List of Abstracts 2021: SESSION C - BIONANOTECHNOLOGY, NANOMATERIALS IN MEDICINE
Date: October 20, 2021
In modern-day medicine, nanotechnology and nanoparticles are used for the diagnosis, prevention, and treatment of disease and to gain a better understanding of underlying human disease mechanisms. There are many different types of nanomaterials are used in medicine, each of which can be modified in a infinite number of ways. It would therefore be overwhelming to attempt to create a comprehensive description of all the materials that could potentially be used in nanomedicine. It is worth mentioning many reviews and articles about quantum dots (QD) as very attractive and prospects materials for research of biomedical tasks. In this review, we will try to generelize and discuss the present accomplishments and prospects in the utility and applications of QD in nanomedicine. We will summarize general and particular requirements for use QD in medicine (surface passivation, adsorption, functionalization, bioconjugation, uptake or incorporation of QD by living cells etc.), using of QDots as imaging agent of ions, single molecules, cellular structures and receptors, individual cells and tissue along with targeting, tracking, distribution etc., properties of QDs as multimodality imaging probes, multifunctionality QD as good candidates for theranostic platforms (the combination of a QD imaging agent with a therapeutic agent, the use of QD in studying drug release, QDs as sensitizers for photodynamic therapy, use of luminescent QD to initiate biological functions etc.), using of QD as part of sensors without function of imaging agent. In addition, main concerns about the potential toxicity of QDs are also introduced.
The digital polymerase chain reaction (dPCR) rising in development and popularity. dPCR is a suitable solution for the analysis of rare samples or samples available only in small quantities. The determination of absolute copy number of target DNA without the use of external standards together with the possibility of statistical analysis due to the binary nature of the data are the main advantages of dPCR. Chip dPCR compared with droplet dPCR is less widely used and developed. The precision and dynamic range of dPCR is dependent on the number of reaction wells. The increment of the number of reaction wells on chip, leads to the issue of appropriate method of sample loading. Our designed and fabricated silicon chips with 26 448 microwells with the volume of one microwell 59 pL was tested for suitable method of sampling for our experimental dPCR technology. During incorrect sample loading on chip surface, it arises to the amplification defects e.g. evaporation of sample, cluster formation, uneven fluorescence intensity or unfilled wells which led to incorrect amplification and subsequent quantification. We verified couple of sampling methods to improve the loading efficiency and precision of quantification. Our optimized method of sample loading for our dPCR technology was developed. The dPCR chip was filled with the 4 µL of PCR master mix, covered with 10 µL of mineral oil and the modified covered glass.
Theranostics is a new field of medicine, which combines specific diagnostic and therapeutic methods. It is based on the use of nanoparticles, e.g. iron oxide nanoparticles, which can be divided based on size, shape, type of core, shell, etc [1]. Nanoparticles (NPs) in the blood might reach and accumulate in the kidneys potentially leading to disruption of whole body homeostasis and therefore it is important to know their nephrotoxicity [2].
We investigated the effect of two types of iron oxide nanoparticles with the same core (7.6 nm) coated with either polyethylene glycol (PEG) or bovine serum albumin (BSA) on specific renal glomerular cells - podocytes.
Both types of nanoparticles triggered different effects on cells, although they were of the same material and the same size of the core. PEG-coated NPs were approx. five times more toxic than BSA-coated NPs. Inflammation has also been observed. mRNA expression of proinflammatory factors was detected 5-hour after treatment of PEG coated iron oxide nanoparticles, but not after treatment with BSA-coated NPs. The opposite effect was observed after a 24-hour exposure when only BSA-coated nanoparticles increased the expression level of pro-inflammatory factors. We observed the different impact of both types of NPs on podocytes also in other experiments.
Our results show that the coating of nanoparticles is as important for the resulting functional nanoparticle as other variables, if not more. A full understanding of nano:bio interactions in a living system, especially in excretion organs like kidneys will be needed for successful implementation of nanoparticles in the treatment of diseases.
