Lilyana Pramatarova

• Bulgarian Academy of Sciences

Thin composite layers from polymer/nanoparticles (Ag-nanoparticles and detonation nanodiamonds) were prepared by plasma polymerization process on the base of hexamethyldisiloxane. The variation of the layer composition was achieved by changing the type of nanoparticles. The optical measurement techniques used were UV-VIS-NIR ellipsometry (SE), Four...

Abstract. Far field optical nanoscopy has been brought to the forefront with the 2014 Nobel Prize for chemistry in fluorescent nanoscopy for revealing intra-cellular details of tens of nm. In this review, we present an improved classification scheme that summarizes the many optical nanoscopy techniques that exist. We place particular emphasis on un...

The identification of biomaterials that support appropriate cellular attachment, proliferation, and functions is critical for tissue engineering and cell therapy. There is a growing interest in functional organic/inorganic composites where a small amount of nanometer-sized material yields better physicochemical properties for cells to attach, grow,...

The successful osseointegration of a bone implant is greatly dependent on its ability to support cellular adhesion and functions. Deposition of thin composite coatings onto the implant surface is a promising approach to improve interactions with cells without compromising implant bulk properties. In this work, we have developed composite coatings,...

Mesenchymal stem cells (MSCs) hold a great promise for use in many cell therapies and tissue engineering due to their remarkable potential to replicate indefinitely and differentiate into various cell types. Many efforts have been put to study the factors controlling stem cell differentiation. However, still little knowledge has been gained to what...

The combined unique properties offered by organic and inorganic constituents within a single material on a nanoscale level make nanocomposites attractive for the next generation of biocompatible materials. The composite materials of the detonation nanodiamond/polymer type possess spatial organization of components with new structural features and p...

Measuring surface roughness accurately at the micro and nano scale presents several challenges. While optical techniques can be used to rapidly measure large areas, significant variations can be found between results from different techniques on similar samples. In the present work, a comparison has been made between the results of two different sy...

Serratia sp. NCIMB 40259 is a non-pathogenic Gram-negative bacterium that is able to produce hydroxyapatite by a mechanism involving enzymic cleavage of organic phosphates. Serratia bacteria can attach and form a biofilm on glass, plastics, ceramics and metals and the method can be used to form three dimensional porous scaffolds and for coating 3D...

Recently, nanodiamonds (NDs) have attracted great interest due to their unique physical and chemical properties that could be used in various biological applications. However, depending on the origin, NDs often contain different impurities which may affect cellular functions and viability. Therefore, before their biomedical application, the cytotox...

BENDING ELASTICITY OF LIPID MEMBRANES IN THE PRESENCE OF NANODIAMOND PARTICLES IN THE AQUEOUS SOLUTION D. Haustov, T. Hikov, D. Mitev, I. Tsvetanov, L. Pramatarova, J. Genova Abstract: The present work aims to investigate the effect of detonation generated nanodiamond (DND) particles on elasticity of synthetic lipid membranes. Nanodiamonds have ex...

Cell morphology and organisation of actin cytoskeleton are closely related to all essential for cells processes including adhesion, growth and differentiation. Therefore, both cell characteristics can be used to assess the tissue compatibility of a biomaterial. Many approaches have been used to modify biomaterials surface in order to improve their...

Hydroxyapatite (HA) is the main component of human bones, a highly bioactive and biocompatible material; however, it has poor mechanical properties. Carbon-based coatings are found to significantly improve the mechanical properties of apatite, increase its adhesion, prevent metal ion release from metal implants and inhibit the formation of fibrous...

Composite layers of the detonation nanodiamond/polymer type possess a spatial organization of components with new structural features and physical properties, as well as complex functions due to the strong synergistic effects between the nanoparticles and polymer [1]. Composite layers were deposited by a plasma polymerization (PP) process of the de...

