News Column

"Analyte Permeable Membrane Systems for Oxidative and Optical Stability" in Patent Application Approval Process

July 22, 2014



By a News Reporter-Staff News Editor at Life Science Weekly -- A patent application by the inventors Emken, Jeremy (Germantown, MD); Huffstetler, Philip (Germantown, MD); Whitehurst, Todd (Germantown, MD), filed on December 27, 2013, was made available online on July 10, 2014, according to news reporting originating from Washington, D.C., by NewsRx correspondents (see also Senseonics, Incorporated).

This patent application is assigned to Senseonics, Incorporated.

The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention relates generally to sensors for implantation or insertion within a living animal and measurement of a concentration of an analyte in a medium within the living animal. Specifically, the present invention relates to sensors having a membrane over an indicator element on the surface of the sensor body.

"A sensor may include an indicator element, such as, for example, indicator molecules embedded or polymerized in or onto a polymer graft (i.e., layer or matrix). For example, in an implantable fluorescence-based glucose sensor, fluorescent indicator molecules may reversibly bind glucose and, when illuminated with excitation light (e.g., light having a wavelength of approximately 378 nm), emit an amount of light (e.g., light in the range of 400 to 500 nm) that depends on whether glucose is bound to the indicator molecule.

"If a sensor is implanted in the body of a living animal, the animal's immune system begins to attack the sensor. For instance, if a sensor is implanted in a human, white blood cells attack the sensor as a foreign body, and, in the initial immune system onslaught, neutrophils are the primary white blood cells attacking the sensor. Macrophages and giant cells may further attack the sensor. The defense mechanism of neutrophils and other white blood cells includes the release of highly oxidative substances known as reactive oxygen species (ROS), such as hydrogen peroxide (H.sub.2O.sub.2), hydroxyl radical (OH.), hypochlorite (OCl.sup.-), peroxynitrite (OONO.sup.-), and superoxide (O.sub.2).

"ROS, such as hydrogen peroxide, may degrade indicator molecules. For instance, in indicator molecules having a boronate group, hydrogen peroxide may degrade the indicator molecules by oxidizing the boronate group, thus disabling the ability of the indicator molecule to bind glucose.

"In addition, if the sensor is an optical sensor, light (e.g., excitation light, fluorescent light emitted by the indicator molecules) from the sensor may pass through the indicator element or other transparent portions of the sensor. If the sensor has been implanted in animal tissue, the light may be reflected by the tissue or may cause the tissue to fluoresce and return light at a different wavelength. The reflected and fluoresced light from the tissue may return through the indicator element or other transparent part of the sensor and may be received by one or more light detectors (e.g., photodiodes) of the sensor. This results in noise in the signals received by the light detectors.

"Moreover, if the animal (e.g., a human patient) is in a brightly lit area, then the light may pass through the patient's skin and be received by the light detectors of the sensor. This could also introduce noise into the signals received by the light detectors. Thus, erroneous sensor readings may occur because light detectors in an implanted sensor may receive additional signals unrelated to the analyte concentration.

"There is presently a need in the art for improvements in optical sensor isolation and reducing indicator element degradation."

In addition to the background information obtained for this patent application, NewsRx journalists also obtained the inventors' summary information for this patent application: "The present invention overcomes the disadvantages of prior systems by providing, among other advantages, improved optical isolation and/or reduced indicator element degradation while still allowing an analyte of interest to reach the indicator element.

"One aspect of the present invention provides a sensor that may be used for in vivo detection of the presence, amount, and/or concentration of an analyte in a medium within a living animal. The sensor may include a sensor housing, an indicator element embedded within and/or covering at least a portion of the sensor housing, and a membrane over at least a portion of the indicator element. The indicator element may include indicator molecules.

"In some embodiments, the membrane may have pores configured to substantially prevent white blood cells from passing through the membrane but to permit the analyte to pass through the membrane. The membrane may be opaque. In some embodiments, the membrane may catalyze degradation of ROS, such as hydrogen peroxide, and reduce deterioration of the indicator element. The membrane may comprise a hydrophilic or hydrophobic membrane material.

"In some embodiments, the membrane is a porous, opaque diffusion membrane covering at least a portion of the housing and the graft, and the membrane may be configured to substantially prevent white blood cells from passing through the membrane and permit an analyte of interest to pass through the membrane to the indicator element and to substantially prevent transmission of light of at least a specified wavelength or range of wavelengths through the membrane. The diffusion membrane may comprise an opaque or light absorbing colorant.

"Further variations encompassed within the systems and methods are described in the detailed description of the invention below.

BRIEF DESCRIPTION OF THE DRAWINGS

"The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various, non-limiting embodiments of the present invention. In the drawings, like reference numbers indicate identical or functionally similar elements.

"FIG. 1 is a schematic view of a sensor system, which includes an implantable sensor and a sensor reader, embodying aspects of the present invention.

"FIG. 2 illustrates a perspective view of a sensor embodying aspects of the present invention.

"FIG. 3 illustrates an exploded view of a sensor embodying aspects of the present invention.

"FIGS. 4 and 5 illustrate perspective views of sensor components within the sensor body/shell/capsule of a sensor embodying aspects of the present invention.

"FIG. 6 illustrates a side view of a sensor embodying aspects of the present invention.

"FIG. 7 illustrates a cross-sectional end view of a sensor embodying aspects of the present invention.

"FIG. 8 illustrates a cross-sectional side view of a sensor in operation in accordance with an embodiment of the present invention.

"FIGS. 9 and 10 illustrate a side view of a sensor, without and with a membrane over the indicator element, respectively, in accordance with an embodiment of the present invention.

"FIGS. 11 and 12 illustrate a cross-sectional view of a sensor in accordance with an embodiment of the present invention.

"FIG. 13 is a perspective view of an alternate embodiment of a sensor embodying aspects of the present invention and comprising an opaque diffusion membrane substantially, or totally, covering the housing of a sensor.

"FIG. 14 is a transverse cross-section of the sensor and opaque diffusion membrane along the line XIV-XIV in FIG. 13.

"FIG. 15 is an alternate embodiment of a sensor covered with an opaque diffusion membrane."

URL and more information on this patent application, see: Emken, Jeremy; Huffstetler, Philip; Whitehurst, Todd. Analyte Permeable Membrane Systems for Oxidative and Optical Stability. Filed December 27, 2013 and posted July 10, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=2045&p=41&f=G&l=50&d=PG01&S1=20140703.PD.&OS=PD/20140703&RS=PD/20140703

Keywords for this news article include: Gases, Anions, Elements, Chemistry, Blood Cells, Electrolytes, Free Radicals, Hydrogen Peroxide, Inorganic Chemicals, Reactive Oxygen Species, Senseonics Incorporated.

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


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Source: Life Science Weekly


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