Recent advances in chemical sensors for soil analysis: a review

The continuously rising interest in chemical sensors' applications in environmental monitoring, for soil analysis in particular, is owed to the sufficient sensitivity and selectivity of these analytical devices, their low costs, their simple measurement setups, and the possibility to perform online and in-field analyses with them. In this review the recent advances in chemical sensors for soil analysis are summarized. The working principles of chemical sensors involved in soil analysis; their benefits and drawbacks; and select applications of both the single selective sensors and multisensor systems for assessments of main plant nutrition components, pollutants, and other important soil parameters (pH, moisture content, salinity, exhaled gases, etc.) of the past two decades with a focus on the last 5 years (from 2017 to 2021) are overviewed

Application of Paper-Based Microfluidic Analytical Devices (µPAD) in Forensic and Clinical Toxicology: A Review

The need for providing rapid and, possibly, on-the-spot analytical results in the case of intoxication has prompted researchers to develop rapid, sensitive, and cost-effective methods and analytical devices suitable for use in nonspecialized laboratories and at the point of need (PON). In recent years, the technology of paper-based microfluidic analytical devices (μPADs) has undergone rapid development and now provides a feasible, low-cost alternative to traditional rapid tests for detecting harmful compounds. In fact, μPADs have been developed to detect toxic molecules (arsenic, cyanide, ethanol, and nitrite), drugs, and drugs of abuse (benzodiazepines, cathinones, cocaine, fentanyl, ketamine, MDMA, morphine, synthetic cannabinoids, tetrahydrocannabinol, and xylazine), and also psychoactive substances used for drug-facilitated crimes (flunitrazepam, gamma- hydroxybutyric acid (GHB), ketamine, metamizole, midazolam, and scopolamine). The present report critically evaluates the recent developments in paper-based devices, particularly in detection methods, and how these new analytical tools have been tested in forensic and clinical toxicology, also including future perspectives on their application, such as multisensing paper-based devices, microfluidic paper-based separation, and wearable paper-based sensors

Colorimetric paper-based sensors against cancer biomarkers

Cancer is a major cause of mortality and morbidity worldwide. Detection and quantification of cancer biomarkers plays a critical role in cancer early diagnosis, screening, and treatment. Clinicians, particularly in developing countries, deal with high costs and limited resources for diagnostic systems. Using low-cost substrates to develop sensor devices could be very helpful. The interest in paper-based sensors with colorimetric detection increased exponentially in the last decade as they meet the criteria for point-of-care (PoC) devices. Cellulose and different nanomaterials have been used as substrate and colorimetric probes, respectively, for these types of devices in their different designs as spot tests, lateral-flow assays, dipsticks, and microfluidic paper-based devices (μPADs), offering low-cost and disposable devices. However, the main challenge with these devices is their low sensitivity and lack of efficiency in performing quantitative measurements. This review includes an overview of the use of paper for the development of sensing devices focusing on colorimetric detection and their application to cancer biomarkers. We highlight recent works reporting the use of paper in the development of colorimetric sensors for cancer biomarkers, such as proteins, nucleic acids, and others. Finally, we discuss the main advantages of these types of devices and highlight their major pitfalls.This research was funded by Portuguese Foundation for Science and Technology (FCT), under the scope of the strategic funding of UIDB/04469/2020 unit and through Mariana Carneiro PhD grant reference SFRH/BD/131959/2017.info:eu-repo/semantics/publishedVersio

Colorimetric Paper-Based Sensors against Cancer Biomarkers

Cancer is a major cause of mortality and morbidity worldwide. Detection and quantification of cancer biomarkers plays a critical role in cancer early diagnosis, screening, and treatment. Clinicians, particularly in developing countries, deal with high costs and limited resources for diagnostic systems. Using low-cost substrates to develop sensor devices could be very helpful. The interest in paper-based sensors with colorimetric detection increased exponentially in the last decade as they meet the criteria for point-of-care (PoC) devices. Cellulose and different nanomaterials have been used as substrate and colorimetric probes, respectively, for these types of devices in their different designs as spot tests, lateral-flow assays, dipsticks, and microfluidic paper-based devices (μPADs), offering low-cost and disposable devices. However, the main challenge with these devices is their low sensitivity and lack of efficiency in performing quantitative measurements. This review includes an overview of the use of paper for the development of sensing devices focusing on colorimetric detection and their application to cancer biomarkers. We highlight recent works reporting the use of paper in the development of colorimetric sensors for cancer biomarkers, such as proteins, nucleic acids, and others. Finally, we discuss the main advantages of these types of devices and highlight their major pitfalls.This research was funded by Portuguese Foundation for Science and Technology (FCT), under the scope of the strategic funding of UIDB/04469/2020 unit and through Mariana Carneiro PhD grant reference SFRH/BD/131959/2017.info:eu-repo/semantics/publishedVersio

