A low-cost biosensor for glucose analysis was designed, fabricated and characterized. It was fabricated by using a DLPdirect light processing, 3D printed technique. The operation principle for the electro-optic device is based on the total internal reflection. The photosensitive resin is considered that is doped with nanoparticles such as quantum dots and carbon nanotubes as a waveguide. By using DLP 3D printing technique the device was fabricated. The operation principle was based on the optical phase shift. The entire structure of the device features a Mach-Zehnder Interferometer (MZI) that was numerically analyzed in a commercial software featuring finite element. The biosensor works in the transmission scheme. Mach-Zehnder interferometer is composed of a waveguide that encompasses the resin doped with nanodots that linked both input and output signals. In contrast, one arm is kept isolated and the other arm exposed to the medium in order to obtain the phase change at the MZI output. A laser-diode of 980 nm was considered as the source. The optical array features a single-mode optic fiber and a bidirectional coupler. While tested, several glucose concentrations (from 0% to 3%) were provided in order to determine the relationship between the glucose concentration and the output signal in order to increase the sensitivity. The future possibility of the aforementioned structure describes the use of several materials for biological-related applications are also discussed.
The technology of cell 3D scaffolds laser fabrication is developed. 3D scaffolds are designed to repair osteochondral defects, which are poorly restored during the organism’s life. The technology involves the use of an installation, the laser beam of which moves along a liquid nanomaterial and evaporates it layer by layer. Liquid nanomaterial consists of the water-protein (collagen, albumin) suspension with carbon nanoparticles (single-walled carbon nanotubes). During laser irradiation, the temperature in the region of nanotubes defects increases and nanotubes are combined into the scaffold. The main component of installation is a continuous laser operating at wavelengh of 810 nm. The laser beam moves along 3 coordinates, which makes it possible to obtain samples of the required geometric shape. The internal and surface structure of the samples at the micro- and nanoscale levels were studied using the X-ray microtomography and scanning electron microscopy. In vitro studies of cell growth during 48 and 72 hours demonstrated the ability of cell 3D scaffolds to support the proliferation of osteoblasts and chondroblasts. Using fluorescence and atomic force microscopy, it was found that the growth and development of cells on a sample with a larger concentration of nanotubes occurred faster compared to samples with a smaller concentration of nanotubes.
In this work, tissue-engineered structures based on a matrix of protein conjugates, chitosan and carbon nanotubes were prepared and studied. Bovine serum albumin (BSA), bovine collagen (BС) were used. Two types of single-walled carbon nanotubes (SWCNTs) were used to form a strong internal scaffold in a protein-chitosan matrix under the action of laser radiation. Tissue-engineered structures were created by means of layered deposition and laser evaporation of the initial aqueous dispersion from SWCNT, BSA, BC and chitosan succinate. As sources of laser radiation, a continuous diode laser with a wavelength of 810 nm and a pulsed fiber laser with a wavelength of 1064 nm and frequency of 80 kHz were used. Studies of tissue-engineered structures were carried out using vibrational spectroscopy methods (IR and Raman). The changes in the frequencies and intensities of the corresponding absorption bands and Raman lines of the amide group oscillations were analyzed. IR spectra of tissue-engineered structures demonstrated a high degree of binding of organic (protein, chitosan) and inorganic (SWCNT) components. The structure and defectiveness of the carbon nanotube scaffold were investigated in the Raman spectra.
The study of structural properties of nanocomposites, based on different types of single walled carbon nanotubes (SWCNTs) and proteins (albumin, collagen), was carried out. The binding of protein molecules to the carbon component was described by Raman spectroscopy. Complex analysis of the structure and microporosity of nanocomposites was performed by the X-ray microtomography. The nanoporosity study was carried out using the low-temperature nitrogen porosimetry method. Samples based on SWCNTs with smaller size had the most homogeneity. With an increase in the concentration from 0.01 to 0.1 %, the mean micropore size increased from 45 to 93 μm, porosity in general increased from 16 to 28 %. The percentage of open pores was the same for all samples and was 0.02. As it was shown by Raman spectroscopy the protein component in nanocomposites has undergone irreversible denaturation and can act as a biocompatible binder and serve as a source of amino acids for biological tissues. These nanocomposites are bioresorbable and can be used to repair cartilage and bone tissue. This is especially important in the treatment of diseases of hyaline cartilage and subchondral bone.
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.
Applicability of porous anodic alumina formed in selenic acid based electrolyte as the matrix for formation and Raman characterization of nanomaterials is investigated. For that, Raman spectra of nanostructured CdS layers deposited on top of porous alumina matrices are obtained. These spectra were compared with the ones, registered for the composites prepared using the commonly used matrix formed in oxalic acid solution. It is shown that application of porous alumina matrix formed in selenic acid electrolyte afford to detect the peaks corresponding to the CdS layers even at small amounts of CdS. It happens due to the absence of luminescence background in such matrix, which exists in matrices produced in organic acid electrolytes, for example, in oxalic acid.
Creation of effective means of protection from laser radiation of high power requires the development of optical materials (working substance), with their transparence being decreased sharply above a certain critical value of the laser intensity due to the appearance of non-linear optical properties (limiting threshold). Based on the threshold model, the working substance of the optical limiter was characterized. Experimental data of z-scan with open aperture are used to determine the nonlinear optical parameters of solutions of dimeric phthalocyanine complexes of Mg and Zn of J-type in tetrahydrofuran (THF) and thin films of their conjugates with single-walled carbon nanotubes (SWCNTs). The output characteristic (output (peak) fluence vs input (peak) fluence), that describes the basic properties of optical limiters, was obtained with the fixed location of the optical limiter. Dimeric phthalocyanine complexes were found to have low limiting threshold ~ 2 MW·cm-2 and high value of the nonlinear absorption coefficient ~ 330 and 370 cm GW-1, respectively. Conjugates of these dimeric phthalocyanines with SWCNTs have been produced for the improving of the limiting parameters and increasing of the optical nonlinearity. Size of J-type dimeric phthalocyanine complexes of Mg and Zn were determined by the scanning electron microscopy (SEM). The atomic force microscopy (AFM) allowed to determine the dimensions of nanotubes. The structure parameters, such as diameter and defects as well as the strength of aggregates were estimated with the Raman spectroscopy. For our experiments, the lens with a focal length of 20 cm was used. As the laser radiation source, the Nd:YAG laser was used to generate pulses of 16 ns duration at a wavelength of 532 nm with the linearly polarized laser beam in the horizontal plane and a shape closed to Gaussian type.
The technology of production of matrix photoreceivers based on carbon nanotubes (CNTs) consisting of 16 sensitive elements was developed. Working wavelength range, performance and sensitivity were studied.
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