Platinum covalent shell cross-linked micelles designed to deliver doxorubicin for synergistic combination cancer therapy

Figures & data

Figure 1 Comparison of gel permeation chromatograms of (A) PCL-Br, (B) PCL-b-P(OEGMA-co-AzPMA) with tetrahydrofuran used as the elute and (C) shell cross-linked micelles with dimethylformamide used as the elute.

Abbreviations: AzPMA, 3-azidopropyl methacrylate; M, molecular weight; M_n, average number molecular weight; OEGMA, oligo(ethylene glycol) ethyl methacrylate; PCL, polycaprolactone; PDI, polydispersity index.

Figure 2 Proton nuclear magnetic resonance spectra of (A) PCL-Br and (B) PCL-b-P(OEGMA-co-AzPMA) in CDCl₃.

Abbreviations: AzPMA, 3-azidopropyl methacrylate; OEGMA, oligo(ethylene glycol) ethyl methacrylate; PCL, polycaprolactone.

Figure 3 Fourier transform infrared spectra of (A) PCL-Br, (B) PCL-b-P(OEGMA-co-AzPMA) and (C) shell cross-linked micelles.

Abbreviations: AzPMA, 3-azidopropyl methacrylate; OEGMA, oligo(ethylene glycol) ethyl methacrylate; PCL, polycaprolactone.

Figure 4 Transmission electron microscopy image of (A) NCL micelles and (B) SCL micelles. Dynamic light scattering curves of NCL and SCL micelles in water (C) and in DMF (D).

Abbreviations: DMF, dimethylformamide; NCL, non-cross-linked; SCL, shell cross-linked.

Figure 5 Thermogravimetric analysis curve of cisplatin, PCL-b-P(OEGMA-co-AzPMA) copolymer and Pt(IV) prodrug-loaded PCL-b-P(OEGMA-co-AzPMA) copolymer.

Abbreviations: AzPMA, 3-azidopropyl methacrylate; OEGMA, oligo(ethylene glycol) ethyl methacrylate; PCL, polycaprolactone; Pt, platinum.

Figure 6 In vitro (A) Pt and (B) DOX release profiles of Pt(IV)- and DOX-loaded shell cross-linked micelles in aqueous solution at (■) pH 7.4, (●) pH 5.5, (▲) pH 7.4 with 5 mM sodium ascorbate and (▼) pH 5.5 with 5 mM sodium ascorbate.

Abbreviations: DOX, doxorubicin; Pt, platinum.

Figure 7 Fluorescence microscopy images of HeLa cells after incubation with DOX- and Pt(IV)-loaded shell cross-linked micelles for 6 h: (A) DOX (red), (B) cell nuclei stained by 4′,6-diamidino-2-phenylindole (blue), (C) bright field and (D) overlay of (A–C).

Abbreviations: DOX, doxorubicin; Pt, platinum.

Figure 8 Cell cytotoxicity of PCL-b-P(OEGMA-co-AzPMA) against A357, HeLa and HEK-293 cells with different incubation times of (A) 48 and (B) 72 h.

Abbreviations: AzPMA, 3-azidopropyl methacrylate; OEGMA, oligo(ethylene glycol) ethyl methacrylate; PCL, polycaprolactone.

Table 1 IC₅₀ values of single drugs and shell cross-linked micelles loaded with DOX and Pt(IV) corresponding to A357 and HeLa cells at different incubation times

Incubation time	Cells	IC50 (µM)
		Free Pt	Free DOX	Pt(IV)-loaded micelles	DOX-loaded micelles	DOX- and Pt(IV)-loaded micelles
48 h	A357	7.19	0.24	8.46	0.81	0.08
72 h	A357	5.37	0.13	7.19	0.14	0.02
48 h	HeLa	2.16	0.50	2.33	1.09	0.24
72 h	HeLa	0.41	0.21	0.93	0.25	0.09

Abbreviations: DOX, doxorubicin; Pt, platinum.

Figure 9 In vitro cell viability of A357 and HeLa cells against single drugs and shell cross-linked micelles loaded with DOX and Pt(IV) at different concentrations and incubation times. *P<0.05 compared with diblock-DOX-Pt.

Abbreviations: DOX, doxorubicin; Pt, platinum.

Scheme 1 Synthesis routes employed for the preparation of dual-drug-loaded shell cross-linked micelles.

Abbreviations: AzPMA, 3-azidopropyl methacrylate; DOX, doxorubicin; OEGMA, oligo(ethylene glycol) ethyl methacrylate; PMDETA, N,N,N′,N″,N′″-pentamethyldiethylenetriamine; Pt, platinum; TEA, triethyl alcohol; TOL, toluene.

Figure S1 ¹H NMR spectra of Pt(IV) containing difunctional alkyne.

Abbreviation: ¹H NMR, proton nuclear magnetic resonance.