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Bioactive ions (Mg, Sr, Zn) doped carbonated hydroxyapatite powders (dHAp) and pure carbonated hydroxyapatite (HAp) powders were prepared by wet chemical precipitation method. The bioactive ions were incorporated into the HAp matrix by co-precipitation from solution containing the appropriate amount of chloride salt of different ions. The morphology of pure HAp was mainly needle-like in nanometre size and the particles were disordered showing quasi-amorphous structure. The ion doping changed the morphology of particles, the dHAp particles had distorted spheroid shapes. Owing to the ion addition, the crystallinity of particles decreased. Particle aggregations can also be observed in both types of samples. HAp and dHAp loaded biopolymer polyvinylpyrrolidone (PVP) composite materials have also been developed by novel electrospinning technique. It has been shown that both the HAp and dHAp particles can be successfully incorporated into the PVP fibre web matrix and simultaneously the bioceramic powders were attached to the surface of polymer fibres. The surface of fibres was not fully covered with the particles. The ceramic powder addition to the polymer solution caused the polymer fibres to become more entangled and the diameters of fibres varied over a wider range compared to the base polymer fibres without bioceramic powder addition.

Extracellular vesicles (EVs) are released during the storage of red blood cell (RBC) concentrates and might play adverse or beneficial roles throughout the utilization of blood products (transfusion). Knowledge of EV release associated factors and mechanism amends blood product management. In the present work the impact of storage time and medium (blood preserving additive vs isotonic phosphate buffer) on the composition, size, and concentration of EVs was studied using attenuated total reflection infrared (ATR-IR) spectroscopy, microfluidic resistive pulse sensing (MRPS) and freeze-fraction combined transmission electron micrography (FF-TEM). The spectroscopic protein-to-lipid ratio based on amide and the C–H stretching band intensity ratio indicated the formation of various vesicle subpopulations depending on storage conditions. After short storage, nanoparticles with high relative protein content were detected. Spectral analysis also suggested differences in lipid and protein composition, too. The fingerprint region (from 1300 to 1000 cm−1) of the IR spectra furnishes additional information about the biomolecular composition of RBC-derived EVs (REVs) such as adenosine triphosphate (ATP), lactose, glucose, and oxidized hemoglobin. The difference between the vesicle subpopulations reveals the complexity of the REV formation mechanism. IR spectroscopy, as a quick, cost-effective, and label-free technique provides valuable novel biochemical insight and might be used complementary to traditional omics approaches on EVs.

TiO2-C (carbon) hybrid materials are promising electrocatalyst supports because the presence of TiO2 results in enhanced stability. Use of new types of carbonaceous materials such as reduced graphene oxide (rGO) instead of traditional active carbon provides certain benefits. Although the rutile polymorph of TiO2 seems to have the most beneficial properties in these hybrid materials, the anatase type is more frequent in TiO2-rGO composites, especially in graphite oxide (GO) derived ones, as GO has several properties which may interfere with rutile formation. To explore and evaluate these peculiarities and their influence on the composite formation, we compared TiO2-C systems formulated with GO and Black Pearls (BP) carbon. Various physicochemical methods, such as attenuated total reflection infrared (ATR-IR)-, solid state NMR-, Raman- and X-ray photoelectron spectroscopy, X-ray powder diffraction (XRD), electron microscopy, etc. were used to characterize the samples from the different stages of our multistep sol-gel synthesis. Our experiments demonstrated that utilization of GO is indeed feasible for composite preparation, although its sodium contamination has to be removed during the synthesis. On the other hand, high temperature treatment and/or solvothermal treatment during composite synthesis resulted in decomposition of the functional groups of the GO and the functional properties of the final product were similar in case of both composites. However, Pt/TiO2-GO derived sample showed higher oxygen reduction reaction (ORR) activity than Pt/TiO2-BP derived one. Based on the decrease of electrochemical surface area, the stability order was the following: Pt/C (commercial) < Pt/TiO2-BP derived C < Pt/TiO2-GO derived C.

