Injectable, thermosensitive, fast gelation, bioeliminable, and oxygen sensitive hydrogels.

Area of Science:

• Biomaterials Science
• Medical Imaging
• Polymer Chemistry

Background:

• Pathological conditions decrease tissue oxygen, causing cell death and damage.
• Accurate, long-term oxygen monitoring is crucial for assessing treatment efficacy.
• Existing electron paramagnetic resonance (EPR) probes lack injectability, bioeliminability, and stable retention.

Purpose of the Study:

• To develop injectable and bioeliminable hydrogel-based EPR probes for sustained in vivo oxygen detection.
• To create probes with fast gelation, slow degradation, and high oxygen sensitivity for minimally invasive monitoring.
• To address the limitations of current EPR probes regarding toxicity and retention.

Main Methods:

• Synthesized hydrogel probes using N-Isopropylacrylamide (NIPAAm), HEMA, DBA, and TAM radical.
• Evaluated probe gelation rate, weight loss, and oxygen sensitivity in vitro.
• Assessed probe stability, bioeliminability, and oxygen sensitivity after in vivo implantation.

Main Results:

• Developed injectable hydrogel probes with a ~10s gelation rate for high tissue retention.
• Demonstrated slow weight loss and sustained EPR signal intensity over extended periods.
• Confirmed high oxygen sensitivity and bioeliminability after 4 weeks of in vivo implantation.
• Polymeric nature of probes mitigated toxicity concerns associated with small molecule probes.

Conclusions:

• Injectable, bioeliminable hydrogel-based EPR probes show promise for minimally invasive, long-term in vivo oxygen monitoring.
• The developed probes offer a stable, sensitive, and safe platform for assessing therapeutic interventions targeting tissue oxygen levels.
• These probes have potential for clinical translation in managing conditions associated with hypoxia.