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Magnetic cellulose (MC) is prepared by hydrolysis of iron precursors in an aqueous dispersion of cellulose nanofibres. A thin, flexible film was then prepared by removing the water and drying the sample in a hot press at 110°C followed by the removal of the water. Structural analysis of MC was performed and correlated with the measurement of electromagnetic properties. The magnetic cellulose showed high magnetic saturation of 68 emu/g with characteristic superparamagnetic behaviour, and conductivity in a range of semiconductors, with an increase of DC conductivity with increasing temperature. Modification of cellulose with Fe3O4 has a positive effect on the DC conductivity and lower limit that needs to be exceeded to achieve a stable and sustainable conductivity in the range of ~5-20 ×10-9 (Ω cm)-1 @30 °C is 65 wt% of the Fe3O4 for studied MC composites. The surface roughness of the magnetic cellulose shows a dynamic change with increasing temperature, which is closely related to the enhancement of MC conductivity. A theoretical model of the conductivity is calculated based on continuous 2D percolation and shows an interesting agreement with the experimental results.

Morphological, rheological, and thermal properties of biopolymeric microcapsules loaded with novel plant growth regulators (2, 3-dehydroaspartic acid dimethyl ester (PGR1), Z-isomer of the potassium salt of 2-amino-3-methoxycarbonylacrylic acid (PGR2) and 1-methyl-3-methylamino-maleimide (PGR3)) were studied. Microcapsule formulations containing PGR2 or PGR3 had a granular surface structure with substructures, whereas those containing PGR1 had smooth surfaces with no grain substructures. All formulations had storage moduli (G ′) greater than loss moduli (G ′ ′), indicating viscoelastic solid behavior. The application of angular frequency over the range tested did not signifcantly change G’ and G’’ values indicating well-ordered structures for all samples. Compared to other formulations, the highest values of storage modulus, yield strength and fow point obtained for formulations with PGR3 indicated an advantage in terms of stability in various physical environments. Thermal analysis showed good thermal stability of all formulations and is consistent with rheological properties confrming well-ordered structures. Encapsulated PGRs afect the intensity of intermolecular forces (electrostatic interaction and hydrogen bonds), thus changing the crosslinking density of the alginate network and the basic physicochemical properties of the formulations.

The influence of small inorganic cations (Na+ ions in this case) on the core@shell silica nanoparticles, formed by the room temperature hydrolysis of TEOS in aqueous TPAOH (subsequent addition of NaOH – SA) and NaOH/TPAOH (direct addition of NaOH – DA) solutions was investigated by DLS, AFM, pH measurements, 29Si-NMR and 23Na-NMR. The obtained results showed that the smaller Na+ ions, displace parts of the larger TPA+ ions from the shells of the core@shell primary silica nanoparticles (PNPs), by the exchange process. This causes exposition of TPA-free terminal –OH and –O- groups to the solution and thus, enables the binding of the collided nanoparticles by the Si-O-Si bonds (aggregation). The PNPs in the aggregates, formed above the critical aggregation concentration (CAC) of silicate species are separated by the “bulky” shell (TPA-polysilicate anions) that prevents the close contacts between the nanoparticles cores and thus, their coalescence. When Na+ ions are present during the formation of the nanoparticles, a part of the Na+ ions is incorporated to the nanoparticle core. Remove of the TPA+ ions from the shells of the nanoparticles, formed below the CAC, enables close contacts of the nanoparticles cores and thus, their coalescences inside the aggregates. These findings show that the selective removal of the TPA+ ions from the nanoparticle shell enables the control of the composition and size of the precursor species and thus, represent a good basis for the engineering of nanosized (alumino)silicate microporous and mesoporous materials.

Oxidative stress (OS) induced by the disturbed homeostasis of metal ions is one of the pivotal factors contributing to neurodegeneration. The aim of the present study was to investigate the effects of flavonoid myricetin on copper-induced toxicity in neuroblastoma SH-SY5Y cells. As determined by the MTT method, trypan blue exclusion assay and measurement of ATP production, myricetin heightened the toxic effects of copper and exacerbated cell death. It also increased copper-induced generation of reactive oxygen species, indicating the prooxidative nature of its action. Furthermore, myricetin provoked chromatin condensation and loss of membrane integrity without caspase-3 activation, suggesting the activation of both caspase-independent programmed cell death and necrosis. At the protein level, myricetin-induced upregulation of PARP-1 and decreased expression of Bcl-2, whereas copper-induced changes in the expression of p53, p73, Bax and NME1 were not further affected by myricetin. Inhibitors of ERK1/2 and JNK kinases, protein kinase A and L-type calcium channels exacerbated the toxic effects of myricetin, indicating the involvement of intracellular signaling pathways in cell death. We also employed atomic force microscopy (AFM) to evaluate the morphological and mechanical properties of SH-SY5Y cells at the nanoscale. Consistent with the cellular and molecular methods, this biophysical approach also revealed a myricetin-induced increase in cell surface roughness and reduced elasticity. Taken together, we demonstrated the adverse effects of myricetin, pointing out that caution is required when considering powerful antioxidants for adjuvant therapy in copper-related neurodegeneration.

