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Keywords = cavity enhanced spectroscopy

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19 pages, 4325 KiB  
Article
The Impact of Nanoparticle Coatings on the Color of Teeth Restored Using Dental Adhesives Augmented with Magnetic Nanoparticles
by Carina Sonia Neagu, Andreea Codruta Novac, Cristian Zaharia, Meda-Lavinia Negrutiu, Izabell Craciunescu, Vlad Mircea Socoliuc, Catalin Nicolae Marin, Ionela-Amalia Bradu, Luminita Maria Nica, Marius Stef, Virgil-Florin Duma, Mihai Romînu and Cosmin Sinescu
Medicina 2025, 61(7), 1289; https://doi.org/10.3390/medicina61071289 - 17 Jul 2025
Viewed by 356
Abstract
Background and Objectives: Dental adhesives augmented with magnetic nanoparticles (MNPs) have been proposed to prevent microleakages. MNPs dispersed in a dental adhesive reduce the thickness of the adhesive layer applied in a magnetic field and enhance the bond strength by favoring the [...] Read more.
Background and Objectives: Dental adhesives augmented with magnetic nanoparticles (MNPs) have been proposed to prevent microleakages. MNPs dispersed in a dental adhesive reduce the thickness of the adhesive layer applied in a magnetic field and enhance the bond strength by favoring the penetration of the adhesive into dentinal tubules. However, the restoration’s color has been found to be affected by the MNPs. This study tests the hypothesis that MNP coating can alleviate the esthetic impact of magnetic dental adhesives. Materials and Methods: We synthesized Fe3O4 MNPs with silica coating (MNPs-SiO2), calcium-based coating (MNPs-Ca), and no coating. Their morphology was studied using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Their chemical composition was assessed by energy-dispersive X-ray spectroscopy (EDX), and magnetic properties were measured using a vibrating sample magnetometer. FTIR spectroscopy was used to evaluate the polymerization of the MNP-laden adhesive. We prepared cavities in molar phantoms divided in four groups (n = 15 each) restored using the same adhesive with different MNP contents: Group 0 (G0)—no MNPs, G1—MNPs-SiO2, G2—MNPs-Ca, and G3—uncoated MNPs. The restoration’s color was quantified in the CIELAB color space using a dental spectrophotometer. Results: MNPs-SiO2 were globular, whereas MNPs-Ca had a cubic morphology. The SiO2 layer was 73.1 nm ± 9.9 nm thick; the Ca(OH)2 layer was 19.97 nm ± 2.27 nm thick. The saturation magnetization was 18.6 emu/g for MNPs-SiO2, 1.0 emu/g for MNPs-Ca, and 65.7 emu/g for uncoated MNPs. MNPs had a marginal effect on the adhesive’s photopolymerization. The mean color difference between G0 and G2 was close to the 50:50% acceptability threshold, whereas the other groups were far apart from G0. The mean whiteness index of G2 did not differ significantly from that of G0; G1 deviated marginally from G0, whereas G3 differed significantly from G0. Conclusions: These results suggest that MNP coating can mitigate the influence of MNP-laden dental adhesives on the color of restorations. Full article
(This article belongs to the Collection New Concepts for Dental Treatments and Evaluations)
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16 pages, 2441 KiB  
Article
Phosphonium Salt-Functionalized β-Cyclodextrin Film for Ultrasensitive and Selective Electrochemical Impedance Spectroscopy Detection of Perchlorate in Drinking Water
by Zeineb Baatout, Achref Jebnouni, Nawfel Sakly, Safa Teka, Nuzaiha Mohamed, Sayda Osman, Raoudha Soury, Mabrouka El Oudi, Salman Hamdan Alsaqri, Nejmeddine Smida Jaballah and Mustapha Majdoub
Polymers 2025, 17(14), 1937; https://doi.org/10.3390/polym17141937 - 15 Jul 2025
Viewed by 396
Abstract
This work represents the first use of a phosphonium salt-functionalized β-Cyclodextrin polymer (β-CDP) as a highly selective sensing membrane for monitoring the safety of drinking water against perchlorate ions (ClO4) using electrochemical impedance spectroscopy (EIS). Structural confirmation via 1H [...] Read more.
