Protein-based materials injecting

Desirable at this point would be an implantable naltrexone delivery system that would not depend on patient compliance. It could be a biodegradable controlled release device, for example, injectable by hypodermic syringe for relatively short-term release. Alternatively, it could be implanted by trocar or by laparoscope for release for months as a biocompatible and biodegradable yet removable vehicle should patients circumstances warrant substantial pain control. As demonstrated below (see Figure 9.39), properly designed protein-based materials exhibit this potential. 

The analysis demonstrates the elegant use of a very specific type of column packing. As a result, there is no sample preparation, so after the serum has been filtered or centrifuged, which is a precautionary measure to protect the apparatus, 10 p.1 of serum is injected directly on to the column. The separation obtained is shown in figure 13. The stationary phase, as described by Supelco, was a silica based material with a polymeric surface containing dispersive areas surrounded by a polar network. Small molecules can penetrate the polar network and interact with the dispersive areas and be retained, whereas the larger molecules, such as proteins, cannot reach the interactive surface and are thus rapidly eluted from the column. The chemical nature of the material is not clear, but it can be assumed that the dispersive surface where interaction with the small molecules can take place probably contains hydrocarbon chains like a reversed phase. 

This chapter describes the rationale behind and means of construction of inexpensive, low to moderate throughput protein arrays. The method of construction is based on injection of analytes into a block of frozen optimum cutting temperature (OCT), the gel media used for frozen sections, and sectioned on a cryostat. The array section is applied to a nitrocellulose pad. Once on nitrocellulose, the array can be utihzed in any fashion desired. The analytes can be any biologic sample including peptides, proteins, antibodies, cells, nucleic acids, or any other material that can tolerate freezing. This platform provides investigators a flexible inexpensive easy-to-fashion platform to create multiplex assays both in the number of samples analyzed and in the types of assays. 

Thus, protein-based bioplastics can be obtained by extrusion, calendering, extrusion blow moulding, injection and thermoforming processes. These thermoplastic processes are derived from synthetic material production processes. 

Biodegradable plastics based on soy protein were prepared with glycerol as a plasticizer and compounded wi different additives such as polycaprolactone and zinc stearate as well as heat treated at various temperatures after the injection molding process in order to characterize base material strength and the effect of water absorption. The results indicated that the polycaprolactone and, respectively a medium to high heat treatment enhanced the tensile strength and decreased the water absorption significantly. 

These separations can be carried out using a silica-based bonded phase however, the important advantage of organic polymer stationary phase materials is their chemical stability. The columns can be washed by using an alkaline solution after a certain number of injections. According to the chromatograms, the proteins in serum are completely eluted and nothing remains inside the column. However, the pressure drop in this type of analysis... 

The bioanalyst can be required to analyse most biofluids although the most common are urine and the aqueous phase of blood, i.e. plasma or serum. Other samples may be cell and tissue extracts, synovial fluid, cerebrospinal fluid (CSF) and saliva. In the case of urine and CSF with their very low protein content it might be possible to directly inject the sample into an HPLC column. With most silica-based packing materials, direct injection of blood proteins will rapidly lead to column deterioration. HPLC columns are expensive and their efficiency is easily lost so correct preparation of samples will not only improve column life but also improve the results. At its simplest it is only necessary to remove particulate matter from samples to prevent clogging of the column and frits. Modern HPLC packings are very susceptible to contamination by proteins, fats and other macromolecules from biological samples and it is necessary to remove these (except of course for protein analysis). 

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