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Background: Malignant pleural effusion is mostly a complication of advanced malignant tumors. However, the cancer markers such as carbohydrate antigen 125 (CA 125), carbohydrate antigen 15-3 (CA 15-3), carbohydrate antigen 19-9 (CA 19-9), and cytokeratin fragment 21-1 (CYFRA 21-1) have low sensitivity and organ specificity for detecting malignant pleural effusion. Research question: Is IR808@MnO nano-near infrared fluorescent dye worthy for the diagnosis in differentiating benign and malignant pleural effusions. Study design and methods: This experiment was carried out to design and characterize the materials for in vitro validation of the new dye in malignant tumor cells in the A549 cell line and in patients with adenocarcinoma pleural effusion. The dye was verified to possess tumor- specific targeting capabilities. Subsequently, a prospective hospital-based observational study was conducted, enrolling 106 patients and excluding 28 patients with unknown diagnoses. All patients underwent histopathological analysis of thoracoscopic biopsies, exfoliative cytological analysis of pleural fluid, and analysis involving the new dye. Statistical analyses were performed using Microsoft Excel, GraphPad Prism, and the R language. Results: The size of IR808@MnO was 136.8 ± 2.9 nm, with peak emission at 808 nm, and it has near-infrared fluorescence properties. Notably, there was a significant difference in fluorescence values between benign and malignant cell lines (p < 0.0001). The malignant cell lines tested comprised CL1-5, A549, MDA-MB-468, U-87MG, MKN-7, and Hela, while benign cell lines were BEAS-2B, HUVEC, HSF, and VE. The most effective duration of action was identified as 30 min at a concentration of 5 μl. This optimal duration of action and concentration were consistent in patients with lung adenocarcinoma accompanied by pleural effusion and 5 μl. Of the 106 patients examined, 28 remained undiagnosed, 39 were diagnosed with malignant pleural effusions, and the remaining 39 with benign pleural effusions. Employing the new IR808@MnO staining method, the sensitivity stood at 74.4%, specificity at 79.5%, a positive predictive value of 69.2%, and a negative predictive value of 82.1%. The area under the ROC curve was recorded as 0.762 (95% CI: 0.652–0.872). The confusion matrix revealed a positive predictive value of 75.7%, a negative predictive value of 75.6%, a false positive rate of 22.5%, and a false negative rate of 26.3%. Interpretation: The IR808@MnO fluorescent probe represents an efficient, sensitive, and user-friendly diagnostic tool for detecting malignant pleural fluid, underscoring its significant potential for clinical adoption. [ABSTRACT FROM AUTHOR]

Intracellular pH was tightly regulated in many biological processes in which cells must control pH changes within a precise range. Hence, tracing intracellular pH variation was important for understanding the physiological and pathological processes. Although fluorescent probes can be a necessary tool for detecting changes in pH, there are many limitations to existing probes, such as background interference, large cytotoxicity, and poor permeability, which need to be urgently overcome. In this work, a ratiometric and colorimetric chemosensor based on spiropyran (SP-DCCH) was fabricated for monitoring pH change using fluorescence resonance energy transfer mechanism. SP-DCCH has demonstrated the advantages of high sensitivity and selectivity, outstanding permeability and hypotoxicity. Moreover, SP-DCCH displays a pH-sensitive response from 1.68 to 7.21 (p K a = 4.87) and a linear response from pH 3.81 to 6.01, which was desirable for detecting pH change in living biosystem. As expected, the results confirmed that the response signal was pH-dependent and regulated via switchable forms between spiropyran and merocyanine. Spectacularly, SP-DCCH has successfully realized sensing and mapping pH in living cells, P. aeruginosa and zebrafish. The above results exhibited that SP-DCCH could be a powerful tool for sensing and visualizing pH in living systems. Image 1 • Spiropyran-based sensor SP-DCCH has been employed for visual recognition and quantification of pH change. • SP-DCCH can be switchable sensor of pH with colorimetric/ratiometric responses via spiropyran and merocyanine. • The response mechanism of SP-DCCH was excavated by time-dependent density functional theory. • SP-DCCH has successfully realized pH mapping in living cells, bacteria and zebrafish. [ABSTRACT FROM AUTHOR]

