Progress in Biomedical Applications Of Femtosecond Laser Processing Technology At The University Of Science And Technology Of China (USTC)

The purpose of tissue engineering is to construct tissues and organs with physiological functions for repairing diseases and defects in the human body. Only skin, cartilage and bone tissue engineering products have been used in clinical applications because tissues constructed in vitro lack a compatible blood supply system. Scientists have successfully printed artificial hearts, livers, lungs, kidneys and other tissues and organs, but the printing of artificial microvascular networks, especially capillary networks (tube diameter of 6 to 9 μm), has always been a difficult problem and bottleneck in tissue engineering.
Recently, Associate Prof. Jiawen Li's group in the Micro and Nano Engineering Laboratory, School of Engineering Science, University of Science and Technology of China (USTC) has proposed a femtosecond laser dynamic holographic processing method suitable for the efficient construction of 3D capillary scaffolds for generating 3D capillary networks. The work was published as "Rapid Construction of 3D Biomimetic Capillary Networks with Complex Morphology Using Dynamic Holographic Processing The work was published in Advanced Functional Materials under the title of "Rapid Construction of 3D Biomimetic Capillary Networks with Complex Morphology Using Dynamic Holographic Processing" and was selected as the cover paper of the journal, and the related technology was authorized by a patent.
Femtosecond laser two-photon polymerization has nanoscale processing resolution and three-dimensional fabrication capability, but the traditional processing strategy to print microvascular networks is inefficient. Based on the previous work, the group proposes a local phase modulation method based on the ring-shaped Bessel beam to generate a ring-shaped notched light field, and utilizes the fast-changing notched ring light to expose inside the photoresist to realize the efficient processing of complex shape bifurcated microtubule networks and bionic porous microtubules, and the processing speed is over 30 times higher than that of the traditional point-by-point processing method. The group used the porous microtubule network as a scaffold to guide endothelial cells to grow against the wall, realizing the construction of complex microvascular networks with definable morphology, and this work will provide a platform for research work in the fields of tissue engineering, drug screening and vascular physiology. Bowen Song, a master's student, Shengying Fan, a doctoral student, and Chaowei Wang, a postdoctoral fellow, are the co-first authors of the paper, and Jiawen Li is the corresponding author.
In recent years, Li's group has been actively exploring the application of femtosecond laser processing technology in the biomedical field, and has made progress in the preparation method of micro-nano robots. Micro-nano robots show great application prospects in the biomedical field. In order to realize the large-volume preparation and controllable transportation of micro-robots in complex environments, the group proposes an efficient preparation method of environment-responsive micro-helical robots based on rotationally dynamic holographic light field, which can process thousands of hydrogel micro-helical robots within 0.5h. The robot realizes the intelligent adaptive deformation of its own morphology under the regulation of pH, and then a variety of motion modes occur under the drive of the magnetic field, realizing the fixed-point transportation of drugs. In order to solve the problem of low magnetic content of micro-helical robots, driving force is small, it is difficult to overcome the influence of the environmental flow rate, the group proposes a two-photon polymerization forming and sintering method based on the process of preparing a pure nickel helical micro-robot, the helical robots magnetic content of about 90 wt%, in the low-intensity rotating magnetic field enhances the magnetic torque, the maximum speed of up to 12.5 body lengths per second, and can propel the weight of the object than its own 200 times, and in the The magnetic torque is enhanced by a low-strength rotating magnetic field.
In addition, Jiawen Li's group explored the effects of micro-nano structures on neuronal growth behavior based on femtosecond laser two-photon processing. In collaboration with Prof. Guo-Qiang Bi of the Department of Life Sciences and Medicine and Associate Prof. Weiping Ding of the School of Information Science and Technology, they prepared arrays of patterned micropillars with different spacing and heights using femtosecond two-photon technology, and found that neuronal axons tended to grow on isometric micropillars, and that they were able to guide the directional growth of neurons and the formation of neural circuits by constructing the micropillar rows. Inspired by axonal myelination, the joint group simulated axonal myelination by designing and preparing microtubule structures with different diameters, wall thicknesses and lengths, and found that the microtubule structures were able to accelerate the growth rate of neuronal axons (more than 10 times). In addition, the joint group magnetically sputtered a magnetic thin film of nickel and a biocompatible thin film of titanium on the surface of the microtubules, which can be used for the precise connection of neurons under the manipulation of an external magnetic field to form a specific biological neural circuit. The micro-nanostructures are capable of directional and accelerated neuronal growth, which will provide methods and ideas for directional connection of isolated nerve clusters, neural network construction, and rapid repair of nerve damage.