Two-photon imaging of aptamer-functionalized Copolymer/TPdye fluorescent organic dots targeted to cancer cells

• Published in: Analytica chimica acta 2020-04, Vol.1106, p.199-206
• Main Authors: Yan, Huijuan, Ren, Wu, Liu, Shuanghui, Yu, Yi
• Format: Article
• Language: English
• Subjects: Liver tissue slices; Sgc8c aptamer; Targeted imaging; Two-photon nanoprobes
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2020.02.001

Fluorescent organic dots (O-dots) recently have emerged as a new class of promising contrast reagents for two-photon fluorescence (TPF) imaging. However, most of these developed two-photon absorption (TPA) O-dots have no tumor-targeting group, which hampers their wide application for targeted tumor imaging. Herein, we fabricated Sgc8c aptamer-mediated TPA O-dots as a proof-of-concept of the sensing platform for targeted imaging in live cells or deep tissues. The O-dots composed of trans-4-[p-(N, N-diethylamino)styryl]-4’-(dimethyl amino) stilbene (DEAS) emerged as TPA organic emissive cores and encapsulation by using poly (methyl methacrylate-co-methacrylic acid) (PMMA-co-MAA) as polymeric encapsulating matrix to form DEAS/PMMA-co-MAA O-dots via a co-precipitation strategy. The obtained O-dots enabled an extremely high TPA absorption cross-section, bright two-photon fluorescence (excitation at 720 nm; emission at 412 nm and 434 nm), excellent cell-permeability and high penetration depth. Sgc8c aptamer, as a protein tyrosine kinase-7 (PTK7) receptor-targetable ligand, was further anchored on the surface of O-dots to obtain DEAS/PMMA-co-MAA@Sgc8c nanoprobes by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC)-mediated coupling reaction. Guided by Sgc8c aptamer, DEAS/PMMA-co-MAA@Sgc8c nanoprobes could be rapidly internalized into target acute lymphoblastic leukemia cells (CEM) cells with high specificity and great efficiency. It was also performed that two-photon images of TPA nanoprobes exhibited high two-photon brightness not only in target CEM cells, but also in mouse liver tissue slices even a depth of up to 210 μm. In our perception, it is highly promising that this nanoprobe provides a valuable tool for in vivo targeted imaging. [Display omitted] •A versatile and scalable strategy to aptamer-modified two-photon DEAS/PMMA-co-MAA O-dots for targeted imaging was proposed.•The DEAS/PMMA-co-MAA O-dots enabled higher two-photon brightness (45-fold enhancement).•Sgc8c acts as a tumor-specific ligand is introduced to TP nanoprobes, applying for precision targeting and imaging in cells.•This novel targeted nanoprobes was capable of two-photon imaging up to 210 μm in liver tissue slices.