The hardly water-soluble curcumin with low bioavailability was successfully encapsulated into biodegradable polymeric particles by nanoprecipitation. By using the more hydrophobic poly(ε-caprolactone) (PCL) instead of poly(lactic-co-glycolic acid) 50:50 (PLGA) significantly increased drug load was achieved. The stronger interaction between curcumin and PCL than PLGA was supported by Fourier-transform infrared spectroscopy (FTIR) measurements. As efficient colloid stabilizer, a novel amphiphilic polymer, hyperbranched polyglycerol with one long alkyl chain (C18-HbPG) was used which has better membrane affinity than the widely used Pluronics, and it enables further functionalization of the drug carrier as well. A Box-Behnken experimental design was applied to prepare and optimize the properties of curcumin loaded PCL nanoparticles (NPs) varying the initial drug load, composition of the organic phase and volume ratio of aqueous and organic phases. The volume of the organic phase was found to be the most relevant parameter for encapsulation, and it can be used to control the size and drug content of the NPs. The curcumin load of 10 w/w% of the NPs with diameter below 120 nm was observed in the optimal system. Cumulative controlled release of curcumin with strong pH-dependence into simulated gastric fluids with up to ~80% is found after 8–12 hours.

The influence of the semiconductor microstructure on the photocatalytic behavior of Pt-PtOx/TiO2 catalysts was studied by comparing the methanol-reforming performance of systems based on commercial P25 or TiO2 from sol–gel synthesis calcined at different temperatures. The Pt co-catalyst was deposited by incipient wetness and formed either by calcination or high-temperature H2 treatment. Structural features of the photocatalysts were established by X-ray powder diffraction (XRD), electron spin resonance (ESR), X-ray photoelectron spectroscopy (XPS), optical absorption, Raman spectroscopy and TEM measurements. In situ reduction of Pt during the photocatalytic reaction was generally observed. The P25-based samples showed the best H2 production, while the activity of all sol–gel-based samples was similar in spite of the varying microstructures resulting from the different preparation conditions. Accordingly, the sol–gel-based TiO2 has a fundamental structural feature interfering with its photocatalytic performance, which could not be improved by annealing in the 400–500 °C range even by scarifying specific surface area at higher temperatures.

Magnetic nanoporous silica particles (MNS) with spherical morphology and 100 nm particle with advanced characteristics suitable for nanomedicine purposes were synthesized. The obtained nanoparticles were modified with SO3H groups in a two-step post synthesis procedure. An anticancer drug, mitoxantrone (MTX), and an anti-inflammatory drug, prednisolone (PRD), were loaded on the silica support. The mitoxantrone loaded MNS-SO3H nanoparticles were coated by chitosan and then prednisolone was infused in the chitosan layer. A second layer of alginate was then applied around the prednisolone and mitoxantrone containing formulation. All materials were characterized by XRD, N2 physisorption, Mossbauer spectroscopy, magnetization measurements and transmission electron microscopy in order to demonstrate that by the applied preparation method around 11 nm sized maghemite crystals embedded in spherical mesoporous silica nanoparticles were obtained with high pore volume and surface area. Thermal gravimetric analysis, ATR FT-IR spectroscopy and in vitro release experiments proved that MTX and PRD were successfully loaded on the silica matrix. Alginate coating further improved the release properties by preventing the burst release of MTX and PRD. The cytotoxicity properties of the drugs loaded formulations and their ability to retain the intrinsic pharmacological properties of the encapsulated drugs were investigated on a panel of human tumor cell lines.

Graphite-oxide/TiO2 (GO/TiO2) composite materials were prepared by heterocoagulation method from Brodie’s graphite-oxide (GO) in order to test them as catalysts in the methanol photocatalytic reforming reaction in liquid phase. The preparation of the composite itself resulted in only little changes in the structure of GO as it was indicated by attenuated total reflection infrared (ATR-IR) and 13C magic-angle spinning nuclear magnetic resonance (13C MAS NMR) spectroscopic measurements. However, during the photocatalytic reaction, all of the GO/TiO2 samples darkened strongly indicating structural changes of GO. X-ray photoelectron spectroscopy along with NMR confirmed the loss of oxygen functionalities and emergence of graphitic species in the samples recovered from the photocatalytic reaction. Model experiments were designed to identify the key factors determining the activity of the GO/TiO2 derived photocatalysts. It was found that the emergence of a pronounced coupling between TiO2 and the graphite-like carbonaceous material is the most important contribution to get active and stable photocatalysts.

