PEGylation of lipophilic SN38 prodrug with DSPE-mPEG₂₀₀₀ versus cremophor EL: comparative study for intravenous chemotherapy

Figures & data

Figure 1. Preparation and characterization (TEM image, zeta potential, size distribution and PDI) of DSPE-mPEG₂₀₀₀/NPs (A) and Cremophor EL/NPs (B). Fluorescence emission spectra (C) and UV-vis spectra (D) of the DSPE-mPEG₂₀₀₀/NPs, Cremophor EL/NPs and ethanol solution of SN38 prodrug (monomeric species) at the SN38 equivalent concentration of 10 µg/ml.

Table 1. Effects of added amount of lipophilic PEG derivatives on particles size (zeta potential) of DSPE-mPEG₂₀₀₀/NPs and Cremophor EL/NPs.

Prodrug/Stabilizer (w/w)	Cremophor EL/NPs			DSPE-mPEG2000/NPs
	Size (nm)	PDI	Zeta potential (mV)	Size (nm)	PDI	Zeta potential (mV)
1:17.5	15.02	0.148	1.97	178.5	0.245	−34.1
1:1.75	80.46	0.205	−7.61	104.2	0.274	−23.5
1:0.1	121.2	0.143	−15.6	137.2	0.164	−23.7

Figure 2. Change of particle size of DSPE-mPEG₂₀₀₀/NPs and Cremophor EL/NPs in water stored at 4 °C for 4 weeks, [means ± SD, n = 3] (A). Schematic illustration of the mechanism to detect prodrug exchange between NPs using a FRET technique, the lipophilic prodrugs of SN38 and Cur were chosen as the FRET donor and acceptor, respectively (B). Kinetic change of fluorescence intensity of SN38 when SN38 prodrug-loaded NPs were mixed with that containing Cur prodrug (C).

Figure 3. Comparative studies on Cremophor EL/NPs and DSPE-mPEG₂₀₀₀/NPs: Confocal laser scanning microscopy images of CT26 cells cultured with NPs at the SN38 equivalent concentration of 10 μg/ml for 2 h (A). HPLC analysis of the released SN38 and prodrug within the CT26 cells cultured with NPs at 10 μg/ml for 4 h [mean ± SD, n = 4], **p < .01 (B). Cytotoxicity study against the CT26 determined by the MTT assay (C). SN38 release from Cremophor EL/NPs and DSPE-mPEG₂₀₀₀/NPs in the culture medium (D). Apoptotic analysis of CT26 cells by FACS using an Alexa Fluor 488 Annexin V/PI Detection Kit after 48 h of NPs incubation at 5 μg/ml (E).

Figure 4. Plasma concentration–time profiles in rat following a single intravenous administration at the SN38 equivalent dose of 5 mg/kg, [mean ± SD, n = 4] (A). Tumor picture (B), tumor burden (C) and mice body weight (D) after last treatment against subcutaneous CT26 tumor in BALB/C mice at the equivalent SN38 dose of 5 × 10 mg/kg/2 day, [mean ± SD, n = 7], *p <.001, ***p < .001.