A topically administrable composition comprises an aqueous suspension (e.g. a quick-drying aqueous solution), said aqueous suspension having disposed there within amphiphilic micro-particles having diameters in the range of 1-100 μm, wherein said aqueous suspension comprises: A. hydrophobic nanoparticles of modified metal oxide and/or modified silicon oxide having diameters in the range of 1-150 nm; B. hydrophilic nanoparticles of metal oxide and/or silicon oxide having diameters in the range of 1-150 nm; and C. gas bubbles which are bounded by an internal layer of said hydrophobic nanoparticles and an external layer of said hydrophilic nanoparticles. In some embodiments, the gas-bubbles are air-bubbles.