Methods and devices for detection of pathogens
In one aspect, a method of detecting a pathogen, e.g., listeria bacterium, chlamydia bacteria, gonorrhea bacteria and/or HPV, in a sample is disclosed, which comprises bringing a sample into contact with a graphene layer functionalized with an antibody exhibiting specific binding to the pathogen, monitoring electrical resistance of said antibody-functionalized graphene layer in response to interaction with said sample, and detecting presence of the pathogen in said sample by detecting a change in said electrical resistance indicative of interaction of the pathogen with said antibody-functionalized graphene layer. For example, a decrease of the electrical resistance of the graphene layer can indicate the presence of the pathogen in the sample under study. In some embodiments, a method according to the present teachings is capable of detecting pathogens, such as listeria bacteria, chlamydia bacteria, gonorrhea bacteria and HPV in a sample at a concentration as low as 4 cfu per 100 grams of a sample.
1. A method of detecting a pathogenic agent in a sample, comprising:
bringing a sample into contact with a graphene layer of a sensor, wherein said graphene layer is functionalized with an antibody exhibiting specific binding affinity to said pathogenic agent, and wherein said sensor further comprises a plurality of conductive pads in electrical contact with said graphene layer to allow measurement of at least one electrical property of the antibody-functionalized graphene layer in response to interaction thereof with said sample, said sensor further comprising a reference electrode disposed in proximity of said antibody-functionalized graphene layer,
applying an AC signal to said reference electrode so as to generate a time-varying electric field extending between said reference electrode and said antibody-functionalized graphene layer,
monitoring said at least one electrical property of said antibody-functionalized graphene layer in response to interaction with said sample, and
detecting presence of said pathogenic agent in said sample by detecting a change in said at least one electrical property indicative of interaction of said pathogenic agent with said antibody-functionalized graphene layer.
2. The method of claim 1 , wherein said time-varying electric field has a frequency in a range of about 1 kHz to about 1 MHz.
3. The method of claim 1 , wherein said graphene layer is disposed on an underlying substrate.
4. The method of claim 3 , wherein said underlying substrate is any of a semiconductor substrate and a glass substrate.
5. The method of claim 3 , wherein a microfluidic structure is coupled to said underlying substrate, said microfluidic structure having at least one reservoir and a fluidic channel fluidly coupled to said at least one reservoir, said fluidic channel being in fluid communication with at least a portion of said graphene layer, and said at least one reservoir being configured for receiving a sample.
6. The method of claim 1 , wherein said pathogenic agent comprises listeria bacteria.
7. The method of claim 1 , wherein said pathogenic agent comprises chlamydia bacteria.
8. The method of claim 1 , wherein said pathogenic agent comprises gonorrhea bacteria.
9. The method of claim 1 , wherein said pathogenic agent comprises HPV.
10. The method of claim 1 , wherein said at least one electrical property includes an electrical resistance.
11. The method of claim 1 , wherein said time-varying electric field has a frequency in a range of about 10 kHz to about 1 MHz.
12. The method of claim 1 , wherein said time-varying electric field has a frequency in a range of about 10 kHz to about 500 KHz.
13. The method of claim 1 , wherein said time-varying electric field has a frequency in a range of about 20 kHz to about 400 KHz.
14. The method of claim 1 , wherein said time-varying electric field has a frequency in a range of about 30 kHz to about 300 KHz.
15. The method of claim 1 , wherein said time-varying electric field has a frequency in a range of about 40 kHz to about 200 KHz.
16. The method of claim 1 , wherein said reference electrode is disposed at a distance in a range of about 50 microns to about 2 mm from said antibody-functionalized graphene layer.
17. The method of claim 1 , wherein a DC offset is further applied to said reference electrode.
18. The method of claim 1 , wherein said at least one electrical property is measured based on a four-point measurement technique using said plurality of conductive pads that are in electrical contact with said graphene layer.