Research

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13 pages, 2069 KiB

Open AccessArticle

Highly Sensitive Detection of Chemically Modified Thio-Organophosphates by an Enzymatic Biosensing Device: An Automated Robotic Approach

by Giovanni Paolo Cetrangolo, Janis Rusko, Carla Gori, Paola Carullo, Giuseppe Manco, Marco Chino and Ferdinando Febbraio

Sensors 2020, 20(5), 1365; https://doi.org/10.3390/s20051365 - 02 Mar 2020

Cited by 11 | Viewed by 3471

Abstract

Pesticides represent some of the most common man-made chemicals in the world. Despite their unquestionable utility in the agricultural field and in the prevention of pest infestation in public areas of cities, pesticides and their biotransformation products are toxic to the environment and [...] Read more.

Pesticides represent some of the most common man-made chemicals in the world. Despite their unquestionable utility in the agricultural field and in the prevention of pest infestation in public areas of cities, pesticides and their biotransformation products are toxic to the environment and hazardous to human health. Esterase-based biosensors represent a viable alternative to the expensive and time-consuming systems currently used for their detection. In this work, we used the esterase-2 from Alicyclobacillus acidocaldarius as bioreceptor for a biosensing device based on an automated robotic approach. Coupling the robotic system with a fluorescence inhibition assay, in only 30 s of enzymatic assay, we accomplished the detection limit of 10 pmol for 11 chemically oxidized thio-organophosphates in solution. In addition, we observed differences in the shape of the inhibition curves determined measuring the decrease of esterase-2 residual activity over time. These differences could be used for the characterization and identification of thio-organophosphate pesticides, leading to a pseudo fingerprinting for each of these compounds. This research represents a starting point to develop technologies for automated screening of toxic compounds in samples from industrial sectors, such as the food industry, and for environmental monitoring. Full article

(This article belongs to the Special Issue Optical and Fluorescent Sensors for Environment)

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16 pages, 4226 KiB

Open AccessArticle

Molecular Dissection of dH3w, A Fluorescent Peptidyl Sensor for Zinc and Mercury

by Marialuisa Siepi, Rosario Oliva, Filomena Battista, Luigi Petraccone, Pompea Del Vecchio, Viviana Izzo, Fabrizio Dal Piaz, Rachele Isticato, Eugenio Notomista and Giuliana Donadio

Sensors 2020, 20(3), 598; https://doi.org/10.3390/s20030598 - 21 Jan 2020

Cited by 2 | Viewed by 1982

Abstract

Previously, we reported that fluorescent peptide dansyl-HPHGHW-NH₂ (dH3w), designed on the repeats of the human histidine-rich glycoprotein, shows a turn-on response to Zn(II) and a complex response to Hg(II) characterized by a turn-off phase at low Hg(II) concentrations and a turn-on phase [...] Read more.

Previously, we reported that fluorescent peptide dansyl-HPHGHW-NH₂ (dH3w), designed on the repeats of the human histidine-rich glycoprotein, shows a turn-on response to Zn(II) and a complex response to Hg(II) characterized by a turn-off phase at low Hg(II) concentrations and a turn-on phase at high concentrations. As Hg(II) easily displaces Zn(II), dH3w is a useful probe for the environmental monitoring of Hg(II). In order to investigate the molecular basis of the metal selectivity and fluorescence response, we characterized three variants, dH3w(H1A), dH3w(H3A), and dH3w(H5A), in which each of the three histidine residues was changed to alanine, and two variants with a single fluorescent moiety, namely dH3w(W6A), in which the tryptophan residue at the C-terminus was changed to alanine, and AcH3w, in which the N-terminal dansyl moiety was substituted by an acetyl group. These variants allowed us to demonstrate that all the histidine residues are essential for a strong interaction with Zn(II), whereas two histidine residues (in particular His5) and the dansyl group are necessary to bind Hg(II). The data reported herein shed light on the molecular behavior of dH3w, thus paving the way to the rational designing of further and more efficient fluorescent peptidyl probes for Hg(II). Full article

(This article belongs to the Special Issue Optical and Fluorescent Sensors for Environment)

