Interestingly, a ∼2.2-fold higher potency for G27-DiMan against DC-SIGN-over DC-SIGNRmediated viral infections also agreed well with their relative MLGI affinity differences measured by fluorescence quenching (i.e., Kd: ~0.20 vs. ~0.54 nM). A comparison of the MLGI affinities measured by fluorescence quenching with viral inhibition data revealed that the Kd and EC50 values do not match directly, possibly due to the different binding environments used in these studies (e.g., solution vs. cell membrane). However, there appeared to have a clear positive correlation between the Kd and EC50 values (i.e., the lower the Kd, the lower the EC50, signifying more potent inhibition). This result suggests that our GNP quenching method developed here could act as a rapid method for estimating relative antiviral potentials for GNP-glycan based entry inhibitors.