Increasing the biocompatibility of graphene-based hybrid nanostructures with glycopolymer.

Hybrid nanostructures decorated with glycopolymers are appropriate for biomedical applications. In this paper, the results are obtained from nanographene (NG) decorated with glycoblock copolymer to increase their potential in use in therapies and in examining lectin interactions. A pyren-1-ylmethyl 4-cyano-4-((phenylcarbonothioyl)thio)pentanoate (CPADB-py) chain transfer agent was used in the synthesis of methyl methacrylate glycoblock copolymers (P2 and P3) by reversible addition-fragmentation chain transfer (RAFT) polymerization to adhere the polymer to the nanographene surface. Hybrid nanographenes (NG-1 and NG-2) were obtained by the non-covalent interaction of deprotected P2 and P3 with different fructopyranose groups (3-O-methacryloyl-1,2:4,5-di-O-isopropylidene-ß-D-fructopyranose and 1-O-methacryloyl-2,3:4,5-di-O-isopropylidene-ß-D-fructopyranose) in their backbones. Images obtained from transmission electron microscopy (TEM) of NG-1 and NG-2 show that glycoblock copolymer coating was performed homogeneously. Moreover, thermal gravimetric analysis (TGA) also confirmed a glycoblock copolymer coating of NG-1 and NG-2 by weight loss of 41% and 31%, respectively. In the last step of the study, the binding ability of glycoblock copolymers (P2-hyd and P3-hyd) with concanavalin A (ConA) lectin was investigated by a turbidimetric assay. Promising results were obtained from P3-hyd for the ConA interactions. Hence, this study may open a new avenue in the design of new multifunctional glyconanomaterials that show favorable binding properties with lectins.

Glycopolymer decorated multiwalled carbon nanotubes for dual targeted breast cancer therapy.

Carbon-based nanomaterials (CNMs) have attracted great attention in biomedical applications such as cancer imaging and therapy. CNMs, which are currently used in a wide range of applications, suffer from drawbacks of toxicity and low biocompatibility. Either noncovalent or covalent functionalization of CNMs with hydrophilic and biocompatible polymers which help to block hydrophobic interactivity between CNMs and cells can greatly increase their biocompatibility by eliminating their probable toxicity towards living organisms. In this report, we present a comparison of both noncovalent and covalent functionalization approaches in order to introduce a biocompatible glycoblock copolymer onto multi-walled carbon nanotubes (CNTs) in order to enhance their potential in therapies. An anticancer drug (doxorubicin, Dox) was conjugated with two different end functionalized poly(1-O-methacryloyl-ß-d-fructopyranose-b-(2-methacryloxyethoxy))benzaldehyde glycoblock copolymers, which were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization, by either noncovalent or covalent tethering. CNTs were coated separately with the synthesized drug-conjugated glycoblock copolymers and folic acid (FA) to obtain an efficient drug delivery platform for dual-targeting of glucose transporter protein (GLUT5) and folic acid receptors (FR) in breast cancer. A library of synthesized monomers, polymers and prepared glycoblock copolymer coated CNTs (hybrid-CNTs) using both approaches were comprehensively characterized by various techniques. Transmission electron microscopy measurements showed the homogeneous, smooth morphology of the prepared Dox-conjugated glycoblock copolymer coating of CNTs and confocal laser scanning microscopy images displayed successful cellular internalization of hybrid-CNTs in the MCF-7 and MDA-MB-231 human breast cancer cell lines. This research demonstrates the potential of hybrid-CNTs as a biocompatible drug delivery system as well as in vitro use of Dox-conjugated vehicles for dual receptor mediated breast cancer therapy.

Polymerization characteristics of colored compomers cured with different LED units.

AIM:: Incomplete polymerization of a resin material used for dental restoration affects the properties of the restoration. We evaluated the structural and mechanical properties of three different colored compomers cured with three different LED units to observe the characteristic changes occurring in different matches. METHODS:: Polytetrafluoroethylene molds (5 mm in diameter and 2 mm in thickness) were used to prepare disk-shaped sample specimens. Nine sample groups (each of five specimens) were prepared, three each of different compomer resin colors (gold, berry, and silver). Samples were cured using three different LED units (Optima, VALO, and Demi Ultra), according to the manufacturers' instructions. Microstructural properties of samples were characterized by determining the degree of curing using Fourier-transform infrared spectroscopy and by analyzing sample morphology under a scanning electron microscope. The Vickers hardness, compressive strength, and elastic modulus of the samples were measured to investigate their mechanical properties. RESULTS:: The degrees of curing decreased in the order of silver > berry > gold for all curing units. Conversely, gold compomers exhibited poorer mechanical values than the berry and silver counterparts. The Optima 10 unit yielded slightly higher degrees of curing than the other devices, followed by Demi Ultra and VALO light-curing units, respectively. CONCLUSION:: The resin color affected the structural and mechanical properties of the compomers, possibly as a result of the complex interactions and relationships between the irradiation light and resin material, such as light absorbance and reflectance; thus, depending on the color as well as the curing protocol.

