In this oral contribution three lucky cases, where some common and inexpensive inorganic nanomaterials are involved with applications of main topics of this colloquium, will be discussed.
1. In the first case we sensitized TiO2 electrodes with QDs obtained by the SILAR technique, starting from aqueous solutions of Bi(NO3)3 as the cation precursor and Na2S as the sulfide source. In a second variant, we used a similar procedure, but the Na2S solution was replaced by elemental sulfur vapor as precursor. We found that an immersion time of 30 min leads to an efficient QDs deposition into the TiO2 porosities closer to the substrate. It was found that the presence of sodium ions in the reaction system does not directly lead to the formation of Bi2S3 on the porous TiO2 layer. Additionally, the l g l w ph l Th − l g (J−V) characteristic and the photocurrent time stability revealed: (i) the much better performance of Bi2S3 QDs sensitized photoelectrodes obtained using elemental sulfur vapor as precursor and (ii) the inconvenience of sodium ions inclusion in the attempted synthesis procedure [1].
2. A straightforward, environmental friendly and economical one-step degradation method of methyl-parathion (MP) -- a common, persistent, neurotoxic, organophosphorus pesticide -- was achieved through an aqueous suspension of copper (I) oxide nanoparticles (NPs). This type of contaminated rinse waters come from fruits previously sprayed with this bug killer. 1H nuclear magnetic resonance (NMR) results show that the hydrolysis of MP leads to the formation of 4-nitrophenol as the most common reaction product and the P=S of the MP becomes P=O, confirmed by 31P NMR. UV-visible spectra suggest the reaction follows a pseudo first-order kinetic procedure. MP degradation was established to be occurring because of the basicity properties of Cu2O NPs which increase with decreasing particle size. Our results support the potential application for the treatment of water contaminated with organophosphate pesticides [2].
3. The objective of this investigation was to evaluate the fungicidal activity of Bi2O3 nanoparticles against Candida albicans, and their antibiofilm capabilities. Our results show that aqueous colloidal bismuth oxide nanoparticles display antimicrobial activity against C. albicans growth and a complete inhibition of biofilm formation. These results are better than those obtained with the most effective oral antiseptic and commercial antifungal agents. These outcomes suggest that bismuth oxide colloidal nanoparticles could be a very interesting candidate as a fungicidal agent to be incorporated into an oral antiseptic [3].
[1] Zumeta-Dubé, I. et al (2 ) J h h m 8 9 −
[2] Rizo-Estrada J. et al. One-step Degradation of Methyl Parathion using Cu2O Nanoparticles. Under preparation
[3] Hernández-Delgadillo, R., et al. International Journal of Nanomedicine, (2013), 8 1645–1652.
