molecules Article Fractional CO2 Laser Pretreatment Facilitates Transdermal Delivery of Two Vitamin C Derivatives Chien-Yu Hsiao 1,2,3, Hsin-Ching Sung 3,4, Sindy Hu 3,5,6, Yau-Li Huang 3,5,6 and Chun-Hsun Huang 2,3,6,* 1 Department of Nutrition and Health Sciences, Chang Gung ...