellular vector unpacking. However, the incorporation of PG reduced the cellular uptake of CS/PG/pDNA complexes in macrophages (RAW264.7 cells). It was further demonstrated that, in addition to a nonspecific charge-mediated binding to cell membranes, a γ-PGA-specific receptor-mediated pathway was involved in the internalization of CS/PG/pDNA complexes. These results indicated that PG played multiple important roles in enhancing the transfection efficiency of CS/PG/pDNA complexes.

High tolerated paclitaxel nano-formulation delivered by poly (lactic-co-glycolic acid)-g-dextran micelles to efficient cancer therapy.

The amphiphilic graft copolymer poly (lactic-co-glycolic acid)-g-dextran (Dex-PLGA) was successfully synthesized to fabricate micelles for the delivery of paclitaxel with low critical micelle concentration (CMC). The sizes of paclitaxel-loaded Dex-PLGA (Dex-PLGA/PTX) micelles were kept below 100nm with a relatively narrow size distribution. This novel PTX nano-formulation was found to exhibit slightly stronger in vitro cytotoxicity against SKOV-3, OVCAR-8 and MCF-7 cells with Taxol®. However, it could overcome the drug resistance of multi-drug resistant human breast carcinoma cells (MCF-7/Adr cells). The maximum tolerated dose (MTD) of Dex-PLGA/PTX after a single dose was more than 200mg PTX/kg, which were 8-fold higher than that of Paclitaxel Injection. The in vivo antitumor activity results indicated that Dex-PLGA/PTX micelles treatments effectively suppressed the tumor growth and highly reduced the toxicity against animals than Taxol® and could eliminate the SKOV-3 tumor by highly increasing the drug dose. FROM THE CLINICAL EDITOR: Chemotherapy for cancer has always been hampered the toxic side effect of the drugs. Nanotechnology has helped to produce various drug delivery systems to minimize these side effects. In this article, the authors designed dextran-based micelles loaded with paclitaxel. They showed effective anti-tumor activity in both in vitro and in vivo experiments with significant lower systemic toxicity.

Transport pathways of solid lipid nanoparticles across Madin-Darby canine kidney epithelial cell monolayer.

An understanding of drug delivery system transport across epithelial cell monolayer is very important for improving the absorption and bioavailability of the drug payload. The mechanisms of epithelial cell monolayer transport for various nanocarriers may differ significantly due to their variable components, surface properties, or diameter. Solid lipid nanoparticles (SLNs), conventionally formed by lipid materials, have gained increasing attention in recent years due to their excellent biocompatibility and high oral bioavailability. However, there have been few reports about the mechanisms of SLNs transport across epithelial cell monolayer. In this study, the molecular mechanisms utilized by SLNs of approximately 100 nm in diameter crossing intestinal epithelial monolayer were carefully studied using a simulative intestinal epithelial monolayer formed by Madin-Darby canine kidney (MDCK) epithelial cells. The results demonstrated that SLNs transportation did not induce a significant change on tight junction structure. We found that the endocytosis of SLNs into the epithelial cells was energy-dependent and was significantly greater than nanoparticle exocytosis. The endocytosis of SLNs was found to be rarely mediated via macropinocytosis, as confirmed by the addition of 5-(N-ethyl-N-isopropyl)amiloride (EIPA) as an inhibitory agent, and mainly depended on lipid raft/caveolae- and clathrin-mediated pathways. After SLNs was internalized into MDCK cells, lysosome was one of the main destinations for these nanoparticles. The exocytosis study indicated that the endoplasmic reticulum, Golgi complex, and microtubules played important roles in the transport of SLNs out of MDCK cells. The transcytosis study indicated that only approximately 2.5% of the total SLNs was transported from the apical side to the basolateral side. For SLNs transportation in MDCK cell monolayer, greater transport (approximately 4-fold) was observed to the apical side than to the basolateral side. Our findings may present a more comprehensive understanding on the transport of SLNs across epithelial cell monolayer.

Improved transport and absorption through gastrointestinal tract by PEGylated solid lipid nanoparticles.

