Fig. 6From: Preparation of HCPT-Loaded Nanoneedles with Pointed Ends for Highly Efficient Cancer ChemotherapyDefinition of Φ and the schematic illustration of the internalization of NDs, NRs, and NSs (a–c). \( \overline{M} \) and \( \overline{N} \) are vectors that show the flow directions of the cell membranes. Φ is the angle between \( \overline{M} \) and \( \overline{N} \). d The measurement of the Φ of the NDs. e–f The SEM of the NRs and NSsBack to article page