Graphene setting the stage: tracking DNA hybridization with nanoscale resolution

In this study we use nanophotonic effects of graphene to study DNA hybridization: the z−4 nanoscale distance-dependence of the fluorescence lifetime for fluorophores located in the vicinity of graphene is for the first time used to track a DNA hybridization reaction with nanoscale resolution in real time. First, a nanostaircase with ≈2 nm steps from 0 to a total height of 48 nm is used as a nanoruler to confirm the distance dependence law. We find that the axial sensitivity is suited to determine the nanoscale surface roughness of these samples. The proof-of-concept DNA experiments in aqueous medium involve the hybridization of fluorescently labelled DNA beacons attached to CVD grown graphene with complementary (target) DNA added in solution. We track the conformational changes of the beacons statistically by determining the fluorescence lifetimes of the labelling dye and converting them into nanoscale distances from the graphene. In this way, we are able to monitor the vertical displacement of the label during DNA-beacon unfolding with an axial resolution reaching down to 1 nm. The measured distance increase during the DNA hybridization reaction of about 10 nm matches the length of the target DNA strand. Furthermore, the width of the fluorescence lifetime distributions could be used to estimate the molecular tilt angle of the hybridized ds-DNA configuration. The achieved nanoscale sensitivity opens innovation opportunities in material engineering, genetics, biochemistry and medicine.INL received support for this project from the CCDR-N via the project 'Nanotechnology based functional solutions' (Grant No. NORTE-01-0145-FEDER-000019) and from the Portuguese Foundation for Science and Technology (FCT) via the project 'ON4SupremeSens' PTDC/NAN-OPT/29417/2017. Edite Figueiras received a Marie Curie fellowship via the EU-EC COFUND program 'NanoTRAINforGrowth' (Grant No. 600375). U Minho research was partially supported by the FCT in the framework of the Strategic Funding UID/FIS/04650/2013

Spectral-temporal luminescence properties of Colloidal CdSe/ZnS Quantum Dots in relevant polymer matrices for integration in low turn-on voltage AC-driven LEDs

This work employs spectral and spectral-temporal Photoluminescence (PL) spectroscopy techniques to study the radiative mechanisms in colloidal CdSe/ZnS Quantum Dot (QD) thin films without and with 1% PMMA polymer matrix embedding (QDPMMA). The observed bimodal transient-spectral PL distributions reveal bandgap transitions and radiative recombinations after interdot electron transfer. The PMMA polymer embedding protects the QDs during the plasma-sputtering of inorganic layers electroluminescent (EL) devices, with minimal impact on the charge transfer properties. Further, a novel TiO2-based, all-electron bandgap, AC-driven QLED architecture is fabricated, yielding a surprisingly low turn-on voltage, with PL-identical and narrow-band EL emission. The symmetric TiO2 bilayer architecture is a promising test platform for alternative optical active materials.European Commission, Seventh Framework Programme (600375); European Commission, Horizon 2020 Framework Programme (828841); European Regional Development Fund, INTERREG V-A España-Portugal (POCTEP) 2014-2020 (0181_NANOEATERS_1_EP); CCDR-N (NORTE-01-0145-FEDER-000019); Fundação para a Ciência e a Tecnologia (UIDB/04650/2020)

Oscillator Finite-Difference Time-Domain (O-FDTD) electric field propagation model: integrated photonics and networks

The recently developed Lorentz Oscillator Model-inspired Oscillator Finite-Difference Time-Domain (O-FDTD) is one of the simplest FDTD models ever proposed, using a single field equation for electric field propagation. We demonstrate its versatility on various scales and benchmark its simulation performance against theory, conventional FDTD simulations, and experimental observations. The model’s broad applicability is demonstrated for (but not limited to) three contrasting realms: integrated photonics components on the nano- and micrometer scale, city-wide propagating radiofrequency signals reaching into the hundreds of meters scale, and for the first time, in support of 3D optical waveguide design that may play a key role in neuromorphic photonic computational devices

Cityscape LoRa signal propagation predicted and tested using real-world building-data based O-FDTD simulations and experimental characterization

The age of the Internet of Things (IoT) and smart cities calls for low-power wireless communication networks, for which the Long-Range (LoRa) is a rising star. Efficient network engineering requires the accurate prediction of the Received Signal Strength Indicator (RSSI) spatial distribution. However, the most commonly used models either lack the physical accurateness, resolution, or versatility for cityscape real-world building distribution-based RSSI predictions. For this purpose, we apply the 2D electric field wave-propagation Oscillator Finite-Difference Time-Domain (O-FDTD) method, using the complex dielectric permittivity to model reflection and absorption effects by concrete walls and the receiver sensitivity as the threshold to obtain a simulated coverage area in a 600 × 600 m2 square. Further, we report a simple and low-cost method to experimentally determine the signal coverage area based on mapping communication response-time delays. The simulations show a strong building influence on the RSSI, compared against the Free-Space Path (FSPL) model. We obtain a spatial overlap of 84% between the O-FDTD simulated and experimental signal coverage maps. Our proof-of-concept approach is thoroughly discussed compared to previous works, outlining error sources and possible future improvements. O-FDTD is demonstrated to be most promising for both indoors and outdoors applications and presents a powerful tool for IoT and smart city planners.European Commission | Ref. 0181 NANOEATERS 1 EPComissão de Coordenação e Desenvolvimento Regional do Norte (Portugal) | Ref. NORTE-01-0145-FEDER-000019European Commission | Ref. FETOPEN-01-2018-2019-2020, n. 828841Xunta de Galicia | Ref. ED431B 2018/57Ministerio de Economía, Industria y Competitividad (España) | Ref. FIS2017-83762-

A rationally identified marine GH1 β‐glucosidase has distinguishing functional features for simultaneous saccharification and fermentation

The classical route for second‐generation ethanol from lignocellulosic biomass is hampered by high process costs, fostering the development of alternative strategies such as simultaneous saccharification and fermentation (SSF). However, the lack of compatible enzyme cocktails poses a challenge. In this study, the enzyme EmBgl from the marine bacterium Exiguobacterium marinum was rationally identified based on structural and phylogenetic analyses, known desirable properties of close orthologs, and the ecological niche of its organism source. EmBgl is a multifunctional and glucose‐tolerant enzyme that efficiently hydrolyzes cello‐oligosaccharides due to a positive‐subsite region that can accommodate long cello‐oligosaccharides without imposing steric impediments. The efficacy of EmBgl in an SSF process was demonstrated using pretreated sugarcane bagasse as feedstock, yielding 28 g L−1 of ethanol in 30 h. The distinguishing functional properties of EmBgl and its successful utilization in an SSF process highlight its potential in biotechnological applications in which lignocellulose deconstruction is desirable under milder temperatures14611631179FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP17/14253‐9; 16/19995‐0; 16/06509‐0; 19/08855‐1; 15/26982‐0; 18/02865‐2; 16/06509‐0; 16/19995‐0; 17/14253‐9; 18/02865‐2; 15/26982‐0; 19/08855‐