423
Dialysis
This technique involves a solvent displacement mechanism but in contrast to the
conventional nanoprecipitation method (Fig. 25.9). It includes additional tools such
as a dialysis bag/semi-permeable membrane [67]. Polymer, drug, and surfactant are
dissolved in the same organic solvent and are loaded into a proper molecular weight
cutoff dialysis bag [68]. A solvent which is non-solvent of the polymer but miscible
with the polymer solvent is used for dialysis. The dialysis membrane with suitable
molecular weight cutoff will act as a physical barrier for the polymer but will allow
the movement of the solvent inside. Hence, the loss of solubility of the polymer and
aggregation of the polymer will occur resulting in homogeneous suspensions of
NPs [21]. This nanoprecipitation method has been successfully employed to entrap
several drugs such as doxorubicin, retinoic acid, paclitaxel, curcumin, gentamicin,
clonazepam as well as various hydrophobic drugs [69–74]. Furthermore, drugs having hydrophilic nature such as proteins and peptides show decrease solubility in the
organic phase. Therefore, this technique cannot be employed for the loading of
drugs of hydrophilic nature into NPs. It is an effective and simple technique for the
fabrication of small, finely distributed polymeric NPs [67]. It does not involve the
use of any sophisticated material. An increased concentration of NPs (by factors
from 10 to 50) in suspension can be achieved from initial formulation values without involving NPs aggregation [32]. Before and after NPs formation drug easily
releases from the dialysis membrane [75].
Separation Techniques of NPs
Depending on the technique of fabrication, separation of NPs from the free drug and
polymer aggregates has been achieved by using different methods, such as ultracentrifugation, dialysis, cross-flow microfiltration, diafiltration, gel filtration, and
dialysis.
Stability of NPs
It is influenced by several physical and chemical characteristics, as discussed below:
Physical Stability
The opposition of the gravitational forces by Brownian motion prevents the sedimentation of the colloidal size particles, therefore the suspended particles of different contents, zeta potential, and morphology randomly collide resulting in settling
25 Role of Nanoparticles in the Management of Metabolic Disorders
Dialysis
This technique involves a solvent displacement mechanism but in contrast to the
conventional nanoprecipitation method (Fig. 25.9). It includes additional tools such
as a dialysis bag/semi-permeable membrane [67]. Polymer, drug, and surfactant are
dissolved in the same organic solvent and are loaded into a proper molecular weight
cutoff dialysis bag [68]. A solvent which is non-solvent of the polymer but miscible
with the polymer solvent is used for dialysis. The dialysis membrane with suitable
molecular weight cutoff will act as a physical barrier for the polymer but will allow
the movement of the solvent inside. Hence, the loss of solubility of the polymer and
aggregation of the polymer will occur resulting in homogeneous suspensions of
NPs [21]. This nanoprecipitation method has been successfully employed to entrap
several drugs such as doxorubicin, retinoic acid, paclitaxel, curcumin, gentamicin,
clonazepam as well as various hydrophobic drugs [69–74]. Furthermore, drugs having hydrophilic nature such as proteins and peptides show decrease solubility in the
organic phase. Therefore, this technique cannot be employed for the loading of
drugs of hydrophilic nature into NPs. It is an effective and simple technique for the
fabrication of small, finely distributed polymeric NPs [67]. It does not involve the
use of any sophisticated material. An increased concentration of NPs (by factors
from 10 to 50) in suspension can be achieved from initial formulation values without involving NPs aggregation [32]. Before and after NPs formation drug easily
releases from the dialysis membrane [75].
Separation Techniques of NPs
Depending on the technique of fabrication, separation of NPs from the free drug and
polymer aggregates has been achieved by using different methods, such as ultracentrifugation, dialysis, cross-flow microfiltration, diafiltration, gel filtration, and
dialysis.
Stability of NPs
It is influenced by several physical and chemical characteristics, as discussed below:
Physical Stability
The opposition of the gravitational forces by Brownian motion prevents the sedimentation of the colloidal size particles, therefore the suspended particles of different contents, zeta potential, and morphology randomly collide resulting in settling
25 Role of Nanoparticles in the Management of Metabolic Disorders