Bright and stable near-infrared Pluronic–silica nanoparticles as contrast agents for in vivo optical imaging

Abstract

Near-infrared (NIR) fluorescent nanostructured materials have emerged as novel contrast agents for non-invasive bioimaging. Here we report a class of polymer-silica nanoparticles doped with a NIR fluorescent dye prepared through a facile one-pot strategy. Hydrophobic NIR fluorescent dyes such as IR 780 iodide could be easily encapsulated into the micellar core by self-assembly of amphiphilic triblock copolymer Pluronic F127. When subsequently adding silane in aqueous solution, nanoparticles with a cross-linked core and a hydrophilic PEG shell were formed. The structure of the as-obtained nanoparticles was confirmed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The nanoparticles exhibited a well-defined spherical structure with a mean diameter of approximately 30 nm, and excellent monodispersity and stability in aqueous solution. In addition, the photo-stability of IR 780 was significantly improved by encapsulation into the nanoparticles. In vitro MTT assay with cell lines HEK293 and A431 demonstrated that the IR 780 loaded nanoparticles (termed as IR780@NPs) were biocompatible. In vivo sentinel lymph node imaging revealed that the fluorescent intensity and retention time of the IR780@NPs were clearly superior to its constituent free dye, making it amenable to in vivo bioimaging. Further in vivo tumor imaging indicated that IR780@NPs have a longer retention time and much higher accumulation on the tumor site compared to free dye after intravenous administration. Overall this hydrophilic NIR fluorescent contrast agent exhibits excellent photophysical characteristics and low cytotoxicity, and holds a strong promise for a variety of applications including bioimaging and therapy.

Tailoring the morphology of AIEgen fluorescent nanoparticles for optimal cellular uptake and imaging efficacy

“… 17 – 19 Over the past few decades various fluorescent materials have been developed, such as fluorescent proteins, 20 – 22 quantum dots, 23 , 24 carbon dots, 25 – 27 organic dyes, 28 – 30 and fluorescent organic nanoparticles (FONPs). 18 , 31 – 37 Among these, FONPs remain relatively unexplored for biomedical application, which is mainly due to two limitations: (1) their inherent fluorescence quenching, 38 , 39 which is common for most organic fluorophores during their aggregation in aqueous media; and (2) their uncontrolled morphology and cellular behavior. 40 – 42 Fortunately, since the concept of aggregation-induced emission (AIE) was originally reported by Tang et al , 43 a large number of new AIE materials 32 , 33 , 44 – 50 have been explored for their various applications.…”

Minimizing ATP depletion by oxygen scavengers for single-molecule fluorescence imaging in live cells

“…To lessen photobleaching, experimenters have developed encapsulated dyes that are protected from oxygen molecules in solution (27). Quantum dots (28,29) and polymer dots (30) overcome this issue as well.…”

Review of In Vitro Toxicity of Nanoparticles and Nanorods—Part 2

“…was found that an intracellular increase of Zn 2+ precedes cell death, indicating the intracellular dissolution of the ZnO NWs after uptake [112][113][114][115][116][117][118][119][120].…”