Presentations

    High Throughput Poration of Mammalian Cells using Femtosecond Laser-activated Plasmonic Substrates, at Tokyo Metropolitan University (Tokyo, Japan), Thursday, January 29, 2015:
    We present a new cell transfection method that uses femtosecond laser-excited localized surface plasmons (LSPs) on a nanostructured micropyramid array. Our gold-layered micropyramids have nano-apertures at the apex to form high local electric field enhancements, or “hot spots.” These hot spots form microbubbles that temporarily perforate mammalian cell (HeLa S3) membranes and allow dye molecules and plasmid vectors to diffuse through the membrane openings. We optimize our laser parameters for successful poration and high cell viability. Our nontoxic, efficient, and scalable technique... Read more about High Throughput Poration of Mammalian Cells using Femtosecond Laser-activated Plasmonic Substrates
    Laser-induced microexplosions: ultrafast physics with clinical applications, at 20th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (Hong Kong), Thursday, October 29, 1998:
    We used water and human skin tissue to compare the surgical potential of 100-fs and 200-ps laser pulses. For investigation of threshold behavior of 100-fs and 200-ps pulses, we use water as a model for tissue. In addition to having a lower threshold, we find that energy deposition is much more consistent with 100-fs pulses. We also compared 100-fs and 200-ps laser pulse effects on the surface and in the bulk of human skin tissue. On the surface, pulses with 100-fs and 200-ps duration leave similar size ablation regions. In the bulk both 100-fs and 200-ps pulses produce cavities, however, 100-... Read more about Laser-induced microexplosions: ultrafast physics with clinical applications
    Laser-induced microexplosions: Ultrafast physics with clinical applications, at Physics Colloquium, Texas A&M University (College Station, TX), Thursday, February 18, 1999:
    Recently there has been much interest in using femtosecond laser pulses in surgical applications. For example, femtosecond lasers could replace the nanosecond systems currently used for opthalmic photodisruption, providing improved surgical precision and adding versatility. In surgical applications, it is the high intensity of femtosecond laser pulses that is exploited. By tightly focusing these short pulses, the intensity becomes high enough to cause nonlinear absorption inside a transparent material (such as the vitreous humor). The absorption produces a hot plasma inside the sample that is... Read more about Laser-induced microexplosions: Ultrafast physics with clinical applications
    Photodisruption in turbid tissue with 100-fs and 200-ps laser pulses, at APS Centennial Meeting 1999 (Atlanta, GA), Friday, March 26, 1999:
    We compare the potential of 100-fs and 200-ps laser pulses for photodisruptive surgery on the surface and in the bulk of turbid tissue. Water, human epidermis cultures, and pig skin were used as tissue models. In our technique, tightly-focused femtosecond and picosecond laser pulses are nonlinearly absorbed, vaporizing tissue in the focal volume. We find that there are several advantages in using femtosecond pulses for photodisruption. The breakdown threshold is lower and the energy deposition is more deterministic for 100-fs pulses compared to 200-ps pulses. In human skin culture we observe... Read more about Photodisruption in turbid tissue with 100-fs and 200-ps laser pulses
    Photodisruption in turbid tissues with ultrashort laser pulses, at Photonics West 2000 (San Jose, CA), Tuesday, January 25, 2000:
    We investigate the potential of femtosecond laser pulses for photodusruptive surgery on the surface and in the bulk of turbid tissue. Human epidermis cultures, mouse skin, and pig skin were used as tissue models. We use nonlinear absorption of tightly focused 100-fs laser pulses to vaporize tissue in the focal volume. By focusing the pulse in the bulk of the skin, we can vaporize 10-µm diameter regions up to 100 µm beneath the surface with minimal damage to the surrounding tissue. This technique offers exciting possibilities for clinical dermatology applications, such as tattoo removal and... Read more about Photodisruption in turbid tissues with ultrashort laser pulses
    Photodisruption in biological samples using femtosecond laser pulses, at Photonic West Conference (San Jose, CA), Tuesday, January 23, 2001:
    Tightly focused femtosecond laser pulses can be absorbed nonlinearly inside biological materials, vaporizing tissue in the focal volume. High intensity is achieved at the focus with relatively low energy, minimizing collateral damage and unwanted heat deposition. We focus 100-fs laser pulses using a high numerical aperture microscope objective in the bulk of the skin tissue, disrupting micrometer-sized regions up to 100 mm beneath the sample surface. When the laser beam is focused even deeper into the sample, we observe the formation of filaments in the skin bulk rather than spherical sub-... Read more about Photodisruption in biological samples using femtosecond laser pulses
    Manipulation of Single Cells with Sub-cellular Precision Using Femtosecond Laser Pulses, at Photonics West, Commercial and Biomedical Applications of Ultrafast Lasers IV (San Jose, CA), Wednesday, January 23, 2002:
