MicroLED biosensor with colloidal quantum dots and smartphone detection.

A fluorescence sensor with the capability for spatially multiplexed measurements utilizing smartphone detection is presented. Bioconjugated quantum dots are used as the fluorescent tag and are excited using a blue-emitting microLED (µLED). The 1-dimensional GaN µLED array is butt-coupled to one edge of the glass slide to take advantage of total internal reflection fluorescence (TIRF) principles. The bioassays on the top surface of the glass waveguide are excited and the resultant fluorescence is detected with the smartphone. The red, green, and blue channels of the digital image are utilized to spectrally separate the excitation light from the fluorescence for analysis. Using a biotin-functionalized glass slide as proof of principle, we have shown that streptavidin conjugated quantum dots can be detected down to a concentration of 8 nM.

Initial investigations of a novel bioluminescence method for imaging dental demineralization.

OBJECTIVES: In this in vitro study, a bioluminescent marker was investigated for its potential to illuminate the assessment of dental caries and dental erosion, which are significant clinical and public health problems, through its binding of those ions, notably Ca2+ , known to be released during the process of demineralization. MATERIALS AND METHODS: The light output from the selected bioluminescent marker was investigated in several experiments, including: (a)contact with a range of Ca2+ ion concentrations; (b) treatment of extracted teeth with solutions of differing pH, followed by application of the bioluminescence marker to assess Ca2+ ion release; and (c) application of the marker to freshly extracted teeth with natural and artificially created caries lesions on occlusal and smooth surfaces to image the Ca2+ ion distribution. RESULTS: The results of: experiment (a) showed that the light output from the marker increases with increasing Ca2+ concentration and of experiment (b) showed increases in light being observed as increasingly acidic solutions were applied. The results of experiment (c) showed the bioluminescence images of the extracted teeth produced "demineralization maps" of the imaged surfaces. CONCLUSIONS: These results demonstrate the ability of a novel bioluminescence technology to image Ca2+ ions on tooth enamel surfaces which has potential in dental caries and dental erosion applications and provides the scientific basis for the ongoing development of that novel technology.

A wearable phototherapy device utilizing micro-LEDs.

A conformable device for wearable phototherapy applications is presented. The device consists of a 1 mm thick elastomeric membrane edge-lit by specially fabricated micro-sized LEDs. Nanoparticle based scattering films are utilized to extract light and a uniform emission of 15 µW/cm2 is reported over an area of 2 cm2.

Hybrid organic semiconductor lasers for bio-molecular sensing.

Bio-functionalised luminescent organic semiconductors are attractive for biophotonics because they can act as efficient laser materials while simultaneously interacting with molecules. In this paper, we present and discuss a laser biosensor platform that utilises a gain layer made of such an organic semiconductor material. The simple structure of the sensor and its operation principle are described. Nanolayer detection is shown experimentally and analysed theoretically in order to assess the potential and the limits of the biosensor. The advantage conferred by the organic semiconductor is explained, and comparisons to laser sensors using alternative dye-doped materials are made. Specific biomolecular sensing is demonstrated, and routes to functionalisation with nucleic acid probes, and future developments opened up by this achievement, are highlighted. Finally, attractive formats for sensing applications are mentioned, as well as colloidal quantum dots, which in the future could be used in conjunction with organic semiconductors.

An oligofluorene truxene based distributed feedback laser for biosensing applications.

The first example of an all-organic oligofluorene truxene based distributed feedback laser for the detection of a specific protein-small molecule interaction is reported. The protein avidin was detected down to 1 µg mL(-1) using our biotin-labelled biosensor platform. This interaction was both selective and reversible when biotin was replaced with desthiobiotin. Avidin detection was not perturbed by Bovine Serum Albumin up to 50,000 µg mL(-1). Our biosensor offers a new detection platform that is both highly sensitive, modular and potentially re-usable.