Preparation and Biofunctionalization of Multicolor Conjugated Polymer Nanoparticles for Imaging and Detection of Tumor Cells

Abstract

enced by changing the choice, amount and ratio within each CPN. [ 7,26 ] Additionally, as single multicolor CPNs can be tuned to match the different excitation sources of commercial optical instruments, such as fl uorescence spectrometers, fl uorescence microscopes, and in fl ow cytometry.In this work, we describe the design and synthesis of four conjugated polymers with blue, green, yellow and red emissions, and used them to prepare carboxyl functionalized CPNs by a co-precipitation method based on hydrophobic interactions between the conjugated polymers and poly(styreneco -maleic anhydride) (PSMA). [ 6,27 ] The carboxyl functionalized CPNs can also be prepared by co-precipitation of four conjugated polymers with PSMA, which show multicolor emissions by under single excitation wavelength. CPNs were modifi ed with primary antibody to obtain CPNs-antibody conjugates. In comparison to single antibody recognition, higher specifi city for tumor cells detection was achieved by binding two CPNs labeled with different antibodies to a single tumor cell. Finally, we show that the multicolor CPNs can match different excitation sources of fl uorescence microscopy and fl ow cytometry to achieve straightforward cell imaging and detection.Four π-conjugated polymers (P1 ∼ P4) were obtained by Suzuki cross-coupling polymerization of monomers 1 -4 with monomer 5 [ 17,28 ] in yields of 15∼48% ( Scheme 1 a). Absorption and fl uorescence characteristics were determined in CHCl 3 and show that each polymer spans a different region of the visible spectrum (Table S1). Compared with the corresponding monomers, the absorption spectra of P1∼P4 ( Figure S1) not only have characteristic absorptions of monomers but also exhibit new combination absorptions with the increase of aromatic heterocyclic units. In these polymers, the absorptions in shorter wavelength region originate from the fl uorene units, and the longer absorptions lie in the signal aromatic heterocyclic unit or cooperative actions of different monomers. The emission spectra show maxima for P1, P2, P3 and P4 are 422, 500, 540 and 670 nm, respectively. Emission quantum yields (QY) vary depending on the electron acceptor unit in the polymer backbones (3 ∼ 78%). Upon excitation at 360 nm, the shorter wavelength-emissive polymers were anticipated to act as the donor for longer wavelength-emissive ones (acceptors), through interchain multi-step FRET. Thus, by varying the mixing ratio of the polymers, multicolor emission can be regulated through FRET among the four polymers under one excitation wavelength. In order to achieve bioconjugation, CPNs are required to provide surface functional groups (such as -COOH, -NH 2 , -N 3 , -C≡CH, etc.) for subsequent modifi cation. Herein, such CPNs with carboxyl groups on the surface were prepared by a modifi ed co-precipitation method [ 6,27 ] based Conjugated polymer nanoparticles (CPNs) combine the properties of conjugated polymers (CPs) and nanoparticles and defi ne a new class of promising fl uorescence materials that are being integrated in...

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