Search

It is of great significance to study the brain structure and function in deep-tissue for neuroscience research and bio-medical applications because of the urgent demand for precise theranostics. Three-photon fluorescence microscopic (3PFM) bioimaging excited by the light in near-infrared IIb (NIR-IIb, 1,500–1,700 nm) spectral region is one of the most promising imaging techniques with the advantages of high spatial resolution, large imaging depth, and reduced scattering. Herein, a type of NIR-IIb light excitable deep-red emissive semiconducting polymer dots (P-dots) with bright 3PF and large three-photon absorption cross-section (σ3) at 1,550 nm was prepared. Then the P-dots were functionalized with polystyrene polymer polystyrene graft ethylene oxide functionalized with carboxyl groups (PS-PEG-COOH) and modified with NH2-poly(ethylene glycol) (PEG) to synthesis photochemically stable and biocompatible P-dots nanoparticles (NPs). Further the P-dots NPs were utilized for in vivo 3PFM bioimaging of cerebral vasculature with and without the brain skull under 1,550 nm femtosecond (fs) laser excitation. In vivo 3PFM bioimaging of the mice cerebral vasculature at various vertical depths was obtained. Moreover, a vivid three-dimensional structure of the mice vascular architecture beneath the skull was reconstructed. At the depth of 350 µm beneath the brain skull, 3.8 µm blood vessels could still be clearly recognized. NIR-IIb excitable P-dots assisted 3PFM bioimaging has great potential in accurate deep tissue bioimaging. [ABSTRACT FROM AUTHOR]

Near-infrared (NIR) fluorescence imaging is an important imaging technology in deep-tissue biomedical imaging and related researches, due to the low absorption and scattering of NIR excitation and/or emission in biological tissues. Laser scanning confocal microscopy (LSCM) plays a significant role in the family of fluorescence microscopy. Due to the introduction of pinhole, it can provide images with optical sectioning, high signal-to-noise ratio and better spatial resolution. In this study, in order to combine the advantages of these two techniques, we set up a fluorescence microscopic imaging system, which can be named as NIR-LSCM. The system was based on a commercially available confocal microscope, utilizing a NIR laser for excitation and a NIR sensitive detector for signal collection. In addition, NIR fluorescent nanoparticles (NPs) were prepared, and utilized for fluorescence imaging of the ear and brain of living mice based on the NIR-LSCM system. The structure of blood vessels at certain depth could be visualized clearly, because of the high-resolution and large-depth imaging capability of NIR-LSCM. [ABSTRACT FROM AUTHOR]

Aggregation-induced emission (AIE) luminogen displays bright fluorescence and has photobleaching resistance in its aggregation state. It is an ideal fluorescent contrast agent for bioimaging. Multiphoton microscopy is an important tool for bioimaging since it possesses the ability to penetrate deep into biological tissues. Herein, we used AIE luminogen together with multiphoton microscopy for long-term imaging of zebrafish. A typical AIE luminogen, 2,3-bis(4-(phenyl(4- (1,2,2-triphenylvinyl) phenyl)amino)phenyl) fumaronitrile (TPE-TPA-FN or TTF), was encapsulated with 1,2-distearoyl-sn-glycero-3-phosphoethanola-mine-N-[methoxy(polyethylene glycol)-2000] (DSPE-mPEG2000) to form nanodots that exhibited bright three-photon fluorescence under 1,560 nm-femtosecond (fs) laser excitation. The TTF-nanodots were chemically stable in a wide range of pH values and showed no in vivo toxicity in zebrafish according to a series of biological tests. The TTF-nanodots were microinjected into zebrafish embryos, and the different growth stages of the labeled embryos were monitored with a three-photon fluorescence microscope. TTF-nanodots could be traced inside the zebrafish body for as long as 120 hours. In addition, the TTF-nanodots were utilized to target the blood vessel of zebrafish, and three-photon fluorescence angiogram was performed. More importantly, these nanodots were highly resistant to photobleaching under 1,560 nm-fs excitation, allowing long-term imaging of zebrafish. [ABSTRACT FROM AUTHOR]

Multiphoton microscopy and nanoparticle-assisted photodynamic therapy are two important areas in biophotonics research. In this paper, we combined these two technologies together. Photosensitizer (HPPH) doped colloidal mesoporous silica nanoparticles were synthesized and systematically characterized. Based on a confocal microscope equipped with a 1560 nm femtosecond laser, we showed: (1) direct three-photon luminescence from HPPH doped nanoparticles, which were uptaken by tumor cells, and (2) cytotoxicity towards tumor cells by HPPH under three-photon excitation. Nanoparticle-assisted three-photon photodynamic therapy can be a promising technology for disease diagnosis and in vivo/clinical therapy. [ABSTRACT FROM AUTHOR]