Recent Developments in Micelle-Induced Fluorescent Sensors

Encapsulation of lipophilic active species inside hydrophobic core of surfactant micelles or binding of ionic active species at the oppositely charged micellar surface display great potential to alter the communication between two active species (e.g., fluorophore, quencher and receptor molecule etc.) in pure aqueous systems. This encapsulation of the active components inside the micellar nano-cage has been exploited, by us and other research groups, to design new classes of fluorescent chemosensors or to enhance the sensitivity and selectivity of the existing sensor systems. Surfactant molecules can also form supramolecular aggregates with macromolecules (e.g., polymer), via various supramolecular interactions like hydrogen bonding, hydrophobic or electrostatic interaction. The encapsulation of the active species in the nano-cage of this self-assembled system provides close proximity between themselves. This proximity can be controlled by the formation and deformation of this aggregate by changing simple solution parameters (e.g., pH) or by binding with specific bioanalytes (e.g., protein). In this paper we have reviewed recent trends (2008 onwards) of micelle-induced fluorescent chemosensors, with a few examples of micelle-induced sensory activity enhancement, analyte (e.g., metal ions or bio-analyte like protein) specific sensor systems, and tuning of the sensing property of a sensor system within a pH window.