| Popis: |
A biosensor based on long period grating (LPG) technology has been used to demonstrate the detection of large molecules (proteins) and small molecules (pesticides). The LPG sensor is a spectral loss optical fiber based system that provides direct detection of large molecules, by using an antigen or antibody modified hydrogel, without the need for secondary amplification. The binding of the specific target results in a mass increase that produces a localized refractive index change around the LPG region and thus a spectral shift in the observed wavelength loss band. The magnitude of the observed shift can be correlated to target concentration. The HIV protein p24 was directly detected at 1 ng/mL with a specific signal that was 5 - 7 times that of the system noise. A direct and indirect competitive assay was demonstrated with the target atrazine. The sensitivity of the two competitive assay formats was in the range of 10 - 50 ng/mL. In all three-assay examples, the biosensor was regenerated by treatment with 50 mM HCl and reused. The LPG biosensor offers speed (results in less than five minutes), versatility, reuse, specificity and sensitivity. |
