XPS Modeling of Immobilized Recombinant Angiogenin and Apoliprotein A1 on Biodegradable Nanofibers

The immobilization of viable proteins is an important step in engineering efficient scaffolds for regenerative medicine. For example, angiogenin, a vascular growth factor, can be considered a neurotrophic factor, influencing the neurogenesis, viability, and migration of neurons. Angiogenin shows an exceptional combination of angiogenic, neurotrophic, neuroprotective, antibacterial, and antioxidant activities. Therefore, this protein is a promising molecule that can be immobilized on carriers used for tissue engineering, particularly for diseases that are complicated by neurotrophic and vascular disorders. Another highly important and viable protein is apoliprotein A1. Nevertheless, the immobilization of these proteins onto promising biodegradable nanofibers has not been tested before. In this work, we carefully studied the immobilization of human recombinant angiogenin and apoliprotein A1 onto plasma-coated nanofibers. We developed a new methodology for the quantification of the protein density of these proteins using X-ray photoelectron spectroscopy (XPS) and modeled the XPS data for angiogenin and apoliprotein A1 (Apo-A1). These findings were also confirmed by the analysis of immobilized Apo-A1 using fluorescent microscopy. The presented methodology was validated by the analysis of fibronectin on the surface of plasma-coated poly(ε-caprolactone) (PCL) nanofibers. This methodology can be expanded for other proteins and it should help to quantify the density of proteins on surfaces using routine XPS data treatment

Immobilization of Platelet-Rich Plasma onto COOH Plasma-Coated PCL Nanofibers Boost Viability and Proliferation of Human Mesenchymal Stem Cells

The scaffolds made of polycaprolactone (PCL) are actively employed in different areas of biology and medicine, especially in tissue engineering. However, the usage of unmodified PCL is significantly restricted by the hydrophobicity of its surface, due to the fact that its inert surface hinders the adhesion of cells and the cell interactions on PCL surface. In this work, the surface of PCL nanofibers is modified by Ar/CO2/C2H4 plasma depositing active COOH groups in the amount of 0.57 at % that were later used for the immobilization of platelet-rich plasma (PRP). The modification of PCL nanofibers significantly enhances the viability and proliferation (by hundred times) of human mesenchymal stem cells, and decreases apoptotic cell death to a normal level. According to X-ray photoelectron spectroscopy (XPS), after immobilization of PRP, up to 10.7 at % of nitrogen was incorporated into the nanofibers surface confirming the grafting of proteins. Active proliferation and sustaining the cell viability on nanofibers with immobilized PRP led to an average number of cells of 258+-12.9 and 364+-34.5 for nanofibers with ionic and covalent bonding of PRP, respectively. Hence, our new method for the modification of PCL nanofibers with PRP opens new possibilities for its application in tissue engineering

Different concepts for creating antibacterial yet biocompatible surfaces: Adding bactericidal element, grafting therapeutic agent through COOH plasma polymer and their combination

Antibacterial coatings have become a rapidly developing field of research, strongly stimulated by the increasing urgency of identifying alternatives to the traditional administration of antibiotics. Such coatings can be deposited onto implants and other medical devices and prevent the inflammations caused by hospital-acquired infections. Nevertheless, the design of antibacterial yet biocompatible and bioactive surfaces is a challenge that biological community has faced for many years but the "materials of dream" have not yet been developed. In this work, the biocompatible yet antibacterial multi-layered films were prepared by a combination of magnetron sputtering (TiCaPCON film), ion implantation (Ag-doped TiCaPCON film), plasma polymerization (COOH layer), and the final immobilization of gentamicin (GM) and heparin (Hepa) molecules. The layer chemistry was thoroughly investigated by means of FTIR and X-ray photoelectron spectroscopies. It was found that the immobilization of therapeutic components occurs throughout the entire thickness of the plasma-deposited COOH layer. The influence of each type of bactericide (Ag+ ions, GM, and Hepa) on antibacterial activity and cell proliferation was analyzed. Our films were cytocompatible and demonstrated superior bactericidal efficiency toward antibioticresistant bacterial E. coli K261 strain. Increased toxicity while using the combination of Ag nanoparticles and COOH plasma polymer is discussed

In situ TEM measurements of mechanical properties of individual spherical BN nanoparticles of different morphologies

Boron nitride (BN) nanostructures exhibit excellent mechanical properties. For example, the in situ tensile tests on individual BN nanotubes (BNNTs), which were conducted in situ in a transmission electron microscope (TEM) column, demonstrated the strength and Young’s modulus of ~33 GPa and ~1.3 TPa, respectively [1].Such superb mechanical properties of BN nanostructures make them very attractive materials as a reinforcement phase in lightweight composites. Besides nanotubes, nano-BN can be obtained in the form of spherical nanoparticles (BNNPs) with different morphologies – solid or hollow, with smooth or rough surfaces. High electrical and chemical resistance, thermal stability and biocompatibility of BNNPs were reported but their mechanical properties have not been detailed yet

Compressive properties of hollow BN nanoparticles: theoretical modeling and testing using a high-resolution transmission electron microscope

