Research

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16 pages, 7881 KiB

Open AccessArticle

Quantitative Analysis of Meteorite Elements Based on the Multidimensional Scaling–Back Propagation Neural Network Algorithm Combined with Raman Mapping-Assisted Micro-Laser Induced Breakdown Spectroscopy

by Hongpeng Wang, Yingjian Xin, Peipei Fang, Yian Wang, Mingkang Duan, Wenming Wu, Ruidong Yang, Sicong Liu, Liang Zhang and Xiong Wan

Chemosensors 2023, 11(11), 567; https://doi.org/10.3390/chemosensors11110567 - 20 Nov 2023

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Abstract

Meteorites are an essential reference for human exploration of the universe and its cosmic evolution and an essential research object for searching for extraterrestrial life. Ways to quickly identify and screen suspected meteorite samples have become the foundation and prerequisite for research on [...] Read more.

Meteorites are an essential reference for human exploration of the universe and its cosmic evolution and an essential research object for searching for extraterrestrial life. Ways to quickly identify and screen suspected meteorite samples have become the foundation and prerequisite for research on high-value meteorite samples. Therefore, this paper proposes a Raman mapping-assisted micro-laser induced breakdown spectroscopy (micro-LIBS) technology for field detection of suspected meteorite material composition without sample pre-processing, with a high detection speed and cost-effectiveness, to realize the detection of element composition and molecular structure. Raman mapping carries out multispectral imaging with high spectral resolution of the region of interest. The fusion of Raman mapping and optical microscopy images can provide mineral categories and spatial distribution characteristics in regions of interest. A quantitative analysis model for Fe, Mg, and Na elements was constructed based on the multidimensional scaling–back propagation neural network (MDS-BPNN) algorithm. The determination coefficient of the model test set was better than 0.997, and the root mean square error was better than 0.65. The content of Fe, Mg, and Na elements in the meteorite was preliminarily evaluated, providing a reference for further analysis of element information in spectral image fusion data. The Raman–LIBS combined technology has significant application potential in rapidly evaluating suspected meteorite samples. Without high-end precision instruments or field research, this technology can provide scientists with significant reference value atomic and molecular spectral information. At the same time, this technology can be extended to other petrology research. We offer a fast, efficient, cost-effective, and reliable analysis scheme for reference. Full article

(This article belongs to the Special Issue Optical Chemical Sensors and Spectroscopy for Chemical Trace Element Detection)

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15 pages, 17524 KiB

Open AccessArticle

Rapid Determination of Meteorolite Composition Based on X-ray Phase Contrast Imaging-Assisted Raman Spectroscopy

by Hongpeng Wang, Peipei Fang, Yian Wang, Yingjian Xin, Shengjun Xiong, Sicong Liu, Yanling Xue, Liang Zhang and Xiong Wan

Chemosensors 2023, 11(11), 563; https://doi.org/10.3390/chemosensors11110563 - 12 Nov 2023

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Abstract

Returning extraterrestrial samples to Earth has become essential for future deep space exploration. Achieving a comprehensive evaluation of the physical and chemical properties of samples with minimal damage is key to analyzing extraterrestrial samples in the future, as well as to the future [...] Read more.

Returning extraterrestrial samples to Earth has become essential for future deep space exploration. Achieving a comprehensive evaluation of the physical and chemical properties of samples with minimal damage is key to analyzing extraterrestrial samples in the future, as well as to the future sampling and returning of heterogeneous solid samples. This article aims to reconstruct the three-dimensional internal structure of high-contrast objects, select sections of interest through internal structure and detail features, and then analyze the physical and chemical properties of the samples based on laser spectroscopy technology. This paper proposes a strategy based on Raman mapping and X-ray phase-contrast imaging technology to reconstruct the three-dimensional internal structure of a heterogeneous solid sample and detect the substance composition of the region of interest. This study takes meteorite samples as an example and uses X-ray phase-contrast imaging technology to distinguish and reconstruct the spatial distribution of different components in the meteorite, providing a three-dimensional visualization reference with a high spatial resolution for the spatial positioning of the region of interest. Raman spectroscopy, in combination with LIBS, was used to further identify the meteorite as pallasite and to achieve the spectral image fusion of high spatial and high spectral resolutions. The experimental results show that the unknown meteorite’s three-dimensional structure and its components’ spatial distribution can be evaluated based on Raman mapping combined with X-ray phase-contrast imaging technology. This article provides a highly valuable analytical strategy by which to analyze samples returned from deep space exploration. Full article

