Spatially resolved endogenous improved metabolite detection in human osteoarthritis cartilage by matrix assisted laser desorption ionization mass spectrometry imaging.

Osteoarthritis (OA) is one of the most common musculoskeletal diseases, characterized by the progressive deterioration of articular cartilage. Although the disease has been well studied in the past few years, the endogenous metabolic composition and more importantly the spatial information of these molecules in cartilage is still poorly understood. Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) has been previously used for the investigation of the bimolecular distribution of proteins and lipids through the in situ analysis of cartilage tissue sections. MALDI-MSI as a tool to detect metabolites remains challenging, as these species have low abundance and degrade rapidly. In this work, we present a complete methodology, from sample preparation to data analysis for the detection of endogenous metabolites on cartilage by MSI. Our results demonstrate for the first time the ability to detect small molecules in fragile, challenging tissues through an optimized protocol, and render MSI as a tool towards a better understanding of OA.

Liquid-liquid extraction of fermentation inhibiting compounds in lignocellulose hydrolysate.

Several compounds that are formed or released during hydrolysis of lignocellulosic biomass inhibit the fermentation of the hydrolysate. The use of a liquid extractive agent is suggested as a method for removal of these fermentation inhibitors. The method can be applied before or during the fermentation. For a series of alkanes and alcohols, partition coefficients were measured at low concentrations of the inhibiting compounds furfural, hydroxymethyl furfural, vanillin, syringaldehyde, coniferyl aldehyde, acetic acid, as well as for ethanol as the fermentation product. Carbon dioxide production was measured during fermentation in the presence of each organic solvent to indicate its biocompatibility. The feasibility of extractive fermentation of hydrolysate was investigated by ethanolic glucose fermentation in synthetic medium containing several concentrations of furfural and vanillin and in the presence of decanol, oleyl alcohol and oleic acid. Volumetric ethanol productivity with 6 g/L vanillin in the medium increased twofold with 30% volume oleyl alcohol. Decanol showed interesting extractive properties for most fermentation inhibiting compounds, but it is not suitable for in situ application due to its poor biocompatibility.