Rogoznica Lake (RL) is an eutrophic and affected by climate change marine lake on the eastern Adriatic coast (43°32’N, 15°58’E). During the year the lake is strongly stratified into oxic and anoxic layers. Due to intense sulfate reduction, anoxic bottom layer is enriched in dissolved HS- (up to 5 mM). At the oxia-anoxia boundary, a pinkish colored chemocline (up to 50 cm) develops seasonally, and it is characterized by a dense population of purple phototrophic sulfur bacteria (PSB) [1]. PSB are known to store sulfur S(0) intracellularly, which by cell lysis would be released in water, and under euxinic conditions solubilized by HS- in nucleophilic polysulfides, SX2-. SX2-can play an important role in metal, carbon and sulfur cycles. In this work, for the first time, differential pulse voltammetry (DPV) was used for direct determination of SX2- in euxinic marine environment (RL), where total RSS (mainly HS-) varied between 0.1 and 3 mM. Concentration of SX2-, as well as total RSS, varied seasonally depending on the chemocline position, light intensity and HS- concentration. During stratification in summer, when PSB reached maximum abundance, the presence of SX2- was determined in the highest concentrations (up to 0.1 mM S(0)). Maximum was found approx. 1 m bellow the chemocline, where due to sinking of lysed PSB cells, maximum concentration of biologcally S(0) would be expected. Presence of S(0) granules in the cells and their release into water upon cell lysses, induced in laboratory conditions by acidification of the studied sample, was confirmed by AFM. The acidification as a standard methodological step in electroanalytical determination of volatile and nonvolatile RSS (RSSNV) [2] are now proved to overestimate RSSNV for 30-50% in samples enriched in PSB. Results from this study clearly prove the SX2- presence in the anoxic water of RL and shed light on a crutial role of the PSB in their formation and dynamics. [1] M. Čanković, J. Žučko, I. Dupčić Radić, I. Janeković, I.Petrić, I. Ciglenečki, G.Collins, Syst Appl Microbiol, 2019. [2] E. Bura-Nakić, G.R. Helz, I. Ciglenečki, B. Ćosović, Geochim Cosmochim Acta, 2009.

Continuing our previous research work on a drug delivery system based on combined AC/DC magnetic fields, we have developed a prototype AC/DC magnetic syringe device for stimulation of drug release from drug carriers, with the options of injecting/removing drug carriers. The porous Fe3O4 carrier, in a dose-dependent manner, causes acute oxidative damage and reduces the viability of differentiated SH-SY5Y human neuroblastoma cells, indicating the necessity for its removal once it reaches the therapeutic concentration at the target tissue. The working mechanism of the device consists of three simple steps. First, direct injection of the drug adsorbed on the surface of a carrier via a needle inserted into the targeted area. The second step is stimulation of drug release using a combination of AC magnetic field (a coil magnetised needle with AC current) and permanent magnets (DC magnetic lens outside of the body), and the third step is removal of the drug carriers from the injected area after the completion of drug release by magnetising the tip of the needle with DC current. Removing the drug carriers allows us to avoid possible acute and long term side effects of the drug carriers in the patient's body, as well as any potential response of the body to the drug carriers.

Iron nanoparticles are used as a targeted drug delivery system. The nanocarrier itself can be genotoxic, trigger oxidative stress or cell death. Therefore, we developed an AC/DC magnetic syringe for injecting, stimulating drug release and safe removing of the nanocarrier. Alongside we optimized the method for nanoparticles’ drug release kinetics and testing cytotoxicity in vitro.•This paper presents detailed instructions for construction of AC/DC magnetic syringe device for stimulated drug release, injection and ejection of magnetic nanoparticles; nanoparticles preparation; adsorbing methylene blue on nanoparticles; determination of drug release kinetics from nanocarriers on the example of methylene blue•Gomori´s Prussian blue reaction for differentiated SH-SY5Y human neuroblastoma cell line; MTT viability assay optimized for differentiated SH-SY5Y human neuroblastoma cell line and antioxidant enzymes activities assay and lipid peroxidation methods are optimized for cell analyses cell cultivation for nanoparticles cytotoxicity testing in vitro.•Those protocols are the first step toward further testing the effect of nanoparticles in vivo, on brain tissue., Graphical abstract Image, graphical abstract

