Hydrothermal synthesis of hematite (Fe2O3) nanoparticles, structure, morphology and magnetic properties

У овој докторској дисертацији описана је хидротермална синтеза наночестичног хематита (α-Fe2O3), као и карактеризација материјала, у сврху његове потенцијалне примене у различитим областима. Синтетисани узорци су карактерисани ренгеноструктурном анализом (XRDP), електронском микроскопијом (SEM и TEM), магнетометријом са вибрирајућим узорком (VSM) и вибрационом спектроскопијом (FTIR и Raman). Извршена је и математичка анализа морфологија честица, применом дескриптора облика на одабране ТЕМ слике узорака...This doctoral dissertation presented hydrothermal synthesis and characterization of hematite (α-Fe2O3) nanoparticles, towards potential applications in differrent fields. Synthesized sample were characterized with X-ray powder diffraction method (XRDP). electrone microscopy (SEM and TEM), vibrating sample magnetometry (VSM) and vibrational spectroscopy methods (FTIR and Raman). Mathematical analysis of nanoparticle morphology was also conducted, applying shape descriptors on segmented TEM sample images..

Фотодиелектрична карактеризација светлосног погона Au/TiO2 наномотори у течном медију

This article reports on photodielectric properties of hydrocolloids of TiO2 particles and Au/TiO2 hybrid particles of lateral dimension of ∼200 nm. Illumination of the colloids with visible light did not cause measurable changes in their electrical conductivity, while the application of UV (365 nm) light led to photoinduced increase in conductivity of up to 2%. The photogeneration of ions in water, regardless of the presence of the particles, makes a dominant contribution to the photoinduced increase in conductivity of the colloid

The calcification of collagen by HAP functionalized carbon materials

Bone is composed of two phases. The organic phase is made of collagen fibrils assembled in broad fibers acting as a template for mineralization. The mineral phase comprises hydroxyapatite (HAP) crystals grown between and inside the collagen fibers. We have developed a material using functionalized carbon nanotubes, carbon fibers and glasy carbon as scaffold to initiate in vitro mineralization. Mentioned carbon materials are functionalized with carboxylic groups prior to decorating. All samples were dispersed in ultra-pure water and incubated for 2 weeks in a synthetic body fluid with dispersed HAP, in order to induce the calcification of the functionalized carbon materials. Atomic force microscopy (AFM) and transmision electron microscopy (TEM) showed that Ca2+ and PO4 3- ions were deposited as round-shaped nodules. Raman spectroscopic studies confirmed the HAP formation, and image analysis made on TEM pictures showed that HAP were packed around and inside the carbon materials together. All three types of investigated carbon materials leading to successful calcification of collagen. This suggests that it takes the presence of carbon materials to prevent it from calcification of collagen, independent of the structures of the material

Anthocyanin-functionalized biopolymer films as pH-sensitive indicators

Anthocyanins are water-soluble, non-toxic flavonoid pigments, which produce the blue, red and purple color of many plants. Color change of anthocyanin extracts is a direct consequence of the transformation of their chemical structure when exposed to different pH conditions. Optical properties investigated in UV-Vis absorption and PL spectra show a clear difference between anthocyanins in acidic and in alkaline environments. Chitosan, a natural-based, non-toxic and biodegradable polysaccharide, is chosen as an ideal matrix for nanocomposites. It is proven to be a good carrier for anthocyanins, because of its ability to entrap the indicator dyes and at the same time the ability to release anthocyanins when in contact with an acidic environment. In this research, we have developed anthocyanin-enhanced biopolymer indicator systems, which provide fast colorimetric response to alterations in pH levels of the environment. Transmittance spectra of nanocomposites show excellent light-blocking properties of the films. This opens up possibilities for advancement in future technology of smart biodegradable food packaging biomaterials. The availability of innovative and healthy materials reduces the need for using synthetic plastic in the modern food industry.IX International School and Conference on Photonics : PHOTONICA2023 : book of abstracts; August 28 - September 1, 2023; Belgrad