Structural and mechanical properties of a giomer-based bulk fill restorative in different curing conditions.

The main goal of this study was to compare the polymerization degree of bulk-fill giomer resin cured with three different light-curing units (LCUs): a polywave third-generation (Valo); a monowave (DemiUltra: DU); and a second-generation LED (Optima 10: Opt) LCUs by using structural and mechanical properties. Giomer samples of 2 and 4 mm cured with three LCUs were employed in vitro analysis. The degree of curing (DC%) was determined with Fourier-Transform Infrared Spectroscopy (FTIR). Microstructural features were observed with scanning electron microscopy (SEM). Flexural strength (FS), compression strength (CS), elastic modulus and fracturing strain were determined for mechanical properties. Surface microhardness (SMH) values were also measured. Oneway ANOVA, two-way analysis of variance and Tukey multiple comparison tests were used for statistically analyzing the FS and SMH. DC% values were 58.2, 47.6, and 39.7 for the 2 mm samples cured with DU, Opt., and Valo LCUs, respectively. DC% values of the 4 mm samples were 50.4, 44.6, and 38.2 for DU, Opt, and Valo, respectively. SMH values were Valo, Opt

Structural and mechanical properties of a giomer-based bulk fill restorative in different curing conditions

ABSTRACT Objective: The main goal of this study was to compare the polymerization degree of bulk-fill giomer resin cured with three different light-curing units (LCUs): a polywave third-generation (Valo); a monowave (DemiUltra: DU); and a second-generation LED (Optima 10: Opt) LCUs by using structural and mechanical properties. Material and methods: Giomer samples of 2 and 4 mm cured with three LCUs were employed in vitro analysis. The degree of curing (DC%) was determined with Fourier-Transform Infrared Spectroscopy (FTIR). Microstructural features were observed with scanning electron microscopy (SEM). Flexural strength (FS), compression strength (CS), elastic modulus and fracturing strain were determined for mechanical properties. Surface microhardness (SMH) values were also measured. Oneway ANOVA, two-way analysis of variance and Tukey multiple comparison tests were used for statistically analyzing the FS and SMH. Results: DC% values were 58.2, 47.6, and 39.7 for the 2 mm samples cured with DU, Opt., and Valo LCUs, respectively. DC% values of the 4 mm samples were 50.4, 44.6, and 38.2 for DU, Opt, and Valo, respectively. SMH values were Valo, Opt<DU at top of the samples; Valo<DU, Opt at 2 mm, and DU, Valo<Opt at 4 mm depth. Giomer samples cured with Opt and DU exhibited higher FS values than Valo. CS values were similar but compressive modulus and fracturing strain (%) varied depending on the curing protocol. Conclusions: Based on the results, it can be concluded that curing device and protocol strongly affect crosslinking reactions and thus DC%, SMH, compressive modulus and strain at break values. Consequently, it can be deduced that curing protocol is possibly the most important parameter for microstructure formation of highly-filled composite restoratives because it may bring some structural defects and physical frailties on restorations due to lower degree of polymerization.

Chitosan and carboxymethyl cellulose based magnetic nanocomposites for application of peroxidase purification.

Recently, protein purification methods have a very wide area of research. Many of these methods are both expensive and multi-stage methods, that are needed in specific equipment. In this study, biopolymer coated magnetic nanoparticles, carboxymethyl cellulose (CMC) and chitosan (CH) coated Fe3O4 (magnetite) nanocomposites, are used in a new purification process. The structure of the synthesized magnetic nanocomposites were characterized by Fourier transform infrared (FTIR) spectrometry, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), thermogravimetric (TGA) analysis and zeta potential for surface charge of magnetic nanocomposites. Molecular weight and purification degree of peroxidase were estimated with SDS-PAGE. Peroxidase enzyme was purified a yield of 82.55% with carboxymethyl cellulose and 76.72% with chitosan using this method.

Preparation and in vitro evaluation of 5-flourouracil loaded magnetite-zeolite nanocomposite (5-FU-MZNC) for cancer drug delivery applications.

