Sebastian Kruber

Ultrafast extraction of proteins from tissues using desorption by impulsive vibrational excitation.

A picosecond IR laser (PIRL) can be used to blast proteins out of tissues through desorption by impulsive excitation (DIVE) of intramolecular vibrational states of water molecules in the cell in less than a millisecond. With PIRL-DIVE proteins covering a range of a few kDa up to several MDa are extracted in high quantities compared to conventional approaches. The chemical composition of extracted proteins remains unaltered and even enzymatic activities are maintained.

The Petawatt Field Synthesizer: A New Approach to Ultrahigh Field Generation

The Petawatt Field Synthesizer (PFS) at MPQ will deliver few-cycle pulses at Petawatt power. Short-pulse OPCPA and a diode-pumped, CPA Yb:YAG pump laser are key technologies, and results of the ongoing development will be presented.

Homogenization of tissues via picosecond-infrared laser (PIRL) ablation: Giving a closer view on the in-vivo composition of protein species as compared to mechanical homogenization

Posttranslational modifications and proteolytic processing regulate almost all physiological processes. Dysregulation can potentially result in pathologic protein species causing diseases. Thus, tissue species proteomes of diseased individuals provide diagnostic information. Since the composition of tissue proteomes can rapidly change during tissue homogenization by the action of enzymes released from their compartments, disease specific protein species patterns can vanish. Recently, we described a novel, ultrafast and soft method for cold vaporization of tissue via desorption by impulsive vibrational excitation (DIVE) using a picosecond-infrared-laser (PIRL). Given that DIVE extraction may provide improved access to the original composition of protein species in tissues, we compared the proteome composition of tissue protein homogenates after DIVE homogenization with conventional homogenizations. A higher number of intact protein species was observed in DIVE homogenates. Due to the ultrafast transfer of proteins from tissues via gas phase into frozen condensates of the aerosols, intact protein species were exposed to a lesser extent to enzymatic degradation reactions compared with conventional protein extraction. In addition, total yield of the number of proteins is higher in DIVE homogenates, because they are very homogenous and contain almost no insoluble particles, allowing direct analysis with subsequent analytical methods without the necessity of centrifugation. Biological significance Enzymatic protein modifications during tissue homogenization are responsible for changes of the in-vivo protein species composition. Cold vaporization of tissues by PIRL-DIVE is comparable with taking a snapshot at the time of the laser irradiation of the dynamic changes that occur continuously under in-vivo conditions. At that time point all biomolecules are transferred into an aerosol, which is immediately frozen.

Comparative study of wound healing in rat skin following incision with a novel picosecond infrared laser (PIRL) and different surgical modalities

As a result of wound healing the original tissue is replaced by dysfunctional scar tissue. Reduced tissue damage during surgical procedures beneficially affects the size of the resulting scar and overall healing time. Thus the choice of a particular surgical instrument can have a significant influence on the postoperative wound healing. To overcome these problems of wound healing we applied a novel picosecond infrared laser (PIRL) system to surgical incisions. Previous studies indicated that negligible thermal, acoustic, or ionization stress effects to the surrounding tissue results in a superior wound healing.

OPA development on the Petawatt Field Synthesizer

We report on recent OPCPA progress at the PFS system.We present a scheme for generating a broadband (700 nm-1400 nm) seed pulse for OPA, and a new preamplifier setup for the CPA pump laser chain.

Short-pulse optical parametric chirped-pulse amplification for the generation of high-power few-cycle pulses

This paper demonstrates ultrabroadband optical parametric chirped-pulse amplification (OPCPA) with 100-fs pulses in the 100-muJ range. By using OPA for amplifying mainly the weak part of the filament-broadened spectrum much shorter pulses with an improved uniformity of the spectral intensity can be achieved as compared to the direct compression of the filament output. In order to increase the signal pulse energy to the multi-mJ level an improved spatial filter using a tapered glass capillary pinhole is under construction to allow for using a much larger part of the ATLAS output energy for pumping. Furthermore, the high available seed energy of 1 mJ could allow for reaching the 100 mJ level with small amplification factors in a multi-stage OPCPA system where saturation in all stages is beneficial for signal stability and pulse contrast. Scaling of the short-pulse OPCPA scheme to petawatt level is also planned.

Picosecond Infrared Laser (PIRL) Application in Stapes Surgery—First Experience in Human Temporal Bones

Objective: Using a contact-free laser technique for stapedotomy reduces the risk of mechanical damage of the stapes footplate. However, the risk of inner ear dysfunction due to thermal, acoustic, or direct damage has still not been solved. The objective of this study was to describe the first experiences in footplate perforation in cadaver tissue performed by the novel Picosecond-Infrared-Laser (PIRL), allowing a tissue preserving ablation. Patients and Intervention: Three human cadaver stapes were perforated using a fiber-coupled PIRL. The results were compared with footplate perforations performed with clinically applied Er:YAG laser. Therefore, two different laser energies for the Er:YAG laser (30 and 60 mJ) were used for footplate perforation of three human cadaver stapes each. Main Outcome Measure: Comparisons were made using histology and environmental scanning electron microscopy (ESEM) analysis. Results: The perforations performed by the PIRL (total energy: 640–1070 mJ) revealed a precise cutting edge with an intact trabecular bone structure and no considerable signs of coagulation. Using the Er:YAG-Laser with a pulse energy of 30 mJ (total energy: 450–600 mJ), a perforation only in the center of the ablation zone was possible, whereas with a pulse energy of 60 mJ (total energy: of 195–260 mJ) the whole ablation zone was perforated. For both energies, the cutting edge appeared irregular with trabecular structure of the bone only be conjecturable and signs of superficial carbonization. Conclusion: The microscopic results following stapes footplate perforation suggest a superiority of the PIRL in comparison to the Er:YAG laser regarding the precision and tissue preserving ablation.

Digital interference microscopy and density reconstruction of picosecond infrared laser desorption at the water-air interface

Material ablation and evaporation using pulsed infrared lasers pose promising approaches for matrix-free laser desorption ionization and in laser surgery. For the best results, key parameters such as laser wavelength, pulse duration, and pulse energy need to be carefully adjusted to the application. We characterize the dynamics at the water-air interface induced by a 10 ps infrared laser tuned to the water absorption band at 3 μ m, a parameter set facilitating stress confined desorption for typical absorption depths in biological samples and tissue. By driving the ablation faster than nucleation growth, cavitation induced sample damage during the ablation process can be mitigated. The resultant explosive ablation process leads to a shock front expansion and material ejection which we capture using off-axis digital interference microscopy, an interference technique particularly useful for detecting the phase shift caused by transparent objects. It is demonstrated that the method can yield local density...