MALDI TOF Mass Spectrometry Characterization of Collagen

Collagen is the most frequently occuring fibrillar protein in mammals, which can be found in cartilage, tendon, bone, ligament, skin, etc. The structure of collagen is based on a complicated helix structure of single chains of amino acids (most abundant is glicine-Gly, proline-Pro and hydroxyproline-Hyp) which are connected by hydrogen bonds. We tried to establish MALDI method to get better resolution of collagen’s mass spectra. Digested collagen (type II from bovine Achilles tendon which was digested with collagenase from Clostridium histolycium) has been analysed on MALDI-TOF MS in order to find peptide’s fragments that are characteristic for collagen. In mass spetra we found peaks of peptides, which is highly indicative for collagen (GlyPro-Hyp, Gly-Pro-Asp, Gly-Pro-Glu ect.) We hope that it should be possible to obtain MS analysis and structure characterization of collagen by MALDI-TOF/TOF in future

Fabrication Hybrid Janus Nanoparticles and Their Application as Light-Driven Micromotors

Interest in developing micro/nano motors (MNMs) increased rapidly in the last couple of years. These advanced systems can address critical challenges in manipulation of objects at small-scales. Micro/nano motors are capable to move controllably in fluids under the influence of various stimuli (thermal, magnetic, light, etc.) and perform specific operations, including propelling micromachines. Here we synthesized two types of hybrid Janus particles, Au-TiO2 and AgAg2S-TiO2, and tested them as possible light-driven micromotors. Light, as a versatile power source, allows non-invasive control of the motion of the motors with high spatial and temporal resolutions. Illumination induce asymmetric reactions on the two sides of the Janus particles, which can create the propulsion. To optimize the properties of the MNMs, we performed synchrotron radiation gas-phase photoemission spectroscopy (SR PES) of the free standing hybrid particles at synchrotron SOLEIL, France. SR PES provided an information about the valence level alignment of the components, possible hybrid states and dominant scattering processes.SCMP : the 21st symposium on condensed matter physics : book of abstracts; 26-30 June 2023, Belgrad

Collagen Structure and Morphology Analysis by TEM and AFM

Collagens, one of the most abundant on the Earth, are family of proteins which constitute the basis of connective tissue (extracellular matrix) in multicellular organisms. We used collagen type II from bovine Achilles tendon. In further work, collagen has been studied by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Using TEM we successfully obtained images of collagen and whole collagen fibrils. Using AFM we captured images of whole collagen as well as images of fragments from collagenase-treated collagen (it was digested with collagenase from Clostridium histolycium). AFM images of collagenase-treated collagen showed many fibrils grouping into large bundles – collagen fiber. Based on obtained images we studied surface morphology, shape and length of fragments from collagenase-treated collagen

MALDI TOF and AFM studies of DNA/SWNT hybrids

A primer is a strand of nucleic acid that serves as a starting point for DNA synthesis. DNA, as a large molecule, is very difficult for analysis by means of mass spectrometry. However, primer, as a short sequence of nucleic acid, is much more convinient for e.g. MALDI TOF MS analysis. Mass spectrometric experiment resulted in quality MALDI TOF spectra of 3 primers. Compound 3-HPA (3- hydroxypicolinic acid) showed the best results as matrix. AFM studies were also conducted, for both pure primer samples and hybrids of primer molecule with single wall carbon nanotubes (SWNT). Thus, obtained functionalisation of SWNT with DNA primers was confirmed by AFM imaging. AFM images clearly showed wrapping of DNA structures around nanotube „template“. Functionalisation of SWNT is very important for potential applications of nanotubes in biomedical field. MALDI TOF mass spectrometry, in combination with AFM imaging, proved its great potential in analysis of short DNA sequences, and indicated the possibility of investigating more complex DNA structures.Physical chemistry 2012 : 11th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 201

Mass spectrometric investigation of silver clusters

Silver clusters were produced by two different synthesis procedures, related with different reduction species. PVA (polyvinyl alcohol) was successfully utilized as a source to reduce silver (Ag) metal ions without using any additional reducing agents to obtain Ag clusters. Silver clusters with atoms numbering 5-29 are registered through mass spectrometry using MALDI TOF and MALDI TOF/TOF techniques. Analysis showed that clusters with magic numbers are the largest, while those with an odd number of atoms are larger than clusters with an even number of atoms. Stability of these molecules, magic number actually, is in relation with their electronic configuration

Pellets from long-eared owls (asio otus) as indicators of soil quality

Pellets from Long-Eared Owls (Asio otus) were collected from four localities in the city and in the vicinity of Belgrade. The element content in the pellets was analyzed. The results indicate that owl pellets may be useful for monitoring environmental conditions, specifically soil quality