The Study of Iron-based Nanoparticles Stability in Biological Fluids by Stripping Voltammetry

AbstractThe possibility of application of voltammetric methods for evaluating the stability of nanoparticles in biological fluids has been shown for the first time. The kinetics of degradation both of uncoated nanoparticles and with different coatings in a simulated solution of gastric juice in a wide range of time has been studied. It has been shown that by using carbonaceous coatings nanoparticles resistance increases 2-4 times, and when modifying the surface with aryldiazonium salts - 5-6 times

КОМБИНИРОВАННОЕ ПРИМЕНЕНИЕ БИСФОСФОНАТОВ И СТРОНЦИЯ РАНЕЛАТА С ОСТЕОЗАМЕЩАЮЩИМИ МАТЕРИАЛАМИ

In review the possibility of biomaterials osseointegration improvement with help of bisphosphonates or strontium ranelate is discussed. For this purpose, they are added to hydroxyapatite used for implants coating, or are included as a component of bulk calcium phosphate materials. Strontium is employed as a compound of biodegradable metal alloys, also. Combined use of carrier (implant) with bisphosphonates or strontium ranelate promotes controlling local delivery of pharmaceutical molecules into lesion, enhances the therapy efficiency, and decreases a dose and systemic toxicity of the drugs. Bisphosphonates and strontium ranelate increase the mass, a count and thickness of bone trabeculas, improve the bone biomechanical properties in the place of implants fixation, and diminish the bone fracture risk. Main studies are devoted to pharmacologic mechanisms of implants osseointegration improvement. Bisphosphonates as isoprenoid lipids chemical analogues diminish by concurrent principle theosteoclasts farnesyl pyrophosphate synthase activity and inhibit the prenylation. Unprenylated small GTPases don’t fasten onto osteoclasts membrane that weakens cellular resorptive activity and accelerates their apoptosis. Strontium ranelate enhances osteoblasts replicative activity and suppresses their apoptosis, also retards osteoclasts resorptive function and accelerates their apoptosis. Its effects are conditioned by activating Wnt-signaling pathway by means of calcium-sensing receptor and by changing the RANKL/RANK/OPG system. В обзоре рассмотрена возможность улучшения остеоинтеграции биосовместимых материалов с помощью бисфосфонатов или стронция ранелата. Эти лекарственные средства добавляют к гидроксиапатиту, используемому для покрытия имплантатов, включают в состав кальцийфосфатных материалов. Стронций является также компонентом биодеградируемых сплавов. Бисфосфонаты и стронция ранелат увеличивают массу, число и толщину костных трабекул, улучшают биомеханические свойства кости в месте введения имплантатов, снижают риск переломов. Большое число исследований посвящено механизмам фармакологического улучшения остеоинтеграции имплантатов. Бисфосфонаты как химические аналоги изопреноидных липидов по конкурентному принципу уменьшают в остеокластах активность фарнезилдифосфатсинтазы и тормозят пренилирование. Непренилированные малые ГТФазы не прикрепляются к мембране остеокластов, что ослабляет их резорбтивную функцию и ускоряет апоптоз. Стронция ранелат, активируя при участии кальцийчувствительного рецептора Wnt-сигнальный путь и изменяя функции системы RANKL/RANK/OPG, повышает репликационную активность и подавляет апоптоз остеобластов, а также тормозит резорбтивную функцию и ускоряет апоптоз остеокластов

Comparative investigations of structure and properties of micro-arc wollastonite-calcium phosphate coatings on titanium and zirconium-niobium alloy

Investigation results of micro-arc wollastonite–calcium phosphate (W–CaP) biocoatings on the pure titanium (Ti) and Zr–1wt.%Nb (Zr–1Nb) alloy were presented. The voltages of 150–300 V generate the micro-arc oxidation (MAO) process with the initial amplitude current of 150–550 A and 100–350 A for Ti and Zr–1Nb substrates, respectively. The identical dependencies of changes of the coating thickness, surface roughness and adhesion strength on the process voltage were revealed for the both substrates. The W–CaP coatings with the thickness of 10–11 μm were formed on Ti and Zr–1Nb under the low process voltage of 130–150 V. Elongated wollastonite particles with the size in the range of 40–100 μm were observed in such coatings. The structure of the coatings on Ti was presented by the X–ray amorphous and crystalline phases. The X–ray reflexes relating to the crystalline phases of Ti and wollastonite were observed only in XRD patterns of the coatings deposited under 130–200 V on Ti. While, the crystalline structure with phases of CaZr4(PO4)6, β–ZrP2O7, ZrO2, and Zr was detected in the coatings on Zr–1Nb. FT–IRS, XRD, SEM, and TEM data confirmed that the increase of the process voltage to 300 V leads to the dissociation of the wollastonite. No toxic effect of specimens on a viability, morphology and motility of human adipose–derived multipotent mesenchymal stem cells was revealed in vitro

Electrically Functionalized Hydroxyapatite and Calcium Phospate Surfaces to Enhance Immobilization and Proliferation of Osateoblasts In Vitro and Modulate Osteogenesis In Vivo

Hydroxyapatite (HAP) is used to fabricate implants for bone repair in dentistry and orthopaedics. To functionalise the surface of HAP that is in direct contact with human cells a surface electrical charge deposition has been achieved by means of hydrogenation technology. This technology provides uniform 3 dimensioned processing of the specimen surfaces. The engineered charge was estimated from measurements of the photoelectron emission work function (ϕ). The later was increased to ~ 0.2 eV. The negatively charged HAP surface attached 10 times more osteoblatic cells and increased their proliferation capacity 1.6 times, in contrast to the uncharged one. The above increment of ϕ had an effect on the differentiation of mesenchymal stromal cell pool (MSCP) immobilized on the calcium phosphate (CP) coatings. In vivo experiments (BALB/c mice) demonstrated that hydrogenation of CP coatings could effect MSCP differentiation into fibroblasts or osteoblasts. The technique of intracellular RNA staining detected the actively synthesizing osteoblasts and bone marrow stromal cells