Nanobubble Facilitated Optoporation and Photoacoustic Imaging of BT-474 Breast Cancer Cells

Permeabilization of the cell membrane can be achieved through techniques such as sonoporation and microinjection. An alternative method is optoporation that uses tightly focused laser pulses typically from femtosecond lasers. Localized damage/modification of the plasma membrane has been shown using light absorbing nanoparticles heated with short laser pulses. In this work, we use targeted nanobubbles stained with Sudan Black B for purposes of enhancing optoporation without using femtosecond lasers as well as a contrast agent for photoacoustic microscopy. Nanobubbles were targeted with antibody Herceptin and added to each petri dish before being incubated for 4 hours before photoacoustic imaging. Fluorescence microscopy was used to confirm presence of the nanobubbles using DiO lipid stain. The photoacoustic microscope is equipped with a 400MHz transducer and 532nm laser focused through a 10x objective. The focal spots of laser and transducer were co-aligned and a portion of the leaser beam was directed to a joulemeter for energy measurement. Propidium Iodide was used to detect poration where uptake was not seen in healthy cells but uptake was seen as early as 7 minutes in nanobubble loaded cells. PA signals were detected from cells loaded with NBs and were not from the control group.