Chlorotoxin-functionalized mesoporous silica nanoparticles for pH-responsive paclitaxel delivery to Glioblastoma multiforme

Abstract

Glioblastoma multiforme (GBM) is a highly aggressive brain cancer associated with poor survival rates. We developed novel mesoporous silica nanoparticles (MSNs)-based nanocarriers for pH-responsive delivery of a therapeutic drug Paclitaxel (PTX) to GBM tumor cells. The pores of MSNs are loaded with PTX, which is retained by β-cyclodextrin (CD) moieties covalently linked to the pore entrances through a hydrazone linkage, which is cleavable in weakly acidic environment. Furthermore, we utilized a host-guest interaction between the adamantane and capping CD moieties to further functionalize the surface with a potential glioma-targeting oligopeptide chlorotoxin (CHX). In vitro studies in the U87 GBM cell line show decreased uptake, but increased toxicity of CHX-modified nanoparticles compared to CHX-free nanoparticles. The obtained results are promising toward development of advanced drug nanocarriers, which may target the overexpressed receptors in cancer tissues and utilize their weakly acidic environment for triggering the drug release, potentially leading to more efficient cancer treatments.

Keywords: Chlorotoxin; Cyclodextrin; Glioblastoma multiforme; Mesoporous silica nanoparticles; Paclitaxel; Targeted drug delivery; pH-responsive.

Graphical abstract

Scheme 1

a) Formation of N-β-maleimidopropionic acid hydrazide-mercaptopropyl MSN (BMPH-MPMSN). b) Loading of anticancer drug paclitaxel (PTX) and pore capping with β-cyclodextrin monoaldehyde (CD-CHO). c) Loading of PTX, pore capping with CD-CHO and attachment of chlorotoxin (CHX).

Fig. 1

a) SEM image of PTX@BMPH-MPMSN, b) SEM image of CHX-PTX@BMPH-MPMSN, c) nitrogen sorption isotherms (inset shows BJH pore size distribution) and d) FTIR spectra of PTX@BMPH-MPMSN and CHX-PTX@BMPH-MPMSN. The results for the newly constructed materials are compared to the characteristics of the starting MPMSN and BMPH-MPMSN, which are reproduced with permission from Ref. [34].

Fig. 2

a) Release portion of the loaded PTX and b) the amount of released PTX/g of loaded material, at pH 5 and pH 7.4 from PTX@BMPH-MPMSN and CHX-PTX@BMPH-MPMSN; c) Normalized release kinetics of CHX-PTX@BMPH-MPMSN and PTX@BMPH-MPMSN at pH 5.0 (∗p < 0.05, ∗∗p < 0.01).

Fig. 3

a) Representative confocal microscopy images of U87 cells after 2, 4 or 6 h of incubation with 50 μg/mL of FITC-BMPH-MPMSN, CD-FITC-BMPH-MPMSN or CHX-CD-FITC-BMPH-MPMSN. Cell nuclei are stained with Hoechst 33258 (blue) and cellular membrane with ActinRed™ 555 ReadyProbes™ Reagent (red). NPs are labeled with FITC (green). Scale bar = 100 μm. b) Cell-associated fluorescence over time of U87 cells treated with 50 μg/mL of FITC-BMPH-MPMSN, CD-FITC-BMPH-MPMSN or CHX-CD-FITC-BMPH-MPMSN, expressed as mean ± SD (n = 2). Two-way ANOVA and Sidak's multiple comparisons test were applied (p < 0.05).

Fig. 4

U87 cells viability after the incubation with different concentrations of FITC-BMPH-MPMSN, PTX@BMPH-MPMSN or CHX-PTX@BMPH-MPMSN for a) 24 h, b) 48 h and c) 72 h. Cell viability was analyzed by measuring absorbance at 450 nm with the CCK-8 reagent. Data are expressed as mean ± SD. Two-way ANOVA and Sidak's multiple comparisons test were applied (∗p < 0.05 vs control, ^#p < 0.05).