Nanomaterials

Photothermal therapy (PTT) is an emerging non-invasive treatment for cancer, offering targeted, localized therapy with minimal side effects. Its growing significance lies in its ability to precisely heat and destroy tumor cells while sparing surrounding healthy tissue. This study aimed to validate the $\delta P1$ approximation for simulating light propagation and thermal effects in biological tissues, particularly for photothermal therapy (PTT) applications. The model is applied to various scenarios, including homogeneous and heterogeneous tissue geometries with different optical properties and nanoparticle concentrations. The results are compared with analytical solutions, Monte Carlo results and experimental data to assess model accuracy. The $\delta P1$ approximation demonstrates superior performance compared to Beer–Lambert and Standard diffusion models, accurately predicting temperature distributions and capturing the influence of heterogeneous geometries. These findings highlight the potential of the $\delta P1$ model to significantly advance the field of PTT by providing reliable predictions for treatment planning and optimization.

CrAlSiN nanocomposite coatings with different structures were prepared by arc ion plating. The influence of substrate bias on the composition, microstructure and properties of the coating was investigated. The nanocomposite CrAlSiN coatings all had a fcc-(Cr, Al)N phase, where Al atoms and some Si atoms were solid-dissolved in CrN phase and some Si existed in the form of amorphous phase in the coating. The coatings were preferentially grown along the (200) crystal plane. With the increase in substrate bias, the roughness of the coating gradually decreased. When the substrate bias gradually increased to 100 V, the small particles aggregated into large particles, producing more holes, so that the surface roughness of the coating increased. At the same time, with the increase in substrate bias, the hardness and adhesion of the coating first increased and then decreased. When the substrate bias voltage was 80 V, the coating had the largest hard H (31.30 GPa), elastic modulus E* (432.15 GPa), H/E* (0.0724), H³/E*² (0.1642) and binding force of 109.26 N.

Silver nanoparticles were biosynthesized using the culture supernatant of Staphylococcus sp. YRA, a strain isolated from Colombian mining sediments. Synthesis was optimized at 1 mM AgNO₃, pH 7, 40 °C and 7 μg/mL extract, producing spherical, protein-capped AgNPs with primary sizes in the tens-of-nanometers range (~35–90 nm by SEM), while DLS indicated larger hydrodynamic diameters (~250–320 nm) consistent with aggregation in suspension (ζ-potential −16.6 mV). These nanoparticles remained stable over 6 months. Characterization by UV–Vis, SEM, AFM, EDS and FTIR confirmed extracellular protein-mediated reduction and capping. The AgNPs showed antibacterial activity against multidrug-resistant clinical isolates (Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Salmonella bongori, Enterococcus spp.), with inhibition zones of 8–16 mm at 400–1000 μg/mL. Biofilm formation was reduced by >50% at 700 μg/mL in both Gram-positive and Gram-negative strains. In Phaseolus vulgaris (P. vulgaris), low concentrations (5–100 μg/mL) increased growth and chlorophyll content, while 500 μg/mL caused moderate inhibition. FTIR analysis identified amide and thiol groups from bacterial enzymes as capping agents. These results suggest Staphylococcus sp. YRA as a bacterial platform for AgNPs production with antibiofilm activity against MDR pathogens and acceptable phytotoxicity profile for potential applications.