421
• Higher stability as compared to classical emulsions [32].
• NPs with better-controlled particle size can be obtained.
• More reproducible methods of fabrication.
Production of NPs Employing Supercritical Fluid (SCF)
Technology
SCF has been employed as another fascinating means to formulate NPs of biodegradable nature. This method is considered environmentally safer because unlike
conventional techniques it avoids the need for toxic organic solvents. It is classified
into two techniques depending upon the role of the supercritical CO 2 in the method
as either a solvent or an anti-solvent for rapid expansion of supercritical solutions
(RESS) or as an anti-solvent for supercritical anti-solvent process (SAS), respectively [52].
Supercritical Anti-Solvent (SAS)
A supercritical anti-solvent miscible organic solvent such as methanol is used for
the dissolution of the solute of interest. The solute must not be soluble in supercritical anti-solvent. The supercritical carbon dioxide (CO 2) is pumped into a precipitation vessel from high pressure to a certain pressure. Later, this solution containing
an active pharmaceutical ingredient (API), the polymer is sprayed via a nozzle in
the reactor (Fig. 25.8) [53–56]. The extraction of organic solvent by the SCF results
in prompt solute precipitation as NPs [57]. In this technique, the solvent power of a
polar organic solvent containing an active pharmaceutical ingredient (API) and the
polymer is decreased by saturating it with CO 2 at supercritical conditions. The CO 2
results in the precipitation and recrystallization of the API [58]. This approach
requires a long washing time before the agglomeration/aggregation of NPs. This
issue can be resolved by enhancing the mass transfer by achieving the intense mixing of supercritical anti-solvent and the solution. Another disadvantage of this technique is the residual toxic solvent in the product [59]. The advantages of this
approach are stated here:
• Feasible for the production of NPs on large scalable [60].
• Applicable to a wide range of APIs and polymers.
• Continuous process.
• Rapid contact between anti-solvent and the polymer solution fasten up the nucleation and growth processes, therefore forming smaller particles.
• Performed at room temperatures, hence prevents thermal degradation of the NPs
[61].
• Easy removal of the supercritical fluid from the system by lowering the pressure
or depressurizing ([61–63].
• Formulate drug-encapsulated NPs having high polymorphic purity [64].
25 Role of Nanoparticles in the Management of Metabolic Disorders
• Higher stability as compared to classical emulsions [32].
• NPs with better-controlled particle size can be obtained.
• More reproducible methods of fabrication.
Production of NPs Employing Supercritical Fluid (SCF)
Technology
SCF has been employed as another fascinating means to formulate NPs of biodegradable nature. This method is considered environmentally safer because unlike
conventional techniques it avoids the need for toxic organic solvents. It is classified
into two techniques depending upon the role of the supercritical CO 2 in the method
as either a solvent or an anti-solvent for rapid expansion of supercritical solutions
(RESS) or as an anti-solvent for supercritical anti-solvent process (SAS), respectively [52].
Supercritical Anti-Solvent (SAS)
A supercritical anti-solvent miscible organic solvent such as methanol is used for
the dissolution of the solute of interest. The solute must not be soluble in supercritical anti-solvent. The supercritical carbon dioxide (CO 2) is pumped into a precipitation vessel from high pressure to a certain pressure. Later, this solution containing
an active pharmaceutical ingredient (API), the polymer is sprayed via a nozzle in
the reactor (Fig. 25.8) [53–56]. The extraction of organic solvent by the SCF results
in prompt solute precipitation as NPs [57]. In this technique, the solvent power of a
polar organic solvent containing an active pharmaceutical ingredient (API) and the
polymer is decreased by saturating it with CO 2 at supercritical conditions. The CO 2
results in the precipitation and recrystallization of the API [58]. This approach
requires a long washing time before the agglomeration/aggregation of NPs. This
issue can be resolved by enhancing the mass transfer by achieving the intense mixing of supercritical anti-solvent and the solution. Another disadvantage of this technique is the residual toxic solvent in the product [59]. The advantages of this
approach are stated here:
• Feasible for the production of NPs on large scalable [60].
• Applicable to a wide range of APIs and polymers.
• Continuous process.
• Rapid contact between anti-solvent and the polymer solution fasten up the nucleation and growth processes, therefore forming smaller particles.
• Performed at room temperatures, hence prevents thermal degradation of the NPs
[61].
• Easy removal of the supercritical fluid from the system by lowering the pressure
or depressurizing ([61–63].
• Formulate drug-encapsulated NPs having high polymorphic purity [64].
25 Role of Nanoparticles in the Management of Metabolic Disorders