The constantly growing need for advanced bone regeneration materials has motivated the development of calcium phosphates (CaPs) composites with a different metal or metal-oxide nanomaterials and their economical and environmentally friendly production. Here, two procedures for the synthesis of CaPs composites with TiO2 nanoplates (TiNPl) and nanowires (TiNWs) were tested, with the immersion of TiO2 nanomaterials (TiNMs) in corrected simulated body fluid (c-SBF) and precipitation of CaP in the presence of TiNMs. The materials obtained were analyzed by powder X-ray diffraction, spectroscopic and microscopic techniques, Brunauer–Emmett–Teller surface area analysis, thermogravimetric analysis, dynamic and electrophoretic light scattering, and their hemocompatibility and ability to induce reactive oxygen species were evaluated. After 28 days of immersion in c-SBF, no significant CaP coating was formed on TiNMs. However, the composites with calcium-deficient apatite (CaDHA) were obtained after one hour in the spontaneous precipitation system. In the absence of TiNMs, CaDHA was also formed, indicating that control of the CaP phase formed can be accomplished by fine-tuning conditions in the precipitation system. Although the morphology and size of crystalline domains of CaDHA obtained on the different nanomaterials differed, no significant difference was detected in their local structure. Composites showed low reactive oxygen species (ROS) production and did not induce hemolysis. The results obtained indicate that precipitation is a suitable and fast method for the preparation of CaPs/TiNMs nanocomposites which shows great potential for biomedical applications.

Neurodegenerative diseases are one of the leading causes of disability and death worldwide. Intracellular transduction pathways that end in the activation of specific transcription factors are highly implicated in the onset and progression of pathological changes related to neurodegeneration, of which those related to oxidative stress (OS) and neuroinflammation are particularly important. Here, we provide a brief overview of the key concepts related to OS- and neuroinflammation-mediated neuropathological changes in neurodegeneration, together with the role of transcription factors nuclear factor erythroid 2–related factor 2 (Nrf2) and nuclear factor-κB (NF-κB). This review is focused on the transcription factor p53 that coordinates the cellular response to diverse genotoxic stimuli, determining neuronal death or survival. As current pharmacological options in the treatment of neurodegenerative disease are only symptomatic, many research efforts are aimed at uncovering efficient disease-modifying agents. Natural polyphenolic compounds demonstrate powerful anti-oxidative, anti-inflammatory and anti-apoptotic effects, partially acting as modulators of signaling pathways. Herein, we review the current understanding of the therapeutic potential and limitations of flavonols in neuroprotection, with emphasis on their anti-oxidative, anti-inflammatory and anti-apoptotic effects along the Nrf2, NF-κB and p53 pathways. A better understanding of cellular and molecular mechanisms of their action may pave the way toward new treatments.

The structural integrity, elasticity, and fluidity of lipid membranes are critical for cellular activities such as communication between cells, exocytosis, and endocytosis. Unsaturated lipids, the main components of biological membranes, are particularly susceptible to the oxidative attack of reactive oxygen species. The peroxidation of unsaturated lipids, in our case 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), induces the structural reorganization of the membrane. We have employed a multi-technique approach to analyze typical properties of lipid bilayers, i.e., roughness, thickness, elasticity, and fluidity. We compared the alteration of the membrane properties upon initiated lipid peroxidation and examined the ability of flavonols, namely quercetin (QUE), myricetin (MCE), and myricitrin (MCI) at different molar fractions, to inhibit this change. Using Mass Spectrometry (MS) and Fourier Transform Infrared Spectroscopy (FTIR), we identified various carbonyl products and examined the extent of the reaction. From Atomic Force Microscopy (AFM), Force Spectroscopy (FS), Small Angle X-Ray Scattering (SAXS), and Electron Paramagnetic Resonance (EPR) experiments, we concluded that the membranes with inserted flavonols exhibit resistance against the structural changes induced by the oxidative attack, which is a finding with multiple biological implications. Our approach reveals the interplay between the flavonol molecular structure and the crucial membrane properties under oxidative attack and provides insight into the pathophysiology of cellular oxidative injury.

Detailed vibrational assignments for twelve flavonoids (seven flavones (flavone, 3- and 5-hydroxyflavone, chrysin, apigenin, fisetin and luteolin) and five flavonols (galangin, kaempferol, quercetin, morin and myricetin)) have been made based on own and reported experimental data and calculations at the B3LYP/6-31 + G(d,p) level of theory. All the molecules are treated in a uniform way by using the same set of redundancy-free set of internal coordinates. A generalized harmonic mode mixing is used to corroborate the vibrational characteristics of this important class of molecules. Each flavonoid molecule can be treated from the vibrational point of view as made of relatively weakly coupled chromone and phenyl part. It has been shown that the strongest band around 1600 cm− 1 need not be attributable to the C O stretching. The way the vibrations of any of the hydroxyl groups are mixed with ring vibrations and vibrations of other neighboring hydroxyl groups is rather involved. This imposes severe limitations on any attempt to describe normal modes of a flavonol in terms of hydroxyl or carbonyl group vibrations. The role of water molecules in the appearance of flavonoid IR spectra is emphasized. Knowing for the great affinity of phosphate groups in lipids towards water, the immediate consequence is a reasonable assumption that flavonoid lipid interactions is mediated by water.

