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At least 19 recordsLinked to original sources
PubMed2002

Effect of different Ti-6Al-4V surface treatments on osteoblasts behaviour.

The purpose of the present work was to examine the effect of different Ti-6Al-4V surface treatments on osteoblasts behaviour. Previous work in this laboratory has demonstrated that an ageing treatment reduces metal ion release from this alloy compared to standard passivation procedures. In this study. human osteosarcoma MG-63 were used in short-term in vitro tests to assay for cell viability and cell proliferation at 12, 24 and 72 h while SaOS-2 were used in long-term in vitro tests to assay for osteonectin, osteopontin, osteocalcin gene expression, total protein amount (TP). alkaline phosphatase activity (ALP) and fibronectin production (FN) for 1-4 weeks. Epifluorescence microscopy was used to observe SaOS-2 cell morphology. After 24h, there was no difference in MG-63 cell viability proliferation or in SaOS-2 cell morphology between the different surface treatments. For the long-term tests, the aged Ti-6Al4V induced significantly higher cell proliferation than the control Ti-6Al-4V at 72h. At week 1, no difference in the osteonectin, osteopontin, and osteocalcin gene expression was found between samples. The peak of ALP activity appeared earlier at week 2 for the control surface compared with the passivated and aged surfaces. The early increase in ALP activity for the control sample could be a compensatory effect of decreased osteoblasts proliferation. There was no difference in the expression of FN for the different surface treatments. Our present results showed that the different surface treatments, which induced different metal ion release kinetics and surface properties, influenced the cell proliferation and ALP activity of osteoblast cells. Aluminium ions release kinetics as well as presence of vanadium ions may play a major role in influencing the osteoblasts behaviour in the present study.

Alkaline Phosphatase↗
PubMed2026

Proteomic insights into the immunomodulatory effects of Ca/Sr co-doped sol-gel coatings for titanium implants.

Ionic functionalization of biomaterial coatings has emerged as a powerful strategy to regulate early host responses at the implant interface. However, how combined Ca/Sr incorporation governs the adsorbed proteome and downstream immune signaling remains poorly understood. This study analyses, employing in vitro tests and proteomics, the effect of adding Sr and Ca to Si-based coatings designed to bioactivate Ti implants. Hybrid Si-based coatings were synthesized by the sol-gel route with a fixed Ca content (0.5 wt%) and increasing Sr contents (0.5, 1.0, 1.5 wt%), and their physicochemical properties, ion release kinetics, and hydrolytic stability were characterized. The coatings remained highly crosslinked despite Ca/Sr incorporation, whereas the highest Sr content increased hydrolytic degradation to around 70% after 56 days. Proteomic analysis identified 183 adsorbed proteins, of which 56 were differentially adsorbed on Ca/Sr-coatings, mainly associated with immune and coagulation pathways. In vitro, RAW 264.7 showed increased gene expression of TNF-α and TGF-β; with an enhanced TNF-α secretion by the addition of Ca and Sr. In parallel, MC3T3-E1 indicated that Ca/Sr-coatings were not cytotoxic and did not impair cell proliferation. However, ALP activity was reduced in the co-doped groups, indicating that the immunomodulatory effects induced by Ca/Sr incorporation were not accompanied by enhanced early osteogenic differentiation. The Ca/Sr combination induced alterations in the adsorption of immune-related proteins, which correlated with the in vitro findings. The deeper insight into how Ca/Sr mixtures modulate protein adsorption on biomaterial surfaces may be key to understanding the immunomodulatory capacity of these bioactive cations.

Animals↗
PubMed2003

The effect of resin particle size on the rate of ion release: interactions in mixed bed systems.

