development of molecular logic gates mimics (MLGMs), being first proposed using PET based fluorescent chemosensors by de Silva and co-workers in 1993. Molecules have been made to operate in accordance with Boolean algebra that performs a logical operation based on one or more physical or chemical inputs. The field has advanced from the development of simple logic systems based on a single chemical input to molecules capable of carrying out complex and sequential operations. Applications of Chemosensors Chemosensors have been incorporated through surface functionalization onto particles and beads such as metal based nanoparticles, quantum dots, carbon-based particles and into soft materials such as polymers to facilitate their various applications. Other receptors are sensitive not to a specific molecule but to a molecular compound class, these chemosensors are used in array- (or microarray) based sensors. Array-based sensors utilise analyte binding by the differential receptors. One example is the grouped analysis of several tannic acids that accumulate in ageing Scotch whisky in oak barrels. The grouped results demonstrated a correlation with the age but the individual components did not. A similar receptor can be used to analyze tartrates in wine. The application of chemosensors in cellular imaging is particularly promising as most biological process are now monitored by using imaging technologies such as confocal fluorescence and superresolution microscopy, among others. The compound saxitoxin is a neurotoxin found in shellfish and a chemical weapon. An experimental sensor for this compound is again based on PET. Interaction of saxitoxin with the sensor's crown ether moiety kills its PET process towards the fluorophore and fluorescence is switched from off to on. The unusual boron moiety makes sure the fluorescence takes place in the visible light part of the electromagnetic spectrum. See also Boronic acids in supramolecular chemistry: Saccharide recognition Host–guest chemistry Molecular machine Molecular recognition References Supramolecular chemistry Molecular machines