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15 pages, 2080 KiB

Open AccessArticle

Predictions of Cu, Zn, and Cd Concentrations in Soil Using Portable X-Ray Fluorescence Measurements

by Karl Adler, Kristin Piikki, Mats Söderström, Jan Eriksson and Omran Alshihabi

Sensors 2020, 20(2), 474; https://doi.org/10.3390/s20020474 - 14 Jan 2020

Cited by 23 | Viewed by 3425

Abstract

Portable X-ray fluorescence (PXRF) measurements on 1520 soil samples were used to create national prediction models for copper (Cu), zinc (Zn), and cadmium (Cd) concentrations in agricultural soil. The models were validated at both national and farm scales. Multiple linear regression (MLR), random [...] Read more.

Portable X-ray fluorescence (PXRF) measurements on 1520 soil samples were used to create national prediction models for copper (Cu), zinc (Zn), and cadmium (Cd) concentrations in agricultural soil. The models were validated at both national and farm scales. Multiple linear regression (MLR), random forest (RF), and multivariate adaptive regression spline (MARS) models were created and compared. National scale cross-validation of the models gave the following R² values for predictions of Cu (R² = 0.63), Zn (R² = 0.92), and Cd (R² = 0.70) concentrations. Independent validation at the farm scale revealed that Zn predictions were relatively successful regardless of the model used (R² > 0.90), showing that a simple MLR model can be sufficient for certain predictions. However, predictions at the farm scale revealed that the non-linear models, especially MARS, were more accurate than MLR for Cu (R² = 0.94) and Cd (R² = 0.80). These results show that multivariate modelling can compensate for some of the shortcomings of the PXRF device (e.g., high limits of detection for certain elements and some elements not being directly measurable), making PXRF sensors capable of predicting elemental concentrations in soil at comparable levels of accuracy to conventional laboratory analyses. Full article

(This article belongs to the Special Issue Optical and Fluorescent Sensors for Environment)

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13 pages, 3518 KiB

Open AccessArticle

Hydrogel Fluorescence Microsensor with Fluorescence Recovery for Prolonged Stable Temperature Measurements

by Hairulazwan Hashim, Hisataka Maruyama, Yusuke Akita and Fumihito Arai

Sensors 2019, 19(23), 5247; https://doi.org/10.3390/s19235247 - 29 Nov 2019

Cited by 8 | Viewed by 3437

Abstract

This work describes a hydrogel fluorescence microsensor for prolonged stable temperature measurements. Temperature measurement using microsensors has the potential to provide information about cells, tissues, and the culture environment, with optical measurement using a fluorescent dye being a promising microsensing approach. However, it [...] Read more.

This work describes a hydrogel fluorescence microsensor for prolonged stable temperature measurements. Temperature measurement using microsensors has the potential to provide information about cells, tissues, and the culture environment, with optical measurement using a fluorescent dye being a promising microsensing approach. However, it is challenging to achieve stable measurements over prolonged periods with conventional measurement methods based on the fluorescence intensity of fluorescent dye because the excited fluorescent dye molecules are bleached by the exposure to light. The decrease in fluorescence intensity induced by photobleaching causes measurement errors. In this work, a photobleaching compensation method based on the diffusion of fluorescent dye inside a hydrogel microsensor is proposed. The factors that influence compensation in the hydrogel microsensor system are the interval time between measurements, material, concentration of photo initiator, and the composition of the fluorescence microsensor. These factors were evaluated by comparing a polystyrene fluorescence microsensor and a hydrogel fluorescence microsensor, both with diameters of 20 µm. The hydrogel fluorescence microsensor made from 9% poly (ethylene glycol) diacrylate (PEGDA) 575 and 2% photo initiator showed excellent fluorescence intensity stability after exposure (standard deviation of difference from initial fluorescence after 100 measurement repetitions: within 1%). The effect of microsensor size on the stability of the fluorescence intensity was also evaluated. The hydrogel fluorescence microsensors, with sizes greater than the measurement area determined by the axial resolution of the confocal microscope, showed a small decrease in fluorescence intensity, within 3%, after 900 measurement repetitions. The temperature of deionized water in a microchamber was measured for 5400 s using both a thermopile and the hydrogel fluorescence microsensor. The results showed that the maximum error and standard deviation of error between these two sensors were 0.5 °C and 0.3 °C, respectively, confirming the effectiveness of the proposed method. Full article