Superparamagnetic magnetite nanoparticles (MNPs) with excellent biocompatibility and negligible toxicity were prepared by solvothermal method and stabilized by widely used and biocompatible polymer poly(ethylene glycol) PEG-4000 Da. The unique properties of the synthesized MNPs enable them to host the unstable and water-insoluble quercetin as well as deliver and localize quercetin directly to the desired site. The chemical and physical properties were validated by X-ray powder diffraction (XRPD), field emission scanning electron microscopy (FE–SEM), atomic force microscopy (AFM), superconducting quantum interference device (SQUID) magnetometer, FTIR spectroscopy and dynamic light scattering (DLS). The kinetics of in vitro quercetin release from MNPs followed by UV/VIS spectroscopy was controlled by employing combined stationary and alternating magnetic fields. The obtained results have shown an increased response of quercetin from superparamagnetic MNPs under a lower stationary magnetic field and s higher frequency of alternating magnetic field. The achieved findings suggested that we designed promising targeted quercetin delivery with fine-tuning drug release from magnetic MNPs.

Flavonoids, polyphenols with anti-oxidative activity have high potential as novel therapeutics for neurodegenerative disease, but their applicability is rendered by their poor water solubility and chemical instability under physiological conditions. In this study, this is overcome by delivering flavonoids to model cell membranes (unsaturated DOPC) using prepared and characterized biodegradable mesoporous silica nanoparticles, MSNs. Quercetin, myricetin and myricitrin have been investigated in order to determine the relationship between flavonoid structure and protective activity towards oxidative stress, i.e., lipid peroxidation induced by the addition of hydrogen peroxide and/or Cu2+ ions. Among investigated flavonoids, quercetin showed the most enhanced and prolonged protective anti-oxidative activity. The nanomechanical (Young modulus) measurement of the MSNs treated DOPC membranes during lipid peroxidation confirmed attenuated membrane damage. By applying a combination of experimental techniques (atomic force microscopy&mdash, AFM, force spectroscopy, electrophoretic light scattering&mdash, ES and dynamic light scattering&mdash, DLS), this work generated detailed knowledge about the effects of flavonoid loaded MSNs on the elasticity of model membranes, especially under oxidative stress conditions. Results from this study will pave the way towards the development of innovative and improved markers for oxidative stress-associated neurological disorders. In addition, the obtained could be extended to designing effective delivery systems of other high potential bioactive molecules with an aim to improve human health in general.

The structure-property relationship in alginate microparticles (microspheres and microcapsules prepared with or without Trichoderma viride spores (Tv) was investigated. Surface morphology, structure and release behavior from alginate microparticles strongly depend on calcium concentration and presence of Tv and chitosan layer. All microparticles exhibited a granular surface structure with substructures consisting of abundant smaller particles. In vitro active agents release study revealed that the increase in calcium cation concentration reduced the release rate of Tv (~84% for microspheres ; ~57% for microcapsules) and calcium cations (~20% for microspheres ; ~23% for microcapsules). The average decrease in k values due to chitosan layer addition is 41% for Tv and 93% for calcium ions, respectively. The underlying Tv release mechanism from microspheres is anomalous transport kinetics, whereas from microcapsules is controlled by Type II transport. The differences in microparticle surface properties did not affect the mechanism controlling calcium ions release detected as diffusion through microparticles.

A new copper complex, trans-diaqua-trans-bis [1-hydroxy-1,2-di (methoxycarbonyl) ethenato] copper (abbreviation Cu(II) complex), was synthesized and its plant growth regulation properties were investigated. The results show a sharp dependence of growth regulation activity of the Cu(II) complex on the type of culture and its concentration. New plant growth regulator accelerated the development of the corn root system (the increase in both length and weight) but showed a smaller effect on the development of the wheat and barley root systems. Stimulation of corn growth decreased with increasing Cu(II) complex concentration from 0.0001% to 0.01% (inhibition at high concentrations—0.01%). The development of corn stems was also accelerated but to a lesser extent. Chitosan-coated calcium alginate microcapsules suitable for delivery of Cu(II) complex to plants were prepared and characterized. Analysis of the FTIR spectrum showed that complex molecular interactions between functional groups of microcapsule constituents include mainly electrostatic interactions and hydrogen bonds. Microcapsules surface exhibits a soft granular surface structure with substructures consisting of abundant smaller particles with reduced surface roughness. Release profile analysis showed Fickian diffusion is the rate-controlling mechanism of Cu(II) complex releasing. The obtained results give new insights into the complexity of the interaction between the Cu(II) complex and microcapsule formulation constituents, which can be of great help in accelerating product development for the application in agriculture

