Binding interactions of cationic gemini surfactants with gold nanoparticles-conjugated bovine serum albumin: A FRET/NSET, spectroscopic, and docking study

Refolding of denatured gold nanoparticles-conjugated bovine serum albumin through formation of catanions between gemini surfactant and sodium dodecyl sulphate

“…Refolding of the unfolded conjugated AuNPs-BSA has been carried out at a concentration of 0.2 mM each of gemini surfactant, 12-4-12,2Br − and 12-8-12,2Br − based on our previous reports. 13 Fig. S1 † shows the binding isotherm to display binding between the conjugated AuNPs-BSA and gemini surfactants based on changes in fluorescence intensity and α-helix% with an increase in surfactant concentration.…”

“…Zetasizer Nano-ZS 90 from Malvern Instruments Ltd was used for DLS measurements. 13 The Milli-Q water was first filtered with 0.22 μm pore size filter paper (Millipore) and that was used to prepare the buffer solution. This buffer solution filtered with the same filter paper was then used to prepare BSA, gemini surfactant and SDS solutions.…”

“…The sample preparation for FT-IR measurements, its parameters and instrumental details have been reported earlier. 13 Each measurement was recorded three times and the corresponding standard deviations obtained are given in the relevant figures and tables accordingly. The temperature was kept fixed at 298.15 ± 1 K for all measurements.…”

“…Earlier, the unfolding of the conjugated AuNPs-BSA has been carried out by these two cationic gemini surfactants and demonstrated by the FRET/NSET method. 13 After the consolidation of the gemini surfactant-BSA binding isotherm, the refolding study of unfolded bioconjugated protein using SDS through the formation of catanion/mixed assemblies with gemini surfactant has been performed by the FRET and NSET methods. On interacting with cationic gemini surfactant molecules, SDS molecules form catanion due to the oppositely charged headgroups.…”

“…It is well established in our previous report that the protein's helicity is majorly retained even after bioconjugation in its native as well as unfolded states. 13 The ionic surfactants have a strong affinity to bind to the proteins stepwise. Thus, a detailed picture of the protein–surfactant interactions is presented here.…”