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Chirality is one of the ubiquitous phenomena in biological systems. The left handed (L-) amino acids and right handed (D-) sugars are normally found in proteins, and in RNAs and DNAs, respectively. The effect of chiral surfaces at the nanoscale on cellular uptake has, however, not been explored. This study reveals for the first time the molecular chirality on gold nanoparticles (AuNPs) functions as a direct regulator for cellular uptake. Monolayers of 2-mercaptoacetyl-L(D)-valine (L(D)-MAV) and poly(acryloyl-L(D)-valine (L(D)-PAV) chiral molecules were formed on AuNPs surface, respectively. The internalized amount of PAV-AuNPs was several times larger than that of MAV-AuNPs by A549 and HepG2 cells, regardless of the chirality difference. However, the D-PAV-AuNPs were internalized with significantly larger amount than the L-PAV-AuNPs. This chirality-dependent uptake effect is likely attributed to the preferable interaction between the L-phospholipid-based cell membrane and the D-enantiomers.

The interaction between nanoparticles (NPs) and proteins is a topic of high relevance for the medical application of NPs. This study reveals the molecular chirality on NP surfaces as an indirect regulator of the interaction between proteins and NPs. Poly(N-acryloyl-valine) (PAV) polymers with d- and l-configurations were conjugated onto gold NPs with a size of 5 nm to obtain the l-PAV-AuNPs and d-PAV-AuNPs, respectively. They had same chemical composition and surface grafting density but different surface chirality. The isothermal titration calorimetry results showed that adsorption of bovine serum albumin onto the l-PAV-AuNPs and d-PAV-AuNPs was primarily driven by electrostatic interaction. Dynamic light scattering, circular dichroism spectroscopy, fluorescence quenching, and isothermal titration calorimetry characterizations revealed that bovine serum albumin molecules adopted both side-on and end-on configurations on the d-PAV-AuNPs, whereas only end-on configuration on the l-PAV-AuNPs.

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