pH/enzyme dual sensitive and nucleus-targeting dendrimer nanoparticles to enhance the antitumour activity of doxorubicin.

Direct delivery of drugs into the nucleus is a promising nanotechnology therapy, since the nucleus is one of the most important organelles controlling cell proliferation and apoptosis. Here, we report a nucleus-targeting nanocarrier for nuclear drug delivery using a pH/enzyme dual sensitive strategy. The specific ligand PGM (PKKKRKV-GFLG-Mp), composed of nuclear localization sequence (PKKKRKV), enzyme-sensitive tetrapeptide (Gly-Phe-Leu-Gly, GFLG), and pH-sensitive molecules morpholine (Mp), was modified on poly (amidoamine) (PAMAM) by maleimide active polyethylene glycol ester (NHS-PEG-MAL) to form PAMAM-PEG-PGM. Doxorubicin (DOX) was loaded into the cavity of PAMAM to prepare DOX/PAMAM-PEG-PGM. In vitro release study suggested DOX release from DOX/PAMAM-PEG-PGM nanoparticles followed pH and enzyme-triggered manner. In vitro studies showed DOX/PAMAM-PEG-PGM nanoparticles could not only promote cell internalization through the charge switching of morpholine, but also achieve nuclear internalization by the mediation of composite formed by NLS and importin α/ß receptor. Further, employing H22 tumour-bearing BALB/c mice as a model, the systemic distribution and anticancer effects of nanoparticles were studied in vivo. The results indicated the nanoparticles could preferentially accumulate in the tumour site in vivo, and the tumour inhibition rate was 88.47%. In short, the nanoparticles developed could be promising in application to nucleus-targeting therapy to enhance antitumour activity.

Size-shrinkable and protein kinase Cα-recognizable nanoparticles for deep tumor penetration and cellular internalization.

In the present study, the three functions, including enhanced permeability and retention (EPR) effect, deep penetration within tumor, and receptor-mediated endocytosis, were integrated into a single platform in order to improve antitumor efficiency. A novel nanoparticle (dendrigraft poly-L-lysine@glycyrrhetinic acid@cyclohexane dicarboxylic anhydride@doxorubicin@ hyaluronic acid composite) has been successfully developed and was denoted as DGL-GA-CDA-DOX-HA. The transmission electron microscope (TEM), dynamic light scattering (DLS), polymer dispersity index (PDI), fourier transform infrared spectrometer (FTIR), and zeta potentials were used to characterize the physicochemical properties of the nanoparticles. According to the results of TEM and DLS, the DGL-GA-CDA-DOX-HA nanoparticles could be rapidly degraded with a size shrink from 182.5 nm to 47.7 nm by hyaluronidase (HAase) added in the medium. The loading amount of DOX reached 252.03 ± 36.38 mg/g for DGL-GA-CDA-DOX nanoparticles. When the nanoparticles were in a medium with HAase at pH 5.0, the drug quickly released. However, when the nanoparticles were exposed to a medium without HAase at pH 5.0, or a neutral medium containing HAase, drug release slowed down. The modification of GA on nanoparticles significantly enhanced their affinity and cytotoxicity to hepatocellular carcinoma HepG2 cells. The study showed that the penetrability of DGL-GA-CDA-DOX and DGL-GA-CDA DOX-HA nanoparticles pre-degraded by HAase in vitro multicellular tumor spheroids were always better than that of DGL-GA-CDA-DOX-HA nanoparticles untreated by HAase. The imaging in vivo and ex vivo exhibited that DGL-GA-CDA-DOX-HA nanoparticles could preferentially accumulate in the tumor site. Correspondingly, the DGL-GA-CDA-DOX-HA displayed the preferable antitumor efficiency to other experimental groups in H22 tumor-bearing mice, with a tumor inhibition rate of 71.6%. In short, these results suggested that DGL-GA-CDA-DOX-HA nanoparticles could promote therapeutic effects by modulating particle size and GA receptor-mediated endocytosis.

pH-Sensitive nanoparticles as smart carriers for selective intracellular drug delivery to tumor.

