142 JOURNAL OF COSMETIC SCIENCE
The structure of the nanocarriers has also been shown to influence penetration through
the skin. Semisolid formulations containing nanocapsules provided greater retention in
the stratum corneum compared to semisolids containing benzophenone-3 in.the free
form.21 Gels containing oxybenzone nanoencapsulated in solid-lipid nanoparticles, and
confocal microscopy was used to assess the localization of the formulations on the skin.
The authors demonstrated that there was a reduction in the penetration of sunscreen
when nanoencapsulated.22 Cutaneous retentions of AVB entrapped in cyclodextrin was
investigated. In their work, the authors demonstrated that the stratum corneum contained
most of the absorbed UV filter.45,46 The proportion of the applied dose that was diffused
into the stratum corneum for the sunscreen cream with nonencapsulated sunscreen agents
was about 30.3% for AVB. The cream with microencapsulated UV filters reduced in vivo
skin penetration by a statistically significant amount. In the deeper stratum corneum layers,
the lipid microparticles inhibitory effect on permeability was more pronounced (45–56.3%
decrease).39
Together, the results show the advantages of encapsulating AVB in NLCs. In the pathway to
incorporating AVB-NLCs in a cosmetic base to develop a commercially available product,
the AVB release, stability of the nanocarriers once incorporated in a cosmetic base stability,
long-term stability of the formulation, and scaling-up should be investigated.
CONCLUSION
Based on the results of the active and excipient interaction studies using DTA and TG/DTG
and FTIR, it was possible to rationally select the components for the preparation of NLCs.
Carnauba wax, isopropyl myristate, Span 85, and Tween 80 were tested for the preparation
of NLCs and encapsulation of AVB. NLCs prepared with carnauba wax showed less loss of
active content in the face of exposure to UVA radiation (maximum 5%, compared to 50% of
loss of AVB in ACN) and greater retention on the skin surface, when compared to the AVB
that penetrated the stratum corneum. These results demonstrate that the incorporation of
this type of active in lipid nanoparticles can contribute both to improve the efficiency of
sunscreen activity and to reduce the permeation of these molecules in the skin.
Figure 8. Amount of AVB-NLC (F3) retained in the cutaneous surface and permeated through the skin
after 24h of the experiment. The pig ear skin model was used in Franz-type static flow cells. Medium was
maintained at 300 rpm, 37°C. The diffusion area was 1.86 cm2. The receiving compartment contained PBS
buffer solution (pH: 7.4) with 5% Tween 20, with 1 mL samples being collected at each time point.
The structure of the nanocarriers has also been shown to influence penetration through
the skin. Semisolid formulations containing nanocapsules provided greater retention in
the stratum corneum compared to semisolids containing benzophenone-3 in.the free
form.21 Gels containing oxybenzone nanoencapsulated in solid-lipid nanoparticles, and
confocal microscopy was used to assess the localization of the formulations on the skin.
The authors demonstrated that there was a reduction in the penetration of sunscreen
when nanoencapsulated.22 Cutaneous retentions of AVB entrapped in cyclodextrin was
investigated. In their work, the authors demonstrated that the stratum corneum contained
most of the absorbed UV filter.45,46 The proportion of the applied dose that was diffused
into the stratum corneum for the sunscreen cream with nonencapsulated sunscreen agents
was about 30.3% for AVB. The cream with microencapsulated UV filters reduced in vivo
skin penetration by a statistically significant amount. In the deeper stratum corneum layers,
the lipid microparticles inhibitory effect on permeability was more pronounced (45–56.3%
decrease).39
Together, the results show the advantages of encapsulating AVB in NLCs. In the pathway to
incorporating AVB-NLCs in a cosmetic base to develop a commercially available product,
the AVB release, stability of the nanocarriers once incorporated in a cosmetic base stability,
long-term stability of the formulation, and scaling-up should be investigated.
CONCLUSION
Based on the results of the active and excipient interaction studies using DTA and TG/DTG
and FTIR, it was possible to rationally select the components for the preparation of NLCs.
Carnauba wax, isopropyl myristate, Span 85, and Tween 80 were tested for the preparation
of NLCs and encapsulation of AVB. NLCs prepared with carnauba wax showed less loss of
active content in the face of exposure to UVA radiation (maximum 5%, compared to 50% of
loss of AVB in ACN) and greater retention on the skin surface, when compared to the AVB
that penetrated the stratum corneum. These results demonstrate that the incorporation of
this type of active in lipid nanoparticles can contribute both to improve the efficiency of
sunscreen activity and to reduce the permeation of these molecules in the skin.
Figure 8. Amount of AVB-NLC (F3) retained in the cutaneous surface and permeated through the skin
after 24h of the experiment. The pig ear skin model was used in Franz-type static flow cells. Medium was
maintained at 300 rpm, 37°C. The diffusion area was 1.86 cm2. The receiving compartment contained PBS
buffer solution (pH: 7.4) with 5% Tween 20, with 1 mL samples being collected at each time point.