This work represents the first use of a phosphonium salt-functionalized β-Cyclodextrin polymer (β-CDP) as a highly selective sensing membrane for monitoring the safety of drinking water against perchlorate ions (ClO4) using electrochemical impedance spectroscopy (EIS). Structural confirmation via 1H NMR, 13C NMR, 31P NMR, and FT-IR spectroscopies combined with AFM and contact angle measurements demonstrate how the enhanced solubility of modified cyclodextrin improves thin film quality. The innovation lies in the synergistic combination of two detection mechanisms: the “Host-Guest” inclusion in the cyclodextrin cavity and anionic exchange between the bromide ions of the phosphonium groups and perchlorate anions. Under optimized functionalization conditions, EIS reveals high sensitivity and selectivity, achieving a record-low detection limit (LOD) of ~10−12 M and a wide linear range of detection (10−11 M–10−4 M). Sensing mechanisms at the functionalized transducer interfaces are examined through numerical fitting of Cole-Cole impedance spectra via a single relaxation equivalent circuit. Real water sample analysis confirms the sensor’s practical applicability, with recoveries between 96.9% and 109.8% and RSDs of 2.4–4.8%. Finally, a comparative study with reported membrane sensors shows that β-CDP offers superior performance, wider range, higher sensitivity, lower LOD, and simpler synthesis. Full article
(This article belongs to the Special Issue Development of Polymer Materials as Functional Coatings)
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17 pages, 3289 KiB  
Article
Incorporation of Mometasone Furoate into a Cyclodextrin Metal-Organic Framework to Optimize Nasal Administration
by Jie Li, Yuhua Guo, Yan Liu, Qingfang Gao, Siwen Wang, Li Wu, Caifen Wang, Xiaohong Ren and Jiwen Zhang
Pharmaceutics 2025, 17(6), 788; https://doi.org/10.3390/pharmaceutics17060788 - 17 Jun 2025
Viewed by 506
Abstract
Background/Objectives: Mometasone furoate (MF) is a topical corticosteroid used to reduce allergic and inflammation symptoms. In this study, MF was incorporated into the hydrophobic cavities of γ-cyclodextrin metal-organic frameworks (CD-MOFs) to prepare MF@MOF powders for nasal delivery. Methods: MF@MOF particles were characterized [...] Read more.
Background/Objectives: Mometasone furoate (MF) is a topical corticosteroid used to reduce allergic and inflammation symptoms. In this study, MF was incorporated into the hydrophobic cavities of γ-cyclodextrin metal-organic frameworks (CD-MOFs) to prepare MF@MOF powders for nasal delivery. Methods: MF@MOF particles were characterized by scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetry. A transparent biomimetic model of the human nasal cavity was produced by 3D printing and used to evaluate intra-nasal depositions patterns. Results: Drug loading was optimized by incubating MF with a CD-MOF at a ratio of 4% for 1 h at 40 °C, and the cubic morphology and particle size of the nanoparticles were not altered using an incubation method. PXRD and FTIR analyses confirmed the successful loading of MF into the CD-MOF. Using a 3D biomimetic nasal cavity model, a 30° administration angle was found to result in reduced drug accumulation in the nasal vestibule and enhanced deposition in the respiratory and olfactory regions, compared with administration at 45°. Approximately 51% of the drug reached the respiratory zone in the model of the nasal cavity from male subjects, while almost 60% of the drug reached this zone in the model associated with female subjects. Compared with nasal sprays, nasal powder sprays had less deposition in the nasal vestibule and more deposits in the middle and inferior nasal concha. Conclusions: MF@MOF is suitable for intranasal administration. Delivery of MF as a nasal powder shows potential in the treatment of chronic rhinosinusitis. Full article
(This article belongs to the Section Pharmaceutical Technology, Manufacturing and Devices)
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27 pages, 3525 KiB  
Article
Enhancing the Drug Release and Physicochemical Properties of Rivaroxaban via Cyclodextrin Complexation: A Comprehensive Analytical Approach
by Cristina Solomon, Valentina Anuța, Iulian Sarbu, Emma Adriana Ozon, Adina Magdalena Musuc, Veronica Bratan, Adriana Rusu, Vasile-Adrian Surdu, Cătălin Croitoru, Abhay Chandak, Roxana Mariuca Gavriloaia, Teodora Dalila Balaci, Denisa Teodora Niță and Mirela Adriana Mitu
Pharmaceuticals 2025, 18(6), 761; https://doi.org/10.3390/ph18060761 - 22 May 2025
Viewed by 771
Abstract
Background/Objectives: Rivaroxaban, an oral anticoagulant, shows poor aqueous solubility, posing significant challenges to its bioavailability and therapeutic efficiency. The present study investigates the improvement of rivaroxaban’s solubility through the formation of different inclusion complexes with three cyclodextrin derivatives, such as β-cyclodextrin (β-CD), [...] Read more.