An important goal of materials science is the development of interfaces that integrate the functions of living cells and materials. Nature has given us plenty of ideas on how to build composites and organized structure (Heuer et al. 1992, Lowenstam, Weiner, 1989). The structure of a given biomaterial is crucial, when determining the cell response,...

New apatite (AP)/nanodiamond (ND) coating has been developed to improve physical and biological properties of stainless steel (SS) versus single AP coating. Homogeneously electrodeposited AP-ND layer demonstrates increased mechanical strength, interlayer cohesion and ductility. In the absence of serum, osteoblast-like MG63 cells attach well but poo...

Understanding the relationships between material surface properties, behaviour of adsorbed proteins and cellular responses is essential to design optimal material surfaces for tissue engineering. In this study we modify thin layers of plasma polymerized hexamethyldisiloxane (PPHMDS) by ammonia treatment in order to increase surface wettability and...

The present study reports on how detonation nanodiamond (DND) - plasma poly(hexamethyldisiloxane) composites (PPHMDS) affect osteoblast cell behavior. It has been established that various modified DND nanoparticles (Ag-DND and Si-DND) can be readily integrated into virtually all polymer matrices. In particular, PPHDMS composites have been developed...

Quantitative 3D characterisation of layer growth or modification in situ in liquid systems is a challenge because of the changing morphology of the layer and the presence of the growth liquid. Because of the limited bandwidth of many surface profiling techniques, measurement of microscopic surface roughness is generally limited to that of static su...

Biological apatite (AP) is the main component of human bones, and it is a highly bioactive and biocompatible inorganic material. However, it has insufficient mechanical parameters and adhesion to surfaces. Carbon‐based coatings, such as diamond‐like carbon, carbon nanotubes and amorphous carbon are found to significantly improve the mechanical prop...

Polycrystalline silicon (poly‐Si) layers were functionalized through the growth of biomimetic hydroxyapatite (HA) on their surface. HA is the mineral component of bones and teeth and thus possesses excellent bioactivity and biocompatibility. MG‐63 osteoblast‐like cells were cultured on both HA‐coated and un‐coated poly‐Si surfaces for 1, 3, 5 and...

In this work we study the ability of plasma polymer (PP) films obtained from hexamethyldisiloxane (HMDS) on silica glass (SG) to induce hydroxyapatite (HA)‐based composite layers from a mixture of simulated body fluid (SBF) and clear solution of detonation nanodiamond (DND) by a biomimetic process. The grown composites (PPHMDS/HADND) were studied b...

We studied the effect of the substrate chemistry on the morphology of hydroxyapatite‐detonational nanodiamond composite coatings grown by a biomimetic approach (immersion in a supersaturated simulated body fluid). When detonational nanodiamond particles were added to the solution, the morphology of the grown for 2 h composite particles was porous b...

International conference with proceedings Growth of calcium phosphate-nanodiamond composite on various solid surfaces, 7th International Conference of the Balkan Physical Union, Alexandroupolis, Greece, American Institute of Physics, September 2009 HAL Id : hal-00561642, version 1 ====================================================================...

Nanodiamond particles (ND, 4-6 nm in size) were added to a simulated body fluid (SBF) and electrodeposition (ED) at biological conditions (370C, pH 7.4) was performed on Ti surfaces. The novelty in this work was the addition of the ND particles to the SBF solution used as the electrolyte for the ED of biomimetic HA. The results from Fourier transfo...

Résumé/Abstract This study is designed to investigate the ability of plasma polymer films (PPHMDS), grown from the hexamethyldisiloxane (HMDS) monomer on stainless steel (SS) and silica glass (SG) substrates, to induce the deposition of composite layers from a mixture of saturated simulated body fluid (SBF) and detonation nanodiamond (DND) by a...

Thick transparent or semi-translucent layers are of growing importance in several key scientific and technological fields such as microelectronics, nanotechnology and biomaterials. New characterisation tools are required to cope with the complexity of these new materials and with the large range of scales involved (nm, μm, mm). In this paper, we re...

