Plasmonic and Photothermal Effects of CuS Nanoparticles Biosynthesized from Acid Mine Drainage with Potential Drug Delivery Applications.

In this work, the plasmonic and photothermal effects of CuS nanoparticles biosynthesized from acid mine drainage (AMD) were studied. CuS were formed by delivering the H2S generated by a sulfidogenic bioreactor to an off-line system containing the AMD. The precipitates collected after contact for an hour were washed and physico-chemically characterized, showing a nanoparticle with a mean diameter of 33 nm, crystalline nature and semiconductor behavior with a direct band gap of 2.2 eV. Moreover, the CuS nanoparticles exhibited localized surface plasmonic resonance in the near infrared range, with a high absorption band centered at 973 nm of wavelength, which allowed an increase in the temperature of the surrounding media under irradiation. Finally, the cytotoxicity of the CuS nanoparticles as well as their potential use as part of drug delivery platforms were investigated.

Bio-recovery of CuS nanoparticles from the treatment of acid mine drainage with potential photocatalytic and antibacterial applications.

In the present work, CuS nanoparticles were biorecovered from a real acid mine drainage (AMD) and its photocatalytic and antibacterial activities were studied. CuS were formed by delivering biogenic H2S produced by a continuous sulfidogenic bioreactor to an off-line vessel containing the AMD. The main physico-chemical properties of CuS nanoparticles were analyzed by UV-vis spectroscopy, TEM, FE-SEM, XRD and XPS. Moreover, its photocatalytic activity on the photodegradation of organic dyes in water and its antibacterial activity against several bacterial strains were studied and compared with CuS nanoparticles synthetized from a CuSO4 aqueous solution based on the same synthesis method. CuS nanoparticles from the real AMD showed similar physico-chemical properties and photocatalytic and antibacterial activities in comparison to CuS nanoparticles formed with the copper solutions. These results open the way to recover valorous CuS nanoparticles from AMD with potential industrial applications using a metal bioremediation process based on sulfidogenic bioreactors.

Sulfidogenic Bioreactor-Mediated Formation of ZnS Nanoparticles with Antimicrobial and Photocatalytic Activity.

The use of sulfidogenic bioreactors is a biotechnology trend to recover valuable metals such as copper and zinc as sulfide biominerals from mine-impacted waters. In the present work, ZnS nanoparticles were produced using "green" H2S gas generated by a sulfidogenic bioreactor. ZnS nanoparticles were physico-chemically characterized by UV-vis and fluorescence spectroscopy, TEM, XRD and XPS. The experimental results showed spherical-like shape nanoparticles with principal zinc-blende crystalline structure, a semiconductor character with an optical band gap around 3.73 eV, and fluorescence emission in the UV-visible range. In addition, the photocatalytic activity on the degradation of organic dyes in water, as well as bactericidal properties against several bacterial strains, were studied. ZnS nanoparticles were able to degrade methylene blue and rhodamine in water under UV radiation, and also showed high antibacterial activity against different bacterial strains including Escherichia coli and Staphylococcus aureus. The results open the way to obtain valorous ZnS nanoparticles from the use of dissimilatory reduction of sulfate using a sulfidogenic bioreactor.

Assessing the effectiveness of green synthetized silver nanoparticles with Cryptocarya alba extracts for remotion of the organic pollutant methylene blue dye.

In the present work, silver nanoparticles (AgNPs) synthetized with Cryptocarya alba (Peumo) leaf extract were studied. The fabrication method was fast, low cost, and eco-friendly, and the final properties of AgNPs were determined by experimental parameters, such as AgNO3 and Peumo extract concentrations used. Setting suitable experimental conditions, crystalline AgNPs with apparent spherical forms and average diameter around 3.5 nm were obtained. In addition, the capability of synthesized Peumo-AgNPs to remove methylene blue dye (MB) in aqueous solution as well as their catalytic effectiveness was also investigated. The results showed that green synthesized AgNPs can remove fast and effectively the MB dye from aqueous medium by itself, but better results were found acting like catalyst by using sodium borohydride (NaBH4) in the reaction. In addition, this green nanomaterial can be recycling several times maintaining initial properties for removal of MB. Thus, AgNPs synthetized with Peumo leaf extracts could be an excellent catalyst candidate for degradation of blue methylene dye in chemical industries.

Formation of antireflection Zn/ZnO core-shell nano-pyramidal arrays by O2+ ion bombardment of Zn surfaces.

ZnO is probably one of the most studied oxides since ZnO nanostructures are a very rich family of nanomaterials with a broad variety of technological applications. Although several chemical techniques offer the possibility to obtain such ZnO nanostructures, here we show that the controlled modification of the zinc surface by low-energy O2+ bombardment leads to the formation of core-shell Zn/ZnO nano-pyramidal arrays that suppress the reflection of light decreasing the reflectivity below 6% in the wavelength range of 300-900 nm. This controlled and scalable protocol opens the door to a broad range of possibilities for the use of ion bombardment to produce surface modifications for technological applications in the field of photoelectric devices and solar cells.