Composition and Structure - Lipid Nanoparticles: Production, Characterization and Stability - page 13

Table 2.1 Lipids used in the preparation of lipid nanoparticles
Fatty acids

Waxes

Dodecanoic acid
Myristic acid
Palmitic acid
Stearic acid

Cetyl palmitate
Carnauba wax
Beeswax
Liquid lipids

Soya bean oil
Oleic acid
Medium chain triglycerides (MCT)/caprylic- and
capric triglycerides
α -tocopherol/Vitamin E
Squalene
Hydroxyoctacosanylhydroxystearate
Isopropyl myristate

Monoglycerides

Glyceryl monostearate
Glyceryl hydroxystearate
Glyceryl behenate
Diglycerides
Glyceryl palmitostearate
Glyceryl dibehenate
Triglycerides Cationic lipids

Stearylamine (SA)
Benzalkonium chloride (alkyl dimethyl benzyl ammonium
chloride, BA)
Cetrimide (tetradecyl trimethyl ammonium bromide, CTAB)
Cetyl pyridinium chloride (hexadecyl pyridinium
chloride, CPC)
Dimethyl dioctadecyl ammonium bromide (DDAB)
N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethyl ammonium
chloride (DOTAP)

Caprylate triglyceride
Caprate triglyceride
Glyceryl tristearate/Tristearin
Glyceryl trilaurate/Trilaurin
Glyceryl trimyristate/Trimyristin
Glyceryl tripalmitate/Tripalmitin
Glyceryl tribehenate/Tribehenin

to infer electrostatic stability, whilst non-ionic surfactants are traditionally thought
to infer steric repulsion stability. In reality, the situation is much more complex
and many non-ionic surfactants used are too small to infer genuine steric stability,
but probably result in stability through the Gibbs-Marangoni effect (Walstra 1993 ).
Members from the Pluronic ® and Tween ® families are the most commonly
used non-ionic surfactants. As discussed, most of these surfactants contain a
hydrophilic moiety (ethylene oxide) and a hydrophobic moiety (hydrocarbon
chain).
Phospholipids and phosphatidylcholines are the common amphoteric sur-
factants employed in lipid nanoparticle preparation. These surfactants have both
negatively and positively charged functional groups. They exhibit features of a cat-
ionic and an anionic surfactant at low and high pH conditions, respectively.
Selection of surfactants for nanoparticle preparation depends on a number of
factors, including

• Intended route of administration
• HLB value of surfactant
• Effect on lipid modiication and particle size
• Role in in vivo degradation of the lipid