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11. Hydrogels for light delivery in in vivo optogenetic applications

Author

Johannsmeier, Sonja, Torres-Mapa, Maria L., Ripken, Tammo, Heinemann, Dag, Heisterkamp, Alexander, Amelink, Arjen, and Nadkarni, Seemantini K.

Subjects
Materials science, Dewey Decimal Classification::600 | Technik::620 | Ingenieurwissenschaften und Maschinenbau, technology, industry, and agriculture, Optogenetics, Light delivery, complex mixtures, Hydrogel waveguide, In vivo, Self-healing hydrogels, Biophysics, ddc:620, Diffusor, Konferenzschrift
Abstract

Biocompatible hydrogels present interesting opportunities for in vivo waveguiding for optogenetic or photomedical applications. Here, we investigate the applicability of poly(ethylene glycol) diacrylate hydrogels in combination with scattering particles as optical diffusors. Gel characteristics and bioactivity can be tuned to achieve controlled light distribution and tissue interaction.

Published
2019

12. Investigation of second harmonic generation and multispectral imaging as new contrast mechanisms in scanning laser optical tomography

Author

Nolte, Lena, Antonopoulos, Georgios C., Heisterkamp, Alexander, Ripken, Tammo, Meyer, Heiko, Brown, Thomas G., Cogswell, Carol J., and Wilson, Tony

Subjects
Nonlinear optics, Materials science, Tomographic imaging, Multispectral image, Iterative reconstruction, 3-D microscopy, Multispectral imaging, Harmonic analysis, Optics, medicine, High harmonic generation, Scanning, Scanning lasers, ddc:610, Light sources, Optical tomography, Konferenzschrift, Tomographic reconstruction, Harmonic generation, medicine.diagnostic_test, business.industry, 3D Microscopy, Biological materials, Image acquisition, Second-harmonic generation, Computerized tomography, Scanning Laser Optical Tomography, Second Harmonic Generation, Supercontinuum, Autofluorescence, Image reconstruction, Dewey Decimal Classification::600 | Technik::610 | Medizin, Gesundheit, business, Spectral unmixing
Abstract

Scanning laser optical tomography (SLOT) is a 3D imaging technique, based on the principle of computed tomography to visualize samples up to magnitude of several centimeters. Intrinsic contrast mechanisms as absorption, scattering and autofluorescence provide information about the 3D architecture and composition of the sample. Another valuable intrinsic contrast mechanism is second harmonic generation (SHG), which is generated in noncentrosymmetric materials and commonly used to image collagen in biological samples. The angular dependence of the SHG signal, however, produces artifacts in reconstructed optical tomography datasets (OPT, SLOT). Thus, successful use of this intrinsic contrast mechanism is impaired. We investigate these artifacts by simulation and experiment and propose an elimination procedure that enables successful reconstruction of SHG-SLOT data. Nevertheless, in many cases specific labeling of certain structures is necessary to make them visible. Using multiple dyes in one sample can lead to crosstalk between the different channels and reduce contrast of the images. Also autofluorescence of the sample itself can account for that. By using multispectral imaging in combination with spectral unmixing techniques, this loss can be compensated. Therefore either a spectrally resolved detection path, or spectrally resolved excitation is required. Therefore we integrated a white supercontinuum light source in our SLOT-setup that enables a spectral selection of the excitation beam and extended the detection path to a four channel setup. This enables the detection of three fluorescence channels and one absorption channel in parallel, and increases the contrast in the reconstructed 3D images significantly. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

Published
2018

19. Holographically generated structured illumination for cell stimulation in optogenetics

Author

Schmieder, Felix, Büttner, Lars, Czarske, Jürgen, Leilani Torres, Maria, Heisterkamp, Alexander, Klapper, Simon, Busskamp, Volker, Schmieder, Felix, Büttner, Lars, Czarske, Jürgen, Leilani Torres, Maria, Heisterkamp, Alexander, Klapper, Simon, and Busskamp, Volker

Abstract

In Optogenetics, cells, e.g. neurons or cardiac cells, are genetically altered to produce for example the lightsensitive protein Channelrhodopsin-2. Illuminating these cells induces action potentials or contractions and therefore allows to control electrical activity. Thus, light-induced cell stimulation can be used to gain insight to various biological processes. Many optogenetics studies, however, use only full field illumination and thus gain no local information about their specimen. But using modern spatial light modulators (SLM) in conjunction with computer-generated holograms (CGH), cells may be stimulated locally, thus enabling the research of the foundations of cell networks and cell communications. In our contribution, we present a digital holographic system for the patterned, spatially resolved stimulation of cell networks. We employ a fast ferroelectric liquid crystal on silicon SLM to display CGH at up to 1.7 kHz. With an effective working distance of 33 mm, we achieve a focus of 10 µm at a positioning accuracy of the individual foci of about 8 µm. We utilized our setup for the optogenetic stimulation of clusters of cardiac cells derived from induced pluripotent stem cells and were able to observe contractions correlated to both temporal frequency and spatial power distribution of the light incident on the cell clusters.

