Evaporation and deposition of alkyl-capped silicon nanocrystals in ultrahigh vacuum.

Nanocrystals are under active investigation because of their interesting size-dependent properties and potential applications. Silicon nanocrystals have been studied for possible uses in optoelectronics, and may be relevant to the understanding of natural processes such as lightning strikes. Gas-phase methods can be used to prepare nanocrystals, and mass spectrometric techniques have been used to analyse Au and CdSe clusters.

Silicon nanoparticles: applications in cell biology and medicine.

In this review, we describe the synthesis, physical properties, surface functionalization, and biological applications of silicon nanoparticles (also known as quantum dots). We compare them against current technologies, such as fluorescent organic dyes and heavy metal chalcogenide-based quantum dots. In particular, we examine the many different methods that can be used to both create and modify these nanoparticles and the advantages they may have over current technologies that have stimulated research into designing silicon nanoparticles for in vitro and in vivo applications.

A rapid and direct method for the determination of active site accessibility in proteins based on ESI-MS and active site titrations.

We have developed an electrospray ionisation mass spectrometry (ESI-MS) technique that can be applied to rapidly determine the number of intact active sites in proteins. The methodology relies on inhibiting the protein with an active-site irreversible inhibitor and then using ESI-MS to determine the extent of inhibition. We have applied this methodology to a test system: a serine protease, subtilisin Carlsberg, and monitored the extent of inhibition by phenylmethylsulfonyl fluoride (PMSF), an irreversible serine hydrolase inhibitor as a function of the changes in immobilisation and hydration conditions.