Halloysite (Hal) has already been proposed as a support for zinc oxide nanoparticles synthesis due to the possibility of adsorbing ZnO on its internal and external tubular surface, but no attention has been devoted to evaluate the effect of this support on radiation screening capabilities. In this paper, zinc oxide nanoparticles were obtained by three different methods in the presence of Hal. Adsorption, solvent evaporation, and solvothermal methods were used. Quantitative Zn was determined by inductively coupled plasma optical emission spectrometry (ICP-OES), and nanocomposites were characterized by X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). This characterization elucidated that three different nanocomposites were obtained. In particular, when the adsorption method was used, small and quite uniform sized (10–30 nm) zinc oxide nanoparticles confined inside the Hal nanotubules were obtained. The UV–vis spectra of these nanocomposites revealed their ability to interact with a wide portion of UV–vis radiation which leads to enhanced sun screening performance.

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A solid-state Ultraviolet-photoreduction process of silver cations to produce Ag0 nanostructures on a mesoporous silica is presented as an innovative method for the preparation of efficient environmental anti-fouling agents. Mesoporous silica powder, contacted with AgNO3, is irradiated at 366 nm, where silica surface defects absorb. The detailed characterization of the materials enables us to document the silica assisted photo-reduction. The appearance of a Visible (Vis) band centered at 470 nm in the extinction spectra, due to the surface plasmon resonance of Ag0 nanostructures, and the morphology changes observed in transmission electron microscopy (TEM) images, associated with the increase of Ag/O ratio in energy dispersive X-ray (EDX) analysis, indicate the photo-induced formation of Ag0. The data demonstrate that the photo-induced reduction of silver cation occurs in the solid state and takes place through the activation of silica defects. The activation of the materials after UV-processing is then tested, evaluating their antimicrobial activity using an environmental filamentous fungus, Aspergillus niger. The treatment doubled inhibitory capacity in terms of minimal inhibitory concentration (MIC) and biofilm growth. The antimicrobial properties of silver–silica nanocomposites are investigated when dispersed in a commercial sealant; the nanocomposites show excellent dispersion in the silicon and improve its anti-fouling capacity.

Radiation up-conversion through triplet-triplet annihilation mechanism has been widely studied, mostly in solution and de-aerated conditions. We propose oil-in-silica up-converting nanocapsules resulting in a robust solid-like material able to generate...

Solar cells absorbing layers made of metal-halide perovskites (MHPs) are usually deposited from solution phase precursors, which is one of the reasons why these materials received a huge research boost...

DNA-stabilized silver nanoclusters (DNA-AgNCs) have promising properties for biosensing and bioimaging applications. However, in order to enhance the applicability in these fields, a detailed understanding of the interactions that occur between DNA-AgNCs and other biomolecules is essential. In this work, the spectroscopic properties of red-emitting DNA-AgNCs have been investigated in the presence of three biomolecules, namely lysozyme, bovine serum albumin and ss-DNA, which have been selected in order to have either a different biological nature (two proteins and one nucleic acid) or different net charge at physiological pH (one positive and two negative). The systematic characterization of the steady-state absorption and emission spectra, combined with time-resolved fluorescence and anisotropy decay measurements, of DNA-AgNCs in the presence of each biomolecule, allowed to establish the nature of the interactions that affect the photophysical properties of the DNA-AgNCs.

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Silver nanoparticles are usually prepared by the reduction of silver cations through chemical and non-sustainable procedures that involve the use of reducing chemical agents. Therefore, many efforts have been made in the search for sustainable alternative methods. Among them, an ultrasound-assisted procedure could be a suitable and sustainable method to afford well-dispersed and nanometric silver particles. This paper describes a sustainable, ultrasound-assisted method using citrate as a reducing agent to prepare silver@hydroxyapatite functionalized calcium carbonate composites. For comparison, an ultrasound-assisted reduction was performed in the presence of NaBH4. The composites obtained in the presence of these two different reducing agents were compared in terms of nanoparticle nature, antimicrobial activity, and cytotoxic activity. The nanoparticle nature was investigated by several techniques, including X-ray powder diffraction, field-emission scanning electron microscopy, transmission electron microscopy, UV–Vis spectroscopic measurements, and X-ray photoemission spectroscopy. Nanoparticles with a predominance of Ag or Ag3PO4 were obtained according to the type of reducing agent used. All composites were tested for antimicrobial and antibiofilm activities against Gram-positive and Gram-negative (Staphylococcus aureus and Pseudomonas aeruginosa, respectively) bacteria and for cytotoxicity towards human skin keratinocytes and human fibroblasts. The nature of the nanoparticles, Ag or Ag3PO4, and their predominance seemed to affect the in vitro silver release and the antimicrobial and antibiofilm activities. The composites obtained by the citrate-assisted reduction gave rise to the best results.