water from processing of turnip greens, green beans, and corn showed significant reductions in color plus turbidity, COD, total P, and suspended solids [159].
Casein hydrolysis in stirred tank reactors using chymotrypsin immobilized on
magnetic supports was studied. A comparison was made of the kinetics in batch
and continuous stirred tank reactors [160]. Two types of commercially available
magnetic separation devices were tested for use in catalyst recovery. HGMS enabled paramagnetic particles to be removed from a rapidly flowing liquid. The
filamentary matrix materials used (steel wool or expanded metal lath) provided
a large volume for trapping magnetic particles. In this way, Ni particles (3–7 mm
in diameter) can easily be separated from an aqueous suspension.
The ability of immobilized lectin-magnetic separation to improve methods
for the detection of Staphylococcus aureus, Salmonella enteritidis and Listeria
monocytogenes was reported [161]. A new assay, called Lister Screen method,
was developed to detect Listeria spp. in food [162]. This method separates
Listeria cells from enriched food samples by means of immunomagnetic beads.
After magnetic capture, the beads are spread on PALCAM agar. The analysis
time, including an 18-h enrichment and plate incubation, is 48 h for positive
samples and 72 h for negative samples.
Recently, continuous production of daizein and genstein from soybean in a
magnetically stabilized fluidized bed bioreactor was reported [163]. Brodelius
[164] previously demonstrated the use of plant cells in MSFB bioreactor.
Another potential application of magnetic particle separation technology is
the use of magnetically delivered therapeutics. Carrier systems for the delivery
of chemotherapeutic agents by magnetic means have already been developed.
Carrier holding the drug can be concentrated at the desired site in vivo by a
magnetic field. Such a delivery system achieves a local accumulation of the
drug, which is comparable to that achieved by administration of a 100-fold
higher dose of the free drug [165].
Similarly, electrophoretic methods are also finding increasing applications in
other areas. For instance, electrophoretic processes are established techniques
for the dewatering of fine clays and latexes. Electrically enhanced liquid-liquid
extraction was reported by Thornton [166]. Adaptation of this method for the
extraction of biochemicals was reported [167]. Greater clarification and faster
floc formation were claimed using electrocoagulation in comparison with conventional chemical methods [4].
6
Suggestions for Future Work
Development of equipment is a continual process involving development of
prototype models, testing, and elimination of unfeasible models and unworkable alternatives. The complexities of using an internal magnet (such as a stir
bar), namely the collection of particles having widely different characteristics
and magnetically induced particle aggregation, discouraged this approach, and
a more traditional dipole constant field and gradient approach was chosen. The
migration time at each station was found to be critical, both for the prevention
of aggregation in the field and for the free capture of specific particles.
Multistage Magnetic and Electrophoretic Extraction of Cells, Particles and Macromolecules
183
Casein hydrolysis in stirred tank reactors using chymotrypsin immobilized on
magnetic supports was studied. A comparison was made of the kinetics in batch
and continuous stirred tank reactors [160]. Two types of commercially available
magnetic separation devices were tested for use in catalyst recovery. HGMS enabled paramagnetic particles to be removed from a rapidly flowing liquid. The
filamentary matrix materials used (steel wool or expanded metal lath) provided
a large volume for trapping magnetic particles. In this way, Ni particles (3–7 mm
in diameter) can easily be separated from an aqueous suspension.
The ability of immobilized lectin-magnetic separation to improve methods
for the detection of Staphylococcus aureus, Salmonella enteritidis and Listeria
monocytogenes was reported [161]. A new assay, called Lister Screen method,
was developed to detect Listeria spp. in food [162]. This method separates
Listeria cells from enriched food samples by means of immunomagnetic beads.
After magnetic capture, the beads are spread on PALCAM agar. The analysis
time, including an 18-h enrichment and plate incubation, is 48 h for positive
samples and 72 h for negative samples.
Recently, continuous production of daizein and genstein from soybean in a
magnetically stabilized fluidized bed bioreactor was reported [163]. Brodelius
[164] previously demonstrated the use of plant cells in MSFB bioreactor.
Another potential application of magnetic particle separation technology is
the use of magnetically delivered therapeutics. Carrier systems for the delivery
of chemotherapeutic agents by magnetic means have already been developed.
Carrier holding the drug can be concentrated at the desired site in vivo by a
magnetic field. Such a delivery system achieves a local accumulation of the
drug, which is comparable to that achieved by administration of a 100-fold
higher dose of the free drug [165].
Similarly, electrophoretic methods are also finding increasing applications in
other areas. For instance, electrophoretic processes are established techniques
for the dewatering of fine clays and latexes. Electrically enhanced liquid-liquid
extraction was reported by Thornton [166]. Adaptation of this method for the
extraction of biochemicals was reported [167]. Greater clarification and faster
floc formation were claimed using electrocoagulation in comparison with conventional chemical methods [4].
6
Suggestions for Future Work
Development of equipment is a continual process involving development of
prototype models, testing, and elimination of unfeasible models and unworkable alternatives. The complexities of using an internal magnet (such as a stir
bar), namely the collection of particles having widely different characteristics
and magnetically induced particle aggregation, discouraged this approach, and
a more traditional dipole constant field and gradient approach was chosen. The
migration time at each station was found to be critical, both for the prevention
of aggregation in the field and for the free capture of specific particles.
Multistage Magnetic and Electrophoretic Extraction of Cells, Particles and Macromolecules
183