    Femtosecond laser pulses centered at 800 nm are used to manipulate sub-cellular structures inside live and fixed cells. Using only a few nanojoules of laser pulse energy, we are able to selectively disrupt individual mitochondria in live bovine capillary epithelial (BCE) cells, and cleave single actin fibers in the cell cytoskeleton network of fixed human fibro-blast cells. We tightly focus femtosecond laser pulses using high numerical aperture (NA) microscope objectives to create high laser intensity in the sub-micrometer-sized focal volume. Laser energy is absorbed through non-linear... Read more about Manipulation of Single Cells with Sub-cellular Precision Using Femtosecond Laser Pulses
    Sub-cellular nanosurgery in live cells using ultrashort laser pulses, at Photonics West (San Jose, CA), Friday, January 21, 2005:
    We use femtosecond laser pulses to selectively disrupt the cytoskeleton of a living cell and probe its mechanical properties. The nanosurgery setup is based on a home-built two-photon microscope. To image, we use a 80-MHz, 100-pJ/pulse laser beam, which is scanned across the sample; to cut, we introduce a second, 250-kHz, 1 to 5-nJ/pulse, laser beam and locally ablate sub-cellular structures. Simultaneous cutting and imaging allows us to study immediate cellular response with several hundred-nanometer spatial and less than 500-ms time resolution. We severed single actin bundles inside live... Read more about Sub-cellular nanosurgery in live cells using ultrashort laser pulses
    Nanosurgery in live cells using ultrashort laser pulses, at 2005 SPIE Photonics West Conference (San Jose, CA), Tuesday, January 25, 2005:
    We selectively disrupted the cytoskeletal network of a live bovine capillary endothelial cell using ultrashort laser pulses. We image the microtubules in the cytoskeleton of the cultured cells using green fluorescent protein. The cells are placed on a custom-built inverted fluorescence microscope setup, using a 1.4 NA oil-immersion objective to both image the cell and focus the laser radiation into the cell samples. The laser delivers 100-fs laser pulses centered at 800 nm at a repetition rate of 1 kHz; the typical energy delivered at the sample is 1–5nJ. The fluorescent image of the cell is... Read more about Nanosurgery in live cells using ultrashort laser pulses
    Sub-cellular femtosecond laser ablation, at 2005 SPIE Photonics West Conference (San Jose, CA), Wednesday, January 26, 2005:
    We study the selective ablation by femtosecond laser pulses of sub-cellular structures in bovine endothelial cells, with selectively stained microtubules, actin fibers, and nuclei. The cells are placed in a custom-built inverted fluorescence microscope with a 1.4 NA oil-immersion objective. The laser used for ablation is centered at 800 nm delivering 100-fs laser pulses at a repetition rate of 1 kHz and the typical energy delivered at the sample is 1–5nJ. To determine the structural change and the size of the laser-affected area, we use transmission electron microscopy (TEM), in addition to... Read more about Sub-cellular femtosecond laser ablation
    Femtosecond laser dissection of neurons in C. elegans, at Industrial Outreach Program, Harvard University (Cambridge, MA), Wednesday, April 27, 2005:
    Tightly-focused femtosecond laser pulses of a few nanojoules sever individual dendrites in the nematode worm C. elegans. Quantification of the resulting behavioral deficits identifies the contribution of the dissected structures. The dissection has submicrometer resolution with no collateral damage, permitting precise studies on live animals. Future work include an examination of the molecular basis of neurodegeneration that has application to diseases such as Parkinsons and Alzheimers.
    Femtosecond laser dissection of neurons in C. elegans, at NATO ASI Course on New developments in optics and related fields: modern techniques, materials, and applications, Centro Ettore Majorana (Erice, Italy), Tuesday, June 14, 2005:
    Tightly-focused femtosecond laser pulses of a few nanojoules sever individual dendrites in the nematode worm C. elegans. Quantification of the resulting behavioral deficits identifies the contribution of the dissected structures. Due to nonlinear absorption of laser light, the dissection has submicrometer resolution with no collateral damage, permitting subcellular surgery on live animals. Future work include an examination of the molecular basis of neurodegeneration that has application to diseases such as Parkinsons and Alzheimers.
    Subcellular surgery and nanoneurosurgery, at A Year of Physics Colloquium, North Carolina A&T State University (Greensboro, NC), Thursday, November 10, 2005:
    We use femtosecond laser pulses to manipulate sub-cellular structures inside live and fixed cells. Using only a few nanojoules of laser pulse energy, we are able to selectively disrupt individual mitochondria in live bovine capillary epithelial cells, and cleave single actin fibers in the cell cytoskeleton network of fixed human fibro-blast cells. We have also used the technique to micromanipulate the neural network of C. Elegans, a small nematode. Our laser scalpel can snip individual axons without causing any damage to surrounding tissue, allowing us to study the function of individual... Read more about Subcellular surgery and nanoneurosurgery
    Single neuron dissection in C. elegans by femtosecond laser pulses, at Photonics West 2006 (San Jose, CA), Saturday, January 21, 2006:
    Using tightly-focused, 2-5 nJ femtosecond laser pulses we disrupt cellular material in the nematode worm C. elegans. Due to the nonlinear absorption of laser light, the dissection has submicrometer resolution, yielding surgery within the bulk of the worm without incision. The low energy of the pulses minimizes collateral damage. This technique permits subcellular surgery on live animals and opens a wide range of neurobiological questions to study in vivo.

