Murphy Brasuel

Nanoscale probes encapsulated by biologically localized embedding (PEBBLEs) for ion sensing and imaging in live cells

This review discusses the development and recent advances of probes encapsulated by biologically localized embedding (PEBBLEs), and in particular the application of PEBBLEs as ion sensors. PEBBLEs allow for minimally intrusive sensing of ions in cellular environments due to their small size (20 to 600nm in diameter) and protect the sensing elements (i.e. fluorescent dyes) by encapsulating them within an inert matrix. The selectivity and sensitivity of these nanosensors are comparable to those of macroscopic ion selective optodes, and electrodes, while the response time and absolute detection limit are significantly better. This paper discusses the principles guiding PEBBLE design including synthesis, characterization, diversification, the advantages and limitations of the sensors, cellular applications and future directions of PEBBLE research.

Subcellular optochemical nanobiosensors: probes encapsulated by biologically localised embedding (PEBBLEs)

Abstract Described here are arguably the worlds smallest stand-alone devices/sensors, consisting of multicomponent nano-spheres with radii as small as 10 nm, occupying ≈1 ppb of a typical mammalian cell’s volume. The probe is prepared from up to seven ingredients and is optimised for selective and reversible analyte detection, as well as sensor stability and reproducibility. Such a sensor probe encapsulated by biologically localised embedding (PEBBLE), is delivered into a cell by a variety of minimally-invasive techniques, including a pico-injector, a gene gun, liposomal incorporation and natural ingestion. These remote nano-optodes (PEBBLEs) have been prepared for pH, calcium, magnesium, potassium and oxygen. The sensor PEBBLEs can be inserted into a cell individually, in clusters (single analyte), in sets (multi-analyte) or in ensembles (single analyte, multiple locations).

Photoexcitation‐Based Nano‐Explorers: Chemical Analysis inside Live Cells and Photodynamic Therapy

PEBBLEs (Probes Encapsulated By Biologically Localized Embedding) are submicron-sized optical sensors designed specifically for minimally invasive analyte monitoring in viable single cells, with applications for real-timeanalysis of drug, toxin, and environmental effects on cell function. PEBBLE nanosensor is a general term that describes a family of matrices and nano-fabrication techniques used to miniaturize many existing optical sensing technologies. The main classes of PEBBLE nanosensors are based on matrices of cross-linked polyacrylamide, cross-linked poly(decyl methacrylate), and sol-gel silica. These matrices have been used to fabricate sensors for H + , Ca 2 + , K + , Na + , Mg 2 + , Zn 2 + , Cu 2 + , Cl, O 2 , NO, and glucose that range from 20 nm to 600 nm in diameter. A number of delivery techniques have been used successfully to deliver PEBBLE nanosensors into mouse oocytes, rat alveolar macrophages, rat C6-glioma, and human neuroblastoma cells. PEBBLEs with several newly emerging directions in design and applications, going from intracellular imaging to in vivo actuating and targeting, are also described. They include photonic, magnetic, and stochastic control and modulation of photo-excitation, and also targeted nano-platforms for photodynamic therapy of brain cancers, as well as contrast enhancement of the MRI for monitoring such therapy.

Ion concentrations in live cells from highly selective ion correlation fluorescent nano-sensors for sodium

Fluorescent spherical nanosensors, or PEBBLEs (probes encapsulated by biologically localized embedding) in the 500 nm -1 /spl mu/m size range have been developed using decyl methacrylate as a matrix. A general scheme for the polymerization and introduction of sensing components creates a matrix that allows for the utilization of the highly selective ionophores used in poly (vinyl chloride) and decyl methacrylate ion-selective electrodes. We have demonstrated that our previously developed scheme can be utilized to tailoring selective submicron sensors for use in intracellular measurements of important analytes for which selective enough fluorescent probes do not exist. The general scheme should work for any available ionophore used in PVC or decyl methacrylate ion selective electrodes, with minor adjustments to account for differences in ionophore charge and analyte binding constant. Sodium nanosensors based on the neutral ionophores monensin decyl ester and sodium ionophore IV have been developed and applied to live C6 glioma cells to demonstrate their utility; the intracellular activity of Na/sup +/-K/sup +/-Cl/sup -/cotransport is followed in real time upon extracellular administration of kainic acid.

Characterization and Applications of Modulated Optical Nanoprobes (MOONs)

Modulated optical nanoprobes (MOONs) are microscopic (spherical and aspherical) particles designed to emit different fluxes of light in a manner that depends on particle orientation. When particle orientation is controlled remotely using magnetic fields (MagMOONs) it allows modulation of fluorescence intensity in any selected pattern including square and sinusoidal waves. The broad range of sizes over which MOONs can be prepared allows them to be tailored to applications from intracellular sensors using submicron MOONs to immunoassays using larger MOONs (1-10µm). In the absence of external fields, or material that responds to external fields, the particles tumble erratically due to Brownian thermal forces. These erratic changes in orientation cause the MOONs to blink. The temporal pattern of blinking contains information about the local rheological environment and any forces and torques acting on the MOONs.

Pebble Nanosensors for Real Time Intracellular Chemical Imaging

Publisher Summary This chapter discusses the probes encapsulated by biologically localized embedding (PEBBLE) nanosensors and their application in real-time intracellular imaging. PEBBLE nanosensors are submicron-sized optical sensors designed specifically for minimally invasive analyte monitoring in viable single cells with applications for real-time analysis of drug, toxin, and environmental effects on cell function. PEBBLE nanosensor is a general term that describes a family of matrices and nano-fabrication techniques used to miniaturize many existing optical sensing technologies. The main classes of PEBBLE nano-sensors are based on matrices of cross-linked polyacrylamide, cross-linked decyl methacrylate, and sol-gel silica. These matrices have been used to fabricate sensors for H + Ca 2+ , K + , Na + , Mg 2+ , Zn 2+ , Cl - , NO 2 , O 2 , NO, and glucose that range from 20 nm to 600 nm in size. A host of delivery techniques have been used successfully to deliver PEBBLE nanosensors into mouse oocytes, rat alveolar macrophages, rat C6-glioma, and human neuroblastoma cells.

Fluorescent Pebble Nano-Sensors and Nanoexplorers for Real-Time Intracellular and Biomedical Applications

PEBBLEs (Probes Encapsulated By Biologically Localized Embedding) are sub-micron sized optical sensors specifically designed for minimally invasive analyte monitoring in viable, single cells with applications for real time analysis of drug, toxin, and environmental effects on cell function. PEBBLE nanosensor is a general term that describes a family of matrices and nano-fabrication techniques used to miniaturize many existing optical sensing technologies. The main classes of PEBBLE nanosensors are based on matrices of cross-linked polyacrylamide, cross-linked poly(decyl methacrylate), and sol-gel silica. These matrices have been used to fabricate sensors for H+, Ca2+, K+, Na+, Mg2+, Zn2+, Cu2+, Cl−, O2, NO, and glucose that range from 20 nm to 600 nm in diameter. A number of delivery techniques have been used successfully to deliver PEBBLE nanosensors into mouse oocytes, rat alveolar macrophages, rat C6-glioma, and human neuroblastoma cells. For majority of this chapter, we will focus on the fabrication, characterization and applications of all the different kinds of PEBBLE sensors developed up to date. In the remainder of the chapter, we will introduce a new family of PEBBLEs with several emerging directions in PEBBLE design and applications, from intracellular imaging to in-vivo actuating and targeting.