Herein, a smart pH-sensitive nanoparticle (DGL-PEG-Tat-KK-DMA-DOX) was prepared to achieve the selective intracellular drug delivery. In this nanoparticle, a PEG-grafted cell penetrating peptide (PEG-Tat-KK) was designed and acted as the cell penetrating segment. By introducing the pH-sensitive amide bonds between the peptide and blocking agent (2,3-dimethylmaleic anhydride, DMA), the controllable moiety (PEG-Tat-KK-DMA) endowed the nanoparticle with a charge-switchable shell and temporarily blocked penetrating function, thus improving the specific internalization. Besides, dendrigraft poly-L-lysine (DGL) used as the skeleton can greatly improve the drug loading because of the highly dendritic framework. Under the stimuli of acidic pH, this nanoparticle exhibited a remarkable charge-switchable property. The drug release showed an expected behavior with little release in the neutral pH media but relatively fast release in the acidic media. The in vitro experiments revealed that the cellular uptake and cytotoxicity were significantly enhanced after the pH was decreased. In vivo biodistribution and antitumor research indicated that the nanoparticle had noteworthy specificity and antitumor efficacy with a tumor inhibition rate of 79.7%. These results verified this nanoparticle could efficiently improve the selective intracellular delivery and possessed a great potential in tumor treatment.

Heterogeneous dimer peptide-conjugated polylysine dendrimer-Fe3O4 composite as a novel nanoscale molecular probe for early diagnosis and therapy in hepatocellular carcinoma.

A novel nanoscale molecular probe is formulated in order to reduce toxicity and side effects of antitumor drug doxorubicin (DOX) in normal tissues and to enhance the detection sensitivity during early imaging diagnosis. The mechanism involves a specific targeting of Arg-Gly-Asp peptide (RGD)-GX1 heterogeneous dimer peptide-conjugated dendrigraft poly-l-lysine (DGL)-magnetic nanoparticle (MNP) composite by αvß3-integrin/vasculature endothelium receptor-mediated synergetic effect. The physicochemical properties of the nanoprobe were characterized by using transmission electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, dynamic light scattering (DLS), and vibrating sample magnetometer. The average diameter of the resulting MNP-DGL-RGD-GX1-DOX nanoparticles (NPs) was ~150-160 nm by DLS under simulate physiological medium. In the present experimental system, the loading amount of DOX on NPs accounted for 414.4 mg/g for MNP-DGL-RGD-GX1-DOX. The results of cytotoxicity, flow cytometry, and cellular uptake consistently indicated that the MNP-DGL-RGD-GX1-DOX NPs were inclined to target HepG2 cells in selected three kinds of cells. In vitro exploration of molecular mechanism revealed that cell apoptosis was associated with the overexpression of Fas protein and the significant activation of caspase-3. In vivo magnetic resonance imaging and biodistribution study showed that the MNP-DGL-RGD-GX1-DOX formulation had high affinity to the tumor tissue, leading to more aggregation of NPs in the tumor. In vivo antitumor efficacy research verified that MNP-DGL-RGD-GX1-DOX NPs possessed significant antitumor activity and the tumor inhibitory rate reached 78.5%. These results suggested that NPs could be promising in application to early diagnosis and therapy in hepatocellular carcinoma as a specific nanoprobe.

Surface charge-switchable polymeric magnetic nanoparticles for the controlled release of anticancer drug.

