Fluorocarbon Plasma Gas Passivation Enhances Performance of Porous Silicon for Desorption/Ionization Mass Spectrometry.

Desorption/ionization on porous silicon mass spectrometry (DIOS-MS) is shown to be a powerful technique for the sensing of low-molecular-weight compounds, including drugs and their metabolites. Surface modification of DIOS surfaces is required to increase analytical performance and ensure stability. However, common wet chemical modification techniques use fluorosilanes, which are less suitable for high-throughput manufacturing and analytical repeatability. Here, we report an alternative, rapid functionalization technique for DIOS surfaces using plasma polymerization (ppDIOS). We demonstrate the detection of drugs, metabolites, pesticides, and doping agents, directly from biological matrices, with molecular confirmation performed using the fragmentation capabilities of a tandem MS instrument. Furthermore, the ppDIOS surfaces were found to be stable over a 162 day period with no loss of reproducibility and sensitivity. This alternative functionalization technique is cost-effective and amenable to upscaling, ensuring avenues for the high-throughput manufacture and detection of hundreds of analytes across various applications while still maintaining the gold-standard clinical technique using mass spectrometry.

Rapid Detection of Anabolic and Narcotic Doping Agents in Saliva and Urine By Means of Nanostructured Silicon SALDI Mass Spectrometry.

Novel doping agents and doping strategies are continually entering the market, placing a burden on analytical methods to detect, adapt, and respond to subtle changes in the composition of biological samples. Therefore, there is a growing interest in rapid, adaptable, and ideally confirmatory analytical methods for the fight against doping. Nanostructured silicon (nano-Si)-based surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) can effectively address this need, allowing fast and sensitive detection of prohibited compounds used in sport doping. Here, we demonstrate the detection of growth hormone peptides, anabolic-androgenic steroids, and narcotics at low concentrations directly from biological matrices. Molecular confirmation was performed using the fragmentation data of the structures, obtained with the tandem mass spectrometry capabilities of the SALDI instrument. The obtained data were in excellent agreement with those obtained using leading triple quadrupole liquid chromatography-mass spectrometry instruments. Furthermore, nano-Si SALDI-MS has the capacity for high-throughput analysis of hundreds of biological samples, providing opportunities for real-time MS analysis at sporting events.

Exposure to Mn/Zn ethylene-bis-dithiocarbamate and glyphosate pesticides leads to neurodegeneration in Caenorhabditis elegans.

Epidemiological evidence suggests positive correlations between pesticide usage and the incidence of Parkinson's disease (PD). To further explore this relationship, we used wild type (N2) Caenorhabditis elegans (C. elegans) to test the following hypothesis: Exposure to a glyphosate-containing herbicide (TD) and/or a manganese/zinc ethylene-bis-dithiocarbamate-containing fungicide (MZ) may lead to neurotoxicity. We exposed N2 worms to varying concentrations of TD or MZ for 30 min (acute) or 24h (chronic). To replicate agricultural usage, a third population was exposed to TD (acute) followed by MZ (acute). For acute TD exposure, the LC(50)=8.0% (r(2)=0.6890), while the chronic LC(50)=5.7% (r(2)=0.9433). Acute MZ exposure led to an LC(50)=0.22% (r(2)=0.5093), and chronic LC(50)=0.50% (r(2)=0.9733). The combined treatment for TD+MZ yielded an LC(50)=12.5% (r(2)=0.6367). Further studies in NW1229 worms, a pan-neuronally green fluorescent protein (GFP) tagged strain, indicated a statistically significant (p<0.05) and dose-dependent reduction in green pixel number in neurons of treated worms following each paradigm. This reduction of pixel number was accompanied by visual neurodegeneration in photomicrographs. For the dual treatment, Bliss analysis suggested synergistic interactions. Taken together, these data suggest neuronal degeneration occurs in C. elegans following treatment with environmentally relevant concentrations of TD or MZ.