ACKNOWLEDGEMENTS: This work was supported by the Slovak Research and Development Agency under the contract No. APVV-16-0579
This study was performed during the implementation of the project Buildingup Centre for advanced materials application of the Slovak Academy of Sciences, ITMS project code 313021T081 supported by Research & Innovation Operational Programme funded by the ERDF.
REFERENCES: [1] Xie J, Lee S, Chen X. Nanoparticle-based theranostic agents. Adv Drug Deliv Rev. 2010;62(11):1064-1079. doi:10.1016/j.addr.2010.07.009.; [2] Rana SVS (2021) Recent Advances on Renal Toxicity of Engineered Nanoparticles-A Review. J Toxicol Risk Assess 7:036. doi.org/10.23937/2572-4061.1510036.
The biocompatible nanosuspension of CuS nanoparticles using bovine serum albumin (BSA) was prepared using a two-stage mechanochemical approach. CuS nanoparticles were firstly synthetized by a planetary ball milling (according to [1]) and then a wet stirred media milling in a solution of BSA was introduced to yield the CuS-BSA. The nanosuspension was stable for more than 9 months, as confirmed by photon cross-correlation spectroscopy and zeta potential measurements. The obtained nanosuspension was characterized by UV-Vis and PL spectroscopy.The fluorescent properties of the nanocrystals were confirmed by PL spectroscopy, which showed that tryptophan could be closer to the binding site than the tyrosine residue. Scanning and transmission electron microscopy confirmed the nancocrystalline character of CuS and the presence of BSA. The biological activity was determined by in vitro tests on selected cancer and healthy human cell lines. The results have shown that CuS-BSA nanosuspension inhibits the metabolic activity of the cells as well as decreases their viability upon photothermal ablation.
ACKNOWLEDGEMENTS: This work was supported by the Slovak Agency for Research and Development on the basis of contract no. APVV-18-0357 and by the Scientific Grant Agency of the Ministry of Education, Science, Research and Sport (project no. 2/0044/18).
ZnO is becoming one of the most important semiconductors in biological applications because of its specific properties such as low cost, large direct bandgap (3.37 eV), and great biocompatibility. Interactions between ZnO and different proteins have garnered significant attention due to the growing implementation of ZnO-based materials for biomedical and pharmaceutical purposes. Amongst all proteins, great attention has been paid to ZnO biointerfaces with serum albumin (SA) as the most abundant protein in blood plasma. To date, multiple studies investigated the interactions between ZnO and bovine serum albumin (BSA) experimentally (Chakraborti et al. 2012). Even though the previous research in this field provided valuable information on ZnO-BSA interfaces, it is still unclear how the BSA adsorbs and binds on ZnO surfaces.
In this work, we finally conduct a comprehensive, systematic study on the details of adsorption of BSA on various ZnO surfaces by atomic force microscopy and nanoshaving measurements corroborated by force field (FF) and density functional based tight-binding (DFTB) calculations. AFM measurements and FF calculations are in good agreement, showing higher roughness and thickness of adsorbed BSA layers on the polar (0001 ̅ ) surface. Nanoshaving experiments suggest stronger binding of BSA molecules to the (101 ̅0) plane compared to other surfaces. This is correlated with DFTB calculations for BSA amino acid residues indicating the energetically more stable complexes on the (101 ̅0) surface. We also show that interaction between these specific AAs and ZnO surfaces controls charge transfer and HOMO-LUMO energy positions in the BSA-ZnO complexes. The results thus provide valuable information for elucidating many data reported in the literature as well as for diverse applications of ZnO.
Cyclodextrins (CDs) belong to the group of cyclic oligosaccharides. They commonly contain 6, 7 or 8 glucopyranose units arranged in a bucket shape. Thanks to the hydrophobic inner cavity, they are capable of forming inclusion complexes with various hydrophobic molecules.
To achieve better manipulation or greater versatility of use, CDs are applied as a part of larger structure, including polymers. Cyclodextrin nanosponges represent cyclodextrins highly crosslinked in the polymeric structure. Thanks to the crosslinking, it is possible to incorporate in the nanosponge not only hydrophobic but also hydrophilic molecules. The complexation ability and easy tunability of the material made nanosponges very promising in a number of applications, including biomedical, pharmaceutical, and environmental applications.
