Multiple organelle-targeted 1,8-naphthyridine derivatives for detecting the polarity of organelles

Four 1,8-naphthyridine derivatives (1a-1d) with different organelle targeting abilities were obtained using the Knoevenagel condensation reaction of 1,8-naphthyridine with 4-(N,N-diethylamino)benzaldehyde (2a), 4-(N,N-diphenylamino)benzaldehyde (2b), 4-(piperazin-1-yl)benzaldehyde (2c) and 4-(ethyl(4-formylphenyl)amino)-N-(2-((4-methylphenyl)sulfonamido)ethyl)butanamide (2d), respectively. The maximal absorption bands of dyes 1a-1d were observed at 375-447 nm, while their maximum emission peaks were situated at 495-605 nm. The optical properties showed that the fluorescence emission of dyes 1a-1d is shifted toward greater wavelengths as the system polarity (Δf) increased. Meanwhile, with increasing polarity of the mixed 1,4-dioxane/H₂O system, the fluorescence intensity of dyes 1a-1d gradually decreased. Furthermore, the fluorescence intensity of 1a-1d enhanced by 12-239 fold as the polarity of 1,4-dioxane/H₂O mixtures declined. 1a-1d had a large Stokes shift (up to 229 nm) in polar solvents in comparison to nonpolar solvents. The colocalization imaging experiments demonstrated that dyes 1a-1d (3-10 μM) were located in mitochondria, lipid droplets, lysosomes and the endoplasmic reticulum in living HeLa cells, respectively; and they could monitor the polarity fluctuation of the corresponding organelles. Consequently, this work proposes a molecular design idea with different organelle targeting capabilities based on the same new fluorophore, and this molecular design idea may provide more alternatives for polarity-sensitive fluorescent probes with organelle targeting.

Distinguishing cancer cells from normal cells with an organelle-targeted fluorescent marker

In this paper we report a hemicyanine dye that is used to distinguish cancer cells from normal cells with its ability to target different organelles. Probe 1, a red emission hemicyanine functional dye, was connected to oxazolo[4,5-b]pyridine and diethylaminobenzene with a double bond. The maximum absorption peaks of probe 1 were located in the 509-552 nm range in organic solvents. Meanwhile, the probe possessed a high molar extinction coefficient (5.50 × 10⁴ M^-1 cm^-1 in DMSO) with high photostability. The maximum emission wavelength of the probe ranged from 572 nm to 644 nm, and it also had a large Stokes shift (126 nm in DMSO). In particular, the probe showed weak fluorescence in water (Φ = 0.016), whereas it displayed strong fluorescence at 595 nm in β-cyclodextrin (β-CD) solution (Φ = 0.13). In addition, cell colocalization experiments showed that probe 1 (3 μM) was located in the endoplasmic reticulum in cancer cells, while it could target lysosomes in normal cells. What's more, further cell imaging experiments demonstrated that the average fluorescence intensity of probe 1 (0.3 μM) in cancer cells increased with the addition of β-CD, but it did not occur in normal cells. The study provides a convenient way to distinguish cancer cells from normal ones, which has potential for application in the early detection of cancer.

[Application of nuclear magnetic dispersion weighted imaging and apparent diffusion coefficient in the identification of benign]

Objective:To determine the diagnostic role of diffusionweighted imaging(DWI) and apparent diffusion coefficient（ADC） under different b values in differentiating benign and malignant thyroid nodules by using postoperative histopathological results were taken as the reference standard. Method: From January 2017 to June 2018, 64 patients with thyroid nodules diagnosed by ultrasound in the head and neck surgery of Shanxi Cancer Hospital were collected, and a total of 80 nodules were collected. The Philips 3.0T superconducting magnetic resonance imaging system was used for T1 weighting, T2 weighting, and DWI horizontal axis scanning imaging. The b values were 300, 500, 800 and 1 000 s/mm², respectively. Taking postoperative histopathological results as the reference standard, the ADC values of thyroid nodules of all subjects were calculated and compared, and the working characteristics(ROC) curves of all subjects with b values were drawn, the area under the curve was calculated, and the threshold value of differentiating benign and malignant thyroid nodules was obtained. Result:A total of 80 nodules, 33 malignant and 43 benign were excluded, including 1 diffuse b-cell non-hodgkin's lymphoma, 2 parathyroid cysts, and 1 pure cystic patient. A total of 76 nodules were included. When b values were 300, 500, 800 and 1 000 s/mm², the average ADC values of malignant nodules were(1.498±0.210) ×10⁻³mm²/s, (1.311±0.190) ×10⁻³mm²/s, (1.134±0.170) ×10⁻³mm²/s, (0.972±0150) ×10⁻³mm²/s. The mean ADC values of benign nodules were(2.207±0.390) ×10⁻³mm²/s, (1.928±0.430) ×10⁻³mm²/s, (1.702±0.410) ×10⁻³mm²/s,(1.557±0.420) ×10⁻³mm²/s. At the same b value, the average ADC value of malignant nodules was lower than that of benign nodules, and the difference was statistically significant(t values were 9.279,7.641,7.301,7.569, P values were 0.000,0.000,0.000,0.000,0.000). The average ADC values of the benign and malignant nodules decreased with the increase of b value, and the difference was statistically significant(the F values of the benign and malignant groups were 210.091 and 353.822, respectively，P values are 0.000, 0.000). Under different b values, the area(AUC) of ROC curve is 0.927,0.884,0.878,0.901,and 95%CI are 0.862-0.993,0.804-0.956,0.794-0.962 and 0.829-0.972, respectively. When b value is 300 s/mm², AUC is the largest, indicating that it is the best indicator to distinguish benign and malignant thyroid nodules. The diagnostic threshold of benign and malignant nodules is 1.802×10⁻³mm²/s. Specificity, sensitivity, accuracy, positive predictive value, and negative predictive value were 95.00%,86.11%,90.79%,93.94% and 88.37%, respectively. Conclusion: DWI is a noninvasive diagnostic tool used to identify benign and malignant thyroid nodules. It can help to make a definite diagnosis before surgery and reduce the unnecessary burden of surgery.