Atomic Force Microscopy Methods Research Articles

Pluronic P123/DMSO Lyotropic Liquid Crystal for Incorporating Bioactive Substances for Topical Application.

Lyotropic liquid crystals (LLCs) have attracted considerably growing interest in drug delivery applications over the last years. The structure of LLC matrices is complementary to cell membranes and provides an efficient, controlled, and selective release of drugs. In this work, a complex of experimental methods was used to characterize binary LLCs Pluronic P123/DMSO and triple LLC systems Pluronic P123/DMSO/Ibuprofen, which are interesting as transdermal drug delivery systems. Liquid crystalline, thermal, and rheological properties of LLCs were studied. Concentration and temperature areas of the lyomesophase existence were found, and phase transition enthalpies were evaluated. Intermolecular interactions among the components were studied by infrared (IR) spectroscopy. In vitro studies of Ibuprofen (Ibu) release from various LLCs allow differentiation of its release depending on the polymer content. Atomic force microscopy and contact angle methods were used to characterize the surface morphology of the hydrophobic membrane, which was used as a stratum corneum model, and also evaluate the adhesion work of the LLCs. A complex analysis of the results provided by these experimental methods allowed revealing correlations between the phase behavior and rheological characteristics of the LLCs and release kinetics of ibuprofen. The proposed biocompatible systems have considerable potential for a transdermal delivery of bioactive substances.

Enhancing biocompatibility and osseointegration of medical implants using ti based nanocomposite coatings

The surface of the replacement medical implant can be coated, which is one of the most basic and effective ways to develop and strengthen bones and increase their compatibility for the human body to solve problems with bone defects, such as the problem of releasing ions from some elements of the body Medical alloy implants are one of the major drawbacks in bone fracture surgery, and biocompatible implants are new ways to ensure that these implants work well. These implants play a major role in accelerating osseointegration processes, but at the same time they suffer from the problem of releasing niobium and zirconium ions, which may cause serious diseases to human health. To stop these toxic ions from releasing, a bioceramic nanolayer coating was put on the alloy's surface. This made it more biocompatible and stopped the toxic ions from escaping. Among several types of coatings, the best nanocomposite coating was selected. Three criteria and levels were used: voltage, time, and cocentartion. A Takeuchi statistical program was used to collect data on all the tests (thickness, adhesion, contact angle, and roughness) in order to find the best coated sample. The study then used atomic force microscopy (AFM) and field emission scanning electron microscopy (FE-SEM) methods.

Study of the Fenton Oxidative Reaction on a Culture of Human Fibroblast Cells Incubated with Ablated CeO<sub>2</sub> Particles

Purpose. Study of the bioprotective properties of ablated cerium dioxide nanoparticles in relation to immortalized human fibroblasts under conditions of oxidative stress caused by the Fenton reaction.Methods. Cerium dioxide nanoparticles with pronounced antioxidant properties were obtained using laser ablation. The average maximum sizes of ablated particles of oxidized cerium in non-centrifuged and centrifuged at a speed of 1000 rpm nanodispersed aqueous solutions were revealed using the method of atomic force microscopy. The spectrophotometric method revealed that ablated cerium dioxide nanoparticles exhibit antioxidant properties and prevent the degradation of the methylene blue dye during the Fenton reaction. Cell culture samples were mapped using scanning electron microscopy using an energy-dispersive attachment after their incubation with ablated cerium dioxide nanoparticles. Using MTT analysis, the effect of ablated cerium dioxide nanoparticles on the survival of BJ TERT cell culture in the Fenton reaction was studied. Non-centrifuged and centrifuged at a speed of 1000 rpm nanodispersed solutions of oxidized cerium were used. The antioxidant activity of cerium dioxide nanoparticles after 6- and 24-hour incubation was studied.Results. The average limiting sizes of ablated cerium dioxide nanoparticles have been established, the values of which are (61,95±0,1) nm for a non-centrifuged aqueous solution and (56,59±0,1) nm for an aqueous solution centrifuged at a microcentrifuge speed of 1000 rpm. It was revealed that in the presence of ablated cerium dioxide nanoparticles, the degree of oxidative degradation of methylene blue during the Fenton reaction was significantly reduced. It was found that with an increase in the concentration of ablated cerium dioxide nanoparticles from 20 to 1000 mg/l, their antioxidant effect increased. From the obtained SEM images of cell cultures with ablated cerium dioxide nanoparticles, it follows that the nanoparticles are captured by cells during incubation and can have a significant effect on oxidative processes during the Fenton reaction. Statistical analysis based on the results of the MTT assay showed that 6-hour and 24-hour incubation with ablated cerium dioxide nanoparticles had a pronounced protective effect on the BJ TERT cell line.Conclusion. This work shows that during the Fenton reaction, cerium dioxide nanoparticles prevent the oxidative degradation of the methylene blue dye. When immortalized human fibroblasts are incubated, ablated cerium oxide nanoparticles are taken up by the cells and have a significant protective effect on them in the oxidative reaction. The high antioxidant activity of nanoparticles is determined by the high content of functional defects on the surface of nanoparticles obtained under sharply nonequilibrium conditions of laser ablation.