The aim of the present study is to evaluate the influence of resin particle sizes on the rate of ions release from a mixture of ion-exchange resins (named NMTD) which supplies calcium, fluoride, and phosphate ions as the main mineral content, and to elucidate the different phenomena taking place through the related ion-exchange process. The final goal of the study, related to dental application (enamel restoration), is to limit the particle size range, since the rate of ion release is a key parameter in the successful achievement of such objective. Weak-type ion-exchange resins, loaded with the appropriate ions, were ground and sieved into granulometric fractions of bead diameters of 0.1-0.075, 0.075-0.063, and 0.063-0.05 mm. Particle size was controlled by a laser diffraction particle distribution analyzer. The experiments on the kinetics of ions release were carried out under batch conditions in artificial saliva desorption solution thermostatized at 37 degrees C. The release of Ca(2+) and F(-) was determined by corresponding ion-selective electrodes automatically controlled, whereas H(2)PO(4)(-) was measured spectrophotometrically by the inductively coupled plasma-optical emission technique (ICP-OES). The results of this study show that the process of ion-exchange for the different particle size fractions of resins is critical for the study of the kinetics release of the ions immobilized in the corresponding mixed bed polymeric matrices. In fact, despite the apparent narrow range of particle sizes of the mixed bed systems studied, appreciable differences in the rate of ions release are obtained. Since the ion release rate is depending on the contact surface, an increase of factor of 2 in particle size represents an increase of an order of magnitude of the resin contact surface due to the resin porosity. In this concern, it has been observed that the rate of ions release increases when particle size decreases. The interactions occurring during the ion release from the mixed bed resins (containing calcium-, fluoride-, and phosphate-loaded resins) can be interpreted by the following phenomena: H(2)PO(4)(-), which hardly modifies its rate of release in the presence of Ca(2+) and F(-) in the mixture, promotes a considerable increase in the rate of Ca(2+) release due to the formation of a calcium dihydrogen phosphate soluble complex. F(-) also produces an acceleration in the rate of Ca(2+) release due to the formation of solid CaF(2 )on the surface of cationic resin particles, which in contrast leads to a decrease in the rate of F(-) release.

Journal Article↗
PubMed2005

Characteristics of nitrogen release from synthetic zeolite Na-P1 occluding NH4NO3.

Zeolites can accommodate a considerable amount of occluded salt such as NH4NO3, which can serve as a good source of slow-release plant nutrient. This study evaluates the kinetics of ion release from NH4NO3-occluded Na-P1 (N-NaP) using a simulated soil solution and deionized water as leaching solutions. The patterns of ion releases were examined as a function of leaching time under both static and continuous-flow conditions for more than one month. Releases of both NH4+ and NO3- from N-NaP were found to be slow and steady under both the above conditions. The soil solution affected the release of NH4+ and NO3- differently, while deionized water released nearly the same equivalents of these ions. This clearly indicates that ion release from salt-occluded zeolite involves two different reactions, cation exchange and dissolution. The kinetics of ion release from occluded NH4NO3 under static condition was best described by the standard Elovich model while the power function model best expressed these under continuous-flow condition. The initial ion release patterns under both conditions exhibited considerable deviation from the simulated models, probably as a result of the presence of hydrated occluded NH4NO3. Flow condition and the presence of electrolytes in leaching solution affected the release kinetics significantly. Release of occluded NH4NO3 was delayed by the presence of the NH4NO3 coated on zeolite crystals. These results indicate that the ion release property of occluded salt could be predicted and controlled. This study clearly shows that NH4NO3-occluded zeolites could be developed as slow release fertilizers.

Delayed-Action Preparations↗
PubMedDate not supplied

Ion-exchange albumin microcapsules of doxorubicin: an in vitro release kinetic evaluation.

Cross-linked albumin microcapsules were prepared, using a polycondensation interfacial process. Doxorubicin was incorporated in these microcapsules by simple adsorption from aqueous solution. Increasing the extent of cross-linkage of the microcapsule walls by either increasing the cross-linking agent concentration or the time of reaction significantly reduced the absorption ability of these microcapsules. Doxorubicin release kinetic evaluation revealed that the presence of a salt in the release medium was needed to enable much of the drug to be released. Furthermore, the doxorubicin displacement intensity from the microcapsules was dependent on the nature and concentration of the cations used, indicating that an ion-exchange process was involved. Analysis of the various doxorubicin release profiles, using ion-exchange kinetic equation, showed that the release kinetic process is governed by a film diffusion process at low and moderate Na+ ion concentrations in the exchanging solution, and by a particle diffusion process at high Na+ ion concentrations, sufficient to drive the doxorubicin exchange to completion.

Capsules↗
PubMed1981

Ferric ion sequestering agents: kinetics of iron release from ferritin to catechoylamides.

The removal of ferric ion from the iron storage protein ferritin to synthetic catechoylamide sequestering agents has been studied using visible spectroscopy at 487 nm. One ligand which has been investigated in detail is N,N',N' ',-tris(2,3-dihydroxy-5-sulfobenzoyl)-1,5,10-triazadecane (3,4-LICAMS), which octahedrally coordinates the metal ion via six phenolic oxygens. For some related catechoylamide chelates, the percentage of iron removed after 6 h has been determined. These ligands incorporate various modifications, either on the catechol moiety or on the backbone structure of the ligand. Mobilization of iron by the catechoylamide ligands alone results in very slow exchange, and virtually no iron removal after 6 h. In contrast, addition of ascorbic acid to the reaction mixture facilitates iron exchange, with the release of 7% of the available iron in the same time span. Variation of the initial rate with ascorbic acid concentration results in Michaelis-Menten kinetics with Km = 1.7 . 10(-3) M and a maximal rate of 1.28 . 10(-7) M . min-1. The ascorbic acid-mediated rate was not affected by changing the catechoylamide ligand concentration, and was only slightly affected by variation of the ligand employed. These data are consistent with a multistep process which includes diffusion of a reductant into the ferritin inner core, reduction and possible chelation of the ferrous ion, diffusion out of the protein shell, and subsequent iron exchange with the catechoylamide molecule.

