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The mesoporous gamma-alumina (γ-Al2O3) synthesized via evaporation-induced self-assembly method (EISA) using inorganic salt, Al(NO3)3·9H2O precursor and water-ethanol solvent mixture was implemented as a support for Co catalyst in methane dry reforming at 973–1073 K under 1 atm. The γ-Al2O3 support possessed filament-shaped morphology with surface area of 173.4 m2 g−1 and cobalt nanoparticles were successfully dispersed on support with small crystallite size of 7.8 nm. The stability of 10%Co/Al2O3 was evident for CH4 and CO2 conversions at 1023 and 1073 K. CH4 conversion could reach to 76.2% while 81.6% was observed for CO2 conversion at 1073 K. Although graphitic and amorphous carbons were unavoidably formed on used catalyst, 10%Co/Al2O3 exhibited an outstanding performance comparable to noble metals with the desired ratio of H2/CO for downstream Fischer-Tropsch process.

The impact of La2O3 promoter loading on alumina-supported cobalt catalysts was investigated in terms of physicochemical properties and catalytic performance for CO2 reforming of methane (CRM) at stoichiometric CH4/CO2 ratio and 1023 K. Both Co3O4 (with crystal size: 5.2–8.4 nm) and La2O3 nanoparticles were finely dispersed on support surface. The promotional La2O3 effect could noticeably increase CH4 and CO2 conversions to 29.3% and 17.3%, correspondingly due to improved basic site concentration and decreasing crystallite size of active metal in association with promoter addition. 5%La loading was an optimal promoter content for reactant conversions as well as yield of H2 and CO. 5%La-10%Co/Al2O3 also exhibited the highest resistance to carbon deposition owing to the basic nature, redox feature and oxygen vacancy of La2O3 dopant. Notably, the H2/CO ratio obtained within 0.84–0.98 is preferable for Fischer-Tropsch reaction in downstream to yield liquid hydrocarbon fuels.

This study aims to minimize electrode wear (EW) and maximize material removal rate (MRR) in powder mixed electrical discharge machining (PMEDM) process of 9CrSi alloy steel with silicon carbide powder. To achieve these objectives, Taguchi method and Grey Relational Analysis (GRA) are applied to optimize one two-level and four three-level PMEDM process parameters, including Ton, Toff, CP, IP and SV in eighteen experiments based on an orthogonal array L18 (21 and 43). Results have provided a set of optimal PMEDM process parameters in which Ton has the strongest effect on SW and MRR while that of CP is insignificant. The obtained minimum EW and maximum MRR have been verified and proven by a PMEDM experiment using optimal process parameters. The proposed method can be further applied to optimize other PMEDM process parameters for different objectives.

This paper presents a work on the effect of Powder Mixed Electric Discharge Machining (PMEDM) parameters on the machining time when machining cylindrical shaped parts made from 90CrSi alloy steel. Five parameters including pulse on time Ton, powder concentration Cp, pulse off time Toff, pulse current IP and server voltage SV are explored their contribution on machining time by using the Taguchi method in eighteen experiments based on an orthogonal array L18 (21 and 34). Based on ANOVA analysis, an optimum model of the machining time was proposed. The model was well verified by comparing with the experiment, and it, therefore can be used for further studies in the PMEDM process.

This work is done to determine the effects of the input factors of powder mixed electrical discharge machining (PMEDM) process on the material removal rate (MRR). In the study, the workpiece is cylindrical parts made from 90CrSi alloy steel. Also, five factors containing the pulse on time Ton, the powder concentration Cp, the pulse off time Toff, the pulse current IP, and the server voltage SV were discovered to find their impact on MRR. In addition, the Taguchi method and ANOVA analysis were used to design experiment and analyze the results. In addition, an optimal model of the MRR was introduced. Also, the model has been well verified by comparison with testing, and so it can be used for further studies in the PMEDM process.