We develop paclitaxel (PTX) and magnetic nanoparticles (MNPs) coencapsulated, surface charge-switchable, thermosensitive poly(d,l-lactic-co-glycolic acid)-l-lysine-d-galactose (PTX-MNP-PLGA-Lys-Gal) NPs for the controlled release of the anticancer drug. The novel dual signal-responsive nanovehicle is formulated to shield off target at pH 7.4 but bind avidly to tumor cells in acidity, alleviating toxicity and side effects of the drug to normal tissues. The mechanism involves pH-sensitive NPs surface charge switching by the deblocking process of galactose molecules followed by protonation of ε-NH2 in lysine residue at acidic pH. Magnetic hyperthermia under near infrared (NIR) irradiation induced the contraction of PTX-MNP-PLGA-Lys-Gal NPs and, in turn, triggered burst release of PTX. Transmission electron microscopy (TEM), fluorescence microscope analyses, Fourier transform infrared (FTIR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), dynamic light scattering (DLS), and ξ-potential analyses were performed to characterize physicochemical properties of the as-prepared NPs. The size range of the globule PTX-MNP-PLGA-Lys-Gal NPs after being prescreened was from 130 to 150 nm under simulated physiological medium. The high encapsulation efficiencies of MNPs and PTX were obtained, reaching 85 and 78 wt % for PTX-MNP-PLGA-Lys-Gal NPs, respectively. The tumor inhibitory rate of 78.8% reflected that the resulting NPs could be promising to treat cancer by specific binding and targeting release drug to tumor.

cRGD-functionalized polymeric magnetic nanoparticles as a dual-drug delivery system for safe targeted cancer therapy.

In this paper we give a method of integrated treatment for cancer and drug-induced complications in the process of cancer therapy through dual-drug delivery system (DDDS). Two hydrophilic drugs, doxorubicin (an antitumor drug) and verapamil (an antiangiocardiopathy drug) combined preliminarily with chitosan shell coated on magnetic nanoparticles (MNPs), followed by entrapping into the PLGA nanoparticles. Further modification was conducted by conjugating tumor-targeting ligand, cyclo(Arg-Gly-Asp-D-Phe-Lys) (c(RGDfK)) peptide, onto the end carboxyl groups on the PLGA-NPs. The size of the resulting cRGD-DOX/VER-MNP-PLGA NPs was approximately 144nm under simulate physiological environment. Under present experiment condition, the entrapment efficiencies of DOX and VER were approximately 74.8 and 53.2wt% for cRGD-DOX/VER-MNP-PLGA NPs. This paper contains interesting pilot data such as NIR-triggered drug release, in vivo drug distribution studies and whole-mouse optical imaging. Histopathological examinations and electrocardiogram comparison demonstrated that the intelligent DDDS could markedly inhibit the growth of tumor and potentially offer an approach for safe cancer therapy.

Luminescent/magnetic hybrid nanoparticles with folate-conjugated peptide composites for tumor-targeted drug delivery.

We developed a novel chitosan-based luminescent/magnetic hybrid nanoparticles with folate-conjugated tetrapeptide composites (CLMNPs-tetrapeptide-FA) by conjugation in situ. First, chitosan, CdTe quantum dots (QDs), and superparamagnetic iron oxide were directly gelled into ternary hybrid nanogels. Subsequently, tetrapeptides (GFFG and LGPV) and folate were conjugated orderly into the hybrid nanoparticles. The morphology, composition, and properties of the as-prepared copolymers have also been characterized and determined using TEM, EDX, XRD, FTIR spectra, DLS, fluorescence spectroscopy, VSM, and fluorescence microscopy imaging studies. The size range of the end product CLMNPs-tetrapeptide-FA copolymers was from 150 to 190 nm under simulated physiological environment. In vivo, the experimental results of magnetic accumulation showed that the copolymers could be trapped in the tumor tissue under magnetic guidance. Under the present experimental conditions, the loading efficiencies of CPT were approximately 8.6 wt % for CLMNPs-GFFG-FA and 1.1 wt % for CLMNPs-LGPV-FA, respectively. The CPT cumulative release under dialysis condition mainly occurred for the first 28 h, and could reach 55% at pH 5.3 and 46% at pH 7.4 from CPT-loaded CLMNPs-GFFG-FA, and 69% at pH 5.3 and 57% at pH 7.4 from CPT-loaded CLMNPs-LGPV-FA within 28 h, respectively. The hemolysis percentages (<2%) and coagulation properties of blank and CPT-loaded copolymers were within the scope of safe values. Compared to free CPT, the CPT-loaded CLMNPs-tetrapeptide-FA copolymers showed specific targeting to A549 cells in vitro. More than 75% viability in L02 cells were seen in CLMNPs-GFFG-FA and CLMNPs-LGPV-FA copolymer concentration of 500 µg/mL, respectively. It was found that the two kinds of copolymers were transported into the A549 cells by a folate-receptor-mediated endocytosis mechanism. These results indicate that the multifunctional CLMNPs-tetrapeptide-FA copolymers possess a moderate CPT loading efficiency, low cytotoxicity, and favorable biocompatibility, and are promising candidates for tumor-targeted drug delivery.

