Electrochemiluminescence in Thermo-Responsive Hydrogel Films with Tunable Thickness

Electrochemiluminescence(ECL)has attracted considerable interest for many applications such as microscopy,(bio)analysis,light-emitting materials or devices.In this work,we report the fabrication and characterization of ECL-active hydrogel films with tunable thickness.The redox films were prepared by electrochemically-assisted radical polymerization by potential cycling of a PBS solution containing the monomer N-isopropylacrylamide,the initiator potassium persulfate,the cross-linker N,N′-methylenebis(acrylamide)and the Ru(bpy)3 monomer.The deposits were easily prepared in a rapid and well-controlled one-step procedure.The resulting homogeneous films are composed of a poly(N-isopropylacrylamide)(pNIPAM)matrix,which incorporates covalently[Ru(bpy)_(3)]^(2+)centers.The thickness and the number of ECL-active sites is tuned by control-ling the number of voltammetric scans.The deposited pNIPAM films are permeable to water-soluble chemicals such as the coreactant tri-n-propylamine(TPrA).The voltammetric characterization shows a continuous increase of the number of redox-active sites.Results indicate that ECL signals are proportional to the number of electrodeposited[Ru(bpy)_(3)]^(2+)centers.Such approach combining ECL and stimuli-responsive hydrogels open exciting prospects for developing new(bio)sensing materials.