In this study, the influence of physio-chemical properties of four printing substrates, fibrous papers (filter, bulky, recycled), and polymer film (synthetic paper) on the size of the thermochromic (TC) prints microcapsules was investigated. Results indicate that interaction between thermochromic ink and printing substrate determine the print morphology, i.e., porosity and roughness of printing substrate affect dimensions of TC microcapsules of resulting prints, while ink adhesion affects dimensional changes during heating&ndash, cooling cycle. Atomic force microscopy (AFM) analysis showed that microcapsules of the prints, on the surface of the smoothest synthetic paper, possess the smallest diameter and height, while, on the most porous and the most roughened surface of F paper, the microcapsules of the prints possess the highest diameter and height. By increasing the temperature to 40 &deg, C, the biggest changes in the shape of the microcapsules (increase in height and decrease in diameter) were obtained using the surface of the hydrophilic filter paper. While using the recycled paper surface, the situation is opposite, the height and diameter of the microcapsules are reduced, and the microcapsules penetrate deeper into the paper structure (due to optimum adhesion). On the bulky paper surfaces, which are more hydrophobic than recycled paper (higher interfacial tension), the increase of temperature does not cause any significant changes in the shape and position of the microcapsules. The same behavior is observed using hydrophobic non-porous synthetic paper.

Supported lipid layers are commonly used as model systems for biological membranes with high potential for diverse (bio)technological applications including the development of novel sensors. The aim of this study was to investigate the influence of mixing ratio and subphase used in the monolayer assembly on the surface free energy (SFE) of supported palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and oleic acid triglyceride (triolein) (TO) mixed lipid monolayers on a mica substrate. The supported layers were formed by Langmuir–Blodgett transfer of mixed monolayers assembled on a subphase of ultra-pure water and electrolyte (0.55 M NaCl, pH 8.1). AFM and fractal/lacunarity analysis were used to elucidate their relevant topographical features while the SFE and its polar and dispersive component were determined using contact angle measurements. The results showed that the monolayers formed on an electrolyte subphase are more stable than those on a water subphase, while their homogeneity and topographical features depend on the mixing ratio. The SFE of a mixed layer depends on the mixing ratio and the subphase type used in the self-assembly of the Langmuir monolayer, but is also influenced by the saturation/unsaturation of the hydrophobic tail chain. Thus, changing the subphase and the POPC/TO mixing ratio allows for change of the supported layer's wetting properties from hydrophilic to strongly hydrophobic. The results of this study should contribute to better understanding of the SFE of supported mixed lipid films and allow the tailoring of surfaces with targeted properties.

Self-assembly of organic molecules onto metallic surfaces is an efficient way to modify surface properties of metallic materials. The aim of this paper was to examine the possibility of improving the corrosion stability of copper nickel alloy in chloride environment by self-assembled films of palmitic and stearic acid. Electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to determine the protective properties of the fatty acids films. Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and contact angle (CA)measurements were used to evaluate structural properties of the surface layers. It was found that even a small difference in a fatty acid chain length might have a strong effect on layer stability in aqueous medium.

Self-assembled mono- and multilayers of stearic acid have been examined as corrosion protection systems for copper-nickel alloy in 3% sodium chloride solution. We found that self-assembled multilayers of stearic acid provide more efficient and durable corrosion protection to copper- nickel alloy than just a single monolayer. Electrochemical techniques, such as potentiodynamic polarization and electrochemical impedance spectroscopy, were used to determine the protective properties of the stearic acids films. Sum frequency generation spectroscopy, atomic force microscopy, contact angle measurements and ellipsometry were used to evaluate structural properties and thickness of the surface layers. It was found that the increase of corrosion protection from mono- to multilayer films depends on the number of layers that are formed but also on their homogeneity.

Calcium phosphates (CaPs) composites with different TiO2 nanomaterials (TiNMs) have recently attracted attention due to their potential application as implant materials for hard tissue regeneration. Among different synthetic routes for such composites, biomimetic synthesis attracts special attention as a green synthesis route. To rationalize biomimetic synthesis, the influence of surface structure and surface charge density of different TiNMs on CaPs precipitation should be determined. In this paper, for the first time, the influence of TiO2 nanoparticles (TiNPs) and titanate nanotubes (TiNTs) on CaPs spontaneous precipitation was investigated. In addition, the ability of TiNMs to induce CaPs formation in corrected simulated body fluid (c-SBF) was tested. The advancement of the CaPs precipitation was followed by potentiometric measurements, while the obtained materials were characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy (RS), powder X-ray diffraction (PXRD), scanning (SEM) and transmission (TEM) electron microscopy, electron paramagnetic resonance spectroscopy (EPR), Brunauer-Emmett-Teller surface area analysis (BET), dynamic (DLS) and electrophoretic light scattering (ELS), atomic force microscopy (AFM) and thermogravimetric (TGA) analysis. Both TiNMs showed poor ability to promote CaPs formation in c-SBF which can be attributed to their low absolute zeta-potential value. However, during spontaneous precipitation, they exhibited uncommon dual influence on precipitation kinetics, i.e. inhibition of initially formed amorphous calcium phosphate (ACP) transformation at lower and promotion at higher concentrations. After one hour of reaction time, in the presence of both TiNMs, calcium deficient hydroxyapatite was formed (CaDHA). Morphology of the CaDHA depended on the type and concentration of TiNMs. However, PXRD, EPR and TGA characterization confirmed that there is no significant difference between CaDHA formed in the presence of different TiNMs, which indicates that CaDHA composites with different TiNMs could be prepared at similar conditions. In addition, they can be prepared in a much shorter time compared to the usual procedure with SBF. Obtained results confirm the importance of surface structure and charge in CaPs – TiNMs interactions. They as well contribute to a deeper insight into precipitation processes on the nanosurfaces, which enables a rational approach not only in the biomimetic synthesis of novel biocomposites for hard tissue regeneration but also of composites for other applications.