The promotional La2O3 effect on the physicochemical features of mesoporous alumina (MA) supported cobalt catalyst and its catalytic performance for methane dry reforming (MDR) was examined at varied temperature and stoichiometry feedstock. The Co3O4 nanoparticles were evidently scattered on fibrous mesoporous alumina with small crystal size of 8–10 nm. The promotion behavior of La2O3 facilitated H2-reduction by providing higher electron density and enhanced oxygen vacancy in 10%Co/MA. The addition of La2O3 could reduce the apparent activation energy of CH4 consumption; hence, increasing CH4 conversion up to 93.7% at 1073 K. The enhancement of catalytic activity with La2O3 addition was also due to smaller crystallite size, alleviated H2-reduction and the basic character of La2O3. Lanthanum dioxycarbonate transitional phase formed in situ during MDR was accountable for mitigating deposited carbon via redox cycle for 17–30% relying on reaction temperature. Additionally, the oxygen vacancy degree increased to 73.3% with La2O3 promotion. The variation of H2/CO ratios within 0.63–0.99 was preferred for downstream generation of long-chain olefinic hydrocarbons.

Reduced graphene oxide-wrapped silver nanoparticles (Ag@rGO) were synthesized by a simple photochemical process with the GO nanosheets as both a stabilizing and reducing agent. The synthesized Ag@rGO nanohybrids were used as a localized surface plasmon resonance (LSPR) colorimetric sensor for the detection of chromium(VI) and carbaryl. For chromium(VI), the result showed a color change from yellow to colorless and linear-dependence of the absorption intensity on the concentration of Cr(VI) in the range 0.1–25 μM. For carbaryl, the calibration curve presented a high level of linearity in the range of 0.1–50 μM corresponding to color changes from yellow to purple. The limits of detection (LODs) for Cr(VI) and carbaryl were found to be 31 nM and 42 nM, respectively. The novel Ag@rGO nanohybrids will become an excellent platform for colorimetric probes in the detection of Cr(VI) ions and carbaryl or other heavy metal ions/pesticides.

BACKGROUND: Idiopathic epiretinal membrane (iERM) is an avascular proliferation of different types of cells between the posterior vitreous cortex and the internal limiting membrane. That causes visual impairment including blurry, distortion, scotoma. Many studies of iERM were done to describe the clinical characteristics and investigate the histopathology of this disease. Nonetheless, there has not been a study of iERM histopathology in Vietnam. AIMS: To describe clinical characteristics and histopathological results of idiopathic retinal membrane and the association between them. METHODS: A cross sectional decriptive study of 35 iERMs (33 patients) in Vietnam National Institute of Ophthalmology (VNIO). RESULTS: High morbidity incidence was in group age >50 years (32/35), female gender (26/35), limited movement works (27/35), and high educational levels (28/35). Distortion was the highest (77.14%), scotoma and floater was less frequent (28.5%, 45.7%). Macular edema in all cases and PVD and exudate were high frequent (65.7%, 62.8%). Symptom duration was 8.2 ± 4.7 months, (1-21 months). Mean of central macular thickness was 468.51 ± 97.24 µm (656-274 µm). Six types of cell were detected, including glial cell (35/35), fibroblast (23/35), myofibroblast (23/35), macrophage (13/35), lymphocyte (5/35) and neutrophil (2/35). The number of cell types in one sample ranged from 1-5 types (2.85 ± 1.28 cell types). Number of cell types were correlated to symptom duration (r = 0.47, p = 0.004, Pearson's test) and central macular thickness (r = 0.72, p < 0.001, Pearson's test). CONCLUSION: There were 6 types of cells in iERM. Glial cell was the most frequent cell, inflammatory cells (macrophage, lymphocyte, neutrophil) was also detected. The number of cell types was stastitically correlated to symptom duration and CMT.