(This article belongs to the Special Issue Optical Chemical Sensors and Spectroscopy for Chemical Trace Element Detection)

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12 pages, 2868 KiB

Open AccessCommunication

Detection of a Nerve Agent Simulant by a Fluorescent Sensor Array

by Rossella Santonocito, Mario Spina, Roberta Puglisi, Andrea Pappalardo, Nunzio Tuccitto and Giuseppe Trusso Sfrazzetto

Chemosensors 2023, 11(9), 503; https://doi.org/10.3390/chemosensors11090503 - 15 Sep 2023

Cited by 2 | Viewed by 1610

Abstract

Detection of nerve agents (NAs) gas in the environment through portable devices to protect people in case of emergencies still remains a challenge for scientists involved in this research field. Current detection strategies require the use of cumbersome, expensive equipment that is only [...] Read more.

Detection of nerve agents (NAs) gas in the environment through portable devices to protect people in case of emergencies still remains a challenge for scientists involved in this research field. Current detection strategies require the use of cumbersome, expensive equipment that is only accessible to specialized personnel. By contrast, emerging optical detection is one of the most promising strategies for the development of reliable, easy readout devices. However, the selectivity of the existing optical sensors needs to be improved. To overcome the lack of selectivity, the innovative strategy of the optical arrays is under evaluation due to the specific response, the ease of preparation, the portability of the equipment, and the possibility to use affordable detectors, such as smartphones, that are easily accessible to non-specialized operators. In this work, the first optical-based sensor array for the selective detection of gaseous dimethylmethylphosphonate (DMMP), a NAs simulant, is reported, employing a simple smartphone as a detector and obtaining remarkably efficient and selective detection. Full article

(This article belongs to the Special Issue Optical Chemical Sensors and Spectroscopy for Chemical Trace Element Detection)

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12 pages, 2159 KiB

Open AccessArticle

Acrylamide–Fat Correlation in Californian-Style Black Olives Using Near-Infrared Spectroscopy

by Antonio Fernández, Ismael Montero-Fernández, Olga Monago-Maraña, Elísabet Martín-Tornero and Daniel Martín-Vertedor

Chemosensors 2023, 11(9), 491; https://doi.org/10.3390/chemosensors11090491 - 06 Sep 2023

Cited by 2 | Viewed by 1052

Abstract

Californian-style is one of the most important black table olive elaborations. During its processing, table olives produce acrylamide, a potential carcinogen compound generated during sterilization. In the present study, total fat and acrylamide content in Californian-style table olives were determined and a regression [...] Read more.

Californian-style is one of the most important black table olive elaborations. During its processing, table olives produce acrylamide, a potential carcinogen compound generated during sterilization. In the present study, total fat and acrylamide content in Californian-style table olives were determined and a regression between them was performed (acrylamide concentration range: below limit of detection—2500 ng g⁻¹ and 8–22% for total fat). Nowadays, there are fast and efficient new techniques, such as Near-Infrared Spectroscopy (NIRS) to measure fat content parameters. In that sense, NIRS was used to perform a fat content quantification model in olives in order to indirectly determine acrylamide content. Calibration models for fat quantification were obtained in defatted olive pastes from a unique variety and for olive pastes from different varieties. In the first case, best results were obtained since only one variety was used (R² = 0.9694; RMSECV = 1.31%; and REP = 8.4%). However, in the second case, results were still acceptable R² = 0.678, RMSECV = 2.3%, REP = 17.7% and RMSEV = 2.17%. Regression coefficients showed the most influence variables corresponded with fat. The determination coefficient for the fat and acrylamide correlation was high (r = 0.877), being an efficient approach to find out the contribution of fat degradation to acrylamide synthesis in table olives. Full article

(This article belongs to the Special Issue Optical Chemical Sensors and Spectroscopy for Chemical Trace Element Detection)

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11 pages, 1967 KiB

Open AccessArticle

Detection of Water Vapor by Chemiluminescence

by Toshihiro Shimada, Honami Nishimoto, Hikaru Hayakawa, Hisashi Ichikawa and Yoshifumi Nakacho

Chemosensors 2023, 11(5), 284; https://doi.org/10.3390/chemosensors11050284 - 09 May 2023

Viewed by 1517

Abstract

We examined the possibility of detecting water vapor by chemiluminescence using the reaction of popular “chemical light” (bis(2,4,5-trichlorophenyl-6-carbopentoxyphenyl)oxalate with H₂O₂). H₂O₂ is released from sodium percarbonate exposed to water molecules as in the oxygen bleach. The [...] Read more.

