Supramolecular Chemistry Applied to nanosensor design based on metal enhanced fluorescence

BRACAMONTE A.G., BROUARD D., MAGNAN F., L.-VIGER M., AND BOUDREAU D.

Montreal

Congreso; CSC, Canadian society for chemistry 2011; 2011

Metal-enhanced fluorescence (MEF) is a well known effect that can be applied to nanoparticle-based biosensing. Moreover, the functionalization of the nanoparticle's surface is one method for tuning their overall properties to fit targeted applications. In this work, we are developing a class of plasmon-enhanced nanosensors based on the specific supramolecular interactions of ß-cyclodextrin (ßCD) with selected organic molecules. Cyclodextrins are cyclic oligosaccharides consisting of six (aCD), seven (ßCD) or eight (cCD) units of aD-glucose linked by a-(1,4) bonds. These macrocycles have a nanocavity which allows them to act as hosts to form inclusion complexes with guest molecules. To evaluate this design strategy, we used as a substrate Rhodamine B (RhB), which has a strong association constant with ßCD (5700 M-1). We grafted the ßCD onto gold nanoparticles using linkers of different lengths. Steady-state spectrofluorescence measurements showed an increase in RhB signal by as much as 56 %, for a calculated ßCD concentration not exceeding ~ 0.5 nM over the total nanoparticle surface. Moreover, timeresolved luminescence measurements showed a significant decrease in the averages values (tav) of RhB in the presence of the nanosensor (tav = 1.05 ns) with respect to that of free RhB molecules in phosphate buffer (t =1.7 ns) and in presence of free gold nanoparticles (tav=1.6 ns) was measured. These results and their implication for analytical determinations.aCD), seven (ßCD) or eight (cCD) units of aD-glucose linked by a-(1,4) bonds. These macrocycles have a nanocavity which allows them to act as hosts to form inclusion complexes with guest molecules. To evaluate this design strategy, we used as a substrate Rhodamine B (RhB), which has a strong association constant with ßCD (5700 M-1). We grafted the ßCD onto gold nanoparticles using linkers of different lengths. Steady-state spectrofluorescence measurements showed an increase in RhB signal by as much as 56 %, for a calculated ßCD concentration not exceeding ~ 0.5 nM over the total nanoparticle surface. Moreover, timeresolved luminescence measurements showed a significant decrease in the averages values (tav) of RhB in the presence of the nanosensor (tav = 1.05 ns) with respect to that of free RhB molecules in phosphate buffer (t =1.7 ns) and in presence of free gold nanoparticles (tav=1.6 ns) was measured. These results and their implication for analytical determinations.-1). We grafted the ßCD onto gold nanoparticles using linkers of different lengths. Steady-state spectrofluorescence measurements showed an increase in RhB signal by as much as 56 %, for a calculated ßCD concentration not exceeding ~ 0.5 nM over the total nanoparticle surface. Moreover, timeresolved luminescence measurements showed a significant decrease in the averages values (tav) of RhB in the presence of the nanosensor (tav = 1.05 ns) with respect to that of free RhB molecules in phosphate buffer (t =1.7 ns) and in presence of free gold nanoparticles (tav=1.6 ns) was measured. These results and their implication for analytical determinations.tav) of RhB in the presence of the nanosensor (tav = 1.05 ns) with respect to that of free RhB molecules in phosphate buffer (t =1.7 ns) and in presence of free gold nanoparticles (tav=1.6 ns) was measured. These results and their implication for analytical determinations.tav = 1.05 ns) with respect to that of free RhB molecules in phosphate buffer (t =1.7 ns) and in presence of free gold nanoparticles (tav=1.6 ns) was measured. These results and their implication for analytical determinations.tav=1.6 ns) was measured. These results and their implication for analytical determinations.