Chemical sensing/sensors Chemosensors

Although the construction of sensors for external physical stimuli, such as light, heat or pressure, is relatively simple, it becomes more complicated when the target stimuli come from atoms or molecules. These types of sensors are often referred to as chemical sensors or chemosensors and biochemical sensors or biosensors (see below in Sects. 1.2 and 1.3). For the latter types, a sensing material should be used that can respond to the presence of the target analyte. This response may or may not be obviously true with vague information. Hence, chemo- and biosensors should be... 

PEBBLEs are water-soluble nanoparticles based on biologically inert matrices of cross-linked polymers, typically poly(acrylamide), poly(decylmethacrylate), silica, or organically modified silicates (ORMOSILs), which encapsulate a fluorescent chemo-sensor and, often, a reference dye. These matrices have been used to make sensors for pH, metal ions, as well as for some nonionic species. The small size of the PEBBLE sensors (from 20 to 600 nm) enables their noninvasive insertion into a living cell, minimizing physical interference. The semipermeable and transparent nature of the matrix allows the analyte to interact with the indicator dye that reports the interaction via a change in the emitted fluorescence. Moreover, when compared to naked chemosensors, nanoparticles can protect the indicator from chemical interferences and minimize its toxicity. Another important feature of PEBBLEs, particularly valuable in intracellular sensing applications, is that the polymer matrix creates a separate... 

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