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Among key factors determining the fate of biomaterials in vivo are their interactions with blood serum proteins, which can lead to either successful integration or rejection/encapsulation. Although there are a number of studies investigating the interactions between proteins and bioimplants, comparable data for different types of biomaterials are lacking. To fill this gap, the adsorption kinetics and binding interactions of bovine serum albumin (BSA) with calcium phosphates (CaPs), namely hydroxyapatite (HA) and calcium deficient apatite (CaDHA), different TiO2 nanomaterials (TiNMs) presenting various morphologies such as nanoparticles (TiNPs), nanoplatelets (TiNPls), nanotubes (TiNTs) and nanowires (TiNWs), as well as their composites with CaDHA (CaDHA/TiNMs) were investigated. The kinetics of BSA adsorption on all studied materials was best described by pseudo-second order kinetics. The rate coefficient values obtained for the composites were lower than those for CaDHA and the corresponding TiNMs, while the adsorption density was higher for the composites than for CaDHA, except for the composites with TiNTs. Adsorption on TiNWs, CaDHA and all composites involved intraparticle diffusion, which was the rate- limiting step only for CaDHA/TiNTs. Fluorimetric titration experiments revealed that the number of binding sites was in larger than 1, except for TiNTs and TiNWs, indicating positive binding cooperativity. Interestingly, the values of the binding constants were lower for the TiNMs with a higher adsorption rate coefficient. Overall, BSA adsorption on the studied materials proved to be a complex process, which depended on the different surface properties of the adsorbents. Which property had a dominant role depended on the chemical identity of the adsorbent. The obtained comparable data for different types of materials point to the way of modifying their protein adsorption and binding properties.

Understanding the effect that specific amino acids (AA) exert on calcium phosphate (CaPs) formation is proposed as a way of providing deeper insight into CaPs’ biomineralization and enabling the design of tailored-made additives for the synthesis of functional materials. Despite a number of investigations, the role of specific AA is still unclear, mostly because markedly different experimental conditions have been employed in different studies. The aim of this paper was to compare the influence of different classes of amino acids, charged (aspartic acid, Asp and lysine, Lys), polar (asparagine, Asn and serine, Ser) and non-polar (phenylalanine, Phe) on CaPs formation and transformation in conditions similar to physiological conditions. The precipitation process was followed potentiometrically, while Fourier transform infrared spectroscopy, powder X-ray diffraction, electron paramagnetic spectroscopy (EPR), scanning and transmission electron microscopy were used for the characterization of precipitates. Except for Phe, all investigated AAs inhibited amorphous calcium phosphate (ACP) transformation, with Ser being the most efficient inhibitor. In all systems, ACP transformed in calcium-deficient hydroxyapatite (CaDHA). However, the size of crystalline domains was affected, as well as CaDHA morphology. In EPR spectra, the contribution of different radical species with different proportions in diverse surroundings, depending on the type of AA present, was observed. The obtained results are of interest for the preparation of functionalized CaPs’, as well as for the understanding of their formation in vivo.