Highly discussed is the potential use of cyclodextrin nanosponges in drug delivery. Moreover, appropriate functionalization may give them the ability to target specific receptors and facilitate the cell penetration in the treated tissue.
The synthesis of mannosylated β-cyclodextrin nanosponges is presented. After full characterization and deep examination of cytotoxicity and drug loading capacity, the material might be used in targeted drug delivery. Studied material would aim on the tissue with high level of mannose receptors, such as tumorous cells or damaged tissues with immune respond.
Date: October 20, 2021
Fibrous materials represent very interesting structures with unique characteristics among other materials. They possess a high porosity, a large specific surface area and a good breathability. In addition, biopolymers and fibers thereof offer a whole range of opportunities in biomedical applications, such as wound healing, tissue engineering, and also cosmetics and dermatologics.
In this work, the focus was given to biopolymeric gums prepared by centrifugal spinning, which is an interesting approach with numerous advantages compared to electrospinning.1,2 Gum Arabica was used as the main material for the centrifugal spinning. This biocompatible and biodegradable polysaccharide can be prepared into 3D foams of fibrous materials with great prospects for biomedical application. The solution blends of Gum Arabica (GA) with several different concentrations and Poly(ethylene oxide) were tested. GA and PEO fibers were produced as novel carriers for entrapment of vitamin E and vitamin C.
The obtained blends of fibers from GA, PEO, and vitamins E and C were characterized by various means (Scanning Electron Microscopy and Attenuated Total Reflection-Fourier Transform Infrared). Most importantly, they were characterized by the release of vitamin E loaded in the GA and PEO fibers. The presentation will show that the newly prepared fibers represent a very promising material for cosmetic and dermatologic applications.
ACKNOWLEDGEMENTS: This work was supported by Technology Agency of the Czech Republic (TJ02000329) and CzechNanoLab project LM2018110 funded by MEYS CR is gratefully acknowledged for the financial support of the SEM and ATR-FTIR measurements at CEITEC Nano Research Infrastructure.
REFERENCES: [1] M. Krifa, W. Yuan, Text. Res. J. 86 (2016) 1294.; [2] M. Rihova et al, J Appl Polym Sci. 168 (2021) e49975.
Tissue engineering for regenerative medicine is a very complex research area with aims towards regenerative alternatives for transplantation needs. However, this discipline still has many limitations and thus offers potential for the development of various types of new organic, inorganic and hybrid materials applicable in this field. From this point of view, the novel hybrid materials play a major role in the development of advanced functional materials within many fields of human activities, whilst also showing huge potencial for future applications in biomedical branches.
This work focuses on the preparation of pure hybrid organic-inorganic (nano)fibres with a variety of unique properties such as mechanical and thermal resistance, flexibility and non-toxicity in the human body. Organosilane fibres are prepared by sol-gel method using one-pot syntesis followed by electrospinning techniques. By the above-mentioned methods is possible to prepare a layer of hybrid fibers without the presence of harmful additives and with a high molar content of hybrid precursore inside the silica matrix. Such newly prepared hybrid nanofibers evince biocompatibility together with further characteristics suitable for use in tissue engineering.
Resorbable tissue scaffolds that could support the patient´s cells or breathable wound dressings that could immobilize biocide particles are highly interested in regenerative medicine standing before the problem to replace non-functional tissues or improve the wound healing. The scaffold material should be biocompatible, biodegradable, and easy to manufacture, thus economically viable. A possible answer is to produce a structure made of a biodegradable polymer that mimics extracellular matrix (ECM), which would be peacefully received and gradually degraded when the new tissue has formed. The solution for wound dressings can also benefit from the nanofibrous structures with bioactive surfaces able to immobilize biomolecules and particles. One promising polymer is FDA-approved polycaprolactone (PCL) due to its relatively low cost, excellent processability, mechanical properties, non-toxicity, and low immunogenicity. However, the pristine form of PCL has a bioinert and hydrophobic surface causing problems with protein adsorption resulting in reduced cell adhesion. We have shown that PCL nanofibrous mats can be efficiently modified for both mentioned biomedical applications using plasma polymerization. Plasma polymerization being a subcategory of plasma-enhanced chemical vapor deposition (PECVD), was able to coat polymer nanofibers uniformly, and the deposition penetrated through the porous mat several tens of micrometers. We proved that it led to the formation of bioactive surfaces exhibiting increased cell attachment, adhesion strength and proliferation. We demonstrated attachment of biomolecules and drugs.