(This article belongs to the Special Issue Optical and Fluorescent Sensors for Environment)

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12 pages, 2178 KiB

Open AccessArticle

Determination of Picomolar Concentrations of Paraoxon in Human Urine by Fluorescence-Based Enzymatic Assay

by Giovanni Paolo Cetrangolo, Carla Gori, Janis Rusko, Sara Terreri, Giuseppe Manco, Amelia Cimmino and Ferdinando Febbraio

Sensors 2019, 19(22), 4852; https://doi.org/10.3390/s19224852 - 07 Nov 2019

Cited by 12 | Viewed by 3218

Abstract

Organophosphate (OP) pesticides are widely used in the agricultural field and in the prevention of pest infestation in private and public areas of cities. Despite their unquestionable utility, several of these compounds demonstrate toxic effects to the environment and human health. In particular, [...] Read more.

Organophosphate (OP) pesticides are widely used in the agricultural field and in the prevention of pest infestation in private and public areas of cities. Despite their unquestionable utility, several of these compounds demonstrate toxic effects to the environment and human health. In particular, the occurrence of some organophosphate pesticides is correlated to the incidence of nervous system disorders, especially in children. The detection of pesticide residues in the human body represents an important task to preserve human health. In our work we propose the use of esterase-based biosensors as a viable alternative to the expensive and time-consuming systems currently used for their detection in human fluids. Using the esterase-2 activity, coupled with a fluorescence inhibition assay, we are able to detect very low concentration levels of diethyl (4-nitrophenyl) phosphate (paraoxon) in the range of the femtomole (fmol). Method robustness tests indicate the stability of esterase-2 in a diluted solution of 4% human urine, and we are able to accurately determine concentration levels of paraoxon in the range from 0.1 to 2 picomoles (pmol). The system sensitivity for OP detection is calculated at 524 ± 14.15 fmol of paraoxon recognized at 10% of inhibition, with an estimated limit of quantification of 262 ± 8.12 pmol mL⁻¹. These values are comparable with the most recent analysis methods based on mass spectrometry carried out on human samples for pesticide detection. This research represents a starting point to develop cheap and fast testing methods for a rapid screening of toxic substances in human samples. Full article

(This article belongs to the Special Issue Optical and Fluorescent Sensors for Environment)

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12 pages, 3742 KiB

Open AccessArticle

Hydrazine-Selective Fluorescent Turn-On Probe Based on Ortho-Methoxy-Methyl-Ether (o-MOM) Assisted Retro-aza-Henry Type Reaction

by Yuna Jung, Nam Kyoo Park, Jae Seung Kang and Dokyoung Kim

Sensors 2019, 19(20), 4525; https://doi.org/10.3390/s19204525 - 17 Oct 2019

Cited by 12 | Viewed by 3307

Abstract

Hydrazine (N₂H₄) is one of the most widely used industrial chemicals that can be utilized as a precursor of pesticides, pharmaceutics, and rocket propellant. Due to its biological and environmental toxicity with potential health risks, various sensing tools have [...] Read more.

Hydrazine (N₂H₄) is one of the most widely used industrial chemicals that can be utilized as a precursor of pesticides, pharmaceutics, and rocket propellant. Due to its biological and environmental toxicity with potential health risks, various sensing tools have been developed. Among them, fluorescence-based molecular sensing systems have been highlighted due to its simple-operation, high selectivity and sensitivity, and biocompatibility. In our recent report, we disclosed a ratiometric type fluorescent probe, called HyP-1, for the detection of hydrazine, which is based on ortho-methoxy-methyl-ether (o-MOM) moiety assisted hydrazone-formation of the donor (D)-acceptor (A) type naphthaldehyde backbone. As our follow-up research, we disclose a turn-on type fluorescent probe, named HyP-2, as the next-generation hydrazine probe. The sensing rational of HyP-2 is based on the o-MOM assisted retro-aza-Henry type reaction. The dicyanovinyl moiety, commonly known as a molecular rotor, causes significant emission quenching of a fluorescent platform in aqueous media, and its cleavage with hydrazone-formation, which induces a significant fluorescence enhancement. The high selectivity and sensitivity of HyP-2 shows practical explicabilities, including real-time paper strip assay, vapor test, soil analysis, and real water assay. We believe its successful demonstrations suggest further applications into a wide variety of fields. Full article

