Photo-responsive antibacterial surfaces combining both on-demand photo-switchable activity and sustained biocidal release were prepared using sequential chemical grafting of nano-objects with different geometries and functions. The multi-layered coating developed incorporates a monolayer of near-infrared active silica-coated gold nanostars (GNS) decorated by silver nanoparticles (AgNP). This modular approach also enables us to unravel static and photo-activated contributions to the overall antibacterial performance of the surfaces, demonstrating a remarkable synergy between these two mechanisms. Complementary microbiological and imaging evaluations on both planktonic and surface-attached bacteria provided new insights on these distinct but cooperative effects.

Prussian blue (PB) is a coordination polymer based on the Fe^2+…CN^…Fe³⁺ sequence. It is an FDA-approved drug, intended for oral use at the acidic pH of the stomach and of most of the intestine track. However, based on FDA approval, a huge number of papers proposed the use of PB nanoparticles (PBnp) under "physiological conditions", meaning pH buffered at 7.4 and high saline concentration. While most of these papers report that PBnp are stable at this pH, a small number of papers describes instead PBnp degradation at the same or similar pH values, i.e. in the 7-8 range. Here we give a definitively clear picture: PBnp are intrinsically unstable at pH ≥ 7, degrading with the fast disappearance of their 700 nm absorption band, due to the formation of OH^- complexes from the labile Fe³⁺ centers. However, we show also that the presence of a polymeric coating (PVP) can protect PBnp at pH 7.4 for over 24 h. Moreover, we demonstrate that when "physiological conditions" include serum, a protein corona is rapidly formed on PBnp, efficiently avoiding degradation. We also show that the viability of PBnp-treated EA.hy926, NCI-H1299, and A549 cells is not affected in a wide range of conditions that either prevent or promote PBnp degradation.

The global threat of antimicrobial resistance is driving an urgent need for novel antimicrobial strategies. Functional surfaces are essential to prevent spreading of infection and reduce surface contamination. In this study we have fabricated and characterized multiscale-functional nanotopographies with three levels of functionalization: (1) nanostructure topography in the form of silicon nanowires, (2) covalent chemical modification with (3-aminopropyl)triethoxysilane, and (3) incorporation of chlorhexidine digluconate. Cell viability assays were carried out on two model microorganisms E. coli and S. aureus over these nanotopographic surfaces. Using SEM we have identified two growth modes producing distinctive multicellular structures, i.e. in plane growth for E. coli and out of plane growth for S. aureus. We have also shown that these chemically modified SiNWs arrays are effective in reducing the number of planktonic and surface-attached microorganisms.

Pancreatic ductal adenocarcinoma (PDAC) tumors exhibit pronounced phenotypic plasticity, alternating between a treatment-sensitive classical phenotype and a more aggressive basal-like state associated with drug resistance and poor prognosis. The frequent coexistence of these phenotypes complicates patient stratification and the selection of effective therapies. Tumor-derived organoids are valuable tools for drug screening; however, their clinical relevance relies on how accurately they recapitulate the phenotypic and functional characteristics of the original tumors. In this study, we present a quantitative analysis of how hydrogel composition influences the phenotype, tissue remodeling, metabolism, and drug resistance of PDAC organoids. Organoids were cultured within three types of hydrogels: Matrigel, collagen-I, and a mixture of collagen-I and Matrigel. Our results demonstrate that: (i) PDAC organoids grown in Matrigel exhibit a classical phenotype, with metabolic and drug response profiles similar to those of low-physiological two-dimensional cultures; (ii) Organoids grown in collagen-containing hydrogels, particularly those in collagen-Matrigel composites, faithfully recapitulate basal-like tumors, characterized by epithelial-to-mesenchymal transition, tissue remodeling, metabolic activity, and drug resistance; (iii) TGFβ induces an exacerbated, highly invasive basal-like phenotype. Summarizing, our findings highlight the importance of 3D hydrogel composition in modulating PDAC organoid phenotype and behavior and suggest collagen-Matrigel hydrogels as the most suitable matrix for modeling PDAC biology.

This paper discusses the feasibility of a novel strategy based on the combination of bioprinting nano-doping technology and LA-ICP-ToF-MS analysis for the preparation and characterisation of gelatin-based multi-element calibration standards suitable for quantitative imaging. To achieve this, lanthanide up-conversion nanoparticles were added to a gelatin matrix to produce the bioprinted calibration standards. The features of this bioprinting approach were compared with manual cryosectioning standard preparation, in terms of throughput, between batch repeatability and elemental signal homogeneity at 5 μm spatial resolution. By using bioprinting, the between batch variability for three independent standards of the same concentration of ⁸⁹Y (concentration range 0-600 mg/kg) was reduced to 5% compared to up to 27% for cryosectioning). On this basis, the RSD obtained between three independent calibration slopes measured within one day also reduced from 16% (using cryosectioning) to 5% (using bioprinting), supporting the use of a single standard preparation replicate for each of the concentrations to achieve good calibration performance using bioprinting. This helped reduce the analysis time by approximately 3-fold. With cryosectioning each standard was prepared and sectioned individually, whereas using bio-printing it was possible to have up to six different standards printed simultaneously, reducing the preparation time from approximately 2 hours to under 20 minutes (by approximately 6-fold). The bio-printed calibration standards were found stable for a period of two months when stored at ambient temperature and in the dark.