OPTICAL NANOSENSORSSensors with at least one of its dimension in nanoscale
Designed for making quantitative measurements in the intracellular environment.
PEBBLE Probe Encapsulated By Biologically
Localized Embedding. PEBBLEs are nano-scale sensing devices
which encapsulate an analyte-specific dye and a reference dye inside a biologically inert matrix
These have been developed for several analyte, including calcium, potassium.etc..
CLASSIFICATIONPEBBLEs : four types - matrices
four types - PEBBLE delivery into the cell. Two types - based of their working principles
The four types of PEBBLE matrices commonly used are: * Polyacrylamide(PAA) * Sol-gel * Polydecylmethacrylate (PDMA) * Organically modified silicates
DELIVERY SYSTEMSLiposomal delivery
Gene gun
Picoinjection
Phagocytosis
WORKING PRINCIPLE(a) direct measurement PEBBLEs and (b) ion correlation PEBBLEs.
a).....* Sense ions and small molecules* used for sensing H+, Ca2+,
Mg2+,Zn2+ and glucose.* some analyte lack highly selective
fluorescent indicators.
b)....consists of a silent ionophores and a
chromoionophore bound togetherSilent-high affinity towards the ion of
interestChromo-fluorescent behaviourDue to a change in pH of the
chromophore as a result of the change in the H+ concentration, the fluorescent behaviour of the chromophore is expressed
ION CO-RELATION
ADVANTAGESPEBBLE :protects the cell from the dye
protects indicator dyes from cellular interference
multiple dyes, ionophores, and other components can be combined to create complex sensing schemes
Minimal physical perturbation of the cell
Small sensor size enables rapid measurement
Applications Diagnosis and monitoring of diseases.
Study early-embryo development
Useful for quantitative measurements in intracellular environment.
Measure Zinc production and localization in brain tissue.
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