Graphene-based electrochemical sensor for detection of 2,4,6-trinitrotoluene (TNT) in seawater: the comparison of single-, few-, and multilayer graphene nanoribbons and graphite microparticles

The detection of explosives in seawater is of great interest. We compared response single-, few-, and multilayer graphene nanoribbons and graphite microparticle-based electrodes toward the electrochemical reduction of 2,4,6-trinitrotoluene (TNT). We optimized parameters such as accumulation time, accumulation potential, and pH. We found that few-layer graphene exhibits about 20% enhanced signal for TNT after accumulation when compared to multilayer graphene nanoribbons. However, graphite microparticle-modified electrode provides higher sensitivity, and there was no significant difference in the performance of single-, few-, and multilayer graphene nanoribbons and graphite microparticles for the electrochemical detection of TNT. We established the limit of detection of TNT in untreated seawater at 1 μg/mL

Number of graphene layers exhibiting an influence on oxidation of DNA bases : analytical parameters

This article investigates the analytical performance of double-, few- and multi-layer graphene upon oxidation of adenine and guanine. We observed that the sensitivity of differential pulse voltammetric response of guanine and adenine is significantly higher at few-layer graphene surface than single-layer graphene. We use glassy carbon electrode as substrate coated with graphenes. Our findings shall have profound influence on construction of graphene based genosensors

Oxidation of DNA bases influenced by the presence of other bases

Electrochemical detection of DNA is a highly important topic. Here we show that the electrochemical responses of one DNA base (guanine, adenine, cytosine or thymine), in terms of oxidation potential, current intensity, peak width and resolution can be highly influenced by the presence of other DNA bases at electrochemically reduced graphene oxide (ER-GO) as well as standard glassy carbon electrode. We have observed that the effects were more significant for adenine base on ER-GO and cytosine base on glassy carbon (GC) electrode. Differences in responses were generally low in a mixture of four different DNA bases but interestingly, deviations become significantly larger when only one or two other bases were present. Our findings are of paramount importance for future developments in DNA detection and analysis since individual DNA bases are not present in isolation in nature or in typical biosensing systems

A chemical route to increase hot spots on silver nanowires for surface-enhanced Raman spectroscopy application

The effective number of surface-enhanced Raman spectroscopy (SERS) active hot spots on plasmonic nanostructures is the most crucial factor in ensuring high sensitivity in SERS sensing platform. Here we demonstrate a chemical etching method to increase the surface roughness of one-dimensional Ag nanowires, targeted at creating more SERS active hot spots along Ag nanowire’s longitudinal axis for increased SERS detection sensitivity. Silver nanowires were first synthesized by the conventional polyol method and then subjected to chemical etching by NH4OH and H2O2 mixture. The surfaces of silver nanowires were anisotropically etched off to create miniature “beads on a string” features with increased surface roughness while their crystallinity was preserved. Mapping of single-nanowire SERS measurements showed that the chemical etching method has overcome the limitation of conventional one-dimensional Ag nanowires with limited SERS active area at the tips to produce etched Ag nanowires with an increase in Raman hot spots and polarization-independent SERS signals across tens of micrometers length scale

A Chemical Route To Increase Hot Spots on Silver Nanowires for Surface-Enhanced Raman Spectroscopy Application

The effective number of surface-enhanced Raman spectroscopy (SERS) active hot spots on plasmonic nanostructures is the most crucial factor in ensuring high sensitivity in SERS sensing platform. Here we demonstrate a chemical etching method to increase the surface roughness of one-dimensional Ag nanowires, targeted at creating more SERS active hot spots along Ag nanowire’s longitudinal axis for increased SERS detection sensitivity. Silver nanowires were first synthesized by the conventional polyol method and then subjected to chemical etching by NH₄OH and H₂O₂ mixture. The surfaces of silver nanowires were anisotropically etched off to create miniature “beads on a string” features with increased surface roughness while their crystallinity was preserved. Mapping of single-nanowire SERS measurements showed that the chemical etching method has overcome the limitation of conventional one-dimensional Ag nanowires with limited SERS active area at the tips to produce etched Ag nanowires with an increase in Raman hot spots and polarization-independent SERS signals across tens of micrometers length scale