Picosecond Infrared Laser (PIRL) Scalpel: Achieving Fundamental Limits to Minimally Invasive Surgery
AMO Seminar
3:00 pm
Jorgensen Hall Room: 149
Speaker: R. J. Dwayne Miller
Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, Hamburg 27761, Germany
Department of Chemistry and Physics, 80 St. George Street, University of Toronto, Toronto, Ontario M5S 3H6, Canada
The first atomic view of strongly driven phase transitions (Siwick et al, Science 2003) illustrated the mechanism to control nucleation growth to nm scales (nucleation as small as 10 molecules). To take advantage of this new insight, a laser concept was developed based on a seeded Optical Parametric Amplifier and microchip laser technology to provide a compact robust source engineered to excite the OH stretch of water in biological tissue for use in laser surgery. The laser ablation process is driven within resonant 1-photon transitions in which the strong localization of the laser energy is provided by the extremely strong absorption of water in the 3 micron range. The strong absorption of water provides intrinsic confinement of the ablation process to the micron dimensions of a single cell in the longitudinal direction with lateral confinement defined by the laser focus conditions. Lasers currently in clinical use involve either massive tissue damage due to shock wave and thermal transport resulting in burning and tissue necrosis or is highly ionizing. The PIRL scalpel was found to readily cuts all tissues types and most importantly, the damage to surrounding tissue was negligible, with no discernable scar tissue formation (Amini-Nik et al, PLoS 2010). The reduced damage to surrounding tissue was correlated to reduced expression levels of signaling proteins involved in fibroblast formation that causes scar tissue formation to reinforce this conclusion. This is the first method, by any means, capable of surgery without scar tissue formation. In this respect, the long held promise of the laser for achieving the fundamental (cell) limit to surgery has now been realized. In the process, it was also discovered that entire proteins, even protein complexes, are ejected into the gas phase intact (Ren et al., Nanotechnology 2015). This observation has been rationalized on the basis that the whole process of vibrational excitation and coupling to translational motion driving ablation occurs faster than even collisional exchange of the excited water with the constituent proteins (see Miller, Ann. Rev. Phys. Chem. 1989) and the ensuing ablation occurs on time scales much faster than thermal fragmentation of the protein signatures. This new laser ablation mechanism referred to as Desorption by Impulsive Vibrational Excitation (DIVE) provides a new means for in situ spatial mapping with mass spectroscopy in which preliminary results show very detailed molecular fingerprints of different tissue types. An imaging mass spectrometer is being designed, based on lessons from the high brightness electron source development in the group, that should be capable of near unit ion and detection efficiency, to provide significant gains in sensitivity in mass spectroscopy. Preliminary results for ambient injection conditions relevant for laser surgery show that this method is capable of near attomolar sensitivity, which is near theoretical limits in terms of the collection and detector efficiency. The applications of basic research have turned full circle in which the technology developed for medical applications is now making the scientific case for Making a Molecular Map of the Cell – to reveal the essential nonlinear physics/biochemistry breathing life into otherwise inanimate matter.
Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, Hamburg 27761, Germany
Department of Chemistry and Physics, 80 St. George Street, University of Toronto, Toronto, Ontario M5S 3H6, Canada
The first atomic view of strongly driven phase transitions (Siwick et al, Science 2003) illustrated the mechanism to control nucleation growth to nm scales (nucleation as small as 10 molecules). To take advantage of this new insight, a laser concept was developed based on a seeded Optical Parametric Amplifier and microchip laser technology to provide a compact robust source engineered to excite the OH stretch of water in biological tissue for use in laser surgery. The laser ablation process is driven within resonant 1-photon transitions in which the strong localization of the laser energy is provided by the extremely strong absorption of water in the 3 micron range. The strong absorption of water provides intrinsic confinement of the ablation process to the micron dimensions of a single cell in the longitudinal direction with lateral confinement defined by the laser focus conditions. Lasers currently in clinical use involve either massive tissue damage due to shock wave and thermal transport resulting in burning and tissue necrosis or is highly ionizing. The PIRL scalpel was found to readily cuts all tissues types and most importantly, the damage to surrounding tissue was negligible, with no discernable scar tissue formation (Amini-Nik et al, PLoS 2010). The reduced damage to surrounding tissue was correlated to reduced expression levels of signaling proteins involved in fibroblast formation that causes scar tissue formation to reinforce this conclusion. This is the first method, by any means, capable of surgery without scar tissue formation. In this respect, the long held promise of the laser for achieving the fundamental (cell) limit to surgery has now been realized. In the process, it was also discovered that entire proteins, even protein complexes, are ejected into the gas phase intact (Ren et al., Nanotechnology 2015). This observation has been rationalized on the basis that the whole process of vibrational excitation and coupling to translational motion driving ablation occurs faster than even collisional exchange of the excited water with the constituent proteins (see Miller, Ann. Rev. Phys. Chem. 1989) and the ensuing ablation occurs on time scales much faster than thermal fragmentation of the protein signatures. This new laser ablation mechanism referred to as Desorption by Impulsive Vibrational Excitation (DIVE) provides a new means for in situ spatial mapping with mass spectroscopy in which preliminary results show very detailed molecular fingerprints of different tissue types. An imaging mass spectrometer is being designed, based on lessons from the high brightness electron source development in the group, that should be capable of near unit ion and detection efficiency, to provide significant gains in sensitivity in mass spectroscopy. Preliminary results for ambient injection conditions relevant for laser surgery show that this method is capable of near attomolar sensitivity, which is near theoretical limits in terms of the collection and detector efficiency. The applications of basic research have turned full circle in which the technology developed for medical applications is now making the scientific case for Making a Molecular Map of the Cell – to reveal the essential nonlinear physics/biochemistry breathing life into otherwise inanimate matter.