Japanese research group is trying to synthesize new bio-nylon by pepsin

Currently available traditional nylons such as nylon 6, nylon 66 and nylon 11 are not degradable
.
On the other hand, bionylon derived from itaconic acid shows higher performance than conventional nylon and is degradable in soil, but its degradability by digestive enzymes has not been demonstrated
.

To address these issues, a research team from the Japan Institute of Advanced Science and Technology (JAIST) is investigating the use of pepsin to synthesize a new bio-nylon
.
Led by Professor Tatsuo Kaneko and Dr Mohammad Asif Ali, their latest research is published in Advanced Sustainable Systems in April 2021
.

In this study, the synthesis of bionylon is based on a chemically developed novel chiral dicarboxylic acid derived from renewable itaconic acid and amino acids (D- or L-leucine)
.
In addition, bionylon was prepared by melt polycondensation of hexamethylenediamine with chiral-interacting heterocyclic diacid monomers, as shown:

The chiral interaction arises from the diastereomeric mixture of the racemic pyrrolidone ring and the chiral amino acid of leucine
.
Therefore, the polyamide shows a glass transition temperature of about 117°C and a melting temperature of about 213°C, which is higher than the conventional bio-nylon 11 (Tg of about 57°C)
.
These bionylons also showed high Young's modulus E and mechanical strength σ, 2.
2–3.
8 GPa and 86–108 MPa, respectively
.

The material can be used as an alternative to traditional nylon for fishing nets, ropes, parachutes and packaging
.
Bionylon including peptide linkages showed enzymatic degradation with pepsin, a digestive enzyme found in the mammalian stomach
.
Pepsin degradation can be linked to biodegradation in the stomach of marine mammals
.
This innovative molecular design of high-performance nylon through controlled chirality could contribute to a sustainable, carbon-negative industry and energy savings through weight reduction
.