Detection of trace arsenic in drinking water: challenges and opportunities for microfluidics
08 Jul 2015-Vol. 1, Iss: 4, pp 426-447
TL;DR: In this article, the authors highlight the need for better portable arsenic contamination detection, and describe how microfluidic technology may be developed to address this need, and comment on their potential for portable microfluidity adaptation.
Abstract: Arsenic contamination of drinking water is a major global problem, with contamination in Bangladesh deemed most serious. Although the current World Health Organisation (WHO) maximum contamination limit (MCL) for arsenic in drinking water is 10 μg L−1, due to practical and economic constraints, the standard limit in Bangladesh and many other developing nations is 50 μg L−1. We propose that an ideal arsenic sensor, designed for routine monitoring, will have five essential qualities: sensitivity and selectivity for arsenic; speed and reliability; portability and robustness; reduced health and environmental risks; and affordability and ease of use for local technicians. It is our opinion that many of these characteristics can be accentuated by microfluidic systems. We describe candidate colorimetric, electrochemical, biological, electrophoretic, surface-sensing, and spectroscopic methods for arsenic detection; and comment on their potential for portable microfluidic adaptation. We also describe existing developments in the literature towards the ultimate creation of microfluidic total analysis systems (μTASs) for arsenic detection. The fundamental purpose of this review is to highlight the need for better portable arsenic contamination detection, and describe how microfluidic technology may be developed to address this need.
Citations
More filters
TL;DR: A colorimetric method based on 1,5-diphenylcarbazide dye for incorporation into a microfluidic detection system and rapid colour development was observed after the addition of the dye and samples were measured at 543 nm.
Abstract: Chromium contamination of drinking water has become a global problem due to its extensive use in industry. The most commonly used methods for chromium detection in water are laboratory-based methods, such as atomic absorption spectroscopy and mass spectroscopy. Although these methods are highly selective and sensitive, they require expensive maintenance and highly trained staff. Therefore, there is a growing demand for cost effective and portable detection methods that would meet the demand for mass monitoring. Microfluidic detection systems based on optical detection have great potential for onsite monitoring applications. Furthermore, their small size enables rapid sample throughput and minimises both reagent consumption and waste generation. In contrast to standard laboratory methods, there is also no requirement for sample transport and storage. The aim of this study is to optimise a colorimetric method based on 1,5-diphenylcarbazide dye for incorporation into a microfluidic detection system. Rapid colour development was observed after the addition of the dye and samples were measured at 543 nm. Beer’s law was obeyed in the range between 0.03–3 mg·L−1. The detection limit and quantitation limit were found to be 0.023 and 0.076 mg·L−1, respectively.
98 citations
Cites methods from "Detection of trace arsenic in drink..."
...Colorimetric methods can be implemented using simple and low-cost detection systems based on light emitting diodes (LEDs) as light source and photodiode detectors, making them suitable for use in portable microfluidic detection systems [50]....
[...]
TL;DR: The bimodal strategy offers obvious advantages including a label-free step, convenient operation, on-site assay, low cost, and high sensitivity, which is promising for reliable detection of arsenate and total arsenic in environmental samples.
Abstract: This study reports a novel and convenient bimodal method for label-free and signal-off detection of arsenate in environmental samples. Cobalt oxyhydroxide (CoOOH) nanoflakes with facile preparation and intrinsic peroxidase-like activity as nanozyme can efficiently catalyze the conversion of chromogenic substrate such as 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) with the presence of H2O2 into green-colored oxidation products. CoOOH nanoflakes can specifically bind with arsenate via electrostatic attraction and As-O bond interaction, which gives rise to inhibition of the peroxidase-like activity of CoOOH. Thus, through arsenate specific inhibition of CoOOH nanozyme toward ABTS catalysis, a simple colorimetric method was developed for arsenate detection with a detection limit of 3.72 ppb. Based on the system of CoOOH nanozyme and ABTS substrate, this colorimetric method can be converted into an electrochemical sensor for arsenate assay by the utilization of CoOOH nanoflake-modified electrode. The electrochemical measurement can be realized by chronoamperometry, which showed more sensitive and a lower limit of detection as low as 56.1 ppt. The applicability of this bimodal method was demonstrated by measuring arsenate and total arsenic in different real samples such as natural waters and soil extracted solutions, and the results are of satisfactory accuracy as confirmed by inductively coupled plasma mass spectrometry analysis. The bimodal strategy offers obvious advantages including a label-free step, convenient operation, on-site assay, low cost, and high sensitivity, which is promising for reliable detection of arsenate and total arsenic in environmental samples.
88 citations
TL;DR: Attention is called for to the gap between aptamer selection and biosensor design, and the gap needs to be carefully filled by careful binding assays to further the growth of the aptamer field.
Abstract: An arsenic-binding aptamer named Ars-3 was reported in 2009, and it has been used for detection of As(III) in more than two dozen papers. In this work, we performed extensive binding assays using isothermal titration calorimetry, various DNA-staining dyes, and gold nanoparticles. By carefully comparing Ars-3 and a few random control DNA sequences, no specific binding of As(III) was observed in each case. Therefore, we conclude that Ars-3 cannot bind As(III). Possible reasons for some of the previously reported binding and detection were speculated to be related to the adsorption of As(III) onto gold surfaces, which were used in many related sensor designs, and As(III)/Au interactions were not considered before. The selection data in the original paper were then analyzed in terms of sequence alignment, secondary structure prediction, and dissociation constant measurement. These steps need rigorous testing before confirming specific binding of newly selected aptamers. This study calls for attention to the gap between aptamer selection and biosensor design, and the gap needs to be filled by careful binding assays to further the growth of the aptamer field.