Several novel of polymethoxyquercetin Mannich base derivatives (2-7) were synthesized through O-methylation and based on Mannich reaction with various secondary amines and formaldehyde, starting from abundant and inexpensive natural sources quercetin. All the synthesized compounds were confirmed by 1H NMR, 13C NMR and MS techniques and the synthetic compounds were test for antiproliferative activities on human cervical carcinoma Hela cell line by the standard CCK-8 assay, the result showed that most of the target compounds exhibited moderate to potent antiproliferative activities on Hela (cervical carcinoma) cell which is comparable to the positive control cis-Platin. Among them, polymethoxyquercetin Mannich base derivatives (2) showed the strongest activity (IC50 3.80 μM), they are potential and selective anticancer agent and worthy of further development

The unpromoted and B-promoted 10%Ni/SBA-15 catalysts synthesized via sequential incipient wetness impregnation approach were assessed for combined steam and CO2 reforming of methane (CSCRM) at various reaction temperatures of 973–1073 K and stoichiometric feed composition. An expected and noteworthy drop in mean NiO crystallite size and BET surface area with boron promotion from 1% to 5%B loading could be due to the agglomeration of B2O3 particles and deboration reaction during calcination and hence blocking mesopores of SBA-15 support at elevated B composition. The complete NiO reduction to metallic Ni0 form was achieved during H2 activation and the reduction temperature of NiO phase was shifted towards higher temperature with B-addition owing to enhancing interaction between the acidic B2O3 and basic NiO phases. For all reaction temperature employed, 3%B appeared to be the optimal promoter loading in terms of reactant conversions and 3%B-10%Ni/SBA-15 catalyst revealed the greatest H2 yield (69.4%) at 1073 K. In addition, CH4 and CO2 conversions were enhanced about 23.2% and 32.4%, correspondingly with rising reaction temperature from 973 to 1073 K. Ratio of H2 to CO varied from 1.26 to 2.71 and the desired H2/CO ratio of about 2 favored for Fischer-Tropsch synthesis was achieved on 3%B-10%Ni/SBA-15 sample at 973 K. Boron promoter suppressed graphitic carbon formation and the amount of carbonaceous deposition was reduced about 4 times. Noticeably, 3%B-10%Ni/SBA-15 was also resilient to metallic Ni0 re-oxidation throughout CSCRM.

A series of novel 1,3-thiazole derivatives (5a-i) with a modified phenothiazine moiety were synthesized and tested against cancer cell line MCF-7 for their cytotoxicity. Most of them (5a-i) were less cytotoxic or had no activity against MCF-7 cancer cell line. Material and Methods: The IC50 value of compound (4) was 33.84 μM. The compounds (5a-i) were also evaluated for antimicrobial activities, but no significant activity was observed. The antioxidant activity was conducted for target compounds (5a-i). The IC50 value of compound (5b) was 0.151mM. Results: The total amount of energy, ACE (atomic contact energy), energy of receptor (PDB: 5G5J), and ligand interaction of structure (4) were found to be 22.448 Kcal.mol-1 , -247.68, and -91.91 Kcal.mol-1, respectively. The structure (4) is well binded with the receptor because the values of binding energy, steric energy, and the number of hydrogen bondings are -91.91, 22.448 kcal.mol-1, and 2, respectively. It shows that structure (4) has good cytotoxicity with MCF-7 in vitro. Conclusion: The increasing of docking ability of structures (5a-i) with the receptor is presented in increasing order as (5f)>(5e)>(5g)>(5a)>(5b)>(5d)>(5c)>(5i)>(5h). The structure bearing substitution as thiosemicarbazone (4), nitrogen heterocyclic (5f), halogen (5e), and azide (5g) showed good cytotoxicity activity in vitro.

In this work, a multi-functional hybrid system consisting of graphene oxide and silver nanoparticles (GO-Ag NPs) was successfully synthesized by using a two-step chemical process. We firstly demonstrated noticeable bactericidal ability of the GO-Ag hybrid system. We provide more chemo-physical evidence explaining the antibacterial behavior of GO-Ag nanohybrid against Gram-negative Escherichia Coli and Gram-positive Staphylococcus aureus in light of ultrastructural damage analyses and Ag1+ ions release rate onto the cells/medium. A further understanding of the mode of antimicrobial action is very important for designing and developing advanced antimicrobial systems. Secondly, we have also demonstrated that the GO-Ag nanohybrid material could be used as a potential surface enhanced Raman scattering (SERS) substrate to detect and quantify organic dyes, e.g., methylene blue (MB), in aqueous media. Our findings revealed that the GO-Ag hybrid system showed better SERS performance of MB detection than that of pure Ag-NPs. MB could be detected at a concentration as low as 1 ppm. The GO-Ag-based SERS platform can be effectively used to detect trace concentrations of various types of organic dyes in aqueous media. With the aforementioned properties, the GO-Ag hybrid system is found to be very promising as a multi-functional material for advanced biomedicine and environmental monitoring applications.

