Optical fiber probe

1. A sensor comprising:

an optical fiber having a probe region having at least one curved portion configured to enhance penetration of evanescent waves; and

one or more nanoparticles in optical communication with the probe region, and configured to enhance localized surface plasmon resonance,

wherein at least a part of the probe region further comprises at least a first substantially straight portion, coated with nanoparticles, configured for exposure to a sample and a second substantially straight portion configured to avoid exposure to the sample, and

wherein the at least one curved portion comprises a coiled fiber.

2. The sensor of claim 1 , further comprising an optical setup configured to detect absorbance of radiation in the probe region.

3. The sensor of claim 2 , wherein the optical setup comprises a radiation source at one end of the probe and a detector at the other end of the probe.

4. The sensor of claim 1 , wherein at least a part of the probe region comprises a receptor that is configured to bind to an analyte in a sample.

5. The sensor of claim 1 , wherein the probe region is configured for exposure to a sample.

6. The sensor of claim 1 , wherein at least a part of the curved portion is substantially U or V shaped.

7. The sensor of claim 1 , further comprising a flow cell configured to contain a sample and to surround at least a part of the curved portion.

8. The sensor of claim 7 , wherein the flow cell has a volume of greater than zero microliter and less than 100 microliter.

9. The sensor of claim 1 , wherein the sensor is configured to detect immobilization of bioreceptors and/or immunocomplex formation.

10. The sensor of claim 1 , wherein the sensor is configured to detect a presence of an analyte in the sample and to detect a concentration of the analyte in the sample.

11. The sensor of claim 1 , wherein the nanoparticles comprise a metal exhibiting the surface plasmon resonance.

12. The sensor of claim 1 , wherein the at least one curved portion has a bend radius of about 0.5 mm to about 1.75 mm.

13. The sensor of claim 1 , wherein the one or more nanoparticles in optical communication with the probe region comprise at least one of metal-coated silica and metal-coated polystyrene.

14. The sensor of claim 1 , wherein the one or more nanoparticles in optical communication with the probe region comprise at least one of nanostars, nanorice, and nanorods.

15. A method of making an optical sensor, the method comprising:

bending a portion of an optical fiber to form a bent optical fiber having a curved portion, a first substantially straight portion, and a second substantially straight portion;

forming a coil in the curved portion of the bent optical fiber;

coating nanoparticles on at least the first substantially straight portion of the bent optical fiber to form a probe region; and

configuring the second substantially straight portion of the bent optical fiber to avoid exposure to the sample.

16. The method of claim 15 , further comprising connecting an optical setup configured to detect a difference in refractive index of a sample and a reference material, wherein the optical setup is configured to further detect absorbance of radiation in the bent optical fiber.

17. The method of claim 16 , wherein the optical setup comprises a radiation source connected to one end of the bent optical fiber and a spectrophotometer at the other end of the bent optical fiber.

18. The method of claim 15 , further comprising coating at least a part of the probe region with a receptor that binds to an analyte in the sample.

19. A sensing system comprising:

a radiation source to provide radiation;

an optical fiber to guide the radiation through a sample, the optical fiber comprising a probe region having:

a first substantially straight portion to be exposed to the sample;

a curved portion comprising a coiled fiber to enhance penetration of evanescent waves into the sample; and

a second substantially straight portion configured to avoid exposure to the sample;

one or more nanoparticles, in optical communication with the first substantially straight portion and the curved portion, to enhance localized surface plasmon resonance between the radiation transmitted through the probe region and the sample; and

a spectrometer, in optical communication with the optical fiber, to detect a change in an absorbance spectrum of the radiation transmitted through the probe region due to the localized surface plasmon resonance between the radiation transmitted through the probe region and the sample.