Beckman Laser Institute
  • 'Seeing' Inside our Skin with Multiphoton Microscopy

in vivo multiphoton microscopy human skin

Contrast mechanisms in Multiphoton Microscopy imaging


Two-photon excited fluorescence : keratin, NADH/FAD, melanin, elastin fibers

Second harmonic generation: collagen fibers











  • In vivo Multiphoton Microscopy Imaging of Melanoma in Human Skin

in vivo multiphoton microscopy melanoma human skin

  • Melanocytes advanced in the upper epidermal layers (arrows)

  • Proliferation of atypical melanocytes and architectural disorder in the basal layer

  • Melanoma cells and probably melanophages in the dermis











    • In vivo Multiphoton NADH Fluorescence Reveals Depth-Dependent Keratinocyte Metabolism in Human skin [pub]

    In vivo Multiphoton NADH Fluorescence Reveals Depth-Dependent Keratinocyte Metabolism in Human skin

    During arterial occlusion, the ischemia-induced oxygen deprivation is associated with a strong increase in NADH fluorescence of keratinocytes in layers close to stratum basale, implying a reduction in basal cell oxidative phosphorylation.











    • Fiber Delivered Probe for Efficient Coherent anti-Stokes Raman Scattering (CARS) Imaging of Tissues [pub]

    CARS fiber probe Adipocytes CARS microscopy

    We developed a fiber-based probe for maximum collection efficiency of the CARS signal in biological tissues. To spectrally suppress the strong four wave mixing signal generated in the fiber, the probe design incorporates separate fibers for light delivery and signal detection. We work on further miniaturization of this probe to optimize its use for clinical studies.[pub]











    • Effect of Excitation Wavelength on the Penetration Depth in Multiphoton Microscopy [pub]

      This project was a collaborative effort with Newport Corp. in Irvine, CA. We performed a comparative study of two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) imaging in turbid media at 800 nm and 1300 nm excitation. The depth-dependent decay of TPEF signals in turbid tissue phantoms was used to estimate the impact of light scattering on excitation intensity at each wavelength. A near two-fold increase in scattering length was observed using 1300 nm excitation, while peak emission intensity was obtained 10-20 microns beneath the surface for both sources. The increased penetration depth at 1300 nm was confirmed by TPEF microscopy of 3-D organotypic collagen-fibroblast tissue phantoms. Our results establish the feasibility of 1300 nm excitation and the role of scattering on signal degradation in non-linear optical microscopy.