Limits...
Biconically tapered fiber optic probes for rapid label-free immunoassays.

Miller J, Castaneda A, Lee KH, Sanchez M, Ortiz A, Almaz E, Almaz ZT, Murinda S, Lin WJ, Salik E - Biosensors (Basel) (2015)

Bottom Line: Hydrofluoric acid treatment makes the sensitive region thinner to enhance sensitivity, which we confirmed by experiments and simulations.The limit of detection for the sensor was estimated to be less than 50 ng/mL.Utilization of the rate of the sensor peak shift within the first few minutes of the antibody-antigen reaction is proposed as a rapid protein detection method.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Astronomy, University of California, Los Angeles, 475 Portola Plaza, Los Angeles, CA 90095, USA. johnmiller@physics.ucla.edu.

ABSTRACT
We report use of U-shaped biconically tapered optical fibers (BTOF) as probes for label-free immunoassays. The tapered regions of the sensors were functionalized by immobilization of immunoglobulin-G (Ig-G) and tested for detection of anti-IgG at concentrations of 50 ng/mL to 50 µg/mL. Antibody-antigen reaction creates a biological nanolayer modifying the waveguide structure leading to a change in the sensor signal, which allows real-time monitoring. The kinetics of the antibody (mouse Ig-G)-antigen (rabbit anti-mouse IgG) reactions was studied. Hydrofluoric acid treatment makes the sensitive region thinner to enhance sensitivity, which we confirmed by experiments and simulations. The limit of detection for the sensor was estimated to be less than 50 ng/mL. Utilization of the rate of the sensor peak shift within the first few minutes of the antibody-antigen reaction is proposed as a rapid protein detection method.

Show MeSH
Sensor interrogation system. Amplified spontaneous emission from the semiconductor optical amplifier is used as the broadband light source in the 1450–1600 nm wavelength range. Data acquired from the optical spectrum analyzer was saved in a PC using Labview.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4493543&req=5

biosensors-05-00158-f002: Sensor interrogation system. Amplified spontaneous emission from the semiconductor optical amplifier is used as the broadband light source in the 1450–1600 nm wavelength range. Data acquired from the optical spectrum analyzer was saved in a PC using Labview.

Mentions: Figure 2 shows our setup for testing the functionalized sensors. Amplified spontaneous emission from a semiconductor optical amplifier (SOA) was used as a broadband light source (1450–1600 nm). A 1 × 5 optical switch allowed us to measure the source and the sensor response ~5 s apart and up to 4 different sensors can be automatically interrogated with one channel reserved for reference measurement to account for any fluctuations in the source power. In actual tests, we usually interrogated three sensors simultaneously while immersed in each solution. Every ~20 s a sensor spectrum was recorded. Five-minute immersions in PBST served as baseline measurements between all other solutions. Fifteen-minute immersions in BSA/PBST served as a negative control for non-specific binding, both before and after testing in anti-IgG. The sensing of the target protein (anti-IgG) to the IgG-coated sensors was measured for at least 30 min. Throughout the entire measurement, the solutions were kept within a solid aluminum heat block that was immersed in a water bath to keep the temperature stable. A temperature probe, which was kept adjacent to the heat block within the water bath, was used to monitor temperature for every measurement. In addition to all control measurements, we collected the sensor transmission spectra for at least 1 h in the wavelength range of 1475–1575 nm with resolution at 1.0 nm, which amounts to at least 200 spectra to be analyzed.


Biconically tapered fiber optic probes for rapid label-free immunoassays.

Miller J, Castaneda A, Lee KH, Sanchez M, Ortiz A, Almaz E, Almaz ZT, Murinda S, Lin WJ, Salik E - Biosensors (Basel) (2015)

Sensor interrogation system. Amplified spontaneous emission from the semiconductor optical amplifier is used as the broadband light source in the 1450–1600 nm wavelength range. Data acquired from the optical spectrum analyzer was saved in a PC using Labview.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493543&req=5

biosensors-05-00158-f002: Sensor interrogation system. Amplified spontaneous emission from the semiconductor optical amplifier is used as the broadband light source in the 1450–1600 nm wavelength range. Data acquired from the optical spectrum analyzer was saved in a PC using Labview.
Mentions: Figure 2 shows our setup for testing the functionalized sensors. Amplified spontaneous emission from a semiconductor optical amplifier (SOA) was used as a broadband light source (1450–1600 nm). A 1 × 5 optical switch allowed us to measure the source and the sensor response ~5 s apart and up to 4 different sensors can be automatically interrogated with one channel reserved for reference measurement to account for any fluctuations in the source power. In actual tests, we usually interrogated three sensors simultaneously while immersed in each solution. Every ~20 s a sensor spectrum was recorded. Five-minute immersions in PBST served as baseline measurements between all other solutions. Fifteen-minute immersions in BSA/PBST served as a negative control for non-specific binding, both before and after testing in anti-IgG. The sensing of the target protein (anti-IgG) to the IgG-coated sensors was measured for at least 30 min. Throughout the entire measurement, the solutions were kept within a solid aluminum heat block that was immersed in a water bath to keep the temperature stable. A temperature probe, which was kept adjacent to the heat block within the water bath, was used to monitor temperature for every measurement. In addition to all control measurements, we collected the sensor transmission spectra for at least 1 h in the wavelength range of 1475–1575 nm with resolution at 1.0 nm, which amounts to at least 200 spectra to be analyzed.

Bottom Line: Hydrofluoric acid treatment makes the sensitive region thinner to enhance sensitivity, which we confirmed by experiments and simulations.The limit of detection for the sensor was estimated to be less than 50 ng/mL.Utilization of the rate of the sensor peak shift within the first few minutes of the antibody-antigen reaction is proposed as a rapid protein detection method.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Astronomy, University of California, Los Angeles, 475 Portola Plaza, Los Angeles, CA 90095, USA. johnmiller@physics.ucla.edu.

ABSTRACT
We report use of U-shaped biconically tapered optical fibers (BTOF) as probes for label-free immunoassays. The tapered regions of the sensors were functionalized by immobilization of immunoglobulin-G (Ig-G) and tested for detection of anti-IgG at concentrations of 50 ng/mL to 50 µg/mL. Antibody-antigen reaction creates a biological nanolayer modifying the waveguide structure leading to a change in the sensor signal, which allows real-time monitoring. The kinetics of the antibody (mouse Ig-G)-antigen (rabbit anti-mouse IgG) reactions was studied. Hydrofluoric acid treatment makes the sensitive region thinner to enhance sensitivity, which we confirmed by experiments and simulations. The limit of detection for the sensor was estimated to be less than 50 ng/mL. Utilization of the rate of the sensor peak shift within the first few minutes of the antibody-antigen reaction is proposed as a rapid protein detection method.

Show MeSH