Applied Nano

In this work, an eco-friendly 3D screen printing technique implemented in roll-to-roll technology for the manufacturing of flexible electronics is presented. The conductive ink was prepared through the decomposition of hydrogen peroxide, an eco-friendly reagent, onto the surfaces of silver nanoparticles. A biodegradable master pattern for screen printing was printed by 3D fused deposition modeling using a polylactic acid filament. This technique was implemented to fabricate hybrid touch-sensitive sensors, to be used as electrical switches, on both photographic and conventional office papers. The functionality of these sensors was demonstrated, and the systems were tested under aging and bending conditions, proving the reliability of this technological approach in flexible electronics and offering a biodegradable alternative.

The growing demand for environmentally friendly materials has driven extensive research into biopolymer-based nanocomposites with enhanced functional performance. Chitosan, a naturally derived polysaccharide, offers excellent film-forming ability, biodegradability, and antimicrobial potential, making it a promising matrix for sustainable packaging and coating applications. In this study, a distinctive solvent-casting strategy was employed to fabricate chitosan-based nanocomposite films functionalized with dual-action silver/titania (Ag/TiO₂) nanoparticles, combining both photocatalytic and metallic antimicrobial mechanisms—an approach that provides broader functionality than conventional single-component fillers. The biodegradable films were systematically characterized for their structural, mechanical, optical, and barrier properties, as well as their antimicrobial performance. The integration of Ag/TiO₂ imparted unique synergistic effects, modifying film morphology and color, slightly reducing tensile strength, and enhancing hydrophobicity and structural compactness. The obtained water vapor permeability values (0.013–0.102 g·mm·m⁻²·h⁻¹·kPa⁻¹) classified the materials as moderate barriers, comparable to or better than many existing chitosan-based systems without nanofiller reinforcement. Notably, films containing 10 wt% Ag/TiO₂ achieved a 40.4% reduction in Escherichia coli viability and an 8.2% inhibition of Staphylococcus aureus, demonstrating concentration-dependent antimicrobial activity superior to that of neat chitosan films. Overall, the unique combination of a biodegradable chitosan matrix with multifunctional Ag/TiO₂ nanofillers offers clear advantages over traditional biopolymer films, highlighting their potential as advanced materials for active food packaging and antimicrobial surface coatings.

Ultrafine bubbles (UFBs) have been proposed as interfacial agents that modulate colloidal interactions, yet their role in early-stage flocculation remains insufficiently quantified. Using amidine latex (AL) as a cationic model colloid under controlled end-over-end mixing, we combined flocculation kinetics with electrokinetic and interfacial measurements to elucidate the mechanism by which UFBs promote aggregation. Electrophoretic measurements show adsorption-driven charge regulation by bubbles; increasing the UFB-to-AL ratio progressively neutralizes the surface and at sufficient dose reverses its charge. The neutrality point occurs at a characteristic ratio that is only weakly sensitive to background sodium chloride (NaCl). Interfacial measurements reveal a thicker hydrodynamic layer at higher ionic strength, consistent with closer packing of adsorbed UFBs under double layer compression, and micrographs of particle dimers confirm a larger inter-particle separation that directly visualizes this layer. Aggregation accelerates at 10 mM sodium chloride but remains slow at 0.1 mM, indicating that electrolyte screening is required for efficient adsorption and bridging; pH modulated the process secondarily. Together, the results support a coherent picture in which UFB adsorption creates patchy, charge-compensated surfaces and a soft hydrodynamic layer that enlarges the effective collision cross-section, thereby enhancing early-stage flocculation.