I am using Thermo maxisorp 96 well immuno plates (https://www.thermofisher.com/order/catalog/product/437111) to attach whole virus particle. and then after incubation with FAM labelled aptamers, I measured the aptamer binding efficiency towards the virus. When I coat the plates with only coating buffer (50mM carbonate buffer, pH 9.2) I observe the high background binding only with aptamers, there was no virus in the plates. What can be the reason for the high background binding and how I can get rid of this?

Thanks