Protein entrapment

Using a solution of water-containing reversed micelles of di(2-ethylhexyl)phospho-rothioic acid in isooctane, hemoglobin was extracted and concentrated. Desolubilization of the protein entrapped in the reversed micelles by weak alkahne solution was realized by adding small amounts of n-octanol [167]. 

Brook, M.A., Chen, Y., Guo, K., Zhang, Z., Jin, W., Deisingh, A., Cruz-Aguado, J. and Brennan, J.D. (2004) Proteins entrapped in silica monoliths prepared from glyceroxysilanes. Journal of Sol-Gel Science and Technology, 31,343-348. 

Construction of the optode for urea biosensor requires immobilisation of protein (and pH indicator) in the host matrix. There are several methods enabling protein entrapment. One can use gels, polymers, saccharose, various meshes and membranes78. 

L. Zheng and J.D. Brennan, Measurement of intrinsic fluorescence to probe the conformational flexibility and thermodynamic stability of a single tryptophan protein entrapped in a sol-gel derived glass matrix. Analyst 123, 1735-1744 (1998). 

Arthursson P, Edman P, Sjoholm I (1985) Biodegradable microspheres II immune response to a heterologous and an autologous protein entrapped in polyacryl starch microparticles. J Pharmacol Exp Ther 255-260. 

Up to 500 pg of plasmid DNA (for the amount of PC shown above) is dissolved in 2mL distilled water, or lOmM sodium phosphate buffer (PB) of pH 7.2 if needed. For liposomes containing both the plasmid DNA and the vaccine protein it encodes (or only the protein), up to 1 mg of the protein is included. The nature of buffer with respect to composition, pH, and molarity can be varied as long as this does not interfere with liposome formation or DNA and protein entrapment yield. Amounts of added DNA and protein can be increased proportionally to the total amount of lipid used. For cationic liposomes, the amount of added DNA can also be increased by employing more cationic lipid. 

DNA and/or protein vaccine entrapment in DRV liposomes is monitored by measuring the vaccine in the suspended pellet and combined supernatants. The most convenient way to monitor DNA entrapment is by using radio-labelled or DNA. For protein entrapment, the use of I-labelled protein tracer is recommended. If a radiolabel is not available or cannot be used, appropriate quantitative techniques should be employed. To determine DNA or protein by such techniques, a sample of the liposome suspension is mixed with Triton X-100 (up to 5% final concentration) or, preferably, with isopropanol (1 1 volume ratio) so as to liberate the entrapped materials. However, if Triton X-100 or the solubilized liposomal lipids interfere with the assay of the materials, liposomal lipids or the DNA must be extracted using appropriate techniques (6). Entrapment values for protein and DNA, whether alone or coentrapped, range between about 20% to 80% (protein) and 30%i to 100%i (DNA) of the initial material depending on the DNA or protein used and, in the case of DNA, the presence or absence of cationic charge. Values are highest for DNA when it is entrapped into cationic DRV (typical values in Table 1). 

Wang, S.F., Chen, T., Zhang, Z.L., Pang, D.W., and Wong, K.Y., Effects of hydrophobic room-temperature ionic liquid l-butyl-3-methylimidazolium tetrafluoroborate on direct electrochemistry and biocatalysis of heme proteins entrapped in agarose hydrogel films, Electrochem. Commun., 9, 1709-1714, 2007. 

Dave BC, Dunn B, Valentine JS, Zinc JI (1998) Sol-gel matrices for protein entrapment. In Immobilized biomolecules in analysis. A practical approach. Oxford University Press, Oxford... 

Sharif, S., and O Hagan, D.T. (1995), A comparison of alternative methods for determination of the levels of proteins entrapped in poly(lactide-coglycolide) microparticles, Int. J. Pharm., 115, 259-263. 

Figure 8.30 Scanning electron micrographs of bovine serum albumin-loaded microspheres prepared from a ternary blend of poly( -caprolactone). Protein entrapment efficiency and mean particle size were 28.6% and 2.9 m respectively.

Brennan, J. D., Using intrinsic fluorescence to investigate proteins entrapped in sol-gel derived materials. Applied Spectroscopy 1999, 53(3), 106A-121A... 

Wang S-F, Chen T, Zhang Z-L et al (2005) Direct electrochemistry and electrocatalysis of heme proteins entrapped in agarose hydrogel films in room temperature ionic liquids. Langmuir 21 9260-9266... 

Hermansson, J. Grahn, A. Determination of drugs by direct injection of plasma into a biocompatible extraction column based on a protein-entrapped hydrophobic phase. J.Chromatogr.A, 1994, 660, 119-129... 

Dave, B. Dunn, B. Valentine, J. Zink, J. Sol-Gel Matrix for Protein Entrapment in Immobilized Biomolecules in Analysis, T. Cass and F.S. Ligler, Eds.,... 

Moore A, McGuirk P, Adams S, Jones WC, McGee JP, O Hagan DT et al. Immunization with a soluble recombinant HIV protein entrapped in biodegradable microparticles induces HIV-specific CD8+ cytotoxic T lymphocytes and CD4+ Thl cells. Vaccine. December 1995 13(18) 1741-1749. PubMed PMID 8701587. 

Some more interesting papers on protein entrap-ments for various oral and other intakes can be found in the literature (72—74). 

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