Fig. 1 Hydrophilic outside mirror (right).

which the glass is also bent simultaneously withthe film baking operation to obtain the desiredoutside mirror shape.

The hydrophilic outside mirror developed in thiswork (Fig. 1) maintains its hydrophilic propertyover a long period of time because it is coated

with a TiO2-SiO2 mixture to which a colloidaltype of SiO2 (2) has been added to improvehydrophilicity.

Reference

1. M. Anpo, et al., Surface 29 (No. 2), 156 (1991) (inJapanese).

Advanced Sunscreens: UV Absorbers Entrappedin Sol-Gel Glass Microcapsules

Claudio Rottman, Orit Gans, Fabio Biagini and Noa LapidotSol-Gel Technologies Ltd.http://www.sol-gel.com

Sol-Gel Technologies (SGT) has developed aprocess for the production of microencapsulatedsunscreen active ingredients for human applica-tion [1]. The obtained active ingredients consistof a core of the UV abosorber entrapped withina sol-gel silica shell. The UV abosorber, whichis usually an oil or oil soluble compound, con-stitutes about 80% of the capsule weight. Theseadvanced sunscreen actives are incorporated intoa suitable cosmetic vehicle to achieve high

For further information, contact Nir Zalmanov, Product Development Manager, Sol-Gel Technologies Ltd., POB 367 Bet Shemesh99100, Israel; e-mail nir.zalmanov@sol-gel.com.

Sun Protection Factors (SPF), while affordingimproved safety profile, as the penetration of theUV abosorbers is markedly reduced.

Currently, sunscreen actives are included in vir-tualy all types of cosmetic products for daily use.Specifically in sunscreen products, the manu-tactureres have to use a mixture of severalUV abosorbers in order to achieve the desiredUV protection (high protection factors for both

Fig. 1(A) Typical SEM picture of the sol-gel encapsulated sunscreen particles;(B) Enlargement of a single broken particle, showing the silica shell, which is

hollow after the oil was washed away during sample preparation.

UVB and UVA), while remaining within the sin-gle molecule limits allowed by the regulatingauthotrities. The concentration of UV abosor-bers in a formulation often reaches about 30%of the composition. The active molecule com-binations often lead to formulation difficultiesand to cross-reactions, which may induce photo-

decomposition and adverse effects such as aller-gies and photo-allergies.

The products are obtained as an aqueous disper-sion, containing 35% wt. UV absorber(s). Thecapsules are about 1 micron in diameter (Fig. 1),thus they are sufficiently small to be transparent

Fig. 2 Skin penetration experiment: Octyl Methoxycinnamte (OMC) penetration through model Taffryn� membrane.�, Suncreem containing free OMC; �, Suncreem containing encapsulated OMC.

on the skin and to give a pleasant feel. The silicamicrocapsules were shown to effectively retainthe encapsulated UV absorbers in a series of ex-traction experiments.

Skin penetration experiments show (Fig. 2)markedly reduced penetration or retention ofsunscreen actives in the skin. Separate encapsu-lation of incompatible UV abosorbers, that areknown to photodegrade when present together inthe same formulation, affords improved photo-stability of these ingredients.

The encapsulated sunscreens obtained throughthe sol-gel technology offer improved productsthat maintain the high SPF’s required, while el-liminating contact between the actives and body

tissues. Encapsulation in sol-gel glass can also beused to separate incompatible compounds withinthe same formulation. This encapsulation tech-nology is flaxible and may be used in furtherapplications.

Encapsulated sunscreen ingredients are pro-duced on industrial scale at the purposely builtplant in Israel. SGT is investing in research anddevelopment of further cosmetic and pharmaceu-tical products.

Reference

1. C. Rottman, O. Gans, and N. Lapidot, Euro Cosmetics,Jan. 2000.