Nanotechnology: Wonderful Science, but No Free Lunch

December 1, 2013 - 6 minutes read

Nanotechnology is the study and application of ultra-fine or “nano-sized” particles (NSP). Although NSPs have been around since the beginning of time, their form and function was not discovered as such until the last few decades; first, probably as ultra-fine particles in diesel exhaust and welding fumes that exhibited interesting physical (not chemical) properties. As to form, NSPs can take many shapes (e.g., tubules, wires, spheres, branching dendrimers (think of branching neurons) or all manner of fixed or amorphous shapes), but all have in common at least one dimension of 100 nanometers (nm) or less. As a point of reference, a hair is 60,000 nm in diameter and a red blood cell is 6,000 nm; 100,000 NSPs lined up together would be equal to the thickness of a sheet of paper (~0.1 mm). At this very small dimension, the rules governing larger objects are changed; that is, because of the small size of the particle, the atoms comprising the particle are closer to the surface and tend to exert more individual force, with the result of conferring different net effects on an NSP as compared to a more macro-sized particle made of the same substance. We have now started to understand NSPs and exploit their behavior by producing stronger steel and plastic, smaller and faster computer chips, which require less power, more efficacious drugs, and we have developed new applications for food and supplement science as well, a few of which are described below:

 

  • Storage container improvement. Nano-sized clay particles embedded in plastic bottles do more than strengthen the bottle; they present a physical barrier to penetration of harmful ultraviolet light from fluorescent bulbs or natural sunlight and to the entry of oxygen molecules from the environment. Both ultraviolet light and oxygen can trigger oxidation and product degradation.
  • Product delivery enhancement. Large particle sizes, substances possessing certain electrical charges or certain solubility properties are often incompatible with the intestinal absorptive environment, but can be overcome by the application of nanotechnology by reducing the size or charge of the particle or through the use of nano-encapsulation, thus allowing for more efficient absorption. For example, only 17% of an oral dose of vitamin E is absorbed, but at the nano-dimension, 100% is absorbed, as if the vitamin was injected.
  • Texture, emulsions, spread-ability and “naturalness.” Reduction in food molecule particle size exposes more surface area and allows for more efficient formation of emulsions without addition of synthetic ingredients and loss of the opportunity to add “all natural” to the labels. Double-emulsions enhance spread-ability, mouth-feel and a smoother texture.
  • Ingredient protection in hostile environments through nano-encapsulation. Nano-encapsulation protects labile substances such as esters or proteins from hostile environments, including the acidity of the stomach or enzymes and surfactants of the intestine. Nano-encapsulation allows these delicate substances to arrive at their absorption destination without damage and can thus be added to the original product at lower concentration – a boon, especially if these labile ingredients are costly.

 

The “no free lunch” of nanotechnology is often missed when presented in the blinding light of the significant advantages of nanotechnology applications. That is, the physical differences produced by NSPs that make them so attractive in applications likely also come into play when interacting with biological systems. For one, the different behavior of the particles in applications could mean that a previously known to be safe substance could be manifested as a toxic effect in the body. Also, much of the safety data we have is based on selective and rate-certain absorption – when something is totally absorbed over a short period of time, it may overwhelm the body’s ability to re-direct the substance to a safe place or excrete it or metabolize it to a more benign or useful substance. Likewise, small particles may gain access to hitherto “protected areas,” such as the fetus or brain, inaccessible to larger particles and whose toxicity at that particular location is not known. Because there is no free lunch, Food and Drug Administration (FDA) insists that while a particular substance might be approved for use as a “macro-particle,” its use as a nanoparticle needs to be scrutinized for safety. As to what an NSP means to FDA, among other things, the agency has published guidance indicating that if the functionality depends on the size of the particle (as is the case with nanotechnology applications), FDA stipulates manufacturers need to talk to the agency before launching the product. It is conceivable that if FDA discovers product use of nanotechnology through a third party, the substance could be declared an adulterant. Because an FDA counseling session could result in excessive demands for demonstration of safety in response to “what if” questions, it is prudent to anticipate the questions as much as possible and go into the counseling session with as much data as possible, a path forward and a rationale why the safety-in-use of the NSP is obvious.