Page 530 - Book Hosokawa Nanoparticle Technology Handbook

APPLICATIONS 21 DEVELOPMENT OF FUNCTIONAL SKINCARE COSMETICS

VC-IP PLGA NS
Penetration of PLGA NS
to Stratum basale epidermidis Corneum
via Corneum

1 Hydrolysis of PLGA NS
2 Slow release of VC-IP
3 Change VC-IP to L-ascorbic acid
(VC) by esterase
VC
Physiological function as
L-ascorbic acid Antioxidation
In Melanocyte Inhibition of cytotoxic of keratinocyte
Inhibition of melanin generation (epidermic cell) and fibroblast
•Inhibition of tyrosinase activity by UV
•Reduction of melanin intermediate, dopa quinone Sustentation of immune
(Tyrosin ⇒ dopa ⇒ dopa quinon ⇒ melanin)
•Reduced shade of melanin response to lymph cell
(Whitening) Improvement of atopic dermatitis
(Skin Protection)
In Dermis and Fibroblast
Promotion of collagen generation
(Anti-ageing)

Figure 21.1
Vitamin C delivered to deep skin by VC-IP encapsulated PLGA nanospheres and its pharmacological effects.

Fig. 21.2 shows the SEM photographs of skin sam- energy of the dispersion and skin was weakened, and
ples taken over several hours after applying 0.2% the nanospheres acquired enough thigmotaxis in the
aqueous dispersion of coumarin-6 loaded PLGA dispersion to permeate the corneum layer.
nanospheres (0.0001 wt% coumarin-6 concentration,
D 215 nm) in comparison to those applying (2) Effectiveness of the VC-IP encapsulated PLGA
50
coumarin-6 dispersion (10 wt% coumarin-6 concen- nanospheres
tration, D 4.63 m, with 15 wt% of the particles in Vitamin C can prevent oxidation of biological materi-
50
the sub-micrometer range). Coumarin-6 is a fluores- als in the skin caused by the UV irradiation, promote
cent substance and serves as the labeling agent in the the formation of collagen, and suppress the occurrence
experiment. The coumarin-6 loaded PLGA nanos- of melanin pigment. It is known for its effectiveness in
pheres permeated the skin far better and sustained preventing spots, wrinkles and aging of skin, and is
much longer in the tissue than the coumarin-6 solu- often used in the skincare products. But, vitamin C is
tion. The coumarin-6 loaded nanospheres could reach very unstable and can easily be decomposed under
the dermis by passing through the skin pores. In addi- ordinary conditions. In addition, it has very poor skin
tion, the concentration of coumarin-6 in the PLGA permeability due to its hydrophilic characteristics. In
nanospheres suspension was 1/100,000th of that of this study, taking the advantage of their superb skin
coumarin-6 solution used in the experiment. The permeability, PLGA nanospheres were used as the car-
intense image of the highly diluted coumarin-6 loaded riers to deliver vitamin C to the epidermis and dermis.
PLGA nanospheres permeating through the skin fur- The vitamin C used in the experiment was an oil-
ther demonstrated the effectiveness of drug loaded soluble vitamin C derivative, “ascorbyl tetraisoplami-
PLGA nanospheres for transdermal drug delivery tate (VC-IP)”. The esterase in the skin transformed
applications. Also, although not shown here, a sepa- VC-IP to reduced vitamin C (ascorbic acid), known as
rate skin sample evaluation showed that the coumarin-6 an antioxidant.
loaded PLGA nanospheres could effectively permeate After the skin samples were treated for a certain
the skin in places without skin pores. period of time, the epidermis and dermis were sepa-
This effect is attributed to two factors. First, some rated, and the contained amounts of vitamin C in each
of the PLGA nanospheres were small enough to skin layer were measured with HPLC and coulomet-
directly slip through the gaps between the skin cells in ric ECD. Applying the conventional VC-IP aqueous
the corneum layer; and secondly, the interfacial dispersion (emulsion), only small amounts of the

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