Effect of gold nanoparticles on transmittance and conductance of graphene oxide thin films and efficiency of perovskite solar cells

Functionalized Gold Nanoparticles for Facile Pattern-Controlled Surface Coatings

Gold nanoparticles (AuNPs) have been widely investigated as surface modifiers; nevertheless, most methods still require the pretreatment of surfaces and several steps to control coating efficiency and patterns for improved functionality. We developed functionalized AuNPs through borate-protected dopamine (B-AuNPs). The simple activation of B-AuNPs with a strong acid to remove the protected borate groups produces adhesive dopamine AuNPs (D-AuNPs). D-AuNP-coated surfaces with varied but controlled features and properties such as coating density and surface pattern were achieved using D-AuNPs with a precisely controlled dopamine density and coating conditions. Such adhesive and easily manipulated AuNPs provide a facile and time-saving technology to achieve sophisticated surface coatings using AuNPs.

Dynamic light scattering and zeta-potential as a tool for understanding the mechanism of pesticides binding toward individual components of transition metal nanoparticles and graphene oxide hybrids

Pesticides present in their commercial formulations are studied for their preferable binding toward carbon-based graphene oxide (GO) or transition metal nanoparticles (Fe, Co, Ni, and Cu), present as hybrids. This simple study also reveals the mechanism of interaction of few selected different classes of pesticides, namely, λ-cyhalothrin, imidacloprid, and metsulfuron-methyl toward these hybrids. Individually, to study this comparative binding when hybrids are not used, the understanding of preferred binding toward any of these selected compounds could be challenging, costly, and time-consuming. Dynamic light scattering (DLS) is used to study the changes observed for hydrodynamic radius and zeta potential for the stability of the resulting products. This simple method can also be extended to identify the binding mechanism for other diverse set of combinations. These studies are supported by binding of GO with nanoparticles in batch adsorption and the best fit using Langmuir and Freundlich isotherms is presented. Moreover, pesticide adsorption toward GO-nanoparticle composites is also evidenced.

Graphene oxide and its derivatives as promising In-vitro bio-imaging platforms

Intrinsic fluorescence and versatile optical properties of Graphene Oxide (GO) in visible and near-infrared range introduce this nanomaterial as a promising candidate for numerous clinical applications for early-diagnose of diseases. Despite recent progresses in the impact of major features of GO on the photoluminescence properties of GO, their modifications have not yet systematically understood. Here, to study the modification effects on the fluorescence behavior, poly ethylene glycol (PEG) polymer, metal nanoparticles (Au and Fe3O4) and folic acid (FA) molecules were used to functionalize the GO surface. The fluorescence performances in different environments (water, DMEM cell media and phosphate buffer with two different pH values) were assessed through fluorescence spectroscopy and fluorescent microscopy, while Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) and Scanning electron microscopy (SEM) were utilized to evaluate the modifications of chemical structures. The modification of GO with desired molecules improved the photoluminescence property. The synthesized platforms of GO-PEG, GO-PEG-Au, GO-PEG-Fe3O4 and GO-PEG-FA illustrated emissions in three main fluorescence regions (blue, green and red), suitable for tracing and bio-imaging purposes. Considering MTT results, these platforms potentially positioned themselves as non-invasive optical sensors for the diagnosis alternatives of traditional imaging agents.