Spectroscopic investigation of a red emitting dye in the companionship of serum albumins and cucurbit[7]uril

In this work we have examined the photophysics and binding interaction of a red emitting molecule nile blue A (NBA) with bovine serumalbumin (BSA) and human serumalbumin (HSA) along with gradual addition of cucurbit[7]uril (CB7) by employing various spectroscopic methods. The change in absorption and emission maxima position of NBA in the presence of BSA or HSA as well as in the presence and absence of CB7 strongly suggest strong interaction between the species in the solution. The binding constant as calculated for NBA-HSA and NBA-BSA indicates that NBA prefers binding to HSA than BSA. From the lifetime and rotational relaxation data, it is evident that NBA experiences more restricted environment with HSA compared to BSA with addition of CB7 in the solution. Circular dichroism study indicates that both BSA and HSA, experiences a perturbation in their secondary structures in the presence of NBA and CB7. However, secondary structure of BSA is stabilized whereas, HSA is destabilized in the presence of NBA. From this study, it is evident that there is two types of interaction takes place in these systems. NBA in NBA-BSA-CB7 system undergoes competitive interaction whereas, in NBA-HSA-CB7 system, NBA undergoes cooperative interaction. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study examined the binding interactions of the red emitting molecule NBA with BSA and HSA in the presence of CB7. The results showed a strong preference of NBA for binding with HSA over BSA, and different behaviors of NBA in different environments.