Dr. Adrian ENACHE

Over the past decades, extensive research has demonstrated and confirmed the antioxidant potency of polyphenols, which due to these properties, are now widely recognized for their ability to enhance cell viability. This study investigates the antioxidant capacity of seven green leafy vegetables on in vitro mouse (L929) and human (BJ) fibroblast cell lines, aiming to determine if polyphenols could aid the regeneration of connective tissue, which would be strongly beneficial in wound healing and tissue repair, a process where fibroblast thriving is essential. The antioxidant capacity of extracts was investigated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, UV-Vis spectroscopy, and amperometry, with quercetin serving as a standard. The EC50 values for the extracts were equivalent to approximately 5 mu M quercetin, derived from a concentration range of 20 to 100 mg of fresh leaves per mL. In vitro investigations revealed that all extracts, except lovage, promoted high viability (over 80%) in both cell cultures, as shown by MTS assay results and fluorescence microscopy. Additionally, Tumor Necrosis Factor (TNF)-alpha and Lipopolysaccharide (LPS) were employed as reactive oxygen species (ROS) antagonists, and the Dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay was used to demonstrate the extract's scavenging activity on fibroblasts in vitro. For some extracts, a reduction in oxidative stress compared to the cells basal metabolic conditions was observed.

In this paper, graphene was obtained on a copper substrate using the CVD method, and then it was transferred to various substrates such as glass and SiO2/Si patterned with metallic interdigitated electrodes. The graphene thus obtained was characterized using Raman spectroscopy, scanning electron microscopy (SEM), current-voltage measurements, and electrochemical methods, in order to be used for sensing applications.

A novel electrochemical biosensor was developed to monitor fibroblast cells stress levels for the first time in situ under external stimuli based on the recognition of superoxide anion released upon cell damage. The biosensor comprised metallized polycaprolactone electrospun fibers covered with zinc oxide for improved cell adhesion and signal transduction, whilst stable bioconjugates of mercaptobenzoic acid-functionalized gold nanoparticles/ superoxide dismutase were employed as recognition bioelements. Biosensors were first tested and optimized for in situ generated superoxide detection by fixed potential amperometry at +0.3 V, with minimal interferences from electroactive species in cell culture media. L929 fibroblast cells were then implanted on the optimized biosensor surface and the biosensor morphologically characterized by scanning electron microscopy (SEM) and fluorescence microscopy, which illustrated the network-type pattern of fibroblasts adjacent to the fiber scaffold. Fibroblast stress was induced by zymosan and monitored at the cells integrated biosensor using fixed potential amperometry (CA) with a sensitivity of 26 nA cm-2 mu g mL-1 zymosan and electrochemical impedance spectros-copy (EIS), with similar sensitivity of the biosensor considering the Rs and Z' parameters of around 0.13 omega cm2 mu g-1 mL and high correlation factors R2 of 0.9994. The obtained results underline the applicability of the here developed biosensor for the electrochemical screening of the fibroblast cells stress. The concept in using low-cost biocompatible polymeric fibers as versatile scaffolds for both enzyme immobilization and cell adhesion, opens a new path in developing biosensors for the in-situ investigation of a variety of cellular events.

Three-dimensional graphene foam (3D-GrFoam) is a highly porous structure and sustained lattice formed by graphene layers with sp(2) and sp(3) hybridized carbon. In this work, chemical vapor deposition (CVD)-grown 3D-GrFoam was nitrogen-doped and platinum functionalized using hydrothermal treatment with different reducing agents (i.e., urea, hydrazine, ammonia, and dihydrogen hexachloroplatinate (IV) hydrate, respectively). X-ray photoelectron spectroscopy (XPS) survey showed that the most electrochemically active nitrogen-doped sample (GrFoam3N) contained 1.8 at % of N, and it exhibited a 172 mV dec(-1) Tafel plot associated with the Volmer-Heyrovsky hydrogen evolution (HER) mechanism in 0.1 M KOH. By the hydrothermal process, 0.2 at % of platinum was anchored to the graphene foam surface, and the resultant sample of GrFoamPt yielded a value of 80 mV dec(-1) Tafel associated with the Volmer-Tafel HER mechanism. Furthermore, Raman and infrared spectroscopy analysis, as well as scanning electron microscopy (SEM) were carried out to understand the structure of the samples.