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Gold nanoparticles (GNPs) protected by poly(2-ethyl-2-oxazoline) (POZ) of different molecular weights (Mw = 5, 50, 200 and 500 kDa) were synthesised and characterised by dynamic light scattering, nanoparticle tracking analysis, zeta potential measurement and transmission electron microscopy. It was established that the use of POZ with 50 kDa resulted in formation of GNPs with low polydispersity while POZ with greater molecular weights led to formation of more polydisperse GNPs. Fluorescent labelling of these nanoparticles was achieved through their reaction with polyethyleneglycol dithiol (8-12 kDa) as a linker molecule with subsequent reaction with 6-(iodoacetamido) fluorescein. The fluorescent nature of obtained GNPs was confirmed by the appearance of the fluorescence peak at 510 nm that is typical for fluorescein molecules and glowing of the aqueous solution under the UV irradiaton. The fluorescently-labelled GNPs are promising tool in biomedical application to monitor the biological systems using fluorescent microscopy.

A portable device for measuring fluorescence signals from a lateral flow test strip was developed. The aim was to build an easy-to-use, affordable reader device for fast, quantitative analysis of point-of-care tests, made mostly of commercial off-the-shelf components. The device is capable of exciting fluorescent labels with 532 nm and 650 nm lasers and collecting the emitted fluorescent light with a camera. Core of the device is a Raspberry Pi Zero W wireless single board computer that controls the Raspberry Pi camera v2 module and lasers. The computer can also perform the image analysis and communicate the results to a mobile phone application acting as a user interface. Sensitivity of the device was characterized by sweeping the imaging parameters and comparing the performance with a high-grade fluorescence reader. Using dummy LFA samples, it was found that the device is able to detect signals from analyte concentrations that are relevant in biological samples. Image exposure time of $500~\mu \text{s}$ was enough to read a distinguishable signal. The manufacturing costs were estimated to be below 100 euros per device in mass production.

Glucose oxidase (GOx) is an important industrial enzyme that can be optimized for specific applications by mutagenesis and activity.based screening. To increase the efficiency of this approach, we have developed a new ultrahigh.throughput screening platform based on a microfluidic lab.on.chip device that allows the sorting of GOx mutants from a saturation mutagenesis library expressed on the surface of yeast cells. GOx activity was measured by monitoring the fluorescence of water microdroplets dispersed in perfluorinated oil. The signal was generated via a series of coupled enzyme reactions leading to the formation of fluorescein. Using this new method, we were able to enrich the yeast cell population by more than 35.fold for GOx mutants with higher than wild.type activity after two rounds of sorting, almost double the efficiency of our previously described flow cytometry platform. We identified and characterized novel GOx mutants, the most promising of which (M6) contained a combination of six point mutations that increased the catalytic constant kcat by 2.1.fold compared to wild.type GOx and by 1.4.fold compared to a parental GOx variant. The new microfluidic platform for GOx was therefore more sensitive than flow cytometry and supports comprehensive screens of gene libraries containing multiple mutations per gene. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

Highly luminescent nanophosphors (NPs) containing rare earth (RE) ions were successfully prepared by careful control of nanosynthesis. The YVO4:Eu3+ NPs formed core/shell structures with sizes from 10 nm to 25 nm. The NPs were functionalized with biocompatible groups such as OH, NH2 and SCN. A chemical coupling reaction connected the functionalized YVO4:Eu3+ NPs with Biotin via a direct reaction between the functional groups or an intermediate linker. Under UVIS excitation, YVO4:Eu3+ NPs exhibited strong red luminescence with narrow bands corresponding to the intra 4f transitions of D 0 5 – F j 7 (j = 1, 2, 3, 4) Eu3+. The peaks were found at 594 nm ( D 0 5 – F 1 7 ), 619 nm ( D 0 5 – F 2 7 ), 652 nm ( D 0 5 – F 3 7 ) and 702 nm ( D 0 5 – F 4 7 ) with the strongest emission at 619 nm. The fluorescence intensity and stability of the functionalized YVO4:Eu3+ NPs have been increased. This is a promising result in sense of using the conjugates of YVO4:Eu3+ and a bioactive molecule, Biotin for the development of a fluorescent label tool in biomedical analysis.

International audience; Carbon nanotube–chromophore hybrids are promising building blocks in order to obtain a controlled electro-optical transduction effect at the single nano-object level. In this work, a strong spectral selectivity of the electronic and the phononic response of a chromophore-coated single nanotube transistor is observed for which standard photogating cannot account. This paper investigates how light irradiation strongly modifies the coupling between molecules and nanotube within the hybrid by means of combined Raman diffusion and electron transport measurements. Moreover, a nonconventional Raman enhancement effect is observed when light irradiation is on the absorption range of the grafted molecule. Finally, this paper shows how the dynamics of single electron tunneling in the device at low temperature is strongly modified by molecular photoexcitation. Both effects will be discussed in terms of photoinduced excitons coupled to electronic levels.

MicroScale Thermophoresis (MST) is an emerging technology for studying a broad range of biomolecular interactions with high sensitivity. The affinity constant can be obtained for a wide range of molecules within minutes based on reactions in microliters. Here, we describe the application of MST in quantifying two CBM-carbohydrate interactions, a CBM3a toward cellulose nanocrystals and a CBM4 against xylohexaose.

International audience; Preliminary tests in the field of drug storage and release of composite materials known as liposils were described. These silica-based particles were obtained via liposome templating. The non-porous amorphous silica cladding of liposils protected the liposomes which retained the fundamental properties of their phospholipid bilayer. In an improved synthesis, two formulations were used, one with and the other without cholesterol in the phospholipid bilayer. Stability tests were done using carboxyfluorescein as a model hydrophilic drug loaded in the liposomes aqueous phase before the templating process. The stability of the loaded liposils was analyzed at two different pH (1.2 and 7.4) in a flow cell, according to the USP 28 norm. At pH 1.2, the silica shell was stable and prevented their rapid degradation. Interestingly, at pH 7.4 the analysis of the release kinetics revealed that the hydrolysis of the silica shell initially released intact liposomes. Characterizations of liposils were done at various steps of these processes. The stability observed for liposils make them good starting material for drug storage and release schemes. For instance, functionalization of their external surface should improve their capture by cells whereby drug release could then be induced by external stimuli, such as ultrasounds or microwaves.