Colorimetric Logic Gates Based on Poly(2-alkyl-2-oxazoline)Coated Gold Nanoparticles

A straightforward end-capping strategy is applied to synthesize xanthate-functional poly(2-alkyl-2-oxazoline)s (PAOx) that enable gold nanoparticle functionalization by a direct "grafting to" approach with citrate-stabilized gold nanoparticles (AuNPs). Owing to the presence of remaining citrate groups, the obtained PAOx@AuNPs exhibit dual stabilization by repulsive electrostatic and steric interactions giving access to water soluble molecular AND logic gates, wherein environmental temperature and ionic strength constitute the input signals, and the solution color the output signal. The temperature input value could be tuned by variation of the PAOx polymer composition, from 22 degrees C for poly(2-(n)propyl-2-oxazoline)@AuNPs to 85 degrees C for poly(2-ethyl-2-oxazoline)@AuNPs. Besides, advancing the fascinating field of molecular logic gates, the present research offers a facile strategy for the synthesis of PAOx@AuNPs of interest in fields spanning nanotechnology and biomedical sciences. In addition, the functionalization of PAOx with xanthate offers straightforward access to thiol-functional PAOx of high interest in polymer science.