    We severed individual dendrites of a thermosensory neuron without damaging nearby neurons. Quantification of the resulting behavioral...

    Read more about Single neuron dissection in C. elegans by femtosecond laser pulses
    Sub-cellular nanosurgery in live cells using ultrashort laser pulses, at Photonics West 2006 (San Jose, CA), Sunday, January 22, 2006:
    We use femtosecond laser pulses to selectively disrupt the cytoskeleton of a living cell and probe its mechanical properties. The nanosurgery setup is based on a home-built two-photon microscope. To image, we use a 80-MHz, 100-pJ/pulse laser beam, which is scanned across the sample; to cut, we introduce a second, 250-kHz, 1 to 5-nJ/pulse, laser beam and locally ablate sub-cellular structures. Simultaneous cutting and imaging allows us to study immediate cellular response with several hundred-nanometer spatial and less than 500-ms time resolution.

    We severed single actin bundles inside...

    Read more about Sub-cellular nanosurgery in live cells using ultrashort laser pulses
    Subcellular surgery and nanosurgery, at CIMIT/Lester Wolfe Workshop on Femtosecond Microscopy & Microsurgery, Wellman Center for Photomedicine (Boston, MA), Tuesday, April 18, 2006:
    We use femtosecond laser pulses to manipulate sub-cellular structures inside live and fixed cells. Using only a few nanojoules of laser pulse energy, we are able to selectively disrupt individual mitochondria in live bovine capillary epithelial cells, and cleave single actin fibers in the cell cytoskeleton network of fixed human fibro-blast cells. We have also used the technique to micromanipulate the neural network of C. Elegans, a small nematode. Our laser scalpel can snip individual axons without causing any damage to surrounding tissue, allowing us to study the function of individual... Read more about Subcellular surgery and nanosurgery

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