In the present study, the anti-bacterial and mechanical properties of the ZrN/Cu nanostructured coatings were studied. Copper was introduced as the anti-bacterial agent owing to its substantial activity against bacteria. Industrial reactive magnetron sputtering was utilized to synthesize the films with varying copper contents. Mechanical properties were measured using nanoindentation and discussed in relation to the chemical composition. The inhibitory efficiency of the films was tested against the two most common bacteria, including gram-negative (E. coli) and gram-positive (S. aureus) bacteria. We observed that the anti-bacterial efficiency of the samples significantly improved with increasing the copper amount. After 80 min exposure, the coatings with medium to high copper amount showed 100% activity against both types of bacteria. The highest hardness measured was 28 GPa for the low copper coating followed by a gradual decrease with increasing copper.
The extracellular matrix (ECM) of cells and, most notably, its mechanical properties significantly impact each cell's faith. Studies show that isometric forces generated by ECM or cell to cell interaction corresponds to different cell lines1. A classical approach to in vitro culturing on stiff surfaces such as plastic or glass does not recognize this, and so there is an increasing need for biocompatible materials with tunable properties such as stiffness, elasticity, or bioactivity.
In this study, we present a tunable hydrogel system prepared from Hyaluronic acid (HA), Serum albumin (BSA), and gelatin, cross-linked together by establishing EDC/NHS chemistry. By gradually increasing HA and BSA concentrations, we were able to prepare hydrogels with Young's Modulus (YM) ranging from 0.1 to 15 kPa. Mechanical properties, internal structure, layer thickness, swelling capacity, and hydrogel biocompatibility were characterized (Figure 1) by Atomic Force Microscopy (AFM), Holotomographic Microscopy (HM), Confocal microscopy, and viability assay.
Young's Modulus and actin structure of mouse embryonic fibroblasts were compared on hydrogels and standard cultivation surfaces. Results showed morphological and mechanical changes of cells on different hydrogels and stiff surfaces as glass or plastic. On softer hydrogels, cells were most abundant and showed rich actin structures such as lamellipodia and filopodia. Moreover, on 20 kPa hydrogel, cells tended to grow into the gel, corresponding to hydrogel characterization. Further experiments with HL-1 cells showed improved contractility response after Isoproterenol treatment of cells on hydrogels and increased cell monolayer formation.
ACKNOWLEDGEMENTS: This study demonstrated that our hyaluronan-based hydrogel system could be utilized as a better option for cell culture.
Polysaccharide/protein complex conjugates may represent a new dimension in the development of drug carrier structures. In our work, serum albumin/hyaluronic acid (BSA/HyA) potential drug delivery system have been developed via a simple and controllable charge neutralization technique without the use of toxic and hardly removable crosslinking agents, surfactants, and organic solvents. The pH - dependent quantitative characterization of the interaction between BSA and HyA macromolecules have been performed by surface plasmon resonance spectroscopy, particle charge titration, rheology, dynamic light scattering and turbidity measurement, circular dichroism and Fourier transformed infrared spectroscopy techniques. It was confirmed, that the pH as well as the applied BSA /HyA mass ratios strongly influence the size, the size distribution, the stability and the proposed core-shell structure of the potential drug carrier particles (approx. 200-210 nm). Besides the optimization of the preparation conditions, the drug encapsulation capacity of BSA/HyA nanocarriers and the dissolution profiles are also studied for ibuprofen and 2-picolinic acid as model drugs. The BSA/HyA conjugates prepared by charge neutralization may imply a novel possibility as controlled drug release carrier system in the future.
