Plasma-mediated ablation makes use of high energy laser pulses to ionize molecules within the first few femtoseconds of the pulse. This process leads to a submicrometer-sized bubble of plasma that can ablate tissue with negligible heat transfer and collateral damage to neighboring tissue. We review the physics of plasma-mediated ablation and its use as a tool to generate targeted insults at the subcellular level to neurons and blood vessels deep within nervous tissue. Illustrative examples from axon regeneration and microvascular research illustrate the utility of this tool. We further discuss the use of ablation as an integral part of automated histology.The classic application of light microscopy to studies in physiology is observational; the illumination is too weak to affect the preparation. Yet the focused illumination in light microscopy can be strong enough to influence the chemical and physical structure of the sample and thus constitutes a means to manipulate living preparations. At the level of molecular studies, optical tweezers allow the application of forces and torques to individual molecules attached to dielectric microspheres [1,2]. At the level of subcellular organelles, photo-switching of fluorescent labels can toggle molecules between active and inactive states [3,4], while photo-activation of ions and small molecules provide a means to alter the chemical milieu within diffraction-limited volumes [5]. At the level of cells, photoswitching of bound ligands can lead to agonist binding [6], while light-activated membrane channels and pumps provide a means to change the electrical potential across cell membranes [7] Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. [8,9]. This last application is the subject of this review. NIH Public Access Principles and practice of plasma-mediated ablationPulsed laser systems easily achieve the high instantaneous peak powers necessary to induce nonlinear absorption, while maintaining sufficiently low average powers to avoid linear heating of the sample. This enables nonlinear imaging of biological structure and function [10], including two-photon laser scanning microscopy [11][12][13], second [14][15][16] and third harmonic [17][18][19][20][21][22] imaging, and coherent anti-stokes Raman spectroscopy [23,24]. The critical issue, especially for in vivo imaging, is that the nonlinear absorption allows excitation to occur only in the focus volume so that all excited molecules are a potential source of signal. Thus optical sectioning is performed solely by the excitation beam. Fluorescently labeled cells deep below th...

An oxidized porous Si interferometer was used to measure binding of immunoglobulin G (IgG) to an immobilized protein A capture probe. Protein A was non‐covalently immobilized on a thermally oxidized porous Si (PSiO2) sample and exposed to IgG originating from different species. The resulting order of IgG affinity toward the protein A‐coated surface (human > rabbit ≫ sheep IgG) agrees with previous inhibition studies for protein A/IgG binding. No signal change was observed when a protein A coated sample was exposed to bovine serum albumin (BSA), demonstrating that the adsorbed sensing layer sufficiently coats the PSiO2 surface to prevent non‐specific binding. This strategy is excellent for qualitative measurements of protein binding affinity because it is label‐free, requires minimal sample preparation, and can be implemented using an inexpensive CCD‐based spectrometer coupled to a tungsten lamp. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

We present a method for achieving temporally and spatially precise photoactivation of neurons without the need for genetic expression of photosensitive proteins. Our method depends upon conduction of thermal energy via absorption by a dye or carbon particles and does not require the presence of voltage-gated channels to create transmembrane currents. We demonstrate photothermal initiation of action potentials in Hirudo verbana neurons and of transmembrane currents in Xenopus oocytes. Thermal energy is delivered by focused 50 ms, 650 nm laser pulses with total pulse energies between 250 and 3500 µJ. We document an optical delivery system for targeting specific neurons that can be expanded for multiple target sites. Our method achieves photoactivation reliably (70 -90% of attempts) and can issue multiple pulses (6-9) with minimal changes to cellular properties as measured by intracellular recording. Direct photoactivation presents a significant step towards all-optical analysis of neural circuits in animals such as Hirudo verbana where genetic expression of photosensitive compounds is not feasible.Comments: 10 pages with 4 figures.

Absolute calibration of optical tweezers including aberrations Appl. Phys. Lett. 100, 131115 (2012); 10.1063/1.3699273 Comment on "Theoretical analysis of numerical aperture increasing lens microscopy" [J. Appl. Phys.97, 053105 (2005)] J.

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