Abstract
The development of disposable sensors that can be easily adapted to every analytical problem is currently a hot topic that is revolutionizing many areas of science and technology. The need for decentralized analytical measurements at real time is increasing for solving problems in areas such as environment pollution, medical diagnostic, food quality assurance, etc., requiring fast action. Despite some current limitations of these devices, such as insufficient detection capability at (ultra)trace level and risk of interferent effects due to matrix, they allow low-cost analysis, portability, low sample consumption, and fast response. In the last years, development of paper-based analytical devices has undergone a dramatic increase for on-site detection of toxic metal ions and other pollutants. Along with the great availability of cellulose substrates, the immobilization of receptors providing enhanced recognition ability, such as a variety of nanomaterials, has driven the design of novel sensing approaches. This review is aimed at describing and discussing the different possibilities arisen with the use of different nanoreceptors (e.g., plasmonic nanoparticles, quantum dots, carbon-based fluorescent nanoparticles, etc.) immobilized onto cellulose-based substrates for trace element detection, their advantages and shortcomings.
Highlights
Conventional analytical methodology using equipment in central labs is well established but a number of stages such as sampling, sample preparation, and optimization of instrumental parameters need to be accomplished before analytical information can be obtained
Despite the abovementioned advantages accounting for the sharp increase in the development of paper-based assay devices (PADs) and microPADs for determining trace element analysis in environmental samples, lack of enough sensitivity to fulfil most drinking water guidelines is a main drawback, something that could be alleviated by further progress in three areas (Figure 1), i.e., introduction of receptors providing enhanced response, optimized designs, and integration with preconcentration approaches, as will be discussed in this review
Two shortcomings of PADs are addressed in this paper, i.e., the ‘coffee ring’ effect, which impairs the uniform distribution of the analyte on the cellulose substrate and the high absorbent capacity of common filter paper (Whatman) which facilitates penetration of the sample through the surface, thereby decreasing color intensity
Summary
Conventional analytical methodology using equipment in central labs is well established but a number of stages such as sampling, sample preparation, and optimization of instrumental parameters need to be accomplished before analytical information can be obtained. Despite the abovementioned advantages accounting for the sharp increase in the development of PADs and microPADs for determining trace element analysis in environmental samples, lack of enough sensitivity to fulfil most drinking water guidelines is a main drawback, something that could be alleviated by further progress in three areas (Figure 1), i.e., introduction of receptors providing enhanced response (e.g., nanostructured receptors), optimized designs, and integration with preconcentration approaches, as will be discussed in this review. The role played paper-based analytical devicesdigital as sensing platforms fordrive trace elethe design of green, miniaturized, low cost, and easy-to-use technologies for detection of ments using different transduction systems has been discussed in both general reviews elemental species. As;group the group of other anions includes iodate, iodide, cyanide, fluoride, sulphate, sulphite, chloride, and sulphide
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