Stimuli-Responsive PAMAM Dendritic Macromolecules for Optical Detection of Food Spoilage

A new category of smart dendritic structure was synthesized by functionalization of poly(amidoamine) (PAMAM) dendrimer with spiropyran molecules to afford photoluminescent dendritic structure (SP-PAMAM). Smart optical sensors were prepared by physical incorporation of oxazolidine molecule (OX) in the SP-PAMAM structure. Investigation of optical properties demonstrated photoinduced electron transfer (PET) between spiropyran end group of SP-PAMAM and oxazolidine molecule. The pH-responsivity of smart macromolecules was used for designing a paper-based pH indicator for visual detection of spoilage in food industry, especially in the case of milk. The prepared papers applied on cap of the milk bottles where a red fluorescence emission was observed after milk spoilage by adsorption of acidic volatile components generated by bacterial degradation and oxidation process on the paper surface.