The aim of the present study was to evaluate the potential of PEGylated solid lipid nanoparticle (pSLN) as mucus penetrating particles (MPP) for oral delivery across gastrointestinal mucus. The SLN was prepared by an aqueous solvent diffusion method, subsequently modified with PEG2000-stearic acid (PEG2000-SA) as hydrophilic groups. Surface properties, cytotoxicity, cellular uptake, and transport across Caco-2/HT29 coculture cell monolayers, intestinal absorption, and pharmacokinetics of pSLN were studied compared with that of SLN. Quantitative cellular uptake showed that the internalization of SLN and pSLN was an active transfer process, which would be restrained by several inhibitors of cell activity. Compared with SLN, the permeation ability of pSLN decreased through Caco-2 cell monolayer while it increased through a mucus-secreting Caco-2/HT29 coculture cell monolayer, which indicated that the mucus layer has a significant impact on determining the efficiency of oral nanoformulations. In addition to increasing permeation ability, the stability of the nanoparticles in simulated intestinal fluids was also increased by the PEGylation. Moreover, in vitro everted gut sac technique and the ligated intestinal loops model in vivo also demonstrated that pSLN can rapidly penetrate mucus secretions, whereas the SLN were strongly trapped by highly viscoelastic mucus barriers. The pharmacokinetic studies presented that pSLN exhibited improved absorption efficiency and prolonged blood circulation times with a 1.99-fold higher relative bioavailability compared with SLN. In conclusion, PEGylated solid lipid nanoparticles had advantages in enhancing the bioavailability of oral administration.

Effect of proteins with different isoelectric points on the gene transfection efficiency mediated by stearic acid grafted chitosan oligosaccharide micelles.

A stearic acid-grafted chitosan oligosaccharide (CS-SA) micelle has been demonstrated as an effective gene carrier in vitro and in vivo. Although being advantageous for DNA package, protection, and excellent cellular internalization, a CS-SA based delivery system may lead to difficulties in the dissociation of polymer/DNA complexes in intracells. In this research, bovine serum albumin (BSA) with a different isoelectric point value (4.7, 6.0 and 9.3) was synthesized and incorporated into a CS-SA based gene delivery system. CS-SA/DNA binary complexes and CS-SA/BSA/DNA ternary complexes were then prepared and characterized. The binding ability of the CS-SA vector with DNA was not affected by the incorporation of BSA. However, referring to the transfection activity, the BSA of different isoelectric point value (pI) had a distinct influence on the CS-SA/BSA/DNA complexes. CS-SA/BSA(4.7)/DNA and CS-SA/BSA(6.0)/DNA complexes had better transfection efficiency than binary complexes, especially CS-SA/BSA(4.7)/DNA complexes which showed the highest transfection efficiency. On the contrary, CS-SA/BSA(9.3)/DNA complexes had undesirable performances. Interestingly, the incorporation of BSA(4.7) in CS-SA/DNA complexes significantly enhanced the dissociation of polymer/DNA complexes and improved the release of DNA intracellular without influencing their cellular uptake. The aforementioned results indicated that the acid group in protein played an important role in enhancing the transfection efficiency of CS/BSA/DNA complexes, and the study provided guidelines in the design of an efficient vector for DNA transfection.

pH triggered doxorubicin delivery of PEGylated glycolipid conjugate micelles for tumor targeting therapy.

The main objective of this study was aimed at tumor microenvironment-responsive vesicle for targeting delivery of the anticancer drug, doxorubicin (DOX). A glucolipid-like conjugate (CS) was synthesized by the chemical reaction between chitosan and stearic acid, and polyethylene glycol (PEG) was then conjugated with CS via a pH-responsive cis-aconityl linkage to produce acid-sensitive PEGylated CS conjugates (PCCS). The conjugates with a critical micelle concentration (CMC) of 181.8 µg/mL could form micelles in aqueous phase, and presented excellent DOX loading capacity with a drug encapsulation efficiency up to 87.6%. Moreover, the PCCS micelles showed a weakly acid-triggered PEG cleavage manner. In vitro drug release from DOX-loaded PCCS micelles indicated a relatively faster DOX release in weakly acidic environments (pH 5.0 and 6.5). The CS micelles had excellent cellular uptake ability, which could be significantly reduced by the PEGylation. However, the cellular uptake ability of PCCS was enhanced comparing with insensitive PEGylated CS (PCS) micelles in weakly acidic condition imitating tumor tissue. Taking PCS micelles as a comparative group, the PCCS drug delivery system was demonstrated to show much more accumulation in tumor tissue, followed by a relatively better performance in antitumor activity together with a security benefit on xenograft tumor model.

