1-Ethyl-3-methylimidazolium ethylsulfate/copper catalyst for the enhancement of glucose chemiluminescent detection: effects on light emission and enzyme activity.

The effect of the ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate ([Emim][EtSO(4)]) on the copper-catalyzed luminol chemiluminescence (CL) is reported. A drastic light emission enhancement is observed, related to a strong interaction between Cu(2+) and the imidazolium ring. In these conditions, the CL reaction was able to produce light efficiently at pH as low as 6.5 (amplification factor: Intensity(+IL)/Intensity(-IL) = 2900). Interesting effects of [Emim][EtSO(4)] on the enzyme glucose oxidase activity were also evidenced, and advantages were taken from this enhancement to perform sensitive chemiluminescent glucose detection (LOD = 4 microM) at pH 8.0.

Chelating Langmuir-Blodgett film: a new versatile chemiluminescent sensing layer for biosensor applications.

The present study reports the achievement of a new chemiluminescent sensing layer able to simultaneously (i) play an active role on ligand immobilization and (ii) serve as a catalyst in detection processes for label-free biosensor applications. This new type of active Langmuir-Blodgett (LB) monolayer has been designed by using a chelating lipid (Ni-NTA-DOGS). Thanks to the chelated metallic cation, this peculiar lipid exhibits luminol chemiluminescence catalysis properties in the presence of hydrogen peroxide. Upon biomolecule interaction through imidazole ring chelation (mediated by the metallic cation bound to the lipid headgroup), the chemiluminescent signal can be modulated. The first chemiluminescent signal acquisition experiments have shown a strong and homogeneous signal of the chelating layer. Upon histamine interactions, a histidine derivative used as a marker of fresh food quality, we succeeded in obtaining as a proof of concept a chemiluminescent signal variation without any derivatization of the target molecule. This signal variation was shown to be directly correlated to the histamine concentration with a limit of detection of 2 microg/mL.