Page 531 - Book Hosokawa Nanoparticle Technology Handbook

21 DEVELOPMENT OF FUNCTIONAL SKINCARE COSMETICS APPLICATIONS

Figure 21.3
Evaluation of Vitamin C delivery efficiency to dermis by
VC-IP encapsulated PLGA nanospheres.

encapsulating VC-IP in the PLGA nanospheres,
allowing them to pass through the horny layer and be
delivered stably through the skin. The VC-IP is grad-
ually released due to hydrolysis of PLGA and the
metabolism to pure vitamin C by esterase in the epi-
dermis and dermis. The immediate effect, however, is
attributed to the VC-IP on nanosphere surfaces. These
two effects enable PLGA nanospheres to be useful
nanoparticle carriers that can deliver pro-vitamin C to
hard-to-reach skin area and provide both immediate
and sustained cosmeceutical effects.
Figure 21.2 (3) Defense against UV by VC-IP encapsulated PLGA
Permeability comparison between micro dispersion and nanospheres
PLGA NS dispersion in water. Recently, owing to the depletion of ozone layer, a
larger amount of UV radiation (UV-A, 320–400 nm;
UV-B, 280–320 nm) reaches the Earth. UV-A can pen-
vitamin C were detected, and none would exist 18 h etrate the skin to dermis and cause damages to colla-
after the treatment. But, when applying VC-IP encap- gen and elastin from long-term exposure. Although
sulated PLGA nanospheres, the vitamin C could be UV-B does not penetrate to the dermis, it can cause
detected even 48 h after the treatment. Fig. 21.3 inflammation (sunburn) such as erythema and edema
shows the changes over time in the amount of reduced in a short time. Daily exposure may induce skin aging
Vitamin C at the dermis after applying the aqueous and skin cancer. For verifying the effect of vitamin C
dispersion containing 7.69 wt% of VC-IP encapsu- delivered to the skin tissue by PLGA nanospheres, we
lated PLGA nanospheres (D 215 nm) on the skin evaluated DNA double-strand breakages in the cell
50
samples in comparison to that of applying 1 wt% VC- nuclei. This experiment demonstrated the effective-
IP oil–water emulsion (D 276 nm). Both of them ness of applying VC-IP encapsulated PLGA nanos-
50
had a VC-IP concentration of 1.0 wt%. However, VC- pheres to control the DNA damage by UV irradiation.
IP encapsulated in the PLGA nanospheres was more The emulsion containing VC-IP encapsulated PLGA
effective than applied as it is. With the VC-IP encap- nanosphere was applied to human skin samples (from
sulated PLGA nanospheres, immediate effect could the back of the ear of a healthy 47-year-old woman),
be observed 2 h after the treatment; and, after 4 h its which were then given accelerated UV irradiation for
cumulative amount of vitamin C could reach 10 times several tens of seconds to provide a cumulative
of that applying VC-IP emulsion. This quantitatively amount equivalent to that a person could receive in a
showed the benefits of using PLGA nanospheres to day (UV-A, 200 J/cm²; UV-B, 2 J/cm²). The skin sam-
deliver vitamin C for skincare applications. ples were evaluated with the TUNEL method 24 h
If VC-IP is applied alone, the agglutination of its later. The TUNEL method selectively added the green
molecules would be hard to pass through the gaps fluorescein isothiocyanate to DNA strand broken in
between skin cells, but the above effect is achieved by the skin samples. As shown in Fig. 21.4, the fluoresced

503