The incorporation of bactericidal properties into textiles is a widely sought-after aspect, and silver nanoparticles (AgNPs) can be used for this. Here, we evaluate a strategy for incorporating AgNPs into a cotton fabric. For this purpose, a bactericidal textile coating based on a composite of AgNPs and kappa-carrageenan (k-CA) was proposed. The composite was obtained by heating the silver precursor (AgNO₃) directly in k-CA solution for green synthesis and in situ AgNPs stabilization. Cotton substrates were added to the heated composite solution for surface impregnation and hydrogel film formation after cooling. Direct synthesis of AgNPs on a fabric was also tested. The results showed that the application of a coating based on k-CA/AgNPs composite can achieve more than twice the silver loading on the fabric surface compared to the textile subjected to direct AgNPs incorporation. Furthermore, silver release tests in water showed that higher Ag⁺ levels were reached for k-CA/AgNPs-coated cotton. Therefore, inoculation tests with the bacteria Staphylococcus aureus (SA) using the agar diffusion method showed that samples covered with the composite resulted in significantly larger inhibition halos. This indicated that the use of the composite as a coating for cotton fabric improved its bactericidal activity against SA.

HER2 antigen is a marker used for breast cancer diagnosis and prevention. Its determination has great importance since breast cancer is one of the most insidious types of cancer in women. HER2 antigen assessment in human serum is traditionally achieved by enzyme-linked immunosorbent assay (ELISA method), but it has some disadvantages, such as suppressing the thermodynamic–kinetic studies regarding the antibody–antigen interaction, and the use of labeled molecules that can promote false positive responses. Biosensors based on surface plasmon resonance (SPR) are sensitive optical techniques widely applied on bioassays. The plasmonic devices do not operate with labeled molecules, overcoming conventional immunoassay limitations, and enabling a direct detection of target analytes. In this way, a new SPR biosensor to assess HER2 antigen has been proposed, using nanohole arrays on a gold thin film by signal transduction of transmitted light measurements from array image acquisitions. These metallic nanostructures may couple the light directly on surface plasmons using a simple collinear arrangement. The proposed device reached an average sensitivity for refractive index (RI) variation on a metal surface of 4146 intensity units/RIU (RIU = RI units). The device feasibility on biomolecular assessment was evaluated. For this, 3 ng ml ⁻¹ known HER2 antigen concentration was efficiently flowed (using a microfluidic system) and detected from aqueous solutions. This outcome shows that the device may be a powerful apparatus for bioassays, particularly toward breast cancer diagnosis and prognosis.

Packaging composed of polysaccharides has emerged as an alternative to petroleum-based commercial products. Thus, this research aimed to develop, optimize, characterize, and apply biodegradable pectin/starch-based films for fresh pears. All film-forming formulations were characterized. Digital images and optical properties suggest stable, transparent, and efficient ultraviolet (UV) blocking films, especially UVC-UVB and partially UVA. Thermal analysis indicated significant mass loss at high temperatures (above 250 °C). The films were permeable to water vapor (0.305–0.255 g × mm/h × m² × kPa) and impermeable to oil. Scanning electron microscopy revealed surface and cross-sectional changes in the material that influenced its mechanical properties, including tensile strength (0.029–0.041 MPa), Young’s modulus (1.42–2.21 MPa), and elongation at break (1.69–2.98%). The films showed a water solubility of around 74% (w/w) with a maximum swelling of 233%. In addition, statistical tools facilitated optimization and data interpretation. The Simplex lattice mixture design indicated that the film containing 100% pectin (Pec-100) was more resistant and less permeable to water vapor, while principal component analysis attributed high transparency and rigidity. In this sense, the Pec-100 material showed potential for film application on fresh pears. Digital images recorded during storage suggested that coated fruits appeared fresh after 15 days. On the other hand, uncoated pears displayed degradation points starting from the tenth day. Therefore, the renewable-source-based film demonstrated promising fruit preservation results.