Engineered porosity for tissue-integrating, bioresorbable lifetime-based phosphorescent oxygen sensors

Area of Science:

• Biomaterials Science
• Biomedical Engineering
• Materials Chemistry

Background:

• Continuous in vivo tissue oxygen monitoring is crucial for various medical applications.
• Silk protein offers biocompatibility and tunable degradation for implantable devices.
• Developing effective optical oxygen sensors requires suitable matrix materials and sensitive chromophores.

Purpose of the Study:

• To create versatile, bioresorbable, implantable optical oxygen sensors using silk protein.
• To evaluate the biocompatibility and tissue integration of silk-based oxygen sensors.
• To demonstrate the in vivo efficacy of these sensors for monitoring tissue oxygenation.

Main Methods:

• Fabrication of silk-chromophore films and sponges using organic solvent processing.
• Incorporation of a phosphorescent palladium (II) benzoporphyrin chromophore for oxygen sensitivity.
• In vivo testing in a rodent model over several weeks, including histological assessments.

Main Results:

• Silk-based materials (films and sponges) were biocompatible and exhibited useful oxygen sensitivity (Stern-Volmer constants of 2.7-3.2 × 10^4 M^-1).
• Degradation times were tunable without significantly impacting photophysical properties.
• Sponges showed faster responses to oxygen challenges and better tissue integration compared to films.

Conclusions:

• Silk protein is a viable matrix for developing implantable optical oxygen sensors.
• Silk-chromophore sponges offer superior performance and tissue integration for in vivo oxygen monitoring.
• These sensors hold potential for continuous physiological oxygen level tracking and detecting abnormal conditions.