Congying Yuan

Conflicts of Interest The authors declare no conflicts of interest. References 1 and , “Bioprinting Toward Organ Fabrication: Challenges and Future Trends,” IEEE Transactions on Biomedical Engineering 60, no. 3 (2013): 691–699. 2, , and , “A Dual-Sensitive Hydrogel Based on Poly(Lactide-co-Glycolide)-Polyethylene Glycol-Poly(Lactide-co-Glycolide) Block Copolymers for 3D Printing,” International Journal of Bioprinting 7, no. 3 (2021): 389.

1. Introduction Among many amino acids, tryptophan is one of the amino acids that make up human proteins, and abnormal metabolism of this amino acid can lead to anxiety, dysphagia, hallucinations, and delusions [1,2,3]. In addition, acetone is an important raw material for organic synthesis, and long-term exposure will cause irreversible damage to liver organs or nerves and cause inflammation [4].