This study reports on the cellular uptake of folate tethered micelles using a branched skeleton of poly(ethylene glycol) and poly(e-caprolactone). The chemical structures of the copolymers were characterized by proton nuclear magnetic resonance spectroscopy, and Fourier transform infrared spectroscopy. Doxorubicin (DOX) was utilized as an anticancer drug. The highest drug loading efficiencies of DOX in the folate decorated micelle (DMCF) and folate-free micelle (DMC) were found to be 88.5% and 88.2%, respectively, depending on the segment length of the poly(e-caprolactone) in the copolymers. A comparison of fluorescent microscopic images of the endocytosis pathway in two cell lines, human breast cancer cells (MCF-7) and human oral cavity carcinoma cells (KB), revealed that the micelles were engulfed by KB and MCF-7 cells following in vitro incubation for one hour. Flow cytometric analysis revealed that free folic acid can inhibit the uptake of DOX by 48%–57% and 26%–39% in KB cells and MCF-7 cells, respectively. These results prove that KB cells are relatively sensitive to folate-tethered micelles. Upon administering methyl-β-cyclodextrin, an inhibitor of the caveolae-mediated endocytosis pathway, the uptake of DOX by KB cells was reduced by 69% and that by MCF-7 cells was reduced by 56%. This finding suggests that DMCF enters cells via multiple pathways, thus implying that the folate receptor is not the only target of tumor therapeutics.

Direct competitive enzyme-linked immunosorbent assay (ELISA) for 2,4-dichlorophenoxyacetic acid (2,4-D) was developed. Varying the concentrations of monoclonal anti-2,4-D-antibody and the conjugate of soybean peroxidase and 2,4-D the conditions of ELISA performance were optimised. The chemiluminescent method based on peroxidase-catalysed oxidation of luminol was applied to measure the enzyme activity of the conjugate. A mixture of 3-(10′-phenothiazinyl)propane-1-sulfonate and 4-morpholinopyridine was used as potent enhancer of chemiluminescence signal. It was shown that the values of the lower detection limit, IC 50 and the working range were 1.5, 64.0, and 6.5–545 ng/mL, respectively. The recovery values of CL-ELISA from 10 spiked samples of oranges ( n = 5) and mandarins ( n = 5) cultivated in green house without use of 2,4-D and containing different 2,4-D concentrations (10–300 ng/mL) were ranged from 92% to 104% that indicated on the absence of matrix effect for the fruit extracts of interest. Determination of 2,4-D in peel of five oranges and five mandarins purchased from stores in Vietnam showed that 2,4-D content in oranges fruits (79–104 μg/kg) was significantly higher than that in mandarins (1.66–2.82 μg/kg).

Star-shaped co-polymers based on the backbone of poly(ε-caprolactone) were synthesized by a ring-opening reaction using pentaerythritol as initiator and Sn(Oct)(2) as catalyst. The star-shaped poly(ε-caprolactone) polymer was then chain extended with a terminal block of poly(ethyl ethylene phosphate) to form a copolymer, poly(ε-caprolactone)-poly(ethyl ethylene phosphate), when using the cyclic ethyl ethylene phosphate monomer. The amphiphilic block co-polymers can self-assemble into nanoscopic micelles with a mean diameter of 150 nm and a spherical shape. Additionally, the prepared micelles did not induce hemolysis and nitric oxide production in vitro based on nitric oxide, hemolytic tests and MTT assays. The hydrophobic micellar cores encapsulated doxorubicin (DOX) in an aqueous solution with a loading efficiency of 55.2%. The in vitro release of DOX from DOX-loaded micelles was pH dependent. DOX-loaded micelles present significantly enhanced cytotoxicity to both MCF-7/drug-sensitive and MCF-7/drug-resistant cells after second incubation. Moreover, results of confocal microscopy and flow cytometry of DOX-loaded micelles demonstrate the feasibility of this delivery system for effective therapy of drug-resistant tumours.