Ova studija prikazuje mehanokemijsku sintezu kalcijeva oksalata u planetarnom kugličnom mlinu, bez prisutnosti i uz prisutnost otapala. Dosadašnja istraživanja uglavnom su bila usmjerena na otopinsku sintezu kalcijeva oksalata. U ovom radu opisujemo drugačiji pristup, koji će donijeti nova saznanja o sintezi kristala kalcijeva oksalata, koje su uzrokovane utjecajem mehaničke energije. Cilj istraživanja je sinteza, identifikacija i karakterizacija pojedine oksalatne hidratne faze sintetizirane iz kalcijevih soli (klorida, nitrata i sulfata). Ispitivan je utjecaj brzine mljevenja i praćena je reakcija u ovisnosti o vremenu sinteze. Strukturalna i termička svojstva uzoraka ispitana su spektroskopijom FTIR i termogravimetrijskom analizom (TGA). Morfološke karakteristike kalcijeva oksalata te raspodjela veličine čestica određene su optičkom mikroskopijom i dinamičkim raspršenjem svjetlosti (DLS). Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna., In this work, mechanochemical synthesis of calcium oxalate was done in a planetary ball mill, with and without addition of water as a solvent. Previous research was primarily focused on calcium oxalate synthesis in solution. Here we report a different approach which may contribute to new findings in calcium oxalate crystal synthesis caused by an influence of mechanical energy. The aim of this study was synthesis, identification, and characterization of particular oxalate hydrate phase synthesized with calcium salts (chloride, nitrate and sulphate). The effects of grinding speed and reaction duration regarding the time of synthesis were investigated. Structural and thermal sample properties were studied by FTIR spectroscopy and thermogravimetric analysis (TGA). Morphologic characteristics of calcium oxalate and size distribution were measured by optical microscopy and dynamic light scattering (DLS). This work is licensed under a Creative Commons Attribution 4.0 International License.

When a radiological and nuclear (R/N) emergency occurs, the categorization of individuals into those who are unaffected and those requiring medical intervention is a high priority. At times, a professional dosimeter is not available and therefore some common belongings may be used as fortuitous dosimeters. The preparation of these objects for the measurement should be such as to give the most accurate and precise results. This paper focused on the Photo-Stimulated Luminescence (PSL) response of salty crackers confronts the problem of sample preparation (mass, grain size), dose response and signal stability. The dose response was determined for doses up to 5 Gy, which allowed the calculation of the limit of detection. Additionally, the signal stability was investigated for samples irradiated with 0.3 and 3 Gy. The observed decrease of the signal does not prevent the detection in the dose range typical for R/N emergency. The main dosimetric characteristics were investigated by using two different models of PSL readers equipped with single (infrared) or double (infrared, blue light) stimulation. The results indicated that the limit of detection can be improved by applying blue light stimulation. Moreover, strong correlation of the measurements performed in the two different instruments, as well as the rapidity of the analysis and the simplicity of the operations, suggest that this method can be suitable for a rapid radiation triage of a large number of civilians in a mass casualty event. The study was simultaneously conducted by two laboratories (Ruder Bošković Institute, RBI, Croatia and Istituto Superiore di Sanità, ISS, Italy) involved in the BioPhyMeTRE project (grant No. G5684) supported by NATO Science for Peace and Security Programme.

Hydroxyapatite (HA, Ca10(PO4)6(OH)2), a calcium orthophosphate, due to its similarity to the inorganic part of human’s hard tissue, is among the most frequently used hard tissue regeneration biomaterial [1]. As such, the effects of HA ageing in media similar to blood plasma need to be studied, specifically after sterilization with γ-radiation, to better understand the possible structural changes it would undergo in the human body. Moreover, such changes in ion substituted HAs are particularly interesting since so called biological HA is in fact non-stoichiometric poorly crystalline, calcium deficient, Na-, Mg- and carbonate substituted HA (Dorozhkin, 2012) [2]. In this study, HA and 3 different substituted HAs were irradiated to 25 kGy with Co-60 γ-rays and their electron paramagnetic (EPR) spectra were recorded 1, 14 and 28 days after treatment with saline solution and simulated body fluid (SBF) [3]. The ion substituted HAs were doped with Mg and Si: 2% Mg; 2% Mg + 0.4% Si and 2% Mg + 1.25% Si. EPR spectra were analysed, and the most pronounced peaks assigned. The effects of ageing in the two media are presented and discussed. IX International Conference on Radiation in Various Fields of Research : RAD 2021 : book of abstracts; June 14-18, 2021; Herceg Novi, Montenegro

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.

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.

