Papers by Keyword: Carboxyl Group

Abstract: This article discusses the possibility of the fabrication of a highly sensitive sensor based on single-walled boron-carbon BC₅ nanotubes surface modified with functional carboxyl groups (-COOH). The sensor potential for detection of alkali (lithium, potassium, and sodium) metals were investigated. The results of computer simulation of the interaction process between the sensor and an arbitrary surface of the modified tube containing atoms of the studied metals are presented. The carboxylated BC₅ nanotube and a similarly modified BC₃ nanotube was compared. The effect of boron atoms on sensory properties of the obtained system is concluded. The calculations were carried out within the framework of the density functional theory (DFT) method using the molecular cluster model. It has been proved that surface-modified boron-carbon nanotubes by carboxyl group show high sensitivity for the metal atoms under study and can be used as the sensor device.

Abstract: This article provides a theoretical study of the possibility of reacting acetone, a common volatile organic compound (VOC) in human respiration, with carbon nanotubes modified with functional groups - carboxyl and amine. Analysis of efficiency of processes of sorption interaction of acetone molecule with modified nanosystem for development of recommendations for creation of perspective highly sensitive sensory devices using modified carbon nanotubes for detection of VOCs contained in human exhalation and diagnostics of various diseases.

Abstract: The purpose of this article is to synthesize the thiol-and carboxyl-bifunctionalized mesoporous silica nanoparticles (CMS-SH-COOH). CMS-SH-COOH was successfully synthesized by co-condensation and post-grafting methods. Moreover, the particle size and structural properties of CMS-SH-COOH were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FT-IR). The obtained results indicated that the CMS-SH-COOH presented a uniform spherical shape with a wormhole arrangement of the mesopores and a relatively narrow paticle distribition. Therefore, the CMS-SH-COOH might be a great potential carrier for the drug delivery system in the future.

Abstract: Apatite-polymer hybrid has attractive features as novel bone substitutes such as both ability of bone-bonding and mechanical performances analogous to those of natural bone, i.e. high strength and high flexibility. As a method for development of such hybrids, biomimetic process has been proposed, where apatite formation is induced on the surfaces of organic substrates at ambient conditions in simulated body fluid (SBF) with ion concentrations similar to those of human extracellular fluid, or related solutions supersaturated with respect to the apatite. In this process, heterogeneous nucleation of apatite is triggered by specific functional groups. This apatite nucleation is enhanced by release of calcium ions (Ca2+) from the materials which increases degree of supersaturation of surrounding fluid with respect to apatite. In the present study, we attempted to prepare apatite-polyamide hybrids by biomimetic process. Polysaccharides and natural polypeptides containing carboxyl group (-COOH) were used as a starting material, and apatite formation ability was compared. It was found that the apatite formation was governed by not only content of the carboxyl group but also ionic interaction with Ca2+.

Abstract: Natural bone is a kind of organic-inorganic hybrid composed of collagen and apatite crystals with a structure that provides specific mechanical properties such as high fracture toughness and flexibility. Materials exhibiting both high flexibility and bioactivity similar to natural bone are required for novel bone-repairing materials in medical fields. We expect that we can design such materials by mimicking the bone structure. Biomimetic process has been paid much attention where bone-like apatite is deposited on organic polymers in simulated body fluid (SBF). In this study, we investigated influence of cross-linking agents on apatite-forming ability of pectin gels. Pectin is a polysaccharide abundant in carboxyl group. Pectin gels were prepared by cross-linking of pectin aqueous solutions with calcium ions or divinylsulfone (DVS). Apatite-forming ability of the gels was examined in SBF. The citrus-derived pectin showed tendency to form the largest amount of the apatite independent on a kind of cross-linking agents in SBF.

Abstract: We developed a device that makes possible the normal production of low-temperature plasma under atmospheric pressure. For plasma generation, a radio frequency of rf (13.56MHz) was used. From the Fourier transform infrared (FT-IR) analysis, the absorption peak of C=O (the carbonyl group) was observed around 1715 cm-1, and the absorption peak of CH was observed around 2950 cm-1. Of those, from the conclusion that the absorption peak of C=O was proportional to the amount of CO2 added, we discovered that the C=O carbonyl group originated from the CO2 molecules.

Abstract: Apatite-polymer hybrids are expected as novel bone substitutes exhibiting bone-bonding ability and mechanical performances analogous to those of natural bone. In this study, we attempted preparation of organic-inorganic hybrids from different pectins such as pectic acid, apple-derived pectin and citrus-derived pectin through apatite deposition in simulated body fluid (SBF). Pectin gels were prepared by CaCl2 treatment of aqueous solutions of pectin. Apatite-forming ability of the gels was examined in SBF. The citrus-derived pectin showed tendency to form the largest amount of the apatite in SBF.

Abstract: Development of the organic-inorganic hybrids composed of apatite crystals and organic polymer is expected to be an attractive material that has mechanical properties similar to natural bone as well as bone-bonding ability, i.e. bioactivity. It is reported that the carboxyl groups (-COOH) on the surfaces of the organic substrates act as a catalyst for induction of heterogeneous nucleation of apatite. The present authors previously showed that the apatite was successfully deposited on the polyglutamic acid gels containing abundant carboxyl groups through the biomimetic process, when they were priorly treated with calcium chloride solution. In this study, we fabricated the polyglutamic acid gels with different degree of cross-linking. Effect of the cross-linking on their ability of the apatite formation was examined in simulated body fluid (SBF). It was suggested that the apatite deposition on the polyglutamic acid gels is governed not only by the amount of –COOH that induces the heterogeneous nucleation of the apatite, but also by swelling property that controls local increase in degree of supersaturation with respect to the apatite.

Abstract: We developed a device that makes possible the normal generation of low-temperature plasma under atmospheric pressure. For plasma generation, a radio frequency of rf (13.56 MHz) was used, for plasma gas, helium (He), and for material gases, acetylene (C2H2) and toluene (C6H5CH3) were used. As a result of measuring Fourier transform infrared (FT-IR) after adding the CO2 gas to the generated plasma, the absorption of C=O (carboxyl group) was observed around 1715 cm-1. When the flow rates of the added CO2 increased, the absorption peak increased at the same time, and we knew that this originated from the CO2 molecules.

Abstract: Apatite formation on polyamide films containing either carboxyl or sulfonic groups was compared in 1.5SBF, whose ion concentrations are 1.5 times those of a simulated body fluid (SBF). The sulfonic groups induced the apatite nucleation earlier than the carboxyl groups. In contrast, the rate of crystal growth depended not on the kind of functional group, but on the degree of supersaturation of the surrounding solution. The more ready association of sulfonic groups with calcium ions may lead to earlier apatite nucleation than that of carboxyl groups. Adhesive strength of the apatite layer to polyamide film containing sulfonic groups was significantly lower than that with carboxyl groups depending on the chemical interactions as well as on the mechanical properties of the polyamide film.