Synthesis of g-C3N4 nanosheet/Au@Ag nanoparticle hybrids as SERS probes for cancer cell diagnostics

Abstract

Chemical sensing for the convenient detection of cancer cells has been widely explored with the use of various sensing materials and techniques, but it is still a challenge to achieve ultrasensitive, simple, rapid and inexpensive detection of cancer cells. Herein, we report a surface-enhanced Raman scattering (SERS) method for the detection of cancer cells in situ. In our work, ultrathin g-C₃N₄ nanosheet/Au@AgNP hybrids (g-C₃N₄/Au@AgNPs) were fabricated using a self-assembly strategy, in which poly(ethyleneimine) (PEI) was used to obtain cationic polyelectrolyte-modified ultrathin nanosheets and anchor the Au@AgNPs. The g-C₃N₄ nanosheets exhibited a strong enrichment ability and the self-assembled Au@AgNPs showed an excellent SERS activity, both of which led to an ultrahigh sensitivity. The hybrids were applied to detect folic acid (FA) with the sensitive detection limit of 2.41 nM. Importantly, after being modified with FA, which targeted cancer cells with folate receptors (FRs), the formed g-C₃N₄/Au@AgNPs–FA was used as a SERS probe for the on-site monitoring of cancer cells with FA as the Raman reporter molecule.