The triblock copolymer is composed of two identical hydrophilic segments: Monomethoxy poly(ethylene glycol) (mPEG) and one hydrophobic segment poly(e‑caprolactone) (PCL); which is synthesized by coupling of mPEG-PCL-OH and mPEG‑COOH in a mild condition using dicyclohexylcarbodiimide and 4-dimethylamino pyridine. The amphiphilic block copolymer can self-assemble into nanoscopic micelles to accommodate doxorubixin (DOX) in the hydrophobic core. The physicochemical properties and in vitro tests, including cytotoxicity of the micelles, have been characterized in our previous study. In this study, DOX was encapsulated into micelles with a drug loading content of 8.5%. Confocal microscopy indicated that DOX was internalized into the cytoplasm via endocystosis. A dose-finding scheme of the polymeric micelle (placebo) showed a safe dose of PEG-PCL-PEG micelles was 71.4 mg/kg in mice. Importantly, the circulation time of DOX-loaded micelles in the plasma significantly increased compared to that of free DOX in rats. A biodistribution study displayed that plasma extravasation of DOX in liver and spleen occurred in the first four hours. Lastly, the tumor growth of human breast cancer cells in nude mice was suppressed by multiple injections (5 mg/kg, three times daily on day 0, 7 and 14) of DOX-loaded micelles as compared to multiple administrations of free DOX.

New complexes of 5,11,17,23-tetra[(2-ethyl acetoethoxyphenyl)(azo)phenyl]calix[4]arene (TEAC) with Pb(II) and Cr(III) were prepared in basic solution with a mixture of MeOH and H2O as solvent. The ratio of TEAC and metal ion in complexes was found to be 1 : 1 under investigated condition. The complex formation constants (based on Benesi-Hildebrand method) for TEAC-Pb(II) and TEAC-Cr(III) were 4.03 × 104and 1.2 × 104, respectively. Additionally, the molar extinction coefficients were 5 × 104and 1.42 × 104for TEAC-Pb(II) and TEAC-Cr(III), respectively. The H-Point Standard Addition Method (HPSAM) has been applied for simultaneous determination of complexes formation of Cr(III)/Pb(II) and TEAC with concentration from 2 : 1 to 1 : 20 (w/w). The proposed method was successfully utilized to invest lead and chromium contents in plating wastewater samples. The results for several analyzed samples were found to be in satisfied agreement with those acquired by using the inductively coupled plasma mass spectrometry (ICP-MS) technique.

The amphiphilic block copolymer methoxy-poly(ethylene glycol)-poly(epsilon-caprolactone) (mPEG-PCL) was grafted to 2-hydroxyethyl cellulose (HEC) to produce nano-sized micellar nanoparticles. The nanoparticles were loaded with anti-tumor drug, doxorubicin (DOX) and the size of the DOX-loaded nanoparticles were determined by dynamic light scattering (DLS) in aqueous solution to be from 197.4 to 230 nm. The nanoparticles subjected to co-culture with macrophage cells showed that these nanoparticles used as drug carrier are not recognized as foreign bodies. Overexpression of P-glycoprotein (P-gp) is an important factor in the development of multidrug resistance (MDR) in many cancer cells. In this study, Western blot and Rhodamine 123 were used to monitor the relative P-glycoprotein expression in human breast cancer cell lines MCF-7/WT and MCF-7/ADR. The endocytosis of the DOX-loaded nanoparticles by breast cancer cells is more efficient observed under a confocal laser scanning microscopy (CLSM) and a flow cytometry in MCF7/ADR cells, compared to the diffusion of the free drug into the cytoplasm of cells. Based on these findings, we concluded that the nanoparticles made from mPEG-PCL-g-cellulose were effective in overcoming P-gp efflux in MDR breast cancer cells.

