Systematic optimization of aptamer self-assembly on graphene transistor gates for rapid detection of chloramphenicol residues in milk

Chloramphenicol (CAP) residues in milk pose severe health risks, yet current detection methods (e.g., chromatography-mass spectrometry) suffer from complexity and high costs. In this work, we address this gap by developing an ultrasensitive aptamer-gated graphene Field-effect biosensor. A self-assembled Aptamer-functionalized solution-gated graphene transistor (Apt-SGGT) was engineered via systematic optimization of aptamer surface density to overcome spatial-confinement limitations and enhance conformational switching efficiency. We applied the Apt-SGGT biosensor to the analytical determination of CAP in actual skim milk samples, achieving a detection limit as low as 21.5 pM with a spiked recovery rate of 97.65 % ± 5.72 %. This study not only presents a promising platform for the rapid, on-site detection of antibiotic residues in complex food matrices but also provides a generalizable interfacial engineering strategy to enhance the performance of aptamer-based field-effect biosensors.