NanoSal
Use of the aerosol dispenser to deliver nanotechnological
salt actives for public health…
This paper was originally presented at the Aerosol & Dispensing Forum in New York.
Using the knowledge of microphysics and thermodynamics,
one can understand the advantages of the aerosol
applicator, compared to other dispensing systems, in
obtaining very small particle sizes on the micron scale. These can
lead to even smaller particles on the nanometer scale. A successful
case of nanotechnology meeting aerosols is a nanosalt with the
trade name “NanoSal,” an innovative application of table salt to
aerosol technology. It has the advantage of allowing a reduction
in the amount of salt ingested without a loss of taste quality. In
the short term, this results in the improvement and prevention of
hypertension with medium- and long-term benefits to the quality
of human life and public health.
What is nanotechnological material?
The term “nano” comes from the Greek, meaning “dwarf.” In
the metric system, one nanometer (nm) represents the billionth
part of a meter. In nanotechnology, such a particle is defined as a
small fraction of a solid substance, but which behaves in general
as a whole unit on a larger scale in terms of its properties. In
consumer products, ingredients can sometimes be found between
100nm and 1000nm.
As this technology is fairly recent, the substances are molecules
classified according to their composition—using their Chemical
Abstracts Service (CAS) number—and not according to their particle
size. This creates a lot of confusion between regulatory agents
in Brazil and several other countries when accepting the registrations
of sanitary consumer products with nanotechnological
claims, such as those found in the Household or Personal Care
categories, because ultimately, there is no chemical difference
between raw material and nanoparticulate raw material.
For example, on the larger side, sodium chloride (salt) can be
a giant grain, ideal for seasoning a good barbecue—or it can be
a smaller-scale nanoparticulate. Both will have the same NaCl
32 Spray October 2019
AntAl GyörGy Almásy
technical Director, Aeroservice ltd.
& VP of the Brazilian Aerosol
Association (ABAs)
CAS number (7647-14-5) for governmental and regulatory health
authorities.
However, nanoparticles on the smaller scale may have different
physicochemical and quantum properties than their counterparts
on the larger scale. This is relevant in the development
of consumer products since such differentiation can affect skin
absorption /permeation, increase hygroscopicity (a reaction to the
moisture content in the air that can swell nanoparticles), affect
chemical reactivity given the increase of contact surface of the
nanoparticle, change reflectance or the refractive index, etc.
Nanoparticles suspend in the air and thereby generate particles
that are potentially easier to inhale, which may pose risks that
need to be measured in terms of safety of use, efficacy and toxicology.
These must be evaluated with great responsibility by the
technical and scientific staff of the research, development and
innovation (RD&I) areas of the aerosol industry.
There are also applications in the public health field, such as
nanosalt food sprays and aerosol vaccines. Indeed, the aerosol
dispenser is a public health veteran with more than 77 years of
service to the world. We always approach these new possibilities
with great enthusiasm.
Microphysics applied to aerosols
The following is an attempt to simply explain the two partitioning
mechanisms that make aerosols the best choice for dispensing
nanotechnology actives.
Mechanical partitioning or mechanical break-up
Particles are produced through the passage of a liquid under
hydraulic pressure, which on their ultimate path to freedom, have
to pass through a narrow exit (the orifice of the actuator). There
is sometimes a whirling as the pressure increases due to the size
of the orifice. The particle is ultimately mechanically broken; this
is called a mechanical break-up and such phenomenon occur in
all pump valves used with perfumes, household cleaner trigger
sprayers (perfume’s less chic cousin) and in aerosol actuators—all
designed for atomization.
To obtain smaller particles, it is necessary to increase hydraulic
pressure and/or decrease the size of the actuator orifice. In
Mechanical break-up actuator