A combined imaging and phototherapy technique could help guide surgeons removing chemotherapy-resistant tumors and kill any cancer cells the surgeons miss. Researchers at Oregon State University said their technique prevented cancer recurrence in the ovaries of laboratory mice 25 days after treatment. The mice showed no apparent side effects or weight loss following the procedure. According to the researchers, the technique is simpler and involves few components than other proposed theranostic approaches, making it a good candidate for clinical translation. A new imaging and phototherapy technique uses nanoparticle dendrimers to carry a drug that sets the stage for improved cancer surgery and phototherapy. Courtesy of Oregon State University. “For many cancers, surgery is a first choice of treatment,” said professor Dr. Oleh Taratula. “In coming years we may have a tool to make that surgery more precise, effective and thorough than it’s been before.” The technique involves nanoparticles containing the compound silicon naphthalocyanine, which fluoresces when exposed to near-infrared light. In addition to highlighting cancerous tissue, the drug also generates cancer-killing reactive oxygen species when illuminated. The silicon naphthalocyanine was irradiated at 785 nm with a laser power density starting at 0.3 W/cm2. At power densities up to 1.3 W/cm2, the drug also gave off heat, showing it could be useful for photothermal therapy as well. Meanwhile, the compound continued fluorescing during the phototherapeutic procedure and was not photobleached. On its own, silicon naphthalocyanine isn’t water-soluble and tends to clump up inside the body, limiting its effectiveness. To get around this problem, the researchers encapsulated it with water-soluble polymer nanoparticles called dendrimers whose physical characteristics allow them to slip easily into tumor blood vessels while leaving healthy tissue alone. The researchers hope to next test their technique on live dogs with malignant tumors before progressing to human trials. Funding came from the Oregon State University College of Pharmacy, the Medical Research Foundation of Oregon and the PhRMA Foundation. The research was published in Nanoscale (doi: 10.1039/C4NR06050D). For more information, visit www.oregonstate.edu.