Fluorescence enhancement of photosynthetic complexes separated from nanoparticles by a reduced graphene oxide layer

We observe that introducing a layer of reduced graphene oxide between electrochemically deposited gold nanoparticles and natural photosynthetic Fenna–Matthews–Olson (FMO) complex from green sulfur bacteria, results in an increase of the fluorescence emission of the FMO. This increase is not accompanied with any substantial change of the fluorescence dynamics. Our findings indicate that incorporating graphene-based materials in hybrid assemblies yields better performance of such structures, thus holds promise for designing biosensing and optoelectronic devices

Fingermark detection using upconverting nanoparticles and comparison with cyanoacrylate fuming.

This paper reports the synthesis of high-quality upconverting nanoparticles (UCNPs) - sodium yttrium tetrafluoride doped with ytterbium and erbium (NaYF4:Yb,Er) with a silica shell and capped with phenyl functional groups. The main goal of this research was to design tailor-made UCNPs for fingermark detection, to test and validate a nanoparticle-based detection technique and to compare their performance against a benchmark method to assess potential implementation in routine practice by law enforcement agencies. The water-based UCNPs solution was applied to natural fingermarks on a number of substrates. This is the first ever systematic comparative study between UCNPs and a benchmark fingermark detection technique - cyanoacrylate fuming (CAF) followed by luminescent dye staining. Fingermark detection effectiveness was studied by treating 300 latent fingermark specimens on aluminium foil, polyethylene, polypropylene and glass slides. It was concluded that, on average, CAF performed better across the substrates tested. Nevertheless, UCNPs can be advantageous for fingermark detection on multicoloured, patterned or luminescent substrates due to their unique optical properties. There are, however, shortfalls associated with their synthesis and use that need to be addressed before they can be considered for operational purposes

Immunosensor Based on Long-Period Fiber Gratings for Detection of Viruses Causing Gastroenteritis

Since the norovirus is the main cause of acute gastroenteritis all over the world, its fast detection is crucial in medical diagnostics. In this work, a rapid, sensitive, and selective optical fiber biosensor for the detection of norovirus virus-like particles (VLPs) is reported. The sensor is based on highly sensitive long-period fiber gratings (LPFGs) coated with antibodies against the main coat protein of the norovirus. Several modification methods were verified to obtain reliable immobilization of protein receptors on the LPFG surface. We were able to detect 1 ng/mL norovirus VLPs in a 40-min assay in a label-free manner. Thanks to the application of an optical fiber as the sensor, there is a possibility to increase the user’s safety by separating the measurement point from the signal processing setup. Moreover, our sensor is small and light, and the proposed assay is straightforward. The designed LPFG-based biosensor could be applied in both fast norovirus detection and in vaccine testing

Molecular monolayers on silicon as substrates for biosensors

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