In this work, super paramagnetic magnetite nanoparticles were synthesized onto/into zeolite, then loaded with anti-cancer drug 5-fluorouracil (5-FU). The physical properties of the prepared nanocomposite and drug loaded nanocomposite were characterized using different techniques. The drug loading and releasing behavior of the magnetic nanocarrier was investigated and the drug-loaded nanoparticles exhibited a sustained release of drug without any burst release phenomenon. Furthermore, 5-FU loaded MZNC were evaluated for its biological characteristics. The functional 5-FU-MZNC has been triggered intra-cellular release of the cancer therapeutic agent 5-fluorouracil (5-FU). Cytotoxic effects of 5-FU loaded MZNC on human gastric carcinoma (AGS) cells were determined by real time cell analysis and colorimetric WST-1 cell viability assay. Apoptosis of cells was further investigated by Annexin-V staining which indicates the loss of cell membrane integrity. According to our results, 5-FU-MZNC showed a concentration-dependent cell proliferation inhibitory function against AGS cells. Morphologic and apoptotic images were consistent with the cytotoxicity results. In conclusion, 5-FU loaded MZNC efficiently inhibit the proliferation of AGS cells in vitro through apoptotic mechanisms, and may be a beneficial agent against cancer, however further animal study is still required.

Electrochemical sensing platforms based on the different carbon derivative incorporated interface.

their effects on the properties of these biosensors. Biosensors were prepared by Horseradish peroxidase (HRP) immobilization on the composite electrodes composed of carbon black, carbon nanofiber (CNF), extended graphite, multiwalled carbon nanotube (MWCNT), reduced graphene oxide (REGO) and poly(glycidyl methacrylateco-vinylferrocene) (P(GMA-co-VFc)) as mediator, covalent linker, and host matrix for carbon derivatives. The modified pencil graphite electrode (PGE) was used for the detection of hydrogen peroxide and to follow electrochemical behavior of different carbon derivatives which were recorded. The electrochemical characterization was investigated by cyclic voltammetry and electrochemical impedance spectroscopy methods. Amperometric measurements showed that the REGO and MWCNT modified electrodes have excellent performance in comparison with other carbon derivatives studied.

Spectrofluorimetric assay of ciprofloxacin hydrochloride in tablets.

OBJECTIVE: To describe the spectrofluorimetric method for the determination of ciprofloxacin hydrochloride in tablets under optimum conditions. STUDY DESIGN: Examination by spectrofluorimetry. RESULTS: The wavelengths of excitation and emission were 290 and 450 nm, respectively. The fluorescence intensity was linearly related to the drug concentration over the range 2-8 microg/mL, with a limit of detection of 1.4 microg/mL and a limit of quantitation of 2.0 microg/mL. The method was highly accurate and precise, having a relative SD of < 1.0 %. The validity of the method was tested by recovery studies of the standard addition to pharmaceuticals, and the results were satisfactory. The results obtained by the application of this method and the official one were in good agreement, and statistical comparison by Student's t test and the variance ratio F test showed no significant difference between the 2 methods. CONCLUSION: The proposed method is simple and sufficiently precise for quality control purposes.

Electrochemical investigation of 1,3,5-triphenylformazan and its nitro derivatives in dimethyl sulfoxide.

Cyclic voltammetric (CV) and chronoamperometric (CA) behaviors of 1,3,5-triphenylformazan (TPF), 3-(p-nitrophenyl)-1,5-diphenylformazan (PNF) and 3-(m-nitrophenyl)-1,5-diphenylformazan (MNF) were studied in dimethyl sulfoxide medium. TPF was found to give a single sharp cathodic CV peak corresponding to a gain of one-electron per molecule. The diffusion coefficient and the number of electrons transferred were calculated using the Baranski equation with the CV-data obtained by an ultramicroelectrode. Standard rate constants for the reduction were calculated by the Klingler-Kochi technique. The electrochemical data obtained support the mechanism proposed by Umemoto.

Liquid-membrane electrode sensitive to ammonia and aliphatic amines based on 1-[(2-oxyphenyl)iminomethly]-2-oxybenzene-O,O',N-ammin-nickel(II) complex.

In this study, an ammonia-gas-sensing liquid-state membrane electrode based on 1-[(2-oxyphenyl)iminomethyl]-2-oxybenzene-O,O',N-ammin-nickel(II) (Ni(II)-Schiff base) as an ionophore was developed. This membrane electrode gave a very good performance and exhibited linear response with near-Nernstian slope of 50.7+/-0.5 mV per decade, within a concentration range of 1.0x10(-1)-1.0x10(-3) M. The electrode performance depends on the pH of the test solution and the optimum pH range was 10.0-11.5. The effect of concentration of internal solutions in the electrode was also investigated. The selectivity properties of the electrode towards aliphatic amines at a pH value of 10.2 were investigated with the mixed-solution method. Furthermore, the response time and lifetime of the electrode prepared were determined.