In situ synthesis of gold nanoparticles on layered double hydroxide nanoparticles for multiplexing molecular imaging of single cells

Abstract

Quasi-spherical gold nanoparticles (AuNPs) are the most widely used surface-enhanced Raman scattering (SERS) nanotags. However, their surface plasmon resonance properties are significantly restricted by their poor colloidal stability in biological media. Herein, we developed a new strategy for in situ synthesis of AuNPs on layered double hydroxide (LDH) nanoparticles to improve the colloidal stability of AuNPs for SERS imaging with multiplexing capability using single laser excitation. The hybridized LDH-AuNPs were constructed via in situ growth of AuNPs on lactic acid-LDH nanoparticles. The size of AuNPs was tuned by changing the concentration of LDH. The LDH-AuNPs were further functionalized with Raman reporter molecules (Ra) to obtain LDH-AuNPs-Ra as SERS nanotags, which were examined in terms of the colloidal stability and photostability in biological media as well as cellular uptake in J774A.1 macrophage cell culture by single cell mapping via confocal Raman microscopy. The cellular uptake of multiple LDH-AuNPs-Ra functionalized with different Raman reporter molecules were further investigated, where the multiplexing capability of SERS assay endows simultaneous detection of multiple LDH-AuNPs-Ra distribution after cellular uptake for cell imaging. In summary, the LDH-supported in situ synthesis of AuNPs have shown the merits of stabilizing AuNPs by using LDH for SERS imaging, as well as demonstrating the multiplexing molecular imaging of single cells. This work thus provides a promising strategy and a new bioimaging nanoplatform for various biomedical studies in the near future.