Selenium nanoparticles (SeNPs) were first designed as nutritional supplements, but they are attractive also for use in diagnostic and therapeutic systems owing to their biocompatibility and protective effects. This study aimed to examine if different SeNPs stabilization strategies affect their (i) antimicrobial activity against bacteria Escherichia coli and Staphylococcus aureus and yeast Saccharomyces cerevisiae and (ii) toxicity to human cells of different biological barriers i.e., skin, oral and intestinal mucosa. For surface stabilization, polyvinylpyrrolidone (PVP), poly-L-lysine (PLL) and polyacrylic acid (PAA) were used rendering neutral, positively and negatively charged SeNPs, respectively. The SeNPs (primary size ~80 nm) showed toxic effects in human cells in vitro and in bacteria S. aureus, but not in E. coli and yeast S. cerevisiae. Toxicity of SeNPs (24 h IC50) ranged from 1.4 to >100 mg Se/L, depending on surface functionalization (PLL > PAA > PVP) and was not caused by ionic Se. At subtoxic concentrations, all SeNPs were taken up by all human cell types, induced oxidative stress response and demonstrated genotoxicity. As the safety profile of SeNPs was dependent not only on target cells (mammalian cells, bacteria, yeast), but also on surface functionalization, these aspects should be considered during development of novel SeNPs-based biomedical products.

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.

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.

This paper aims to evaluate the effects of a product containing colloidal silver in the aquatic environment, using duckweed Lemna gibba as a model plant. Therefore, growth parameters, photosynthetic pigments content and protein content as physiological indices were evaluated. Changes in the content of non-enzymatic antioxidants and activity of several antioxidant enzymes, alongside with the accumulation of hydrogen peroxide and lipid peroxidation end- products were assessed to explore the potential of colloidal silver to induce oxidative stress. The commercially available colloidal silver product contained a primary soluble form of silver. The treatment with colloidal silver resulted in significant physiological and biochemical changes in L. gibba plants and a consequent reduction of growth. Accumulation of silver caused altered nutrient balance in the plants as well as a significant decrease in photosynthetic pigments content and protein concentration. The antioxidative response of L. gibba plants to treatment with colloidal silver was inadequate to protect the plants from oxidative stress caused by metal accumulation. Silver caused concentration- dependent and time- dependent hydrogen peroxide accumulation as well as the elevation of lipid peroxidation levels in L. gibba plants. The use of commercially available products containing colloidal silver, and consequent accumulation of silver, both ionic and nanoparticle form in the environment, represents a potential source of toxicity to primary producers in the aquatic ecosystem.

The synthesis and characterization of new materials together with the investigation of their physical properties represent areas of the greatest interest in chemistry today. Our knowledge about controlling the way in which metal-complexes, ligands and counter-ions assemble into more complex structures is rising every day. Even though each new discovery about the very intriguing and sometimes ambiguous relationship between a chemical structure of single molecules and non-covalent interactions that might govern their formation into higher-order structures is a one step closer to the successful design of new materials with desired properties. Moreover, even the simplest variations in chemical structure like exchange of hydrogen bond donors and acceptors, halide counter-ions may influence propensity toward specific hydrogen bond patterns. Followed by the same idea, we have examined newly synthesized cadmium-based complexes linked to polymeric chains capable of acting as robust supramolecular synthons, yet enough flexible to accommodate to slight variations in molecular structure. Transformed pyridine-based ligands have at least two functionalities – they are able to complexate metals and form intermolecular interactions depending on substituents of aromatic ring. Therefore, they have already been well documented in literature as plausible building blocks and a logical joint between solely organic- and solely inorganic-based three-dimensional architectures. This research work utilizes an experimental and theoretical approach in order to gain new insights about the supramolecular behavior of cadmium halide complexes with pyridine-based ligands functionalized in positions three and four with an oxime group. We report a synthesis of ligands and the derived complexes including description of crystallization techniques, spectral characterization, and determination of thermal properties. A computational study help us in further analysis of intermolecular interactions important for assembly of molecules in three-dimensional networks and to rationalize whether a dimeric supramolecular motif labeled as R22(6) according to graph-set theory prevails over R22(8), or vice versa.