[Functional Stability and Applicability of Heavy Metal Passivators in Reducing Cd Uptake by Lettuce].

The use of heavy metal passivators to prevent vegetables from absorbing heavy metals is an important measure to control heavy metal-polluted vegetable fields and to ensure the safe production of vegetables. A pot experiment of planting three times in succession was conducted to study the effects of Bacillus megaterium N3 (N3), rice husk biochar (BC), sheep manure organic fertilizer (SM), strain N3 combined with biochar (BC+N3), and strain N3 combined with sheep manure (SM+N3) on Cd uptake and the functional stability of lettuce using a heavy metal passivator only at the first planting. The comprehensive applicability of the passivation materials was evaluated by the dynamic weighted comprehensive function. The results showed that when lettuce was planted for the first time, compared with the control, all the heavy metal passivators could significantly reduce (61.2%-81%) the Cd content in the edible part of the lettuce. However, in the third cultivation of lettuce, only SM+N3 could significantly reduce the Cd uptake by lettuce, which indicated that SM+N3 had the best functional stability. The dynamic weighted comprehensive function was used to evaluate the Cd content in the edible part of fresh lettuce, available Cd content in the soil, yield, and remediation cost. The results showed that the comprehensive applicability of SM+N3 was the best, followed by that of SM, BC+N3, and BC, and the comprehensive evaluation effect of strain N3 was the worst. The results of this study provide a theoretical basis and technical support for remediation of heavy metal-contaminated vegetable fields.

Ratiometric near-infrared chemosensor for trivalent chromium ion based on tricarboyanine in living cells.

A tricarboyanine derivative (IRPP) is applied as a ratiometric near-infrared chemosensor for detecting trivalent chromium ions (Cr(3+)) in living cells. Upon the addition of Cr(3+) to a solution of IRPP, large-scale shifts in the emission spectrum (from 755 nm to 561 nm) are observed. In the newly developed sensing system, these well-resolved emission peaks yield a sensing system that covers a linear range from 1.0×10(-7) to 1.0×10(-5) M with a detection limit of 2.5×10(-8) M. The experimental results show the response behavior of IRPP towards Cr(3+) is pH independent under neutral conditions (6.0-7.5). Most importantly, the fast response time (less than 3 min) and selectivity for Cr(3+) over other common metal ions provide a strong argument for the use of this sensor in real world applications. As a proof of concept, the proposed chemosensor has been used to detect and quantify Cr(3+) in river water samples and to image Cr(3+) in living cells with encouraging results.

Detection and removal of Hg2+ based on mesoporous silica material functionalized by naphthalimide in aqueous solution.

An inorganic-organic silica material (SBA-15-1), prepared by immobilization of the naphthalimide derivative within the channels of the mesoporous silica material SBA-15, is characterized by several spectroscopic methods. SBA-15-1 can be used as a chemical sensor for detecting and removing Hg(2+) in a heterogeneous system. The fluorescence enhancement of SBA-15-1 was attributed to the formation of a complex between SBA-15-1 and Hg(2+) by a 1:1 complex ratio with the photo-induced electron transfer (PET) being forbidden. The sensor can be applied to the quantification of Hg(2+) with a linear range covering from 1.0 × 10(-7) to 1.0 × 10(-5) M under the neutral condition. Most importantly, the fluorescence changes of the sensor are remarkably specific for Hg(2+) in the presence of other metal ions. Moreover, the response of the sensor toward Hg(2+) is fast and chemically reversible. In addition, the sensor has been used for the determination of Hg(2+) in environmental samples with satisfactory results.

A fluorescent chemosensor for Hg2+ based on a rhodamine derivative in an aqueous solution.

In this paper, we unveil a novel rhodamine compound-based fluorescent chemosensor (compound 1) for fluorescent detection of Hg(2+) in an aqueous solution. The fluorescence enhancement of compound 1 was attributed to the formation of a complex between compound 1 and Hg(2+) by 1:1 complex ration (K = 8.0 × 10(4)), which has been utilized as the basis of fabrication of the Hg(2+)-sensitive chemosensor. A comparison of this method with some other fluorescence methods for the determination of Hg(2+) indicated that this method has high selectivity and good water solubility. The analytical performance characteristics of the proposed Hg(2+)-sensitive chemosensor were investigated. The chemosensor can be applied to the quantification of Hg(2+) with a linear range from 6.6 × 10(-7) to 2.4 × 10(-4) M and a detection limit of 1.3 × 10(-7) M. The experiment results show that the response behavior of compound 1 towards Hg(2+) is pH independent in neutral conditions (pH 5.0-9.0). Most importantly, the fluorescence changes of the chemosensor are remarkably specific for Hg(2+) in the presence of other metal ions, which meet the selective requirements for practical application. Moreover, the response of the chemosensor toward Hg(2+) is fast (response time less than 1 min). In addition, the chemosensor has been used for the determination of Hg(2+) in river water samples with satisfactory results.

A colormetric and fluorescent chemosensor for adenosine-5'-triphosphate based on rhodamine derivative.

A rhodamine spirolactam derivative (1) was developed as a colormetric and fluorescent chemosensor for adenosine-5'-triphosphate (ATP) via hydrogen bonds interaction. As far as we know, this is the first case to explore ATP-induced ring-opening of spirolactam in rhodamine derivatives. It exhibited a highly sensitive "turn-on" fluorescent response toward ATP with a 47-fold fluorescence intensity enhancement under 20 equiv. of ATP added. The chemosensor can be applied to the quantification of ATP with a linear range covering from 1.0×10(-7) to 2.0×10(-4) M and a detection limit of 2.5×10(-8) M. The experiment results show that the response behavior of 1 toward ATP is pH independent in medium condition (pH 6.0-8.0). Most importantly, the novel chemosensor has well solved the problem of serious interferences from other nucleoside polyphosphates such as ADP and AMP generally met by previously reported typical fluorescent chemosensors for ATP. Moreover, the response of the chemosensor toward ATP is fast (response time less than 3 min). In addition, the chemosensor can be used for the fluorescence assay for protein kinase activity with satisfactory results. The chemosensor for ATP based on hydrogen bonds interaction provided a novel strategy for the design of colormetric and ratiometric fluorescent probes for other target anions with high sensitivity and selectivity.

Colorimetric and fluorescent chemosensor for citrate based on a rhodamine and Pb2+ complex in aqueous solution.

In this paper we unveil a novel rhodamine compound based fluorescent chemosensor (1-Pb(2+)) for colormetric and fluorescent detection of citrate in aqueous solution. This is the first fluorescent chemosensor for citrate based on rhodamine compound. The comparison of this method with some other fluorescence methods for citrate indicates that the method can detect citrate in aqueous solution by both color changes and fluorescent changes with long emission wavelength. In the new developed sensing system, 1-Pb(2+) is fluorescent due to Pb(2+)-induced fluorescence enhancement of 1. However, the addition of citrate may release 1 into the solution with quenching of fluorescence. The chemosensor can be applied to the quantification of citrate with a linear range covering from 1.0×10(-7) to 5.0×10(-5) M and a detection limit of 2.5×10(-8) M. The experiment results show that the response behavior of 1-Pb(2+) towards citrate is pH independent in medium condition (pH 6.0-8.0). Most importantly, the fluorescence changes of the chemosensor are remarkably specific for citrate in the presence of other anions (even those that exist in high concentration), which meet the selective requirements for practical application. Moreover, the response of the chemosensor toward citrate is fast (response time less than 1 min). In addition, the chemosensor has been used for determination of citrate in urine samples with satisfactory results.