Metal materials have been used as implants, due to their excellent mechanical properties and corrosion resistance. However, in order to better bind to living bone they need an interfacial inorganic layer. Biological apatite is a bioactive and biocompatible inorganic material, and the main structural component of human bones. However, it has weak me...

This study was designed to investigate the suitability of the obtained composite as cell growth supports and to determine surface characteristic properties best suited to cells attachment and adhesion. The obtained new composite material is characterized by SEM, AFM, XPS and Contact angle measurements. Surface topography, chemical termination an...

Plasma polymerized hexamethyldisiloxane (PPHMDS) is a polymer frequently considered for biomedical application due to its easy fabrication, low cost and biocompatibility. However, a drawback of using PPHMDS in osteosubstitutive engineering is its high hydrophobicity, causing extremely low cellular interaction. Surface wettability can be altered i...

The flexible structure of polymers has enabled them to be useful in a wide variety of medical applications due to the possibility to tailor their properties to suit desired applications. For a long time, there has been an increasing interest in utilizing polymers as matrices for calcium phosphate-based composites with applications in hard tissue im...

Hydroxyapatite is a mineral widely studied as an artificial replacement material in dentistry and medicine due to its chemical and crystallographic resemblance to bone and tooth minerals. New trend of stimulating the hydroxyapatite formation in vitro has evolved by applying various sources of external energy. Lasers have been widely used in biomate...

After oxygen, silicon is the second most abundant element in the environment and is present as an impurity in most materials. The widespread occurrence of siliceous biominerals as structural elements in lower plants and animals suggests that Si plays a role in the production and maintenance of connective tissue in higher organisms. It has been show...

Hydroxyapatite/detonation nanodiamond composites are created on silica glass and cover glass by simple soaking process in an open deposition type set-up. The supersaturated solution (simulated body fluid, SBF) is prepared in a way to resemble the composition of human blood plasma. The composite growth is carried out through the addition of detonati...

Proteins are known to modulate the physical properties of minerals, and thus we anticipate that they will strongly influence the structure and the biological properties of biomimetically prepared carbonate-containing hydroxyapatite. This study was designed to learn more about the main morphological characteristics of hydroxyapatite layer grown on d...

Material surfaces play critical role in biology and medicine since most biological reactions occur on surfaces and interfaces. There are many examples showing that the surface properties of the materials control and are directly involved in biological reactions and processes in-vitro like blood compatibility, protein absorption, cell development, e...

The interest in stainless steel as a material widely used in medicine and dentistry has stimulated extensive studies on improving its bone-bonding properties. AISI 316 stainless steel is modified by a sequential ion implantation of Ca and P ions (the basic ions of hydroxyapatite), and by Ca and P implantation and subsequent thermal treatment in air...

Understanding the mechanisms of biomineralization continues to be an important area of research in physics, chemistry, materials science, medicine, and dentistry due to its importance in the formation of bones, teeth, cartilage, etc. Stimulated by these fascinating natural examples, as well as by certain others such as shells and corals, attempts a...

An increasing interest in biomimetics – design of materials based on natural biological structures-has led to the nanomechanical characterization of biomaterials. In this regard, nanoindentation has been used in conjunction with the determination of the mechanical properties of the extracellular matrix (ECM) proteins that are known as ligands in re...

One example for the medical application of nanodiamonds is their use in orthopedic implants. Detonation generated nanodiamonds (DND) are of great interest, because they are able to strengthen bone tissue, producing tougher and more flexible artificial bone implants. Carbon-based materials can be used to replace natural collagen in bone, in which th...

A calcium phosphate layer was grown on glass by a laser-liquid-solid interaction (LLSI) process in simulated body fluid (SBF). Glass samples with a layer grown by simple soaking in the SBF (i.e. without laser irradiation) were prepared for comparison. Formation of an inhomogeneous calcium phosphate (CaP) layer on both laser-treated and non-treated...