Chitin, a bioactive, antibacterial and biodegradable polymer is commonly utilized by diverse marine organisms as the main scaffold material during biomineralization. Due to its properties, chitin is also of interest as a component of organo-inorganic composites for diverse biomedical applications. In this study, chitinous fibers isolated from the cuttlebone of the common cuttlefish (Sepia officinalis, L.) are characterized and evaluated for use as an integral part of mineralized hydrogels for biomedical applications. Since marine organisms use calcium carbonates (CaCO3), while vertebrates use calcium phosphates (CaP) as the main inorganic hard tissue components, and both minerals are used in hard tissue engineering, they were compared to determine which composite is potentially a better biomaterial. Hydrogel mineralization was conducted by subsequent dipping into cationic and anionic reactant solutions, resulting in the formation of a CaCO3 or CaP coating that penetrated into the hydrogel. Obtained composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM), rheology, swelling tests and simple compression. The results indicate that β-chitin can be used for the preparation of moldable hydrogels that are easily mineralized. Mineralized hydrogels have higher elasticity than non- mineralized ones while swelling is better if the extent of mineralization is lower. Further optimization of the hydrogels composition could improve their stress response and Young’s modulus, where the current hydrogel with a higher extent of CaP mineralization excels in comparison to all other investigated composites.

Following the assumption that the crucial processes governing the formation, properties and evolution of the core(amorphous silica)@shell(organocations) nanoparticles take place during short-time, room-temperature (rt) stirring/aging of the homogeneous reaction mixtures (HmRMs) formed by hydrolysis of TEOS (tetraethyl orthosilicate) in solutions of Org(OH)n, we investigated these processes by various experimental methods (pH, ionic conductivity, 29Si-NMR, dynamic light scattering and atomic force microscopy). The analysis of the data obtained by detail and careful investigation of the "model" HmRMs having the starting chemical composition: xTEOS:0.25TPAOH:20H2O (TPAOH = tetrapropylammonium hydroxide; x = 0.05 – 1), offer some new elements for the understanding of the mechanisms of formation and rt evolution of the core@shell silica nanoparticles: (1) There is a resolute evidence of the formation of the stable, about 1.2 nm sized core(amorphous SiO2)@shell(TPA+ ions) nanoparticles below the critical aggregation concentration (CAC). (2) Due to the intensive particulate processes (growth, aggregation, disaggregation, dissolution) which take place during the rt aging of the investigated HmRMs, the equilibrated core@shell silica nanoparticles do not exist as individual primary ones, but as the aggregates (about 2 nm to about 20 nm), composed of 1 – 2 nm sized "primary" nanoparticles. (3) In spite of the most frequent meaning that the nanoparticle shell is composed of the "free" TPA+ ions adsorbed on the surface of the nanoparticle core, the results of this study show that the nanoparticle shell can be formed mainly by attachment of the polysilicate anions (silicate oligomers), associated with TPA+ ions, on the surfaces of the nanoparticles cores.

The investigation of liquid crystal (LC) mixtures is of great interest in tailoring material properties for specific applications. The recent discovery of the twist-bend nematic phase (NTB) has sparked great interest in the scientific community, not only from a fundamental viewpoint, but also due to its potential for innovative applications. Here we report on the unexpected phase behaviour of a binary mixture of twist-bend nematogens. A binary phase diagram for mixtures of imino-linked cyanobiphenyl (CBI) dimer and imino-linked benzoyloxy-benzylidene (BB) dimer shows two distinct domains. While mixtures containing less than 35 mol % of BB possess a wide temperature range twist-bend nematic phase, the mixtures containing 55–80 mol % of BB exhibit a smectic phase despite that both pure compounds display a Iso–N–NTB–Cr phase sequence. The phase diagram shows that the addition of BB of up to 30 mol % significantly extends the temperature range of the NTB phase, maintaining the temperature range of the nematic phase. The periodicity, obtained by atomic force microscopy (AFM) imaging, is in the range of 6–7 nm. The induction of the smectic phase in the mixtures containing 55–80 mol % of BB was confirmed using polarising optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction. The origin of the intercalated smectic phase was unravelled by combined spectroscopic and computational methods and can be traced to conformational disorder of the terminal chains. These results show the importance of understanding the phase behaviour of binary mixtures, not only in targeting a wide temperature range but also in controlling the self-organizing processes.