Colorimetric and fluorescent sensing of copper ions in water through o-phenylenediamine-derived carbon dots

Fluorescent nitrogen and sulfur co-doped carbon dots (NSCDs) were synthesized using a simple one-step hydrothermal method starting from o-phenylenediamine (OPD) and ammonium sulfide. The prepared NSCDs presented a selective dual optical response to Cu(II) in water through the arising of an absorption band at 660 nm and simultaneous fluorescence enhancement at 564 nm. The first effect was attributed to formation of cuprammonium complexes through coordination with amino functional groups of NSCDs. Alternatively, fluorescence enhancement can be explained by the oxidation of residual OPD bound to NSCDs. Both absorbance and fluorescence showed a linear increase with an increase of Cu(II) concentration in the range 1-100 mu M, with the lowest detection limit of 100 nM and 1 mu M, respectively. NSCDs were successfully incorporated in a hydrogel agarose matrix for easier handling and application to sensing. The formation of cuprammonium complexes was strongly hampered in an agarose matrix while oxidation of OPD was still effective. As a result, color variations could be perceived both under white light and UV light for concentrations as low as 10 mu M. Since these color changes were similarly perceived in tap and lake water samples, the present method could be a promising candidate for simple, cost-effective visual monitoring of copper onsite

Flexible and highly stabel electrospun nanofibrous membrane incorporating gold nanocluster as a efficient probe for visual colorimetric detection of Hg(II)

Cataloged from PDF version of article.Here, we describe the visual colorimetric detection of Hg2+ based on a flexible fluorescent electrospun nanofibrous membrane (NFM). It is an efficient approach, in which we have effectively integrated fluorescent gold nanoclusters (AuNC) into electrospun polyvinyl alcohol nanofibers. Interestingly, the resulting composite nanofibers (AuNC*NFM) are shown to retain the fluorescence properties of AuNC and exhibit red fluorescence under UV light, being cogent criteria for the production of a visual colorimetric sensor. Furthermore, capabilities with regard to the stability of the AuNC*NFM have been under observation for a period of six months, with conditions matching those of typical atmosphere, and the resulting outcome has thrown light on their long-term storability and usability. It is clear, from the fact that the nanofibrous membrane preserves the fluorescence ability up to a temperature of 100 °C, that temperature does not have an effect on the sensing performance in real-time application. The water-insoluble AuNC*NFM have been successfully tailored by cross-linking with glutaraldehyde vapor. Further, the contact mode approach has been taken into consideration for the visual fluorescent response to Hg2+, and the observed change of color indicates the utility of the composite nanofibers for onsite detection of Hg2+ with a detection limit of 1 ppb. The selectivity of the AuNC*NFM hybrid system has been analyzed by its response to other common toxic metal interferences (Pb2+, Mn2+, Cu2+, Ni2+, Zn2+, Cd2+) in water. Several unique features of the hybrid system have been determined, including high stability, self-standing ability, naked-eye detection, selectivity, reproducibility and easy handling – setting a new trend in membrane-based sensor systems

Colorimetric and Fluorescent Sensing of Copper Ions in Water through o-Phenylenediamine-Derived Carbon Dots

Funding Information: This work was supported by Regione Lazio through Progetto di Ricerca POR FESR LAZIO 2014–2020 Id: A0375-2020-36403 according to G09493 del 14 July 2021. M.A. has been supported by MIUR—Ministero dell’Istruzione Ministero dell’Università e della Ricerca (Ministry of Education, University and Research) under the national project FSE/FESR–PON Ricerca e Innovazione 2014–2020 (N° AIM1887574, CUP: E18H19000350007). This research was also supported by Fundação para a Ciência e Tecnologia, FCT/MCTES, through the Associate Laboratory for Green Chemistry—LAQV (grants UIDB/50006/2020 and UIDP/50006/2020). Publisher Copyright: © 2023 by the authors.Fluorescent nitrogen and sulfur co-doped carbon dots (NSCDs) were synthesized using a simple one-step hydrothermal method starting from o-phenylenediamine (OPD) and ammonium sulfide. The prepared NSCDs presented a selective dual optical response to Cu(II) in water through the arising of an absorption band at 660 nm and simultaneous fluorescence enhancement at 564 nm. The first effect was attributed to formation of cuprammonium complexes through coordination with amino functional groups of NSCDs. Alternatively, fluorescence enhancement can be explained by the oxidation of residual OPD bound to NSCDs. Both absorbance and fluorescence showed a linear increase with an increase of Cu(II) concentration in the range 1–100 µM, with the lowest detection limit of 100 nM and 1 µM, respectively. NSCDs were successfully incorporated in a hydrogel agarose matrix for easier handling and application to sensing. The formation of cuprammonium complexes was strongly hampered in an agarose matrix while oxidation of OPD was still effective. As a result, color variations could be perceived both under white light and UV light for concentrations as low as 10 µM. Since these color changes were similarly perceived in tap and lake water samples, the present method could be a promising candidate for simple, cost-effective visual monitoring of copper onsite.publishersversionpublishe

