Solution-based nanosensors for in-field detection with the naked eye

Abstract

This version is available at https://strathprints.strath.ac.uk/52490/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output.Journal Name Nanomaterials are revolutionising analytical applications with low-cost tests that enable detecting a target molecule in a few steps and with the naked eye. With this approach, nonexperts can perform analyses on-site and without utilising electronic readers. This is advantageous in point-of-care diagnostics, in-field measurements and analyses performed in resource-constrained settings. Here we review the main strategies adopted for detecting analytes with the naked eye and at the point of need using plasmonic nanosensors, catalytic nanoparticles and fluorescent nanomaterials. Examples of the detection of ions, glucose, small molecules, peptides and proteins with the nanosensors are explained in detail. IntroductionThe design of sensors for in-field measurements has been a central issue of analytical chemistry for decades. From the diagnosis of diseases at the point of care 1 to the detection of hazardous levels of pollutants 2,3 and the identification of pathogens in food samples, 4,5 there is a growing need for obtaining accurate information about the composition of a sample rapidly and at the point of need. For many years electrochemical sensors have dominated the area of in-field sensing due to the possibility of fabricating all the elements of the sensor with well-known microfabrication techniques. 6,7 These fabrication methods generate portable, compact devices in which the transducers are directly integrated with the circuitry. 8,9 However, although microchips containing electrochemical transducers can be mass-produced, the manufacturing cost of these devices is still too high for certain applications in which the sensor cannot be reutilised or recycled. Electrical readers are also expensive, and therefore their utilisation can only be justified in routine tests, for example in diagnostic tests r...

Microemulsification-based method: analysis of ethanol in fermentation broth of sugar cane

“…Such methods enable cheap, rapid, portable, and user-friendly assays, bypassing the need for qualied operators. 6,9 Moreover, such methods generate somewhat poor precision regarding the sensitivity and specicity, 10 because different paper substrates are employed to construct the device, affecting the ow rates and interactions with analytes. This type of assay enhances the capacity to make fast decisions, presenting high social and economic implications in industry, environment, and medicine.…”

Microemulsification-Based Method: Coupling with Separation Technique

“…Furthermore, the analyses in solution surpass precisionrelated downsides when making the tests on substrates such as paper [6,9]. In this case, the diverse paper substrates that are employed to fabricate the devices affect the flow rates and interactions with analytes [10]. This paper reports further investigations and application of the microemulsification-based method (MEC), a point-of-use platform that was recently proposed by these authors [11].…”

“…It relies on solutionbased-detection with naked eyes. In contrast with colorimetric tools [10], MEC response depends on colloid thermodynamics by relying on effect of analyte on the entropy of emulsions or Winsor systems. It changes the formation of thermodynamically stable dispersions, the microemulsions (MEs).…”

“…The generation of nanodroplets in MEs (transparent) allows the naked eye detection of Φ ME by monitoring the change of turbidity from the emulsions or Winsor systems (cloudy) as shown in Figure 1a. This cloudy-to-transparent conversion acts like a turning point in titrations, ensuring the visual measurement of Φ ME and, therefore, not only screening analyses (positive/negative data) as the most of naked eye colorimetry platforms [10] as well as precise quantitative analyses [11]. The response in colorimetry changes with the intensity of colour or tonality.…”

“…One potential output to perform point-of-use analyses is the accomplishment of the tests in solution with naked eye detection using disposable systems. It allows the determination of different analytes from the use of modified nanomaterial [10]. Naked eye methods bypasses the use of instrumental readers, an essential feature for in-situ technologies.…”