We examined the possibility of detecting water vapor by chemiluminescence using the reaction of popular “chemical light” (bis(2,4,5-trichlorophenyl-6-carbopentoxyphenyl)oxalate with H₂O₂). H₂O₂ is released from sodium percarbonate exposed to water molecules as in the oxygen bleach. The release of H₂O₂ by water vapor was confirmed by mass spectrometry in a vacuum. The chemiluminescence from the mixed reagents was observed when exposed to water vapor. This method opens the way to locally detect the faulty points of water barrier films and observe the real-time failure of the barrier films during bending tests of flexible packing materials. A molecular dynamics simulation was performed to study the diffusion of H₂O₂ molecules in polymers. Full article

(This article belongs to the Special Issue Optical Chemical Sensors and Spectroscopy for Chemical Trace Element Detection)

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20 pages, 1634 KiB

Open AccessArticle

Development of ANN Models for Prediction of Physical and Chemical Characteristics of Oil-in-Aqueous Plant Extract Emulsions Using Near-Infrared Spectroscopy

by Sara Sirovec, Maja Benković, Davor Valinger, Tea Sokač Cvetnić, Jasenka Gajdoš Kljusurić, Ana Jurinjak Tušek and Tamara Jurina

Chemosensors 2023, 11(5), 278; https://doi.org/10.3390/chemosensors11050278 - 05 May 2023

Cited by 1 | Viewed by 1121

Abstract

The potential of applying Artificial Neural Network (ANN) models based on near-infrared (NIR) spectra for the characterization of physical and chemical features of oil-in-aqueous oregano/rosemary extract emulsions was explored in this work. Emulsions were prepared using a batch emulsification process, with pea protein [...] Read more.

The potential of applying Artificial Neural Network (ANN) models based on near-infrared (NIR) spectra for the characterization of physical and chemical features of oil-in-aqueous oregano/rosemary extract emulsions was explored in this work. Emulsions were prepared using a batch emulsification process, with pea protein as the emulsifier. NIR spectral data were connected to the results of the analysis of physical and chemical properties of the emulsions (zeta potential, Feret droplet diameter, total polyphenolic content, and antioxidant capacity) with the final aim of quantitative prediction of the physical and chemical features. For that purpose, robust non-linear multivariate analysis (Artificial Neural Network modeling) was applied. The spectra themselves were preprocessed using several approaches (raw spectra, Savitzky–Golay smoothing, standard normal variate, and multiplicative scatter corrections) after which the impact of NIR spectral preprocessing on the ANN model’s efficiency was evaluated. The results show that NIR spectroscopy integrated with ANN computation can be employed to quantitatively predict the physical and chemical properties of oil-in-plant extract emulsions (R² > 0.9). Full article

(This article belongs to the Special Issue Optical Chemical Sensors and Spectroscopy for Chemical Trace Element Detection)

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16 pages, 5897 KiB

Open AccessArticle

Ziziphus spina-christi Leaf-Derived Carbon Dots as a Fluorescence Nanosensor to Evaluate Rifaximin Antibacterial via Inner Filter Effect: Greenness and Whiteness Studies

by Mohamed A. El Hamd, Marzough Aziz Albalawi, Hassanien Gomaa, Bassam Shaaban Mohammad, Rady F. Abdul-Kareem, Reem H. Obaydo, Wejdan T. Alsaggaf, Safaa F. Saleh, Manal A. Alossaimi and Mohamed A. Abdel-Lateef

Chemosensors 2023, 11(5), 275; https://doi.org/10.3390/chemosensors11050275 - 03 May 2023

Cited by 12 | Viewed by 1661

Abstract

Rifaximin (RFX) is a non-absorbable antibiotic with broad-spectrum efficacy. It treats travelers’ diarrhea, irritable bowel syndrome, non-systematic bacterial diarrhea, bowel infections, overgrowth syndrome, and enteric infections. In this work, carbon dots prepared from Ziziphus spina-christi leaves’ powders are utilized as a green fluorometric [...] Read more.