New Methods for the Optical Detection of Trace Compounds and the Delivery of a Chemical Oxidant

Biogenic amines are known indicators of spoilage in food. Indole in particular is a chemical used extensively to indicate seafood freshness. Levels higher than 25 μg [micrograms]/100 g shrimp mark early decomposition, according to the US Food and Drug Administration. We developed an optical probe based on an Ehrlich-type reaction to detect indole in shrimp. The probe is based on the reaction of p-dimethylaminobenzaldhyde (DMAB) with indole, generating red β[beta]-bis(indolyl)methane (BIM). Color development is observed by the naked eye after exposure to indole. When using UV-Visible spectroscopy as a detection method, the limits of detection and quantification are of 0.05 and 0.16 μg mL-1 [per milliliter], respectively. These limits lead to quantification of less than 25 μg [micrograms] indole/100 g shrimp, when recovery is accounted for. Moreover, an inexpensive handheld colorimeter can be used to perform optical measurements of indole by the probe with similar sensitivity. In addition, studies to confirm the structure of BIM were conducted. The β-position of two indole molecules is involved in the reaction with one DMAB molecule, yielding the product β[beta]-bis(indolyl)methane (BIM).Determination of amines in aviation fuels is of interest as these species reduce fuel stability when present in higher concentrations. Since anilines and indoles are species of major presence in fuels, we have explored their simultaneous determination by the probe using a chemometric calibration with Classical Least Squares and Principal Component Regression.In-situ chemical oxidation (ISCO) is an approach for remediation of polluted groundwater by the release of oxidants directly into the contaminated zone. We have developed a system for the controlled release of potassium persulfate from pellets of diatomaceous earth for the oxidation of organic contaminants, obtaining a continuous delivery for up to 21 h. In addition, this approach was used to release Fe2+ [iron two plus] ions for in-situ activation of persulfate. Controlled-released persulfate and Fe2+ ions from the pellets have been used for batch treatment of 15 mg L-1 [per liter] trichloroethylene (TCE) aqueous solution, giving residual TCE concentration of \u3c [less than] 0.06 mg L-1 after 6 h and degradation of 93% TCE after 2 h

Nanomaterials for Healthcare Biosensing Applications

In recent years, an increasing number of nanomaterials have been explored for their applications in biomedical diagnostics, making their applications in healthcare biosensing a rapidly evolving field. Nanomaterials introduce versatility to the sensing platforms and may even allow mobility between different detection mechanisms. The prospect of a combination of different nanomaterials allows an exploitation of their synergistic additive and novel properties for sensor development. This paper covers more than 290 research works since 2015, elaborating the diverse roles played by various nanomaterials in the biosensing field. Hence, we provide a comprehensive review of the healthcare sensing applications of nanomaterials, covering carbon allotrope-based, inorganic, and organic nanomaterials. These sensing systems are able to detect a wide variety of clinically relevant molecules, like nucleic acids, viruses, bacteria, cancer antigens, pharmaceuticals and narcotic drugs, toxins, contaminants, as well as entire cells in various sensing media, ranging from buffers to more complex environments such as urine, blood or sputum. Thus, the latest advancements reviewed in this paper hold tremendous potential for the application of nanomaterials in the early screening of diseases and point-of-care testing

Synthesis and applications in immunoassays of antibody-protected nanoclusters

187 p.Los nanoclusters (NCs) han ganado atención los últimos años debido a sus propiedades ópticas y químicas dependientes del tamaño. En esta tesis se presenta el primer método para la síntesis de NCs empleando anticuerpos como andamios estructurales y sus aplicaciones en inmunoensayos. Las síntesis se realizan empleando condiciones suaves que no alteran la estructura del anticuerpo, manteniendo su estructura secundaria y sus funciones biológicas. Así, los anticuerpos modificados con NCs mantienen la afinidad por su antígeno. Los NCs resultantes según su naturaleza pueden presentar propiedades fluorescentes y fotocatalíticas (CdS NCs) o catalíticas (Ag/Pt NCs y Au/Pt NCs).Estas propiedades se han empleado para dar los primeros pasos hacia el desarrollo de un inmunoensayo homogéneo competitivo basado en FRET empleando los CdS NCs-IgG fluorescentes como donantes de energía. Los NCs bimetálicos se han empleado como anticuerpo de detección en un inmunoensayo colorimétrico tipo sándwich y se ha comparado su rendimiento con el de la comúnmente empleada enzima HRP. Empleando NCs bimetálicos se ha conseguido mejorar el límite de detección 5 veces con los Ag/Pt NCs-IgG y hasta 56 veces empleando los Au/Pt NCs-IgG en comparación con el empleo de un anticuerpo de detección marcado con HRP