Chemistry: molecular biology and microbiology – Apparatus – Inoculator – streaker – or sampler
Reexamination Certificate
1999-09-15
2001-02-27
Redding, David A. (Department: 1741)
Chemistry: molecular biology and microbiology
Apparatus
Inoculator, streaker, or sampler
C435S309200, C015S236010
Reexamination Certificate
active
06194199
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to collection of cell colonies grown on culture media and, more particularly, is concerned with a cell scraper device having a blade on a pair of handles with pivotal joints connecting the blade to the handles.
2. Description of the Prior Art
Microorganisms are often grown by scientists and others on culture media in petri dishes, culture flasks or the like, for various reasons. Cell colonies grown on culture media are typically grown across a mono-layer of culture medium on a treated plastic surface. The surface is generally treated with a substrate which is usually a chemical coating attached to the plastic. The substrate allows for high densities of cells to grow over a given surface area.
After a predetermined period of time when maximum cell growth is achieved, the cells are ready to be harvested, which involves lifting and removing intact layers of cells from the culture medium. The cells are suspended in the culture medium when they are lifted from the surface of the dish or flask and are decanted into tubes or other containers for further use or analysis. Special care must be taken during this process so that the viability of the cells is maintained and a maximum level of cell recovery is achieved.
A variety of devices have been developed over the years for collecting cell colonies grown on culture media and/or for inoculating culture media with cell colonies. Representative examples of prior art cell colony collection and/or inoculation devices are disclosed in U.S. Pat. No. 4,010,077 to Pardos, U.S. Pat. No. 4,687,746 to Rosenberg et al., U.S. Pat. No. 4,892,831 to Wong, U.S. Pat. No. 5,462,063 to Kist et al. and U.S. Des. Pat. No. 350,603 to Firlik. The Pardos patent discloses a transfer device which includes a plurality of circumferentially spaced fingers extending generally in a common axial direction from a base and diverging from one another. The Rosenberg et al. patent discloses a transfer device which includes a tip at one end of a handle and a loop at the other end of the handle. The Wong patent discloses an inoculating device which includes a loop at one end of a handle and a picker with a pyramidal-shaped head at the other end of the handle. The Kist et al. patent discloses a cell collecting device which includes a handle and a brush head formed of flexible bristles. The bristles can be arranged such that central bristles are surrounded by outer bristles that are shorter and thinner than the central bristles. The bristles can also be arranged in a pattern of concentric circles. The Firlik patent discloses a cell culture scraper which includes a handle and a plate with serrations along an edge thereof at one end of the handle. The fingers of the Pardos device, the tip and loop of the Rosenberg et al. device, the loop and picker of the Wong device, the brush of the Kist et al. device and the plate with serrations of the Firlik device are all adapted to be used to collect a bacteriological specimen or to plate or streak cells on a growth medium. There are other prior art devices known as “cell lifters” or “cell scrapers” which are available to lift or scrape cells from surfaces and into culture media for decanting.
While these prior art cell colony collection and inoculation devices appear to be satisfactory in use for the specific purposes for which they were designed, none of them seem to provide an effective solution for collecting layers of cells which are grown on media inside culture flasks. The problem with these prior art devices is that they do not adequately or easily reach or access the entire interior surface of a tissue culture flask. In addition, their features can cause significant loss of viable cell populations due to damage to cell walls in the process of contacting and scraping the cells from wall surfaces.
Consequently, a need still exists for a device which provides a more effective solution to the aforementioned problems of the prior art devices without introducing any new problems in place thereof.
SUMMARY OF THE INVENTION
The present invention provides a cell scraper device designed to satisfy the aforementioned need. The cell scraper device of the present invention is particularly suited for collecting layers of cells grown inside culture flasks although the device is suitable for other applications as well. The cell scraper device provides adequate and easy access to the culture medium on the entire interior surface of the culture flask while minimizing loss of viable cell populations due to damage to cell walls which may otherwise occur in the process of contacting the cells.
Accordingly, the present invention is directed to a cell scraper device which comprises: (a) a pair of elongated handles for enabling a user to hold and to operate the device, each of the handles having a pair of opposite ends and defining a longitudinal axis extending between the opposite ends, the handles being spaced apart from and disposable along one another and movable in opposite directions along the longitudinal axes; (b) a blade; and (c) means for pivotally joining the blade to a pair of adjacent ones of the opposite ends of the handles such that the blade is pivotally movable between a closed position and an open position relative to the handles upon corresponding movement of the handles in the opposite directions along the longitudinal axes thereof. The blade in the closed position is disposed at an angle of a first size relative to the longitudinal axis of each of the handles along a side of the handles at the pair of adjacent ones of the ends thereof such that the blade and handles are positioned for insertion into and removal from a culture flask through a top opening thereof. The blade in the open position is disposed at another angle of a second size relative to the longitudinal axis of each of the handles which is larger than the angle of the first size such that the blade provides a rake head that can be drawn past a culture medium on an interior surface of the culture flask so as to collect and bring layers of cells growing on the culture medium to an area adjacent to the top opening of the culture flask for decanting the layers of cells from the culture flask.
More particularly, the handles of the device are substantially identical with each handle having a longitudinal length greater than a longitudinal length of the blade. Also, the blade has a substantially flat rectangular configuration and a bottom edge which may be flat, beveled or rounded. Furthermore, the blade is movable between a pair of opposite closed positions and the open position upon corresponding movement of the handles in the opposite directions along the longitudinal axes thereof. The blade in either of the opposite closed positions is disposed at substantially the same acute angles relative to the longitudinal axes of the handles and disposed on either side of the handles.
The means for pivotally joining the blade to the handles of the device preferably comprises a pair of spaced apart pivotal ball joints. Each pivotal ball joint includes a socket mounted to one of the blade and to one of the adjacent ends of pair thereof of the handles, and a ball mounted to the other of the blade and the one of the adjacent ends of the pair thereof of the handles. The balls of the pivotal ball joints are rotatably interfitted with the sockets of the pivotal ball joints such that the blade is pivotally mounted to the pair of adjacent ends of the handles and movable between either closed position and the open position upon the corresponding movement of the handles in the opposite directions along the longitudinal axes thereof. The pivotal joining means, alternatively, can be a pair of living hinge joints pivotally joining the blade to the pair of adjacent ones of the opposite ends of the handles.
These features and advantages of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings wh
Flanagan John K.
Flanagan John R.
Flanagan & Flanagan
Hoffman Michael
Redding David A.
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