Design of theranostic nanomedicine (II): synthesis and physicochemical properties of a biocompatible polyphosphazene–docetaxel conjugate

Figures & data

Figure 1 Reaction scheme for synthesis of the drug carrier polymer (I), DTX precursor (II), and conjugate drug, Polytaxel (III).

Note: The numbers in parentheses are the identification numbers for compounds.

Abbreviations: AA, aconitic acid; Boc, tert-Butoxycarbonyl; DIC, diisoproplycarbodiimide; DIPEA, N-ethyldiisoproplyamine; DPTS, 4-(dimethylamino)pyridine 4-toluenesulfonate; DTX, docetaxel; Et₃N, triethyl amine; Lys, lysine; MPEG, methoxy poly(ethylene glycol); OEt, ethylester; RT, room temperature; TFA, trifluoroacetic acid; THF, tetrahydrofuran.

Figure 2 The particle size distributions of the polyphosphazene carrier polymer [NP(MPEG550)₃(Lys-OEt)]_n (A) and its DTX conjugate Polytaxel (B), as well as the TEM image of Polytaxel in aqueous solution (C) and the CMC value measured by the pyrene fluorescence method (D).

Abbreviations: CMC, critical micelle concentration; DTX, docetaxel; III₃₃₈/_I333, ratio of fluorescence intensities measured at 338 nm and 333 nm; Lys-OEt, lysine ethylester; MPEG, methoxy poly(ethylene glycol); NP, polyphosphazene backbone; TEM, transmission electron microscopy.

Figure 3 Mean plasma concentration–time profiles of docetaxel after intravenous injection of Taxotere^® (●) or Polytaxel (▲) at a dose of 5 mg/kg in rats.

Note: Bars represent the standard deviation (n=5).

Table 1 PK parameters of docetaxel after intravenous injection of Polytaxel and Taxotere^® at a dose of 5 mg/kg in rats

PK parameters	Taxotere	Polytaxel
C0, µg/mL	8.76±3.22	0.244±0.053
AUClast, µg⋅h/mL	0.651±0.098	0.969±0.153
t1/2, h	0.651±0.093	3.53±0.368
Vd, mL	1,758±159	5,931±915
Clt, mL/h	1,896±255	1,168±174

Note: Data presented as mean ± SD.

Abbreviations: AUC_last, area under the plasma concentration–time curve from time zero to the last experimental time point; C₀, initial plasma concentration; Cl_t, total clearance; PK, pharmacokinetic; t_1/2, elimination half-life; V_d, apparent volume of distribution.

Figure 4 Time-dependent organ distribution of Cy-Polytaxel in the A549 tumor bearing mice.

Note: Fluorescence images of major organs and tumor (A) and plasma (B), harvested from the tumor-bearing mice from 12 to 96 h postinjection.

Abbreviation: Cy, cyanine dye.

Figure 5 The quantitative fluorescence intensities of Cy-Polytaxel distributed in each major organ of the A549 tumor-bearing mice (A) and TTR (B).

Note: Bars represent standard deviation (n=3).

Abbreviations: Cy, Cyanine dye; TTR, tumor-to-normal tissue ratio.

Figure 6 Time-dependent amount of docetaxel in major organs and tumor, quantified by LC-MS/MS.

Note: Bars represent standard deviation (n=3).

Abbreviation: LC-MS/MS, liquid chromatography tandem mass spectrometry.

Figure 7 The time-dependent clearance rates of Polytaxel from major organs and tumor after its injection, in terms of fluorescence intensity.

Note: Bars represent standard deviation (n=2).

Figure 8 In vitro release profiles of DTX from Polytaxel in acidic (pH 5.4) and neutral (pH 7.4) buffer solutions at 37°C.

Abbreviation: DTX, docetaxel.

Figure 9 The results of in vivo study of the antitumor efficacy of Taxotere^® and Polytaxel against the gastric tumor cell line MKN-28.

Notes: Polytaxel was injected at doses of 10 and 20 mg/kg based on docetaxel content. Bars represent standard deviation (n=5).

Figure S1 ¹H-NMR spectra of the polyphosphazene carrier polymer [NP(MPEG550)₃(Lys-OEt)]_n (A) and its conjugate, Polytaxel [NP(MPEG550)₃(Lys-OEt)(AA) (DTX)]_n (B).

Abbreviations: AA, aconitic acid; DTX, docetaxel; Lys-OEt, lysine ethylester; MPEG, methoxy poly(ethylene glycol); NMR, nuclear magnetic resonance; NP, polyphosphazene backbone.

Figure S2 ³¹P-NMR spectrum of polyphosphazene carrier polymer [NP(MPEG550)₃(Lys-OEt)]_n (A) and its Polytaxel conjugate [NP(MPEG550)₃(Lys-OEt)(AA)(DTX)]_n (B).

Abbreviations: AA, aconitic acid; DTX, docetaxel; Lys-OEt, lysine ethylester; MPEG, methoxy poly(ethylene glycol); NMR, nuclear magnetic resonance; NP, polyphosphazene backbone.

Figure S3 Conceptual diagram for the self-assembly of Polytaxel into polymeric micelles.

Abbreviations: AA, aconitic acid; DTX, docetaxel; Lys-OEt, lysine ethylester; MPEG, methoxy poly(ethylene glycol); NP, polyphosphazene backbone.

Figure S4 Changes in body weight of nude mice treated with Taxotere^® and Polytaxel.

Note: Bars represent standard deviation (n=5).