We describe a method to measure pH in tumor tissues noninvasively by a chemically responsive polyacrylic acid-based injectable hydrogel sensor. Extracellular pH in the tumor is particularly promising because it plays a key role in cancer metastasis and chemotherapy resistance. Measuring in situ chemical pH is currently very challenging, requiring expensive and specialized imaging techniques. However, X ray imaging technique is a ubiquitous, inexpensive, and routinely used imaging modality used to detect tumors and assess growth. We developed the first injectable chemical sensor which can be read by X ray imaging technique to understand the local tissue pathophysiology and monitor treatments. The hydrogel pH sensor contains a radiodense tantalum bead within it so that the pH-dependent hydrogel length can be measured via X-ray imaging. To be able to inject the sensor into a tumor and prevent direct contact, the hydrogel is placed in a porous sleeve. The entire sensor fits inside a biopsy marker needle which will be used to both collect a tissue specimen and inject the sensor into the tumor tissue. Preliminary results showed a dynamic range between pH 4–8 with a 0.07 pH unit precision. A repeatable response to pH cycling was observed between pH 6.5 to 7.5 in bovine serum which is the pH most relevant to tumor acidosis. An animal tumor model will be used to study the effects of the tumor microenvironment on the performance of the sensor, in vivo.

X-ray visualized acidosis hydrogel sensor to measure tumor pH

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.