A new strategy for oriented covalent immobilization of Trametes hirsuta laccase on gold electrodes is presented. The strategy is based on the gold surface modification with a mixed monolayer of an aromatic diazonium salt derivative and 6-mercapto-1-hexanol for further use as scaffold for the enzyme's covalent linkage. This strategy offers a variety of advantages such as high stability and laccase-friendly support morphology, which turns it into a suitable metal-enzyme interface. Conditions aiming at optimum orientation for direct electron transfer (DET) via the T1 copper site were studied.Current density values up to 40 µA·cm -2 were measured for the electrocatalytic reduction of O 2 in absence of redox mediators. This strategy is a big step forward in the development of laccase-modified gold electrodes for bioelectrocatalytic reduction of O 2 .

Macroporous poly(styrene-co-divinylbenzene) microparticles from reactive mixtures with various divinylbenzene and diluent contents have been synthesized. n-Heptane, which is a poor solvent for the copolymer, was used as diluent of the organic phase during the polymerization to obtain a high percentage of meso- and macropores, which are the most useful pores in the adsorption of macromolecules of medium and large sizes, such as proteins. The research was planned through a factorial design of experiments in an attempt to determine a quantitative relationship between the pore characteristics of the microparticles obtained and the concentration of the divinylbenzene and of the diluent used in the reactive mixture. The nitrogen adsorption−desorption isotherm and the curve of mercury intrusion for each type of microparticle were obtained, and the BET-specific surface areas and the volumes of macro-, meso-, and micropores were determined. Finally, empirical models correlating the synthesis conditions with the BET-specific surface area and the volumes of the micro-, meso-, and macropores were calculated; it was observed that the higher the divinylbenzene concentration in the monomeric mixture, the higher the volumes of micro- and mesopores and the larger the BET-specific surface area. It was also concluded that the higher the amount of diluent, the higher the volumes of meso- and macropores. Within the scope of the work, these models permit the synthesis of adsorbents with predetermined pore properties.

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The adsorption properties of macroporous polymeric microparticles are dependent on their porous structure, which, in turn, is dependent on the synthesis conditions of the adsorbent material. In the present work, we have investigated whether it is feasible to find a quantitative relationship between the synthesis conditions of macroporous poly(styrene-co-divinylbenzene) adsorbent microparticles and their behavior in the adsorption of a protein of intermediate size. For this purpose, 10 types of such microparticles were synthesized from reactive mixtures with different divinylbenzene (cross-linker) and n-heptane (diluent) contents, and the equilibrium isotherms and adsorption kinetics of a model protein (the bovine serum albumin (BSA) protein) were studied. The results allowed us to determine some quantitative relationships that, within the limits of this research, permit the synthesis of adsorbents with predetermined adsorption properties. Thus, the model obtained, relating the synthesis conditions of the adsorbents to the adsorption equilibrium, reveals that the higher the divinylbenzene concentration and the higher the diluent content, the higher the maximum adsorption capacity of the adsorbents for this protein. With regard to adsorption kinetics, the fastest adsorption was achieved with the lowest divinylbenzene concentration and the highest diluent concentration.

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The introduction of carbon nanotubes (CNTs) in structural fibre-reinforced polymers, to imbue the composite with multifunctional properties (e.g. enhancing electrical/thermal conductivity, structural health monitoring), has received much attention in recent years. Maintaining, and preferably enhancing, the structural integrity of the composite is imperative. Consequently, strong interfacial bonding between the CNTs and the polymer matrix is sought. If the sought multifunctionality is dependent on specific CNT alignment or orientation, achieved through fragile CNT assemblies, gas-phase chemical functionalisation of the CNT assembly is a viable approach in order to chemically modify the CNT surface without damaging the CNT assembly. This study reports on the gas-phase amino-functionalisation of CNT webs (CNTw) and further explores its influence on the in situ electrical conductivity. The placement of an ethylenediamine-functionalised multilayer CNTw (0.2 g•m-2) between CF plies resulted in a 13 % enhancement in the interlaminar Mode I fracture toughness, while providing an electrical conductivity of 10 3 S•m-1 in the direction of the CNTs within the interleaved CNTw. The effectiveness of the aminofunctionalised CNTw in enhancing the mechanical properties of an epoxy composite is related to an epoxy opening reaction, as demonstrated by Differential Scanning Calorimetry (DSC). Raman and X-ray photoelectron spectroscopies are used to confirm that gas-phase amino-functionalisation does not damage the graphene-based structure and its structural dependent properties.

A simple carbon nanodot–based electrogenerated chemiluminescence biosensor is described for sensitive and selective detection of microRNA-21 (miRNA-21), a biomarker of several pathologies including cardiovascular diseases (CVDs). The photoluminescent carbon nanodots (CNDs) were obtained using a new synthesis method, simply by treating tiger nut milk in a microwave reactor. The synthesis is environmentally friendly, simple, and efficient. The optical properties and morphological characteristics of the CNDs were exhaustively investigated, confirming that they have oxygen and nitrogen functional groups on their surfaces and exhibit excitation-dependent fluorescence emission, as well as photostability. They act as co-reactant agents in the anodic electrochemiluminescence (ECL) of [Ru(bpy)3]2+, producing different signals for the probe (single-stranded DNA) and the hybridized target (double-stranded DNA). These results paved the way for the development of a sensitive ECL biosensor for the detection of miRNA-21. This was developed by immobilization of a thiolated oligonucleotide, fully complementary to the miRNA-21 sequence, on the disposable gold electrode. The target miRNA-21 was hybridized with the probe on the electrode surface, and the hybridization was detected by the enhancement of the [Ru(bpy)3]2+/DNA ECL signal using CNDs. The biosensor shows a linear response to miRNA-21 concentration up to 100.0 pM with a detection limit of 0.721 fM. The method does not require complex labeling steps, and has a rapid response. It was successfully used to detect miRNA-21 directly in serum samples from heart failure patients without previous RNA extraction neither amplification process. Graphical abstract

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