In vitro antitumour activity of stearic acid-g-chitosan oligosaccharide polymeric micelles loading podophyllotoxin.

Development of successful formulations for poorly water-soluble drugs remains a longstanding critical and challenging issue in cancer therapy. The stearic acid-g-chitosan oligosaccharide (CSO-SA) micelles have been presented as potential candidates for intracellular antitumour agent delivery carrier. Herein, podophyllotoxin (PPT) loaded CSO-SA micelles (CSO-SA/PPT) were prepared by a dialysis method. The drug encapsulation efficiency could reach a higher level, the micellar size and the zeta potential increased with increasing charged amounts of drug. The cumulative release percentage of PPT drug from micelles enhanced with decreasing PPT content in the micelles. The cytotoxicities of CSO-SA/PPT micelles against human breast carcinoma (MCF-7) cells, human lung cancer cells (A549) and human hepatoma cell line (Bel-7402) were higher than that of free PPT formulation. The higher cytotoxicities were due to the faster PPT transport into tumour cells mediated by CSO-SA micelles. Overall, CSO-SA micelles might be a promising carrier for PPT delivery in cancer therapy.

Near-Infrared Responsive Membrane Nanovesicles Amplify Homologous Targeting Delivery of Anti-PD Immunotherapy against Metastatic Tumors.

The major obstacles of anti-PD therapy in metastatic tumors are limited drug delivery in primary tumors and metastatic foci, and the lack of tumor-infiltrating lymphocytes (TILs). Here, the authors constructed a novel cellular membrane nanovesicles platform (M/IR NPs) based on homologous targeting and near-infrared (NIR) responsive release strategy to potentiate PD-1/PD-L1 blockade therapy against metastatic tumors. In tumor-bearing mice, biomimetic M/IR NPs targeted both primary tumors and their lung metastases. Upon laser irradiation, M/IR NPs reduced cancer-associated fibroblasts (CAFs) in tumor microenvironment, thus increasing the penetration of TILs. When shed from homologous tumor cell membranes, positively charged nanoparticles (IR NPs) core can capture released tumor-associated antigens, thereby enhancing the antigen-presenting ability of DCs to activate cytotoxic T lymphocytes. When the photothermal conversion temperature under NIR-laser is higher than 42 °C, M/IR NPs initiated the rupture of cell membranes and the responsive release of PD-1/PD-L1 inhibitor BMS, which significantly attenuated tumor-associated immunosuppression and synergistically induced T cellular immunity to inhibit the tumor growth and metastasis. Overall, biomimetic M/IR NPs can improve the targeting and therapeutic efficacy of anti-PD therapy in primary tumors and metastases, opening up a new avenue for the diagnosis and treatment of metastatic tumors in the future.

Stearic acid-g-chitosan polymeric micelle for oral drug delivery: in vitro transport and in vivo absorption.