Compressed sensing reconstruction of cell mechanical images obtained from atomic force microscopy

Compressed sensing (CS), a technique in signal processing that reconstructs sparse signals from a limited sampling number, has been valuable in topographic images obtained from atomic force microscopy (AFM). However, how CS is effective in reconstructing AFM mechanical images remains unclear. We investigated the reconstruction of topographic and mechanical images of living cells, such as developing embryos obtained from AFM mapping experiments using CS. The results showed that both topographic and mechanical images of embryonic cells in the different developmental stages were well reconstructed at a spatial resolution higher than the original AFM images. These results suggested that the CS approach enabled the cell mechanical properties, together with cell surface morphology, using AFM mapping measurements to be faster than the conventional AFM methods without reducing the spatial resolution.

Microstructure and Properties of Thin-Film Submicrostructures Obtained by Rapid Thermal Treatment of Nickel Films on Silicon

Nickel films of 40 nm thickness were obtained by means of magnetron sputtering on a single-crystalline silicon substrate. The films were subjected to rapid thermal treatment (RTT) for 7 s until the temperature increased from 200 to 550 °C. By means of the X-ray diffraction method, the structural-phase composition of nickel films before and after RTT was explored. The atomic force microscopy method due to direct contact with the surface under study, made it possible to accurately define the microstructure, roughness, specific surface energy and grain size of the nickel films before and after RTT, as well as to establish the relationship of these parameters with the phase composition and electrical properties of the films. Surface specific resistance was measured using the four-probe method. Based on XRD results, formation of Ni2Si and NiSi phases in the film was ascertained after RTT at 300 °C. At RTT 350–550 °C, only the NiSi phase was formed in the film. The microstructure and grain size significantly depend on the phase composition of the films. A correlation has been established between specific surface energy and resistivity with the average grain size after RTT at 350–550 °C, which is associated with the formation and constant restructuring of the crystal structure of the NiSi phase.

Single cell mechanics analyzed by atomic force microscopy and finite element simulation

Cell mechanics plays a key role in determining physical performances and physiological functions of cells, as well as the early detection of diseases and development of biomedical engineering. In this study, we utilized a combination of atomic force microscopy (AFM) and finite element method (FEM) to compare the cellular elasticity (Young’s modulus) and viscoelasticity (stress-relaxation time) of living and fixed endothelial cells (ECs) across varying loading rates. The results showed that both mechanical properties of normal ECs are more sensitive to loading speed compared with fixed ECs. The Young’s modulus of normal endothelial cells (ECs) exhibits an increasing trend with the growing loading rate, whereas the Young’s modulus of fixed ECs is almost not affected by the loading rate. Among various viscoelastic properties of cells under varying loading rates, the long-term relaxation time, especially at a loading rate of 5 μm s−1, showed the most significant difference between living and fixed cells. This work comprehensively evaluated the effectiveness of using different mechanical properties to distinguish cells with different physiological characteristic. This research would improve our knowledge of single-cell mechanical behaviors and provide new ideas for distinguishing various types of cells by AFM-based cellular elastic and viscoelastic properties with varying loading rates.

