pH-responsive photoluminescent LbL hydrogels with confined quantum dots

We report on responsive photoluminescent hybrid materials with quantum dots immobilized in organized manner fabricated by spin-assisted layer-by-layer assembly (SA LbL). The strongly interacting polyelectrolytes such as poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS) serve for confining CdTe nanoparticles stabilized by thioglycolic acid, while a poly(methacrylic acid) (PMAA) hydrogel matrix presents an elastomeric network with pH-responsive properties. Quantum dot layers encapsulated in PSS-PAH bilayers are confined inside this hybrid hydrogel matrix. The system undergoes reversible changes in photoluminescent intensity in response to pH variations. Photoluminescent intensity of the hybrid matrix is suppressed in excess negative charge at high pH, but excess positive charge at low pH results in significant photoluminescence increase. Such hybrid quantum dot-containing hydrogel-LbL assemblies provide a way for a novel design of materials with precisely controlled structure and pH-triggered optical properties which might be developed into or pH- or chemical sensors.

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