Enhancing Tumor Accumulation and Cellular Uptake of Layered Double Hydroxide Nanoparticles by Coating/Detaching pH-Triggered Charge-Convertible Polymers

[Image: see text] Layered double hydroxide (LDH) nanoparticles are extensively explored as multifunctional nanocarriers due to their versatility in both the host layer and the interlayer anion. In this study, we report modification of positively charged Cu-containing LDH nanoparticles with a pH-responsive charge-changeable polymer to improve the particle colloidal stability in blood circulation, reduce the nonspecific uptake by normal cells in organs, and subsequently facilitate tumor accumulation and uptake by tumor cells in the acidic tumor microenvironment. In vitro experimental results demonstrate that this promising charge-convertible polymer–LDH nanocarrier well reduces the capture by macrophages in the physiologic medium (pH 7.4) but facilitates the uptake by tumor cells due to detaching of the coated polymer layer in the weakly acidic condition (pH 6.8). Cu-containing LDH nanoparticles also show pH-responsive magnetic resonance imaging (MRI) contrast capacity (i.e., r(1) relaxivity). In vivo MRI further confirms effective tumor accumulation of the charge-convertible nanohybrids, with ∼4.8% of the injected dose accumulated at 24 h postintravenous injection, proving the potential as a versatile delivery nanocarrier to enhance the antitumor treatment.