Photochemically stable, non-leaching, bridged polysilsesquioxane based sunscreens
Bridged polysilsesquioxane based sunscreens prepared as nanoparticles via oil/water microemulsion polymerization, sol-gel polymerizations, or a modified Stober process. Minimized leaching and decreased levels of photo-degradation were achieved with covalent incorporation, with bridged incorporation necessary to ensure isolation of the sunscreen and any photo-products from skin. SPF values of were found to be comparable to existing commercial sunscreens. Furthermore the bridged polysilsesquioxane based sunscreens can be classified as broad-spectrum, and rate from moderate to superior in terms of UVA protective ability.
1. A sunscreen composition comprising one or more monomers of a bridged compound according to Formula I:
wherein A is a UV absorbing moiety, wherein A is selected from a group consisting of salicylate, curcuminoid, benzophenone, acetophenone, and cinnamate monomers,
wherein L 1 is a linker group according to Formula II, III, or IV:
wherein B is a trialkoxysilyl group,
wherein n is at least 2,
wherein L 1 is covalently bonded to A to effectively prevent leeching of A from the sunscreen composition, wherein the multiple trialkoxysilyl groups of the bridged compound monomers are polymerized with tetraalkoxysilane comonomers to form bridged polysilsesquioxane-based sunscreen particles, and wherein the sunscreen composition is resistant to photo-degradation.
2. The sunscreen composition of claim 1 , wherein A comprises at least two functional groups selected from a group consisting of a hydroxyl, an amine, and a carboxylic acid moiety, wherein L 1 is covalently bonded to the functional group.
3. The sunscreen composition according to claim 1 , wherein the trialkoxysilyl group is a triethoxysilyl group or trimethoxysilyl group.
4. The sunscreen composition according to claim 1 , further comprising silicate comonomers in concentrations ranging from 0.001-95 mole %, wherein the silicate comonomers are copolymerized with the bridged compound monomers to form the bridged polysilsesquioxane-based sunscreen particles.
5. The sunscreen composition of claim 4 , wherein the silicate comonomers are selected from a group consisting of tetraalkoxysilane comonomers, sodium silicate comonomers, and organotrialkoxysilane comonomers.
6. The sunscreen composition of claim 5 , wherein the tetraalkoxysilane comonomers are selected from a group consisting of tetramethoxysilane comonomers and tetraethoxysilane comonomers.
7. The sunscreen composition according to claim 1 , wherein each sunscreen particle has a mean diameter of about 50 to 750 nm.
8. The sunscreen composition according to claim 1 , wherein the sunscreen composition is prepared by sol gel polymerization, microemulsion polymerization, or modified Stober polymerization.
9. A sunscreen formulation comprising:
a. the sunscreen composition according to claim 1 , wherein the sunscreen composition is present in an amount effective to absorb UV radiation; and
b. a pharmaceutically-acceptable sunscreen carrier.
10. A sunscreen composition comprising one or more monomers of a bridged compound according to Formula I:
wherein A is a UV absorbing moiety, wherein A is selected from a group consisting of salicylate; curcuminoid, benzophenone, acetophenone, and cinnamate monomers,
wherein L 1 is a linker group according to Formula II, III, or IV:
wherein B is a trialkoxysilyl group,
wherein n is at least 2,
wherein L 1 is covalently bonded to A to effectively prevent leeching of A from the sunscreen composition, wherein the multiple trialkoxysilyl groups of the bridged compound monomers are reacted with tetrafunctional comonomers to form bridged polysilsesquioxane-based sunscreen particles, and wherein the sunscreen composition is resistant to photo-degradation.