The drug delivery systems using conventional nanocarriers are associated with the systemic toxicity and poor bioavailability of drug due to lack of its specificity. The objective of this study is to overcome these limitations by introduction of folic targeting ligand in drug delivery system to deliver drug within tumor cells via passive and active-mediated endocytosis. Hence, the folate decorated-micelles based on the star-shape FOL-PEG-PCL copolymer were prepared for targeting to the folate receptor overexpressing in human breast cancer cells. The structure was characterized by 1H NMR, FT-IR and DSC. The self assembly of amphiphilic copolymer was investigated. The particle size of the micelle was 110.5 nm. The safety evaluation of copolymeric micelle including the in vitro nitric oxide production and hemolytic tests. The results obtained from macrophage response and hemolysis test suggest that the micelle prepared in this study had moderate in vitro toxicity and could be safely used for intravenous injection in animal.

Triblock copolymers of monomethoxy poly(ethylene glycol) (mPEG) and e-caprolactone (CL) were prepared with varying lengths of poly(e-caprolactone) (PCL) compositions and a fixed length of mPEG segment. The molecular characteristics of triblock copolymers were characterized by 1H NMR, gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). These amphiphilic linear copolymers based on PCL hydrophobic chain and hydrophilic mPEG ending, which can self-assemble into nanoscopic micelles with their hydrophobic cores, encapsulated doxorubicin (DOX) in an aqueous solution. The particle size of prepared micelles was around 40–92 nm. The DOX loading content and DOX loading efficiency were from 3.7–7.4% to 26–49%, respectively. DOX-released profile was pH-dependent and faster at pH 5.4 than pH 7.4. Additionally, the cytotoxicity of DOX-loaded micelles was found to be similar with free DOX in drug-resistant cells (MCF-7/adr). The great amounts of DOX and fast uptake accumulated into the MCF-7/adr cells from DOX-loaded micelles suggest a potential application in cancer chemotherapy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Cancer chemotherapy is believed to be impeded by multidrug resistance (MDR) and nonspecific accumulation. This study used methoxy poly-(ethylene glycol) (mPEG, A block) and poly-(e-caprolactone) (PCL, B block) to synthesize an AB2 type amphiphilic block copolymer to encapsulate the anticancer drug, Doxorubicin (DOX). The molecular weight of copolymer was measured as 19 kDa by a gel permeation chromatography and 15 kDa by proton nuclear magnetic resonance. The amphiphilic block copolymer self-assembled into micelles and critical micelle concentration was 43.7×10− 3 mg/mL. The particle size of empty micelle was 95.1 nm, while it decreased to 21.4 nm after loading with DOX, corresponding to a drug loading efficiency of 22.29%. In the in vitro release experiment, 50% DOX released from the micelles at pH 5 and 40 % at pH 7.4 in 48 hours. The nitric oxide assay indicated that the micelles could avoid recognition by macrophage. Rhodamine 123 assay using flow cytometer showed that the fluorescence of intracellular DOX was stronger in MCF-7/WT than that of MCF-7/ADR. The half lethal dose (IC50) of DOX-loaded micelles for MCF-7/WT and MCF-7/ADR were 0.285 μg/mL and 7.476 μg/mL, respectively. These values are about 7.9-fold higher than the IC50 of free DOX for MCF-7/WT and MCF-7/ADR at 0.036 μg/mL and 0.937 μg/mL, respectively. This can be due to a slow release rate of DOX from micelles. Confocal images showed that DOX-loaded micelles accumulated mostly in the cytoplasm instead of nuclei. On the contrary, free DOX diffused throughout the cells. Flow cytometry histograms indicated that the number of MCF-7/ADR cells under the same fluorescence intensity was about 83.16% and 50.91% for DOX- loaded micelles and free DOX, respectively. In conclusion, the DOX-loaded micelles formed by AB2 copolymer was able to overcome multidrug resistance of breast cancer cells as it can accumulate more in MCF-7/ADR cells compare to free DOX.

