Nanomedicine characterisation/functionalisation - WIP! Flashcards
(9 cards)
What are carbon nanotubes?
Cylindrical fullerenes with dimension in the nanoscale, composed of carbon atoms arranged in a hexagonal lattice.
Found in 2 forms – single walled, and multi walled:
SWCNTs – single sheet of sp2 hybridized carbon atoms, with a diameter of 0.4-2.0 nm
MWCNTs – concentric layers of SWCNTs, with inner diameter 1-3 nm and outer diameter 2-100nm
Describe the application of CNTs in medicine
Thermal treatment of cancer - proteins with membrane-bound receptors can be targeted. E.g. transferin is often targeted for cancer treatment as it is overexpressed in many cancers.
CNTs
promising antioxidant
Drug delivery - high surface area, high chemical stability, able to adsorb or conjugate with a variety of therapeutic molecules. penetrate cells directly and keep drug intact without metabolism. safer and more effective than traditional methods
What are the physical properties of nanoparticles?
Mean size, size distribution
Shape and morphology
Surface charge (zeta potential can be measured as a proxy) - if there is no surface charge they are likely to collapse into other nanoparticles (aggregate)
Physical stability – constant properties? Aggregation? Change in morphology?
What are some methods of chemical characterisation of nanoparticles?
XDR (x-ray diffraction) - crystalline structure of nanoparticles
XPS (x-ray photoelectron spectroscopy) - element and surface composition
SEM-EDX – elemental and surface composition
NMR – chemical and surface composition
FTIR – surface composition
Raman spec – surface composition
ICP-OES (inductively coupled plasma – optical emission spectroscopy) or ICP-MS - elemental composition, mass concentration
HPLC – chemical composition
UV-vis spectroscopy – optical properties, nanoparticle concentration
Describe transmission electron microscopy as a technique for nanoparticle characterisation
< 0.5nm resolution, 4 million times better than naked eye
Electron source in vacuum for imaging, focused using electromagnetic lenses into sample, CCD camera, can digitally convert image
Sample is made of materials, some of which can absorb electrons, some cannot
Sample prep – sample solution pipetted onto carbon coated grid, dried and loaded under vacuum conditions. carbon membrane on grid can absorb sample, and doesn’t absorb electrons.
Negative staining – sample embedded by a dried amorphous layer of heavy metal-containing cationic or anionic salt. Provides contrast for example when the nanoparticles do not absorb electrons enough
Cryo-EM – sample cooled to cryogenic temperatures (do not add any contrast, so requires very powerful microscopes compared to negative staining) and embedded into an environment of vitreous water. No drying preserves the structure. Mostly used for structural biology (direct imaging of macromolecules)
Pros – near atomic resolution, direct and accurate measurement nanoparticle size distribution, provides information about shape/morphology of nanoparticles
Cons – sample processing may alter nanoparticles or generate artifacts, dried samples are far from native conditions, time consuming, expensive to run/buy and may have a massive footprint
Describe atomic force microscopy as a technique for nanoparticle characterisation *
Describe dynamic light scattering as a technique for nanoparticle characterisation *
Determining size distribution of nanoparticles using Brownian motion.
Diffusion coefficient is directly proportional to the temperature
If a particle is non-spherical it still moves with the same Brownian motion
Pros – fast routine method, benchtop instrument, accessible cost, almost no training needed, nanoparticles are in solution in their native environment, direct and accurate measurement of nanoparticle size distribution
Cons – no information about shape/morphology of nanoparticles, the hydrodynamic diameter is larger than the solid diameter (?), the scattering intensity is proportional to the 6th power of the size:aggregates (large debris affect the accuracy), unsuitable for polydisperse particles
Describe nanoparticle tracking analysis as a technique for nanoparticle characterisation *
Pros – opposite to DLS (can deal with polydisperse particles), benchtop instrument, accessible cost, direct and accurate measurement of nanoparticle size distribution
Cons – more time consuming than DLS, particle concentration must be within a precise window (sample dilution may alter the properties), no information about shape/morphology, the hydrodynamic diameter is larger than the solid diameter (?), large debris may prevent analysis
Describe electrophoretic light scattering as a technique for nanoparticle characterisation *
Doppler effect
measures zeta potential