Vibrational spectroscopic study of crystalline copper hexacyanoferrate complexes of composition K4CuII6 [FeII(CN)6]4·nH2O (1) and CuII6[FeIII(CN)6]4·nH2O (2) with -Cu-N≡C-Fe- bridging structures ha...

Effects of modification of PtO x -TiO 2 photocatalysts by tin were elucidated by exploring relationships between the structural properties of variously prepared tin-loaded catalysts and their catalytic activity in methanol photocatalytic reforming. Tin free and amorphous tin-oxide decorated TiO 2 samples were prepared by sol-gel method from titanium-isopropoxide. In other approach, Sn was loaded onto the sol-gel prepared TiO 2 by impregnation followed by calcination. Pt was introduced by impregnation followed by either reduction in H 2 at 400 °C or calcination at 300 °C. TEM, XRD and Raman spectroscopic measurements proved that TiO 2 existed in the form of aggregates of polycrystalline anatase with primary particle size of 15–20 nm in all samples. Photocatalytic hydrogen production was influenced by the combined effect of many parameters. Both the presence of Sn and the way of Pt co-catalyst formation played important role in the activity of these photocatalysts. The Sn introduction by both sol-gel method and impregnation clearly enhanced the photocatalytic activity. 1 H MAS NMR measurements revealed that the Sn introduction reduced the amount of the terminal Ti-OH groups of relatively basic character considered to be unfavorable for the photocatalytic reaction. Presence of SnO x decreased the signal of the undesirable vacancies observed by ESR. Furthermore surface SnO x enhanced the dispersion of Pt. Formation of the Pt co-catalyst by calcination was more favorable than by H 2 treatment. In case of the calcined samples in situ reduction of the Pt nanoparticles at the beginning of the photocatalytic reaction was found to be favorable for the hydrogen production. The relatively modest photocatalytical activity obtained after high temperature H 2 treatment could be related to at least two processes in this system: (i) creation of unfavorable oxygen vacancies and (ii) segregation of SnO x to the surface of the Pt cocatalyst as the result of the air exposure of the alloy type Pt-Sn nanoparticles formed during the H 2 treatment, resulting in a decreased number of active sites for reduction of H + .

New composite materials based on clay minerals had been prepared by reductive calcination. These materials exhibit very strong infrared (IR) emission at quite low temperatures. The structural prope...

A peculiar polygonal protein scaffolding that resembles to spectrin-based skeleton of red blood cells can be reconstructed on the outer surface of vesicle-like nanoerythrosomes. The approximately 130 nm sized nanoerythrosomes are produced from red blood cell ghosts by addition of phospholipids (dipalmitoylphosphatidylcholine, DPPC). The scaffolding, constructed from the structural proteins of the cell membrane skeleton, covers the whole object resulting an enhanced stiffness. The protein pattern of the scaffolding is thermosensitive, reversible transformable in the biologically relevant temperature range. When the lipid additive is changed from DPPC to lysophospholipid (LPC), the protein network/scaffolding ceases to exist. By the variation of lipid type and ratio, a tailoring of the nanoerythrosomes can be achieved. During the tailoring process nanoerythrosomes or micelles, in a wide size range from 200 to 30 nm, are produced.

SBA-16 and MCM-41 silica materials were synthesized and modified by post-synthesis method with different amounts of Zn (2 and 4 wt.%). Quercetin, a flavonol compound, was loaded by incipient wetness impregnation method on the pure silica and Zn-modified mesoporous MCM-41 and SBA-16 supports. The parent and drug loaded formulations were characterized by powder XRD, N2 physisorption, thermal analysis, TEM, UV Vis and FT-IR spectroscopies. The formation of Zn:quercetin complex was studied by FT-IR spectroscopy and quantum-chemical calculations. Loading of quercetin on mesoporous carriers made the sustained delivery of the bioactive compound possible in a buffer with pH = 5.5, typical of dermal formulations. The results from the release experiments are in good accordance with the interaction energy between the bioactive molecule and non-modified and Zn-modified mesoporous materials, predicted by the quantum-chemical calculations. For the first time the formation of the most stable Zn quercetin complexes loaded on the mesoporous silica materials were determined. The obtained mesoporous delivery systems with Zn-quercetin complex are promising as dermal formulations.

