Polydiacetylene-Based Label Free Sensor with High Sensitivity and Selectivity

Abstract

Polydiacetylenes (PDAs) have been tested as signal transducers for biosensors due to their unique color-changing properties in response to environmental changes such as pH, temperature and molecular binding, As most of the PDA-based sensors reported to date were tested for detecting purified samples, however, their specificity has been rarely evaluated. The molecular mechanism corresponding to the color change is believed to be an irreversible structural transition undergone by the conjugated backbone of the polymer. Such a transition is most likely associated with perturbations to the pendant side chains of the PDA following molecular processes affecting the PDA interface. In this study, novel PDAs that were fabricated on PVDF strips by photoreaction of composite diacetylene self-assemblies were tested for biosensors with minimal nonspecific binding to unwanted-biomolecules. The PDA surface of biotin and ethanolamide bound more specifically to streptavidin than that of biotin only. The optimized PDA biosensor showed more sensitive signal by about 2,850-fold to streptavidin than to bovine serum albumin, a control protein. The findings here suggest that PDAs by employing mixed self-assembly surfaces can be applied for the development of parctical strip biosensors with high sensitivity and specificity for the target detection. To apply the point-of-care testing using PDA-based strip, we investigated a novel strip technology utilizing PDA-conjugate antibody. We conjugated a Microalbuminuria antibody to PDA liposome containing mixed monomer with 60% PCDA and 40% TCDA-OH to reduce the nonspecific binding. The prepared PDA-conjugate antibody was immobilized on the lateral flow strip with nitrocellulose membrane. A blue zone of immobilized PDA-conjugate antibody was changed into red color through antibody-antigen interaction. The PDA-based POCT was available to detect the signal transition without metal-conjugate detector antibody. To enhance our system, furtherm...