ACKNOWLEDGEMENTS: This research was supported by the National Research, Development and Innovation Office - NKFIH through GINOP-2.3.2-15-2016-0034, and FK131446. E. Csapó thanks the financial support of the “Momentum” Program of the Hungarian Academy of Sciences (LP2021-5). A. N. Kovács is thankful for support from the National Young Talent Scholarship (NTP-NFTO-20-B-0180).
Date: October 20, 2021
Nature is an inexhaustible source of ideas and materials. This time, chicken eggshell membrane, a natural product and waste material, has been discovered as a potential sulfur source for the production of sulfide. This is possible because of the presence of sulfur-containing amino acids in the proteins forming its fibers. In the present research eggshell membrane was high-energy ball milled with lead precursor to yield lead sulfide PbS, a semiconductor material suitable for the applications in solar cells.
Thus, a completely solid-state methodology (mechanochemical synthesis) without the need to use toxic precursors and solvents and elevated temperatures has been successfully applied. The effect of rotation speed and the type of lead precursor (acetate and nitrate) on the reaction course was investigated. The as-received powders were washed with distilled water, filtered and the content of lead in the filtrate reaction was measured by means of atomic absorption spectrometry. This provided a direct information about the reaction progress (reactants are water-soluble, whereas the produced PbS is not). The conversion reached 100% after 120 min of treatment at 750 rpm, whereas only around 60% conversion was achieved when milling at 500 rpm. The products were characterized by a vast number of characterization techniques, including XRD, low temperature N2 physisorption, SEM, TEM, XPS and electrochemical impedance spectroscopy using the Mott-Schottky analysis. The nanocrystalline character of the products was confirmed by XRD and TEM. At the end, the photocatalytic activity to degrade selected organic dyes of the products was tested.
Surface-enhanced Raman spectroscopy (SERS), is an analytical method based on plasmon enhancement and subdiffraction light focusing, occurring on noble metal nanostructures. It possesses a number of highly attractive properties, such as simplicity, compactness and low cost of equipment, ease of sample preparation, and extreme sensitivity. These features make SERS an unusually promising method for the analysis of biochemical or medical samples. At the same, the complexity of biologically significant compounds leads to extremely perplexing spectra, consisting of interfering signals from all chemical bonds present in the sample. Mediocre repeatability and frequent presence of variable background makes manual analysis even more problematic or almost impossible sometimes, limits the throughput of the method, and affects reliability. To address this problem, we suggest an automated interpretation of the SERS spectra with machine learning approaches. Spectra share many similarities with images, while convolutional neural networks (CNNs) achieve state-of-the-art image recognition results, thus making them a native choice for this problem. After slightly modification of CNN architecture to better fit the structure of the SERS data, it becomes able to recognize both quantitatively and qualitatively many biologically significant compounds. The method is of unusually high throughput, ability to cope with uneven data (a consequence of low repeatability), or even to fully control the equipment to achieve enough precision (under some assumptions).
Silica nanomaterials, whether natural or synthetic, are used in many areas of human activity. Natural silica nanomaterials often form very elegant and functional structures that perfectly fulfil their purpose. This is something that people try to imitate with the nanomaterials they make. The properties of synthetic silica nanomaterials can usually be improved by functionalization with organic molecules. However, there is only a limited amount of work involved in incorporating cyclodextrin molecules into the structure of silica nanoparticles, and these nanomaterials can only be applicable in a limited number of applications.
The new monosililated β-cyclodextrin derivative was prepared. Preparation path was optimised so that product does not need any special cleaning from byproducts. This new β-cyclodextrin derivative was subsequently used as a precursor for the preparation of silica nanoparticles, so that β-cyclodextrin is incorporated into the structure of particles not only on their surface. For bigger surface area there are pores in nanoparticles. The cyclodextrin precursor and the nanoparticles were characterized and are thus the starting point for further applications of cyclodextrin organosilica nanoparticles in many interesting fields such as pharmacy, where these nanoparticles can be used in systems for drug delivery, or as ecology, where can be used for water treatment.
