C hapter 10 nanomaterial product Forms and Functions
462
Many critical issues in both designing and assessing the positive
and negative effects of various cosmetic applications hinge around
understanding how far some type of applied-on-contact active
ingredient penetrates the skin and how it interacts with the penetrated layer. Penetrations can be positive, as in some skin-based
drug-delivery systems, or potentially negative if harmful side effects
occur. We know from experience, for example, that many particles
found in nature can cause allergic reactions in humans, resulting
from some type of penetration through the skin (by absorption
or other paths). How and whether penetration occurs depend on
many factors. Small particles have a greater likelihood for penetrating the skin than do larger ones, but there are many other factors
relating to both the body and to the surrounding environment (e.g.,
temperature) that effect whether penetration occurs.
As we’ve seen, the field of cosmetics can be exceedingly complex. It
is also a huge and secretive industry. Significant amounts of research
are ongoing with respect to the many factors we’ve, including the
way various formulations interact with complex skin systems. The
large surface-to-volume ratio of nanomaterials makes them particularly attractive for use in as either vehicles or active ingredients, as
does the catalysis characteristics of many.
Perhaps one of the most common examples of a widespread use
of nanomaterials in cosmetics is that of the ever-increasing use of
nanosized titanium dioxide or zinc oxide particles in sunscreens. A
nanopowder form of zinc oxide is shown in Figure 10.50. As noted,
normal titanium dioxide and zinc oxides have long been used as
blocking agents in many sunscreens. Applications have suffered,
however, from nonuniformity and a visible whitish discoloration.
Titanium dioxide nanoparticles, however, are essentially transparent, since their sizes are near the wavelengths of light. Sunscreens
based on these nanoparticles are much clearer, but at the same time
they retain their protective power. Concerns about health impacts,
however, have been raised (see the following discussion and
Chapter 11).
A whole range of nanomaterial types and forms is being explored
for use as vehicles or carriers for active ingredients. Use of nanomaterials can allow carrying various types of active ingredients without
degradation as well as offering better control of release rates. Small
sizes allow them to more easily be incorporated into outer skin
layers. Nanocapsules with polymeric membranes are in wide use.
Active ingredients are in cores. Release rates can be controlled by
462
Many critical issues in both designing and assessing the positive
and negative effects of various cosmetic applications hinge around
understanding how far some type of applied-on-contact active
ingredient penetrates the skin and how it interacts with the penetrated layer. Penetrations can be positive, as in some skin-based
drug-delivery systems, or potentially negative if harmful side effects
occur. We know from experience, for example, that many particles
found in nature can cause allergic reactions in humans, resulting
from some type of penetration through the skin (by absorption
or other paths). How and whether penetration occurs depend on
many factors. Small particles have a greater likelihood for penetrating the skin than do larger ones, but there are many other factors
relating to both the body and to the surrounding environment (e.g.,
temperature) that effect whether penetration occurs.
As we’ve seen, the field of cosmetics can be exceedingly complex. It
is also a huge and secretive industry. Significant amounts of research
are ongoing with respect to the many factors we’ve, including the
way various formulations interact with complex skin systems. The
large surface-to-volume ratio of nanomaterials makes them particularly attractive for use in as either vehicles or active ingredients, as
does the catalysis characteristics of many.
Perhaps one of the most common examples of a widespread use
of nanomaterials in cosmetics is that of the ever-increasing use of
nanosized titanium dioxide or zinc oxide particles in sunscreens. A
nanopowder form of zinc oxide is shown in Figure 10.50. As noted,
normal titanium dioxide and zinc oxides have long been used as
blocking agents in many sunscreens. Applications have suffered,
however, from nonuniformity and a visible whitish discoloration.
Titanium dioxide nanoparticles, however, are essentially transparent, since their sizes are near the wavelengths of light. Sunscreens
based on these nanoparticles are much clearer, but at the same time
they retain their protective power. Concerns about health impacts,
however, have been raised (see the following discussion and
Chapter 11).
A whole range of nanomaterial types and forms is being explored
for use as vehicles or carriers for active ingredients. Use of nanomaterials can allow carrying various types of active ingredients without
degradation as well as offering better control of release rates. Small
sizes allow them to more easily be incorporated into outer skin
layers. Nanocapsules with polymeric membranes are in wide use.
Active ingredients are in cores. Release rates can be controlled by