Biocompatible astaxanthin as novel contrast agent for biomedical imaging

Area of Science:

• Biomedical Imaging
• Materials Science
• Oncology

Background:

• Photoacoustic imaging (PAI) offers high resolution and sensitivity for cancer staging.
• Limited endogenous contrast in PAI necessitates exogenous contrast agents for tumor targeting.

Purpose of the Study:

• To evaluate the feasibility of astaxanthin, a marine-derived compound, as a biocompatible contrast agent for PAI.
• To quantitatively assess PA signal variations with astaxanthin concentration in phantoms and ex vivo tissues.

Main Methods:

• Utilized a Q-switched Nd:YAG laser (532 nm) and a 5 MHz ultrasound transducer.
• Tested astaxanthin concentrations (up to 5 mg/ml) in silicon tubing phantoms and ex vivo bladder tissues.
• Acquired and analyzed PA signals to determine response to astaxanthin.

Main Results:

• PA signal amplitude increased linearly with astaxanthin concentration, with a detection threshold of 0.31 mg/ml.
• Astaxanthin-injected tissues showed up to a 16-fold increase in PA signals compared to saline.
• PAI enabled imaging and 3D volume quantification of astaxanthin distribution.

Conclusions:

• Astaxanthin demonstrates potential as a biocompatible contrast agent for PAI.
• Further research is needed to validate selective tumor targeting for PAI-assisted bladder cancer detection.