(4fi) Engineering Biopolymer Crystallinity in Microneedles for Improved Food Monitoring System

Understanding the hierarchical assembly of structural proteins, including amorphous to crystalline phase transit, is critical for adequately utilizing their functionality for engineering purposes. Among many structural proteins, researchers have extensively explored silk fibroin for the generation of various advanced material formats via control of polymorphisms (amorphous to crystalline transition) and forms (sol-gel-solid transition). Beyond traditional utilization of silk fibroins’ mechanical properties, recent studies have focused on the non-toxic and edible nature of silk fibroins extracted from Bombyx mori silkworm cocoons for food contact applications. In this study, we present a silk-based microneedle device for food bacteria detection. The water-annealing post-process increases fibroin crystallinity and creates a 3-dimensional porous structure stable upon contact with wet food samples. The microneedles extracted internal food fluid into the pores and transported the fluid to a colorimetric sensor on the backside of the needle array via the capillary action. Within a day of injection, we identified E. coli contamination in fish fillets by color changes of the polydiacetylene-based sensor. We were able to distinguish this response by E. coli contamination from common food spoilage. We also showed that the microneedle sensor could pierce commercial food packaging, implying a successful adaptation of the technology downstream in conventional food supply chains. Therefore, this study provides insights into food quality monitoring and global food safety by minimizing food loss and waste.

Research Interests

Dr. Doyoon Kim (Ph.D. in Energy, Environmental, & Chemical Engineering, 2018) is interested in nanoscale reactions at biological interfaces in aqueous environments. For example, he is excited to study the nucleation of nanocrystals on structural biopolymers and the hierarchical assembly of biopolymers in the presence of nanocrystal precursor molecules. Furthermore, inspired by the interfacial phenomena observed in nature, he aims to design nano/organic composite materials to provide engineering solutions to our society's sustainability challenges caused by climate change and other anthropogenic activities. In his previous studies, Dr. Kim investigated the nucleation of calcium phosphate mineralization in organic templates for biomedical engineering (bone regeneration) and environmental engineering (phosphorous removal). Currently, Dr. Kim is working on silk-based advanced biopolymers for sustainable food and agriculture system.

Teaching Interests

Based on his expertise, Dr. Doyoon Kim will be a suitable faculty candidate for teaching courses such as Aquatic Chemistry, Environmental Nanochemistry. Also, he is interested in teaching fundamental chemical engineering courses for undergraduate, such as Kinetics and Reaction Engineering, Transport Processes, Mathematical Methods in Engineering, and Micro and Nanofabrication. In addition, he is enthusiastic about developing new courses based on his research expertise, such as Advanced Materials for Sustainable Environment and Chemical Reactions in Environmental Remediation.