A crash Course by Christina Mossaad, PhD


First lesson in nanotechnology is what qualifies as being in the nano-club?

Nanoparticles are considered particles under 100nm. Until imaging techniques such as electron microscopy and light scattering were developed, the classification of these particles was difficult. Most commonly dynamic light scattering and static light scattering are employed to determine particle size distribution within a given solution or slurry. Additionally the BET Surface Area analysis method has a backdoor calculation to determine average particle size including that of particles below 20nm which can be tricky when agglomeration happens in other methods!

What makes nano size range vs micro size range behave differently?

The particles interact on a molecular and atomic level with many different systems, diverging from conventional micro and macroparticle behavior norms of the same material.


Where is nanoscale advantageous?

  • Drug concentration
  • Controlled and targeted drug delivery
  • Higher solubility and bioavailability in pharma applications
  • Transdermal drug delivery with certain molecules/drugs
  • Can be used for enhanced materials properties such as higher strength, enhanced electrical or photocatalytic properties and more in various fields
  • Enhanced cellular interaction and healing
  • Higher surface area affords many advantages in many fields including cosmetics and sunscreen
  • Enhanced wound healing properties

Where is nanoscale at a disadvantage or detrimental?

  • Nanoparticles can cause immune responses and macrophage recruitment
  • Has had inquiries of safety when used in sunscreen (cell penetration concerns) (references below countering this)
  • Inhalation of nanoparticles is hazardous
  • Long term (>50 years) exposure risk is unknown
  • Nanotoxicology is still an emerging field


Are there concerns with it being in cosmetics and sunscreen?

Many blogs exist to up play this fear, but research is showing it is unfounded to date. ZnO and TiO2 have shown not to penetrate dermal layers to reach the blood stream. More recently, a silver nanoparticle preservative has been developed for the targeted use in cosmetics, showing a promising future of the incorporation of nanoparticles within safe guidelines.


More Reading and Resources:

History of EM:

Nanoparticle overview:

Non transdermal TiO2 or ZnO found

Strategies for safety evaluations

Nanoparticles in sunscreen pose no health risk

Nanotoxicology is a growing field to address this research

Silver nanoparticles as a preservative

Wound healing improvements