(This article belongs to the Special Issue Optical and Fluorescent Sensors for Environment)

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Review

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28 pages, 7828 KiB

Open AccessReview

Perylene Diimide-Based Fluorescent and Colorimetric Sensors for Environmental Detection

by Shuai Chen, Zexu Xue, Nan Gao, Xiaomei Yang and Ling Zang

Sensors 2020, 20(3), 917; https://doi.org/10.3390/s20030917 - 09 Feb 2020

Cited by 54 | Viewed by 7219

Abstract

Perylene tetracarboxylic diimide (PDI) and its derivatives exhibit excellent thermal, chemical and optical stability, strong electron affinity, strong visible-light absorption and unique fluorescence on/off features. The combination of these features makes PDIs ideal molecular frameworks for development in a broad range of sensors [...] Read more.

Perylene tetracarboxylic diimide (PDI) and its derivatives exhibit excellent thermal, chemical and optical stability, strong electron affinity, strong visible-light absorption and unique fluorescence on/off features. The combination of these features makes PDIs ideal molecular frameworks for development in a broad range of sensors for detecting environmental pollutants such as heavy metal ions (e.g., Cu²⁺, Cd²⁺, Hg²⁺, Pd²⁺, etc.), inorganic anions (e.g., F⁻, ClO₄⁻, PO₄⁻, etc.), as well as poisonous organic compounds such as nitriles, amines, nitroaromatics, benzene homologues, etc. In this review, we provide a comprehensive overview of the recent advance in research and development of PDI-based fluorescent sensors, as well as related colorimetric and multi-mode sensor systems, for environmental detection in aqueous, organic or mixed solutions. The molecular design of PDIs and structural optimization of the sensor system (regarding both sensitivity and selectivity) in response to varying analytes are discussed in detail. At the end, a perspective summary is provided covering both the key challenges and potential solutions for the future development of PDI-based optical sensors. Full article

(This article belongs to the Special Issue Optical and Fluorescent Sensors for Environment)

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18 pages, 5826 KiB

Open AccessReview

Mechanochromic Fluorescent Polymers with Aggregation-Induced Emission Features

by Andrea Pucci

Sensors 2019, 19(22), 4969; https://doi.org/10.3390/s19224969 - 14 Nov 2019

Cited by 47 | Viewed by 5781

Abstract

Mechanochromic polymers are defined as materials that are able to detect a mechanical stress through an optical output. This feature has evoked a growing interest in the last decades, thanks to the progress of chromogenic molecules whose optical characteristics and chemical functionalities allow [...] Read more.

Mechanochromic polymers are defined as materials that are able to detect a mechanical stress through an optical output. This feature has evoked a growing interest in the last decades, thanks to the progress of chromogenic molecules whose optical characteristics and chemical functionalities allow their effective insertion in many thermoplastic and thermoset matrices. Among the different types of fluorogenic probes able to detect mechanical solicitations, those with aggregation-induced emission (i.e., AIEgens) have attracted tremendous interest since their discovery in 2001. In the present review, the main principles behind the AIEgens working behavior are introduced along with the current state of knowledge concerning the design and preparation of the derived mechanochromic fluorescent polymers. Examples are provided concerning the most ingenious solution for the preparation of chromogenic materials, starting from different types of commodity plastics or synthetic polymers and combined with the latest AIE technology to provide the most sensitive response to mechanical stress. Full article

(This article belongs to the Special Issue Optical and Fluorescent Sensors for Environment)

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