Ultrasensitive Tyrosinase-Activated Turn-On Near-Infrared Fluorescent Probe with a Rationally Designed Urea Bond for Selective Imaging and Photodamage to Melanoma Cells

Melanoma is a highly aggressive malignancy and early monitoring and diagnosis are challenging at present. Tyrosinase is overexpressed in melanoma and regarded as an important biological marker for diagnosis and treatment. Thus, the selective and sensitive detection of tyrosinase is of great significance. To date, a few fluorescent probes have been reported for the detection of tyrosinase <i>in vitro</i> or <i>in vivo</i>. However, a highly sensitive near-infrared probe for tyrosinase monitoring is still missing. In this study, the Gibbs free energy change of different urea bonds during spontaneous hydrolysis is analyzed with the aid of chemical thermodynamic computation. On the basis of this analysis, we modified the dye methylene blue with a rationally designed urea bond to specifically create a probe, called MB1, for rapid detection of tyrosinase. Our experimental results demonstrated that MB1 can serve as a highly sensitive near-infrared responsive fluorescent probe for the monitoring and bioimaging of tyrosinase. In addition, the activated MB1 probe can effectively kill melanoma cells by photodynamic therapy. Thus, the near-infrared probe has great potential for monitoring and treating melanoma

Environmental Risks of Nano Zerovalent Iron for Arsenate Remediation: Impacts on Cytosolic Levels of Inorganic Phosphate and MgATP^2– in <i>Arabidopsis thaliana</i>

The use of nano zerovalent iron (nZVI) for arsenate (As­(V)) remediation has proven effective, but full-scale injection of nZVI into the subsurface has aroused serious concerns for associated environmental risks. This study evaluated the efficacy of nZVI treatment for arsenate remediation and its potential hazards to plants using Arabidopsis thaliana grown in a hydroponic system. Biosensors for inorganic phosphate (Pi) and MgATP^2– were used to monitor <i>in vivo</i> Pi and MgATP^2– levels in plant cells. The results showed that nZVI could remove As­(V) from growth media, decrease As uptake by plants, and mitigate As­(V) toxicity to plants. However, excess nZVI could cause Pi starvation in plants leading to detrimental effects on plant growth. Due to the competitive adsorption of As­(V) and Pi on nZVI, removing As­(V) via nZVI treatment at an upstream site could relieve downstream plants from As­(V) toxicity and Pi deprivation, in which case 100 mg/L of nZVI was the optimal dosage for remediation of As­(V) at a concentration around 16.13 mg/L