Biomedical Engineering Reference
In-Depth Information
af ect the characteristics and biologic properties of lipid nanoemulsions.
h e nanoemulsions are stable for a long period, with good size, oxidation
status, and cell survival and uptake in all tested cell lines [127]. Kou
et al.
have shown the ef ect of nanoemulsions of antioxidant synergy formula-
tion (ASF) containing gamma, alpha, and delta tocopherol, and suggested
enhanced anti-inl ammatory properties and bioavailability with gamma
tocopherol as compared to their normal suspensions [128]. Drug deliv-
ery systems have the ability to allow superior drug absorption, controlled
drug release and reduced side-ef ects, enhancing the ef ectiveness using
nano-enabled systems such as micelles, nanoemulsions, nanogels, lipo-
somes, nanoi bers, and dendrimers [129]. h e pharmaceutical nanocarri-
ers, such as liposomes, micelles, nanoemulsions, polymeric nanoparticles
and many others, show a variety of useful properties such as longevity
in the blood allowing for their accumulation in pathological areas with
compromised vasculature; specii c targeting to certain disease sites due
to various targeting ligands attached to the surface of the nanocarriers;
enhanced intracellular penetration with the help of surface-attached cell-
penetrating molecules; contrast properties due to the carrier loading with
various contrast materials allowing for direct carrier visualization
in vivo
;
stimuli-sensitivity allowing for drug release from the carriers under certain
physiological conditions, and others. h e enginnering of multifunctional
pharmaceutical nanocarriers combinig several useful preoperties in one
particle can signii cantly enhance the ei cacy of many therapeutic and
diagnostic protocols [130].
6.9 Nanoi bers
Nanoi bers may be designed to present high densities of bioactive mole-
cules such as those which promote cell adhesion and growth. For example,
amphiphiles that present the pentapeptide epitope IKVAV, an amino acid
sequence of laminin that promotes neurite adhesion, can self-assemble in
aqueous media, or when injected directly into a tissue, form i bers with
a diameter of 5-10 nm. Indeed, these scaf olds were shown to induce
rapid dif erentiation of cells to neurons, while discouraging the develop-
ment of astrocytes. h is presumably suggests that synthetic materials may
have the ability to modulate selective gene expression. Another interest-
ing approach was the design of a synthetic collagen substitute, based on
a material composed of a long hydrophobic alkyl group on one end and a
hydrophilic peptide on the other that self-assembles into nanocylindrical
structures. h ese nanocylinders guided the formation of hydroxyapatite
