Arnaud Brioude

Direct detection of rare nucleic-acid targets without molecular amplification requires specific recognition events to be made observable while remaining distinguishable from nonspecific interactions. Here, we introduce a microbead-based heterodimer assay (MBHA) that converts two-site recognition of single-stranded DNA into spatially resolved, two-color bead-pairing events for direct nucleic-acid detection. Two spectrally distinct microbead populations are functionalized with partially double-stranded DNA probes exposing target-binding domains complementary to separate regions of the target. Target-mediated bridging produces heterotypic bead pairs that are classified by fluorescence identity and an interparticle-distance criterion, while residual background is evaluated relative to blank measurements. Under the tested conditions, 166 fM was the lowest target concentration exceeding the blank-derived detection threshold. A sequence-scrambled synthetic non-target DNA remained below threshold across the tested concentration range, and detection at 166 fM was retained in the presence of 1 µM non-target DNA, corresponding to an approximately six-million-fold molar excess. Probe redesign further extended the assay to a second 60-nucleotide synthetic DNA target derived from the SARS-CoV-2 ORF1ab sequence. This proof-of-concept study establishes heterodimer counting as an amplification-free measurement strategy in which rare molecular-recognition events are made directly observable and individually classifiable without increasing target copy number.

Electrochemical behavior of silver nanoparticles in mesoporous oxides electrodes is investigated. Mesoporous SiO₂ and TiO₂ films deposited on FTO (fluorine-doped tin oxide) and containing Ag nanoparticles (NPs) are used as electrodes. The study of voltammetric curves (CVs) and the diffusion of Ag⁺ ions out of the films highlight the importance of the retention of Ag⁺ ions by the TiO₂ films. By varying several factors such as the speed rate or the initial potential, we observe the existence of the two potentials' anodic peaks. These are explained by the nature of two silver NP populations created in two distinct areas in the film and with different size distributions, as shown by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. The size distributions of the two NP populations allow the position and shape of each of the oxidation peaks in the CVs to be adequately simulated.

Multiphasic scaffolds that combine different architectural, physical, and biological properties are the best option for the regeneration of complex tissues such as the periodontium. Current developed scaffolds generally lack architectural accuracy and rely on multistep manufacturing, which is difficult to implement for clinical applications. In this context, direct-writing electrospinning (DWE) represents a promising and rapid technique for developing thin 3D scaffolds with controlled architecture. The current study aimed to elaborate a biphasic scaffold using DWE based on two polycaprolactone solutions with interesting properties for bone and cement regeneration. One of the two scaffold parts contained hydroxyapatite nanoparticles (HAP) and the other contained the cementum protein 1 (CEMP1). After morphological characterizations, the elaborated scaffolds were assessed regarding periodontal ligament (PDL) cells in terms of cell proliferation, colonization, and mineralization ability. The results demonstrated that both HAP- and CEMP1-functionalized scaffolds were colonized by PDL cells and enhanced mineralization ability compared to unfunctionalized scaffolds, as revealed by alizarin red staining and OPN protein fluorescent expression. Taken together, the current data highlighted the potential of functional and organized scaffolds to stimulate bone and cementum regeneration. Moreover, DWE could be used to develop smart scaffolds with the ability to spatially control cellular orientation with suitable cellular activity at the micrometer scale, thereby enhancing periodontal and other complex tissue regeneration.

The luminescent complex [(ThiaSO₂)₂(Mn^II)₄F]⁻ (ThiaSO₂ = p-tert-butylsulfonylcalixarene) was introduced between layered double hydroxides. The material displays a very high sensitivity to its luminescence emission with oxygen.

Along with the development of hydrogen as a sustainable energy carrier, it is imperative to develop very rapid and sensitive hydrogen leaks sensors due to the highly explosive and flammable character of this gas. For this purpose, palladium-based materials are being widely investigated by research teams because of the high affinity between this metal and hydrogen. Furthermore, nanostructured palladium may provide improved sensing performances compared to the use of bulk palladium. This arises from a higher effective surface available for interaction of palladium with the hydrogen gas molecules. Several works taking advantage of palladium nanostructures properties for hydrogen sensing applications have been published. This paper reviews the recent advances reported in the literature in this scope. The electrical and optical detection techniques, most common ones, are investigated and less common techniques such as gasochromic and surface wave acoustic sensors are also addressed. Here, the sensor performances are mostly evaluated by considering their response time and limit of detection.

Due to their high potential in energy and environment domains, synthetic approach allowing fabrication of high quality boron nitride (BN) structures in a controlled manner is of great interest. Herein, a two‐step ammonia‐free atomic layer deposition approach to BN, based on polymer‐derived‐ceramics chemistry, is reported for the first time. Using trichloroborazine and hexamethyldisilazane as precursors, a conformal pre‐ceramic polymer layer is grown at low temperature, 80 °C, and then converted into dense hexagonal BN (h‐BN). The present approach allows conformal and homogeneous deposition of h‐BN films on various substrates with a thickness control at the atomic scale. It proves to be successful for fabricating various tuned BN nanostructures and composites that are efficient in water purification. In particular, the obtained nanostructures demonstrate high hydrophobicity and they are investigated as water filters for organic/water separation. Good separation efficiency is demonstrated that highlights the high potential of such atomic layer deposition (ALD) structures in water treatment.