412
Materials Employed for the Fabrication of NPs
They can be fabricated by means of several materials, i.e. metals (silicon, silver,
gold, and platinum), lipids, and polymers. Virus-based NPs have also been developed by researchers for tissue-specific targeting [15]. Polymers have a significant
role in the delivery of low molecular weight moieties and macromolecules due to
incredible development in the polymer chemistry arena. Synthetic and natural polymers are two broad classes of polymeric materials.
The selection of suitable materials for the formulation of NPs depends upon
consideration of the features [16], as mentioned below:
• The desired particle size for the delivery system.
• Stability and aqueous solubility of drugs.
• Antigenicity of the polymers.
• Toxicity profile and biocompatibility of polymer.
• The desired surface features of the particle.
• Desired drug release characteristics.
• The degree of polymer biodegradation.
Methods of NPs Fabrication
Emulsification-Solvent Evaporation Method
Water-immiscible, volatile organic solvent, e.g. dichloromethane was used for the
dissolution of the polymer. Then, the drug is encapsulated either by dispersing/dissolving it into a polymer organic solution to form organic phase and this organic
phase is then added as droplets in external phase containing surfactant, i.e. pluronic,
tween 80, and polyvinyl alcohol (PVA) solution to prepare o/w emulsion.
Nanospheres are formed on the precipitation of polymer, later organic solvent is
removed by stirring or rotary evaporator under reduced pressure (Fig. 25.1) [17].
Several parameters influence the particle size, i.e. temperature, rate of stirring,
conc., surfactant nature, and the viscosity of the organic and aqueous phase. In a
study, polycaprolactone (PCL) and Poly-L-lactic acid (PLLA) based polymeric
nanoparticles (PNPs) were the smallest particles reported having a diameter of
76 nm in the case of PLGA with sodium dodecyl sulfate (SDS) as being employed
as a surfactant. On the other hand, PCL NPs were reported with the largest particles
[18]. It is not feasible to encapsulate hydrophilic compounds with high loading
efficiency by commonly utilized methods/single emulsion technique (Fig. 25.2)
because of the rapid partitioning of the moieties to the outer phase. To overcome this
issue, a double emulsion technique (Fig. 25.3) is usually employed [19]. This simple method has flexibility in the selection of the solvent and the surfactant for the
Z. Iqbal et al.
Materials Employed for the Fabrication of NPs
They can be fabricated by means of several materials, i.e. metals (silicon, silver,
gold, and platinum), lipids, and polymers. Virus-based NPs have also been developed by researchers for tissue-specific targeting [15]. Polymers have a significant
role in the delivery of low molecular weight moieties and macromolecules due to
incredible development in the polymer chemistry arena. Synthetic and natural polymers are two broad classes of polymeric materials.
The selection of suitable materials for the formulation of NPs depends upon
consideration of the features [16], as mentioned below:
• The desired particle size for the delivery system.
• Stability and aqueous solubility of drugs.
• Antigenicity of the polymers.
• Toxicity profile and biocompatibility of polymer.
• The desired surface features of the particle.
• Desired drug release characteristics.
• The degree of polymer biodegradation.
Methods of NPs Fabrication
Emulsification-Solvent Evaporation Method
Water-immiscible, volatile organic solvent, e.g. dichloromethane was used for the
dissolution of the polymer. Then, the drug is encapsulated either by dispersing/dissolving it into a polymer organic solution to form organic phase and this organic
phase is then added as droplets in external phase containing surfactant, i.e. pluronic,
tween 80, and polyvinyl alcohol (PVA) solution to prepare o/w emulsion.
Nanospheres are formed on the precipitation of polymer, later organic solvent is
removed by stirring or rotary evaporator under reduced pressure (Fig. 25.1) [17].
Several parameters influence the particle size, i.e. temperature, rate of stirring,
conc., surfactant nature, and the viscosity of the organic and aqueous phase. In a
study, polycaprolactone (PCL) and Poly-L-lactic acid (PLLA) based polymeric
nanoparticles (PNPs) were the smallest particles reported having a diameter of
76 nm in the case of PLGA with sodium dodecyl sulfate (SDS) as being employed
as a surfactant. On the other hand, PCL NPs were reported with the largest particles
[18]. It is not feasible to encapsulate hydrophilic compounds with high loading
efficiency by commonly utilized methods/single emulsion technique (Fig. 25.2)
because of the rapid partitioning of the moieties to the outer phase. To overcome this
issue, a double emulsion technique (Fig. 25.3) is usually employed [19]. This simple method has flexibility in the selection of the solvent and the surfactant for the
Z. Iqbal et al.