Chitosan-based luminescent/magnetic hybrid nanogels for insulin delivery, cell imaging, and antidiabetic research of dietary supplements.

In this work, the chitosan-based luminescent/magnetic (CLM) nanomaterials were synthesized by direct gelation of chitosan, CdTe and superparamagnetic iron oxide into the hybrid nanogels. The morphology, sizes and properties of the nanogels prepared with different chitosan/QD/MNP ratios and under different processing parameters were researched. Fluorescence microscopy, FTIR spectra and TEM images confirmed the success of the preparation of the CLM hybrid nanogels. Spherical CLM hybrid nanogels with appropriate average sizes (<160 nm) were used for insulin loading. The actual loading amount of insulin was approximately 40.1mg/g. Human normal hepatocytes L02 cell line was used to explore the effects of additives, such as mangiferin (MF), (-)-epigallocatechin gallate (EGCG), and (-)-epicatechin gallate (ECG) on the insulin-receptor-mediated cellular uptake using insulin-loaded CLM (ICLM) hybrid nanogels. Above 80% of viability of L02 cells were watched at a nanogels concentration of 500 µg/mL whatever the additives existed or not. The study discovered that the fluorescent signals of the ICLM hybrid nanogels in L02 cells were more intense in the presence of MF, EGCG and ECG in medium than in the absence of these components, respectively. These results demonstrate that MF, EGCG and ECG are potentially able to enhance targeting combination of insulin with L02 cells and improve insulin sensitivity in L02 cells. The hybrid nanogels designed as a targeting carrier can potentially offer an approach for integration of insulin delivery, cell imaging, and antidiabetic investigation of dietary supplements.

The use of MRI apparent diffusion coefficient (ADC) in monitoring the development of brain infarction.

BACKGROUND: To study the rules that apparent diffusion coefficient (ADC) changes with time and space in cerebral infarction, and to provide the evidence in defining the infarction stages. METHODS: 117 work-ups in 98 patients with cerebral infarction (12 hyperacute, 43 acute, 29 subacute, 10 steady, and 23 chronic infarctions) were imaged with both conventional MRI and diffusion weighted imaging. The average ADC values, the relative ADC (rADC) values, and the ADC values or rADC values from the center to the periphery of the lesion were calculated. RESULTS: The average ADC values and the rADC values of hyperacute and acute infarction lesion depressed obviously. rADC values in hyperacute and acute stage was minimized, and increased progressively as time passed and appeared as "pseudonormal" values in approximately 8 to 14 days. Thereafter, rADC values became greater than normal in chronic stage. There was positive correlation between rADC values and time (P < 0.01). The ADC values and the rADC values in hyperacute and acute lesions had gradient signs that these lesions increased from the center to the periphery. The ADC values and the rADC values in subacute lesions had adverse gradient signs that these lesions decreased from the center to the periphery. CONCLUSION: The ADC values of infarction lesions have evolution rules with time and space. The evolution rules with time and those in space can be helpful to decide the clinical stage, and to provide the evidence in guiding the treatment or judging the prognosis in infarction.

[Imaging manifestation and clinical value in herniation pit of femoral neck].