Rifaximin (RFX) is a non-absorbable antibiotic with broad-spectrum efficacy. It treats travelers’ diarrhea, irritable bowel syndrome, non-systematic bacterial diarrhea, bowel infections, overgrowth syndrome, and enteric infections. In this work, carbon dots prepared from Ziziphus spina-christi leaves’ powders are utilized as a green fluorometric biosensor for the assessment of RFX. The morphological lineaments of the prepared carbon dots were recognized by using TEM and SEM techniques. The prepared carbon dots manifest a fluorescence emission peak at 432 nm after an excitation fluorescence peak at 366 nm. The absorbance band of RFX (absorbance peaks at 370 nm and 443 nm) could be thoroughly overlapped with fluorescence excitation/emission bands of the produced carbon dots. A fluorometric tool has been designed and validated for the evaluation of RFX reliant on the inner filter effect methodology, in which the produced carbon dots act as an inner filter effect fluorophore and RFX as an inner filter effect absorber. The quenching degree in the fluorescence activity of the prepared carbon dots depended on the concentration of RFX. The analytical parameters were checked and directed for successfully applied assessment of RFX concentration in different pharmaceutical formulations. The proposed tool’s greenness and eco-friendliness profile was evaluated using the most recent greenness assessment tool, which is the complementary green analytical procedure index (Complex-GAPI) and the Analytical GREEnness metric (AGREE). Additionally, using the recently released White Analytical Chemistry (WAC) tool, the whiteness characteristic—which indicated the method’s sustainability—was investigated. Full article

(This article belongs to the Special Issue Optical Chemical Sensors and Spectroscopy for Chemical Trace Element Detection)

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10 pages, 3008 KiB

Open AccessArticle

External-Cavity Quantum Cascade Laser-Based Gas Sensor for Sulfur Hexafluoride Detection

by Xingyu Pan, Yifan Zhang, Jiayu Zeng, Minghui Zhang and Jingsong Li

Chemosensors 2023, 11(1), 30; https://doi.org/10.3390/chemosensors11010030 - 30 Dec 2022

Cited by 3 | Viewed by 1509

Abstract

The external-cavity quantum cascade laser (ECQCL) is an ideal mid-infrared (MIR) spectral light source for determining large molecular-absorption spectral features with broad transition bands. For this paper, a gas sensor system was developed using a broadband tunable ECQCL and a direct absorption spectroscopy [...] Read more.

The external-cavity quantum cascade laser (ECQCL) is an ideal mid-infrared (MIR) spectral light source for determining large molecular-absorption spectral features with broad transition bands. For this paper, a gas sensor system was developed using a broadband tunable ECQCL and a direct absorption spectroscopy detection scheme with a short path absorption cell of 29.6 cm. For spectral signal detection, a cheap and miniaturized quartz crystal tuning fork- (QCTF) based light detector was used for laser signal detection. The characteristics of the QCTF detector were theoretically simulated and experimentally observed. To demonstrate this sensing technique, sulfur hexafluoride (SF₆) was selected as the analyte, which can be used as an effective indicator to identify fault-types of gas-insulated electrical equipment. Preliminary results indicated that a good agreement was obtained between experimentally observed data and reference spectra according to the NIST database and previous publications, and the gas sensor system showed a good linear response to SF₆ gas concentration. Finally, Allan–Werle deviation analysis indicated that detection limits of 1.89 ppm for SF₆ were obtained with a 1 s integration time, which can be further improved to ~0.38 ppm by averaging up to 131 s. Full article

(This article belongs to the Special Issue Optical Chemical Sensors and Spectroscopy for Chemical Trace Element Detection)

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15 pages, 13082 KiB

Open AccessArticle

Scanning Electron Microscopy and Raman Spectroscopy Characterization of Structural Changes Induced by Thermal Treatment in Innovative Bio-Based Polyamide Nanocomposites

by Ioana Andreea Brezeștean, Daniel Marconi, Alia Colniță, Alexandra Ciorîță, Septimiu Cassian Tripon, Zina Vuluga, Mihai Cosmin Corobea, Nicoleta Elena Dina and Ioan Turcu

Chemosensors 2023, 11(1), 28; https://doi.org/10.3390/chemosensors11010028 - 28 Dec 2022

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Abstract

A comprehensive Raman scattering-based characterization of a full bio-based polyamide loaded with graphene nanoplatelets or layered double hydroxides (LDH) was assessed. The potential of the Raman spectroscopy was used to reveal several particularities of the nanocomposite structures induced by thermal treatment. Thus, a [...] Read more.

