Cell grabber with unitary construction

#The present invention relates to a biological specimen holder used together with an adhesive or attachment factor in order to secure the specimen for tensile measurements. In a preferred embodiment, the holder has a concave bonding surface defining a cylindrical section profile which has a radius of curvature in the range of from 20 to 50 microns so as to be suitable to grab a single cell.

#Accurate measurements of cellular mechanical properties are critical to understand a cell's biological response to its environment. The quality of mechanical measurements depends greatly on the attachment method of the apparatus to the cell specimen. Attachment methods for single-cell specimens are much more tedious than those used on multi-cell specimens. There are no available external attachment locations forcing the apparatus to attach directly to the cell membrane. Therefore, the attachment method must not disturb the specimen while still providing strong enough attachment strength to allow for the application of large forces to the specimen. There have been a number of proposed attachment methods including wrapping, glass micro-needles, and suction micropipettes. Reference is made to the following: Fabiato, A., and F. Fabiato, 1975, “Contractions Induced by a Calcium-Triggered Release of Calcium From the Sarcoplasmic Reticulum of Single Skinned Cardiac Cells . . . ” The Journal of Physiology 249 (3) (August): 469-495; Iribe, Gentaro, Michiel Helmes, and Peter Kohl. 2006, “Force-Length Relations in Isolated Intact Cardiomyocytes Subjected to Dynamic Changes in Mechanical Load . . . ” American Journal of Physiology. Heart and Circulatory Physiology 292 (3) (March): H1487-97, doi:10.1152/ajpheart.00909.2006; Tajitsu, Y. 2008 “Piezoelectricity of Chiral Polymeric Fiber and Its Application in Biomedical Engineering” IEEE Transactions on Ultrasonicsm, Ferroelectronics, and Frequency Control 55 (5) (May): 1000-1008. doi 10.1109/TUFFC.2008.746; Brady, A. J., 1991, “Mechanical Properties of Isolated Cardiac Myocytes.” Physiological Reviews 71 (2) (April): 413-428; Prosser, Benjamin L., Christopher W. Ward, and W. J. Lederer, 2011, “X-ROS Signaling: Rapid Mechano-Chemo Transduction in Heart.” Science (New York, N.Y.) 333 (6048) (September 9): 1440-1445, doi:10.1126/science.1202768; Krulevitch et al.; Cohen, A. L., “Medical Devices and EFAB Methods and Apparatus for Producing Them” 2005; Publication No. US2005/0121411; as well as United State Patent Publication US 2012/0096955 of Guth et al. which relates to an S I Instruments Brochure, undated. The cell micrograbber is described in the brochure as a hollow metal tube with two tapered tweezer tips of custom design which in a closed position has a thin, stainless steel rod running through the center of it. When the rod is pushed towards the tip using the control box, the fingers of the tip open to allow the tweezers to grasp a muscle fiber. As the stainless steel rod retracts, the tweezers close and hold the fiber. The device is relatively complex to fabricate and operate and has a limited range of utility in terms of force levels.

#As will be appreciated from the foregoing, auxotonic, isometric and isotonic force measurement systems have all been employed to measure cell characteristics in various environments, employing various cell attachment mechanisms and devices of various complexity.

#The invention is described in detail below in connection with numerous embodiments and in connection with the attached Figures wherein like numerals and letters designate like parts and features. In the Figures:

#FIG. 1 is a schematic side view in elevation and section of a cell grabber of the invention bonded to a single cell;

#FIG. 2 is a schematic top view of a cell grabber of the invention bonded to a single cell;

#The invention is described in detail below in connection with the Figures for purposes of illustration, only. The invention is defined in the appended claims. Terminology used throughout the specification and claims herein are given their ordinary meanings as supplemented by the discussion immediately below.

#“Adhesive” refers to attachment factors now used or hereinafter developed which are suitable for adhering a cell or tissue to a substrate for testing. Suitable attachment factors include polylysine/fibronectin coatings, or for example, a collagen based attachment factor. Especially preferred are adhesives of the class MYOTAK® biocompatible adhesives which are described in United States Patent Application Publication No. 2012/0034620 of Ward et al., the disclosure of which is incorporated by reference. Adhesives also include extracellular matrix proteins with or without bond strength agents or aggregates. An adhesive is considered biocompatible if contact with the adhesive for 60 minutes is not lethal to the cell.

#As used herein, “aggregate” refers to any composition added to the bio-adhesive composition which results in an increased stability and a larger surface area for attachment. Known aggregates include alumina silicate or diamond powder, and range from approximately 0.1 microns 10 microns or for example from approximately 0.1 micron to 3 microns in diameter depending on the apparatus interface and the type of specimen.