Ferritins↗
PubMed2005

Prediction of kinetics of doxorubicin release from sulfopropyl dextran ion-exchange microspheres using artificial neural networks.

The purpose of this work was to develop artificial neural networks (ANN) models to predict in vitro release kinetics of doxorubicin (Dox) delivered by sulfopropyl dextran ion-exchange microspheres. Four ANN models for responses at different time points were developed to describe the release profiles of Dox. Model selection was performed using the Akaike information criterion (AIC). Sixteen data sets were used to train the ANN models and two data sets for the validation. Good correlations were obtained between the observed and predicted release profiles for the two randomly selected validation data sets. The difference factor (f1) and similarity factor (f2) between the ANN predicted and the observed release profiles indicated good performance of the ANN models. The established models were then applied to predict release kinetics of Dox from the microspheres of various initial loadings in media of different ionic strengths and NaCl/CaCl2 ratios. The results suggested that ANN offered a flexible and effective approach to predicting the kinetics of Dox release from the ion-exchange microspheres.

Calcium Chloride↗
PubMed1988

The effect of plasma-sprayed calcium phosphate ceramic coatings on the metal ion release from porous titanium and cobalt-chromium alloys.

Bone tissue ingrowth in porous materials is enhanced by the deposition of bioactive calcium phosphate ceramic linings onto the pore walls. These bioactive coatings can be deposited using several methods which yield a variety of coating efficiencies and thereby influence the mechanisms and kinetics of ion release from the metal. We analyzed the effect of plasma-spraying hydroxyapatite onto titanium and cobalt-chromium alloys by measuring the release of Ti, Al, V, Co, and Cr in vitro. Plasma-sprayed coatings significantly reduced the Ti and Al release from titanium-based alloy specimens. The tendencies of release from the cobalt-based specimens are less pronounced. The data substantiate that neither localized enhanced passive dissolution of metal ions nor ceramic shielding of the metal occurs. The Scanning Auger Electron Microprobe Spectroscopic data suggest that the dissipation of thermal and kinetic energy of the ceramic particle at the time of impact can produce compositional and structural changes in the metal surfaces. The resulting effects are significant for the titanium alloy but less significant for the Co-Cr alloy system.

Alloys↗
PubMed2005

[Corrosion behaviour, metal release and biocompatibility of implant materials coated by TiO2-sol gel chemistry].

Alloys based on titanium or cobalt have been used as implant materials for decades with good success. Because of their natural oxide layer these alloys reveal good corrosion behaviour. In contact with physiological solution metal release takes place, which can cause inflammation. Coatings can improve the corrosion behaviour. In this study Ti6Al4V and Co28Cr6Mo alloys, which are frequently used as implant materials, were tested. Polished discs of these alloys and polished discs, which were coated with TiO2-layers by sol-gel chemistry, were compared regarding their corrosion behaviour and metal ion releasing. The releasing of Al, V, Ti, Co, Cr and Mo was quantified by ICP-MS analysis. The TiO2-coating reduced the release of all ions except of the Al-ion. Both alloys showed a deviating kinetic of ion releasing. In addition, cell response (cell vitality, cell proliferation, endothelial marker CD31 and actin allocation) of osteoblasts and endothelial cells were investigated.

Cells, Cultured↗
PubMed2026

Copper-Containing Surface Engineering for Soft-Tissue Biomedical Devices: Structure-Function Relationships and Ion Release-Driven Biological Performance, A Systematic Review.

