Four-Photon Excited Amplified Emission

1
Four-Photon Excited Amplified Emission
pump
lpump1770nm lemmax553nm
2
Quantum Dots for bioimaging

• Compared to organic fluorophores, the major
  advantages offered by quantum dots for bioimaging
  are
•  
• Quantum dot emissions are considerably narrower
  compared to organic fluorophores, which exhibit
  broad emissions. Thus, the complication in
  simultaneous quantitative multi-channel detection
  posed by cross talks between different detection
  channels, derived from spectral overlap, is
  significantly reduced.
• The lifetime of emission is longer (hundreds of
  nanoseconds) compared to that of organic
  fluorophores, thus allowing one to utilize
  time-gated detection to suppress
  autofluorescence, which has a considerably
  shorter lifetime.
• The quantum dots do not readily photobleach.
• They are not subject to microbial attack.

3
(A) Size- and material-dependent emission spectra
of several surfactant-coated semiconductor
nanocrystals in a variety of sizes. The blue
series represents different sizes of CdSe
nanocrystals with diameters of 2.1, 2.4, 3.1, 3.6
and 4.6 nm (from right to left). The green series
is of InP nanocrystals with diameters of 3.0,
3.5, and 4.6nm. The red series is of InAs
nanocrystals with diameters of 2.8, 3.6, 4.6 and
6.0nm. (B) A true-color image of a series of
silica-coated core (CdSe)-shell (ZnS or CdS)
nanocrystal probes in aqueous buffer, all
illuminated simultaneously with a handheld
ultraviolet lamp
4
Schematics of a ZnS-capped CdSe quantum dot
covalently coupled to a protein by mercaptoacetic
acid
5
Various up-conversion processes exhibited by
rare-earth ions
 
6
Cellular Imaging
Bioimaging using up-converting nanoparticles on
oral epithelial carcinoma cells (KB). KB cells
were incubated with nanoparticles consisting of
Er-doped Y2O3 nanophosphors in silica shell.
Plate A represents the light transmission image
of the KB cells. Plate B is the fluorescent
emission after excitation with 974nm. Plate C is
the composite of Plates A and B.
7
Cellular Mechanism of Chemotherapy
The structure of Chemotherapeutic drug-carrier
(LH-RH peptide)-dye conjugate. TPLSM images of
MCF-7 cells showing the intake of drug into cell
over a time period of 50 minutes.
8
Imaging of Cell Division
Right panel shows two-photon excited imaging of
KB cell with DNA (green pseudo color) and RNA
(red pseudo color) staining with Acridine Orange.
Left panel shows the fluorescence spectra
obtained, using localized spectroscopy, from
different locations in the cell.
9
Two-Photon Imaging of Soft, Tumor Tissue
Ex vivo imaging of extracted tumor tissue from a
hamster cheek pouch showing the selective
accumulation of drug-dye conjugate in tumor
(two-photon imaging using 800nm excitation). In
this pseudocolored image, blue is the
transmission signal while red shows two-photon
fluorescence signal.
10
Two-Photon Imaging of Hard Tissue, Dental Imaging
3D reconstruction of dentinal tubule images
obtained using TPLSM. Extracted tooth was treated
with dye doped dental bonding agent and imaged
using a confocal microscope with an 800nm
excitation from a TiSapphire laser.
11
OCT Imaging of Hard Tissue, Dental Imaging
Optical Coherence Tomography Image of Cross
Section of Human Tooth
12
In-Vivo Retinal Imaging
This indocyanine green angiogram of the same
patient shows the deeper choroidal vessels. The
leaky vessels (choroidal neovascularization) are
shown well here.
13
Optical Biosensors