pH-Dependent Cellular Internalization of Paramagnetic Nanoparticle.

A hallmark of the tumor microenvironment in malignant tumor is extracellular acidosis, which can be exploited for targeted delivery of drugs and imaging agents. A pH sensitive paramagnetic nanoaparticle (NP) is developed by incorporating GdDOTA-4AmP MRI contrast agent and pHLIP (pH Low Insertion Peptide) into the surface of a G5-PAMAM dendrimer. pHLIP showed pH-selective insertion and folding into cell membranes, but only in acidic conditions.

A nano-sized PARACEST-fluorescence imaging contrast agent facilitates and validates in vivo CEST MRI detection of glioma.

Aim: The authors have investigated the usefulness of in vivo chemical exchange saturation transfer MRI for detecting gliomas using a dual-modality imaging contrast agent.

Materials & Methods: A paramagnetic chemical exchange saturation transfer MRI contrast agent, Eu-1,4,7,10-tetraazacclododecane-1,4,7,10-tetraacetic acid-Gly(4) and a fluorescent agent, DyLight 680, were conjugated to a generation 5 polyamidoamine dendrimer to create the dual-modality, nano-sized imaging contrast agent.

Results: The agent was detected with in vivo chemical exchange saturation transfer MRI in an U87 glioma model.