Optical Density Changes of Aqueous Dispersion for Biological Materials and Carbon Nanotubes with Action Gradient Magnetic Field

Abstract

Objective. Composite nanomaterials containing matrices of biological materials and filler made of carbon nanotubes (CNTs) are promising. They can be used in various implants, for example, in bone or cartilage tissues, and their aqueous suspensions, the so-called biological solders, are suitable for laser welding of biological tissues [1]. Since CNTs contain catalytic ferromagnetic or so-called superparamagnetic nanoparticles, they can be used for non-invasive monitoring of nanotubes. Thus, carbon nanotubes can be regarded as a kind of magnetic particles (MP). In our experiment, we investigated the change in optical transmission under the action of the magnetic field of aqueous dispersions containing biological materials and single-walled CNTs (SWCNTs). Materials and methods. Aqueous composite nanomaterials contained a matrix of either bovine serum albumin (BSA) or microcrystalline cellulose (MCC) and a filler of SWCNT. BSA/SWCNT and SWCNT aqueous dispersions were prepared in the same way as described in [1]. They consisted of: 15 wt.% BSA and 0.01 wt.% SWCNT; 3 wt.% MCC and 0.01 wt.% SWCNT and 0.01 wt.% SWCNT, respectively. The relative optical density T of aqueous dispersions was measured in the optical range lambda = 200–1100 nm. For each variance, measurements of the T data were repeated three times, which made it possible to check the stable repetition of the obtained T(lambda) curves. To record the T(lambda) dependences, the variance was prepared as follows. Two identical cuvettes were filled. A neodymium magnet was attached to one cell, which created a magnetic field gradient of the order of ~ 1 T/m. The dispersion was retained in the cells for up to 72 h. After the end of the exposure of the dispersion in a magnetic field, optical measurements were carried out on a spectrophotometer. Results. At lambda = 550 nm, the values of T were compared for various aqueous dispersions. It turned out that the values of T are approximately by ∼ 10–15% lower in dispersions exposed to the action of a magnetic field, compared to the dispersion on which a magnetic field was not affected. The effect of the magnetic field on T is especially noticeable at lambda ≤ 400 nm. For example, in the variances BSA/SWCNT and MCC/SWCNT, the changes in T values reached ~25%. Conclusion. Confocal microscopy showed that, under the influence of a magnetic field, SWCNTs aggregate to form linear chains on which light is strongly scattered and decreases T. It is proposed to use this effect to determine the size of SWCNT aggregates in aqueous dispersions of the composite nanomaterials under study, and also consider a non-invasive method for their registration (similar MP) using magnetic field sensors with a low threshold of magnetic sensitivity ≤ 10-9 T.

Keywords: optical density, bovine serum albumin; microcrystalline cellulose; single-walled carbon nanotubes; magnetic field gradient

Acknowledgements: This study was supported by the Ministry of Science and Higher Education of the Russian Federation No. 075-03-2020-216 from 27.12.2019.

References
[1] Ichkitidze L.P., Gerasimenko A.Yu., Podgaetsky V.M., Selishchev S.V. Materials Physics and Mechanics, 2018, 37(2), 153.

Speaker

Levan Ichkitidze
Institute of Biomedical Systems of National Research University of Electronic Technology “MIET”, Institute for Bionic Technologies and Engineering of I.M. Sechenov First Moscow State Medical University
Russia

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