Researchers at the Indian Institute of Science (IISc) in Bengaluru have pioneered a novel, minimally invasive imaging agent designed to improve early tumor detection. Published in JACS Au on June 12, 2025, the study introduces GPc, a synthetic molecule tailored for photoacoustic tomography (PAT)—a hybrid imaging technique harnessing sound waves generated when light-excited agents rapidly expand.
GPc stands for a tetra‑glucose conjugated zinc‑phthalocyanine. It combines:
A zinc‑phthalocyanine core, a near‑infrared (NIR)–absorbing chromophore ideal for PAT.
Four glucose units attached to improve uptake and water solubility.
When injected into the body, GPc targets metabolically active tumor cells—which have a higher glucose demand—akin to how PET scans use FDG tracers.
A NIR laser pulses through tissue.
GPc molecules absorb the light and heat up briefly.
This rapid heating causes them to expand and emit ultrasound waves.
The ultrasound data is used to reconstruct 3D images of tumors with high contrast.
Advantages include:
Lower cost than PET or MRI,
No ionizing radiation exposure,
Better performance for detecting superficial tumors such as skin or breast lesions.
Cellular uptake: Using seahorse metabolic assays, researchers confirmed GPc enters tumor cells but is not metabolized via GLUT1 transporters—unlike FDG—making it a stable imaging agent.
Selective localization: Lab studies using mice carrying tumors showed GPc accumulation in tumor cores, especially in regions with low oxygen supply (hypoxia).
Optical & pharmacological properties: The glucose units improve solubility and bioavailability without invoking rapid metabolic degradation.
| Feature | PET (FDG) | MRI | GPc?PAT (new) |
|---|---|---|---|
| Cost | High (radioactive) | High | Relatively low |
| Safety | Radiation exposure | No ionizing radiation | No radiation |
| Invasiveness | Radioactive tracers | Contrast agents | Biocompatible small molecule |
| Spatial resolution | Moderate | High | High for superficial tumours |
| Metabolic targeting | Yes | Partial (diffusion, blood flow) | Yes |
Superficial tumor detection: Ideal for breast, thyroid, skin lesions where NIR penetration is sufficient.
Repeat imaging: Zero radiation enhances patient safety in serial monitoring.
Clinical development: While encouraging, the molecule requires extensive preclinical safety and pharmacokinetic validation before moving to human trials.
Complementary use: GPc-PAT could be integrated with existing imaging platforms, offering a low-cost, bedside-friendly diagnostic alternative.
You are able to use a more cost-effective technique, cheaper than both PET and MRI to get the same information.Sanhita Sinharay, Assistant Professor at Department of Bioengineering, IISc
This breakthrough highlights a significant advancement in cost-effective, radiation-free tumor imaging, potentially revolutionizing early diagnosis—especially in regions where PET and MRI are prohibitively expensive or scarce.
(Input from various sources)
(Rehash/Sakshi Thakar//MSM)