Recent progress in the development of near-infrared fluorescent probes for bioimaging applications

Abstract

Near-infrared (NIR) fluorescent dyes have emerged as promising modalities for monitoring the levels of various biologically relevant species in cells and organisms. The use of NIR probes enables deep photon penetration in tissue, minimizes photo-damage to biological samples, and produces low background auto-fluorescence from biomolecules present in living systems. The number of new analyte-responsive NIR fluorescent probes has increased substantially in recent years as a consequence of intense research efforts. In this tutorial review, we highlight recent advances (2010-2013) made in the development and applications of NIR fluorescent probes. The review focuses on NIR fluorescent probes that have been devised to sense various biologically important species, including ROS/RNS, metal ions, anions, enzymes and other related species, as well as intracellular pH changes. The basic principles involved in the design of functional NIR fluorescent probes and suggestions about how to expand applications of NIR imaging agents are also described.

Neutral N^C^N terdentate luminescent Pt(ii) complexes: their synthesis, photophysical properties, and bio-imaging applications

“…[15][16][17][18] Another fast emerging field regarding luminescent Pt(II) complexes is their application as luminescent labels for bioimaging. [19][20][21][22][23] Although fluorescent organic labels are still the leading choice for such applications, [24][25][26] phosphorescent Pt(II) complexes are slowly gaining attention and could outclass organic molecules. In fact, Pt complexes display many advantages such as: (i) a wide emission colour tunability by an adequate choice of the ligands; (ii) a better stability towards photo-and chemical degradation; (iii) a very large Stokes shift that allows the detection of their emission at a much lower energy than the excitation energy; (iv) long-lived luminescent excited states owing to their triplet-manifold nature; (v) emission lifetimes typically two to three orders of magnitude longer than those of classic organic fluorophores.…”

Advances in In Vivo Imaging Techniques for the Visualization and Quantification of DC-T Cell Interactions

“…However, a new generation of NIR dyes, which allow for deep tissue penetration, minimal photo damage and low background auto fluorescence are currently being developed, including squaraine and squaraine-rotaxanes derivatives, with cross sections of 33,000 GM and molecular weights much smaller than current quantum dots, the results of early studies are proving promising for the development of novel tools for subcellular imaging [17][18][19]. Additionally, fluorescent proteins [20] and nanotube-based optical sensors [21] that are excitable in the 1000-1300 nm range are being designed to allow for imaging at greater depths than what is achievable with conventional fluorophores.…”

Organic Nanoprobes for Fluorescence and 19F Magnetic Resonance Dual‐Modality Imaging

“…[12,13] Compared with other bioimaging techniques, FI displays more advantages of high sensitivity, easy operation, and cost-effectiveness, [14][15][16][17][18][19] which can also trace real-time cellular processes over a long period of time but lacks penetration depth for the internal organs, especially in view of in vivo applications. [20][21][22] With respect to MRI technique, [23][24][25] it is noninvasive and nondestructive, and can offer high spatial resolution, whereas it shows low sensitivity. Thus, integration of these two complementary imaging modalities into one single imaging agent is highly desirable for biomedical applications.…”