Kılıçay, Ebru | Karahaliloğlu, Zeynep | Alpaslan, Pınar | Hazer, Baki | Denkbaş, Emir Baki

Article | 2017 | JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION28 ( 15 ) , pp.1762 - 1785

Antisense oligonucleotide (ASO)-conjugated--tocopherol succinate (TCS)-loaded-poly(lactic acid)-g-poly(ethylene glycol) nanoparticles (ASO-TCS-PLA-PEG NPs), with the ratio of polymer/TCS of 10:2.5, 10:5, 10:7 (w/w) were prepared for targeting cancer therapy. The amphiphilic PLA, amino terminated PEG graft copolymers were synthesized by ring opening polymerization reaction. Nanoparticles were produced by using double emulsion (w/o/w) solvent evaporation method. ASO-TCS-PLA-PEG NPs demonstrated satisfactory encapsulation and loading efficiency and size distribution. The short-term stability studies were carried out at 4 and 25 degrees . . . C for 30days to assess their mean particle size, polydispersity index and zeta potential. The cellular uptake and extended cytoplasmic retention of the NPs in A549 human lung carcinoma and L929 mouse fibroblast cells were examined by fluorescence and confocal microscopy. In human lung cancer cells, ASO-TCS-PLA-PEG NPs exhibited better cellular internalization, cytotoxicity and apoptotic and necrotic effects compared to healthy cell line, L929. These findings showed that ASO-modified nanoparticles could serve as a promising nanocarrier for targeted tumor cells Daha fazlası Daha az

Nalbant, Muammer | Altın, Abdullah | Gökkaya, Hasan

Article | 2007 | Materials and Design28 ( 4 ) , pp.1334 - 1338

The effects of cutting speed and cutting tool geometry on cutting forces are investigated in this study. For this purpose, nickel-base super alloy, Inconel 718, is machined with dry cutting conditions by using digital controlled computer lathe with ceramic cutting tools in two different geometries and three different material qualities. Metal removing process is carried out for four different cutting speeds (150 m/min, 200 m/min, 250 m/min, and 300 m/min), while a cutting depth of 2 mm and a feed rate of 0.20 mm/rev are kept constant. As a result of the experiments, the lowest main cutting force, which depends on tool geometry, is o . . .btained as 672 N with KYON 2100 SNGN 120712 ceramic tool and the maximum cutting force is determined as 1346 N with the ceramic cutting tool having KYON 4300 RNGN 120700 geometry. Depending on the cutting speed, the lowest main cutting force is recorded as 812 N at 250 m/min while the highest main cutting force is recorded as 955 N at 150 m/min. Plastic deformation, flank edge wear, notch and build-up edge are determined in high cutting speeds. © 2006 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Nalbant, Muammer | Altın, Abdullah | Gökkaya, Hasan

Article | 2007 | Materials and Design28 ( 5 ) , pp.1719 - 1724

In this study, the effects of cutting tool coating material and cutting speed on cutting forces and surface roughness are investigated. For this purpose, nickel based super alloy Inconel 718 is machined at dry cutting conditions with three different cemented carbide tools in CNC lathe. Metal removing process is carried out for five different cutting speeds (15, 30, 45, 60, 75 m/min.) while 2 mm depth of cut and 0.20 mm/rev feed rate are to be constant. Main cutting force, Fc is considered to be cutting force as a criterion. In the experiments, depending on the tool coating material, lowest main cutting force is found to be 506 N at . . .75 m/min with multicoated cemented carbide insert whose top layer is coated by Al2O3. Lowest average surface roughness (0.806 µm) is obtained at the cutting speed of 15 m/min with single coated (TiN) cemented carbide inserts. © 2006 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Karahaliloğlu, Zeynep | Kılıçay, Ebru | Alpaslan, Pınar | Hazer, Baki | Denkbaş, Emir Baki

Article | 2018 | JOURNAL OF BIOACTIVE AND COMPATIBLE POLYMERS33 ( 1 ) , pp.38 - 62

The development of novel combination anticancer drug delivery systems is an important step to improve the effectiveness of anticancer treatment in metastatic breast cancer and to overcome increased toxicity of the currently used combination treatments. The aim of this study was to assess efficient targeting, therapeutic efficacy, and bioavailability of a combination of drugs (curcumin and -tocopheryl succinate) loaded polystyrene-polysoyaoil-diethanol amine nanoparticles. Polystyrene-polysoyaoil-diethanol amine nanoparticles encapsulating two drugs, individually or in combination, were prepared by double-emulsion solvent evaporation . . . method, resulting in particle size smaller than 250nm with a surface negative charge between -30 and -40mV. Entrapment efficiency of curcumin and -tocopheryl succinate in the epigallocatechin gallate-conjugated dual-drug-loaded nanoparticles was found to be 68% and 80%, respectively. The release kinetics of curcumin and -tocopheryl succinate from the nanoparticles exhibited a gradual and continuous profile followed by an initial burst behavior with a release over 20days in vitro. Next, we have investigated the anticancer activity of nanoparticles encapsulating both the drugs and individually drug in human breast cancer cells (MDA-MB-231) using double-staining-based cell death analysis, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assessment of cytotoxicity and flow cytometer. In vitro cytotoxicity studies revealed that epigallocatechin gallate--tocopheryl succinate/curcumin-polystyrene-polysoyaoil-diethanol amine nanoparticles are more potent than the corresponding -tocopheryl succinate/curcumin-polystyrene-polysoyaoil-diethanol amine nanoparticles and their single-drug-loaded forms and show a synergistic and breast tumor targeting function. Thus, here, we propose epigallocatechin gallate-conjugated curcumin and -tocopheryl succinate-loaded polystyrene-polysoyaoil-diethanol amine nanoparticles which effectively inhibit tumor growth and reduce toxicity compared to single-drug chemotherapy Daha fazlası Daha az