Strong blue fluorescent polyethylene glycol (PEG) anchored carbon nitride dots (CDs@PEG) with a high quantum yield (QY) of 75.8% have been synthesized by a one step hydrothermal treatment. CDs with a diameter of ca. 6 nm are well dispersed in water and present a graphite-like structure. Photoluminescence (PL) studies reveal that CDs display excitation-dependent behavior and are stable under various test conditions. Based on the as-prepared CDs, we designed novel cell nucleus targeting imaging carbon dots functionalized with a nuclear localization signal (NLS) peptide. The favourable biocompatibilities of CDs and NLS modified CDs (NLS-CDs) are confirmed by in vitro cytotoxicity assays. Importantly, intracellular localization experiments in MCF7 and A549 cells demonstrate that NLS-CDs could be internalized in the nucleus and show blue light, which indicates that CDs may serve as cell nucleus imaging probes.

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Carbon dots (CDs) have shown great potential in imaging and drug/gene delivery applications. In this work, CDs functionalized with a nuclear localization signal peptide (NLS-CDs) were employed to transport doxorubicin (DOX) into cancer cells for enhanced antitumor activity. DOX was coupled to NLS-CDs (DOX-CDs) through an acid-labile hydrazone bond, which was cleavable in the weakly acidic intracellular compartments. The cytotoxicity of DOX-CD complexes was evaluated by the MTT assay and the cellular uptake was monitored using flow cytometry and confocal laser scanning microscopy. Cell imaging confirmed that DOX-CDs were mainly located in the nucleus. Furthermore, the complexes could efficiently induce apoptosis in human lung adenocarcinoma A549 cells. The in vivo therapeutic efficacy of DOX-CDs was investigated in an A549 xenograft nude mice model and the complexes exhibited an enhanced ability to inhibit tumor growth compared with free DOX. Thus, the DOX-CD conjugates may be exploited as promising drug delivery vehicles in cancer therapy.

A novel lysosome-targeting ratiometric fluorescent probe (CQ-Lyso) based on the chromenoquinoline chromorphore has been developed for the selective and sensitive detection of intracellular pH in living cells. In acidic media, the protonation of the quinoline ring of CQ-Lyso induces an enhanced intramolecular charge transfer (ICT) process, which results in large red-shifts in both the absorption (104 nm) and emission (53 nm) spectra which forms the basis of a new ratiometric fluorescence pH sensor. This probe efficiently stains lysosomes with high Pearson's colocalization coefficients using LysoTrackerDeep Red (0.97) and LysoTrackerBlue DND-22 (0.95) as references. Importantly, we show that CQ-Lyso quantitatively measures and images lysosomal pH values in a ratiometric manner using single-wavelength excitation.

The novel GCKT-liposomes significantly improved the antitumour efficacy of GCK.

Thiols, such as cysteine (Cys), homocysteine (Hcy), glutathione (GSH), hydrogen sulfide (HS), and thiophenol are metabolically correlated with each other via redox reactions. As a result of the similarity of chemical properties between Cys, Hcy, GSH, HS, and thiophenol, it is very challenging to develop an effective methodology to differentiate them. In this work, a triple-emission fluorescent probe, NCQ, was reported for the simultaneous detection of Cys/Hcy, GSH/HS, and thiophenol with high sensitivity and selectivity. The solution of NCQ displayed distinct fluorescent signals toward Cys/Hcy, GSH/HS, and thiophenol: blue and green for Cys/Hcy, blue for GSH/HS, blue and red for thiophenol. Through the blue-green-red emission color combination, Cys/Hcy, GSH/HS, and thiophenol could be discriminatively detected in solution and in living cells.

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Ginsenoside compound K (CK) is one of the effective ingredients in antitumor composition of ginsenoside. However, the poor water solubility and significant efflux have limited the widespread clinical use of CK. In this study, preparation of novel CK-loaded d -alpha-tocopheryl polyethylene glycol 1,000 succinate/poly(ethylene glycol)-poly(ε-caprolactone) mixed micelles (CK-M) is discussed to solve the above problems. Particle size, zeta potential, and morphology were characterized using dynamic light scattering and transmission electron microscopy. CK-M are spherical shaped with an average particle size of 53.07±1.31 nm with high drug loading of 11.19%±0.87% and entrapment efficiency of 94.60%±1.45%. Water solubility of CK was improved to 3.78±0.09 mg/mL, which was ~107.35 times higher than free CK. A549 and PC-9 cells were used to evaluate in vitro cytotoxicity and cellular uptake. IC 50 values of CK-M in A549 and PC-9 cells (24 h) were 25.43±2.18 and 18.35±1.90 μg/mL, respectively. Enhanced cellular uptake of CK-M was observed in both cells. Moreover, CK-M promoted tumor cell apoptosis, inhibited tumor cell invasion, metastasis, and efflux through regulation of Bax, Bcl-2, matrix metalloproteinase-2, Caspase-3, and P-glycoprotein. In vivo imaging indicated that CK-M has excellent tumor targeting effect within 24 h, and the relative tumor inhibition rate of CK-M was 52.04%±4.62% compared with control group ( P <0.01). Thus, CK-M could be an appropriate delivery agent for enhanced solubility and antitumor effect of CK.