A physical model for the size-dependent cellular uptake of nanoparticles modified with cationic surfactants

Figures & data

Table 1 Physicochemical properties of nanoparticles (n = 3)

Sample	Particle size (nm)	Polydispersity index	Zeta potential (mv)	Entrapment efficiency (%)
1a	237.5 ± 1.08	0.126	−1.4	30 ± 4.2
2b	56.2 ± 5.7	0.157	55.6	41 ± 3.1
3	103.6 ± 9.2	0.116	57.1	46 ± 2.3
4	147.0 ± 8.4	0.139	57.5	45 ± 2.9
5	197.5 ± 9.2	0.153	60.1	47 ± 2.1
6	305.6 ± 23.5	0.158	59.0	52 ± 2.3

Notes:

a Sample 1 was prepared with 5% PVA;

b samples 2–6 were prepared with 0.5% DMAB.

Data are represented as mean ± standard deviation.

Abbreviations: PVA, poly vinyl alcohol; DMAB, didodecyl dimethylammonium bromide.

Figure 1 TEM micrograph of DMAB-modified PLGA nanoparticles with different average sizes: (A) 50 nm; (B) 100 nm; (C) 150 nm; (D) 200 nm; and (E) 300 nm.

Abbreviations: TEM, transmission electron microscopy; DMAB, didodecyl dimethylammonium bromide; PLGA, coumarin-6 loaded poly (lactide-co-glycolide).

Figure 2 Cellular uptake efficiency of PVA-coated nanoparticles and DMAB-coated nanoparticles with different sizes (A). PLGA nanoparticles were incubated in Caco-2 cells (gray bars) and HT-29 cells (black bars) for 4 hours at a concentration of 500 μg/mL, at 37°C; the uptake rate is given as a function of the size of the nanoparticle (B).

Note: The calculated curve (red and blue solid lines) agreed well with the experimental data (red squares and blue circles, respectively).

Abbreviations: PVA, poly vinyl alcohol; DMAB, didodecyl dimethylammonium bromide; PLGA, coumarin-6 loaded poly (lactide-co-glycolide).

Figure 3 Schematic view of a nanoparticle adhering to a cell.

Abbreviations: R₀, original radius of the cell; R, radius of the deformed cell; z, an index by which to estimate the percentage of the particles taken by the cell.

Figure 4 Schematic view of the interaction between nanoparticles and cells.

Note: The Deserno’s model showed that the uptake of the nanoparticles occurred as a result of the competition between the bending energy and the stretching energy.

Figure 5 Confocal microscopic images of (A) Caco-2 cells and (B) HT-29 cells incubating with DMAB-modified C6-loaded nanoparticles of (a) 100 nm and (c) 50 nm for 4 hours at the concentration of 500 μg/mL, at 37°C. The close-ups of entrapped fluorescent nanoparticles (green) could be observed directly in the right panels [(b) and (d)].

Note: Scale bars = 20 μm.

Abbreviations: DMAB, didodecyl dimethylammonium bromide; C6, coumarin-6.