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.