Operando monitoring of a room temperature nanocomposite methanol sensor

Highly Stable Self-Cleaning Paints Based on Waste-Valorized PNC-Doped TiO2 Nanoparticles

Adding photocatalytically active TiO2 nanoparticles (NPs) to polymeric paints is a feasible route toward self-cleaning coatings. While paint modification by TiO2-NPs may improve photoactivity, it may also cause polymer degradation and release of toxic volatile organic compounds. To counterbalance adverse effects, a synthesis method for nonmetal (P, N, and C)-doped TiO2-NPs is introduced, based purely on waste valorization. PNC-doped TiO2-NP characterization by vibrational and photoelectron spectroscopy, electron microscopy, diffraction, and thermal analysis suggests that TiO2-NPs were modified with phosphate (P=O), imine species (R=N-R), and carbon, which also hindered the anatase/rutile phase transformation, even upon 700 °C calcination. When added to water-based paints, PNC-doped TiO2-NPs achieved 96% removal of surface-adsorbed pollutants under natural sunlight or UV, paralleled by stability of the paint formulation, as confirmed by micro-Fourier transform infrared (FTIR) surface analysis. The origin of the photoinduced self-cleaning properties was rationalized by three-dimensional (3D) and synchronous photoluminescence spectroscopy, indicating that the dopants led to 7.3 times stronger inhibition of photoinduced e-/h+ recombination when compared to a benchmark P25 photocatalyst.

Microalgae-derived Co3O4 nanomaterials for catalytic CO oxidation

Efficient carbon monoxide oxidation is important to reduce its impacts on both human health and the environment. Following a sustainable synthesis route toward new catalysts, nanosized Co3O4 was synthesized based on extracts of microalgae: Spirulina platensis, Chlorella vulgaris, and Haematococcus pluvialis. Using the metabolites in the extract and applying different calcination temperatures (450, 650, 800 °C) led to Co3O4 catalysts with distinctly different properties. The obtained Co3O4 nanomaterials exhibited octahedral, nanosheet, and spherical morphologies with structural defects and surface segregation of phosphorous and potassium, originating from the extracts. The presence of P and K in the oxide nanostructures significantly improved their catalytic CO oxidation activity. When normalized by the specific surface area, the microalgae-derived catalysts exceeded a commercial benchmark catalyst. In situ studies revealed differences in oxygen mobility and carbonate formation during the reaction. The obtained insights may facilitate the development of new synthesis strategies for manufacturing highly active Co3O4 nanocatalysts.

A novel facile synthesis of metal nitride@metal oxide (BN/Gd2O3) nanocomposite and their antibacterial and anticancer activities

In this study, a novel core/shell nanocomposite structure (h-BN@Gd2O3 NCs) was created for the first time by combining hexagonal boron nitride (h-BN) with doped gadolinium oxide (Gd2O3) using different laser pulse numbers, i.e., 150, 338, and 772 pulses. We employed various analytical techniques, including mapping analysis, FE-SEM, EDS, HRTEM, SAED, XRD, zeta potential analysis, DLS, FTIR, Raman spectroscopy, and PL measurements, to characterize the synthesized h-BN, c-Gd2O3, and h-BN@Gd2O3 NCs (338 pulses). XRD results indicated hexagonal and cubic crystal structures for BN and Gd2O3, respectively, while EDS confirmed their chemical composition and elemental mapping. Chemical bonds between B-N-Gd, B-N-O, and Gd-O bands at 412, 455, 474, and 520 cm-1 were identified by FTIR analysis. The antimicrobial and anticancer activities of these NCs using agar well diffusion and MTT assays. They exhibited potent antibacterial properties against both Gram-positive and Gram-negative pathogens. Furthermore, NCs have reduced the proliferation of cancerous cells, i.e., human colon adenocarcinoma cells (HT-29) and human breast cancer cells (MCF-7), while not affecting the proliferation of the normal breast cell line (MCF-10). The anticancer efficacy of NCs was validated by the AO/EtBr assay, which confirmed apoptotic cell death. Blood compatibility on human erythrocytes was also confirmed by hemolytic and in vitro toxicity assessments. The compiled results of the study proposed these nanoparticles could be used as a promising drug delivery system and potentially in healthcare applications.