High nonlinear optical efficiency in zinc(II) and copper(I) stilbene based iminopyridine complexes: Absorption, emission analysis and advanced characterization

The novelty of this work lies in the comprehensive studies of the spectroscopic and third-order nonlinear optical properties of zinc(II) and copper(I) stilbene based iminopyridine complexes. Our previous work involved the synthesis as well as the characterization of both the free ligand and these its corresponding metal complexes and conducting quantum chemical calculations on their molecular orbitals, shedding light on their charge transfer and π-π* interactions. This makes these materials promising models for supramolecular assemblies. Thin films, obtained using the spin coating method, are characterized using Atomic Force Microscopy and Ellipsometry methods. These techniques provide valuable information about the physical properties of the layers, such as homogeneity, roughness and linear refractive index. Moreover, we present spectroscopic analysis that involve the absorption and emission of light, along with the decay time of photoluminescence in the thin films. Through advanced techniques like the Maker fringe method for third harmonic generation and the Z-scan method for recording nonlinear absorption and refraction, we demonstrate the high nonlinear optical efficiency of these complexes. This study presents how specific structural elements impacts tailoring in the enhancement of the NLO properties of these complexes. These findings underscore the potential of zinc(II) and copper(I) stilbene based iminopyridine complexes in nonlinear optics and photonics applications.

One-Step Non-Contact Additive LIFT Printing of Silver Interconnectors for Flexible Printed Circuits

The single-pass one-step method for printing conductive silver tracks on a glass surface, using the laser-induced forward transfer (LIFT) technique, was proposed, providing a unique opportunity for high-throughput printing of surface micro- and nanostructures with high electrical conductivity and positioning accuracy. This method was developed via our multi-parametric research, resulting in the selection of the optimal material, laser irradiation, and transfer conditions. Optical, scanning and transmission electron, and atomic force microscopy methods, as well as X-ray diffraction, were used to characterize the surface structure and phase state of the printed structures, while energy-dispersive X-ray and X-ray photoelectron microscopy were employed for their chemical microanalysis. Depending on the laser irradiation parameters, the specific electrical conductivity of the printed tracks varied from 0.18 to 83 kS/cm, approaching that of donor magnetron-sputtered films. This single-pass one-step method significantly facilitates fast, large-scale, on-demand local laser printing of metallic (sub)microcomponents of microelectronic devices.

Effect of welding speed on microstructure, nano-mechanical and nano-tribological characteristics of dissimilar friction stir welded AA6061-T6 and AZ31 alloy

The microstructural, tribological, and mechanical performance of friction-stir welded AA6061-T6 and AZ31 alloys were investigated using electron back scattered diffraction, scanning electron microscope, X-ray diffraction, and electron dispersed spectroscopy methods. The non-destructive X-ray microcomputed tomography test was used to analyse weld porosity. The distribution of volumetric and surface flaws (pores) was found to be confined across the weldment. Using a novel atomic force microscopy method, the nano-tribological characteristics of the base metal and localized regions of welded sample were studied for the first time. The significant difference in wear and friction behaviour was observed in all weld zones and base metal of magnesium side, which was correlated with the hardness of these regions. AFM results showed strong variation in tribological properties in correlation with the hardness trends of different weld zones, i.e. higher hardness leads to low wear. In weldments, intermetallic compounds such as Al12Mg17 and Al3Mg2 were produced, resulting in nanohardness differences as measured by the nanoindentation test. The joint efficiency of 65%, 84%, and 91% were obtained at welding speeds of 16 mm/min, 20 mm/min, and 25 mm/min, respectively.

