Fluorescence bioimaging in the second near-infrared spectral region (NIR-II, 900-1700 nm) can provide advantages of high spatial resolution and large penetration depth, due to low light scattering. In addition, since long-wavelength light with low photon energy is utilized as the excitation and less absorbed by the biological tissues, NIR-II fluorescence bioimaging also has low autofluorescence, as well as negligible photodamage towards biosamples. During the past few years, NIR-II fluorescence bioimaging has experienced rapid development. In this paper, we will introduce some recent research works about NIR-II fluorescence bioimaging in our research group, such as video-rate whole-body/brain/tumour angiography, organ imaging, as well as diagnosis and imaging guided treatment of tumour, on mice and monkeys.
Neuro/brain study has attracted much attention during past few years, and many optical methods have been utilized in
order to obtain accurate and complete neural information inside the brain. Relying on simultaneous absorption of two
or more near-infrared photons by a fluorophore, multiphoton microscopy can achieve deep tissue penetration and
efficient light detection noninvasively, which makes it very suitable for thick-tissue and <i>in vivo</i> bioimaging.
Nanoparticles possess many unique optical and chemical properties, such as anti-photobleaching, large multiphoton
absorption cross-section, and high stability in biological environment, which facilitates their applications in long-term
multiphoton microscopy as contrast agents. In this paper, we will introduce several typical nanoparticles (e.g. organic
dye doped polymer nanoparticles and gold nanorods) with high multiphoton fluorescence efficiency. We further
applied them in two- and three-photon <i>in vivo</i> functional brain imaging of mice, such as brain-microglia imaging, 3D
architecture reconstruction of brain blood vessel, and blood velocity measurement.
Phase modulators in surface plasmon resonance phase-differential imaging (SPR-PI) sensing systems reported so far are
sensitive to temperature fluctuations or mechanical vibrations and thus their applications are limited. In this paper, we
propose a novel prism phase modulator (PPM) to replace a traditional modulator. The PPM consists of a parallel prism, a
rotation stage and a mirror. The PPM shows great stability in our experiment, and helps achieve high detection sensitivity
in our SPR-PI system. Moreover, the cost of our PPM is much lower than that of a traditional modulator and is thus suitable
for commercialization. A polydimethylsiloxane (PDMS) microfluidic chip is fabricated to control the flow velocity and
realize parallel detection in our experiment. Measured result of glycerine solution shows that the resolution of our SPR
biosensor array is about 9.11×10<sup>-7</sup> refractive index unit (RIU). Real time monitoring of interaction between bovine IgG and anti-bovine IgG is also realized. The proposed PPM-based microfluidic SPR-PI biosensor array is promising for future
In this work, we demonstrate the bulk self-alignment of gold nanorods (GNRs) dispersed in lyotropic nematic liquid
crystals (LCs) with high optical absorption coefficient at the surface plasmon resonant wavelength. The polymer-coated
GNRs which show spontaneous long-range orientational ordering along the director of LC host exhibit long-term stability
as well as high concentration. External magnetic field and shearing allow for alignment and realignment of the orientation
of gold nanorods by changing the director of the liquid crystal matrix. This results in a switchable polarization-sensitive
surface plasmon resonance exhibiting stark differences from that of the same nanorods in isotropic fluids. The devise-scale
bulk nanoparticle alignment may enable optical metamaterial mass production and control of surface plasmon resonance of
We report multifunctional optical imaging using dye-coated gold nanorods. Three types of useful information, namely, Raman, fluorescence signals, and absorption contrast, can be obtained from a phantom experiment. These three kinds of information are detected in a nanoparticle-doped-phantom using diffuse optical imaging. Our novel nanoparticle could be used as a multimodality marker for future bioimaging applications.
Protoporphyrin IX (PpIX)-encapsulated mesoporous silica nanoparticles were synthesized, characterized, and utilized for photodynamic therapy (PDT) of cancer. Silica encapsulation is relatively transparent for activated light and can protect the PpIX against denaturation induced by the extreme bioenvironment. The mesoporous silica can also ensure that the encapsulated PpIX can be well-contacted with oxygen, stimulated, and released. PpIX-encapsulated colloidal mesoporous silica nanoparticles were uptaken by tumor cells in vitro, and the effect of photon-induced toxicity was demonstrated after comparison with some control experiments. The surface of PpIX-encapsulated silica nanoparticles can be grafted with appropriate functionalized groups and conjugated with certain biomolecules for specific targeting.