Methods and apparatus for detecting bacteria using an acoustic device
First Claim
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1. A method for detecting bacteria in a sample, the method comprising the steps of:
- a) introducing a fluid comprising a sample and a plurality of magnetic particles coated with a first capture agent capable of binding the bacteria into a fluid chamber, wherein at least one surface of the fluid chamber comprises a flexural plate wave device having a second capture agent capable of binding the bacteria, wherein the flexural plate wave device comprises a membrane that is capable of vibrating, and wherein the second capture agent is bound to the membrane;
b) applying a retractable source of magnetic flux positioned external to the fluid chamber close to the membrane to create a significant magnetic field gradient at a surface of the membrane to attract magnetic particles in the fluid toward the membrane;
c) monitoring a first signal output by said flexural plate wave device, wherein the first signal output is monitored in the presence of a magnetic flux;
d) after removing the retractable source of magnetic flux, flowing a solution through the fluid chamber to remove magnetic particles not bound to the membrane;
e) monitoring a second signal output by said flexural plate wave device, wherein the second signal output is monitored in the absence of the magnetic flux; and
f) comparing the first and the second signal output to a control signal, thereby detecting bacteria in the sample.
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Abstract
Methods for detecting bacteria are provided. A plurality of particles, each of which is coated with a capture agent having an affinity for the bacteria, is combined with the sample to form a plurality of analyte-particle complexes. The system also includes a transport arrangement for transporting the sample to the sensor surface, and optionally a magnetic field inducing structure constructed and arranged to establish a magnetic field at and adjacent to the sensor surface. The resonant sensor produces a signal corresponding to an amount of analyte-particle complexes that are bound to the sensor surface.
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Citations
30 Claims
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1. A method for detecting bacteria in a sample, the method comprising the steps of:
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a) introducing a fluid comprising a sample and a plurality of magnetic particles coated with a first capture agent capable of binding the bacteria into a fluid chamber, wherein at least one surface of the fluid chamber comprises a flexural plate wave device having a second capture agent capable of binding the bacteria, wherein the flexural plate wave device comprises a membrane that is capable of vibrating, and wherein the second capture agent is bound to the membrane; b) applying a retractable source of magnetic flux positioned external to the fluid chamber close to the membrane to create a significant magnetic field gradient at a surface of the membrane to attract magnetic particles in the fluid toward the membrane; c) monitoring a first signal output by said flexural plate wave device, wherein the first signal output is monitored in the presence of a magnetic flux; d) after removing the retractable source of magnetic flux, flowing a solution through the fluid chamber to remove magnetic particles not bound to the membrane; e) monitoring a second signal output by said flexural plate wave device, wherein the second signal output is monitored in the absence of the magnetic flux; and f) comparing the first and the second signal output to a control signal, thereby detecting bacteria in the sample.
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2. The method of claim 1, wherein prior to being introduced into the fluid chamber, said plurality of particles has been exposed to the sample.
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3. The method of claim 1, wherein the sample has been introduced into the fluid chamber prior to introducing the plurality of particles.
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4. The method of claim 1, wherein the sample is selected from the group consisting of sputum, nasal swab, blood, plasma, serum, cerebrospinal fluid, urine and fecal matter.
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5. The method of claim 1, wherein the sample is selected from poultry wash and meat.
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6. The method of claim 1, wherein the bacteria is selected from the group consisting of pathogenic E. coli., Neisseria gonorrhoeae, Borrelia burgdorferi, Vibrio cholerae, Corynebacterium diphtheriae, Salmonella typhimurium, Salmonella enterica, and Helicobacter pylori.
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7. The method of claim 1, wherein the control signal is obtained in the absence of sample.
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8. The method of claim 1, wherein the control signal is a standard curve.
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9. The method of claim 1, wherein said second capture agent capable of binding the bacteria is indirectly bound to said surface.
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10. The method of claim 9, wherein said surface is coated with a first member of a binding pair, and said second capture agent is bound to a second member of the binding pair.
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11. The method of claim 10, wherein the first member of the binding pair is biotin.
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12. The method of claim 1, wherein the first or second capture agent is an antibody.
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13. The method of claim 1, wherein the first capture agent and the second capture agent are the same capture agent.
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14. The method of claim 1, wherein the sample comprises meat or poultry wash and wherein the method further comprises assessing food safety by detecting bacteria in a sample.
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15. A method for assessing food safety by detecting bacteria in a sample, the method comprising the steps of:
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a) introducing a fluid comprising a sample and a plurality of magnetic particles coated with a first capture agent capable of binding the bacteria into a fluid chamber, wherein at least one surface of the fluid chamber comprises a flexural plate wave device having a second capture agent capable of binding the bacteria, wherein the flexural plate wave device comprises a membrane that is capable of vibrating, and wherein the second capture agent is bound to the membrane; b) applying a retractable source of magnetic flux positioned external to the fluid chamber close to the membrane to create a significant magnetic field gradient at a surface of the membrane to attract magnetic particles in the fluid toward the membrane; c) monitoring a first signal output by said flexural plate wave device, wherein the first signal output is monitored in the presence of a magnetic flux; d) after removing the retractable source of magnetic flux, flowing a solution through the fluid chamber to remove magnetic particles not bound to the membrane; e) monitoring a second signal output by said flexural plate wave device, wherein the second signal output is monitored in the absence of the magnetic flux; and f) comparing the first and the second signal output to a control signal, thereby detecting bacteria in the sample.
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16. The method of claim 15, wherein prior to being introduced into the fluid chamber, said plurality of particles has been exposed to the sample.
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17. The method of claim 15, wherein the sample has been introduced into the fluid chamber prior to introducing the plurality of particles.
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18. The method of claim 15, wherein the sample is selected from the group consisting of blood, plasma, serum, cerebrospinal fluid, urine and fecal matter.
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19. The method of claim 15, wherein the sample is selected from poultry wash and meat.
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20. The method of claim 15, wherein the bacteria is selected from the group consisting of pathogenic E. coli, Neisseria gonorrhoeae, Borrelia burgdorferi, Vibrio cholerae, Corynebacterium diphtheriae, Salmonella typhimurium, Salmonella enterica, and Helicobacter pylori.
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21. The method of claim 15, wherein the control signal is obtained in the absence of sample.
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22. The method of claim 15, wherein the control signal is a standard curve.
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23. The method of claim 15, wherein said second capture agent capable of binding the bacteria is indirectly bound to said surface.
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24. The method of claim 23, wherein said surface is coated with a first member of a binding pair, and said second capture agent is bound to a second member of the binding pair.
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25. The method of claim 24, wherein the first member of the binding pair is biotin.
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26. The method of claim 15, wherein the first or second capture agent is an antibody.
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27. The method of claim 11, wherein the second member of the binding pair is a derivative of avidin.
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28. The method of claim 24, wherein the second member of the binding pair is a derivative of avidin.
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29. The method of claim 1, wherein a fluid flows across the membrane during one or more of steps a), b), c) and e).
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30. The method of claim 15, wherein a fluid flows across the membrane during one or more of steps a), b), c) and e).
Specification