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cryogenic 3d printing of super soft hydrogels

by:Tuowei     2019-08-26
Traditional 3D bio-printing allows the manufacture of 3D brackets for biomedical applications.
In this contribution, we propose a low temperature 3D printing method that can produce a stable 3D structure by using the liquid-solid phase change of the composite gel (CH)ink.
This is achieved by quickly cooling the ink solution below freezing point using solid carbon dioxide (CO2)
In a methanol bath.
This setting is capable of successfully creating 3D complex geometry with an average compression stiffness of O (1)kPa (0. 49u2009±u20090.
30% 04 kPa stress under compression strain)
Therefore, imitating the mechanical properties of the softest tissue in the human body (e. g. brain and lung).
The method was further verified by displaying 3D printed material matching with casting
Molded equivalents in mechanical properties and microstructure.
Preliminary biological evaluation of 3D printing materials, coated with type I collagen, PolyL-
Lai ammonia and gelatin were carried out by inoculation of human dermal fiber cells.
Cells show good adhesion and vitality on collagen
Coating 3D printing CH.
This greatly broadens the scope of application of low temperature 3D printed CH structures, from soft tissue models for surgical training and simulation to mechanical biology and tissue engineering.
In the past 30 years, 3D bio-printing has become one of the leading technologies to replicate real tissue geometry, with the possibility to simulate soft tissue microstructure.
Therefore, bio-printing is the focus of several rapidly developing research fields at present.
Recent applications include printing complete human organs to make up for the shortage of organ donors.
With the development of new soft tissue materials that can be used as printing ink, the field of bio-3D printing has grown exponentially, resulting in the extrusion of living cells suspended in printing ink.
Recently, a review was conducted with Munaz to summarize the various bio-inks used for 3D printing tissue brackets.
, Although the qualitative difference between soft tissue and hard tissue in the past did not quantify stiffness.
It has been shown that the stiffness of most human tissues is within the range of several hundred PA.
In addition, in specific cases, cell division and regeneration are promoted in tissue scaffold showing similar mechanical properties to real tissue.
Therefore, a 3D printing technology that can produce geometric and mechanical precise brackets has great potential in regenerative medicine and bionic.
This reinforces the importance of soft 3D printing.
As far as we know, there is a lack of research focused on materials that are very soft for bio-printing, and the stiffness is O (1)kPa.
One of the reasons for this is that extremely soft materials cannot bear their own weight: the printing structure is usually too soft to maintain its shape and to create more layers on it.
Some of the methods developed by other researchers are reported here. Hinton .
A free technology has been developed. form extrusion-
3D printing based on biological structure (e. g.
Branch of artery)
Use seaweed, collagen and fiberglass gel as printing ink and gel paste as a support bath.
The technology is able to achieve a resolution of about 200 µm by printing a reduced human brain using seaweed bio-ink.
However, it is reported that the hardness of seaweed ink is O (10)
Bai PA, therefore, cannot be compared with super soft tissues such as the human brain or lungs (O(1)kPa).
In another study, Lozano.
Cold junction gel 1wt % gel bio-ink modified by RGD with encapsulated cortical neuron cells.
The author was able to demonstrate the ability to print soft 3D cells
Bin Laden\'s building
However, the printing process is realized by hand.
Therefore, there is a lack of precision, and the stiffness of the material is not characterized. Adamkiewicz .
A new method for low temperature 3D printing using liquid nitrogen is introduced.
The concept behind the low temperature method is that it allows the ink in the solution state to be converted into solid state, thus allowing the use of layers to construct a stable structure in 3Dby-
No need to support the bathtub, layered.
However, the hardness of the gel ink has not been reported and the accuracy of the printing method has not been discussed.
Wang also used a low temperature method to create a 2D structure for the implant.
The base plate cooled by coolant flow is used to manufacture the low temperature stage.
Similarly, the mechanical properties of the printed structure are not reported.
Therefore, this paper presents the manufacture of mechanically accurate 3D printed composite gel by using a novel printing device based on low temperature theory, which simulates the stiffness of super soft tissue.
Solid carbon dioxide (dry ice)
And using ethanol thermal bath, the cycle stage is realized, which is a safer alternative than liquid nitrogen.
The ink used in this work is poly (vinyl)alcohol (PVA)
And feitagel, created by Lebing. and Forte .
Imitating soft tissue, such as the brain, has a stiffness of O (1)kPa.
Another advantage of this new 3D printing technology compared to traditional casting molding methods is the possibility of producing hollow structures of super soft gels.
The interconnected holes make it impossible to extract soft hollow structures from the mold using traditional casting molding techniques.
The purpose of this study is as follows :(i)
Through the unrestricted compression test, mechanical evidence was provided to show that the 3D printed material simulates the real brain tissue and provides the same response as the casting material ,(ii)
In order to demonstrate the capability of this printing technique by implementing a hollow 3D printing structure, its continuity in layers was also evaluated using a scanning electron microscope (SEM)analysis, and (iii)
Evaluate the viability of cells in direct contact with printed materials to confirm the potential for future studies in mechanical biology.
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