Published
2017

20. Signal and response properties indicate an optoacoustic effect underlying the intra-cochlear laser-optical stimulation

Author

Kallweit, Nicole, Baumhoff, Peter, Krueger, Alexander, Tinne, Nadine, Heisterkamp, Alexander, Kral, Andrej, Maier, Hannes, Ripken, Tammo, Choi, Bernard, Kollian, Nikiforos, Zeng, Haishan, Kang, Hyun Wook, Wong, Brian J.F., Ilgner, Justus F., Tearney, Guillermo J., Gregory, Kenton W., Marcu, Laura, Skala, Melissa C., Campagnola, Paul J., and Mandelis, Andreas

Subjects
Materials science, Dewey Decimal Classification::600 | Technik::620 | Ingenieurwissenschaften und Maschinenbau, Stimulation, 01 natural sciences, Absorption, law.invention, 010309 optics, 03 medical and health sciences, 0302 clinical medicine, Optics, law, 0103 physical sciences, otorhinolaryngologic diseases, medicine, Infrared radiation, Konferenzschrift, Cochlea, Spiral ganglion, Photoacoustic effect, Sensors, business.industry, Pulse duration, Pulsed laser operation, Laser, medicine.anatomical_structure, Amplitude, Attenuation coefficient, In vivo imaging, Laser systems engineering, sense organs, ddc:620, business, 030217 neurology & neurosurgery, Signal detection
Abstract

Optical cochlea stimulation is under investigation as a potential alternative to conventional electric cochlea implants in treatment of sensorineural hearing loss. If direct optical stimulation of spiral ganglion neurons (SGNs) would be feasible, a smaller stimulation volume and, therefore, an improved frequency resolution could be achieved. However, it is unclear whether the mechanism of optical stimulation is based on direct neuronal stimulation or on optoacoustics. Animal studies on hearing vs. deafened guinea pigs already identified the optoacoustic effect as potential mechanism for intra-cochlear optical stimulation. In order to characterize the optoacoustic stimulus more thoroughly the acoustic signal along the beam path of a pulsed laser in water was quantified and compared to the neuronal response properties of hearing guinea pigs stimulated with the same laser parameters. Two pulsed laser systems were used for analyzing the influence of variable pulse duration, pulse energy, pulse peak power and absorption coefficient. Preliminary results of the experiments in water and in vivo suggesta similar dependency of response signals on the applied laser parameters: Both datasets show an onset and offset signal at the beginning and the end of the laser pulse. Further, the resulting signal amplitude depends on the pulse peak power as well as the temporal development of the applied laser pulse. The data indicates the maximum of the first derivative of power as the decisive factor. In conclusion our findings strengthen the hypothesis of optoacoustics as the underlying mechanism for optical stimulation of the cochlea. © SPIE 2016

Published
2016

21. Effects of polarization and absorption on laser induced optical breakdown threshold for skin rejuvenation

Author

Varghese, Babu, Bonito, Valentina, Turco, Simona, Verhagen, Rieko, Heisterkamp, Alexander, Meunier, Michel, Nolte, Stefan, Herman, Peter R., Soft Tissue Biomech. & Tissue Eng., Biomedical Diagnostics Lab, and Signal Processing Systems

Subjects
Materials science, Irradiance, Physics::Optics, 02 engineering and technology, Electron, 01 natural sciences, Light scattering, law.invention, 010309 optics, Optics, law, 0103 physical sciences, Thermal, Laser Induced Optical Breakdown, Skin rejuvenation, Multiphoton absorption, Irradiance threshold, business.industry, Scattering, Plasma, 021001 nanoscience & nanotechnology, Polarization (waves), Laser, Optoelectronics, 0210 nano-technology, business
Abstract

Laser induced optical breakdown (LIOB) is a non-linear absorption process leading to plasma formation at locations where the threshold irradiance for breakdown is surpassed. In this paper we experimentally demonstrate the influence of polarization and absorption on laser induced breakdown threshold in transparent, absorbing and scattering phantoms made from water suspensions of polystyrene microspheres. We demonstrate that radially polarized light yields a lower irradiance threshold for creating optical breakdown compared to linearly polarized light. We also demonstrate that the thermal initiation pathway used for generating seed electrons results in a lower irradiance threshold compared to multiphoton initiation pathway used for optical breakdown.

