Direct electrochemical biosensing in gastrointestinal fluids.

Area of Science:

• Electrochemistry
• Biosensor Technology
• Materials Science

Background:

• Direct glucose monitoring in gastrointestinal (GI) fluids is challenging due to extreme pH variations.
• Conventional biosensors degrade rapidly in acidic environments, limiting their application.
• Developing stable and edible biosensors for in-vivo sensing is a significant unmet need.

Purpose of the Study:

• To develop edible electrochemical biosensors with enhanced stability in acidic GI conditions.
• To enable direct and prolonged glucose sensing in various gastrointestinal fluid pH levels.
• To investigate the use of pH-responsive coatings for tunable sensor activation.

Main Methods:

• Fabrication of carbon-paste biosensors using edible materials (olive oil, activated charcoal).
• Incorporation of glucose oxidase (GOx) enzyme for glucose detection.
• Incubation and testing of biosensors in simulated GI fluids (pH 1.5) and comparison with screen-printed sensors.
• Application of pH-responsive enteric coatings (Eudragit® L100, Eudragit® E PO) to tune activation.

Main Results:

• Edible biosensors demonstrated remarkable resistance to extreme acidic conditions (pH 1.5) for 90 minutes.
• Conventional screen-printed biosensors showed significant performance decrease within 10 minutes under the same conditions.
• A linear glucose response (2-10 mM) was observed, with sensitivity influenced by fluid pH.
• Enteric coatings successfully tuned sensor activation in simulated gastric and intestinal fluids.

Conclusions:

• Edible electrochemical biosensors offer a stable platform for direct glucose sensing in challenging GI environments.
• The use of edible materials and protective enzyme encapsulation enhances sensor durability.
• pH-responsive coatings provide a mechanism for controlled in-vivo activation, paving the way for ingestible diagnostic devices.