Calcium phosphate layers were grown on vacuum evaporated SiOx layers by using a biomimetic approach (from an aqueous solution that resembles the ion compositions and concentrations in human blood plasma). Micro-Raman and Fourier transform infrared spectroscopy showed that the grown layer was calcium phosphate. Coherence probe microscopy revealed th...

The use of Makyoh (magic-mirror) topography (MT), an optical surface characterisation tool, is demonstrated in the research of artificial biomineralisation. The method is based on the defocused detection of the whole-sample reflection of collimated light. The sample surface morphology is revealed in the form of dark/bright contrast regions in the r...

Biomineralization is intensively studied at present due to its importance in the formation of bones, teeth, cartilage, etc. Hydroxyapatite is one of the most common natural biomaterials and the primary structural component of bones and teeth. We have grown bio-like hydroxyapatite layers in-vitro on stainless steel, silicon and silica glass by using...

A time‐sparing method for the fabrication of structures organized on both the micro‐ and nanometer‐scale typical of nature is demonstrated by using a laser. In the applied laser‐liquid‐solid‐interaction method, a micrometer scale architecture with precisely controlled size and shape is created by laser irradiation of various surfaces, and nanostruc...

Recently nanostructured materials are receiving considerable attention for their possible applications as biomaterials. In this work three groups of samples have been prepared for testing their bioactivity (i.e. growth of calcium phosphate layers).

Organisms in nature create perfect fine structures, with remarkable properties, by interaction between inorganic and organic substances. Which one plays the primary role is unknown. There is a lack of information on the mechanism of this complex process, known as biomineralization. Under discussion are the chemistry of the nucleation points, supers...

The aim of this study was to find if nanocrystal layers obtained by well-established nanotechnology are able to induce deposition of hydroxyapatite [Ca10(PO4)6(OH)2]. It is known that nanosized objects and porous structures influence biological events and they may be used to create biologically integrated multifunctional devices including biomateri...

During the past several decades, hydroxyapatite (HA) has been used in many medical, orthopaedic, and dental applications. In this study, patterning by sequential implantation of Ca and P ion through a mask was used for selective surface modification of three classes of materials (stainless steel, silicon and silica glass). Some of the patterned sam...

Biological systems have a remarkable capability to produce perfect fine structures such as seashells, pearls, bones, teeth and corals. These structures are composites of interacting inorganic (calcium phosphate or carbonate minerals) and organic counterparts. It is difficult to say with certainty which part has the primary role. For example, the gr...

Opal is a natural nanostructure model. It possesses nanosized close packed silica spheres and a regular sublattice of voids, filled with molecular water and accessible for filling by other substances. Using natural opal as a substrate, no complimentary technique is needed to produce a patterned surface as it is present naturally. Thus, the possessi...

By application of a simple soaking process, ion beam-modified stainless steel, silicon and silica glass substrates are found to be able to induce hydroxyapatite (HA) (bone-and teeth-like mineral) on their surfaces after soaking for 3 days in a simulated body fluid. With the purpose to create micropatterned surfaces, the substrates are modified by s...

Thin films of high-quality polycrystalline silicon (poly Si) on different substrates are of interest for manufacturing thin film transistors, solar cells, and image sensors. In this study, we present the results of an investigation of poly Si films on glass, formed by nickel-induced crystallization. The process is based on isothermal annealing in a...

We present a study of simultaneous exposure of ion-implanted metal substrates to laser irradiation and solution. The proposed method for a growth of hydroxyapatite (HA, bone- and teeth-like material) employs a deposition system and a process, which allows interaction between a scanning laser beam and a liquid precursor solution (simulated body flui...

Porous silicon has been shown to be an excellent candidate biomaterial, following studies establishing its biostability and non-toxicity. These favorable properties, coupled with the ease of its topographical manipulation, make it a promising material for the growth of hydroxyapatite, which is used as an artificial bone material. In this paper, the...

