Coating of Threads with Fluorescent Curli Fibers for pH Sensing

Area of Science:

• Biomaterials Science
• Textile Engineering
• Synthetic Biology

Background:

• Wearable diagnostic threads require customizable, biodegradable coatings for advanced functionality.
• Existing thread coatings often use non-biodegradable materials or irreversible dyes.
• Genetically engineered curli fibers offer a tunable platform for biosensing applications.

Purpose of the Study:

• To develop a novel, adaptable biosensing coating for threads using curli fibers.
• To demonstrate the feasibility of coating cotton threads with curli fibers for pH sensing.
• To create reusable, fluorescent threads for real-time diagnostic monitoring.

Main Methods:

• Electrostatic-mediated absorption protocol using chitosan as an intermediate layer.
• Coating anionic cotton threads with anionic curli fibers engineered with pH-sensitive fluorescent proteins (pHuji, mCitrine).
• Characterization of the coated threads' properties (hydrophobicity, stretchability) and sensing capabilities.

Main Results:

• Successfully coated cotton threads with curli fibers using a water-based, straightforward protocol.
• Demonstrated real-time pH monitoring via fluorescence changes in the protein-coated threads.
• Achieved moderately hydrophobic and stretchable coatings that remained functional for over 25 use cycles.

Conclusions:

• Curli fiber-based coatings provide a versatile and reusable platform for developing intelligent textiles.
• The electrostatic coating protocol is adaptable for various sensing targets and thread types.
• This approach advances the development of innovative wearable diagnostic devices and smart clothing.