Background/Objectives: Rivaroxaban, an oral anticoagulant, shows poor aqueous solubility, posing significant challenges to its bioavailability and therapeutic efficiency. The present study investigates the improvement of rivaroxaban’s solubility through the formation of different inclusion complexes with three cyclodextrin derivatives, such as β-cyclodextrin (β-CD), methyl-β-cyclodextrin (Me-β-CD), and hydroxypropyl-β-cyclodextrin (HP-β-CD) prepared by lyophilization in order to stabilize the complexes and improve dissolution characteristics of rivaroxaban. Methods: The physicochemical properties of the individual compounds and the three lyophilized complexes were analysed using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Results: FTIR spectra confirmed the formation of non-covalent interactions between rivaroxaban and the cyclodextrins, suggesting successful encapsulation into cyclodextrin cavity. SEM images revealed a significant morphological transformation from the crystalline structure of pure rivaroxaban and cyclodextrins morphologies to a more porous and amorphous matrix in all lyophilized complexes. XRD patterns indicated a noticeable reduction in drug crystallinity, supporting enhanced potential of the drug solubility. TGA analysis demonstrated improved thermal stability in the inclusion complexes compared to the individual drug and cyclodextrins. Pharmacotechnical evaluation revealed that the obtained formulations (by comparison with physical mixtures formulations) possessed favorable bulk and tapped density values, suitable compressibility index, and good flow properties, making all suitable for direct compression into solid dosage forms. Conclusions: The improved cyclodextrins formulation characteristics, combined with enhanced dissolution profiles of rivaroxaban comparable to commercial Xarelto® 10 mg, highlight the potential of both cyclodextrin inclusion and lyophilization technique as synergistic strategies for enhancing the solubility and drug release of rivaroxaban. Full article
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16 pages, 1493 KiB  
Article
Laboratory Cross-Sensitivity Evaluation of Low-Cost Electrochemical Formaldehyde Sensors
by Zheyuan Pei and Kerry E. Kelly
Sensors 2025, 25(10), 3096; https://doi.org/10.3390/s25103096 - 14 May 2025
Viewed by 739
Abstract
Formaldehyde is the most abundant carbonyl globally and the biggest driver of cancer risk in the United States among hazardous air pollutants. Ambient formaldehyde concentration measurements are generally sparse due to high measurement costs and limited measurement infrastructure. Recent studies have used low-cost [...] Read more.
Formaldehyde is the most abundant carbonyl globally and the biggest driver of cancer risk in the United States among hazardous air pollutants. Ambient formaldehyde concentration measurements are generally sparse due to high measurement costs and limited measurement infrastructure. Recent studies have used low-cost air quality sensors to affordably improve spatial coverage and provide real-time measurements. Our previous research evaluated the laboratory performance of a low-cost electrochemical formaldehyde sensor (Sensirion SFA30) over formaldehyde concentrations ranging from 0 to 76 ppb. The sensors exhibited good linearity of response, a low limit of detection, and good accuracy in detecting formaldehyde. This study evaluated the cross-sensitivity of the SFA30 and the Gravity sensors (electrochemical formaldehyde sensors) over formaldehyde concentrations ranging from 0 to 326 ppb in a laboratory evaluation system, with broadband cavity-enhanced absorption spectroscopy used to obtain the reference measurements. We evaluated the sensors in a mixture of formaldehyde with five outdoor trace gases (CO, NO, NO2, O3, and isobutylene) and two indoor VOCs (methanol and isopropyl alcohol). The results suggest that the Gravity sensors may be useful for outdoor formaldehyde measurements when formaldehyde levels are well above background levels and that the SFA30 sensors may be useful screening tools for indoor environments, if properly calibrated. Full article
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23 pages, 23181 KiB  
Article
Ultrasound-Assisted Ferritin Extraction from Northern Pike Liver: An Innovative Approach for Chlorogenic Acid Encapsulation with Enhanced Thermal Stability
by Zhikun Xing, Yi Wang, Yabo Wei, Xin Guo, Xiaoyue Liang, Xiaorong Deng, Lianfu Zhang and Jian Zhang
Molecules 2025, 30(9), 2080; https://doi.org/10.3390/molecules30092080 - 7 May 2025
Cited by 1 | Viewed by 531
Abstract
Ferritin, an emerging protein resource, has garnered significant attention in scientific research due to its biocompatibility and unique cavity structure capable of encapsulating bioactive compounds. This study aimed to optimize ultrasound-assisted extraction (UAE) for enhancing ferritin yield from northern pike liver byproducts and [...] Read more.
