Fig. 3From: Stem cell membrane-coated isotretinoin for acne treatmentSkin irritation by STCM-ATRA-NPs. Skin application of a PBS, b STCM, c ATRA, or d STCM-ATRA-NPs for 6 h. e Criteria of skin irritation. Data shown are mean ± S.D., n = 3Back to article page