Electrospinning Combined With 3D Printing: From Imagination To Reality

In recent years, news reports about 3D printing are often seen: hospitals use 3D printing to customize an organ model suitable for patient size, and a creative team creates a thin paper like LED lamp. Ge Corp has pointed out that in 50 years, 3D printing technology will be able to successfully print an aero engine. 3D printing technology has been considered to be one of the core technologies of the third industrial revolution.

　　 3D printing is a kind of rapid prototyping technology. It is a rapid prototyping technology based on digital model files, which can be constructed by means of engineering plastics or metal powder and so on. The technology can simplify product manufacturing process, shorten product development cycle, improve efficiency and reduce costs, and can be widely used in medical, cultural, defense, aerospace, automobile and metal manufacturing industries. It is considered to be a significant technological achievement in the manufacturing field in the past 20 years.

According to the principle of printing technology and the different materials, 3D printing technology can be divided into laser cladding forming technology (LCF), fused deposition rapid prototyping (FDM), selective laser sintering (SLS), stereolithography (SLA) and three-dimensional printing (3DP). However, these traditional 3D printing technology can only print to the millimeter level. The surface of the printed products is somewhat rough and can not achieve the best effect. In addition, some biological products are sintered or fused by 3D printing, resulting in low bioactivity and limited application. Therefore, researchers begin to take a deeper look at the application and technology. So the electrospinning technology that we are familiar with has begun to enter people's imagination.

In the electrospinning industry, more and more attention has been paid to 3D printing. Researchers began to think about how to integrate electrospinning and 3D printing with the same importance, thus changing the defects of 3D printing in size. It also expanded the two-dimensional structure of electrostatic spinning from pure membrane, line and belt to three-dimensional structure. Thus 3D printing combined with electrospinning began to slowly come out of the researcher's imagination and come into reality, and some technologies began to be applied.

3D bio printing technology is one of the most cutting-edge and most popular areas in 3D printing technology. Because 3D printing is personalized, it can be widely used in biomedicine, including cell printing, tissue engineering scaffolds, implants, dentistry and so on. Although biological 3D printing technology has the advantages of other traditional techniques in the manufacture of biodegradable three-dimensional structure, at present, several mature 3D printing processes, such as SLS, SLA and 3DP, often use the aid of high temperature sintering, spray bonding agent and other auxiliary forming hand segments, which will lead to the destruction of biological activity of materials, which largely limits the application of these methods in tissue engineering, biomedicine and other fields. Therefore, biological incremental extrusion technology and electrospinning technology based on 3D printing principle have been put forward and attracted extensive attention from scholars at home and abroad.

3D printing cartilage

The team of Dietmar W. Hutmacher of Queensland University of Technology, Australia, published Reinforcement of hydrogels using three-dimensionally printed printed in Nature Communications. It introduced in detail how to use biocompatible materials to repair human tissues more effectively, especially articular cartilage. Because the cartilage has certain mechanical strength and flexibility, researchers have tested a new synthetic material of hydrogel and microfiber scaffolds to achieve this requirement. The researchers used a new 3D printing technology, melt electrospinning writing technology, which is a processing method for making charged polymer melt in the electrostatic field to form polymer jet microfluidic fibers. This method helps to provide room for cell growth, and also has certain help to the mechanical rigidity of cells. Finally, the printed structure can not only achieve natural healing, but also promote the growth of new tissues. The 3D printing technology based on electrostatic spinning opens the door for biomedical researchers.

　　 3D printed absorbable stent

"Physical Chemistry Chemical Physics" (Phys.Chem.Chem.Phys., 2015, 17, 2996) published the article "Characterization and preparation preparation", "the Characterization and preparation preparation", "the Characterization and preparation preparation," the paper introduces the natural polymer nanofibers composed of artificial blood vessels transplanted into the human body to promote the recovery of damaged blood vessels. However, biocompatible materials such as chitosan, which are used in electrospinning nanofibers, lack good mechanical properties. Therefore, the researchers' design and manufacture are divided into two steps. The first step is to prepare chitosan and PCL blend nanofiber scaffolds by electrospinning technology, then use 3D rapid prototyping technology to coat PCL chains, and finally produce artificial blood vessels. The vascular prosthesis fabricated by this method has excellent mechanical properties, and this method can be used for vascular reconstruction.

　　 The rapid manufacturing engineering center of Shanghai Univer has made breakthroughs in biological 3D printing. In the June 2015 issue of "Journal of Southeast University" published by Liu Yuanyuan, Shanghai Univer, entitled "Composite bioabsorbable vascular stents via 3D bio-printing 3D", a new stent was designed for vascular stenosis treatment. In view of the lack of equipment and technology in the preparation of bioabsorbable stent, a new method of preparation of composite bioabsorbable stent with biological 3D printing and electrospinning is proposed. First, the inner layer of the scaffold was prepared by 3D printing with PPDO material. Then the mixed solution of chitosan and PVA was prepared, and the outer layer of the stent was prepared by electrospinning. The mechanical properties tests showed that the scaffold fabricated by 3D printing and electrospinning was better than the conventional scaffold only. The cell test on the scaffold showed that the cells had good adhesion and proliferation on the scaffolds. The proposed composite forming process and method provided a good idea for the subsequent construction of the controllable drug carrier.

　　 3D print clothing

At present, printing with 3D printing technology is generally hard and can not be used for close clothing. Conventional electrospinning usually uses high voltage power supply, and the distance between Taylor cone and receiving platform is large. After spinning, it becomes a ball, so it is difficult to control its orderly stacking. The team from San Francisco made the platform into a hanger shape, and launched the world's first 3D electric loom Electroloom, which can automatically produce polyester cotton blended clothing. The principle of this 3D printer is similar to that of electrostatic spinning. The template is designed by CAD software. After putting the designed template into the printing bin, the mixed fabric liquid solution is molded under the guidance of the electromagnetic field according to the template. This process is called "electrospinning". Then, the printer evenly mixed the nanofibers and made them into a seamless fabric.

　　 3D printing building

Kim, a professor at Seoul National University in South Korea, published an article entitled "Toward Nanoscale Three-Dimensional Printing: Nanowalls Built of Electrospun Nanofibers" in "Langmuir". They demonstrated the independent nano walls and other nano scale objects which can be constructed by the use of the accelerator printing. A new method of electrodepositing polymer nanofibers in an accurate and repetitive way to generate the specified objects was introduced.

Electrospinning is a relatively simple way to make polymer nanotubes. Nanoscale fiber flow is very confusing. It is very difficult to control single fiber. In their recent research work, it was found that the use of a thin metal electrode line can make the nanoscale fiber flow relatively orderly. Using this line, the polymer nanotubes can be stacked to form a wall structure. Research shows that the electrostatic interaction between fiber and metal wire can be used to balance the tensioning degree of polymer fibers, and the length of a nano wall can be controlled by controlling the translation of the base. The research team said that the new 3D printing technology can be applied to the development and application of biological scaffolds, nanofiltration and nano electrodes.

　　 Electrospinning has played a huge role in the field of tissue engineering scaffolds and energy storage. However, rapid prototyping technology is needed in the construction of various shapes. Therefore, the application of 3D printing technology will undoubtedly enrich the application space of electrospinning. In turn, 3D printing technology has not been able to get a big breakthrough in the problem of size refinement.