Covalently Functionalized Click Alginate Cryogels Enable Non-Invasive Near-Infrared Sensing of Gastric pH

Covalently functionalized click alginate cryogels enable non-invasive near-infrared sensing that resolves gastric pH 2.0 from pH 5.0 in rats transabdominally.

• Why it matters: Gastric acidity is linked to mucosal injury in reflux disease, peptic ulcer, and gastritis, yet is rarely measured, leaving acid-suppressive therapy titrated mainly by symptoms.
• What they did: The team used bioorthogonal tetrazine–norbornene click crosslinks to covalently anchor a pH-sensitive reporter (IRDye 680RD) in acid and protease-rich conditions, then tested dye release, stability, and imaging in rats.
• The result: Dye release stayed below 1.5% in simulated gastric and intestinal fluids, the pH response remained active after nine months, and photoacoustic imaging showed pH-dependent contrast for deeper-tissue detection.

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