A. Yu. Gerasimenko

A study of preparation techniques and properties of bulk nanocomposites based on aqueous albumin dispersion

Bulk nanocomposites prepared from an aqueous albumin dispersion with carbon nanotubes by removing the liquid component from the dispersion have been investigated. The composites were obtained by thermostating and exposure to LED and IR diode laser radiation. The nanocomposites obtained under laser irradiation retain their shape and properties for several years, in contrast to the composites fabricated in different ways (which decompose into small fragments immediately after preparation). The low density of the composites under study (∼1200 kg/m3), which is close to the density of water, is due to their high porosity. The hardness of stable nanocomposites (∼300 MPa) was found to be at the same level as the hardness of polymethylmethacrylate, aluminum, and iron and close to the hardness of human bone tissue. The cluster quasiordering of the inner structure of nanocomposites revealed by atomic force microscopy indicates the possibility of forming a bulk nanotube framework in them, which can be caused by the effect of the electric field of laser radiation and ensure their stability and hardness. The presence of a framework in nanocomposites provides conditions for self-assembly of biological tissues and makes it possible to apply laser-prepared nanocomposites as a component of surgical implants.

Investigation of nonlinear characteristics of intensity limiters of high-power laser radiation

The problem of determining nonlinear-optical characteristics of working substances of limiters of high-power laser radiation is analyzed. A new method of simultaneous calculation of the beam-waist radius and nonlinear absorption coefficient from the Z-scan data is proposed. The value of nonlinear optical characteristics of ZnSe, porphyrin-graphene (Graphene-TPP), fullerene-graphene (Graphene-60), polyethylene oxide containing multilayer carbon nanotubes (PEO/MWNT), along with polymethine dyes PD-792 and PD-7098 and dicyanomethylene-pyran dyes DCM-627 and DCM-684, are obtained. Different working substances are compared for the first time under the same conditions by plotting output characteristics of laser-radiation limiters. The change of the laser-pulse shape after propagation through the limiters with different working substances is demonstrated.

The method of laser forming of nanocarbon biocompatible coatings for implants

The work is devoted to laser method of biocompatible coatings forming to create implants of the human body ligaments. Coating is a carbon nanotubes scaffold formed in the water-protein dispersion by the electric field of the laser radiation. Study has been conducted on the structure and properties of carbon nanotubes coatings and proliferative activity of biological cells on its surface.

Nonlinear threshold effect in the Z-scan method of characterizing limiters for high-intensity laser light

A threshold model is described which permits one to determine the properties of limiters for high-powered laser light. It takes into account the threshold characteristics of the nonlinear optical interaction between the laser beam and the limiter working material. The traditional non-threshold model is a particular case of the threshold model when the limiting threshold is zero. The nonlinear characteristics of carbon nanotubes in liquid and solid media are obtained from experimental Z-scan data. Specifically, the nonlinear threshold effect was observed for aqueous dispersions of nanotubes, but not for nanotubes in solid polymethylmethacrylate. The threshold model fits the experimental Z-scan data better than the non-threshold model. Output characteristics were obtained that integrally describe the nonlinear properties of the optical limiters.

Laser Technology of Designing Nanocomposite Implants of the Knee Ligaments

We describe a laser method for constructing a biocompatible implant of the knee ligaments based on synthetic-braided fiber structure of polyethylene terephthalate (PET) coated with a nanocomposite coating. A coating based on albumin aqueous dispersion of carbon nanotubes (CNTs) was applied to the synthetic fibers using ultrasound and then formed by laser evaporation of the aqueous dispersion component. The structure of the nanocomposite implants was studied by optical and atomic force microscopy. Composite implant based on single-walled CNTs (SWCNTs) contains pores with a diameter of 10–20 nm, and based on multi-walled CNTs (MWCNTs)—40–60 nm. We conducted in vitro studies of proliferative activity of human fibroblast cells (HFb) during their colonization on the surface of the implant and into the space between synthetic fibers. The highest value of the HFb proliferation was observed on the implant based on MWCNTs with a large pore size and amounted to 55.435 pcs., in contrast to the implant based on SWCNTs (54.931 pcs.) and control one (54.715 pcs.), as shown by fluorescence microscopy and MTT test. A histological study of the interaction of the nanocomposite implant implanted into rabbit knee joint with bone canal was carried out. The bone germination in the implantation area at 2, 4 and 8 weeks after surgery was shown.

Study of laser radiation detection by matrix sensor based on carbon nanotubes array

Presently laser radiation is widely used in the variety of fields. This indicates the necessity of the control the intensity of laser radiation. In this case use the sensors - devices that convert laser radiation into an electronic signal. Using carbon nanotubes (CNTs) in sensor design is perspective direction, which can lead to of creating devices with impressive parameters.

Development of the device prototype based on the semiconductor–carbon nanotubes structure for optical radiation detection and study of its parameters

A light-receiving device prototype based on the semiconductor–carbon nanotubes (CNTs) structure consisting of 16 cellular structured sensitive elements grown on the same substrate is developed. The topology of sensitive cells represents holes through metallization and insulator layers to the semiconductor from which the CNT array grows to the top metallization layer. The device prototype parameters are determined as follows: the effective wavelength range is within 400–1100 nm, the operational speed is no longer than 30 μs, the coefficients of peak sensitivity reached at wavelengths of 640 and 950 nm are 197 and 193 μA/W, respectively.

Laser nanosolder characteristics effect on tensile strength and structure of biotissue seam weld

This work is concerned with studying the technique of dissected tissue laser welding using specific facility and nanosolder. The technique perfomance was studied on the hog stomach mucous membrane samples. Laser solder compositions that allow maximal durability of the tissue welding seam were revealed and its 3D structure was studied using x-ray microtomography. Biocompatibility of the laser nanosolder was proved.

Increasing the conductivity of the carbon nanotube-based layers by laser radiation

The 5-50 μm-thick layers of a nanomaterial consisting of acrylic paint and multilayer carbon nanotubes (~3 mass.%) are investigated. It is shown that laser radiation and heat treatment enhance the conductivity of the layers by a few orders of magnitude. The layers remain stable in water for over 200 h and exhibit a conductivity of ~ (100-1000) S/m, which make them promising for application in biomedical electrodes and wearable electronics.

The Radiation Detector with Sensitive Elements on the Base of Array of Multi-walled Carbon Nanotubes

The detector of the visible and infrared radiation on a multi-walled carbon nanotubes has been studied. The sensitive element was represented by a two-electron square-shaped matrix with linear dimension of 2 mm containing numerous cells (2 μm diameter, 2.3 μm depth, 6 μm distance between cells) in which arrays of multi-walled carbon nanotubes are synthesized. All measurements have been realized at the room temperature. Maximum photo-emf of ~100 mV was reached in the visible and short-range IR of 500–1500 nm and minimum photo-emf of ~0.1 mV in range of 1500–8000 nm. Maximum photosensitivity ~12.2 mA/W was realized at 1100 nm emission wavelength and its capacity of 50 μW. Speed capability was equal to ~30 μs and efficiency factor of energy transformation of infrared radiation into electric—0.13 %. It is expected that the optimization of the parameters of the sensitive element and the mode of operating temperature, characteristics of IR radiation detector on the arrays of multi-walled nanotubes will significantly improve. In particular, the operating range of wavelength, photoconductivity, speed capability and efficiency of energy transformation of IR radiation into electric will increase.