Stearic acid-g-chitosan (low molecular weight chitosan CS-SA) with different amino-substituted degrees was synthesized and evaluated as an oral delivery vehicle in this paper. Synthesized CS-SA with 4.47%, 24.36% and 40.36% amino-substituted degree (SD) could form micelles by self-aggregation in aqueous medium. The critical micelle concentration (CMC) ranged from about 0.16 to 0.25 mg/mL, which decreased with the increased SD of CS-SA. The CS-SA micelles had 33.4-130.9 nm size and 22.9- 48.4 mV zeta potential. CS-SA with higher SD had the smaller size and the higher zeta potential. The permeability and possible transport route of CS-SA micelles across the gastrointestinal tract was investigated by in vitro model Caco-2 cells. The results exhibited that the CS-SA micelles had good permeability, and the permeability enhanced with increasing SD of the CS-SA. The transport of the micelles showed energy, pH and concentration dependent transcytosis process, mainly through macropinocytosis and partly via fluid-phase transcytosis and caveolar route. The reversible decrease in transepithelial electrical resistance (TEER) by treatment of micelles suggested that paracellular transport pathway was another route of the micelles crossing the gastrointestinal tract. Using doxorubicin (DOX) as a model drug, the permeation results further demonstrated that the DOX transport mediated by CS-SA micelles could avoid efflux via P-glycoprotein. In vivo study demonstrated that the micelles could significantly improve the bioavailability of encapsulated drug. The results presented that the CS-SA with higher SD was a promising vehicle for oral drugs.

Thermal-sensitive lipid nanoparticles potentiate anti-PD therapy through enhancing drug penetration and T lymphocytes infiltration in metastatic tumor.

The response rate of anti-PD therapy in most cancer patients remains low. Therapeutic drug and tumor-infiltrating lymphocytes (TILs) are usually obstructed by the stromal region within tumor microenvironment (TME) rather than distributed around tumor cells, thus unable to induce the immune response of cytotoxic T cells. Here, we constructed the cationic thermosensitive lipid nanoparticles IR780/DPPC/BMS by introducing cationic NIR photosensitizer IR-780 iodide (IR780) modified lipid components, thermosensitive lipid DPPC and PD-1/PD-L1 inhibitor BMS202 (BMS). Upon laser irradiation, IR780/DPPC/BMS penetrated into deep tumor, and reduced cancer-associated fibroblasts (CAFs) around tumor cells to remodel the spatial distribution of TILs in TME. Interestingly, the cationic IR780/DPPC/BMS could capture released tumor-associated antigens (TAAs), thereby enhancing the antigen-presenting ability of DCs to activate cytotoxic T lymphocytes. Moreover, IR780/DPPC/BMS initiated gel-liquid crystal phase transition under laser irradiation, accelerating the disintegration of lipid bilayer structure and leading to the responsive release of BMS, which would reverse the tumor immunosuppression state by blocking PD-1/PD-L1 pathway for a long term. This combination treatment can synergistically exert the antitumor immune response and inhibit the tumor growth and metastasis.

Quercetin Covalently Linked Lipid Nanoparticles: Multifaceted Killing Effect on Tumor Cells.

The encapsulation of hydrophobic drugs is a problem that many researchers are working on. The goal of this study is to achieve the delivery of hydrophobic drugs by means of prodrugs and nanoformulations for a stronger tumor cell-killing effect and explore related killing mechanisms. Lipophilic quercetin (Qu) was covalently linked to glyceryl caprylate-caprate (Gcc) via disulfide bonds-containing 3,3'-dithiodipropionic acid (DTPA) to synthesize novel lipid Qu-SS-Gcc. Qu-SS-Gcc lipid nanoparticles (Qu-SS-Gcc LNPs) were fabricated using the solvent diffusion technique. The intracellular release of Qu by cleavage of nanocarriers was determined by liquid chromatography and compared with the uptake of free Qu. Detection methods, such as fluorescent quantitation, flow cytometry, and western blot were applied to explore the action mechanism induced by Qu. It was revealed that Qu-SS-Gcc LNPs could be cleaved by the high concentrations of reduction molecules in MCF-7/ADR (human multidrug-resistant breast cancer) cells, followed by the release of Qu. The intracellular Qu content produced by dissociation of Qu-SS-Gcc LNPs was higher than that produced by internalization of free Qu. The resulting release of Qu exerted superior cell-killing effects on MCF-7/ADR cells, such as P-gp inhibition by binding to P-gp binding sites, blocking the cell cycle in the G2 phase, and causing cell apoptosis and autophagy. Moreover, it was revealed autophagy triggered by a low concentration of Qu-SS-Gcc LNPs was beneficial to cell survival, while at a higher concentration, it acted as a cell killer. Qu-SS-Gcc LNPs can realize massive accumulation of Qu in tumor cells and exert a multifaceted killing effect on tumor cells, which is a reference for the delivery of hydrophobic drugs.

