Dr. Benno Radt Profile

Dr. Benno Radt

at Carl Zeiss Microscopy GmbH

SPIE Involvement:

Author

Publications (6)

Proceedings Article | 2 May 2008 Paper

Identification of active fluorescence stained bacteria by Raman spectroscopy

Mario Krause, Beatrice Beyer, Christian Pietsch, Benno Radt, Michaela Harz, Petra Rösch, Jürgen Popp

Proceedings Volume 6991, 69910E (2008) https://doi.org/10.1117/12.781321

KEYWORDS: Raman spectroscopy, Luminescence, Bacteria, Particles, Microorganisms, Absorption, Raman scattering, Biological research, Laser scattering, Scattering

Read Abstract +

Proceedings Article | 16 October 2003 Paper

Inactivation of proteins by irradiation of gold nanoparticles with nano- and picosecond laser pulses

Gereon Huettmann, Benno Radt, Jesper Serbin, Reginald Birngruber

Proceedings Volume 5142, (2003) https://doi.org/10.1117/12.500525

KEYWORDS: Proteins, Gold, Particles, Picosecond phenomena, Nanoparticles, Absorption, Pulsed laser operation, Laser tissue interaction, Laser therapeutics, Gaussian beams

Read Abstract +

Proceedings Article | 26 October 2001 Paper

Laser-generated micro- and nanoeffects: inactivation of proteins coupled to gold nanoparticles with nano- and picosecond pulses

Benno Radt, Jesper Serbin, Bjoern Lange, Reginald Birngruber, Gereon Huettmann

Proceedings Volume 4433, (2001) https://doi.org/10.1117/12.446518

KEYWORDS: Proteins, Picosecond phenomena, Gold, Particles, Laser tissue interaction, Luminescence, Absorption, Temperature metrology, Nanoparticles, Photochemistry

Read Abstract +

Background: Protein denaturation in the fs-ns time regime is of fundamental interest for high precision applications in laser tissue interaction. Conjugates of colloidal gold coupled to proteins are presented as a model system for investigating ultrafast protein denaturation. It is expected that irradiation of such conjugates in tissue using pico- up to nanosecond laser pulses could result in effects with a spatial confinement in the regime of single macromolecules up to organelles. Materials and Methods: Experiments were done with bovine intestinal alkaline phosphatase (aP) coupled to 15 nm colloidal Gold. This complex was irradiated at 527 nm/ 532 nm with a variable number of pico- and nanosecond pulses. The radiant exposure per pulse was varied from 2 to 50 mJ/cm² in the case of the picosecond pulses and 10 to 500 mJ/cm² in the case of the nanosecond pulses. Denaturation was detected as a loss of protein function with the help of the uorescence substrate 4MUP. Results and Discussion: Irradiation did result in a steady decrease of the aP activity with increasing radiant exposures and increasing number of pulses. Inactivations up to 80% using 35 ps pulses at 527 nm with 50 mJ/cm² and a complete inactivation induced by 16 ns pulses at 450 mJ/cm² are discussed. The induced temperature in the particles and the surrounding water was calculated using Mie's formulas for the absorption of the nanometer gold particles and an analytical solution of the equations for heat diffusion. The calculated temperatures suggest that picosecond pulses heat a molecular scaled area whereas nanosecond pulses could be used for targeting larger cellular compartiments. It is difficult to identify one of the possible damage mechanisms, i.e. thermal denaturation or formation of micro bubbles, from the dependance of the inactivation on pulse energy and number of applied pulses. Therefore experiments are needed to further elucidate the damage mechanisms. The observed inactivation dependencies on applied energy and radiant power can not be explained with one or two photon photochemistry. In conclusion, denaturing proteins irreversibly via nanoabsorbers using pico-/ nanosecond laser pulses is possible. The expected confinement of the heat to the nanoabsorbers suggests that denaturation of proteins with nanometer precision could be possible with this approach. However, the mechanism of protein inactivation, which is part of present investigations, is crucial for the precision of such nanoeffects.

Proceedings Article | 9 July 2001 Paper

Model system for investigating laser-induced subcellular microeffects

Gereon Huettmann, Jesper Serbin, Benno Radt, Bjoern Lange, Reginald Birngruber

Proceedings Volume 4257, (2001) https://doi.org/10.1117/12.434739

KEYWORDS: Proteins, Particles, Picosecond phenomena, Gold, Luminescence, Absorption, Laser tissue interaction, Diffusion, Laser applications, Water

Read Abstract +

Background: Laser induced protein denaturation is of fundamental interest for understanding the mechanisms of laser tissue interaction. Conjugates of nanoabsorbers coupled to proteins are presented as a model system for investigating ultrafast protein denaturation. Irradiation of the conjugates using repetitive picosecond laser pulses, which are only absorbed by the nanoabsorbers, could result in effects with a spatial confinement of less than 100 nm. Materials and Methods: Experiments were done with bovine intestinal alkaline phosphates (aP) coupled to 15 nm colloidal gold. This complex was irradiated at 527 nm wavelength and 35 ps pulse width with a varying number of pulses ranging form one up to 10⁴. The radiant exposure per pulse was varied form 2 mJ/cm² to 50 mJ/cm². Denaturation was detected as a loss of protein function with the help of the fluorescence substrate 4MUP. Results and discussion: Irradiation did result in a steady decrease of the aP activity with increasing radiant exposures and increasing number of pulses. A maximal inactivation of 80% was reached with 10⁴ pulses and 50 mJ/cm² per pulse. The temperature in the particles and the surrounding water was calculated using Mie's formulas for the absorption of the nanometer gold particles and ana analytical solution of the equations for heat diffusion. With 50 mJ/cm², the particles are heated above the melting point of gold. Since the temperature calculations strongly depend on changes in the state of matter of the particles and water, a very sophisticated thermal model is necessary to calculate exact temperatures. It is difficult to identify one of the possible mechanisms, thermal denaturation, photochemical denaturation or formation of micro bubbles from the dependance of the inactivation on pulse energy and number of applied pulses. Therefore, experiments are needed to further elucidate the damage mechanisms. In conclusion, denaturing proteins irreversibly via nanoabsorbers using picosecond laser pulses is possible. The confinement of the heat to the nanoabsorbers when irradiating with picosecond pulses suggests that the denaturation of proteins could be possible with nanometer precision in cells with this approach. However, the mechanism of protein inactivation, which is part of present investigations, is crucial for the precision of such nanoeffects.

Proceedings Article | 16 April 2001 Paper

Cr,Tm,Ho: YAG laser amplifier

Bjoern Lange, Benno Radt, Gereon Huettmann

Proceedings Volume 4267, (2001) https://doi.org/10.1117/12.424616

KEYWORDS: Amplifiers, Oscillators, Holmium, Pulsed laser operation, Mirrors, Absorption, Resonators, YAG lasers, Data modeling, Laser amplifiers

Read Abstract +

Proceedings Article | 22 December 1997 Paper

Laser thermokeratoplasty: analysis of in-vitro results and refractive changes achieved in a first clinical study

Ralf Brinkmann, Gerd Geerling, Juergen Kampmeier, Norbert Koop, Benno Radt, Reginald Birngruber

Proceedings Volume 3192, (1997) https://doi.org/10.1117/12.297840

KEYWORDS: Temperature metrology, In vitro testing, Collagen, Laser vision correction, Monochromatic aberrations, Continuous wave operation, Mid-IR, Semiconductor lasers, Clinical trials, Cornea

Read Abstract +

Showing 5 of 6 publications

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years