Marta M. Alves

NDAu green-synthesised via Nymphaea alba root extracts show high biocompatibility and tunable surface chemistry. Biological assays in A549 lung carcinoma cells confirmed efficient uptake and good biocompatibility, particularly for oxidized NDAu.

The increasing consumption of fish products has resulted in significant waste generation, with sardine scales (Sardina pilchardus) representing a notable by-product of the canning industry. This work investigates the sustainable valorization of these scales through collagen extraction for applications in cosmetics and nutrition. Collagen was extracted using acid and pepsin-assisted methods and characterized by spectroscopic and imaging techniques (UV–Vis, FTIR, PXRD, SEM, and SDS-PAGE). Subsequent enzymatic hydrolysis with papain produced low-molecular-weight peptides. Biological assays revealed enhanced antioxidant activity of the hydrolyzed peptides compared to native collagen, while no antimicrobial effects were detected. Permeation studies in Caco-2 cells indicated moderate intestinal absorption (~6.4% in 6 h). These findings support the potential of sardine-derived collagen as a bioactive ingredient aligned with circular economy principles.

This study determined the feasibility of using zinc oxide nanoparticles of various origins as an active compound for biopolymer packaging films. The study focused on the effects of green synthesis using passion fruit or tomato extracts and commercial zinc oxide nanoparticles on the physicochemical properties of pectin films, including thickness, microstructure, water content, optical properties, water vapour permeability, water contact angle, sorption properties, and thermal stability. Zinc oxide nanoparticles resulted in lower lightness, higher absorbance, especially in the UV light range, and increased transparency, from 1.55 to 2.18 a.u./mm. Films containing zinc oxide nanoparticles showed reduced water vapour adsorption but increased water vapour permeability, from 6.35 to 12.07 × 10⁻¹⁰ g/m·s·Pa. The initial water contact angles were in a similar range, from 57.3° to 59.2°, but a decrease in contact angle values was observed over 60 s. All films containing nanoparticles exhibited better thermal stability, particularly during the third stage of degradation above 200 °C. Developed composite active films, prepared from apple pectin and zinc oxide nanoparticles of different origins, showed their potential for practical use as UV-VIS light barrier packaging films or protective coatings for food applications.

In this work the synthesis and characterization of novel gold-nanodiamond nanoparticles was performed. The synthesis was based on the reduction of gold onto the different types of nanodiamond (annealed or annealed and oxidized, 50 or 230 nm) using root extracts of Nympheaea alba as a reducing agent. These gold-coated nanodiamonds were characterized by UV-Vis, PXRD, DLS, zeta-potential, PIXE, Raman, SEM, and TEM, assessing particle size, stability, and gold coating effectiveness. Cellular studies in the A549 and Panc1 cancer cell lines assessed uptake, cytotoxicity, and colony formation to evaluate NDAu's biological activity. NDAu demonstrated strong cellular uptake and cytotoxic effects in A549 and Panc1 cell lines, reducing cell survival in clonogenic assay. Futher research in the capabilites of these nanoparticles for proton therapy will be performed.

Hydroxyapatite (HAp) is a widely used biocompatible material in orthopedic composite preparations. However, HAp composites that exhibit both anticancer and antibacterial activities through bioactive coordination complexes are relatively rare. To explore orthopedic applications, we blended several silver camphorimine compounds with HAp to create [Ag(I)] composites. All compounds [Ag(NO₃)(L)_n] (n = 1,2) based on camphorimine (L^A), camphor sulfonimine (L^B) or imine bi-camphor (L^C) ligands demonstrated significant cytotoxic activity (IC₅₀ = 0.30–2.6 μg_Ag/mL) against osteosarcoma cancer cells (HOS). Based on their structural and electronic characteristics, four complexes (1–4) were selected for antibacterial evaluation against Escherichia coli, Burkholderia contaminans, Pseudomonas aeruginosa, and Staphylococcus aureus. All complexes (1–4) revealed combined anticancer and antibacterial activities; therefore, they were used to prepare [Ag(I)]:HAp composites of 50:50% and 20:80% weight compositions and the activities of the composites were assessed. Results showed that they retain the dual anticancer and antibacterial characteristics of their precursor complexes. To replicate the clinical context of bone-filling applications, hand-pressed surfaces (pellets) were prepared. It is worth highlighting that no agglutination agent was necessary for the pellet’s consistency. The biological properties of the so-prepared pellets were assessed, and the HOS cells and bacteria spreading on the pellet’s surface were analyzed by SEM. Notably, composite 4B, derived from the bicamphor (L^C) complex [Ag(NO₃)(OC₁₀H₁₄N(C₆H₄)₂NC₁₀H₁₄O)], exhibited significant anticancer activity against HOS cells and antibacterial activity against P. aeruginosa, fostering potential clinical applications on post-surgical OS treatment.

This research investigates pH changes during the green synthesis of ZnO nanoparticles (NPs) and emphasises its importance in their physicochemical, antibacterial, and biological properties. Varying the synthesis pH from 8 to 12 using “Bravo de Esmolfe” apple extracts neither affected the morphology nor crystallinity of ZnO but impacted NP phytochemical loads. This difference is because alkaline hydrolysis of phytochemicals occurred with increasing pH, resulting in BE-ZnO with distinct phytocargos. To determine the toxicity of BE-ZnO NPs, Galleria mellonella was used as an alternative to non-rodent models. These assays showed no adverse effects on larvae up to a concentration of 200 mg/kg and that NPs excess was relieved by faeces and silk fibres. This was evaluated by utilising fluorescence-lifetime imaging microscopy (FLIM) to track NPs’ intrinsic fluorescence. The antibacterial efficacy against Staphylococcus aureus was higher for BE-ZnO₁₂ than for BE-ZnO₈; however, a different trend was attained in an in vivo infection model. This result may be related to NPs’ residence in larvae haemocytes, modulated by their phytocargos. This research demonstrates, for the first time, the potential of green synthesis to modulate the biosafety and antibacterial activity of NPs in an advanced G. mellonella infection model. These findings support future strategies to overcome antimicrobial resistance by utilizing distinct phytocargos to modulate NPs’ action over time.