Copper and copper-based materials have gained increasing attention for the functional modification of implantable medical devices intended for prolonged soft-tissue contact, including vascular stents, catheters, and intrauterine devices. Owing to their broad-spectrum antimicrobial activity, redox reactivity, and involvement in angiogenesis and cellular signaling, copper-based systems offer significant potential for multifunctional surface engineering. However, achieving a balance between antibacterial efficacy, corrosion behavior, controlled ion release, and cytocompatibility remains a critical challenge. This PRISMA-compliant systematic review analyzes copper-containing materials and surface modification strategies for soft-tissue biomedical applications. A structured search of Scopus, Web of Science, and PubMed (2015-2025) identified 65 eligible studies. The review encompasses bulk copper-containing alloys, electrochemical and chemical surface modification techniques, physical vapor deposition approaches, and advanced hybrid systems integrating copper with polymers, hydrogels, or metal-phenolic networks. Across the reviewed literature, antibacterial performance was strongly dependent on copper concentration, microstructural distribution, and spatiotemporal ion release profiles. Moderate, well-controlled copper incorporation frequently improved antibacterial efficacy while maintaining acceptable hemocompatibility and cytocompatibility, particularly in vascular and blood-contacting devices. In contrast, excessive copper loading often accelerated corrosion and induced adverse cellular responses. Emerging multifunctional architectures demonstrated improved regulation of biological interactions, enabling simultaneous antibacterial, antithrombotic, and proendothelial effects. Overall, copper-based surface technologies represent a versatile platform for soft-tissue implant modification. Future translational progress will require precise control of copper release kinetics and comprehensive long-term in vivo validation to ensure safety and sustained therapeutic performance. From the authors' perspective, the most promising future direction involves multifunctional copper-based hybrid coatings capable of dynamically regulating ion release, host tissue integration, and antibacterial performance simultaneously. Strategies integrating hierarchical architectures, stimulus-responsive release systems, and clinically scalable fabrication methods are expected to play a key role in translating copper-containing surfaces from experimental concepts toward commercially viable soft-tissue biomedical devices.

Copper↗
PubMed2004

High-resolution kinetic energy release distributions and dissociation energies for fullerene ions Cn+, 42 < or = n < or = 90.

We have measured the kinetic energy released in the unimolecular dissociation of fullerene ions, Cn+ --> C(n-2)+ + C2, for sizes 42 < or = n < or = 90. A three-sector-field mass spectrometer equipped with two electric sectors has been used in order to ensure that contributions from isotopomers of different masses do not distort the experimental kinetic energy release distributions. We apply the concept of microcanonical temperature to derive from these data the dissociation energies of fullerene cations. They are converted to dissociation energies of neutral fullerenes with help of published adiabatic ionization energies. The results are compared with literature values.

Journal Article↗
PubMed1984

Isomer identification by kinetic energy release measurements using the voltage pulsed collision cell technique in mass-analysed ion kinetic energy spectrometry.

The voltage pulsing of the collision cell on a mass-analysed ion kinetic energy spectrometer allows simultaneous kinetic energy release measurements for unimolecular (T(V)), collision-induced (TCID(V)) and composite unimolecular and collision-induced (Tcomp(V)) decomposition processes in the time frame of a capillary gas chromatographic peak. The information gained by voltage pulsing sometimes allows more reliable isomer identification than by kinetic energy release measurements made in the non-pulsing mode alone. Presented are T(V), TCID(V) and Tcomp(V), and the ratio of their intensities for a number of isomeric halogenated compounds.

Hydrocarbons, Halogenated↗
PubMed1987

Silver-coated nylon fiber as an antibacterial agent.

A blend of nylon fiber and silver-coated nylon fiber (the latter known as X-static) was used in these experiments. This fiber was bactericidal when bacteria were exposed to it directly or to an extract derived from its prior incubation in salt solution. At ambient temperatures, a rapid exponential decrease of survival occurred, usually after a delay of approximately 1 h. The rate of killing (decrease of survival) increased with an increase in X-static percentage of the fiber blend, temperature of fiber extraction, concentration of Tris buffer present during extraction, and temperature at which bacteria were exposed to the extract. When bacteria were exposed to the extract at 37 degrees C as opposed to ambient temperature, there was no delay in onset of killing. Escherichia coli was generally the indicator organism tested, but comparable results were also found for Pseudomonas, Klebsiella, Staphylococcus, and Streptococcus species. The rate of killing increased with increasing silver ion concentration of the fiber extract, as determined through atomic absorption spectrophotometry. The rate of killing was greater and the onset was earlier with an extract containing silver ions from fiber than with a salt solution containing the same concentration of silver ions from silver nitrate. Studies of the kinetics of ion release suggested that X-static may be an effective, sustained-release antibacterial agent.

Delayed-Action Preparations↗
PubMed2004

High resolution measurements of kinetic energy release distributions of neon, argon, and krypton cluster ions using a three sector field mass spectrometer.