Prednisolone loaded mesoporous silica nanocomposites with different amounts of maghemite core were prepared to design a drug delivery system suitable for drug administration in magnetic field. Textural investigations evidenced that 80–150 nm sized spherical particles with 3–3.5 nm pore size are formed by the applied synthesis method, varying with the amount of incorporated magnetic particles. Mossbauer spectroscopic results proved the presence of small maghemite nanoparticles inside the silica structure. Fourier transform infrared and Raman spectroscopic measurements provided data about the interaction between the drug and the silica, and revealed the polymorphic nature of prednisolone. Spectroscopic data suggested weak bonding between silanol groups of the mesoporous silica nanoparticles and prednisolone molecules. By the applied drug loading method polymorphic transformation of the parent Form I prednisolone occurred. In vitro release process at pH 7 showed lower solubility of polymorphic Form II compared to Form I. Slower release of prednisolone was observed by silica loaded formulations, reaching total amount in 10 h. The effect of prednisolone polymorphs loaded in silica carrier on its pharmacokinetic properties was studied for the first time.

Silver loaded nanosized zeolite Beta was prepared by a simple, mechanochemical method. Sulfadiazine (SD) drug was also deposited on silver Beta zeolite by the same method to get a bicomponent, sustained release antibacterial formulation. FT-IR spectroscopic investigations evidenced the incorporation of silver ions into the zeolite framework, i.e. occurrence of solid-state ion exchange (SSIE). The mechanism of SSIE was studied by thermo-gravimetric-mass spectrometric analysis. Formation of metallic silver nanoparticles stabilized on the surface of zeolite particles was supported by X-ray powder diffraction and UV spectroscopic methods. Our experiments revealed that Beta zeolite nanoparticles were able to store and release the loaded SD, together with the supported Ag. In vitro release studies in phosphate buffer (pH=5.5) demonstrated that the concomitant presence of Ag and sulfadiazine influenced the release kinetics of both components. The potential of combined antibacterial action of the novel silver-based zeolite-sulfadiazine composite as drug delivery system has been tested using Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Streptococcus pyogenes strains as model. The presence of silver in the developed formulations led to enhanced bactericidal effect on the studied strains.

The problems related with low solubility and instability in physiological environment of flavonoids are currently a challenge for their potential application for prevention and therapy of major chronic diseases, including cardiovascular and neurodegenerative diseases, cancer etc. Promising approach to overcome these drawbacks is incorporation of these compounds into mesoporous silica carriers. In this study we develop SBA-16 silica nanoparticles modified by a post-synthesis method with Mg (4 wt.%) or Ag (4 wt.%) as a carriers for simultaneous delivery of poorly soluble biological active compounds and essential micronutrients or antimicrobial agents. Hesperetin, a natural flavonone, and morin, a natural flavonol, belong to the big family of flavonoids were loaded by incipient wetness impregnation on the parent and Ag- or Mg-modified mesoporous supports. The initial, modified and drug loaded SBA-16 materials were characterized by powder XRD, N2 physisorption, thermogravimetric analysis and SEM measurements. The interactions between metals, silica surface and flavonoids were studied by ATR-FTIR and UV–Vis spectroscopies. Improved release profiles are observed for flavonoids loaded in mesoporous materials in comparison with pure flavonoids. Loading of flavonoids in parent and modified mesoporous carriers made the sustained delivery of the bioactive compound possible. A comparative study on anti-proliferative effect of the tested flavonoids loaded into modified silica carriers vs. free drug was investigated on a panel of three human cell lines. The evaluation of the antioxidant capacity shows that loading of the flavonoids into parent and modified silica supports can improve their activity against free radicals, which could be explained by the improved solubility of the loaded flavonoids in comparison with the pure ones. The obtained mesoporous delivery systems are promising as oral formulations for delivery of flavonoids, essential microelements and antimicrobial agents.

