Tumorigenesis is closely related to the loss of control of many genes. Urokinase-type plasminogen activator receptor (uPAR), a glycolipid-anchored protein on the cell surface, is controlled by many factors in tumorigenesis and is expressed in many tumor tissues. In this review, we summarize the regulatory effects of the uPAR signaling pathway on processes and factors related to tumor progression, such as tumor cell proliferation, adhesion, metastasis, glycolysis, tumor microenvironment and angiogenesis. Overall, the evidence accumulated to date suggests that uPAR induction by tumor progression may be one of the most important factors affecting therapeutic efficacy. An improved understanding of the interactions between uPAR and its coreceptors in cancer will provide critical biomolecular information that may help to better predict the disease course and response to therapy.

A dual colorimetric and ratiometric fluorescent assay is constructed for the detection of glutathione (GSH) based on MnO 2 nanosheets (MnO 2 NS). Amplex Red (AR) and curcumin (CUR) fluorescence-pairing probes have opposite responses to MnO 2 NS with fluorescence quenching and oxidaselike property. MnO 2 nanosheets can largely quench the fluorescence of curcumin. However, the fluorescence of oxidized AR (oxAR) was obviously raised via the catalytic oxidation reaction of no fluorescent AR. The color of the solution gradually changes from yellow to orange. However, MnO 2 nanosheets lose the fluorescence quenching capacity and oxidase-like property after the addition of GSH. Therefore, the fluorescence intensity of curcumin shows an obvious increase and the intensity of oxAR a decrease, accompanied by the restoration of the solution color from orange to yellow. For MnO 2 nanosheets, the linear relationship between the absorbance ratio of the two substrates and the GSH concentration (50−15 000 nM) is obtained with the detection limit of 16 nM. Besides, the ratiometric fluorescent method has a good linear range from 10 to 5000 nM for GSH. The detection limit is as low as 4.2 nM. Further, this method can not only be used for the determination of GSH in an aqueous solution but also shows a high responsive ability to GSH in human serum. This result indicates its potential in bioanalysis and disease diagnosis.

In this work, bare gold nanoparticle−metal ion ensembles were screened to build a colorimetric sensor array for the ultrasensitive detection of various phosphates such as adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), pyrophosphate (PPi), and phosphate (Pi). First, we found that the bare gold nanoparticle (BGNP) surface with no functional groups exhibited the highest peroxidase-like activity among hexadecyl trimethylammonium bromide-coated gold nanoparticles (CTAB-GNPs), citric acid-functionalized gold nanoparticles (Cit-GNPs), and BGNPs. Afterward, three metal ions (Ce 3+ , Fe 2+ , and Cr 3+ ) were screened to enhance the enzymatic catalytic activity of BGNPs further, greatly through the electrostatic interaction between AuCl 4 − /AuCl 2 − ions on the surface of BGNPs and metal ions, because the metal ions could activate the redox cycle reaction of the BGNP−metal ions. However, the catalytic activity of BGNP−metal ion ensembles was inhibited after the addition of phosphates because of the high affinities between phosphates and metal ions. Inspired by the above phenomena, a colorimetric sensor array was constructed for ultrasensitive determination and identification of phosphates based on the tunable peroxidase-like activity of BGNP−metal ion ensembles. The colorless substrates 3,3′,5,5′tetramethylbenzidine (TMB) were catalytically oxidized by BGNP−metal ion ensembles to form a blue oxidation product (ox-TMB) as the color signal. This sensor array consisted of three sensing elements (BGNPs-Ce 3+ , BGNPs-Fe 2+ , and BGNPs-Cr 3+ ) and generated cross-reactive signals with each phosphate because of the high difference in the number of phosphate groups, geometry, steric effect, and binding sites. The colorimetric sensor array was successfully applied to differentiate five phosphates at 0.25 μM in aqueous solutions. More importantly, the as-designed sensor array was successfully explored to monitor nucleotide phosphateinvolved enzymatic hydrolysis processes and their metabolites as well as to analyze phosphates in biological samples.

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