Detection of phenylthiohydantoin derivatives of amino acids by SIMS

Secondary Ion Mass Spectrometry of Macromolecules Loading in Individual Polyelectrolyte Multilayer Microcapsules

The control over the amount of a payload in polyelectrolyte multilayer microcapsules is of particular importance for several applications, such as transportation and delivery of drugs, enzymes, and other (bio)active materials. In this work, secondary ion mass spectrometry is applied to measure the content of peroxidase in individual capsules. The distribution of a payload among the capsules in a batch is analyzed for different loading routines. Absorption in porous CaCO3 demonstrates lower enzyme content with a standard deviation of 40 % on average. pH-Controlled post-loading gives two to three times higher content and a standard deviation of 20–25 %. The decrease of pH upon post-loading increases the encapsulation efficiency.

A review: secondary ion mass spectrometry (SIMS) of polymeric biomaterials

This paper comprises a short review of the application of secondary ion mass spectrometry (SIMS) to the surface chemical analysis of biomaterials, with the main emphasis on biomedical polymers. By the use of appropriate examples, the technique is shown to provide detailed information on the surface chemical structure of the top 1-2 nm of a range of biodegradable polymers, copolymers, surface modified materials and drug delivery systems. Semi-quantitative information on the surface composition of copolymeric materials can also be obtained. The molecular specificity of the technique can be exploited to identify the presence of additives (eg. drugs, peptides) or contaminants in the surfaces of biomaterials. This approach can be extended to situations where biomolecules of interest are covalently immobilised on biomaterial surfaces. Finally, SIMS imaging analysis is shown to provide a means of determining the lateral distribution of additive molecules in surfaces.

Negative ion chemical ionization mass spectrometry of 2,4-dinitrophenyl amino acid esters

We report the negative ion chemical ionization mass spectra of 2,4-dinitrophenyl (DNP) amino acid methyl esters. For the common amino acids, these derivatives exhibit very simple mass spectra; the molecular anion is the base peak in all cases. The electrophilicity of the DNP group allows selective and sensitive ionization. Amino acids can be identified singly or in mixtures by their molecular weights, and picomole detection is possible. Chromatography is only needed for Leu/Ile differentiation. Amino-terminal analysis of proteins is demonstrated.