Silica@zirconia@poly(malic acid) nanocarriers of 110 nm mean diameter were designed, synthesized and characterized for the targeted delivery of diagnostic and therapeutic 99mTc to folate-overexpressing tumors. An important achievement was that a multifunctional L-(−)-malic-acid-based copolymer was formed in situ at the surface of the inorganic cores in a single synthetic step incorporating L-(−)-malic acid, β-cyclodextrin rings, folic acid moieties, and polyethylene glycol chains. Morphological and in-depth structural analysis of the particles proved their core@shell structure. Stability experiments in aqueous media evidenced that stable suspensions can be obtained from the lyophilized powder in 10 mM phosphate buffer at pH 7.4. During 14-day degradation experiments, the nanoparticles were found to be slowly dissolving (including inorganic core) in saline and also in total cell medium. An in vitro toxicity assay on hepatocytes showed a concentration-dependent decrease of cell viability down to 63 ± 1% at the highest applied concentration (0.5 mg ml−1). Proof of concept experiments of technetium-99m radiolabelling and in vivo labelling stability are presented.

A one-pot synthesis of stereomer cross-linked copolymers of l-malic acid with tuned properties is reported. The β-cyclodextrin, as co-monomer with several OH groups, was applied to promote the polyester formation with higher, pre-defined molecular weight. The importance of the experimental conditions for preparation of polymers with tailor-made, optically active compositions is described, and their structures are characterized by different techniques such as thermogravimetry–differential scanning calorimetry−mass spectrometric evolved gas analysis, infrared spectroscopy and specific rotation. To our knowledge, first time was used the specific optical rotation for characterization of retention of the optical activity in the course of the synthesis.

The newly developed zinc-rich hybrid paints are composed of polypyrrole (PPy) and polystyrene-sulfonate (PSS) modified alumina hydrate and either purified or functionalized multi-walled carbon nanotubes (MWCNTs). Preparation of the nano-size particles, i.e., in situ polymerization and deposition of PPy-PSS complexes on the mixture of alumina hydrate and MWCNTs is presented. Characterization of the particles by cyclic voltammetry (CV), Fourier-transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) as well as their dispersions by rheology investigation is detailed in this part of the work. High electrochemical reversibility, increasing electrical conductivity and Coulombic efficiency of the particles with greater relative amount of the MWCNTs were evinced. Thin layer polymer deposition was found continuous on alumina and the MWCNTs and varied compactness of the PPy films and charge-delocalization over their network were witnessed depending on the proportion of incorporated PSS. Different micron-scale dispersity of the particles, compactness and ramification of particle clusters as well as their aggregation at nano-scale and flocculation at micron-scale were disclosed resulting in either kinetically three-dimensional (3D) interacting or non-percolating distribution. Corrosion protection performance of the hybrid coatings was examined whereas characteristics of the protection mechanism is substantially analysed from many perspectives, which all detailed in 2nd part of this study.

Solid, nanoporous silica-based spherical mesoporous MCM-41 and KIL-2 with interparticle mesoporosity as well as nanosized zeolite BEA materials differing in morphology and pore size distribution, were used as carriers for the preparation of resveratrol-loaded delivery systems. Two preparation methods have been applied: (i) loading by mixing of resveratrol and mesoporous carrier in solid state and (ii) deposition in ethanol solution. The parent and the resveratrol loaded carriers were characterized by XRD, TEM, N2 physisorption, thermal analysis, and FT-IR spectroscopy. The influence of the support structure on the adsorption capacity and the release kinetics of this poorly soluble compound were investigated. Our results indicated that the chosen nanoporous silica supports are suitable for stabilization of trans-resveratrol and reveal controlled release and ability to protect the supported compound against degradation regardless of loading method. The solid-state dry mixing appears very effective for preparation of drug formulations composed of poorly soluble compound. - Graphical abstract: trans-Resveratrol was stabilized in the pores of BEA zeolite, MCM-41and KIL2 mesoporous silicas. - Highlights: • BEA, KIL-2 and MCM-41 materials were used as carriers for resveratrol loading. • Resveratrol encapsulation in ethanol solution and solid state procedure were applied. • The solid-state preparation appears very effective formore » stabilization of trans-resveratrol.« less

