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Chemical binding
About: Chemical binding is a research topic. Over the lifetime, 1822 publications have been published within this topic receiving 52516 citations.
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TL;DR: A review of existing biocompatible resorbable inorganic materials for regenerative medicine can be found in this article, where the authors consider physicochemical principles of the preparation of such materials with the use of synthetic starting powders and natural materials.
Abstract: Methods that are used in regenerative medicine rely on the inherent ability of living organisms to regenerate their tissue. If the size (volume) of a defect exceeds some critical level, regeneration can be initiated and maintained using resorbable porous scaffolds made of natural, artificial, or synthetic materials capable of temporary defect compensation. When modified with pharmaceutical products and specific proteins or cells, such porous scaffolds are referred to as tissue engineering constructs. Inorganic resorbable materials are most frequently used for bone tissue defect repair. Natural bone is a composite having a polymer (collagen) matrix filled with calcium phosphate nanocrystals in the form of insoluble calcium hydroxyapatite. For this reason, calcium phosphate-based materials are leaders of medical inorganic materials research. To date, resorbable biocompatible materials based on tricalcium phosphate, calcium pyrophosphate, brushite, monetite, and octacalcium phosphate have been developed. Calcium hydroxyapatite is known as an inorganic ion exchanger. Because of this, the composition of bone tissue includes, in addition to phosphate and calcium ions, carbonate, silicate, and sulfate ions, as well as sodium, potassium, magnesium, iron, strontium, zinc and some other metal ions. The fact that bone tissue contains anions substituting for orthophosphate ions or hydroxide ions in the calcium hydroxyapatite of bone tissue prompted researchers to produce resorbable materials based on calcium sulfates, calcium carbonate, and calcium phosphates in which orthophosphate ions are replaced by anions mentioned above. Cation substitutions in calcium hydroxyapatite of bone tissue and the chemical composition of the medium of an organism allow one to produce and use resorbable materials for bone implants consisting of cation-substituted calcium phosphates and calcium–biocompatible cation double phosphates, such as sodium-substituted tricalcium phosphate, potassium-substituted tricalcium phosphate, sodium rhenanite, potassium rhenanite, and calcium magnesium double pyrophosphate. The resorption of an inorganic material intended for use as a pharmaceutical product can be controlled via designing a preset phase composition. The above-mentioned biocompatible resorbable phases can be used in various combinations in already existing composite materials or composites under development. The microstructure of a biocompatible resorbable inorganic material can be formed as a result of various physicochemical processes. The phase composition and microstructure of a ceramic material are determined by solid-state and liquid-phase sintering processes, as well as by heterogeneous chemical reactions during firing. The phase composition and microstructure of cement stone are formed as a result of chemical binding reactions initiated by the addition of water or aqueous solutions. Amorphous materials can be prepared via melting of starting reagents or sol–gel processing. The osteoconductivity of a biocompatible resorbable inorganic material is an important property necessary for body fluids and bone cells to be able to penetrate into the implant material. Macroporosity, which determines the osteoconductivity of a resorbable inorganic material, can be produced using various technological approaches. 3D printing methods make it possible to obtain materials with tailored phase composition and microstructure and permeable macroporosity of preset architecture. A large surface area of a porous inorganic material is thought to be a factor of controlling the resorption rate. This review summarizes information about existing biocompatible resorbable inorganic materials for regenerative medicine and considers physicochemical principles of the preparation of such materials with the use of synthetic starting powders and natural materials.
12 citations
Patent•
02 May 2008
TL;DR: In this article, a graft copolymer of a self-doped conducting polymer and an organic opto-electronic device comprising a conducting polymer film formed of the above-mentioned composition are connected to each other via chemical binding.
Abstract: Provided are a conducting polymer film composition comprising a graft copolymer of a self-doped conducting polymer and an organic opto-electronic device comprising a conducting polymer film formed of the above-mentioned composition In the graft copolymer, the conducting polymer and a polyacid are connected to each other via chemical binding Therefore, the composition of the present invention can be used in organic opto-electronic devices with minimal or no dedoping occurring from heat generated inside the device As a result, the present invention can improve efficiency and life-time of the organic opto-electronic device
12 citations
TL;DR: Covalently bonded β-glucosidase, via glutaral- dehyde previously bonded to silanized silica, had a higher yield of immobilized enzyme as well as higher activity and substrate affinity in comparison to the one physically adsorbed.
Abstract: In this study, the immobilization of β-glucosidase onto mesoporous silica support by physical adsorption and covalent binding was investigated. The immobilization was performed onto micro-sized silica aggregates with an average pore size of 29 nm. During physical adsorption, the highest yield of immobilized β-glucosidase was obtained with an initial protein concentration of 0.9 mg mL -1 . The addition of NaCl increased 1.7-fold, while the addition of Triton X-100 decreased 6-fold adsorption yield in comparison to the one obtained without any addition. Covalently bonded β-glucosidase, via glutaral- dehyde previously bonded to silanized silica, had a higher yield of immobilized enzyme as well as higher activity and substrate affinity in comparison to the one physically adsorbed. Covalent binding did not considerably change pH and temperature stability of the obtained biocatalyst in range of values that are commonly used in reactions in comparison to the unbound enzyme. Further- more, covalent binding provided a biocatalyst that retained over 70 % of its activity after 10 cycles of reuse.
11 citations
TL;DR: In this article, the main raw material composites with kaolin clay, wood ash and glass waste for the production of regular ceramics were sintered at temperatures of 1000°C, 1100¼C, 1200¼c, 1250 ¼C and 1300 ¼c. After sintering process, the mixtures were analyzed by XRD, SEM, EDS and LAMMA methods been observed synthesizing of mainly amorphous vitreous materials with inclusion of new minerals mullite 2Al 2 O 3 ·3SiO 2 and graphite
11 citations
01 Jan 2006
TL;DR: In this paper, a new concept for mediating action of humic substances (HS) in the contaminated environment is developed, which defines three scenarios of mitigating activity of HS in the system "living cell-ecotoxicant".
Abstract: A new concept for the mediating action of humic substances (HS) in the contaminated environment is developed. It defines three scenarios of mitigating activity of HS in the system "living cell-ecotoxicant". The first scenario refers to deactivation of ecotoxicants (ET) by HS due to formation of non-toxic and non-bioavailable complexes. It takes place outside of the cell and is defined as "exterior effects". The second scenario refers to deactivation of ET due to HS adsorption onto the cell wall or membrane and is defined as "boundary effects": sorption takes place on the cell surface and implies changes in permeability and structure of the cell membrane. The third scenario refers to amelioration of contaminant toxicity due to activation of systemic resistance to chemical stress. This implies HS participation in immune response activation and is defined as "interior" effects. Viability of this concept was confirmed by the results of detoxification experiments. It was shown that chemical binding ("exterior effects") played a key role in ameliorating toxicity of ecotoxicants (Hg(II) and PAHs) strongly interacting with HS, whereas enhanced immune response ("boundary and interior" effects) was much more operative for a decrease in toxicity of atrazine weakly interacting with HS. The formulated concept provided satisfactory explanations for a vast pool of reported findings of mitigating activity of HS reviewed in the chapter. Few cases of amplified toxicity reported for weakly interacting contaminants in the presence of low molecular weight HS were related to facilitated penetration and follow up dissociation of humic- contaminant complexes in the cell interior. It is concluded that the developed concept can be used as a prospective tool for both predictive modelling of
11 citations