Cancer continues to be a worldwide killer, despite the extensive research seen during the past decade. Among men, prostate cancer (PCa) is the most frequently diagnosed cancer disease. The gold standard in PCa diagnostics is analysis of the prostate specific antigen (PSA) level in blood serum. The serological PSA level is low in healthy men with an increased level observed after disruption of the basement membrane of the prostate gland. Since PSA is prostate specific rather than cancer specific, there is a need to find new, more specific biomarkers [1]. This work is focused on the detection of a sarcosine, which can be found in elevated levels in urine during PCa [2]. In this work, 2D nanomaterial MXene Ti3C2Tx was used to immobilise sarcosine oxidase (SOx) to fabricate a nanobiosensor exhibiting a detection limit of 18 nM and a linear range up to 7.8 µM. The prepared device also provides a response time of 2 s and recovery index of 102.6 % for detection of sarcosine spiked into urine samples.
ACKNOWLEDGEMENTS: We would like to acknowledge the support received from the Slovak Research and Development Agency APVV 17-0300 and the support from the ERC Proof of Concept grant (No. 825586).
REFERENCE: [1] Tkáč J. et al.; Prostate-specific antigen glycoprofiling as diagnostic and prognostic biomarker of prostate cancer, Interface Focus, 2019, Vol. 9, art. no. 20180077; [2] Sreekumar A. et al.; Metabolomic profiles delineate potential role for sarcosine in prostate cancer progression, Nature, 2009, Vol. 457, p. 910-914.
Date: October 21, 2021
TiO2 nanotube (TNT) layers produced by anodization of Titanium have been recognized as excellent biocompatible material owing to their low cytotoxicity, high stability, and antibacterial properties. As they possess also good hemocompatibility and anticoagulation characteristics, TNT layers are promising for vascular implants and biomedical mapplications due to excellent osteoblast cell adhesion and proliferation [1] and effective growth of hydroxyapatite [2]. These properties make them excellent as final surfaces for medical and dental implants based on Ti alloys.
In the present work investigates TiO2 nanotube (TNT) layers and their surface modifications by Atomic Layer Deposition (ALD) for the proliferation of Human Gingival Fibroblast cells. The key technique used in this study is bio-atomic force microscopy (bio-AMF). To study these cells, TNT layers (prepared via electrochemical anodization) with a distinct inner diameter of 12 nm, 15 nm and 100nm were used as substrates, as they appear to be the most suitable for the cell growth in general [3,4]. Additionally, TNT layers were coated by thin TiO2 coatings using ALD. An increase in cell growth and adhesion of the cells for all materials coated by 5 ALD cycles compared to their uncoated counterparts. The additional ALD TiO2 coatings changed the surface composition of all materials, while preserving the original structure and protected them from unwanted crystallization and shape changes. The presented approach of mild surface modification by ALD has a significant effect on the materials’ biocompatibility and is promising toward application in implant materials. In the presented work, we investigated the matrix elasticity (Young’s modulus, stiffness, adhesive force, and roughness) and nanotopography using the bio-AFM (atomic force microscopy) method.
REFERENCES: [1] Park, J.; et al., Nano Lett. 9 (2009) 9, 3157.; [2] Radtke, A.; et al. Nanomaterials 9 (2019) 123.; [3] Park, J.; et al. Small 6 (2009) 666.; [4] Motola, M.; et al. ACS Appl. Bio Mater. 3 (2020) 6447.