Ferritin, an emerging protein resource, has garnered significant attention in scientific research due to its biocompatibility and unique cavity structure capable of encapsulating bioactive compounds. This study aimed to optimize ultrasound-assisted extraction (UAE) for enhancing ferritin yield from northern pike liver byproducts and evaluate its potential as a nanocarrier for chlorogenic acid (CA). Through response surface methodology (RSM), the optimal UAE parameters were established as 200 W ultrasonic power, 1:3 solid–liquid ratio, and 25 min extraction time. Under these conditions, the ferritin extraction yield reached 139.46 mg/kg, representing a 4.02-fold increase compared to conventional methods (34.65 mg/mL). Electrophoretic analysis confirmed the electrophoretic purity of the extracted liver ferritin. Comprehensive characterization using UV-vis spectroscopy, FTIR, and fluorescence spectroscopy revealed preserved structural integrity of UAE-extracted ferritin. Homology modeling provided molecular insights into the ferritin architecture. Successful encapsulation of CA was achieved with an encapsulation efficiency of 13.25%, as quantified by HPLC. Analysis by DLS and ζ potential as well as TG and DSC showed that not only the thermal stability of CA was enhanced after ferritin encapsulation, but also that the ferritin remained stable with a cage-like structure. This investigation establishes UAE as an effective strategy for valorizing fish processing byproducts through high-yield ferritin extraction while demonstrating the protein’s functional capacity as a nanocarrier for bioactive compound delivery. The findings highlight the dual advantage of sustainable resource utilization and advanced delivery system development through this biotechnological approach. Full article
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19 pages, 2546 KiB  
Article
Physical Modification of Whey Protein by Interacting with Methyl Hesperidin: Impacts on Antioxidant Activity and Underlying Mechanism
by Songbo Ma, Shuang Yang, Suqi Yang, Lili Chen, Meilan Yuan, Yong Jiang, Li Zhao and Chunqing Bai
Biology 2025, 14(5), 492; https://doi.org/10.3390/biology14050492 - 1 May 2025
Viewed by 433
Abstract
In this work, the possibility of enhancing the antioxidant capacity of whey protein (WP) through non-covalent interaction with methyl hesperidin (MH, a hesperidin derivative) was assessed. The underlying mechanism was analyzed in terms of multi-spectroscopy methods, thermodynamic analysis, and molecular docking simulation. The [...] Read more.
In this work, the possibility of enhancing the antioxidant capacity of whey protein (WP) through non-covalent interaction with methyl hesperidin (MH, a hesperidin derivative) was assessed. The underlying mechanism was analyzed in terms of multi-spectroscopy methods, thermodynamic analysis, and molecular docking simulation. The data indicated that MH could spontaneously bind to WP and form a non-fluorescent complex when physically mixed together. The presence of MH statically quenched the intrinsic fluorescence of WP, changed the microenvironment of amino acid residue, and altered the secondary and tertiary structure of WP, which in turn enhanced the antioxidant capacity of WP. The underlying mechanism may be assigned to hydrophobic interactions, which promoted MH inserting itself into the hydrophobic cavity in WP. The methoxy group on the B ring of MH may form hydrogen bonds with amino acids, which enhances the freedom of the phenyl hydroxyl group, resulting in higher antioxidant capacity than other hesperidin structural analogs. This research would enrich the theoretical basis about the interaction between protein and hesperidin-based derivatives, and it may supply valuable information for its application in the food and medicine fields. Full article
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14 pages, 2986 KiB  
Article
Magnetic and MRI Contrast Properties of HumAfFt-SPIONs: Investigating Superparamagnetic Behavior and Enhanced T2-Weighted Imaging Performance
by Luisa Affatigato, Mariano Licciardi, Maria Cristina D’Oca, Luca Cicero, Alessandra Bonamore, Alessio Incocciati, Alberto Macone, Christian Dirk Buch, Stergios Piligkos, Alberto Boffi and Valeria Militello
Int. J. Mol. Sci. 2025, 26(8), 3505; https://doi.org/10.3390/ijms26083505 - 9 Apr 2025
Viewed by 578
Abstract
The present study introduces a novel theranostic nanoparticle platform that integrates superparamagnetic iron oxide nanoparticles (SPIONs) with a ferritin-based protein nanocage derived from the archaeobacterium Archaeoglobus fulgidus. By exploiting the unique salt-triggered dissociation and reassociation mechanism of the nanocage, SPIONs were successfully [...] Read more.
