In vitro Derby Imaging of Cancer Biomarkers Using Quantum Dots

Semiconductor quantum dots (QDs), which have broad absorption with narrow emission spectra, are useful for multiplex imaging. Here, fluorescence derby imaging using dual color QDs conjugated by the AS1411 aptamer (targeting nucleolin) and the arginine–glycine–aspartic acid (targeting the integrin α_vβ₃) in cancer cells is reported. Simultaneous fluorescence imaging of cellular distribution of nucleolin and integrin α_vβ₃ using QDs enables easy monitoring of separate targets in the cancer cells and the normal healthy cells. These results suggest the feasibility of a concurrent visualization of QD‐based multiple cancer biomarkers using small molecules such as aptamer or peptide ligands.     

Nanofiber‐Directed Anisotropic Self‐Assembly of CdSe–CdS Quantum Rods for Linearly Polarized Light Emission Evidenced by Quantum Rod Orientation Microscopy

Hybrid soft materials composed of CdSe–CdS nanorods or “quantum rods” (QRs) and the fluorescent 2,3‐didecyloxyanthracene (DDOA) low molecular weight organogelator are obtained through self‐assembly. Spectroscopy, microscopy, and rheology studies show that the QRs and DDOA coassemble, thereby stabilizing the organogels. Depending on the QR load and excitation wavelength, single nanofibers (NFs) of the hybrid gel display either sharp polarized red luminescence (under green excitation), or dual perpendicularly polarized blue and red emissions (under UV excitation). Transmission electron microscopy, microspectroscopy, and quantum rod orientation microscopy (QROM) reveal that QRs align along the organogel NFs with order parameters reaching 76% and 87%. This paves the way for obtaining surfaces of QR/NF assemblies yielding sharp red linearly polarized emission. In addition, this work demonstrates that QRs can be used more generally to probe nanostructured soft materials, even nonemissive ones. QROM allows to establish maps of the orientation of single QRs dispersed onto or within a gel network by measuring the polarization of the emission of the individual QRs. As occurs within this work in which QRs and NFs interact, the orientation of each QR reveals information on the underlying nanostructure (such as surface striation, bundle formation, and helicity).     

Highly Luminescent–Paramagnetic Nanophosphor Probes for In Vitro High‐Contrast Imaging of Human Breast Cancer Cells

Highly luminescent–paramagnetic nanophosphors have a seminal role in biotechnology and biomedical research due to their potential applications in biolabeling, bioimaging, and drug delivery. Herein, the synthesis of high‐quality, ultrafine, europium‐doped yttrium oxide nanophosphors (Y_1.9O₃:Eu_0.1³⁺) using a modified sol–gel technique is reported and in vitro fluorescence imaging studies are demonstrated in human breast cancer cells. These highly luminescent nanophosphors with an average particle size of ≈6 nm provide high‐contrast optical imaging and decreased light scattering. In vitro cellular uptake is shown by fluorescence microscopy, which visualizes the characteristic intense hypersensitive red emission of Eu³⁺ peaking at 610 nm (⁵D₀–⁷F₂) upon 246 nm UV light excitation. No apparent cytotoxicity is observed. Subsequently, time‐resolved emission spectroscopy and SQUID magnetometry measurements demonstrate a photoluminescence decay time in milliseconds and paramagnetic behavior, which assure applications of the nanophosphors in biomedical studies.