A fluorescent PEBBLE nanosensor for intracellular free zinc

Abstract

The development and characterisation of a fluorescent optical PEBBLE (Probe Encapsulated By Biologically Localised Embedding) nanosensor for the detection of zinc is detailed. A ratiometric sensor has been fabricated that incorporates two fluorescent dyes; one is sensitive to zinc and the other acts as a reference. The sensing components are entrapped within a polymer matrix by a microemulsion polymerisation process that produces spherical sensors that are in the size region of 20 to 200 nm. Cellular measurements are made possible by the small sensor size and the biocompatibility of the matrix. The effects of reversibility, photobleaching and leaching have been examined, as well as the selectivity towards zinc over other cellular ions such as Na+, Ca2+, K+, and Mg2+. The dynamic range of these sensors was found to be 4 to 50 microM Zn2+ with a linear range from 15 to 40 microM. The response time for the PEBBLE is less than 4 s and the sensor is reversible. In addition, the nanosensors are photostable and leaching from the matrix, determined using a novel method, is minimal. These sensors are capable of real-time inter- and intra-cellular imaging and are insensitive to interference from proteins.

Evaluating Nanoparticle Sensor Design for Intracellular pH Measurements

“…Other sensors, such as magnesium, 19 calcium, 43 and zinc 24 sensors, which also rely on the binding of the metabolite the sensor is designed for, could potentially encounter the same problems. pH Measurements in Time and Space.…”

Encapsulation of methylene blue in polyacrylamide nanoparticle platforms protects its photodynamic effectiveness

“…Previous work on both polyacrylamide-based and sol-gel based PEBBLE sensors also demonstrated that the matrix, as expected, prevented macromolecules such as proteins (e.g. bovine serum albumin) from diffusing through [27][28][29]. The matrix protected entrapped dyes from the intracellular environment, thus diminishing interference with the fluorescent properties of the dyes [25].…”

A Conceptual Review of Nanosensors

“…These allow the analyte to permeate the matrix and interact with the indicator dye directly and selectively, thereby causing stimulation or quenching of fluorescence. Direct measurement PEBBLEs have been used for sensing H + [52], Ca 2+ [52], Mg 2+ [59], Zn 2+ [10] and glucose [60]. Sol-gel PEBBLEs are normally designed as dissolved gas sensors, and have been used for sensing dissolved molecular oxygen [57,58].…”