Particle sensors based on amplified quenching of conjugated polymers for biosensing applications

Abstract

Conjugated polymers (CP)s display unique material properties that allow for implementation as sensors. For sensors to operate in complex biological environments, it is important to address the issues of sensitivity and specificity. To develop these attributes in a biosensor design, CPbased core-shell particles have been investigated as potential material platforms to detect protease activity. CP-based particles have greater sensitivity versus CPs in solution due to interchain and intrachain interactions afforded in the solid state. The CP core of the particle can be made using layer-by-layer assembly, a versatile technique that forms uniform polymeric films through non-covalent interactions. To measure the response of CP core particles in aqueous environments, a quantitative ratiometric approach was developed to account for system fluctuations encountered with particle dispersions. This method can help assess the molecular design of polymers and quenchers in a systematic approach. CP core particles, because of their electrostatic charge, suffer from nonspecific interactions with other charged species, and thus encapsulating CP particles with a hydrogel shell should create sensor materials with higher specificity.

(cont.) To illustrate this concept, CP-particle containing hydrogel films were created to permit selective interactions with designed quenchers. The encapsulation of the individual CPcore particles was accomplished through atom transfer radical polymerization (ATRP) of functional monomers from the surface, and the choice of reactive group on the monomer allows for bioconjugation on the particle shell. Future core-shell materials can also be developed with ATRP, and give prospects to new schemes for CP-based biosensing.