Metal Nanoparticles in Laser Bioprinting

Laser bioprinting is a promising method for applications in biotechnology, tissue engineering, and regenerative medicine. It is based on a microdroplet transfer from a donor slide induced by laser pulse heating of a thin metal absorption film covered with a layer of hydrogel containing living cells (bioink). Due to the presence of the metal absorption layer, some debris in the form of metal nanoparticles is printed together with bioink microdroplets. In this article, experimental investigations of the amount of metal nanoparticles formed during the laser bioprinting process and transported in bioink microdroplets are performed. As metal absorption layers, Ti films with the thickness in the range of 25–400 nm, produced by magnetron spattering, were applied. Dependences of the volume of bioink microdroplets and the amount of Ti nanoparticles within them on the laser pulse fluence were obtained. It has been experimentally found that practically all nanoparticles remain in the hydrogel layer on the donor slide during bioprinting, with only a small fraction of them transferred within the microdroplet (0.5% to 2.5%). These results are very important for applications of laser bioprinting since the transferred metal nanoparticles can potentially affect living systems. The good news is that the amount of such nanoparticles is very low to produce any negative effect on the printed cells.

Transient Dynamic Response of a Semi-infinite Elastic Permeable Solid with Cylindrical Hole Subject to Laser Pulse Heating Under Different Theories of Generalized Thermoelasticity

Our current work is related to the study of vibrations induced by laser beams on the behalf of distinct theories of magneto-thermo-elastic diffusion problem in a semi-infinitely long, conducting isotropic elastic solid with cylindrical hole in a uniform magnetic field acting on the surface of the cylindrical hole of the solid in the direction of the axis of the cylindrical hole. The temporal scheme of laser beam is considered as non-Gaussian and is acted on the surface of the cylindrical hole. The problem is solved with the help of Laplace transform domain and finally illustrated graphically. Note: This article will be very useful in material science specially, in powder metallurgy during sintering, hot pressing, wire and rods annealing are examined from a unified physical point of view, in different branches of engineering physics like plasma physics, nuclear physics, geophysics and related topics and also in oil industry (Lyashenko and Hryhorova (2014), Long and Heng-Wei (2018), Fryxell and Aitken (1969), Nowinski (1978), Legros et al. (1998), Galliero et al. (2019) etc.).

Editorial

Since 2007 High Temperatures-High Pressures regularly publishes invited articles selected from presentations given during the International Workshop on Subsecond Thermophysics (IWSSTP). These well-established workshops take place every three years at various locations. They are aimed to provide a forum for exchange of knowledge, experience and ideas on the latest developments and trends in the field of thermophysical property measurement. A special focus is given to measurements under extreme conditions, at high temperatures or pressures, and/or on the study of the behavior of matter under conditions close by or far away from thermodynamic equilibrium. Timescales range from milliseconds to picoseconds, necessitating rapid resistive or inductive (volume) heating, laser pulse heating, levitation techniques on ground and under microgravity, as well as other recently developed fast investigation techniques. The 12th IWSSTP, which this present special issue is devoted to, took place from June, 3rd to June, 6th, 2019. It was a pleasure and a great privilege for me and the Institute of Materials Physics in Space of the German Aerospace Center (DLR), Cologne to organize the current event and welcome the international community as hosts. This time, the 12th IWSSTP coincided with the 50th anniversary since the launch of High Temperatures – High Pressures which gave reason to celebrate.