Oxidative stress has been recognised as an important pathological mechanism underlying the development of neurodegenerative diseases. The biomarkers for assessing the degree of oxidative stress have been attracting much interest because of their potential clinical relevance in understanding the cellular effects of free radicals and evaluation of the efficacy of drug treatment. Here, an interdisciplinary approach using atomic force microscopy (AFM) and cellular and biological molecular methods were used to investigate oxidative damage in P19 neurons and to reveal the underlying mechanism of protective action of quercetin. Biological methods demonstrated the oxidative damage of P19 neurons and showed that quercetin improved neuronal survival by preventing H2O2- induced p53 and Bcl-2 down-regulation and modulated Akt and ERK1/2 signalling pathways. For the first time, AFM was employed to evaluate morphologically (roughness, height, Feret dimension) and nanomechanical (elasticity) properties in H2O2-induced neuronal damage. The AFM analysis revealed that quercetin suppressed H2O2-provoked changes in cell membrane elasticity and morphological properties, thus confirming its neuroprotective activity. The obtained results indicate the potential of AFM-measured parameters as a biophysical markers of oxidative stress-induced neurodegeneration. In general, our study suggests that AFM can be used as a highly valuable tool in other biomedical applications aimed at screening and monitoring of drug- induced effects at cellular level.

Nano-delivery systems and the use of nanoparticles (NPs) both for diagnostic and therapeutic purposes are among the most active research fields today. Therapeutically interesting compounds are flavonoids due to the multitude of their actions, such as anti- inflammatory, antibacterial, antioxidant etc., in all kinds of cells and tissues [1]. The difficulty that must be circumvented is the poor flavonoid solubility in water. The necessity to locally increase the flavonoid concentration could be realized by means of flavonoid encapsulation or adsorption into/onto nanocarriers. Lipids, a class of amphiphilic molecules capable of forming bilayers, provide a membrane scaffold for hosting proteins and other molecules that controls matter exchange between the cell and its surrounding. Lipid bilayers can be therefore used as simplified model systems to study various properties of the membranes, in particular their interactions with different molecular species [2]. The present project is aimed to ensure the necessary prerequisite for future studies of the inhibition of lipid peroxidation of liposomes and supported lipid bilayers (SLBs) by free and encapsulated flavonoids. The investigation of interactions of structurally different flavonoids with two and/or three component lipid membranes using atomic force microscopy (AFM) [3], attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) [4] and fluorescence microspectroscopy (FMS) [5] will ensure the explanation of the correlation between structural properties of flavonoids, either free or encapsulated, and structural changes in model membranes made of unsaturated phosphatidylcholine/cholesterol lipid mixtures. The obtained information of the studied system at molecular level acquired by spectroscopic techniques in combination with the nano-scale structural picture gained by AFM would much contribute to more complete understanding of the NP-membrane interactions References 1. M. JazvinšćakJembrek, L. Vuković, J. Puhović, J. Erhardt, N, Oršolić, J MolNeurosci 47 (2012) 286–299. 2. S. Šegota, D. Vojta, G. Pletikapić, G. Baranović, Chem. Phys. Lipids, 186 (2015) 17–29. 3. S. Šegota, D. Vojta, D. Kendziora, I. Ahmed, Lj. Fruk, G. Baranović, J. Phys. Chem. B 119 (2015) 5208–5219 4. Z. Arsov, L. Quaroni, Biochem. Biophys.Acta 1778 (2008) 880–889. 5. I. Urbančič, A.Ljubetič, Z. Arsov, J. Štrancar, Biophys. J. 105(2013) 919–927.

The films consisting of gold nanoparticles, prepared by electron beam evaporation on glass substrates, exhibit interesting optical properties due to localized surface plasmon resonance. The tailoring of optical properties has been achieved by varying deposition mass thickness and substrate temperature. The relation between optical and structural properties has been studied. Optical characterization of samples has been carried out by variable angle spectroscopic ellipsometry and for structural characterization grazing incidence small angle X-ray scattering and atomic force microscopy have been used. Results show how the structural properties, obtained by using specific fabrication parameters, influence the resulting optical characteristics. The differences in concentration, shape and size of the produced gold nanoparticles result in a spectral shift of localized surface plasmon resonance, and a change of its width and intensity. The appearance of percolation is signed by Drude-like infrared absorption.