A calcium phosphate layer was deposited on the surface of AISI 316 stainless steel by immersion in a solution, supersaturated for calcium and phosphorous ions. The substrates were pre-modified by ion implantation of Ca and P in order to induce nuclei for calcium phosphate growth on the surface. The reactivity of these surfaces towards crystal growt...

The study of biomineralization is inspiring new approach to the controlled fabrication of synthetic “biomimetic” materials such as nanostructured semiconductors [1, 2]. To prepare model surfaces on titanium substrates, two groups of samples: (i) SiOx:CdSe multilayers (MLs) and (ii) CdSe nanometer-sized crystals embedded in SiOx matrix, called compo...

Makyoh topography is applied to study the morphology of mechanically polished cross sections of renal stones. The results are compared to roughness and height profile data obtained by white-light interferometry, and to microstructure studies using optical and scanning electron microscopy. It is shown that Makyoh topography is able to furnish qualit...

This paper presents an experimental confirmation of the peculiar behaviour of coherent twin boundaries in sphalerite crystals through a “two step” experimental procedure involving free abrasive polishing for the “developing” of the stress pattern and infrared whole-sample optical reflection (“magic mirror”) for the registration. The results are in...

Surface properties and morphology of the mirror-like GaAs and GaSb substrate wafers for MBE and VPE growth were studied using whole sample optical reflection (“magic mirror”, or “Makyoh” phenomenon). Samples with various surface treatments were studied using this “Makyoh” method comparing the results with other methods such as X-ray diffractions, N...

Unintentionally doped GaAs molecular beam epitaxial layers were grown using MBE equipment developed for research purposes. The process of surface treatment of the GaAs substrates is described. The MBE grown layers were characterized using temperature dependent Hall effect measurements, and low temperature photoluminescence spectroscopy. The occurre...

The depth of the layer damaged by silicing of GaSb ingots has been determined by X-ray topography. The changes in the defect structure of substrates after successive etching to different depths by Br2/CH3OH and 1 HF:3 NNO3:1 CH3COOH have been studied. The effect of heat treatment carried out under conditions similar to the epitaxial process of subs...

This paper presents the results of the chemical and Liquid Phae (LP) Etching of the GaSb substrates. The method of anomalous transmission for X-ray topographic imaging of dislocations was used. It is shown that the dislocation density lowers with decreasing of the Sb content in the Ga melt at the LP-etching. [Russian Text Ignored]

This paper presents the results of LPE–growth of p(n)InAs1-ySby-n(p)GaSb(AlxGa1-xSb) heterostructures. It is shown the optimum technological regimes for growth of heterostructures p(n)InAs1-ySby-n(p)GaSb(AlxGa1-xSb) with a decreased lattice matching of the materials forming the heterojunction. [Russian Text Ignore]

This paper presents the results of investigation of the technological conditions of LPE growth of InAs1–ySby solid solutions on InAs substrates. It is shown that the chosen regions of composition of InAs1–ySby solid solutions and experimentally determined technological conditions allow the obtaining of InAs1–ySby solid solutions with lattice parame...

The present work shows the dependence of surface morphology of the GaSb and AlxGa1–xSb epitaxial layers on the conditions of LPE growth. It is found that for LPE growth at 500 °C a supersaturation of 5—10 °C and a cooling rate of 0.24—0.4°C/min for GaSb epitaxial layers and 0.8—1.2 °C/min for AlxGa1–xSb epitaxial layers is necessary to obtain a fla...

It is reported on the liquid phase epitaxial (LPE) growth of heterostructures on the base of InAs–AlxGa1–xSb. The paper includes the investigation of epitaxial layers of AlxGa1–xSb alloys on InAs substrates and results of experiments for the determination of optimum growth regimes. [Russian Text Ignored].

In the present work the possibility is demonstrated of growing gallium antimonide epitaxial layers on indium arsenide substrates using the liquid phase epitaxial (LPE) method. The influence is nivestigated of the growth conditions on the morphology of the surface and interface of the epitaxial structures InAsGaSb. The optimum technological regimes...