IISc's GPc: A Revolutionary Radiation-Free Imaging Method for Tumors

Scientists at the Indian Institute of Science (IISc) have developed a groundbreaking imaging molecule, GPc, which promises to revolutionize cancer diagnosis by providing a radiation-free alternative to traditional imaging methods such as Positron Emission Tomography (PET) and Magnetic Resonance Imaging (MRI). This innovative technique employs Photoacoustic (PA) Tomography to create high-contrast three-dimensional images of tumors, particularly those located near the body’s surface. The findings were published in the Journal of the American Chemical Society (JACS Au) on June 15, 2025.

The development of GPc responds to the critical challenges associated with PET scans, which are currently the gold standard for tumor detection. PET scans utilize radioactive glucose tracers, such as 18F-FDG, to highlight areas of increased metabolic activity, indicating the presence of tumors. However, these procedures are not only costly but also expose patients to radiation risks, particularly concerning for individuals requiring multiple scans for ongoing cancer monitoring.

According to Dr. Sanhita Sinharay, Assistant Professor at the Department of Bioengineering at IISc and the corresponding author of the study, “You are able to use a more cost-effective technique, cheaper than both PET and MRI, and get the same information.” The innovative PA imaging technique employed by GPc circumvents radiation exposure by utilizing near-infrared (NIR) light to excite specially designed contrast molecules that subsequently emit sound waves. These sound waves are then detected to construct detailed images of the tumors.

Historically, PA imaging has been limited to natural chromophores present in the body, such as hemoglobin. The breakthrough achieved by the IISc research team involves the creation of GPc, a biocompatible molecule designed to enhance sensitivity and contrast in imaging. GPc consists of four glucose units conjugated to a zinc-phthalocyanine scaffold, which significantly improves its water solubility and cellular uptake, allowing it to reach tumor sites effectively.

Pooja Patkulkar, a PhD student at IISc and the first author of the study, elaborated on the significance of GPc, stating, “We wanted to see whether the molecule we made was being taken up by the glucose transporters, and what its fate was after uptake.” The research team confirmed through biochemical tests, including a seahorse assay, that GPc is not metabolized and does not compete with glucose, solidifying its potential as a safe diagnostic tool.

The implications of this innovation for cancer patients, particularly in low-resource settings, are profound. The advantages of GPc include: - **No Radiation Exposure:** Unlike PET scans, GPc does not involve any radiation, significantly reducing health risks for patients. - **Lower Costs:** The affordability of PA imaging could make tumor diagnosis more accessible, especially in countries where PET technology is limited, such as India. - **Potential for Repeat Scans:** The absence of radiation allows for the possibility of performing regular imaging without the associated health risks. - **Enhanced Imaging of Superficial Tumors:** GPc can provide improved imaging for tumors that are located close to the skin, such as those in the breast, skin, or lymph nodes.

As noted in the IISc's statement, “The use of such molecules can greatly help visualize tumor sites with high metabolic activity non-invasively… providing similar functionality at a lower cost.”

Looking ahead, while initial laboratory studies have demonstrated promising results, further research and clinical trials will be essential to fully validate GPc's effectiveness in human patients across various tumor types. If successful, this innovative imaging technique could significantly transform the landscape of non-invasive cancer diagnostics, particularly in regions where access to advanced imaging technology remains a challenge.

In conclusion, the development of GPc by IISc marks a pivotal advancement in medical imaging technology, offering a safer, more affordable, and accessible method for diagnosing cancer, and potentially reshaping the future of oncological care in resource-limited settings.