Luminescent difluoroboron β-diketonate poly(lactic acid) (BF2bdkPLA) materials serve as biological imaging agents. In this study, dye structures were modified to achieve emission colors that span the visible region with potential for multiplexing applications. Four dyes with varying π-conjugation (phenyl, naphthyl) and donor groups (−OMe, −NMe2) were coupled to PLLA-PEG block copolymers (∼11 kDa) by a postpolymerization Mitsunobu reaction. The resulting dye-polymer conjugates were fabricated as nanoparticles (∼55 nm diameter) to produce nanomaterials with a range of emission colors (420-640 nm). For increased stability, dye-PLLA-PEG conjugates were also blended with dye-free PDLA-PEG to form stereocomplex nanoparticles of smaller size (∼45 nm diameter). The decreased dye loading in the stereoblocks blue-shifted the emission, generating a broader range of fluorescence colors (410-620 nm). Tumor accumulation was confirmed in a murine model through biodistribution studies with a red emitting dimethyl amino-substituted dye-polymer analogue. The synthesis, optical properties, oxygen-sensing capabilities, and stability of these block copolymer nanoparticles are presented.
Bibliographical noteFunding Information:
We thank the National Institutes of Health (R01 CA167250) and UVA Cancer Center (P30 CA44579) for support of this work. We thank Corbion Purac for the generous donation of the D- and L-lactide monomers. We gratefully acknowledge the Beckman Foundation for a Beckman Scholarship to C.K. The Harrison Foundation is also acknowledged for an award to C.K. and M.D. We thank Prof. Kelly Dryden, at the UVA Molecular Electron Microscopy Core, which is supported by the UVA School of Medicine and the NIH (G20-RR31199). We thank Tristan Butler for helpful discussions. We also utilized the Duke Optical Molecular Imaging and Analysis shared resource at Duke, which is supported by the Duke Cancer Institute and Duke School of Medicine.
© 2017 American Chemical Society.