non-invasive reconstruction of ear inside the body using 3D printing

https://phys.org/news/2020-06-near-infrared-d-ear-body.html

 

In recent years, it has come to be used in medical applications to repair defective tissue. In such applications, ultra violoet light is used to 3-D print tissue-like material through polymerization, in which materials become denser and stick together when exposed to the light. In such efforts, surgery is required to expose the tissue that needs to be repaired. In this new effort, the researchers used near-infrared to accomplish much the same thing, but in a way that does not require surgery.

The technique involves first injecting a bioink (made of hydrogel particles and cartilage cells) into the patient. Next, a near-infrared light beam is directed at a digital micromirror device chip, which organizes the beam of light into a desired shape—the reorganized beam is then reflected down onto the patient where it penetrates the skin and collides with the bionk inside of the body. The light beam forces the bioink to form into a desired shape and to harden—the finished product resembles the cartilage that normally forms the shape of an ear. In their testing, the team used test mice with one deformed ear—the new ear was programmed using a mirror-image of the ear that was not deformed.

 

논문을 찾아보았다.

 

 

By a nanoinitiator, the commonly used biocompatible hydrogel monomers such as gelatin methacryloyl (GelMA) can be efficiently initiated for polymerization under NIR irradiation.

 

In the DNP process, a nanoinitiator, i.e., an up-conversion nanoparticle (UCNP) (24) coated with UV/blue-light photoinitiator (PI) lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) (25), was designed and called UCNP@LAP. The design was motivated by the fact that the nanoinitiator providing up-conversion UV photons emitted from UCNPs under NIR irradiation was absorbed by LAP to initiate photosensitive monomer polymerization and to avoid the UV detrimental effect on cells.

 

For photopolymerization, a commonly used light source is UV light. However, the UV light always injures cells, and its tissuepenetration ability is limited, leading to the limitation in bioprinting. Because of the good biocompatibility, blue light has attracted much attention in bioprinting in recent years. For the DNP process, it is essential to use NIR light. Because of the low-energy characteristic of NIR photon and the inadequate photon absorption of initiators, challenges remain to efficiently induce polymerization by NIR light.

With the development of up-conversion materials such as UCNPs, NIR can be converted into UV to induce photopolymerization, providing an alternative method for developing novel NIR-induced polymerizations. P

 

reference

Yuwen Chen et al. Noninvasive in vivo 3D bioprinting, Science Advances (2020). DOI: 10.1126/sciadv.aba7406