20. Transmission electron microscopy (TEM) is commonly used to
view the morphology and establish homogeneity and size distribution of nanocomplexes. Scanning electron microscopy
(SEM) and High Resolution Transmission Electron Microscopy (HRTEM) can also be employed, but from our experience they have been more suitable to view the nanocarriers on
their own.
21. Staining with 0.5% uranyl acetate for lipid-based nanocomplexes may be required as they are not as dense as metal
nanoparticles [26]. Cryo-TEM is also another option that
works well for most nanocomplexes.
22. The Stokes-Einstein equation was used to determine particle
size distribution based on tracking the trajectories of particles
in Brownian motion within the laser scatter volume [24].
23. Zeta potentials is calculated from the mean electrophoretic
mobility using Smoluchowski approximation which is based
on Laser-Doppler microelectrophoresis [24]. Particle concentrations are estimated based on the number of particles in the
field of view in relation to the scattering volume. These calculations generally are done by the associated software of the NTA
instrument.
24. The zeta potential values greater than +30 mV or less than
À30 mV are indicative of excellent colloidal stability
[28]. Note that Dynamic light Scattering (DLS) can also be
used to obtain size and zeta potential.
25. The sizes of nanocomplexes from TEM and NTA often differ.
This can be due to the fact that TEM measures the samples in a
dry state while NTA measures samples in an aqueous medium
[29]. NTA sizes may be closer to that in an in vivo system.
Acknowledgments
Research conducted in this area was partly funded by the National
Research Foundation of South Africa (Grant ID 81289). The
postgraduate students of the Nano-Gene and Drug Delivery
Group are acknowledged for their contribution in optimizing the
protocols described.
References
1. Conti M, Tazzari V, Baccini C, Pertici G, Serino LP, De Giorgi U (2006) Anticancer drug
delivery with nanoparticles. In Vivo
20:697–702
2. Brown MD, Sch€ atzlein AG, Uchegbu IF
(2001) Gene delivery with synthetic
(non-viral) carriers. Int J Pharm 229:1–21
3. Felgner PL, Gadek TR, Holm M, Roman R,
Chan HW, Wenz M, Northrop JP, Ringold
GM, Danielson M (1987) Lipofection: a highly
efficient lipid-mediated DNA-transfection procedure. Proc Natl Acad Sci U S A
84:7413–7417
54
Moganavelli Singh
view the morphology and establish homogeneity and size distribution of nanocomplexes. Scanning electron microscopy
(SEM) and High Resolution Transmission Electron Microscopy (HRTEM) can also be employed, but from our experience they have been more suitable to view the nanocarriers on
their own.
21. Staining with 0.5% uranyl acetate for lipid-based nanocomplexes may be required as they are not as dense as metal
nanoparticles [26]. Cryo-TEM is also another option that
works well for most nanocomplexes.
22. The Stokes-Einstein equation was used to determine particle
size distribution based on tracking the trajectories of particles
in Brownian motion within the laser scatter volume [24].
23. Zeta potentials is calculated from the mean electrophoretic
mobility using Smoluchowski approximation which is based
on Laser-Doppler microelectrophoresis [24]. Particle concentrations are estimated based on the number of particles in the
field of view in relation to the scattering volume. These calculations generally are done by the associated software of the NTA
instrument.
24. The zeta potential values greater than +30 mV or less than
À30 mV are indicative of excellent colloidal stability
[28]. Note that Dynamic light Scattering (DLS) can also be
used to obtain size and zeta potential.
25. The sizes of nanocomplexes from TEM and NTA often differ.
This can be due to the fact that TEM measures the samples in a
dry state while NTA measures samples in an aqueous medium
[29]. NTA sizes may be closer to that in an in vivo system.
Acknowledgments
Research conducted in this area was partly funded by the National
Research Foundation of South Africa (Grant ID 81289). The
postgraduate students of the Nano-Gene and Drug Delivery
Group are acknowledged for their contribution in optimizing the
protocols described.
References
1. Conti M, Tazzari V, Baccini C, Pertici G, Serino LP, De Giorgi U (2006) Anticancer drug
delivery with nanoparticles. In Vivo
20:697–702
2. Brown MD, Sch€ atzlein AG, Uchegbu IF
(2001) Gene delivery with synthetic
(non-viral) carriers. Int J Pharm 229:1–21
3. Felgner PL, Gadek TR, Holm M, Roman R,
Chan HW, Wenz M, Northrop JP, Ringold
GM, Danielson M (1987) Lipofection: a highly
efficient lipid-mediated DNA-transfection procedure. Proc Natl Acad Sci U S A
84:7413–7417
54
Moganavelli Singh