Evolutionary Screening of High-Affinity DNA Functional Ligands for the IgG Fc Segment Based on MLR Models and Their Application in Toxin Detection

Abstract This paper is based on a series of DNA functional ligands (DNAFLs) capable of recognizing the Fc segment of antibodies, which were previously obtained by our research group. The structural features of these ligands were characterized using molecular descriptors, and principal component analysis (PCA) was performed on their structural features. A multiple linear regression model (MLR) was then established to quantitatively describe the relationship between DNAFLs and the Fc segment. Guided by the structure of a template, the ligand sequences were truncated to optimize their architectures, key binding sites were identified, and random mutations were introduced at specific positions to construct a candidate DNAFL library. The affinities of the ligands in the library were predicted using the model and subsequently validated experimentally, ultimately yielding a high-affinity DNAFL (HA-DNAFL) with an approximately 5-fold improvement in binding affinity. Furthermore, this study achieved oriented immobilization of antibodies onto the BLI sensing interface using the evolved HA-DNAFL and constructed an immunosensor for the detection of abrin. The limit of detection was 4-fold and 16-fold lower than those obtained using conventional oriented and non-oriented immobilization methods, respectively, demonstrating superior detection performance. Collectively, the HA-DNAFL obtained through evolutionary screening in this work not only serves as a novel material for oriented antibody immobilization but also holds significant promise for the development and application of advanced, high-performance immunosensors.