Inhibition of chemotherapy-related breast tumor EMT by application of redox-sensitive siRNA delivery system CSO-ss-SA/siRNA along with doxorubicin treatment.

Metastasis is one of the main reasons causing death in cancer patients. It was reported that chemotherapy might induce metastasis. In order to uncover the mechanism of chemotherapy-induced metastasis and find solutions to inhibit treatment-induced metastasis, the relationship between epithelial-mesenchymal transition (EMT) and doxorubicin (DOX) treatment was investigated and a redox-sensitive small interfering RNA (siRNA) delivery system was designed. DOX-related reactive oxygen species (ROS) were found to be responsible for the invasiveness of tumor cells in vitro, causing enhanced EMT and cytoskeleton reconstruction regulated by Ras-related C3 botulinum toxin substrate 1 (RAC1). In order to decrease RAC1, a redox-sensitive glycolipid drug delivery system (chitosan-ss-stearylamine conjugate (CSO-ss-SA)) was designed to carry siRNA, forming a gene delivery system (CSO-ss-SA/siRNA) downregulating RAC1. CSO-ss-SA/siRNA exhibited an enhanced redox sensitivity compared to nonresponsive complexes in 10 mmol/L glutathione (GSH) and showed a significant safety. CSO-ss-SA/siRNA could effectively transmit siRNA into tumor cells, reducing the expression of RAC1 protein by 38.2% and decreasing the number of tumor-induced invasion cells by 42.5%. When combined with DOX, CSO-ss-SA/siRNA remarkably inhibited the chemotherapy-induced EMT in vivo and enhanced therapeutic efficiency. The present study indicates that RAC1 protein is a key regulator of chemotherapy-induced EMT and CSO-ss-SA/siRNA silencing RAC1 could efficiently decrease the tumor metastasis risk after chemotherapy.

Chitosan-modified lipid nanodrug delivery system for the targeted and responsive treatment of ulcerative colitis.

Targeted and sensitive drug release at the colitis site is critical for the effective therapy of ulcerative colitis and reduction of side effects from the drug. Herein, we used 3,3'-dithiodipropionic acid (DTPA) to covalently link quercetin (Qu) and glyceryl caprylate-caprate (Gcc) via ester bonds to prepare Qu-SS-Gcc lipid nanoparticles (Qu-SS-Gcc LNPs). Dexamethasone (Dex) was used as a model drug, and chitosan (CSO) was modified on the surface of Qu-SS-Gcc LNPs to obtain CSO-modified Dex-loaded Qu-SS-Gcc LNPs (CSO/Dex/LNPs). The encapsulation efficiency and drug loading of CSO/Dex/LNPs were 93.1 % and 8.1 %, respectively. The in vitro release results showed that CSO/Dex/LNPs had esterase-responsive characteristics and could release the drug rapidly in esterase-containing artificial intestinal fluid. A human colorectal adenocarcinoma cell (Caco-2) monolayer was used as the intestinal cell barrier model. Transmembrane resistance measurements and permeation experiments showed that CSO/Dex/LNPs had a protective effect on the lipopolysaccharide (LPS)-stimulated Caco-2 cell monolayer and increased the expression of E-cadherin in LPS-stimulated Caco-2 cells. Moreover, CSO/Dex/LNPs could significantly reduce the expression of the inflammatory factors TNF-α, IL-6 and NO in LPS-stimulated RAW 264.7 cells. The ulcerative colitis mouse model was constructed by using C57BL/6 mice. The in vivo distribution results showed that CSO/Dex/LNPs had colon-targeting effects and strong retention ability in the colons of mice with colitis. The results also showed that CSO/Dex/LNPs had better anti-inflammatory effects than free Dex, which could reduce colonic atrophy, reduce histomorphological changes and increase the expression of E-cadherin in the colon. Furthermore, the expression levels of TNF-α, IL-6 and NO in the CSO/Dex/LNP-treated group were 37.4 %, 35.5 % and 33.2 % of those in mice with colitis, respectively.