Gelatinous polymer matrix microparticles containing silver nanoparticles (AgNPs) were prepared by a novel method to obtain quasi non-swelling anti-fouling paint additives with slow-release characteristics. A w/o type dispersion were elaborated with the aqueous phase of gelatin, urea, silver-nitrate and formaldehyde dispersed in linseed oil. Gelatin was cross-linked by formaldehyde, together with urea for limiting the swelling of the product. Silver-nitrate was reduced with the assistance of gelatin and formaldehyde into homogenously dispersed AgNPs. The microparticles and embedded AgNPs were visualized by scanning and transmission electronmicroscopy. Encapsulated AgNPs with ∼18 nm crystallite size were identified by X-ray powder diffraction. Characterization of gelatin–urea–formaldehyde polymer matrices was carried out by attenuated total reflectance FTIR spectroscopy. Silver dissolution from microparticles and paints with AgNP-containing microparticles was measured by inductively coupled plasma spectrometer and resulted in highly sustained release, compared to unmodified gelatin microparticles and paints containing uncapsulated silver salts. A 7-month-long fouling experiment run in natural sweetwater media showed that solvent-based acrylic paint with AgNPs-containing gelatinous microparticles as additives offered resistance against biofouling at low Ag-release ratio.

Innovative zinc-rich hybrid paint coatings were developed using nano-size particles composed of alumina hydrate modified with polystyrene-sulfonate (PSS) doped polypyrrole (PPy) and either purified or functionalised multi-walled carbon nanotubes (MWCNTs). General properties of the particles and their dispersions were characterised in 1st part of the work. Corrosion protection characteristics of the hybrids were examined on low-carbon steel panels by immersion and salt-spray chamber tests. Immersion tests were monitored by electrochemical impedance spectroscopy (EIS). Primers were analysed by glow-discharge optical emission spectroscopy (GD OES) and surface of the steel substrates was investigated by X-ray photoelectron (XPS) and FT-Raman spectroscopy. Improved barrier and galvanic function of the hybrids over traditional zinc-rich paints (ZRPs) were evidenced by performance metrics. Optimal protection characteristics were found when content of the particles was close to the statistical and kinetic percolation thresholds. Advanced protection mechanism of the hybrids is discussed on function of the nano-size filler benefiting the utilisation of sacrificial current output of the anodic zinc along with taking into account aspects of the multiple percolation theory. The interpretation given in this work is intended to facilitate design of next generation of corrosion protecting metal-rich coatings.

Silver sulfadiazine (AgSD) is the leading topical antibacterial agent for the treatment of burn wound infections. Antibacterial effect of AgSD is limited by its poor aqueous solubility, and antibacterial activity develops only by decomposition of AgSD to silver ions and sulfadiazine. In this study, it is for the first time that application of silver-modified nanoporous silica carriers (MCM-41 or SBA-15) loaded with sulfadiazine (SD), instead of silver sulfadiazine, overcoming the abovementioned disadvantages has been demonstrated. By direct or post synthesis methods, 5-15 nm sized silver nanoparticles can be stabilized in the channels or on the outer surface of nanoporous silica supports; moreover, the empty channels can be loaded by SD molecules. The SD-loaded, silver-modified materials show sustained release properties and similar or even better antimicrobial properties than AgSD. Adsorption of AgSD on nanoporous silica particles significantly improves its water solubility.

Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) combined with curve fitting procedures was used to characterize the poly(ethylene glycol) (PEG) layer of a pharmacologically relevant liposomal drug delivery system. The hydration of the polymer layer was described based on the ratio of the trans and gauche configurations of the C–O–C bond of the PEG molecules, which show a minimum at ∼6 mol% PEG-lipid molar ratio. The latter corresponds to highest bilayer stability, and coincides with the transition from the mushroom to the brush configuration of the PEG structure. This preliminary study showed that the ATR-FTIR technique is capable of qualitatively describing the hydration of the PEG-layer of stealth liposomes, which is in connection with the structure of the polymer on the liposomal surface.