Window Fabrication of Zinc Selenide Nanostructures: Synthesis and Properties

Zinc selenide (ZnSe) nanostructure’s optical and structural characteristics were investigated in this study. Pulse laser deposition of thin films on glass substrates was achieved using an Nd:YAG laser (wavelength 1064 nm) at different laser powers (100, 200, 300, 400 and 500 mJ) with fixed pulses 100 pulses, repetition rate 6 Hz and distance 10 cm between laser and the substrate with a thickness of films 200 nm. An atomic force microscope (AFM) and X-ray diffraction method were used to research the impact of altering the laser intensity on the structural characteristics. A branched (100) polycrystalline type and a plane (111) and branched (100) polycrystalline type are prevalent (002). In addition, AFM measurements further revealed that the smallest granular size achieved at high laser power was 48.40 nm at 100 mJ. The findings showed that it is possible to construct nanostructures with medium grain sizes of alumina (72.99 nm). The study of the relationship between laser energy and nanostructure optical characteristics was explored and it was discovered that the transitions had a specific range of 2.83–3.10 eV.

Transforming Wood into a High-Performance Engineering Material via Cellulose Nanocrystal Impregnation

Abstract The demand for wood in construction has led to shortages of strong wood types, causing a shift to costlier alternatives like concrete and nonbiodegradable materials, prompting the investigation of modifying softwoods for better engineering properties. This study investigates the optimization of a multistep impregnation process utilizing functionalized cellulose nanocrystals (f-CNCs) to enhance softwood properties. The process involves alkali delignification, ultrasonication, and vacuum pressure treatment to improve wood porosity and in turn improve CNC impregnation with uniform dispersion. Microstructural analyses through field emission scanning electron microscopy and atomic force microscopy (AFM) offer detailed insights into cell wall morphology and surface topography, whereas Fourier transform infrared spectroscopy highlights compositional shifts resulting from f-CNC impregnation. Mechanical testing demonstrates significant improvements for treated woods, particularly a 67 percent increase in modulus of elasticity for the 2 percent CNC-treated group compared with the control group; a 71 percent increase in modulus of rupture was observed for 2 percent CNC-, 3 percent NaOH-, and 2 percent acetic acid-treated group compared with the control sample. The sample delignified with 3 percent NaOH and impregnated by 2 percent f-CNC emerged as particularly effective. This research sets the stage for potential advancements in strengthening softwood using CNC, including a novel AFM method and alternative impregnation techniques like the Lowry method, inviting further exploration.

Nanostructure and thermal characteristics of silica/human serum albumin systems based on a modified nanosilica entero-vulnerosorbent.

Entero-vulnerosorbents based on geometrically modified (GM) (mechanical treatment at different times, tMT = 1, 4, and 7 h) fumed nanosilica A300 (NS) and protein molecules (human serum albumin/GM-nanosilica systems) were characterized with a focus on their surface, morphology, topography, and thermal properties. Microscopic, spectroscopic, and analytical techniques, including atomic force microscopy (AFM), optical profilometry (OP), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and elemental analysis (CHN), were used. The differentiation in the surface morphology, micro-nanoroughness, surface chemistry, thermal properties of the silica support, and protein/nanosilica systems were found. AFM, OP, and HRTEM microscopic methods showed that the albumin/silica composite surface is less rough, wavy, and asymmetrical; it is also smoother, flat, and homogeneous because of the formation of a continuous layer of a protein film on the support surface. CHN, XPS, and S/TEM-EDX analysis showed that HSA adsorbed on the unmodified and GM-treated silica carrier led to variations in the physical and chemical features of materials (elemental composition, element concentration, chemical states, chemical bonds between enzyme molecules, and silica surface). Thermal studies were carried out using a thermogravimetric technique linked with a quadrupole mass spectrometer (TG/DTG/DSC-QMS). The degradation of the HSA/nanosilica system is a two-stage process that takes place within the temperature range 160-450-900 °C.

