Magnetite-alginate beads for purification of some starch degrading enzymes

Multifunctional alginate microspheres for biosensing, drug delivery and magnetic resonance imaging

This research aims to develop and investigate a multifunctional implantable system capable of biosensing, drug delivery and magnetic resonance imaging (MRI) for continuous monitoring, controlled anti-inflammatory drug delivery and imaging, respectively. A glucose biosensor, diclofenac sodium (Diclo) and magnetic nanoparticles (MNP) were used as the biosensor component, anti-inflammatory agent and MRI contrast agent, respectively. MNP were synthesized by the co-precipitation technique and loaded with the sensor and drug components into alginate microspheres using a commercial droplet generator. The multifunctional system was then characterized using optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, vibrating sample magnetometry (VSM) and MRI. The MNP were found to be in the size range of 5-15 nm. The final system, comprising the biosensor, drug and MNP loaded inside alginate microspheres, was found to be in the size range of 10-60 μm. Biosensing studies indicated an excellent glucose response curve, with a regression coefficient of 0.974 (0-10mM of glucose, response time: 4 min). In vitro Diclo release shows that MNP loading in alginate microspheres increases the burst release percentage by 11-12% in both 60 and 10 μm particles. However, the duration of release for 85% drug release decreases with MNP loading by 7 and 6 days for 39 the 60 and 10 μm particles, respectively. Super-paramagnetism was confirmed by VSM, with 2.09 and 1.368 emu g(-1), respectively, for the 60 and 10 μm particles, with no hysteresis. MRI showed significant contrast for both sizes. The particles showed an excellent biocompatibility (>80%) for all combinations of formulations. The system shows a great potential for biosensing with concurrent drug delivery and visualization for biomedical applications.

A biotechnological perspective on the application of iron oxide magnetic colloids modified with polysaccharides

Iron oxide magnetic nanoparticles (MNPs) alone are suitable for a broad spectrum of applications, but the low stability and heterogeneous size distribution in aqueous medium represent major setbacks. These setbacks can however be reduced or diminished through the coating of MNPs with various polymers, especially biopolymers such as polysaccharides. Polysaccharides are biocompatible, non-toxic and renewable; in addition, they possess chemical groups that permit further functionalization of the MNPs. Multifunctional entities can be created through decoration with specific molecules e.g. proteins, peptides, drugs, antibodies, biomimetic ligands, transfection agents, cells, and other ligands. This development opens a whole range of applications for iron oxide nanoparticles. In this review the properties of magnetic structures composed of MNPs and several polysaccharides (Agarose, Alginate, Carrageenan, Chitosan, Dextran, Heparin, Gum Arabic, Pullulan and Starch) will be discussed, in view of their recent and future biomedical and biotechnological applications.

Applications of Alginate in Bioseparation of Proteins

Alginate is a polysaccharide that is a block polymer consisting of block units of guluronic acid and mannuronic acid. It shows inherent biological affinity for a variety of enzymes such as pectinase, lipase, phospholipase D, a and ss amylases and glucoamylase. Taking advantage of its precipitation with Ca2+ and the above-mentioned property, alginate has been used for purification of these enzymes by affinity precipitation, aqueous two phase separation, macroaffinity ligand facilitated three phase partitioning, immobilized metal affinity chromatography and expanded bed affinity chromatography. Thus, this versatile marine resource has tremendous potential in bioseparation of proteins.

Magnetic techniques for the isolation and purification of proteins and peptides

Isolation and separation of specific molecules is used in almost all areas of biosciences and biotechnology. Diverse procedures can be used to achieve this goal. Recently, increased attention has been paid to the development and application of magnetic separation techniques, which employ small magnetic particles. The purpose of this review paper is to summarize various methodologies, strategies and materials which can be used for the isolation and purification of target proteins and peptides with the help of magnetic field. An extensive list of realised purification procedures documents the efficiency of magnetic separation techniques.

Magnetic alginate microparticles for purification of $alpha;-amylases

Spherical magnetic alginate microparticles (25-60 microm in diameter) were prepared using the microemulsion system, with water-saturated 1-pentanol as the organic phase. The limited solubility of 1-pentanol in water enabled simple removal of the organic solvent from the prepared beads with water solution. The prepared alginate microparticles were used as magnetic affinity adsorbents for specific purification of alpha-amylases. Enzyme activity was eluted by 1.0 M maltose. alpha-Amylases from Bacillus amyloliquefaciens and porcine pancreatic acetone powder were purified 9- and 12-fold with 88 and 96% activity recovery, respectively.

Macroaffinity ligand-facilitated three-phase partitioning for purification of glucoamylase and pullulanase using alginate

Starch-degrading enzymes glucoamylase (from Aspergillus niger), and pullulanase (from Bacillus acidopullulyticus) were purified using alginates (polysaccharides consisting of mannuronic acids and guluronic acids) by a recently developed technique called macroaffinity ligand-facilitated three-phase partitioning (MLFTPP). In this process, a crude preparation of the enzyme was mixed with alginate. On addition of appropriate amounts of ammonium sulfate and t-butanol, the alginate bound enzyme appeared as an interfacial precipitate between the lower aqueous and the upper t-butanol phase. Enzyme activity from this interfacial precipitate was recovered using 1M maltose. Glucoamylase and pullulanase were purified 20- and 38-fold with 83% and 89% activity recovery, respectively. Both the purified preparations showed a single band on SDS-PAGE.