Lipid nanocapsules as in vivo oxygen sensors using magnetic resonance imaging

NMR diffusometry: A new perspective for nanomedicine exploration

“…However, it could be sometimes tricky to convert signal profile into concentration profile and calibration steps or relaxation time quantification could be valuable. Another way to track nanomedicines is to acquire a specific resonance frequency signal associated with the nanomedicine, different from the water one, such as fat for 1 H [30] or fluorine-19 [31] for heteronuclei. In this case, the signal is directly proportional to the concentration of nuclei but lower sensitivity or reduced spatial resolution is often observed compared to labeling strategies.…”

Engineering Intelligent Nanosystems for Enhanced Medical Imaging

“…Low tissue oxygen levels play a role in other conditions as well, including cardiac ischemia and wound healing. Therefore, imaging hypoxia is important for medical prognostics and therapy monitoring, and responsive imaging nanosystems have been developed for MRI, [226][227][228] optical imaging, [203,[229][230][231] and photoacoustic imaging. [232] Moreover, as tumor oxygen levels affect the efficiency of photodynamic therapy, oxygen mapping may be used to guide the procedure.…”

“…[ 230 ] Most MRI is based on 1 H proton relaxation in water molecules and molecular oxygen may function as paramagnetic T1‐shortening contrast agent in MRI. [ 228 ] However, due to the high water‐to‐oxygen ratio, T1 change by oxygen is limited. In contrast, the solubility of oxygen is six times higher in lipids than in water, turning MRI into a suitable tool for sensing oxygen levels.…”

“…Indeed, oxygenation changes after a carbogen challenge could be detected in mice. [ 228 ] Furthermore, hypoxia is one of the characteristics of inflammatory bowel disease (IBD). Zhou et al developed a mesoporous silica nanoparticles loaded with an squarylium fluorescent dye and a BHQ2 quencher to image this characteristic (Figure 10E).…”