Fluorometric sensing of ultralow As(III) concentrations using Ag doped hollow CdS/ZnS bi-layer nanoparticles

Gold nanoparticles embedded Fe-BTC (AuNPs@Fe-BTC) metal-organic framework as a fluorescence sensor for the selective detection of As(III) in contaminated waters

In this article, a new off-mode fluorescent platform based on the metal-organic framework (MOF) is introduced as a highly selective and rapid chemical sensor for the detection of As(III) in water and wastewater samples. A typical Fe-BTC (BTC = 1,3,5-benzenetricarboxylate or trimesic acid) MOF was used as a porous template for loading gold nanoparticles (AuNPs@Fe-BTC MOF). The physicochemical properties of AuNPs@Fe-BTC MOF were characterized by Fourier-transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EAX), element mapping (MAP) and X-ray diffraction (XRD) analysis. This sensing method for As(III) ions is based on the fact that the fluorescence intensity of AuNPs@Fe-BTC MOF sensor decreases in proportion to the increase in As(III) concentration. The main effective factors on the performance of the sensor signal such as MOF dosage, sonication time, pH and reaction time were optimized. Under optimized conditions, the calibration graph was linear in the concentration range of 0.5-380 ng mL-1 of As(III) and the limit of detection was 0.2 ng mL-1. The proposed method was successfully validated by addition/recovery experiments by the determination of As(III) in four river water and two wastewater effluent samples.

Research Progress in Fluorescent Probes for Arsenic Species

Arsenic is a toxic non-metallic element that is widely found in nature. In addition, arsenic and arsenic compounds are included in the list of Group I carcinogens and toxic water pollutants. Therefore, rapid and efficient methods for detecting arsenic are necessary. In the past decade, a variety of small molecule fluorescent probes have been developed, which has been widely recognized for their rapidness, efficiency, convenience and sensitivity. With the development of new nanomaterials (AuNPs, CDs and QDs), organic molecules and biomolecules, the conventional detection of arsenic species based on fluorescence spectroscopy is gradually transforming from the laboratory to the portable kit. Therefore, in view of the current research status, this review introduces the research progress of both traditional and newly developed fluorescence spectrometry based on novel materials for arsenic detection, and discusses the potential of this technology in the rapid screening and field testing of water samples contaminated with arsenic. The review also discusses the problems that still exist in this field, as well as the expectations.

Carbon dots-MnO2 nanocomposites for As(III) detection in groundwater with high sensitivity and selectivity

As(iii) pollution has caused increasing concern due to its significant impact in environmental safety and human health. Carbon dots (CDs)-MnO2 nanocomposites were prepared and characterized for As(iii) detection. The intense blue fluorescence of CDs can be greatly quenched by functionalization with MnO2 nanosheets due to the existence of the fluorescence resonance energy transfer (FRET) effect. CDs-MnO2 nanocomposites were then used as a fluorescence sensor for As(iii) detection with high detection sensitivity and selectivity. The redox reaction between As(iii) and MnO2 nanosheets can induce the decomposition of MnO2 and termination of the FRET process. Then the blue fluorescence originating from CDs can be recovered. The detection limit of CDs-MnO2 nanocomposites toward As(iii) was calculated to be 16.8 nM (1.40 ppb) in a linear concentration range of 0-200 nM. CDs-MnO2 nanocomposites were also found to possess highly selective ability toward As(iii) detection. In addition, the spiked and recovery test also confirmed the practicality and reliability of CDs-MnO2 nanocomposites toward As(iii) detection in real water samples, such as groundwater etc. Our research has provided a reliable tool and strategy for visual detection of As(iii) with outstanding sensing ability.

Design of Fluorescence-Enhanced Silver Nanoisland Chips for High-Throughput and Rapid Arsenite Assay

High-throughput and rapid arsenite (As(III)) monitoring is an urgent task to deal with the critical threat from As(III) contamination in the environment. In this study, an effective, portable, and sensitive As(III) assay was developed using the plasmonic silver (pAg) chips for As(III) detection. The pAg chips were fabricated by a simple seed-mediated method to grow the silver nanoisland films (Ag-NIFs) with the compact nanoislands and adjustable interisland gaps on the large-sized substrates. With appropriate surface functionalization and optimal chip manufacturing, Cy7.5 fluorescence dye can be immobilized on the surface of Ag-NIFs in the presence of As(III) to output the enhanced fluorescence signals up to 10-fold and improve the detection limit of As(III) less than 10 ppb. According to our results, the high-throughput detection measurements and wide dynamic range over 4 orders of magnitude implied the broad prospects of pAg chips in fluorescence-enhanced assays. The proposed As(III) assay has shown great opportunities for the practical application of ultratrace As(III) monitoring.

Label-free gold nanorod-based plasmonic sensing of arsenic(iii) in contaminated water

An efficient label-free strategy for arsenic(iii) sensing in water through the suppression of iron(iii)-catalyzed oxidative shortening of gold nanorods.

Fluorometric selective detection of fluoride ions in aqueous media using Ag doped CdS/ZnS core/shell nanoparticles

In this study, a fluorometric method based on Ag–CdS/Ag–ZnS core/shell nanoparticles is developed for fluoride ion detection.