Hepatocyte-Targeting Single Galactose-Appended Naphthalimide: A Tool for Intracellular Thiol Imaging in Vivo

Abstract

We present the design, synthesis, spectroscopic properties, and biological evaluation of a single galactose-appended naphthalimide (1). Probe 1 is a multifunctional molecule that incorporates a thiol-specific cleavable disulfide bond, a masked phthalamide fluorophore, and a single galactose moiety as a hepatocyte-targeting unit. It constitutes a new type of targetable ligand for hepatic thiol imaging in living cells and animals. Confocal microscopic imaging experiments reveal that 1, but not the galactose-free control system 2, is preferentially taken up by HepG2 cells through galactose-targeted, ASGP-R-mediated endocytosis. Probe 1 displays a fluorescence emission feature at 540 nm that is induced by exposure to free endogenous thiols, most notably GSH. The liver-specificity of 1 was confirmed in vivo via use of a rat model. The potential utility of this probe in indicating pathogenic states and as a possible screening tool for agents that can manipulate oxidative stress was demonstrated in experiments wherein palmitate was used to induce lipotoxicity in HepG2 cells.

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

“…Particle size and Z-potential measurements were conducted by diffuse light scattering (DLS), using a Zetasizer Nano ZS (Malvern Instruments Ltd., Worcestershire, United Kingdom). Dried materials were re-suspended in deionized water at a concentration of 5 mg mL 21 and DLS measurements were performed at 25 uC and 173u scattering angle. The mean hydrodynamic diameter was determined by cumulant analysis.…”

“…While prodrugs of CPT with cleavable disulfide linkers that release the unaltered drug have been developed, no information was available on its direct attachment to a nanoparticulated transporter. [21][22][23][24][25] We therefore performed a singular synthetic strategy based on the direct incorporation of CPT prodrugs on the nanocarrier. For this purpose, we first synthesized novel (pyridin-2-yldisulfanyl)alkyl carbonate derivatives of CPT, according to Scheme 1 (compounds 4a-c).…”

“…Here, while some authors point out the role of GSH for disulfide cleavage and cytosolic release, 8,9,17,[21][22][23][24][25][43][44][45][46] the endosomal/lysosomal reducing activity mediated by PDI 43 or endosomal reductase, 47 could also bring an early download of the therapeutic molecule. In addition, it must be taken into account that carbonate bonds could also be cleaved by unspecific cytosolic carboxylases.…”

“…After 72 h, MTT solution in PBS was added at a final concentration of 0.2 mg mL 21 to the wells and 4 h later formazan crystals were dissolved in DMSO and spectrophotometrically measured at 550 nm (Perkin-Elmer VictorX5 Microplate Reader). IC 50 calculation survival data were evaluated by variable slope curve-fitting using Prism 5.0 software (GraphPad, San Diego, CA).…”

Fluorescent Dyes Used in Polymer Carriers as Imaging Agents in Anticancer Therapy

“…Kim et al [122] described a tool embedded with a single galactose subunit (which guides the probe to hepatocytes) and a disulfide-linked 4-amino-1,8-naphthalimide moiety. The probe provides an easy-tomonitor fluorescent change when exposed to endogenous thiols as the result of disulfide cleavage.…”