I'm having a problem with autofluorescence on a multi-tissue array I'm staining. I'm using an aptamer and I've tried it conjugated with Alexa-Fluor 546 as well as Fluorescein. Both ways have given no good results thus far. These array are FFPE arrays & I have tried several methods to try and fix this problem, such as antigen retrieval and aptamer refolding but none have seemed to work. The negative controls always have higher mean pixel intensity compared to the array stained with aptamer. Does anyone have any suggestions to help decrease autofluorescence?