A novel biocompatible, simvastatin-loaded, bone-targeting lipid nanocarrier for treating osteoporosis more effectively.

An insufficient drug concentration at the target site and drug efflux resulting in poor efficacy are recognized as important obstacles in osteoporosis treatment. Simvastatin (SIM), which can treat osteoporosis by promoting osteoblast differentiation and mineralization through the bone morphogenetic proteins (BMP)-Smad signaling pathway, has lower bioavailability, and less bone tissue distribution. Herein, novel lipid nanoparticles (LNPs) delivering SIM (SIM/LNPs) for osteoporosis therapy were developed with aspartic oligopeptide (ASP n , here ASP6)-based bone-targeting moieties grafted to the nanoparticles (SIM/ASP6-LNPs) in an attempt to increase the concentration of SIM in bones with a relatively low dose to minimize adverse effects. In vivo experiments indicated that the ASP6-LNPs exhibited ideal bone-targeting characteristics, and in vitro cell evaluation experiments showed LNPs have good biocompatibility with MC3T3-E1 cells. The cell mineralization experiment revealed that the SIM-loaded LNPs induced osteoblast differentiation and the formation of mineralized nodules in MC3T3-E1 cells, achieving the same efficacy as that of SIM. Pharmacodynamic experiments revealed that SIM/ASP6-LNPs improved the efficacy of SIM on the recovery of bone mineral density when compared to SIM/LNPs or to SIM alone. Therefore, SIM/ASP6-LNPs may represent a potential bone-targeting drug delivery system (DDS) that contributes to the development of a novel osteoporosis treatment.

Correction: A novel biocompatible, simvastatin-loaded, bone-targeting lipid nanocarrier for treating osteoporosis more effectively.

[This corrects the article DOI: 10.1039/D0RA00685H.].

Coadministration of glycolipid-like micelles loading cytotoxic drug with different action site for efficient cancer chemotherapy.

To reduce the side effects and drug resistance in cancer chemotherapy, we have examined the in vitro efficacy of the combination of paclitaxel (PTX) and doxorubicin (DOX) loaded in nanosized polymeric micelles with glycolipid-like structure, which formed by lipid grafted chitosan. The cytotoxicities of PTX and DOX, either as single agents or in combination, were examined using drug sensitive tumor cells and drug resistant cells. It was found that the 50% inhibition of cellular growth (IC(50)) of PTX and DOX in micelles against drug sensitive cells was lowered about 20-fold and 4-7-fold compared to that of Taxol and DOX solution, respectively. The IC(50) of PTX and DOX in micelles against drug resistant cells was lowered more significantly, and no clear difference was found between drug sensitive and drug resistant cells. The coadministration of PTX and DOX in micelles showed a more conspicuous effect than that of micelles loaded with a single drug. The micelles presented excellent internalization to cancer cells, which results in increased intracellular accumulation of PTX and DOX in its molecular-target site. The coadministration of glycolipid-like micelles loaded with different cytotoxic drugs indicated synergistic effects for drug sensitive cells and drug resistant cells.

Redox-responsive chitosan oligosaccharide-SS-Octadecylamine polymeric carrier for efficient anti-Hepatitis B Virus gene therapy.