Triblock copolymers of monomethoxy poly (ethylene glycol) (mPEG, Mw= 5000) and poly(ɛ-caprolactone) (PCL) were prepared with different length of PCL compositions. Initially diblock copolymer of mPEG-PCL was synthesized by ring opening polymerization of mPEG with ɛ-caprolactone with SnOct as catalyst. The diblock copolymer was reacted with carboxylic acid terminated mPEG via coupling reaction. The amphiphilic block copolymers were based on hydrophobic (PCL) segments and two hydrophilic (PEG) segments. The structures of ring opening polymerization and triblock copolymer were characterized by 1H NMR and FT-IR spectroscopy. These copolymers can self-assembly into nanoscopic micelles. The size and size population distribution of micelles were also determined by dynamic light scattering (DLS). The nanoparticle sizes are around 16–30 nm. The cytotoxicity of copolymeric nanoparticles was investigated against mouse fibroblast cells lines (L929).

Y-shaped amphiphilic copolymers have been synthesized by various strategies. They can self-assemble to form stable micellar drug carriers. Higher ratio of hydrophobic segment in these micelles is known to stabilize encapsulated drugs. This study used methoxy poly(ethylene glycol) (mPEG, A block) and poly(ε-caprolactone) (PCL, B block) to synthesize an AB2 type amphiphilic block copolymer to encapsulate the anticancer drug, doxorubicin (DOX). The synthesized mPEG-(PCL)2 self-assembled into nanoparticles and its critical micelle concentration was 43.7 × 10-3 mg/mL. The particle size of empty micelle and DOX-loaded micelle was 95.1 and 21.4 nm, respectively. DOX-loaded micelles have a drug- loading efficiency of 22.3% and could be released from micelles up to 50% at pH 5 and 40% at pH 7.4 in 48 h in an in vitro release experiment. The nitric oxide (NO) assay indicated that the micelles could avoid the cytotoxic recognition by murine macrophage cells. The half-lethal dose (IC50) of DOX-loaded micelles for two human breast cancer cell lines (MCF-7/WT for wild-type and MCF-7/ADR for adriamycin-resistant) were 0.937 and 7.476 μg/mL, respectively. For MCF-7/ADR cells, the ratio of IC50 of free DOX vs. that of DOX-loaded micelles, which reported as resistance reversion index, was 0.125. Confocal images showed that DOX-loaded micelles accumulated mostly in the cytoplasm instead of nuclei. On the contrary, free DOX diffused throughout the cells. Flow cytometric histograms indicated that the fluorescence intensity in MCF-7/ADR cell line was about 83.2% and 50.9% for DOX-loaded micelles and free DOX, respectively. This result indicates that the DOX-loaded micelles formed by AB2 copolymer could overcome multidrug resistance of breast cancer cells as it can accumulate more in MCF-7/ADR cells compared with free DOX.

Antimicrobials are extensively used as growth promoters in animal feeds worldwide, but reliable estimates are lacking. We conducted an internet-based survey of commercial chicken and pig feed products officially approved for sale in Vietnam over the period March-June 2015. Information on the antimicrobial contents in feed products, alongside animal production data, was used to estimate in-feed antimicrobial consumption to produce one kilogram of live animal (chicken, pig), as well as to estimate country-wide antimicrobial consumption through animal feeds. A total of 1462 commercial feed formulations were examined. The survey-adjusted estimated antimicrobial contents were 25.7 and 62.3 mg/kg in chicken and pig feeds, respectively. Overall, it was estimated that 77.4 mg [95% CI 48.1-106.8] and 286.6 mg [95% CI 191.6-418.3] of in-feed antimicrobials were used to raise 1 kg of live chicken and pig, respectively. Bacitracin (15.5% feeds), chlortetracycline (11.4%), and enramycin (10.8%) were the most common antimicrobials present in chicken feed formulations, whereas bacitracin (24.8%), chlortetracycline (23.9%), and florfenicol (17.4%) were the most common in pig feed formulations. Overall, 57% of the total quantitative usage consisted of antimicrobials regarded by WHO of importance for human medicine, including amoxicillin, colistin, tetracyclines, neomycin, lincomycin, and bacitracin. These figures confirm a very high magnitude of in-feed consumption of antimicrobials, especially in pig production. Results from this study should encourage further monitoring of antimicrobials used in animal production, and foster discussion about existing policies on inclusion of antimicrobials in animal feed rations.