Paticularities of radiation defect formation in ceramic barium cerate

The results of the investigations are presented on the effect of irradiation with electrons, ions of inert gases (Ne, Ar, Kr) and oxygen on the structure and properties of Nd-doped barium cerate by the methods of X-ray diffraction analysis, scanning electron and atomic force microscopy, thermal desorption spectroscopy. It is shown that the low-energy irradiation with Ne and Ar ions stimulates the blistering processes on the surface, whereas the high energy ion irradiation by Ne, Ar, Kr ions the cerate surface undergoes the following stages of the spherulite growth - nucleation, growth (view of cauliflower), formation of spherulitic crust, correspondingly. The similar structures were not observed in the case of irradiation with high-energy oxygen ions. It is noticed that the irradiation of cerates with electrons leads to the formation of nano-sized acicular structures on the surface. The radiation of lowenergy ions of inert gases led to the conversion of most of the neodymium into a tetravalent state, as has been shown, accompanied by an increase in oxygen release and a decrease in water compared to non-irradiated cerate, as well as the independence of the amount of gases from the type of ions. Based on the data on thermal desorption of water and oxygen molecules from the irradiated barium cerate it was assumed that the irradiation stimulates the oxidation to Nd4+.

Mechanical Properties of the Carbonized Layer Formed by Ion Flow Orientated at Different Angles to the Polyurethane Surface.

Polymer materials are widely used in medicine due to their mechanical properties and biological inertness. When ion-plasma treatment is used on a polymer material, a carbonization process occurs in the surface nanolayer of the polymer sample. As a result, a surface carbonized nanolayer is formed, which has mechanical properties different from those of the substrate. This layer has good biocompatibility. The formation of a carbonized nanolayer on the surface of polymer implants makes it possible to reduce the body's reaction to a foreign body. Typically, to study the properties of a carbonized layer, flat polymer samples are used, which are treated with an ion flow perpendicular to the surface. But medical endoprostheses often have a curved surface, so ion-plasma treatment can occur at different angles to the surface. This paper presents the results of a study of the morphological and mechanical properties of a carbonized layer formed on a polyurethane surface. The dependence of these properties on the directional angle of the ion flow and its fluence has been established. To study the surface morphology and elastic properties, methods of atomic force microscopy and methods of elasticity theory were used. The strength properties of the carbonized layer were studied using a stretching device combined with a digital optical microscope.

Crack resistance of carbonized layer of multilayer polyurethane with nanofillers. Combination of casting, solution, carbonization by ion implantation technologies

The paper describes the results of an experimental study of a polyurethane material treated by ion implantation technology. The problems of crack growth in the near-surface layer carbonized by ion treatment were investigated using digital optical microscopy. The methods of atomic force microscopy allowed studying the possibility of carbonized layers delamination from the substrate. As a result, the technology for the production of a multilayer polyurethane material with nanofillers (nanotubes, nanodiamonds, fullerenes, graphenes) and its optimal modification by ion implantation treatment was developed, which makes it possible to improve the biocompatibility of polyurethane implants with human tissues.

Studies on physical properties of tin oxide films

This paper reports the study of some physical properties of thin films of tin oxide, such as the structural properties, surface morphology and optical transmission and reflection. The thin films of tin oxide were deposited by the method of thermal evaporation under vacuum. Transmission electron microscopy (TEM) was used to study the structural properties and the atomic force microscopy (AFM) method was used to study the surface morphology of thin films of tin oxide. The absorption and extinction coefficients of the investigated thin layers were determined from the transmittance and reflectance spectra recorded in the range of wavelengths between 190 and 1100 nm.

Impact of Swelling on Macroscopic and Nanoscopic Mechanical Properties of Amphiphilic Polymer Co‐Networks in Non‐Selective and Selective Solvents

AbstractAmphiphilic polymer gels show environmentally sensitive mechanical properties depending on the solvent polarity, which makes them useful for applications in soft contact lenses, membranes, drug delivery systems, and tissue engineering. To rationally design the material properties for such applications, a sound knowledge about the mechanical properties at different solvency states is necessary. To acquire such knowledge, amphiphilic networks are prepared by hetero‐complementary coupling of amine‐terminated tetra‐poly(ethylene glycol) (t‐PEG‐NH2) with 2‐(4‐nitrophenyl)‐benzoxazinone terminated tetra‐poly(ε‐caprolactone) (t‐PCL‐Ox). The mechanical properties are investigated on different length‐scales and under non‐selective and selective solvent conditions using shear rheometry and atomic force microscopy (AFM). The swelling as well as the modulus in good solvent are in accord with scaling laws found for other four‐arm star‐shaped polymer networks and theoretical predictions. The swelling in selective solvent reveals a concentration‐independent volume swelling degree and a nearly linear scaling of the modulus with concentration. The surface topography probed by AFM reveals microphase‐separated structures in the range of 20 nm. Similar modulus values are obtained for bulk films in water using the complementary methods of atomic force microscopy and rheometry. The data are compared with pure hydrophilic networks to identify the effect of amphiphilicity on the material properties.