• Novelty sensor has employed to sense ClO− with ratiometric and colorimetric. • The sensing mechanism was explored by theoretical calculation. • The chemosensors for ClO− successful response in cells, bacteria and zebrafish. • Visualized fluorescence recovery of ClO− can be realized on filter paper. Hypochlorous acid (HOCl)/hypochlorite (ClO−) was a biologically important component of reactive oxygen species (ROS) and plays a key role in human immune function systems. HOCl/ClO− can destroy invasive bacteria and pathogens, and mediate the physiological balance of the organism with low concentrations, and cause oxidation of the biomolecules such as proteins, cholesterol and nucleic acid in biological cells, leading to a series of diseases with over capacity. Therefore, quantifying the content of HOCl/ClO− in organisms are extremely urgent. In this work, coumarin-salicylic hydrazide Schiff base (CMSH), a ratiometric and colorimetric fluorescent probe for ClO- detection based on coumarin as the fluorophore unit was rationally designed and synthesized. The results indicated that CMSH exhibits high selectivity and sensitivity for ClO- identification. Additionally, the ratios (I 470 /I 532) displayed brilliant ClO−-dependent quick and sensitive performance within 40 s and limitation of 128 nM, respectively. As well as the color of the solution changes from green to colorless accompanied by the fluorescence form green turns into blue with addition of ClO−. Totally, CMSH has been successfully employed as ratiometric sensor to image in living cells, bacteria and zebrafish with low cytotoxicity and good permeability. [ABSTRACT FROM AUTHOR]

Acid-alkaline balance plays a crucial role in all biological processes. Accordingly, monitoring pH changes will help us to understand the functional status of these physiological and pathological processes. Though fluorescent probes may be a useful tool for detecting pH changes, and there are many limitations to currently available probes, such as background interference, potential cytotoxicity, and poor cell permeability, which call for a solution urgently. In this work, a rhodamine-derived colorimetric and ratiometric sensor (Rh–HN) was fabricated for monitoring pH change via the mechanism of fluorescence resonance energy transfer (FRET). Rh–HN has been shown to possess several advantages over other probes, such as high sensitivity, outstanding permeability, and low toxicity. Besides, the fluorescence intensity ratio (F 526 /F 592) of Rh–HN displays a pH-sensitive response from 2.0 to 7.5 (p K a = 5.05) and linear response from pH 3.8 to 6.4, which was desirable for mapping pH change in the biological systems. Besides, the results indicated that Rh–HN generated a pH-dependent response regulated by switchable forms between closed and opened spirolactam ring. Overall, Rh–HN has accomplished sensing and mapping of pH in living cells, bacteria, and zebrafish. Those results demonstrated that the great potential of Rh–HN in sensing and visualizing pH in the living biosystem. Image 1 • A Rhodamine-derived sensor Rh–HN was developed to visualize and monitor pH variation with p K a = 5.05. • Rh–HN exhibited reversible colorimetric/ratiometric responses to pH by switching of closed and opened spirolactam. • Response mechanism of Rh–HN was revealed by density functional theory calculation. • Rh–HN has successfully accomplished pH mapping in living cells, bacteria and zebrafish. [ABSTRACT FROM AUTHOR]

Gallium, aluminum, and indium belong to Group IIIA of the periodic table with similar chemical properties, which were a double-edged sword for living organisms. Therefore, it's particularly important to detect the content of Group IIIA in organisms. Obviously, the fluorescent probe method has become a mainstream method for detecting metal ions with advantages of convenience and high efficiency. Unfortunately, fluorescent probes that can simultaneously detect these three metal ions are rarely reported. 3-hydroxyflavone (3-HF) is a highly focused molecule with chemical and photochemical properties and have great potential for bioimaging applications as sensors with excited-state intramolecular proton transfer (ESIPT). Here, 3-HF as ratiometric fluorescence probes have been developed for responding to Group IIIA ions including Ga(III), Al(III) and In(III) ions with ESIPT-based mechanism. 3-HF displayed highly specific sensing for Group IIIA ions over other cations with a green fluorescence transformation into blue fluorescence by the formation of 2:1 complexes. However, rapid response toward Group IIIA ions was developed using ratiometric fluorescence with wide pH range and good reversibility, and the response mechanism of 3-HF toward Group IIIA ions was annotated by density functional theory (DFT). Furthermore, the biological applicability of 3-HF has shown that 3-HF were able to detect and image Group IIIA ions in cells. Additionally, using a zebrafish model, we exhibited the capability of this 3-HF probe for detecting and imaging Group IIIA ions in zebrafish. This work achieves the detection and imaging of Group IIIA simultaneously by 3-HF probe in living cells and zebrafish and provides another example for "ESIPT OFF". Image 1 • Flavone-based probe detected Group IIIA with high selectivity and sensibility. • Responding mechanism of probe towards Group IIIA was exhibited by DFT. • 3-HF as ratiometric probe sensing Group IIIA with bioimaging in cells and zebrafish. [ABSTRACT FROM AUTHOR]