Fabric Designer Makes Nanofiber Obedient Technology

As we all know, in order to produce a piece of fabric, the yarn should be formed according to the technical requirements of the fabric designer and combined according to certain rules. The nanofibers, which are only one-fifth of a millimeter in diameter, can be "obedient" like yarns, woven into fabrics as required?

How to weave these ultra-fine nanofibers like the yarns on the loom in the pattern that people expected is a problem that has plagued scientists in the field of electrospinning.

Recently, the reporter got news from the Shanghai Institute of Ceramics of the Chinese Academy of Sciences. They have been able to use advanced electrospinning technology to make the nanofibers invisible to the naked eye "obeying" and to "weave" twill according to the wishes of scientists. , rings and even Chinese knots, Scottish plaids and other patterns, and scientists have tried a variety of materials, can "woven" nanoclothes with regular patterns.

In this issue of Liang Feng's reception room, we invited the research and development personnel of this technology, Changjiang, a researcher at the Shanghai Institute of Ceramics of the Chinese Academy of Sciences, to introduce him to the research and development and application fields of this technology.

Moderator: Please tell us about what is electrospinning technology?

Chang Jiang: Electrospinning technology is a new processing method for preparing nano-scale ultrafine fibers by spraying a polymer solution (or melt) under the action of an electric field. An ordinary electrospinning preparation device is mainly composed of three parts: a high-voltage power source, a liquid storage device with a conductive spinneret, and a collector. When the instrument is working, a high pressure is applied to the spinneret, which creates an electric field between the high pressure nozzle and the low pressure collector. When the voltage is increased to a certain extent, the solution overcomes the surface tension under the action of electrostatic repulsion. And viscoelastic force, ejected from the spinneret and form a jet, the jet gradually refines during operation to the receiver, while the solvent evaporates, eventually forming an electrospun fiber on the collector.

These filaments are typically only 50 to 500 nanometers in diameter. If calculated at 50 nanometers, their thickness is only one-five thousandth of the diameter of a hair.

Moderator: Compared with the previous electrospinning technology, what is the key to making nanofibers "obedient"?

Chang Jiang: Our technology is more precisely called "controllable electrospinning technology" because we have found that the deposition and arrangement of fibers are mainly controlled by two kinds of forces, one of which is present in the spinneret. The electric field force generated by the electrostatic field between the receiver and the electrospinning fiber. When the electrospun fiber is operated toward the receiver under the electric force and close to the collector, the electrostatic charge on the surface of the fiber induces the opposite polarity of the collector surface. The electrostatic charge and the opposite charge attract each other to produce Coulomb attraction, which is another important force we have mentioned that affects fiber deposition and alignment. Therefore, in order to make the electrospun fibers "obedient" to be deposited and arranged, it is necessary to control these two important factors.

Using this principle, we designed and utilized the collection templates with different structures to control the forces affecting fiber deposition and alignment, and prepared electrospun fiber scaffolds with complex controllable patterning and braiding structures. This is a big step forward than the previous fiber orientation control technology. As the controllability of the pattern and the woven structure is further enhanced, the nanofiber becomes "obedient", which also brings a broader application prospect to the electrospinning technology.

Moderator: At present, what kind of material is this nanofiber taken from?

Changjiang: We have now tried to use a variety of materials, such as polylactic acid, polycaprolactone, polyvinylpyrrolidone, etc., can be made into electrospun fiber materials with controllable patterning and weaving structure.

Moderator: In which areas can you play its biggest role?

Chang Jiang: In detail, the application field is very extensive. For the moment, electrospun nanofibers have great application prospects in the fields of regenerative medicine and tissue engineering. For example, electrospun fibers made of polymer materials that are well compatible with tissues may be used as artificial blood vessels, artificial skin, and artificial bone materials to repair defects in such tissues. In addition, electrospun nanofibers have potential markets in electronics, catalysis, aerospace, apparel and even other industries.

Moderator: How is it applied in the medical field?

Chang Jiang: Because electrospun nanofibers are very similar in structure to natural extracellular matrix, they have good pore structure, have certain strength and stability, and are easy to process and manufacture. Therefore, it is ideal for human organ tissue repair and regeneration. One of the stent materials. It has a wide range of application value in the field of tissue engineering such as cartilage, bone, blood vessel, heart and nerve.

In general, when patients have organ and tissue damage, we generally use autologous or allogeneic methods to repair or replace wounds and defects, but this method often has the disadvantage of insufficient donor or rejection. In the near future, we may combine electrospinning technology with tissue engineering technology for the repair of human tissue damage.

Specifically, the cell scaffold is first electrospun according to the shape of the tissue or organ to be replaced or repaired by the patient, and then the corresponding seed cells are extracted from the patient and placed on the previously prepared cell scaffold for culture. Electrospinning scaffolds made of biodegradable biomaterials not only shape the new skin organs or tissues during their growth, but also provide suitable space for the biological activities of the cells and produce certain stimulating effects. It should be pointed out here that using the "controllable" technology introduced above, we can design a collection template to prepare an electrospun fiber material with a certain complex and controllable patterning structure, and to stimulate the cell to produce better by controlling the microstructure of the stent. Biological response. With the proliferation and differentiation of cells, tissues and organs are gradually formed until the defects are completely repaired, and the scaffold material is gradually degraded. As a result, the patient was reborn and the electrospinning scaffold, which acts as a growth substrate, fulfilled its mission.