Synthetic biodegradable ionomers that engulf, store, and deliver intact proteins.

Telechelic anionic and cationic biodegradable ionomers capable of loading, storing, and releasing proteins are presented. Two different ionomers have been synthesized with either anionic or cationic end groups. The reaction was done quantitatively as shown by (1)H NMR. The swelling properties of the hydrophobic poly(trimethylene carbonate) polymer are contributed to the ionic end groups that display hydrophilic properties. Depending on the molecular weight of the ionomer, and also on the ionic charge, the materials swell differently in water, from approximately 50% for M(w) = 12 000 g/mol to approximately 500% when dealing with 2000 g/mol. The high swelling led us to believe that it would be possible to load and release proteins preferably in a still active form. As models, two different proteins were chosen: hemoglobin and cytochrome c. The swelling and release study shows that both ionomers possess the capability to adsorb and later release the proteins with retained structure. Release measurements from both the swollen and dried states have been evaluated with similar results, showing that the dried state seems to release a little bit less than the swollen one. These kinds of materials should be interesting for a wide variety of applications where drug and protein release is wanted, as well as in applications such as protein separation media.

Novel adsorptive polyamine coating for enhanced capillary electrophoresis of basic proteins and peptides.

In capillary electrophoresis (CE), the anionic and hydrophobic nature of the fused-silica capillary surface has long been known to present a problem in protein and peptide analysis. The use of capillary surface coating is one of the approaches to avoid the analyte-wall interactions. In this study, a new polymer, poly-LA 313, has been synthesized, physico-chemical characterized, and applied as polyamine coating for CE separations. The coating process is highly reproducible and provides fast separations of peptides and proteins in a few minutes and with high efficiency. The physically adsorbed polymer gives rise to a durable coating in the range of pH 2-10, in the presence of organic modifiers (acetonitrile and methanol) and with complex biological samples. The efficiency of the new cationic polymer was also tested performing protein and peptide separations with capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS).

Build-up of collagen and hyaluronic acid polyelectrolyte multilayers.

We have used a novel polyelectrolyte multilayer (PEM) coating consisting of the polyelectrolytes collagen and hyaluronic acid. The build-up by the layer-by-layer deposition technique is outlined by ex situ and in situ ellipsometric measurements. When collagen was added, the thickness of the PEM was increased, and the refractive index was decreased. Corresponding but opposite effects were noted when hyaluronic acid was added. These changes are considered to be explained by a diffusion mechanism. It was also found that the PEM layers were unstable at physiological pH. However, by cross-linking using N-(3-di-methylaminopropyl)-N'-ethylcarbodiimide together with N-hydroxysuccinimide, a stable PEM layer resulted. These tissue friendly PEM layers are expected to have a great impact in the design of artificial extracellular matrixes. Also, the insertion of fluorescence labels demonstrates the potential for incorporation of other functionalities.

Quaternary ammonium substituted agarose as surface coating for capillary electrophoresis.

A novel positively charged polymer of quaternary ammonium substituted agarose (Q-agarose) has been synthesized and explored for use as a coating in capillary electrophoresis. The fast and simple coating procedure is based on a multi-site electrostatic interaction between the polycationic agarose polymer and the negatively charged fused-silica surface. By simply flushing fused-silica capillaries with hot polymer solution a positively charged, hydrophilic deactivation layer is achieved. The polymer surface provides an intermediate electroosmotic flow of reversed direction, over a range of pH 2-11, compared to unmodified fused-silica. The coating procedure was highly reproducible with an RSD of 4%, evaluated as the electroosmotic flow mobility for 30 capillaries prepared at 10 different occasions. The application of Q-agarose coated capillaries in separation science was investigated using a set of basic drugs and model proteins and peptides. Due to the intermediate electroosmotic flow generated, the resolution of basic drugs could be increased, compared to using bare fused-silica capillaries. Moreover, the coating enabled separation of proteins and peptides with efficiencies up to 300.000 plates m(-1).

Novel polyamine coating providing non-covalent deactivation and reversed electroosmotic flow of fused-silica capillaries for capillary electrophoresis.

A new polycationic coating for use in capillary electrophoresis has been developed that enables chemical modification of fused-silica capillary surfaces for analysis of compounds like basic proteins. The cationic polyamine, containing short aliphatic blocks of combined 2 and 3-carbon length, was physically adsorbed onto the negatively charged fused-silica surface through ionic interaction by flushing the capillary with a polyamine solution, followed by a self-stabilization step. The polyamine coated capillaries generated an anodal electroosmotic flow that was independent of pH in the investigated range of pH 4-8. The capillary performance was demonstrated by fast separations of basic proteins with peak efficiencies in the range of 265,000-584,000 plates.

Method for immobilization of liposomes in capillary electrophoresis by electrostatic interaction with derivatized agarose.

A novel procedure for immobilization of liposomes inside fused-silica capillaries is demonstrated. First, the inner wall of the capillaries was coated with a positively charged polymer, composed of derivatized agarose. Subsequently, negatively charged liposomes were immobilized by electrostatic interaction on the polymer coating. The developed liposome coated capillaries were used as a nanoseparation tool for studying interactions between small drug compounds and liposomes. Part of this work was presented at the 15th International Symposium on Microscale Separations and Analysis, HPCE 2002, Stockholm, Sweden, April 2002.