Biomimetic materials based on hydroxyapatite patterns for studying extracellular cell communication

The study of cellular ion channels forms a basic understanding of healthy organ functioning and the body as a whole; however, the native role of signal transmission through ion channels between cells remains unclear. The success of the signal transmission investigation depends on the methods and materials used. Therefore, it is necessary to develop a new approach and system for studying detecting cell–cell communication. In this work, we suggest the system of hydroxyapatite patterns demonstrating piezoresponse in conjunction with fiber-based biosensors for detection of electrical signaling in cellular communities. Our system does not disrupt the integrity of cell membrane. The cells are located on self-assembled hydroxyapatite patterns forming the tissue patterns and communicating via spatially propagating waves of calcium, sodium, and potassium ions. These waves result from positive feedback caused by the activation of Ca2+ channels. The fiber-based ion-selective microelectrodes fixed above the patterns are used to detect the sodium, potassium, calcium ion currents in the extracellular space. We use norepinephrine to activate the Ca2+ channels result in intracellular Ca2+ release between the cell communities on different patterns. This system could be perspective as an efficient platform to lab-on-a-chip study as well as fundamental understanding of cellular communication during regeneration

The Identification of Cu–O–C Bond in Cu/MWCNTs Hybrid Nanocomposite by XPS and NEXAFS Spectroscopy

The results of the research of a composite based on multi-walled carbon nanotubes (MWCNTs) decorated with CuO/Cu2O/Cu nanoparticles deposited by the cupric formate pyrolysis are discussed. The study used a complementary set of methods, including scanning and transmission electron microscopy, X-ray diffractometry, Raman, and ultrasoft X-ray spectroscopy. The investigation results show the good adhesion between the copper nanoparticles coating and the MWCNT surface through the oxygen atom bridge formation between the carbon atoms of the MWCNT outer graphene layer and the oxygen atoms of CuO and Cu2O oxides. The formation of the Cu–O–C bond between the coating layer and the outer nanotube surface is clearly confirmed by the results of the O 1s near edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) of the Cu/MWCNTs nanocomposite. The XPS measurements were performed using a laboratory spectrometer with sample charge compensation, and the NEXAFS studies were carried out using the synchrotron radiation of the Russian–German dipole beamline at BESSY-II (Berlin, Germany) and the NanoPES station at the Kurchatov Center for Synchrotron Radiation and Nanotechnology (Moscow, Russia)