Reduction-Responsive Docetaxel Prodrug Encapsulated within Human Serum Albumin Nanoparticles for Cancer Therapy

Docetaxel (DTX), a semisynthetic analogue of paclitaxel, is often used to treat cancers. Owing to its poor aqueous solubility, the current formulation of DTX for clinical applications involves using high surfactant and ethanol concentrations, causing hypersensitivity reactions. To overcome this issue, we developed a reduction-responsive DTX prodrug encapsulated within human serum albumin (HSA) nanoparticles (DTX-SS-COOH/HSA NPs). First, the DTX prodrug was conjugated to undecanoic acid through a disulfide bond (DTX-SS-COOH) via a four-step reaction. Subsequently, DTX-SS-COOH/HSA NPs were prepared via the desolvation method. The NPs exhibited a spherical structure with a diameter range of 140-220 nm, as revealed by dynamic light scattering and transmission electron microscopy. Fluorescence quenching analysis confirmed the formation of DTX-SS-COOH/HSA, which was ascribed to electrostatic interactions and hydrophobic forces. Notably, NPs with a feed mole ratio corresponding to DTX-SS-COOH/HSA = 9:1 demonstrated high drug-loading and encapsulation efficiency of 12.84 and 93.11%, respectively, alongside good stability. Moreover, the reduced responsiveness experiment revealed an accelerated DTX release in the presence of glutathione. An in vivo pharmacokinetic study indicated that DTX-SS-COOH/HSA NPs demonstrated considerably a prolonged circulation time (6.2-fold) compared to that of free DTX. Ultimately, the antitumor test of MDA-MB-231 tumor-bearing mice revealed that DTX-SS-COOH/HSA NPs were superior to DTX/HSA NPs for tumor growth inhibition. Thus, DTX-SS-COOH/HSA NPs represent a promising DTX nanoformulation for clinical application.