Dual-mode detection of 2,6-pyridinedicarboxylic acid based on the enhanced peroxidase-like activity and fluorescence property of novel Eu-MOFs.

2,6-Pyridinedicarboxylic acid (DPA) is a significant biomarker of anthrax, which is a deadly infectious disease for human beings. However, the development of a convenient anthrax detection method is still a challenge. Herein, we report a novel europium metal-organic framework (Eu-MOF) with an enhanced peroxidase-like activity and fluorescence property for DPA detection. The Eu-MOF was one-step synthesized using Eu3+ ions and 2-methylimidazole. In the presence of DPA, the intrinsic fluorescence of Eu3+ ions is sensitized, the fluorescence intensity linearly increases with an increase in DPA concentration, and the fluorescence color changes from blue to purple. Simultaneously, the peroxide-like activity of the Eu-MOF is enhanced by DPA, which can promote the oxidation of TMB to oxTMB. The absorbance values increase linearly with DPA concentrations, and the colorimetric images change from colorless to blue. The dual-mode detection of DPA has good sensitivity with a colorimetric detection limit of 0.67 µM and a fluorescent detection limit of 16.67 nM. Moreover, a simple detection method for DPA was developed using a smartphone with the RGB analysis system. A portable kit with standard color cards was developed using paper test strips. The proposed methods have good practicability for DPA detection in real samples. In conclusion, the developed Eu-MOF biosensor offers a valuable and general platform for anthrax diagnosis.

Increased Apolipoprotein A1 Expression Correlates with Tumor-Associated Neutrophils and T Lymphocytes in Upper Tract Urothelial Carcinoma.

An increased neutrophil-to-lymphocyte ratio (NLR) is a poor prognostic biomarker in various types of cancer, because it reflects the inhibition of lymphocytes in the circulation and tumors. In urologic cancers, upper tract urothelial carcinoma (UTUC) is known for its aggressive features and lack of T cell infiltration; however, the association between neutrophils and suppressed T lymphocytes in UTUC is largely unknown. In this study, we examined the relationship between UTUC-derived factors and tumor-associated neutrophils or T lymphocytes. The culture supernatant from UTUC tumor tissue modulated neutrophils to inhibit T cell proliferation. Among the dominant factors secreted by UTUC tumor tissue, apolipoprotein A1 (Apo-A1) exhibited a positive correlation with NLR. Moreover, tumor-infiltrating neutrophils were inversely correlated with tumor-infiltrating T cells. Elevated Apo-A1 levels in UTUC were also inversely associated with the population of tumor-infiltrating T cells. Our findings indicate that elevated Apo-A1 expression in UTUC correlates with tumor-associated neutrophils and T cells. This suggests a potential immunomodulatory effect on neutrophils and T cells within the tumor microenvironment, which may represent therapeutic targets for UTUC treatment.