Due to excellent mechanical properties, nanoparticles have a great potential as reinforcing phase in composite materials, friction modifiers in liquid lubricants, catalysts and drug-delivery agents. In the present study the mechanical analysis of individual spherical hollow BN nanoparticles (BNNPs) using a combination of in situ compression tests inside a high-resolution TEM and theoretical modeling was conducted. It was found that BNNPs display a high mechanical stiffness and a large value of elastic recovery. This enables the hollow BNNPs to exhibit considerably large cyclic deformation (up to 30% of the sphere’s original external diameter) and to accumulate plastic deformation of approximately 30% of the total compression strain. Theoretical simulations allowed for elucidation of BNNPs structural changes under compression at the atomic level and explained the origin of their high stiffness and large critical deformation values

Growth of spherical boron oxynitride nanoparticles with smooth and petalled surfaces during a chemical vapour deposition process

A rich variety of hollow and solid (without internal hollow spaces) spherical boron oxynitride nanoparticles (BNO-NPs) with smooth or petalled surfaces were synthesized during a boron oxide-assisted chemical vapour deposition (BOCVD) process. Diverse BNO-NPs were obtained while utilizing different precursors, gas flow rates and synthesis temperatures in the range of 1200–1430 °C. The BNO-NP morphologies, atomic structures and spatially-resolved chemical compositions were studied by scanning (SEM) and transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray, Fourier-transform infrared and confocal Raman spectroscopy. Particle size distributions were measured using dynamic light scattering under visual microscopic control. A growth model of different spherical BNO-NP types based on the detailed analysis of physical–chemical processes at different BOCVD stages was proposed. A new type of spherical BNO-NPs of “hedgehog” morphologies with BN nanowires on their surfaces was first predicted in accordance with the designed model and then experimentally verified

Effect of BN nanoparticles loaded with doxorubicin on tumor cells with multiple drug resistance

Herein we study the effect of doxorubicin-loaded BN nanoparticles (DOX-BNNPs) on cell lines that differ in the multidrug resistance (MDR), namely KB-3-1 and MDR KB-8-5 cervical carcinoma lines, and K562 and MDR i-S9 leukemia lines. We aim at revealing the possible differences in the cytotoxic effect of free DOX and DOX-BNNP nanoconjugates on these types of cells. The spectrophotometric measurements have demonstrated that the maximum amount of DOX in the DOX-BNNPs is obtained after saturation in alkaline solution (pH 8.4), indicating the high efficiency of BNNPs saturation with DOX. DOX release from DOX-BNNPs is a pH-dependent and DOX is more effectively released in acid medium (pH 4.0–5.0). Confocal laser scanning microscopy has shown that the DOX-BNNPs are internalized by neoplastic cells using endocytic pathway and distributed in cell cytoplasm near the nucleus. The cytotoxic studies have demonstrated a higher sensitivity of the leukemia lines to DOX-BNNPs compared with the carcinoma lines: IC50(DOX-BNNPs) is 1.13, 4.68, 0.025, and 0.14 μg/mL for the KB-3-1, MDR KB-8-5, K562, and MDR i-S9 cell lines, respectively. To uncover the mechanism of cytotoxic effect of nanocarriers on MDR cells, DOX distribution in both the nucleus and cytoplasm has been studied. The results indicate that the DOX-BNNP nanoconjugates significantly change the dynamics of DOX accumulation in the nuclei of both KB-3-1 and KB-8-5 cells. Unlike free DOX, the utilization of DOX-BNNPs nanoconjugates allows for maintaining a high and stable level of DOX in the nucleus of MDR KB-8-5 cells

Catalytic properties of the framework-structured zirconium-containing phosphates in ethanol conversion

Aliphatic alcohols C1–C4 can serve as raw material for the production of essential organic products, such as olefins, aldehydes, ketones and ethers. For the develop- ment of catalysts of alcohols’ conversion, the authors considered two families of framework phosphate compounds with significant chemical, thermal and phase sta- bility: NaZr2(PO4)3 (NZP/NASICON) and Sc2(WO4)3 (SW). Variation in the com- position of zirconium-containing NZP- and SW-complex phosphates allows one to vary the number and strength of Lewis acid centers and incorporate oxidative-reduc- ing centers (such as d-transition metals) into the structure. The phosphates M0.5+xNixZr2 − x(PO4)3 (where M are Mn and Ca) were studied in the reactions of ethanol conversion. From the results of complex investigation, the compounds with M–Mn (x = 0, 0.3 and 0.5) were crystallized in the SW-type (mon- oclinic symmetry), while the phosphates with M–Ca (x = 0, 0.2 and 0.4) were char- acterized as the NZP-structured compounds (trigonal symmetry). The surface areas and pore volumes of synthesized catalysts varied, with different compositions, from 14 to 32 m2/g and 0.03 to 0.12 mL/g, respectively. From the catalytic experiments, the main direction of conversion on all the studied catalysts was ethanol dehydro- genization with acetaldehyde formation. The other conversion products—diethyl ether and ethylene—were produced with small yields. Based on the results obtained, the NZP-sample Ca0.5Zr2(PO4)3 can be considered as a selective catalyst for producing acetaldehyde at 400 °C with a yield of 55% from its theoretical amount