The very first stages of the incorporation of tetraethoxysilane (TEOS) into aqueous tetrapropylammonium hydroxide (TPAOH) by hydrolysis are investigated to clarify the formation of silicate species in solution: oligomers and nanoparticles. Silicate speciation of both oligomers and nanoparticles were characterized using quantitative 29Si NMR, electrospray ionization mass spectrometry (ESI-MS), dynamic light scattering (DLS), and 1H diffusion-ordered NMR spectroscopy (DOSY). The main parameter measured for following this formation with the advancement of hydrolysis of TEOS is the evolution of silicon connectivity, in oligomers as well as in nanoparticles. At the beginning of TEOS hydrolysis, small oligomers are formed, which grow in number and size as the reaction progresses, with an average connectivity going from 0 to 2.1. At Si/TPAOH ratio of 1.0 and above, nanoparticles form through aggregation of oligomers with some additional condensation. Their connectivity varies from 2.4 to 3.1. These nanoparticles cannot be confused with condensed silica particles.

If proteome datasets are to be collated, shared, and merged for higher level proteome analyses, there is a need for generally accepted strategies and reagents for optimization and standardization of instrument performance. At present, there is no single protein or peptide standard set that is capable of assessing instrument performance for peptide separation and analysis in this manner. To create such a standard, we have used the recently described QconCAT methodology to generate an artificial protein, QCAL. This protein, a concatenation of tryptic peptides that is expressed in E. coli, provides a stoichiometrically controlled mixture of peptides that are amenable to analysis by all commonly used instrumentation platforms for proteomics.

Play it again, SAM. Peptide substrates immobilised on self‐assembled monolayer (SAM)‐coated gold surfaces were efficiently glycosylated with UDP‐N‐acetyl‐α‐D‐galactosamine:polypeptide N‐acetylgalactosaminyltransferase 2 (ppGalNAcT2) to form the α‐D‐GalNAc threonine/serine linkage. Label‐free analysis of the reactions were performed by using MALDI‐ToF mass spectrometry.