Mesoporous silica material type SBA-15 was modified with different amounts of Zn (2 and 4wt.%) by incipient wetness impregnation method in ethanol. The parent, Zn-modified and quercetin loaded samples, were characterized by XRD, N2 physisorption, TEM, thermal gravimetric analysis, UV-vis and FT-IR spectroscopies and in vitro release of quercetin at pH5.5 which is typical of dermal formulations. By this loading method anhydrous quercetin was formed on the silica carrier It was found that the different hydrate forms of quercetin (dihydrate, monohydrate, anhydrite) significantly influence the physico-chemical properties of the delivery system. It was found that hydrate forms of quercetin can be differentiated by XRD and by FT-IR spectroscopic methods. Thus, by evaluating the interaction of the drug with the silica carrier the changes due to its hydration state always have to be taken into account. Formation of Zn-quercetin complex was evidenced on zinc modified SBA-15 silica by FT-IR spectroscopy. High quercetin loading capacity (over 40wt.%) could be achieved on the parent and Zn-containing SBA-15 samples. The in-vitro release process at pH=5.5 showed slower quercetin release from Zn-modified SBA-15 samples compared to the parent one. Additionally, the comparative cytotoxic experiments evidenced that quercetin encapsulated in Zn-modified silica carriers has superior antineoplastic potential against HUT-29 cells compared to free drug. Zn-modified SBA-15 silica particles could be promising carriers for dermal delivery of quercetin.

Utilization of various typesof multi-walled carbon nanotubes (MWCNTs) in zincrich paints (ZRPs) is presented addressing percolation and porosity related phenomena of traditional ZRPs. Hybrid paint coatings were formulated with 3.21wt% polypyrrole (PPy) deposited alumina-MWCNT inhibitor particles (PDAMIPs) and 70wt% zinc contents. Corrosion protection behavior of the hybrid coatings was investigated by electrochemical impedance spectroscopy (EIS), glow-discharge optical emission spectroscopy (GD OES), X-ray photoelectron spectroscopy (XPS), and FT-Raman spectroscopy. Immersion and salt-spray chamber tests gave evidence of improved galvanic protection and barrier nature of the hybrid coatings over the conventional ZRPs, whereas inhibited zinc corrosion and ignorable steel corrosion took place besides lower degradation of the binder. Zinc-rich hybrid paints with either high relative amount of polyelectrolyte-modified or low proportion of functionalized MWCNTsaffordedenhancedcorrosionprevention.Thisresultispartlyattributed to the nanotube volume fractions around the threshold of infinite cluster formation contributing to electrical percolation and galvanic action of the hybrids. Experimental results are discussed in a broader context on the basis of structure related findings of the PDAMIPs (described in Part I) and in the light of recent literature data. From the newly developed inhibitor particles, some of them are respected as worthy additives for application in hybrid coatings featuring high performance corrosion prevention functionality.

This paper is focused on studying corrosion protection of cold-rolled steel with alkyd paint coatings comprising nano-size alumina and either polystyrene-sulphonate (PSS) modified or sulphonated multi-walled carbon nanotube (MWCNT) supported polypyrrole (PPy). Single layer coatings (in thickness of 40 ± 5 μm) comprising PPy deposited alumina and PSS modified MWCNT supported PPy afforded viable protection during the 1 M sodium chloride test. The coatings containing PSS modified and weakly sulphonated MWCNTs (at volume fractions of 9.9 × 10−4 and 2.5 × 10−4) with PPy volume fractions of 3.5 × 10−3 and 2.5 × 10−3 provided effective corrosion prevention during the 1 M sodium chloride and hydrochloric acid solution tests. While inhibitor particles were characterised by infrared spectroscopy, corrosion products formed at the paint–steel interface were studied by X-ray photoelectron spectroscopy. Apart from the electron microscopy observations, rheology study of three-dimensional structure of the inhibitor particles was performed in dispersions at similar compositions to those used for the paint formulations. Thus, protection mechanism relating to both types of immersion tests is discussed in terms of properties of the inhibitor particles and their microstructure in the coatings.