Using a newly constructed three sector field mass spectrometer (resulting in a BE1E2 field configuration) we have measured the kinetic energy release distributions of neon, argon, and krypton cluster ions. In the present study we used the first two sectors, B and E1, constituting a high resolution mass spectrometer, to select the parent ions in terms of mass, charge, and energy, and studied the decay of those ions in the third field free region. Due to the improved mass resolution we were able to extend earlier studies carried out with a two sector field machine, where an upper size limit arose from the fact that several isotopomers contribute to a decaying parent ion beam when the cluster size exceeds a certain value. Furthermore we developed a new data analysis. It allows us to model also fragment ion peaks that are a superposition of different decay reactions and thus we can determine the average kinetic energy release for all decay reactions of a given cluster ion. In a further step we used these results to determine the binding energies of cluster ions Rg(n) (n> or =10) by applying finite heat bath theory. The smaller sizes have not been included in this analysis, because the validity of finite heat bath theory becomes questionable below n approximately 10. The present average kinetic energy releases and binding energies are compared with other experiments and various calculations.

Journal Article↗
PubMed2001

Kinetic energy release distributions in mass spectrometry.

Kinetic energy releases (KERs) in unimolecular fragmentations of singly and multiply charged ions provide information concerning ion structures, reaction energetics and dynamics. This topic is reviewed covering both early and more recent developments. The subtopics discussed are as follows: (1) introduction and historical background; (2) ion dissociation and kinetic energy release: kinematics; potential energy surfaces; (3) the kinetic energy release distribution (KERD); (4) metastable peak observations: measurements on magnetic sector and time-of-flight instruments; energy selected results by photoelectron photoion coincidence (PEPICO); (5) extracting KERDs from metastable peak shapes; (6) ion structure determination and reaction mechanisms: singly and multiply charged ions; biomolecules and fullerenes; (7) theoretical approaches: phase space theory (PST), orbiting transition state (OTS)/PST, finite heat bath theory (FHBT) and the maximum entropy method; (8) exit channel interactions; (9) general trends: time and energy dependences; (10) thermochemistry: organometallic reactions, proton-bound clusters, fullerenes; and (11) the efficiency of phase space sampling.

Journal Article↗
PubMedDate not supplied

Release of K+ and H+ from poly U in aqueous solution upon gamma and electron irradiation. Rate of strand break formation in poly U.

Conductivity changes were found which followed the reaction of radiolytically generated OH radicals with the potassium salt of polyuridylic acid (poly U) in aqueous solution. After 60Co-gamma-irradiation the observed increase of conductivity at pH = 6.8 was shown to consist of the liberation of K+ ions from the stock of K+ ions electrostatically bound to the polyanion. The initial G(K+) is 36 and hence 6 times higher than the G value of OH radicals in N2O saturated solutions. At a poly U concentration of 60 mg l-1 half of the ion release occurred at 12 J kg-1 and nearly all ions are released at 40 J kg-1. The liberation of K+ is explained to be a consequence of the formation of chain breaks leading to an increase of the degree of dissociation. The rate of the ion release was studied under pulse radiolysis conditions. Because of the high G-value of counterion liberation and the use of conductivity as analytical quantity the method is very sensitive. With 6 mg l-1 poly U the rate could be measured even at a dose per pulse of 0.25 J kg-1. The kinetics of the ion release can be described in terms of two parallel first order reactions of comparable contribution with an average rate constant of 0.8 s-1 at 20 degrees C, 60 mg l-1 poly U and pH = 6.8 with a small contribution of slower components. In more acidic solutions, besides K+ ions H+ are also liberated since at low pH values bound K+ is replaced by H+. The rate of the ion release was found to increase with increasing replacement of K+ by H+ (kobs = 100 s-1 at pH = 3.4, 60 mg l-1 poly U and T = 18 degrees C). With potassium ion free polyuridylic acid the corresponding rate constant amounted to 220 s-1, nearly independent of pH. From the temperature dependence activation parameters for the ion release were derived (Ea = 57 kJ mol-1, A = 1.0 X 10(10) s-1 at pH = 6.8). Addition of p-benzoquinone at pH = 3.7 and dithiothreitol (DTT) at pH 6.8 were found to decrease the size of the conductivity changes and to increase the rate. The results show that p-benzoquinone and DTT react with poly U radicals and that these reactions prevent chain breaks and ion liberation. It is concluded that the rate determining step of the conductivity increase is the formation of strand breaks by a cleavage of poly U radicals and that this reaction is pH dependent. The pH dependence and the observed value for the activation energy was found to be in agreement with the behaviour of a model system for the earlier postulated C-4' mechanism for strand break formation of polynucleotides and DNA.

DNA↗