Biomedical Engineering Reference
In-Depth Information
7.3.2.3 Physicochemical Characteristics of Polymers/Lipids Utilized in Nanoparticles
Table 7.5 lists different physicochemical parameters important for characterizing toxicity of
nanoparticles. It is very important to extensively characterize the composition, shape, surface area,
surface charge, and so on along with the size of PNs and SLNs. During nanoparticles development,
the focus is to develop particles that contain at least one dimension smaller than 100 nm with high
reproducibility and monodispersity. These nanoparticles could have a number of possible causes of
toxicity: (1) nanoparticles have been demonstrated to have electronic, optical, and magnetic proper-
ties that are related to their physical dimensions, and the breakdown of these nanoparticles could
lead to a unique toxic effect that is difficult to predict [74]; (2) nanoparticles surfaces are involved
in many catalytic and oxidative reactions [75]. If these reactions induce cytotoxicity, then the tox-
icity could be greater than a similar bulk material because the surface-area-to-volume ratio for
nanoscale material is much greater and (3) some nanoparticles contain metals or compounds with
known toxicity and, thus, the breakdown of these materials could elicit similar toxic responses to
the components themselves.
Ideally, FDA (Food and Drug Administration)-approved or GRAS (generally regarded as
safe)-listed polymers are utilized for the preparation of PNs and SLNs for drug delivery systems.
Table 7.6 lists various polymers and lipids considered to be safe and commonly used in preparing
nanoparticles.
Further, there is a consistent and increasing use of new polymers/lipids, which enhances the effi-
ciency of these nanoparticles but the safety of these materials remains a concern as very little time
and effort are devoted in this direction.
TABLE 7.5
Lists of Different Physicochemical Parameters Important for Characterizing Toxicity
of Nanoparticles
Interaction of Nanoparticles with Biological Medium
What does the material look like?
• Particle size/size distribution
• Agglomeration state/aggregation
• Shape
What is the material made of?
• Overall composition (including chemical composition and crystal structure)
• Surface composition
• Purity (including levels of impurities)
What factors affect how a material interacts with its surroundings?
• Surface area
• Surface chemistry, including reactivity, hydrophobicity
• Surface charge
Overarching considerations to take into account when characterizing engineered nanomaterials in toxicity studies:
• Stability—how do material properties change with time (dynamic stability), storage, handling, preparation, delivery,
and so on? Include solubility, and the rate of material release through dissolution
• Context/media—how do material properties change in different media; that is, from the bulk material to dispersions
to material in various biological matrices? (“as administered” characterization is considered to be particularly
important)
• Where possible, materials should be characterized sufficiently to interpret the response to the amount of material
against a range of potentially relevant dose metrics, including mass, surface area, and number concentration
Source:
D.R. Boverhof, R.M. David,
Analytical and Bioanalytical Chemistry
, 396, 2010, 953-961.