A comprehensive Raman scattering-based characterization of a full bio-based polyamide loaded with graphene nanoplatelets or layered double hydroxides (LDH) was assessed. The potential of the Raman spectroscopy was used to reveal several particularities of the nanocomposite structures induced by thermal treatment. Thus, a complete morpho-structural picture was obtained in combination with scanning electron microscopy (SEM) analysis of the neat polyamide and polyamide nanocomposites exposed at different thermal conditions (room temperature, 80 °C, and 145 °C). The analysis of G, D and 2D Raman peaks and their relative intensity ratio I_D/I_G, revealed the fact that the presence of graphene in polyamide is suitable for improving the essential physical properties and is also responsible for the decrease in the defects’ occurrence in the graphene layers. The surface of nanocomposites based on full bio-based polyamide, with different 2D fillers (graphenic and non-graphenic structures), was carefully evaluated before and after the thermal treatment by employing SEM and Raman analyses. The two thermal treatments allowed different chain mobility of the polymer (first temperature being over the polymer T_g and second one close to the melting phase in the viscoelastic stage). The spectroscopic and microscopic investigation was used to determine the conformational changes in filler aggregates and polymer surface, respectively. Full article

(This article belongs to the Special Issue Optical Chemical Sensors and Spectroscopy for Chemical Trace Element Detection)

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Review

Jump to: Research

25 pages, 2071 KiB

Open AccessReview

Recent Progresses in Plasmonic Biosensors for Point-of-Care (POC) Devices: A Critical Review

by Caterina Serafinelli, Alessandro Fantoni, Elisabete C. B. A. Alegria and Manuela Vieira

Chemosensors 2023, 11(5), 303; https://doi.org/10.3390/chemosensors11050303 - 19 May 2023

Cited by 1 | Viewed by 1475

Abstract

The recent progresses in the research of plasmonic phenomena and materials paved the route toward the development of optical sensing platforms based on metal nanostructures with a great potential to be integrated into point-of-care (POC) devices for the next generation of sensing platforms, [...] Read more.

The recent progresses in the research of plasmonic phenomena and materials paved the route toward the development of optical sensing platforms based on metal nanostructures with a great potential to be integrated into point-of-care (POC) devices for the next generation of sensing platforms, thus enabling real-time, highly sensitive and accurate diagnostics. In this review, firstly, the optical properties of plasmonic metal nanoparticles will be illustrated, whereafter the engineering of POC platforms, such as microfluidics and readout systems, will be considered with another critical point which is surface functionalization. Attention will also be given to their potential in multiplexed analysis. Finally, the limitations for effective implementation in real diagnostics will be illustrated with a special emphasis on the latest trend in developing cutting-edge sensing systems. Full article

(This article belongs to the Special Issue Optical Chemical Sensors and Spectroscopy for Chemical Trace Element Detection)

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23 pages, 1782 KiB

Open AccessReview

Lighting Up the Heritage Sciences: The Past and Future of Laser-Induced Fluorescence Spectroscopy in the Field of Cultural Goods

by Luminița Ghervase and Ioana Maria Cortea

Chemosensors 2023, 11(2), 100; https://doi.org/10.3390/chemosensors11020100 - 01 Feb 2023

Cited by 5 | Viewed by 2367

Abstract

With the rapid scientific and technological changes that occur every day, a new kind of necessity, real-time, rapid, and accurate detection methods, preferably also non- or minimally invasive and non-destructive, has emerged. One such method is laser-induced fluorescence spectroscopy (LIF), applied in various [...] Read more.

With the rapid scientific and technological changes that occur every day, a new kind of necessity, real-time, rapid, and accurate detection methods, preferably also non- or minimally invasive and non-destructive, has emerged. One such method is laser-induced fluorescence spectroscopy (LIF), applied in various fields of activity in recent decades, ranging from industry and biochemistry to medicine and even heritage sciences. Fluorescence-based spectroscopic methods have all of the above-mentioned characteristics, and their functionality has been proven in many studies. Yet, they have not known great success as other molecular techniques. This paper is a short synthesis of the role of the laser-induced fluorescence spectroscopy technique in heritage sciences, the main applications in this field, along with its advantages and limitations. The article focuses on the most common types of lasers used, the merging of two or more methods into hybrid techniques, the enhancement of the analytical capabilities of LIF and post-processing methods, and also explores some future development possibilities of LIF. Full article

(This article belongs to the Special Issue Optical Chemical Sensors and Spectroscopy for Chemical Trace Element Detection)

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