OBJECTIVE: To discuss the imaging manifestation and clinical value in herniation pit of femoral neck. METHODS: One case proved by operation and pathology and twenty cases with typical imaging manifestation described by Pitt were reviewed retrospectively. There were 17 males and 4 females with an average age of 53 years old(ranging from 30 to 85 years). All cases were examined by X-ray films and CT, and 13 cases were performed with MRI. RESULTS: Twenty-nine lesions were found in the 21 cases, 9 cases were in right side, 8 cases were in left side, 4 cases were in both sides. The lesions were all located in the superior lateral part of the femoral neck and anterior lateral base of femoral head. The lesions were round or oval, and most of their greatest diameter was less than 16 mm. X-ray films showed a central radiolucency with a thin clear sclerotic rim or simple sclerotic loop. CT scans showed a well-defined lesion of soft-tissue attenuation with sclerotic margin. The lesions had focal cortical perforation. On MRI images,most lesions showed uniformly long T1 and long T2 fluid signal intensity. CONCLUSION: Herniation pit of femoral neck have some specific imaging features, CT can make accurate diagnosis. X-ray and MRI are helpful to diagnosis.

WITHDRAWN: Lipid peroxidation and antioxidant defense systems in tissues of a lizard (Phrynocephalus przewalskii) during hibernation.

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Effects of ambient temperature on lipid and fatty acid composition in the oviparous lizards, Phrynocephalus przewalskii.

This study was designed to assess the effect of ambient temperature on lipid content, lipid classes and fatty acid compositions of heart, liver, muscle and brain in oviparous lizards, Phrynocephalus przewalskii, caught in the desert area of China. Significant differences could be observed in the contents of the total lipid and fatty acid compositions among different temperatures (4, 25 and 38 degrees C). The study showed that liver and muscle were principal sites of lipid storage. Triacylglycerol (TAG) mainly deposited in the liver, while phospholipids (PL) was identified as the predominant lipid class in the muscle and brain. Palmitic and stearic acid generally occupied the higher proportion in saturated fatty acids (SFA), while monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) consisted mainly of 16:1n-7, 18:1n-9, 18:2n-6, 18:3n-3, 20:4n-6 and 22:6n-3 regardless of tissue and temperature. These predominant fatty acids proportion fluctuations caused by temperature affected directly the ratio of unsaturated to saturated fatty acids. There was a tendency to increase the degree of unsaturation in the fatty acids of TAG and PL as environmental temperature dropped from 38 to 4 degrees C, although the different extent in different tissues. These results suggested that lipid characteristics of P. przewalskii tissues examined were influenced by ambient temperature.

Synthesis of propenamides with anti-malarial activities and 3D-QSAR study.

AIM: To establish 3D QSAR model of propenamides with anti-malarial activities. METHODS: Chemical synthesis combined with comparative molecular field analysis (CoMFA). RESULTS: Generated QSAR models for activities of inhibiting chloroquine resistive malaria (W2) and chloroquine sensitive malaria (D6). CONCLUSION: The activity of anti-W2 depends mostly on steric interaction and the activity of anti-D6 depends on both steric and electrostatic interaction.

Endomorphins inhibit contractile responses of rat thoracic aorta rings induced by phenylephrine and angiotensin II in vitro.

AIM: To study the effects of opioid receptor agonists endomorphin-1 and -2 on contractile responses of rat thoracic aorta rings to phenylephrine (PE) and angiotensin II (Ang II), and their possible mechanism in vitro. METHODS: Isometric tension recording was progressed in thoracic aorta rings from Wistar rats. RESULTS: Pretreatment of morphine, endomorphin-1 and -2 (0.1, 1, and 10 micromol/L) could inhibit the contractile responses of the endothelium-intact aorta rings to PE (0.1 micromol/L) and Ang II ( 1 micromol/L) in a concentration-dependent manner (P < 0.01), but could not inhibit the contraction of rings without endothelium (P > 0.05). Naloxone (1 micromol/L) could partially antagonize the effects of endomorphine-1 and -2 (P < 0.01). N(omega)-nitro-L-arginine (L-NNA, 10 micromol/L) or endothelial rubbing could completely blocked the effects of morphine, endomorphine-1 and -2 (P < 0.01). CONCLUSION: Endomorphin-1 and -2 could inhibit PE- and Ang II-induced contractions of rat aorta rings, which was partially by naloxone-sensitive mechanism and related to the release of nitric oxide from vascular endothelium.