Rapid Intracellular Growth of Gold Nanostructures Assisted by Functionalized Graphene Oxide and Its Application for Surface-Enhanced Raman Spectroscopy

Hybridization of metal nanoparticles with graphene oxide for high performance surface-enhanced Raman scattering (SERS) has attracted overwhelming attention in recent years. Herein, a one-pot green route for intracellular synthesis of gold nanostructures assisted by poly­(vinylpyrrolidone) (PVP)-functionalized graphene oxide (GO) was proposed. The hybrids obtained [GO/PVP/intracellularly grown gold nanoparticles (IGAuNs)] randomly scattered throughout the cell. Compared with the IGAuNs, the growth of GO/PVP/IGAuNs was remarkably accelerated, which could be attributed to the coordination of PVP enriched on GO. GO/PVP/IGAuNs could serve as excellent SERS probes for ultrasensitive detection of cellular components of cancer cells located in the cytoplasm, nucleoplasm, and nucleolus. The random intracellular distribution of GO/PVP/IGAuNs facilitated the effective Raman characterization of cellular components, which was confirmed by the uniform distribution of SERS signals in the Raman image. The SERS signals induced by GO/PVP/IGAuNs could be collected as early as 15 h, which allowed rapid detection of tumor cells. In conclusion, this facile and green strategy for fast intracellular growth of GO/PVP/IGAuNs offered great potential for biomedical applications

Fabrication of Reduced Graphene Oxide and Sliver Nanoparticle Hybrids for Raman Detection of Absorbed Folic Acid: A Potential Cancer Diagnostic Probe

Reduced graphene oxide (RGO) and silver nanoparticle (AgNP) hybrids (RGO-AgNP) were prepared by a facile one-pot method using Poly (N-vinyl-2-pyrrolidone) as reductant and stabilizer. Folic acid (FA) molecules were attached to the RGO-AgNP by physisorption for targeting specific cancer cells with folate receptors (FRs) and using as Raman reporter molecules. The internalization of the FA loaded RGO-AgNP (RGO-AgNP-FA) inside the FRs-positive cancer cell was confirmed by confocal laser scanning and transmission electron microscopy. The Raman signals of the FA in live cancer cells were detected by confocal Raman spectroscope at 514 nm excitation, indicating that the RGO-AgNP-FA material has great potential as a Raman probe for cancer diagnosis in vitro

Near-Ultraviolet to Near-Infrared Fluorescent Nitrogen-Doped Carbon Dots with Two-Photon and Piezochromic Luminescence

Carbon dots (CDs) have gained intensive interests owing to their unique structure and excellent optoelectronic performances. However, to acquire CDs with a broadband emission spectrum still remains an issue. In this work, nitrogen-doped CDs (N-CDs) with near-ultraviolet (NUV), visible, and near-infrared (NIR) emission were synthesized via one-pot solvothermal strategy, and the excitation-independent NUV and NIR emission and excitation-dependent visible emission were observed in the photoluminescence (PL) spectra of N-CDs. Moreover, the as-synthesized N-CDs displayed two-photon fluorescence emission. It is important to note that N-CDs also exhibited piezochromic luminescence with reversibility, in which the red- and blue-shifted PL with increasing applied pressure (0.07–5.18 GPa) and the red- and blue-shifted PL with releasing applied pressure (5.18 GPa to 1 atm) were developed for the first time. Combined with good hydrophilicity, high photobleaching resistance, and low toxicity, the piezochromic luminescence would greatly boost the valuable applications of N-CDs