The library-immobilized SELEX comparison: a mimic SELEX method

As a promising recognition molecule, aptamers are widely used in the field of small molecule detection. However, few reports are available on the key factors governing successful aptamer selection. To improve the success rate, the melamine-specific aptamer served as a model to investigate critical factors in library-immobilization-based SELEX methods (GO-SELEX and Beads-SELEX). The results indicated that non-ionic surfactants significantly enhanced the desorption of ssDNA from the graphene oxide (GO) surface in Mode one of the mimic GO-SELEX (GO-facilitated library immobilization and target-induced aptamer release). In contrast, in Mode two of the mimic GO-SELEX, where GO was used solely for non-target-binding aptamer removal, and significant non-specific binding between ssDNA and GO compromised the enrichment efficiency of target-specific sequences, necessitating the use of high target concentrations during SELEX. Similarly, in Beads-SELEX, high target concentrations were required to release specific ssDNA, which also led to a small amount of non-specific ssDNA co-release during the procedures. Other SELEX conditions were also compared and constructive suggestions were provided for facilitating the successful aptamer selection. In summary, this study provided SELEX condition optimization guidance for the selection of aptamers specific to small molecules, when different library-immobilized SELEX methods were performed.