Polymer Colloidal Sphere-Based Hybrid Solid Immersion Lens for Optical Super-resolution Imaging.

The optical microscope is a widely used real-time investigation tool, but usually suffers from low resolution due to the Abbe diffraction limit. Herein, we design and successfully synthesize ZrO2/polymer hybrid colloidal microspheres with as high as 47.5 wt % inorganic nanoparticles by suspension polymerization of 9,9'-bis[4-(2-acryloyloxyethyloxy)phenyl]fluorene (BAEPF). Owing to the homogeneous dispersion, high density, and high refractive index of inorganic nanoparticles and deformability of polymers, the obtained ZrO2/poly(BAEPF) hybrid colloidal microspheres have a high refractive index, optical transparency, and controllable curvature and thus can be directly used as a hybrid solid immersion lens (hSIL) for the optical microscope, achieving super-resolution imaging of 50 nm and even 45 nm under a standard white light or blue light optical microscope, which is far beyond the diffraction limit for visible light optical microscopes. Our hSIL design concept and strategy demonstrate efficient, fast, and solid practical potentials for optical super-resolution imaging and may also create another application possibility for polymer colloidal spheres.

Self-assembled magnetic fluorescent polymeric micelles for magnetic resonance and optical imaging.

Stable and cytocompatible hybrid PEGylated micelles with multimodal imaging capabilities are described. The F3O4-encapsulated polymeric micelles composed of cores containing magnetic nanoparticles and polyethylene glycol (PEG) shells are synthesized by self-assembly of amphiphilic poly(HFMA-co-VBK)-g-PEG copolymers and oleic acid stabilized Fe3O4 nanoparticles. The Fe3O4 magnetic nanoparticles in the core produce T2-weighted MR imaging functionalities, whereas the small fluorescent monomer carbazole in the polymer shell introduces good fluorescent properties. The multifunctional micelles exhibit excellent paramagnetic properties with the maximum saturation magnetization of 9.61 emu/g and transverse relaxivity rate of 157.44 mM(-1) S(-1). In vivo magnetic resonance imaging (MRI) studies reveal enhanced contrast between the liver and spleen. Fluorescence spectra show characteristic emission peaks from carbazole at 350 nm and 365 nm and vivid blue fluorescence can be observed by 2-photon confocal scanning laser microscopy (CLSM). In vivo optical imaging demonstrates the unique fluorescent characteristics of the Fe3O4-encapsulated polymeric micelles in the liver and spleen and the excellent multifunctional properties suggest potential clinical use as nanocarriers in magnetic resonance imaging and optical imaging.

Fluorescent magnetic Fe3 O4 /rare Earth colloidal nanoparticles for dual-modality imaging.

Fluorescent magnetic colloidal nanoparticles (FMCNPs) are produced by a two-step, seed emulsifier-free emulsion polymerization in the presence of oleic acid and sodium undecylenate-modified Fe3 O4 nanoparticles (NPs). The Fe3 O4 /poly(St-co-GMA) nanoparticles are first synthesized as the seed and Eu(AA)3 Phen is copolymerized with the remaining St and GMA to form the fluorescent polymer shell in the second step. The uniform core-shell structured FMCNPs with a mean diameter of 120 nm exhibit superparamagnetism with saturation magnetization of 1.92 emu/g. Red luminescence from the FMCNPs is confirmed by the salient fluorescence emission peaks of europium ions at 594 and 619 nm as well as 2-photon confocal scanning laser microscopy. The in vitro cytotoxicity test conducted using the MTT assay shows good cytocompatibility and the T2 relaxivity of the FMCNPs is 353.86 mM(-1) S(-1) suggesting its potential in magnetic resonance imaging (MRI). In vivo MRI studies based on a rat model show significantly enhanced T2 -weighted images of the liver after administration and prussian blue staining of the liver tissue slice reveals accumulation of FMCNPs in the organ. The cytocompatibility, superparamagnetism, and excellent fluorescent properties of FMCNPs make them suitable for biological imaging probes in MRI and optical imaging.

Magnetic, fluorescent, and thermo-responsive Fe(3)O(4)/rare earth incorporated poly(St-NIPAM) core-shell colloidal nanoparticles in multimodal optical/magnetic resonance imaging probes.

Multifunctional colloidal nanoparticles which exhibit fluorescence, superparamagnetism, and thermosensitivity are produced by two step seed emulsifier-free emulsion polymerization in the presence of oleic acid (OA) and sodium undecylenate (NaUA) modified Fe(3)O(4) nanoparticles. In the first step, St and NIPAM polymerize the NaUA on the surface of Fe(3)O(4) nanoparticles to form Fe(3)O(4)/poly(St-NIPAM) nanoparticles which act as seeds for the polymerization of Eu(AA)(3)Phen with the remaining St and NIPAM in the second step to form an outer fluorescent layer. The core-shell composite nanoparticles show reversible dimensional changes in response to external temperature stimuli. Fluorescence spectra acquired from the composites exhibit characteristic emission peaks of Eu(3+) at 594 and 619 nm and vivid red luminescence can be observed by 2-photon confocal scanning laser microscopy (CLSM). In vitro cytotoxicity tests based on the MTT assay demonstrate good cytocompatibility and the composites also possess paramagnetic properties with a maximum saturation magnetization of 6.45 emu/g and high transverse relaxivity rates (r(2)) of 411.78 mM(-1) s(-1). In vivo magnetic resonance imaging (MRI) studies show significant liver and spleen contrast with relative signal intensity reduction of about 86% 10 min after intravenous injection of the composites. These intriguing properties suggest that these nanocarriers have large clinical potential as multimodal optical/MRI probes.