Fig. 4. US-induced release of CPT from P₁ (11.6 μM, 3 mg mL⁻¹ in MeCN : H₂O = 2 : 3 (v/v)) for MTS proliferation assays. (a) Control MTS proliferation assays of NAP, CPT, 1, P₁, and pristine POEGMEA. (b) MTS proliferation assay of P₁ with progressing ex situ sonication. Assay of pure CPT is shown again for comparison. Mean values ± SD from the mean, N = 3 independent experiments.