DrzBC and DrzBS (10-23 DNAzyme) could block the expression of HBV e- and s- gene respectively. But the application of 10-23 DNAzyme was limited owing to the lack of appropriate delivery vehicles. Chitosan oligosaccharide-SS-Octadecylamine (CSSO), a redox-responsive nano-sized polymeric carrier, could self-aggregate and bind with DNA by electrostatic interaction at proper mass ratio. Compared with the traditional commercial carrier Lipo2000, CSSO exhibited lower cytotoxicity, efficient cellular uptake by targeting cells, and rapidly DNA released in cytoplasm after escaping from endosomes. Including the same DNA concentration, Lipo2000/(DrzBC or DrzBS) showed maximum inhibitory rate on HBeAg (47.29 ±â€¯1.86%) and HBsAg (33.58 ±â€¯0.72%) secretion after 48 h incubation, and then both decreased. In contrast, HBeAg secretion inhibition by CSSO/DrzBC and HBsAg secretion inhibition by CSSO/DrzBS were up to 73.86 ±â€¯1.77% and 67.80 ±â€¯2.51% at 48 h, and further increased to 83.83 ±â€¯2.34% and 76.79 ±â€¯2.18% at 72 h, respectively. CSSO is a promising redox-responsive polymeric carrier for efficient anti-Hepatitis B Virus gene therapy.

Cellular uptake and cytotoxicity of shell crosslinked stearic acid-grafted chitosan oligosaccharide micelles encapsulating doxorubicin.

Stearic acid-grafted chitosan oligosaccharide (CSO-SA) with 3.48% amino-substituted degree (SD%) was synthesized by coupling reaction. The CSO-SA could self-aggregate to form micelle with a critical micelle concentration (CMC) at 0.035 mg/mL in the aqueous phase. The CSO-SA self-aggregate micelles indicated spatial structure with multi-hydrophobic core. One CSO-SA chain could form 2.8 hydrophobic cores. Cellular uptakes of CSO-SA micelles by using A549, LLC, and SKOV3 cells as model tumor cell lines showed the faster cellular internalization of CSO-SA micelles, and the cellular uptakes on the LLC and SKOV3 cells were higher than that on the A549 cells. Doxorubicin (DOX) was then used as a model drug to incorporate into CSO-SA micelles. To reduce the initial burst drug release from CSO-SA micelles loading DOX (CSO-SA/DOX), the shell of CSO-SA micelles was crosslinked by glutaraldehyde. The shell crosslinking of CSO-SA micelles reduced the micelle size and surface potential, but it did not significantly affect the cellular uptake and drug encapsulation efficiency of CSO-SA micelles. The cellular inhibition experiments demonstrated that the cytotoxicity of DOX was increased by the encapsulation of CSO-SA micelles. CSO-SA/DOX displayed the best antitumor efficacy in SKOV3 cell line due to the higher cellular uptake percentage of CSO-SA micelles and the lower sensitivity of free drug to the cells. The cytotoxicities of shell crosslinked CSO-SA/DOX were highly enhanced in all cell lines than those of unmodified CSO-SA/DOX.

PEGylated chitosan-based polymer micelle as an intracellular delivery carrier for anti-tumor targeting therapy.

Stearic acid-grafted chitosan oligosaccharide (CSO-SA) micelles presented a potential candidate for intracellular drug delivery carrier due to its special spatial structure. In this article, CSO-SA was further modified by polyethylene glycol (PEG). The physicochemical properties of PEGylated CSO-SA (PEG-CSO-SA) micelles were characterized. After PEGylation, the critical micelle concentration (CMC) of PEG-CSO-SA had no significant change; the micelle size increased; and the zeta potential decreased. The cellular uptake of CSO-SA micelles before and after PEGylation in macrophage RAW264.7, immortalized rat liver cells BRL-3A and human liver tumor cells HepG2 was studied. About 58.4+/-0.63% of CSO-SA micelles were uptaked by RAW264.7 in 24h, however, only 17.7+/-0.94% of PEG-CSO-SA micelles were internalized into RAW264.7 after the CSO-SA was modified with PEG in five molar times. Meanwhile, there were no changes in the uptake after PEGylation of CSO-SA in BRL-3A and HepG2. Using mitomycin C as a model drug, the in vitro anti-tumor activities of the drug loaded in the micelles were investigated. The 50% cellular growth inhibition (IC(50)) of the drug decreased from 1.97+/-0.2 to 0.13+/-0.02mug/mL after mitomycin C was loaded into CSO-SA micelles, and the IC(50) value of the drug had no obvious change when the CSO-SA was modified by PEG.