The present study introduces a novel theranostic nanoparticle platform that integrates superparamagnetic iron oxide nanoparticles (SPIONs) with a ferritin-based protein nanocage derived from the archaeobacterium Archaeoglobus fulgidus. By exploiting the unique salt-triggered dissociation and reassociation mechanism of the nanocage, SPIONs were successfully encapsulated within the protein’s central cavity. The construct thus obtained was characterized by transmission electron microscopy and circular dichroism spectroscopy. The ferritin-coated SPIONs exhibited remarkable superparamagnetic behavior and robust magnetic properties. Characterization using electron paramagnetic resonance and thermal magnetization analysis confirmed the stability of the nanoparticles and their suitability for magnetic hyperthermia applications. Furthermore, T2-weighted magnetic resonance imaging (MRI) demonstrated enhanced contrast, with ferritin-coated SPIONs generating distinct dark-spot imaging, highlighting their efficacy as a contrast agent for advanced biomedical applications. Full article
(This article belongs to the Section Molecular Nanoscience)
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20 pages, 2708 KiB  
Article
Sustainable Pest Management with Hollow Mesoporous Silica Nanoparticles Loaded with β-Cypermethrin
by Min Li, Linmiao Xue, Teng Gao, Zhuo Zhang, Dan Zhao, Xing Li and Zhanhai Kang
Agronomy 2025, 15(3), 737; https://doi.org/10.3390/agronomy15030737 - 19 Mar 2025
Cited by 1 | Viewed by 724
Abstract
β-cypermethrin (BCP) is a broad-spectrum insecticide known for its rapid efficacy. However, it is highly toxic to non-target organisms such as bees and fish, and its effectiveness is limited by a short duration of action. Improving the release profile of BCP is essential [...] Read more.
β-cypermethrin (BCP) is a broad-spectrum insecticide known for its rapid efficacy. However, it is highly toxic to non-target organisms such as bees and fish, and its effectiveness is limited by a short duration of action. Improving the release profile of BCP is essential for reducing its environmental toxicity while preserving its effectiveness. In this study, hollow mesoporous silica nanoparticles (HMSNs) were synthesized using a self-templating method, and BCP-loaded HMSNs were prepared through physical adsorption. The structural and physicochemical properties of the nanoparticles were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption–desorption analysis, Fourier transform infrared (FT-IR) spectroscopy, dynamic light scattering (DLS), and thermogravimetric analysis (TGA). The BCP release profile was assessed using the dialysis bag method. The results showed that the synthesized nanoparticles exhibited uniform morphology, thin shells, and large internal cavities. The HMSNs had a pore size of 3.09 nm, a specific surface area of 1318 m2·g−1, a pore volume of 1.52 cm3·g−1, and an average particle size of 183 nm. TEM, FT-IR, and TGA analyses confirmed the successful incorporation of BCP into the HMSNs, achieving a drug loading efficiency of 32.53%. The BCP-loaded nanoparticles exhibited sustained-release properties, with an initial burst followed by gradual release, extending efficacy for 30 days. Safety evaluations revealed minimal toxicity to maize seedlings, confirming the biocompatibility of the nanoparticles. These findings indicate that BCP-loaded HMSNs can enhance the efficacy of BCP while reducing its environmental toxicity, providing a biocompatible and environmentally friendly solution for pest control. Full article
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22 pages, 6941 KiB  
Article
Preparation of Eugenol–Thymol–Cuminal Composite Essential Oil Microcapsules with AITC & β-Cyclodextrin Inclusion Complex and Its Effect on Quality of Chilled Pork
by Wenxiao Li, Fan Yang, Li Chen, Ke Ding and Xiangning Chen
Foods 2025, 14(6), 1029; https://doi.org/10.3390/foods14061029 - 18 Mar 2025
Viewed by 708
Abstract
The preservation of chilled fresh pork is an issue that has widely drawn significant attention. A novel microcapsule was developed in this study, specifically a composite plant essential oil microcapsule (CEO mps) prepared using gum arabic (GA) and an inclusion compound of allyl [...] Read more.