Label-Free Detection of CA19-9 Using a BSA/Graphene-Based Antifouling Electrochemical Immunosensor.

Evaluating the levels of the biomarker carbohydrate antigen 19-9 (CA19-9) is crucial in early cancer diagnosis and prognosis assessment. In this study, an antifouling electrochemical immunosensor was developed for the label-free detection of CA19-9, in which bovine serum albumin (BSA) and graphene were cross-linked with the aid of glutaraldehyde to form a 3D conductive porous network on the surface of an electrode. The electrochemical immunosensor was characterized through the use of transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscope (AFM), UV spectroscopy, and electrochemical methods. The level of CA19-9 was determined through the use of label-free electrochemical impedance spectroscopy (EIS) measurements. The electron transfer at the interface of the electrode was well preserved in human serum samples, demonstrating that this electrochemical immunosensor has excellent antifouling performance. CA19-9 could be detected in a wide range from 13.5 U/mL to 1000 U/mL, with a detection limit of 13.5 U/mL in human serum samples. This immunosensor also exhibited good selectivity and stability. The detection results of this immunosensor were further validated and compared using an enzyme-linked immunosorbent assay (ELISA). All the results confirmed that this immunosensor has a good sensing performance in terms of CA19-9, suggesting its promising application prospects in clinical applications.

Characterizing Morphometric and Nanomechanical Malignant Cell Features in a Rare Paediatric γδ T-acute Lymphoblastic Leukaemia: Insights from a Single Case Study Using Atomic Force Microscopy

The most common cancer in paediatric age is acute lymphoblastic leukaemia (ALL) which accounts for nearly a quarter of all cases of paediatric cancer. ALL cases are classified as B-cell or T-cell precursor ALL, based on their immunophenotypical features. Patients with T-cell ALL (T-ALL) comprise 10–15% of all newly diagnosed cases and are more prevalent in boys and in older age compared to the overall incidence peak age of ALL. In this case report, we present the morphometric and nanomechanical features of T-lymphoblasts derived from an 11-month-old infant with a rare subtype of γδ T-ALL with aggressive biological behavior. To investigate these features, we employed atomic force microscopy (AFM) and compared the blast cell deviations found in their nanostructure and elasticity to those of normal lymphocytes from a healthy child. The malignant T-lymphoblasts exhibited reduced roughness and Young’s modulus values. This single case analysis demonstrates the potential of the AFM method to provide additional information regarding the characteristics of malignant cells and suggests its potential as a complementary approach for distinguishing neoplastic cells from normal cells. The application of AFM could potentially facilitate the introduction of in vitro tests to determine the efficacy of anti-leukemic treatments.

The Role H-Bonding and Supramolecular Structures in Homogeneous and Enzymatic Catalysis

The article analyzes the role of hydrogen bonds and supramolecular structures in enzyme catalysis and model systems. Hydrogen bonds play a crucial role in many enzymatic reactions. However, scientists have only recently attempted to harness the power of hydrogen bonds in homogeneous catalytic systems. One of the newest directions is associated with attempts to control the properties of catalysts by influencing the “second coordination sphere” of metal complexes. The role H-bonding, and the building of stable supramolecular nanostructures due to intermolecular H-bonds, based on catalytic active heteroligand iron (Fe) or nickel (Ni) complexes formed during hydrocarbon oxidations were assessed via the AFM (Atomic-force microscopy) method, which was proposed and applied by authors of this manuscript. Th is article also discusses the roles of hydrogen bonds and supramolecular structures in oxidation reactions catalyzed by heteroligand Ni and Fe complexes, which are not only effective homogeneous catalysts but also structural and functional models of Oxygenases.