Evaluation of calix[4]arene vectors efficiency for the delivery of mature miRNA. (A,C) Percentage of fluorescence positive cells in U251 glioma (A) or HT29 colon cancer (C) cell line transfected with a mature miRNA complexed with commercially available, cationic liposomes-based transfection agent, and mature miRNA used alone or delivered by different calix[4]arene vectors. (B,D) Percentage of fluorescence-positive cells obtained comparing three different batches (Arg-Hex A–C) of the same vector, the lead compound Arg-Hex, obtained by three different purification strategies. Results are resented as mean ± S.E.M; statistical differences between groups were compared using a one-way repeated measures ANOVA. * p < 0.05, ** p < 0.01.