This study unveils a chemical functionalization provoked phase transformation in the naphthalene modified multi-walled carbon nanotubes (MWCNTs) and the associated formation of amorphous carbonaceous particles of various size and morphology. Functionalized nanotubes were prepared by a sulfonation-oxidization and a highly corrosive oxidative sulfation reaction then characterized by means of thermogravimetry/mass spectrometry, X-ray photoelectron spectroscopy, scanning and transmission electron microscopy and Raman spectroscopy. In spite of the small change in the composition of sulfonation and sulfation reaction mixtures, conventional sulfonation with oleum resulted in lower sulfonation and higher oxidative conversion of MWCNTs accompanied with a mediated exohedral amorphization of the nanotubes, induced by the yield of sp 3 hybridization defect introduction. On the other hand, the newly applied oxidative sulfation reaction provided severe oxidative etching, cutting and shortening of MWCNTs with a subsequent high conversion of sulfate derivatisation of oxidized functionalities, which induced complete collapse and phase transformation of the nanotubes. Amorphization and phase transformation of oxidative sulfated MWCNTs have led to the formation of highly dispersed nano- and micron-size amorphous carbon spheres, rods and flake-like structures. Water based colloidal systems of excellent stability were prepared from the oxidative sulfated carbonaceous material. Consequently, the employed highly corrosive sulfation reaction is capable to provide highly functionalized carbonaceous nano and micro-size particles from MWCNTs.

FT-Raman spectra of human enamel surfaces from sound, affected (with 1 cavity) and highly affected (with at least 3 cavities) tooth samples were analyzed by principal component analysis (PCA). Major differences between the unaffected and affected tooth samples seem to arise from the structural changes along the c-axis of hydroxyapatite, the chief crystalline component of human dental enamel. Based on Fisher index calculations, the most discriminative value was obtained for the intensity of the only Raman active nu 2PO43- (E-1) symmetric deformation mode at 428 cm(-1). Moreover, these changes can be observed through the whole tooth enamel surface, establishing a predisposition to caries correlated to chemical and structural composition of tooth enamel. No spectral changes regarding the CO32- substitution were detected by both nondestructive FT-Raman and FTIR (Fourier transform infrared) spectroscopy of the powdered teeth samples. Copyright (C) 2009 John Wiley & Sons, Ltd.

In this chapter, corrosion protection performance of hybrid zinc-rich paints (ZRPs) formulated with zinc at 70 and 80 wt.%, and nano-size particulates at 3.21 and 1.75 wt.% contents is analyzed. The nano-size filler phase was composed of polypyrrole supported with either alumina or alumina/multiwalled carbon nanotubes. Durability of the coatings was tested with immersion and salt-spray chamber propagations. Protection mechanism of the hybrid ZRPs is discussed regarding structural and electrical properties of the particles and paint dispersions. Hybrid ZRPs indicate firm barrier nature, moderate inhibition, and restrained active galvanic function to steel substrates. Hindered mass transport and limited water uptake through the low porosity hybrid coatings combined with three-dimensional arrangement of nano-size particles at the statistical and kinetic percolation thresholds are key factors to provide well-balanced and highly efficient combined, complex protection to low carbon steel substrates. Nevertheless, incorporation of inhibitor particles results in completely different fundamental properties from those typical of traditional ZRPs.

This paper gives a short overview of the most popular vibrational spectroscopic methods used to study the structure of solids, surfaces and thin layers. Beside outlining the principle of measurements (transmission, various reflection methods, emission and Raman scattering), some examples are given illustrating the potentials of each technique.

The formation mechanism of ZrO2 — used for the stabilization of electrocatalytic thin films — from ZrOCl2·8H2O precursor was followed as the function of the firing temperature for the powder form as well as for the form of a thin film deposited on a titanium support. It was found that an intramolecular hydrolysis takes place upon heating, resulting in the liberation of hydrogen chloride. XRD, FT-IR and FT-Raman investigations revealed that polymorphism occurs in the oxide film. The upper surface of the film is of tetragonal structure, while the bulk is of cubic form stabilized by TiO2 formed by oxidation of the support.