Photodynamic therapy (PDT) is a treatment that involves a photosensitizing agent, which produce reactive oxygen species (ROS) upon exposure to a specific wavelength of light, resulting in cell death. 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) derivatives are beneficial as photosensitizers due to their high extinction coefficient, high photostability, and insensitivity to solvent conditions. BODIPY derivatives are functionalized on hyaluronic acid polymer chain that is known to target CD44 overexpressed cancer cell lines. Degree of substitution (DS) of BODIPY-functionalized hyaluronic acid polymer was determined by ultraviolet (UV) absorption calibration of the BODIPY moiety. Singlet oxygen generation by BODIPY-functionalized hyaluronic acid was measured by monitoring UV decrease of 1,3-diphenylisobenzofuran (DPBF) that is known to selectively react with singlet oxygen. Conjugation extension through alpha position of BODIPY shows red-shifted absorbance, which allows use of longer wavelength of light, resulting deeper penetration of the light in tissue. In addition, it is observed that halogen-functionalization on BODIPY core reduces fluorescence due to heavy atom effect, which implies high possibility of phosphorescence that could contribute to singlet oxygen generation. These results are consistent with the result in UV monitoring of DPBF. The results in preliminary cytotoxicity study demonstrate that BODIPY-functionalized hyaluronic acid is potentially useful as a photosensitizer for PDT application.

BODIPY-functionalized hyaluronic acid as a photosensitizer for photodynamic therapy

251st National Meeting (2016)

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