The shift in the SPR angle check details is recorded as a function of time in the sensorgram. At equilibrium, the fraction of the surface that is covered reaches a steady state and this equilibrium surface coverage (θ eq)SP is given by the Langmuir absorption isotherm,

[40] Figure 3 Time course for value of SPR sensorgrams in analysis of interaction that involves bimolecular association and dissociation. (3) where the Langmuir absorption coefficient (K abs) is defined as K abs  = k a /k d. Based on Fresnel’s AZD5153 Equations, given the reflection coefficient, the SP wave vectors for the Au-GOS-BSA boundary, and the coupler matching condition of the SPR are as given by Equation 4. (4) where K x is the wave-vector parallel to the surface form which light is reflected, K 0 is the wave-vector in a vacuum, and K sp is the SP wave-vector that is parallel to the interfaces between the metal and the dielectric. θ eq is the SPR angle at equilibrium,

ε p is the refractive index of the prism, and ε m and ε d are the metal and dielectric constants of the sample, respectively. Results and discussion Analysis of sensitivity of interaction between GOS and BSA Two-dimensional GOS surfaces can detect a large area, in which the evanescent field decays exponentially with the distance beyond 600 nm from the metal. Figure 4 https://www.selleckchem.com/products/qnz-evp4593.html shows the interaction of a GOS with BSA. GOS performs a spacing function BSA and GOS, which increases the accessibility of the immobilized GOS. Figure 4 Florfenicol GOS-BSA interaction. GOS is immobilized

on a planar immobilization film, which is a few tens of nanometers thick, and is readily accessible by analytic BSA protein with which it undergoes specific interactions. Kinetic analysis of interaction between GOS and BSA Molecular kinetics of the interactions of the three sensor films and the protein are analyzed. Figure 5 presents the SPR sensorgrams (BI-3000G SPR system) of a Au-MOA film (conventional SPR chip) (Figure 5a), a Au-Cys-GOS film (GOS film-based SPR chip) (Figure 5b), and a Au-ODT-GOS film (ODT-based GOS film-based SPR chip) (Figure 5c), in response to solutions of BSA with a concentration of 100 μg/ml in phosphate buffered saline (PBS) buffer. The affinity constants (K A) of 100 μg/ml BSA on the ODT-based GOS film-based SPR chip, the conventional SPR chip, and the GOS film-based SPR chip were 2.6 × 106 M-1, 15.67 × 106 M-1, and 80.82 × 106 M-1, respectively. The ratio of the affinities of the ODT-based GOS film-based SPR chip, conventional chip, and GOS film SPR chip was 1:6:31 times. The results demonstrate that this Cys-modified Au surface excellently immobilized a GOS film in an SPR chip. Figure 5 SPR sensorgrams obtained in response to BSA, at concentration of 100 μg/ml, flowing over surfaces of films.