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. Author manuscript; available in PMC: 2021 Sep 12.
Published in final edited form as: J Phys Chem B. 2020 Apr 30;124(19):3892–3902. doi: 10.1021/acs.jpcb.0c01444

Figure 6.

Figure 6.

Affinity pull-down experiment probing the binding of strep-tagged AuGSHzwt to Streptactin-coated sepharose beads. (a) Schematic illustration of the pull-down assay (drawing not to scale). Strep-tagged AuGSHzwt particles are dispersed in different biological media (including PBS, DMEM medium, 40 mg/mL BSA and undiluted FBS) and left to incubate for 24 h; a shorter incubation time of 1 h in FBS is also performed for comparison. Next, Streptactin-coated beads are introduced into solution and left to incubate for an extra 30 min under mild agitation. After settling of the beads, the presence of AuNPs in the supernatant is verified by recording absorbance values at 500 nm. Preferential binding of strep-tagged AuNPs to Streptactin over the serum proteins leaves a clear supernatant phase (low absorbance readings at 500 nm) in the pull-down assay. (b,c) Analysis of pull-down experiments probing (b) AuGSHzwt@1st and (c) AuGSHzwt@10st binding to Streptactin-coated beads. Columns labeled ‘no beads’ give absorbance readings of strep-tagged AuNPs in PBS solution in the absence of beads.