Xiaoqian Ge

Nile Red Derivative-Modified Nanostructure for Upconversion Luminescence Sensing and Intracellular Detection of Fe3+ and MR Imaging

Iron ion (Fe(3+)) which is the physiologically most abundant and versatile transition metal in biological systems, has been closely related to many certain cancers, metabolism, and dysfunction of organs, such as the liver, heart, and pancreas. In this Research Article, a novel Nile red derivative (NRD) fluorescent probe was synthesized and, in conjunction with polymer-modified core-shell upconversion nanoparticles (UCNPs), demonstrated in the detection of Fe(3+) ion with high sensitivity and selectivity. The core-shell UCNPs were surface modified using a synthesized PEGylated amphiphilic polymer (C18PMH-mPEG), and the resulting mPEG modified core-shell UCNPs (mPEG-UCNPs) show good water solubility. The overall Fe(3+)-responsive upconversion luminescence nanostructure was fabricated by linking the NRD to the mPEG-UCNPs, denoted as mPEG-UCNPs-NRD. In the nanostructure, the core-shell UCNPs, NaYF4:Yb,Er,Tm@NaGdF4, serve as the energy donor while the Fe(3+)-responsive NRD as the energy acceptor, which leads to efficient luminescence resonance energy transfer (LRET). The mPEG-UCNPs-NRD nanostructure shows high selectivity and sensitivity for detecting Fe(3+) in water. In addition, benefited from the good biocompatibility, the nanostructure was successfully applied for detecting Fe(3+) in living cells based on upconversion luminescence (UCL) from the UCNPs. Furthermore, the doped Gd(3+) ion in the UCNPs endows the mPEG-UCNPs-NRD nanostructure with effective T1 signal enhancement, making it a potential magnetic resonance imaging (MRI) contrast agent. This work demonstrates a simple yet powerful strategy to combine metal ion sensing with multimodal bioimaging based on upconversion luminescence for biomedical applications.

Fast fabrication of transparent and multi-luminescent TEMPO-oxidized nanofibrillated cellulose nanopaper functionalized with lanthanide complexes

We designed an easy-to-fabricate multi-luminescent nanopaper with high transparency, for the first time, by grafting lanthanide complexes [Eu(dbm)3(H2O)2, Sm(dbm)3(H2O)2, Tb(tfacac)3(H2O)2] on TEMPO mediated oxidized nanofibrillated cellulose (ONFC). The lanthanide complex functionalized ONFC nanopaper (Ln–ONFC nanopaper, Ln = Eu, Sm, Tb) with uniform luminescence was rapidly fabricated after solvent exchange using a press-controlled extrusion papermaking method. The new TEMPO-induced carboxyl groups on the surface of ONFC provided the possibility to participate in the coordination with lanthanide ions and then to construct heterogeneous network architectures. The fluorescent properties of the Ln–ONFC hybrid nanopaper were significantly influenced by the amount of lanthanide complexes and the solvent medium during the extrusion. Based on simple manipulation and mild conditions, a highly transparent NFC template provided a soft matrix and afforded the high thermal stability and excellent luminescent properties of the Ln–ONFC nanopaper, which yields ever increasing potential to supersede petroleum-based materials for diverse applications.

Light modulation (vis-NIR region) based on lanthanide complex-functionalized carbon dots

A new kind of carbon dots with an average diameter of approximately 3–5 nm were synthesized using L-lysine. Subsequently, a series of lanthanide complex-functionalized carbon dots were designed and synthesized, denoted as Ln-CDs (Ln = Eu, Sm, Er, Yb, Nd). In addition, by changing the ratio of Eu complexes and carbon dots, four kinds of Eu complex-functionalized carbon dots were also obtained (Eu-CDs-1, Eu-CDs-2, Eu-CDs-3, Eu-CDs-4). The derived nanomaterials were characterized by Fourier-transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and fluorescence spectroscopy. Upon visible-light excitation, these lanthanide complex-functionalized carbon dots show multicolor visible (Eu; with red, orange, grey and blue colors, respectively) and near-infrared (Sm, Er, Nd, Yb) luminescence (emission covered from 400 nm to 1700 nm spectral region).