Probing aptamer-mucin 1 binding events on polydopamine@carbon nanotubes modified cellulose paper interface using speckle pattern analysis for label free aptasensing

Herein, we have developed a cellulose paper-based aptasensing protocol by employing dynamic laser speckle (DLS) analysis for direct and label-free probing of the binding interface. Cellulose filter paper surface was modified by using the mussel adhesion chemistry of polydopamine modified carbon nanotubes (PDA@CNTS). The mussel chemistry resulted in strong adhesion and binding of PDA@CNTs on cellulose paper surface. The modified surface was subsequently employed in the construction of label free aptasensor for detection of cancer biomarker mucin 1 (MUC1). Taking advantage of DLS technique, it provided us with sensitive and accurate analysis of target biomarker MUC1 by the intrinsic randomness of patterns generated from cellulose based paper surface. The developed aptasensor was evaluated using DLS at various fabrication steps, where the scattered laser beams from these samples were collected and analyzed based on the obtained speckle patterns. Under the optimal experimental conditions, paper-based aptasensor achieved sensitive and selective detection of MUC1, exhibiting excellent linear range (15–100) µM with a limit of detection of 1 µM. This work presents a novel study of promising laser speckle paper-based aptasensor, providing new insights for the development of low-cost, sensitive, and portable paper-based analytical tools for biological applications.