Silver nanofractals (Ag-NFs) have been electrosynthesized and characterized by means of morphological and spectroscopic analytical techniques. In particular, X-ray photoelectron spectroscopy has been used to assess the nanomaterial surface chemical state. Ag-NFs show interesting perspectives in bioanalytical applications, particularly as non-conventional desorption and ionization promoters in laser desorption ionization mass spectrometry.
In the present study, gold/surfactant core/shell colloidal nanoparticles with a controlled morphology and chemical composition have been obtained via the so-called sacrificial anode technique, carried out in galvanostatic mode. As synthesized Au-NPs had an average core diameter comprised between 4 and 8 nm, as a function of the electrochemical process experimental conditions. The UVVis characterization of gold nanocolloids showed clear spectroscopic size effects, affecting both the position and width of the nanoparticle surface plasmon resonance peak.The nanomaterial surface spectroscopic characterization showed the presence of two chemical states, namely nanostructured Au (0) (its abundance being higher than 90%) and Au (I) . Au-NPs were then deposited on the top of a capacitive Field Effect sensor and subjected to a mild thermal annealing aiming at removing the excess of stabilizing surfactant molecules. Au-NP sensors were tested towards some gases found in automotive gas exhausts. The sensing device showed the largest response towards NO x , and much smaller -if any-responses towards interferent species such as NH 3 , H 2 , CO, and hydrocarbons.
The surface chemistry of gold nanowires (AuNWs) has been systematically assessed in terms of contamination and cleaning processes. The nanomaterial's surface quality was correlated to its performance in the matrix-free laser desorption ionization mass spectrometry (LDI-MS) analysis of low molecular weight analytes. Arrays of AuNWs were deposited on glass slides by means of the lithographically patterned nanowire electrodeposition technique. AuNWs were then characterized in terms of surface chemical composition and morphology using X-ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy. AuNWs were subjected to a series of well-known cleaning procedures with the aim of producing the best performing surfaces for the LDI-MS detection of leucine enkephalin, chosen as a model analyte with a molar mass below 1,000 g/mol. Prolonged cyclic voltammetry in 2 M sulfuric acid and, most of all, oxygen plasma cleaning for 5 min provided the best results in terms of simpler (interference-free) and more intense mass spectrometry spectra of the reference compound. The analyte always ionized as the sodiated adduct, and leucine enkephalin limits of detection of 0.5 and 2.5 pmol were estimated for the positive and negative analysis modes, respectively. This study points out the tight correlation existing between the chemical status of the nanostructure surface and the AuNW-assisted LDI-MS performance in terms of reproducibility of spectra, intensity of analyte ions and reduction of interferences.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.