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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 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.

Work toward the utilisation of an organic laser as a bacterial growth detector is presented here. The sensor used is an optically excited 2nd order DFB (distributed feedback laser) made of oligofluorene truxene. In the drive towards a practical bacterial growth detector, temperature stability and the optimum growth conditions of bacteria are challenges to be overcome. The resultant DFB laser exhibits a sensitivity of 9 nm/RIU.

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.

A micro-LED-coupled multimode slab waveguide is reported for fluorescence sensing. The device consists of a 1-dimensional micro-LED array coupled to a sub-mm polymeric slab for evanescent excitation of fluorescent analytes present on the surface. Proof-principle detection of semiconductor nanocrystals down to 0.2 pM/cm2 is demonstrated.

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.

The sensing capabilities of an all-organic semiconductor distributed feedback laser based on star-shaped truxene-core molecules are described. Two assays are presented as a proof-of-principle demonstration. In the first, concentration changes in the range of 5–60% (v/v) glycerol solution in water were measured with a bulk detection sensitivity of 21 nm per refractive index unit. Secondly, layer-by-layer adsorption of polyelectrolytes to the laser surface, up to a thickness of ≈45 nm, was measured. The experimental results from both assays are compared to, and shown to agree with, a theoretical model. Organic semiconductor lasers of this type have a number of attractions including ease of large-scale fabrication, incorporation into existing assay equipment and no rigid optical alignment constraints for excitation and collection of emission, which makes them well-suited to sensing applications. Therefore, it is expected that this technology will be useful in biosensing applications where label-free samples are investigated.

Organic distributed feedback lasers can detect nanoscale materials, and are, therefore, an attractive sensing platform for biological and medical applications. In this paper, we present a model for optimizing such laser sensors, and discuss the advantages of using an organic semiconductor as the laser material in comparison to dyes in a matrix. The structure of the sensor and its operation principle are described. Bulk and surface sensing experimental data using oligofluorene truxene macromolecules and a conjugated polymer for the gain region are shown to correspond to modeled values and is used to assess the biosensing attributes of the sensor. A comparison between organic semiconductor and dye-doped laser sensitivity is made and analyzed theoretically. Finally, experimental and theoretical specific biosensing data are provided, and methods for improving sensitivity are discussed.

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 View the MathML source1μgmL−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 View the MathML source50,000μgmL−1. Our biosensor offers a new detection platform that is both highly sensitive, modular and potentially re-usable.

The help of Dr. P. Edwards from the Physics Department of the University of Strathclyde for scanning electron microscopy is gratefully acknowledged. This work was supported under the EPSRC projects EP/J021962/1, EP/I029141/1 and EP/K004670/1. HVD, HDS, EM and YG also gratefully acknowledge support from Singapore National Research Foundation under the project NRF-CRP-6-2010-02 and NRF-RF-2009-09. HVD also wishes to acknowledge ESF-EURYI and WBA-Turkish National Academy of Sciences Low-threshold, gain switched colloidal quantum dot (CQD) distributed-feedback lasers operating in the nanosecond regime are reported and proposed for sensing applications for the first time to the authors' knowledge. The lasers are based on a mechanically-flexible polymeric, second order grating structure overcoated with a thin-film of CQD/PMMA composite. The threshold fluence of the resulting lasers is as low as 0.5 mJ/cm(2) for a 610 nm emission and the typical linewidth is below 0.3 nm. The emission wavelength of the lasers can be set at the design stage and laser operation between 605 nm and 616 nm, while using the exact same CQD gain material, is shown. In addition, the potential of such CQD lasers for refractive index sensing in solution is demonstrated by immersion in water. (C) 2014 Optical Society of America Engineering & Physical Sciences Research Council (EPSRC) EP/J021962/1 EP/I029141/1 EP/K004670/1 Singapore National Research Foundation NRF-CRP-6-2010-02 NRF-RF-2009-09 Engineering & Physical Sciences Research Council (EPSRC) EP/K004670/1 EP/I029141/1 EP/J021962/1