Regenerative medicine stands before the challenging task to develop suitable materials for scaffolds in tissue engineering or dressings for chronic wound healing. Although synthetic polymers are favoured because of simple manufacturing, lacking bioactivity complicates their applicability. The introduction of polar surface groups increases the surface free energy making the polymer hydrophilic which improves cell adhesion or can mediate immobilization of proteins. We have demonstrated that plasma polymers (PPs) containing amine functional groups can successfully coat all kinds of non-planar polymer substrates used in bioapplications, such as culture dishes and well plates, porous scaffolds, or nanofibrous mats [1]. Amine PP coating ensures biocompatibility of polycaprolactone nanofibers [2] and influences cell adhesion with clear differences between endothelial and non-endothelial cells [3]. To fully understand the cell behaviour, it is necessary to investigate the interaction of PP-coated materials with extracellular matrix (ECM) proteins. Since the adsorption of proteins from blood or sera is an initial phase of cell attachment it can highly affect cell viability. Therefore, we investigated the immobilization of an ECM protein, collagen, on amine and carboxyl PPs in the present study. Cell proliferation tests of keratinocytes and vascular smooth muscle cells followed the successful collagen binding. A unique method, scanning probe microscopy with a collagen-functionalized probe, was used to assess the collagen adhesion to PP coatings.
REFERENCES: [1] M. Michlíček et al., Appl. Surf. Sci. 540, 147979 (2021).; [2] I. Nemcakova et al., Int. J. Mol. Sci. 21, 9467 (2020).; [3] P. Černochová et al., Sci. Reports 10, 9357 (2020).
Human dental enamel is a nanocomposite material with hierarchically organized structure over several orders of magnitude. The basic building units are hydroxylapatite (Ca5(PO4)3(OH)) nanocrystals of few tens of nm width and up to µm length. The nanocrystals constitute ca. 5 µm wide and up to millimeter long units, called enamel prisms. The formation of the hierarchical structure is biochemically controlled by the changing functional activity of the ameloblasts. These enamel producing cells in the initiation and termination periods produce the so called aprismatic layers. In our recent work it has been shown that mechanical properties of sound primary dental enamel may be markedly different along enamel growth direction [1]. Here we explore the structural background of these differences. Scanning electron microscopy (SEM) observations were performed on etched surface of cross sectional sample of sound primary dental enamel to follow the prism growth direction. Focused ion beam (FIB) milling was applied to sample the different zones investigated by nanoindentation. Pairs of FIB lamellae - one perpendicular and other parallel to the prism elongation direction - have been extracted from three locations along the enamel growth directions: near surface, 550 µm and 1100 µm from surface. Selected area electron diffraction (SAED) patterns have been obtained and and an evaluation procedure was developed to explore the complicated ring structure. Based on the intensity distribution along electron diffraction rings the texture properties of the three zones were assessed and interpreted in relation with nanoindentation data.
REFERENCE: [1] Kis, VK., Sulyok, A., Hegedűs, M., Kovács, I., Rózsa, N., Kovács, Zs, Acta Biomaterialia 120 (2021) 104-115.
Pure Titanium and Ti6Al4V alloy are biocompatible materials that are commonly used for medical bone implants. Femtosecond laser ablation produces LIPSS (“laser induced periodic surface structures”) which consist of micro-cones and nano-ripples. Hence, surface modification by femtosecond laser and electrochemical anodization could be promising methods for improving both osteointegration and osteo-repellence properties of the implants. The aim of this work is electrochemical characterization of oxidized Ti and Ti6Al4V alloy treated by femtosecond laser. Firstly, pure Titanium and Ti6Al4V samples were potentiostaticaly anodized up to 100V in 25% phosphoric acid. Following the potentiostatic anodization samples were treated with femtosecond laser. As a final step, laser treated spots were anodized potentiodynamicaly up to 10V using SDCM (Scanning Droplet Cell Microscopy). Influence of different electrolytes, scan rates and potentials were examined and optimized, consequently. Topography and morphology were determined by the means of AFM (Atomic Force Microscopy) and SEM (Scanning Electron Microscopy), while crystallography by the XRD (X-Ray Diffraction). Furthermore, the composition of the oxide layer was determined by the EDX. Film formation factor (kox), as well as relative permittivity εr were calculated from the experimental data. Finally, obtained results can indicate that anodized and subsequently femtosecond laser treated samples could be used as medical bone implants.