The effect of drug position on the properties of paclitaxel-conjugated gold nanoparticles for liver tumor treatment

Abstract

Structure-efficacy effect of small molecular drug attracts wide attentions, but it has always been ignored in nanomedicine research. To reveal the efficacy modulation of nanomedicine, we developed a new type of paclitaxel (PTX)-conjugated gold nanoparticles (PTX-conjugated GNPs) to investigate the influence of drug position in controlling their in vitro properties and in vivo performance. Two therapeutic ligands (TA-PEG-NH-N=PTX and TA-PTX=N-NH-PEG) were synthesized to conjugate PTX on the surface of GNPs at different positions, locating on the surface of gold conjugate and inserting between GNPs and polyethylene glycol (PEG, molecular weight 1000 Da), respectively. It was found that PEG-PTX@GNPs with PTX located between GNP and PEG exhibited higher aqueous solubility, biocompatibility, and stability. In addition, an acid sensitive hydrazone bond has been inserted between PTX and PEG in both ligands for drug release of PTX and PTX-PEG segment, respectively, at the tumor site. Further release of PTX from PTX-PEG segment is based on the esterase hydrolysis of an ester bond between PTX and PEG. This two-step drug release mechanism offers PEG-PTX@GNPs effective and sustained release behavior for desirable anticancer activity, enhanced therapeutic efficacy, and lower systematic toxicity in Heps-bearing animal models.