Published
2016

28. 3D ultrafast laser scanner

Author

Heisterkamp, Alexander, Mahjoubfar, A., Goda, Keisuke, Wang, Chao, Fard, Ali M., Adam, Jost, Gossett, Daniel R., Ayazi, Ali, Sollier, Elodie, Malik, Omer, Chen, E., Liu, Y., Brown, Rupert, Sarkhosh, N., Di Carlo, Dino, Jalali, Bahram, Herman, Peter R., Meunier, Michel, Nolte, Stefan, Heisterkamp, Alexander, Mahjoubfar, A., Goda, Keisuke, Wang, Chao, Fard, Ali M., Adam, Jost, Gossett, Daniel R., Ayazi, Ali, Sollier, Elodie, Malik, Omer, Chen, E., Liu, Y., Brown, Rupert, Sarkhosh, N., Di Carlo, Dino, Jalali, Bahram, Herman, Peter R., Meunier, Michel, and Nolte, Stefan

Abstract

Laser scanners are essential for scientific research, manufacturing, defense, and medical practice. Unfortunately, often times the speed of conventional laser scanners (e.g., galvanometric mirrors and acousto-optic deflectors) falls short for many applications, resulting in motion blur and failure to capture fast transient information. Here, we present a novel type of laser scanner that offers roughly three orders of magnitude higher scan rates than conventional methods. Our laser scanner, which we refer to as the hybrid dispersion laser scanner, performs inertia-free laser scanning by dispersing a train of broadband pulses both temporally and spatially. More specifically, each broadband pulse is temporally processed by time stretch dispersive Fourier transform and further dispersed into space by one or more diffractive elements such as prisms and gratings. As a proof-of-principle demonstration, we perform 1D line scans at a record high scan rate of 91 MHz and 2D raster scans and 3D volumetric scans at an unprecedented scan rate of 105 kHz. The method holds promise for a broad range of scientific, industrial, and biomedical applications. To show the utility of our method, we demonstrate imaging, nanometer-resolved surface vibrometry, and high-precision flow cytometry with real-time throughput that conventional laser scanners cannot offer due to their low scan rates. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Published
2013

29. Mask-less lithography for fabrication of optical waveguides

Author

Neev, Joseph, Nolte, Stefan, Heisterkamp, Alexander, Schaffer, Christopher B., Dubov, Mykhaylo, Natarajan, S.R., Williams, John A.R., Bennion, Ian, Neev, Joseph, Nolte, Stefan, Heisterkamp, Alexander, Schaffer, Christopher B., Dubov, Mykhaylo, Natarajan, S.R., Williams, John A.R., and Bennion, Ian

Abstract

A flexible method for fabricating shallow optical waveguides by using femtosecond laser writing of patterns on a metal coated glass substrate followed by ion-exchange is described. This overcomes the drawbacks of low index contrast and high induced stress in waveguides directly written using low-repetition rate ultrafast laser systems. When compared to conventional lithography, the technique is simpler and has advantages in terms of flexibility in the types of structures which can be fabricated.

Published
2008

35. Ultrashort laser pulse cell manipulation using nano- and micro- materials

Author

Schomaker, Markus, primary, Killian, Doreen, additional, Willenbrock, Saskia, additional, Diebold, Eric, additional, Mazur, Eric, additional, Bintig, Willem, additional, Ngezahayo, Anaclet, additional, Nolte, Ingo, additional, Murua Escobar, Hugo, additional, Junghanß, Christian, additional, Lubatschowski, Holger, additional, and Heisterkamp, Alexander, additional

Published
2010
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38. Optical forces in biophotonics: transfection and cell sorting

Author

Ertmer, Wolfgang A., primary, Meyer, Heiko, additional, Lorbeer, Raoul, additional, Bergmann, Gerald, additional, Krämer, Christina, additional, Lubatschowski, Holger, additional, Escoboar, Hugo Murua, additional, Nolte, Ingo, additional, and Heisterkamp, Alexander, additional

Published
2010
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41. Nanoparticle mediated laser cell perforation

Author

Schomaker, Markus, primary, Baumgart, Judith, additional, Ngezahayo, Anaclet, additional, Bullerdiek, Jörn, additional, Nolte, Ingo, additional, Murua-Escobar, Hugo, additional, Lubatschowski, Holger, additional, and Heisterkamp, Alexander, additional

Published
2009
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47. Applications of ultrafast lasers in ophthalmology

Author

Heisterkamp, Alexander, primary, Ripken, Tammo, additional, Oberheide, Uwe, additional, Kermani, Omid, additional, Mamom, Thanongsak, additional, Drommer, Wolfgang, additional, Ertmer, Wolfgang, additional, and Lubatschowski, Holger, additional

Published
2003
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49. Medical and biological applications for ultrafast laser pulses

Author

Lubatschowski, Holger, primary, Heisterkamp, Alexander, additional, Will, Fabian, additional, Singh, Ajoy I., additional, Serbin, Jesper, additional, Ostendorf, Andreas, additional, Kermani, Omid, additional, Heermann, R., additional, Welling, Herbert, additional, and Ertmer, Wolfgang, additional

Published
2003
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