Visible and Near-Infrared Dual-Emission Carbogenic Small Molecular Complex with High RNA Selectivity and Renal Clearance for Nucleolus and Tumor Imaging

Abstract

Fluorescence imaging requires bioselective, sensitive, nontoxic molecular probes to detect the precise location of lesions for fundamental research and clinical applications. Typical inorganic semiconductor nanomaterials with large sizes (>10 nm) can offer high-quality fluorescence imaging due to their fascinating optical properties but are limited to low selectivity as well as slow clearance pathway. We here report an N- and O-rich carbogenic small molecular complex (SMC, MW < 1000 Da) that exhibits high quantum yield (up to 80%), nucleic acid-binding enhanced excitation-dependent fluorescence (EDF), and a near-infrared (NIR) emission peaked at 850 nm with an ultralarge Stokes shift (∼500 nm). SMCs show strong rRNA affinity, and the resulting EDF enhancement allows multicolor visualization of nucleoli in cells for clear statistics. Furthermore, SMCs can be efficiently accumulated in tumor in vivo after injection into tumor-bearing mice. The NIR emission affords high signal/noise ratio imaging for delineating the true extent of tumor. Importantly, about 80% of injected SMCs can be rapidly excreted from the body in 24 h. No appreciable toxicological responses were observed up to 30 days by hematological, biochemical, and pathological examinations. SMCs have great potential as a promising nucleolus- and tumor-specific agent for medical diagnoses and biomedical research.

Renal Clearable Luminescent WSe2 for Radioprotection of Nontargeted Tissues during Radiotherapy

“…The blood circulation showed a blood half time of 0.5 h for cysteine‐protected WSe 2 dots (Figure c). Renal clearance is crucial for medical applications of any material, and thus ultrasmall systems (<5.5 nm), such as metal clusters, quantum dots, and small molecules have attracted extensive attentions. Therefore, the increasing clinical demand can be potentially filled by ultrasmall radioprotectants.…”

Bioimaging Applications of Carbon Nanodots: A Review

“…This highlights that the CNDs can be used for imaging of nucleolus, even in cases that commercially available dyes are inefficient. In a similar study, He et al took advantage of the selectivity of CNDs of higher molecular weight for RNA over DNA and utilized them to label cell nucleoli, where RNA exists at higher content levels [71]. Fluorescence signals were also recorded in the cytoplasm of cells ascribed to the presence of RNA.…”

Surface charge controlled nucleoli selective staining with nanoscale carbon dots

“…Carbon dots preparation: carbon dots were made according to literature [45] with slight modification. Briefly, 1.6 g of CA (1 mol) was dissolved in 10 mL of water, and mixed with 0.21 (0.5 mol), 0.42 (1 mol), 0.83 (2 mol) or 1.66 mL (3 mol) of EDA, respectively, followed by stirring to form a homogeneous solution.…”

“…Carbon dots made from citric acid (CA) and ethylenediamine (EDA) have also been studied for bioimaging [45,46]. However, the influence of surface charge to nucleoli staining ability has not been reported.…”