Facile Gram-Scale Synthesis of NiO Nanoflowers for Highly Selective and Sensitive Electrocatalytic Detection of Hydrazine.

The design and development of efficient and electrocatalytic sensitive nickel oxide nanomaterials have attracted attention as they are considered cost-effective, stable, and abundant electrocatalytic sensors. However, although innumerable electrocatalysts have been reported, their large-scale production with the same activity and sensitivity remains challenging. In this study, we report a simple protocol for the gram-scale synthesis of uniform NiO nanoflowers (approximately 1.75 g) via a hydrothermal method for highly selective and sensitive electrocatalytic detection of hydrazine. The resultant material was characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. For the production of the modified electrode, NiO nanoflowers were dispersed in Nafion and drop-cast onto the surface of a glassy carbon electrode (NiO NF/GCE). By cyclic voltammetry, it was possible to observe the excellent performance of the modified electrode toward hydrazine oxidation in alkaline media, providing an oxidation overpotential of only +0.08 V vs Ag/AgCl. In these conditions, the peak current response increased linearly with hydrazine concentration ranging from 0.99 to 98.13 µmol L-1. The electrocatalytic sensor showed a high sensitivity value of 0.10866 µA L µmol-1. The limits of detection and quantification were 0.026 and 0.0898 µmol L-1, respectively. Considering these results, NiO nanoflowers can be regarded as promising surfaces for the electrochemical determination of hydrazine, providing interesting features to explore in the electrocatalytic sensor field.

Hyaluronic acid hydrogels reinforced with laser spun bioactive glass micro- and nanofibres doped with lithium.

The repair of articular cartilage lesions in weight-bearing joints remains as a significant challenge due to the low regenerative capacity of this tissue. Hydrogels are candidates to repair lesions as they have similar properties to cartilage extracellular matrix but they are unable to meet the mechanical and biological requirements for a successful outcome. Here, we reinforce hyaluronic acid (HA) hydrogels with 13-93-lithium bioactive glass micro- and nanofibres produced by laser spinning. The glass fibres are a reinforcement filler and a platform for the delivery of therapeutic lithium-ions. The elastic modulus of the composites is more than three times higher than in HA hydrogels. Modelling of the reinforcement corroborates the experimental results. ATDC5 chondrogenic cells seeded on the composites are viable and more proliferation occurs on the hydrogels containing fibres than in HA hydrogels alone. Furthermore, the chondrogenic behavior on HA constructs with fibres containing lithium is more marked than in hydrogels with no-lithium fibres.

Controlling cancer cell fate using localized biocatalytic self-assembly of an aromatic carbohydrate amphiphile.

We report on a simple carbohydrate amphiphile able to self-assemble into nanofibers upon enzymatic dephosphorylation. The self-assembly can be triggered by alkaline phosphatase (ALP) in solution or in situ by the ALP produced by osteosarcoma cell line, SaOs2. In the latter case, assembly and localized gelation occurs mainly on the cell surface. The gelation of the pericellular environment induces a reduction of the SaOs2 metabolic activity at an initial stage (≤7 h) that results in cell death at longer exposure periods (≥24 h). We show that this effect depends on the phosphatase concentration, and thus, it is cell-selective with prechondrocytes ATDC5 (that express ∼15-20 times lower ALP activity compared to SaOs2) not being affected at concentrations ≤1 mM. These results demonstrate that simple carbohydrate derivatives can be used in an antiosteosarcoma strategy with limited impact on the surrounding healthy cells/tissues.