429
charged moieties within the center or surface adsorption. Neutral NPs have zeta
potential ranging −10 to +10 mV, NPs with zeta potentials > +30 mV are regarded
as strongly cationic. While NPs with a zeta potential < −30 mV are regarded
strongly anionic. Because of the negative charge of most cellular membranes, zeta
potential can affect the tendency of NPs to cross cellular membranes, cell wall disruption is generally caused by NPs having a cationic charge.
Surface Hydrophobicity
NPs with surface hydrophobicity on administration by intravenously (IV) are
unavoidably removed by the mononuclear phagocyte system (MPS). To avoid the
phagocytosis of NPs and their ultimate removal from circulation upon IV administration, the surface of NPs should be modified. To solve this problem two tactics are
employed. One method includes the use of hydrophilic polymers such as chitosan,
polyethylene glycol (PEG), or stabilizers, e.g. poloxamines or poloxamers for the
surface coating of particles. The second method is employing biodegradable copolymers with hydrophilic blocks such as PLA-PEG. NPs surface modification with
PEG gives stealth features to NPs; hence, they are not destroyed by macrophages,
therefore, named “stealth NPs.” Surface hydrophobicity can be estimated by several
approaches, as stated below:
• Contact angle determination.
• Hydrophobic interaction chromatography.
• X-ray photon correlation technique.
• Biphasic partitioning, adsorption of probes.
Drug Loading
The drug can be loaded by two approaches: the adsorption/absorption method and
the incorporation technique. Encapsulation efficiency and drug content of NPs are
affected by numerous factors, as described below:
• The molecular weight of the drug.
• Polymer–drug interaction.
• The solubility of the drug in the polymer matrix.
• The existence of end carboxylic groups.
Drug Release
Depending upon the nature of polymers (Table 25.2), polymeric NPs have distinguishing applications of the controlled and sustained release drug delivery [79].
Several factors influence the release of drug, i.e. desorption, the solubility of the
25 Role of Nanoparticles in the Management of Metabolic Disorders
charged moieties within the center or surface adsorption. Neutral NPs have zeta
potential ranging −10 to +10 mV, NPs with zeta potentials > +30 mV are regarded
as strongly cationic. While NPs with a zeta potential < −30 mV are regarded
strongly anionic. Because of the negative charge of most cellular membranes, zeta
potential can affect the tendency of NPs to cross cellular membranes, cell wall disruption is generally caused by NPs having a cationic charge.
Surface Hydrophobicity
NPs with surface hydrophobicity on administration by intravenously (IV) are
unavoidably removed by the mononuclear phagocyte system (MPS). To avoid the
phagocytosis of NPs and their ultimate removal from circulation upon IV administration, the surface of NPs should be modified. To solve this problem two tactics are
employed. One method includes the use of hydrophilic polymers such as chitosan,
polyethylene glycol (PEG), or stabilizers, e.g. poloxamines or poloxamers for the
surface coating of particles. The second method is employing biodegradable copolymers with hydrophilic blocks such as PLA-PEG. NPs surface modification with
PEG gives stealth features to NPs; hence, they are not destroyed by macrophages,
therefore, named “stealth NPs.” Surface hydrophobicity can be estimated by several
approaches, as stated below:
• Contact angle determination.
• Hydrophobic interaction chromatography.
• X-ray photon correlation technique.
• Biphasic partitioning, adsorption of probes.
Drug Loading
The drug can be loaded by two approaches: the adsorption/absorption method and
the incorporation technique. Encapsulation efficiency and drug content of NPs are
affected by numerous factors, as described below:
• The molecular weight of the drug.
• Polymer–drug interaction.
• The solubility of the drug in the polymer matrix.
• The existence of end carboxylic groups.
Drug Release
Depending upon the nature of polymers (Table 25.2), polymeric NPs have distinguishing applications of the controlled and sustained release drug delivery [79].
Several factors influence the release of drug, i.e. desorption, the solubility of the
25 Role of Nanoparticles in the Management of Metabolic Disorders