Enhanced performance of impedimetric immunosensors to detect SARS-CoV-2 with bare gold nanoparticles and graphene acetic acid.

Immunosensors based on electrical impedance spectroscopy allow for label-free, real-time detection of biologically relevant molecules and pathogens, without requiring electro-active materials. Here, we investigate the influence of bare gold nanoparticles (AuNPs), synthesized via laser ablation in solution, on the performance of an impedimetric immunosensor for detecting severe acute respiratory syndrome coronavirus (SARS-CoV-2). Graphene acetic acid (GAA) was used in the active layer for immobilizing anti-SARS-CoV-2 antibodies, owing to its high density of carboxylic groups. Immunosensors incorporating AuNPs exhibited superior performance compared to those relying solely on GAA, achieving a limit of detection (LoD) of 3 x 10-20 g/mL to detect the Spike Receptor Binding Domain (RBD) protein of SARS-CoV-2 and of 2 PFU/mL for inactivated virus. Moreover, these immunosensors presented high selectivity against the H1N1 influenza virus. We anticipate that this platform will be versatile and applicable in the early diagnosis of various diseases and viral infections, thereby facilitating Point-of-Care testing.

Melittin sensitizes skin squamous carcinoma cells to 5-fluorouracil by affecting cell proliferation and survival.

Combined 5-fluorouracil (5-FU) and melittin (MEL) is believed to enhance cytotoxic effects on skin squamous cell carcinoma (SCC). However, the rationale underlying cytotoxicity is fundamentally important for a proper design of combination chemotherapy, and to provide translational insights for future therapeutics in the dermatology field. The aim was to elucidate the effects of 5-FU/MEL combination on the viability, proliferation and key structures of human squamous cell carcinoma (A431). Morphology, plasma membrane, DNA, mitochondria, oxidative stress, cell viability, proliferation and cell death pathways were targeted for investigation by microscopy, MTT, trypan blue assay, flow cytometry and real-time cell analysis. 5-FU/MEL (0.25 µM/0.52 µM) enhanced the cytotoxic effect in A431 cells (74.46%, p < .001) after 72 h exposure, showing greater cytotoxic effect when compared to each isolated compound (45.55% 5-FU and 61.78% MEL). The results suggest that MEL induces plasma membrane alterations that culminate in a loss of integrity at subsequent times, sensitizing the cell to 5-FU action. DNA fragmentation, S and G2/M arrest, disruption of mitochondrial metabolism, and alterations in cell morphology culminated in proliferation blockage and apoptosis. 5-FU/MEL combination design optimizes the cytotoxic effects of each drug at lower concentrations, which may represent an innovative strategy for SCC therapy.

Tumor cell death in orthotopic breast cancer model by NanoALA: a novel perspective on photodynamic therapy in oncology.

Aim: Nano-5-aminolevulic acid (NanoALA)-mediated photodynamic therapy (PDT), an oil-in-water polymeric nanoemulsion of ALA, was evaluated in a murine model of breast cancer. Materials & methods: Analysis of ALA-derived protoporphyrin IX production and acute toxicity test, biocompatibility and treatment efficacy, and long-term effect of NanoALA-PDT on tumor progression were performed. Results: The nanoformulation favored the prodrug uptake by tumor cells in a shorter time (1.5 h). As a result, the adverse effects were negligible and the response rates for primary mammary tumor control were significantly improved. Tumor progression was slower after NanoALA-PDT treatment, providing longer survival. Conclusion: NanoALA is a good proactive drug candidate for PDT against cancer potentially applied as adjuvant/neoadjuvant intervention strategy for breast cancer.