The influence of monomeric and micellar concentrations of the cationic monomeric, dodecyltrimethylammonium bromide (DTAB), and the corresponding dimeric, bis(N, N-dimethyl-N-dodecyl) ethylene-1,2-diammonium dibromide (12-2-12), surfactants on the formation and transformation of amorphous calcium phosphate (ACP) was investigated. The combination of microscopy (AFM and TEM) and light scattering techniques (size and zeta potential measurements) enabled, for the first time, the simultaneous monitoring of the effect that additives exert on different length scales during CaP formation in solution - from prenucleation clusters and ACP particles to the crystalline phase. Depending on their aggregation state (monomers or micelles) and the geometry of the aggregate (spherical or elongated micelles), DTAB and 12-2-12 have exhibited different effects on the rate of ACP transformation, as well as on the morphology of the amorphous and crystalline phases. It was shown that the effect of surfactants on the precipitation process observed on the microscale could be a result of different pathways on the nanoscale. The obtained results may have implications for the understanding of the general mechanism of inorganic-organic interactions underlying the biomineralization processes, as well as for materials science.

This review highlights relevant issues about applications and improvements of atomic force microscopy (AFM) toward a better understanding of neurodegenerative changes at the molecular level with the hope of contributing to the development of effective therapeutic strategies for neurodegenerative illnesses. The basic principles of AFM are briefly discussed in terms of evaluation of experimental data, including the newest PeakForce Quantitative Nanomechanical Mapping (QNM) and the evaluation of Young’s modulus as the crucial elasticity parameter. AFM topography, revealed in imaging mode, can be used to monitor changes in live neurons over time, representing a valuable tool for high-resolution detection and monitoring of neuronal morphology. The mechanical properties of living cells can be quantified by force spectroscopy as well as by new AFM. A variety of applications are described, and their relevance for specific research areas discussed. In addition, imaging as well as non-imaging modes can provide specific information, not only about the structural and mechanical properties of neuronal membranes, but also on the cytoplasm, cell nucleus, and particularly cytoskeletal components. Moreover, new AFM is able to provide detailed insight into physical structure and biochemical interactions in both physiological and pathophysiological conditions.

Nanostructured sol-gel TiO2 films were prepared on a glass substrate by means of the dip-coating technique with titanium tetraisopropoxide as a precursor. TiO2 sols were synthesized with and without the addition of polyethylene glycol (PEG) as a structure-directing agent. The synthesized sol-gel TiO2 were characterized by XRD, AFM, FTIR and Micro-Raman spectroscopy. The photocatalytic activity of the films was evaluated by the photocatalytic degradation of Lissamine Green B (LGB) dye (dissolved in water) as a model pollutant with the predominant irradiation wavelengths of 365 nm (UV-A). It was found that the addition of PEG to the initial sol affects the surface morphology and the photocatalytic properties of prepared sol-gel TiO2 films. AFM analysis confirmed the presence of nanostructured sol-gel titania films on the glass substrate. Roughness parameters (Ra, Rq, and Zmax) of the sol-gel TiO2 film with the addition of PEG are higher than the parameters of the sol-gel TiO2 film without the addition of PEG. The TiO2 film prepared with the addition of PEG has a higher surface density (a larger active surface area) and a better photocatalytic activity in the degradation of the LGB dye solution than the TiO2 film prepared without the addition of PEG.

Oxidative stress has been recognised as an important pathological mechanism underlying the development of neurodegenerative diseases. The biomarkers for assessing the degree of oxidative stress have been attracting much interest because of their potential clinical relevance in understanding the cellular effects of free radicals and evaluation of the efficacy of drug treatment. Here, an interdisciplinary approach using atomic force microscopy (AFM) and cellular and biological molecular methods were used to investigate oxidative damage in P19 neurons and to reveal the underlying mechanism of protective action of quercetin. Biological methods demonstrated the oxidative damage of P19 neurons and showed that quercetin improved neuronal survival by preventing H2O2-induced p53 and Bcl-2 down-regulation and modulated Akt and ERK1/2 signalling pathways. For the first time, AFM was employed to evaluate morphologically (roughness, height, Feret dimension) and nanomechanical (elasticity) properties in H2O2-induced neuronal damage. The AFM analysis revealed that quercetin suppressed H2O2-provoked changes in cell membrane elasticity and morphological properties, thus confirming its neuroprotective activity. The obtained results indicate the potential of AFM-measured parameters as a biophysical markers of oxidative stress-induced neurodegeneration. In general, our study suggests that AFM can be used as a highly valuable tool in other biomedical applications aimed at screening and monitoring of drug-induced effects at cellular level.

One-layer, two-layer and three-layer titania films on AISI 304 stainless steel were deposited by sol-gel process and dip-coating method. Two sols were prepared by using titanium isopropoxide as a precursor, propanol as a solvent, nitric acid as a catalyst and acetylacetone for peptization. Both of the prepared sols contained the same amount of mentioned components, the only difference was in the addition of polyethylene glycol (PEG) as templating reagent to one of the sols. After calcination at 550°C, deposited films on the stainless steel substrate were characterized by atomic force microscope (AFM). Influence of layer number as well as addition of polyethylene glycol on morphology of titania films was analysed and discussed. Generally, by increasing the number of layers and by addition of polyethylene glycol, roughness parameters increase by changing surface topography. The surface topography analysis is very important when choosing the adequate industrial application of prepared layers.