75 citations
TL;DR: This sensing platform can be developed as a universal approach for the fast, sensitive, and accurate detection of aptamer-binding molecules.
Abstract: A highly sensitive fluorescence biosensing system was designed for the detection of trace amounts of arsenic(III) (As3+) based on target-triggered successive signal amplification strategy. The specific recognition between the target As3+ and the aptamer sequence results in the release of the blocking DNA to trigger the subsequent signal amplification steps. Exonuclease III (Exo III)-mediated DNA recycling digest process is introduced into the sensing system to generate numerous Mg2+-dependent DNAzymes. After magnetic separation, the active DNAzyme with multiple turnovers could catalyze the continuous cleavage of the fluorophore-quencher-functionalized substrate strands, thus yielding a significantly amplified fluorescence signal for target detection. Due to the synergetic signal amplification of Exo III and DNAzyme, the fluorescent biosensor exhibits ultrasensitivity for As3+ monitoring, with a detection limit of 2 pM. Our established biosensor also displays excellent selectivity toward the target As3+ an...
56 citations
TL;DR: In this article, a simple, environment friendly and cost effective colorimetric approach for selective detection of arsenic (III) in aqueous medium was reported, where PEG functionalized silver nanoparticles were synthesized by chemical reduction method and applied for detection of heavy metal ions.
Abstract: Arsenic is well known for its toxicity and various health effects. In this work, we report a simple, environment friendly and cost effective colorimetric approach for selective detection of arsenic (III) in aqueous medium. PEG functionalized silver nanoparticles were synthesized by chemical reduction method and applied for detection of heavy metal ions like arsenic(III), cobalt (II), cadmium (II), copper (II), iron (III), lead (II), mercury (II), magnesium (II) and nickel (II). In case of arsenic samples, we have observed perceptible alteration of colors from yellow to bluish due to aggregation of PEG functionalized silver nanoparticles. Absorption spectra of the arsenic samples were measured through UV–Vis spectrometry to derive detectable range of arsenic (III) concentration. The results have showed that the detection limit of this sensing unit is 1 ppb with an excellent linearity of ∼0.99.
55 citations
References
More filters
TL;DR: In this article, surface-enhanced Raman scattering was used to detect single molecules and single nanoparticles at room temperature with the use of surface enhanced Raman, and the intrinsic Raman enhancement factors were on the order of 10 14 to 10 15, much larger than the ensemble-averaged values derived from conventional measurements.
Abstract: Optical detection and spectroscopy of single molecules and single nanoparticles have been achieved at room temperature with the use of surface-enhanced Raman scattering. Individual silver colloidal nanoparticles were screened from a large heterogeneous population for special size-dependent properties and were then used to amplify the spectroscopic signatures of adsorbed molecules. For single rhodamine 6G molecules adsorbed on the selected nanoparticles, the intrinsic Raman enhancement factors were on the order of 10 14 to 10 15 , much larger than the ensemble-averaged values derived from conventional measurements. This enormous enhancement leads to vibrational Raman signals that are more intense and more stable than single-molecule fluorescence.
9,609 citations
TL;DR: The manipulation of fluids in channels with dimensions of tens of micrometres — microfluidics — has emerged as a distinct new field that has the potential to influence subject areas from chemical synthesis and biological analysis to optics and information technology.
Abstract: The manipulation of fluids in channels with dimensions of tens of micrometres--microfluidics--has emerged as a distinct new field. Microfluidics has the potential to influence subject areas from chemical synthesis and biological analysis to optics and information technology. But the field is still at an early stage of development. Even as the basic science and technological demonstrations develop, other problems must be addressed: choosing and focusing on initial applications, and developing strategies to complete the cycle of development, including commercialization. The solutions to these problems will require imagination and ingenuity.
8,260 citations
TL;DR: The scale of the problem in terms of population exposed to high As concentrations is greatest in the Bengal Basin with more than 40 million people drinking water containing ‘excessive’ As as mentioned in this paper.
6,741 citations
Book•
01 Jan 1986
TL;DR: General methods bacterial strains and cloning vectors enzymes that modify DNA and RNA in vitro amplification of DNA using the polymerase chain reaction (PCR) and the thermostable Taq DNA polymerase, introduction DNA restriction fragment analysis and preparation.
Abstract: General methods bacterial strains and cloning vectors enzymes that modify DNA and RNA in vitro amplification of DNA using - the polymerase chain reaction (PCR) and the thermostable Taq DNA polymerase, introduction DNA restriction fragment analysis and preparation, introduction in vitro labeling of probes and filter hybridization plasmid DNA preparation for E. Coli hosts preparation of DNA from Lambda bacteriophage clones subcloning fragments into plasmid vectors and plasmid construction preparation of genomic DNA preparation and analysis of RNA from eukaryotic cells - overview geonomic cloning generatino of cDNA libaries preparation of subtractive cDNA, introduction chain termination sequencing transfection of mammalian cells, introduction basic methods of protein analysis in situ hybridization transgenic mouse preparation detection and in vitro generation of specific mutations in genes and cDNAs, introduction appendices.
4,526 citations
TL;DR: In this paper, a modular construction of a miniaturized "total chemical analysis system" is proposed, and theoretical performances of such systems based on flow injection analysis, chromatography and electrophoresis are compared with those of existing chemical sensors and analysis systems.
Abstract: Following the trend towards smaller channel inner diameter for better separation performance and shorter channel length for shorter transport time, a modular construction of a miniaturized 'total chemical analysis system' is proposed. The theoretical performances of such systems based on flow injection analysis, chromatography and electrophoresis, are compared with those of existing chemical sensors and analysis systems.
3,017 citations