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The limitation in bone tissue engineering is the lack of available natural or synthetic biomaterials to replace bone tissue under need. Carbon nanotubes have great potential as bone tissue scaffolds because of their remarkable mechanical and electrical properties combined with high aspect ratio. In this work, we demonstrated for the first time a novel approach based on the sol-gel technique for functionalization of multi-walled carbon nanotubes (MWCNTs) with two amino acids: L-arginine, L(+) Arg and L-aspargine, L(+) Asp. We have examined the effect of both functionalities on physicochemical properties of MWCNTs, cytotoxicity in osteosarcoma MG63 and normal fibroblastic BJ cells and the ability to induce nucleation and growth of hydroxyapatite (HA) crystals in vitro under physiological concentrations of Ca2+ and PO4+ (SBF). The scaffolds were characterized using Fourier transform infrared spectroscopy (FTIR-ATR), dynamic light scattering technique (DLS), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The results showed that both functionalized MWCNTs have a particle size of 269 and 411 nm, a zeta potential of -12.8 and -8.8 mV, respectively, high colloidal stability, enhanced biocompatibility, and enhanced formation of an apatite layer on the scaffolds surface in comparison to ox-MWCNTs. Altogether, the results confirmed the important role of the amino acids L(+) Arg and L(+) Asp in ox-MWCNTs-based composites for bone tissue engineering applications. [ABSTRACT FROM AUTHOR]

This work deals with preparation and characterization of novel grafted multi-walled carbon nanotubes (MWCNTs) with dodecenyl succinic anhydride (DSA) in presence of plant extract ( Beta vulgaris) and hydroxyapatite nanoparticles (HA). Moreover, cytotoxicity and antioxidant activity of the prepared nanocomposites using Ehrlich ascites carcinoma cells (EACC) were examined and evaluated. The prepared nanocomposites were characterized using Fourier transform infrared spectroscopy (FTIR) and transmission electron microscope (TEM). In addition to the particle size and zeta potential were recorded. The grafting technique was significantly enhanced the nanotube dispersibility and long term stability in the aqueous solution. The results indicated that the conjugation between B. vulgaris extract, HA nanoparticles and functionalized MWCNTs exhibited great antioxidant activity through the scavenging of the free radicals using DPPH assay. Also, the encapsulated B. vulgaris extract within the grafted MWCNTs based nanocomposites exhibited acceptable effect on the viability of EACC in compared with the standard (Vincrestine®). In other words, these novel functionalized MWCNTs based nanocomposites could be used as antioxidant and antitumor agents in the future after further studies. [ABSTRACT FROM AUTHOR]

Abstract: A novel carbon paste electrode based on functionlized multi-walled carbon nanotubes/β-cyclodextrin composite (FMWCNTs/β-CD-CPE) is described for potentiometric determination of piroxicam (PXM). Improved sensitivity and selectivity was achieved by application of CDs as molecular host–guest recognition elements and MWCNTs. The electrochemical performance of carbon paste electrodes incroporated with FMWCNTs/β-CD composite was compared to those incroporated with MWCNTs and free CDs. Matrices compositions of each electrode are optimized on the basis of nature and content of the modifier, ionic sites and selected plasticizer. CPEs containing FMWCNTs/β-CD composite, hyamine (Hy) and 2-fluorophenyl 2-nitrophenyl ether (f-NPE) as electrode plasticizer, work satisfactory in the concentration range from 10−6 to 10−2 molL−1 with Nernstain compliance (58.7±0.9mVdecade−1 activity) with fast response time of about 2s and exhibit adequate operational lifetime (16 weeks). The developed electrodes have been applied for the potentiometric determination of PXM in pharmaceutical formulation under batch and flow injection analysis (FIA). FIA allows the analysis of 120samplesh−1 with the advantage of simplicity, accuracy and automation feasibility. [Copyright &y& Elsevier]