pH-sensitive micelles self-assembled from polymer brush (PAE-g-cholesterol)-b-PEG-b-(PAE-g-cholesterol) for anticancer drug delivery and controlled release

Figures & data

Figure 1 Scheme of drug loading and controlled release from triblock polymer brush (PAE-g-Chol)-b-PEG-b-(PAE-g-Chol) dependent on pH values.

Abbreviations: (PAE-g-Chol)-b-PEG-b-(PAE-g-Chol), (poly(β-amino esters)-g-cholesterol)-b-poly(ethylene glycol)-b-(poly(β-amino esters)-g-cholesterol); DOX, dox orubicin; PAE, poly (β-amino esters); PEG, poly(ethylene glycol).

Figure 2 The synthetic route of the polymer (PAE-g-Chol)-b-PEG-b-(PAE-g-Chol).

Abbreviation: (PAE-g-Chol)-b-PEG-b-(PAE-g-Chol), (poly(β-amino esters)-g-cholesterol)-b-poly(ethylene glycol)-b-(poly(β-amino esters)-g-cholesterol).

Figure 3 ¹H NMR spectrum of polymer brush (PAE-g-Chol)-b-PEG-b-(PAE-g-Chol) in d-CDCl₃.

Abbreviation: (PAE-g-Chol)-b-PEG-b-(PAE-g-Chol), (poly(β-amino esters)-g-cholesterol)-b-poly(ethylene glycol)-b-(poly(β-amino esters)-g-cholesterol).

Figure 4 The potentiometric titration of polymer (PAE-g-Chol)-b-PEG-b-(PAE-g-Chol) solutions.

Abbreviation: (PAE-g-Chol)-b-PEG-b-(PAE-g-Chol), (poly(β-amino esters)-g-cholesterol)-b-poly(ethylene glycol)-b-(poly(β-amino esters)-g-cholesterol).

Figure 5 Plot of intensity ratios (I₃₃₇/I₃₃₅) as function of logarithm of the polymer brush concentrations in different PBS buffer solutions (pH 7.4, 6.5, 6.0, and 5.0).

Abbreviation: PBS, phosphate-buffered saline.

Figure 6 Particle size (A) and zeta potential (B) of polymeric micelles dependent on pH values. Typical TEM images (C) of micelles in different solutions with pH 7.4 (left) and 5.0 (right).

Abbreviation: TEM, transmission electron microscopy.

Table 1 Characterization of DOX-loaded (PAE-g-Chol)-b-PEG-b-(PAE-g-Chol) micelles at pH 7.4, T =37°C

Polymer (mg)	DOX (mg)	LC (%)	EE (%)	Particle size (nm)	PDI	Zeta potential (mV)
50	0	–	–	205.4	0.124	12.7
	5	4.2	33.6	218.1	0.152	11.5
	10	13.5	48.7	226.5	0.213	14.8
	25	20.1	59.5	234.7	0.226	18.2
	40	24.3	55.3	247.8	0.230	17.2

Abbreviations: DOX, doxorubicin; LC, load content; EE, entrapment efficiency; PDI, polydispersity index; (PAE-g-Chol)-b-PEG-b-(PAE-g-Chol), (poly(β-amino esters)-g-cholesterol)-b-poly(ethylene glycol)-b-(poly(β-amino esters)-g-cholesterol).

Figure 7 In vitro drug release profiles (A) and mechanism analysis (B) of DOX-loaded (PAE-g-Chol)-b-PEG-b-(PAE-g-Chol) micelles.

Table 2 n and k values for DOX-PMs at pH 7.4, 6.5, 6.0, and 5.0, T =37°C

pH	n (0–12 h)	k (0–12 h)	n (12–120 h)	k (12–120 h)
7.4	0.5655	0.0694	0.1555	0.1806
6.5	0.6131	0.0898	0.1967	0.2407
6.0	0.4869	0.1515	0.1103	0.3877
5.0	0.3277	0.2588	0.0881	0.5342

Abbreviation: DOX-PM, doxorubicin-loaded polymeric micelle.

Figure 8 Cytotoxicity for HepG2 cells treated with polymer brush for 48 h (A) or free DOX or DOX-PMs for 24 h (B) or 48 h (C) in concentration specified.

Abbreviations: DOX, doxorubicin; DOX-PM, doxorubicin-loaded polymeric micelle.