Biosynthesis of Copper Oxide and Silver Nanoparticles by Bacillus Spores and Evaluation of the Feasibility of Their Use in Antimicrobial Paints

Modification of paint with nanoparticles (NPs) provides self-cleaning, water/dirt-repellent, and other properties. Therefore, the aim of the present study was to biosynthesize silver (Ag) and copper oxide (CuO) NPs and to prepare NP-modified paint. To this end, AgNPs and CuONPs were biosynthesized using Bacillus atrophaeus spores and commercial and crude dipicolinic acid (DPA) extracted from the spore of this bacterium. The synthesized NPs were characterized using electron microscopy, Fourier-transform infrared (FTIR), X-ray diffraction analysis (XRD), and energy-dispersive X-ray spectroscopy (EDS) methods. A minimum inhibitory concentration (MIC) assay of NPs against Escherichia coli ATCC8739 and Staphylococcus aureus ATCC6538 was carried out. The antibacterial effects of prepared NP-paint complexes were assessed using an optical density (OD) comparison before and after adding metal sheets coated with NP-paint complexes into the nutrient broth medium. Four different types of NPs were synthesized in this research: AgNPs synthesized by spore (A), AgNPs synthesized by commercial DPA (B), AgNPs synthesized by crude DPA (C), and CuONPs synthesized by spore (D). SEM analysis confirmed the spherical shape of NPs. According to the results, NPs A, B, and D showed higher antibacterial activity against S. aureus compared to E. coli. Furthermore, the analysis of the antibacterial effects of NP-paint complexes suggested that paint-NPs A, B, and C displayed higher activity on E. coli compared to S. aureus. Moreover, the antibacterial effect of paint-NP D was significantly lower than other NPs. According to this robust antibacterial effect on pathogenic bacteria, it seems that these NP-paint complexes could be useful in public places such as hospitals, airports, dormitories, schools, and office buildings, where the rate of transmission of infection is high.

Green Synthesis, Characterization, and Antiparasitic Effects of Gold Nanoparticles against Echinococcus granulosus Protoscoleces

Echinococcosis, or hydatidosis, is one of the most important zoonotic diseases, which is initiated by the larval stage in the clasts of Echinococcus granulosus. For the treatment of hydatidosis, surgery is still the preferred method and the first line of treatment for symptomatic patients. Unfortunately, most of the scolicidal agents that are injected inside cysts during hydatid cyst surgery have side effects, including leaking out of the cyst and adverse effects on the living tissue of the host, such as necrosis of liver cells, which limits their use. This work was carried out to study the lethal effect of green synthesized gold nanoparticles (Au-NCs) against hydatid cyst protoscoleces. Au-NCs were green synthesized using the Saturja khuzestanica extract. Au-NCs were characterized by UV-visible absorbance assay, electron microscopy analysis, X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. Scolicidal properties of Au-NCs (1-5 mg/mL) were studied against protoscoleces for 10-60 min. The effect of Au-NCs on the expression level of the caspase-3 gene as well as the ultrastructural examination was studied by real-time PCR and scanning electron microscopy (SEM). The cytotoxicity of Au-NCs on hepatocellular carcinoma (HepG₂) and normal embryonic kidney (HEK293) cell lines was also studied by the cell viability assay. The obtained Au-NCs are cubes and have an average size of 20-30 nm. The highest scolicidal efficacy was observed at 5 mg/mL with 100% mortality after 20 min of treatment for hydatid cyst protoscoleces. In ex vivo, Au-NCs required more incubation time, indicating more protoscolicidal effects. Au-NCs markedly upregulated the gene level of caspase-3 in protoscoleces; whereas they changed the ultra-structure of protoscoleces by weakening and disintegrating the cell wall, wrinkles, and protrusions due to the formation of blebs. We showed the effective in vitro and ex vivo scolicidal effects of Au-NCs against hydatid cyst protoscoleces by provoking the apoptosis process of caspase-3 activation and changing the ultrastructure of protoscoleces with no significant cytotoxicity against human normal cells. However, additional studies should be conducted to determine the possible harmful side effects and accurate efficacy.

Nanoparticles from Microalgae and Their Biomedical Applications

Over the years, microalgae have been a source of useful compounds mainly used as food and dietary supplements. Recently, microalgae have been used as a source of metabolites that can participate in the synthesis of several nanoparticles through inexpensive and environmentally friendly routes alternative to chemical synthesis. Notably, the occurrence of global health threats focused attention on the microalgae application in the medicinal field. In this review, we report the influence of secondary metabolites from marine and freshwater microalgae and cyanobacteria on the synthesis of nanoparticles that were applied as therapeutics. In addition, the use of isolated compounds on the surface of nanoparticles to combat diseases has also been addressed. Although studies have proven the beneficial effect of high-value bioproducts on microalgae and their potential in medicine, there is still room for understanding their exact role in the human body and translating lab-based research into clinical trials.