Large-scale production and characterization of biocompatible colloidal nanoalumina

Lifetime-Engineered Ruby Nanoparticles (Tau-Rubies) for Multiplexed Imaging of μ-Opioid Receptors

To address the growing demand for simultaneous imaging of multiple biomarkers in highly scattering media such as organotypic cell cultures, we introduce a new type of photoluminescent nanomaterial termed "tau-ruby" composed of ruby nanocrystals (Al₂O₃:Cr³⁺) with tunable emission lifetime. The lifetime tuning range from 2.4 to 3.2 ms was achieved by varying the Cr³⁺ dopant concentration from 0.8% to 0.2%, affording facile implementation of background-free detection. We developed inexpensive scalable production of tau-ruby characterized by bright emission, narrow spectrum (693 ± 2 nm), and virtually unlimited photostability upon excitation with affordable excitation/detection sources, noncytotoxic and insensitive to microenvironmental fluctuations. By functionalizing the surface of tau-rubies with targeting antibodies, we obtained different biomarkers suitable for multiplexed lifetime imaging. As a proof of principle, three tau-ruby bioprobes, characterized by three mean lifetimes, were deployed to label three μ-opioid receptor species expressed on transfected cancer cells, each fused to a unique epitope, so that three types of cells were lifetime-encoded. Robust decoding of photoluminescent signals that report on each cell type was achieved by using a home-built lifetime imaging system and resulted in high-contrast multiplexed lifetime imaging of the cells.

Development of Bright and Biocompatible Nanoruby and Its Application to Background-Free Time-Gated Imaging of G-Protein-Coupled Receptors

At the forefront of developing fluorescent probes for biological imaging applications are enhancements aimed at increasing their brightness, contrast, and photostability, especially toward demanding applications of single-molecule detection. In comparison with existing probes, nanorubies exhibit unlimited photostability and a long emission lifetime (∼4 ms), which enable continuous imaging at single-particle sensitivity in highly scattering and fluorescent biological specimens. However, their wide application as fluorescence probes has so far been hindered by the absence of facile methods for scaled-up high-volume production and molecularly specific targeting. The present work encompasses the large-scale production of colloidally stable nanoruby particles, the demonstration of their biofunctionality and negligible cytotoxicity, as well as the validation of its use for targeted biomolecular imaging. In addition, optical characteristics of nanorubies are found to be comparable or superior to those of state-of-the-art quantum dots. Protocols of reproducible and robust coupling of functional proteins to the nanoruby surface are also presented. As an example, NeutrAvidin-coupled nanoruby show excellent affinity and specificity to μ-opioid receptors in fixed and live cells, allowing wide-field imaging of G-protein coupled receptors with single-particle sensitivity.

Amino organosilane grafted ordered mesoporous alumina with enhanced adsorption performance towards Cr(vi)

Amino organosilane N-(β-aminoethyl)-γ-aminopropylmethylbimethoxysilane (2N) functionalized ordered mesoporous aluminas (MA–2N) with enhanced adsorption performance towards Cr(vi) were successfully prepare by a facile grafting method.

Wide-field time-gated photoluminescence microscopy for fast ultrahigh-sensitivity imaging of photoluminescent probes

Fluorescence microscopy is a fundamental technique for the life sciences, where biocompatible and photostable photoluminescence probes in combination with fast and sensitive imaging systems are continually transforming this field. A wide-field time-gated photoluminescence microscopy system customised for ultrasensitive imaging of unique nanoruby probes with long photoluminescence lifetime is described. The detection sensitivity derived from the long photoluminescence lifetime of the nanoruby makes it possible to discriminate signals from unwanted autofluorescence background and laser backscatter by employing a time-gated image acquisition mode. This mode enabled several-fold improvement of the photoluminescence imaging contrast of discrete nanorubies dispersed on a coverslip. It enabled recovery of the photoluminescence signal emanating from discrete nanorubies when covered by a layer of an organic fluorescent dye, which were otherwise invisible without the use of spectral filtering approaches. Time-gated imaging also facilitated high sensitivity detection of nanorubies in a biological environment of cultured cells. Finally, we monitor the binding kinetics of nanorubies to a functionalised substrate, which exemplified a real-time assay in biological fluids. 3D-pseudo colour images of nanorubies immersed in a highly fluorescent dye solution. Nanoruby photoluminescence is subdued by that of the dye in continuous excitation/imaging (left), however it can be recovered by time-gated imaging (right). At the bottom is schematic diagram of nanoruby assay in a biological fluid.

Enhanced thermal properties in a hybrid graphene–alumina filler for epoxy composites

The inclusion of hybrid LCPBI/RGO and Al₂O₃-APS fillers into a polymer matrix with formation of composites has proven to be an efficient way to improve thermal properties of the composites.