Glutathione-sensitive nanoplatform for monitored intracellular delivery and controlled release of Camptothecin

Abstract

We report the design, synthesis, characterization and in vitro testing of a novel nanodrug based on a covalent linking model that allows intracellular controlled release of the pharmaceutical payload. A new synthetic strategy is implemented by direct coupling of as-synthesized (pyridin-2-yldisulfanyl)alkyl carbonate derivatives of camptothecin (CPT) with thiol groups of silica hybrid nanoparticles containing a non-porous core and a mesoporous shell. Upon reaction with thiols in physiological conditions, disulfide bridge cleavage occurs, releasing the naked drug after an intramolecular cyclization mechanism.Additional incorporation of a fluorophore into particles core facilitates imaging at the subcellular level for the monitoring of uptake and delivery. Confocal microscopy experiments in HeLa cervix cancer cells confirms that nanoparticles enter the cells by endocytosis but are able to escape from endo-lysosomes and enter the cytosolic compartment to release their cargo. The incorporation to cells of L-buthioninesulfoximine, a glutathione inhibitor allows concluding that the intracellular releasing mechanism is mainly driven by the reducing activity of this tripeptide. This camptothecin nanoplatform shows the same cytotoxic activity than the free drug and is clearly superior to those release systems depending on enzymatic hydrolysis (as determined by calculation of the IC 50 ratios).

Safe approaches for camptothecin delivery: Structural analogues and nanomedicines

“…Also recently, our group implemented a new synthetic strategy by direct coupling of assynthesized (pyridin-2-yldisulfanyl)alkyl carbonate derivatives of CPT with thiol groups of silica hybrid nanoparticles containing a non-porous core and a mesoporous shell [173].…”

“…Upon reaction with thiols in physiological conditions, disulfide bridge cleavage occurs, releasing the naked drug after an intramolecular cyclization mechanism. (Adapted from ref 173,. with permission of The Royal Society of Chemistry)A supramolecular strategy was reported to directly assemble the hydrophobic CPT molecule to a β-sheet-forming peptide sequence derived from the cysteine-containing au protein through the reducible disulfylbutyrate (buSS) linker, obtaining discrete, stable, well-defined nanostructures with a high and quantitative drug loading[175].…”

Dual-channel NIR activatable theranostic prodrug for in vivo spatiotemporal tracking thiol-triggered chemotherapy

“…On the other hand, the cells treated by Cy-C-CPT either with or without GSH showed very rare CyA-K florescence, suggesting that most prodrugs were still in the intact status, and the disulfide linkage was indeed critical for prodrug activation. 24 …”

Glycyrrhetinic Acid-Functionalized Mesoporous Silica Nanoparticles for the Co-Delivery of DOX/CPT-PEG for Targeting HepG2 Cells

“…The result crude was purified through a silica gel column chromatographic with hexanes:AcOEt mixtures 8:2. The product 4 was collected and the solvent was removed by rotatory evaporation [31]. Yield: (4) 96.9 mg (η = 38%).…”