Figure 2: Time- and frequency-dependent capacitance values for amine modified polystyrene nanoparticles.
From: Real-time and label-free monitoring of nanoparticle cellular uptake using capacitance-based assays
(a) Time-dependent normalized capacitance values, C/Co, where Co is the initial capacitance for HUVEC uptake of different concentrations (107, 108, and 109 PNPs/well) of amine-modified PNPs. The NPs were treated at 23 hour of incubation (gray arrow). After the initial measurement at 100 Hz, the capacitance was measured at various frequencies from 100 Hz to 20 kHz. The capacitance readings were fitted to the relationship C ∝ f−α and C ∝ f−β in the frequency range of 100 Hz to 1 kHz and of 15 kHz to 20 kHz, respectively. (b,c) Time-dependent estimates of |α| (b) and |β| (c) from real-time capacitance measurements using a capacitance sensor array (n = 5). (d) Time-dependent normalized capacitance values, C/Co, where Co is the initial capacitance for HUVECs pretreated with chlorpromazine and cytochalasin D at 23 hour (violet arrow), 1 hour before treatment with NPs (gray arrow). After the initial measurement at 100 Hz, capacitance was measured at various frequencies from 100 Hz to 20 kHz. Time-dependent estimates of α (e) and β (f) from real-time capacitance measurements using a capacitance sensor array (n = 5). Full data are presented in Supplementary Fig. 2.