The preservation of chilled fresh pork is an issue that has widely drawn significant attention. A novel microcapsule was developed in this study, specifically a composite plant essential oil microcapsule (CEO mps) prepared using gum arabic (GA) and an inclusion compound of allyl isothiocyanate (AITC) with β-cyclodextrin (β-CD), in which AITC is encapsulated within the cavity of β-CD molecules. In this formulation, AITC functions as an antibacterial agent, while the essential oils provide antioxidant properties that further enhance bacterial inhibition. The encapsulation ratio of AITC to β-CD was optimized at 1:1, with nuclear magnetic resonance (NMR) hydrogen spectroscopy confirming that AITC was incorporated into β-CD through its wider cavity. The morphology and structure of CEO mps were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and laser particle size analysis, and these were compared to those of AITC mps—microcapsules prepared with GA and β-CD as wall materials and AITC as the core material. The results indicated that CEO mps exhibited superior appearance and physical stability in comparison to AITC mps. The release rate of CEO mps was evaluated using gas chromatography–mass spectrometry (GC/MS), revealing sustained release characteristics. On day 12, cumulative releases for AITC, eugenol, cuminal, and thymol were 61.82%, 57.96%, 44.34%, and 38.65%. Finally, the efficacy of CEO mps in preserving chilled pork was assessed by measuring pH levels, total volatile base nitrogen (TVB-N), color parameters (L*, a*, b*), thiobarbituric acid-reactive substances (TBARSs), water loss, and total microbial counts. The results demonstrated that CEO mps significantly inhibited microbial growth in chilled pork, reduced TBARS and TVB-N values, and helped preserve meat color integrity, thereby effectively extending shelf life by approximately six days. Overall, the experimental findings confirmed that the developed CEO mps possess both antibacterial and antioxidant properties, thereby improving both the shelf life and organoleptic quality of chilled pork. Full article
(This article belongs to the Section Food Packaging and Preservation)
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14 pages, 4532 KiB  
Article
Research on Enhancement of LIBS Signal Stability Through the Selection of Spectral Lines Based on Plasma Characteristic Parameters
by Yunfeng Xia, Honglin Jian, Qishuai Liang and Xilin Wang
Chemosensors 2025, 13(2), 42; https://doi.org/10.3390/chemosensors13020042 - 1 Feb 2025
Cited by 1 | Viewed by 1248
Abstract
Laser-induced breakdown spectroscopy (LIBS) is widely used for online quantitative analysis in industries due to its rapid analysis and minimal damage. However, challenges like signal instability, matrix effects, and self-absorption hinder the measurement accuracy. Recent approaches, including the internal standard method and crater [...] Read more.
Laser-induced breakdown spectroscopy (LIBS) is widely used for online quantitative analysis in industries due to its rapid analysis and minimal damage. However, challenges like signal instability, matrix effects, and self-absorption hinder the measurement accuracy. Recent approaches, including the internal standard method and crater limitation method, aim to improve the stability but suffer from high computational demands or complexity. This study proposes a method to enhance LIBS stability by utilizing craters formed from laser ablation without external cavity assistance. It first improves the plasma temperature calculation reliability using multiple elemental spectral lines, after which electron density calculations are performed. By fitting plasma parameter curves based on laser pulse counts and using a laser confocal microscope for crater analysis, stable plasma conditions were found within crater areas of 0.400 mm2 to 0.443 mm2 and depths of 0.357 mm to 0.412 mm. Testing with elemental spectral lines of Ti II, K II, Ca I, and Fe I showed a significant reduction in the relative standard deviation (RSD) of the LIBS spectral line intensity, demonstrating an improved signal stability within specified crater dimensions. Full article
(This article belongs to the Special Issue Application of Laser-Induced Breakdown Spectroscopy, 2nd Edition)
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14 pages, 8728 KiB  
Article
OA−ICOS−Based Oxygen and Carbon Dioxide Sensors for Field Applications in Gas Reflux Chicken Coops
by Weijia Li, Guanyu Lin, Jianing Wang, Jifeng Li, Yulai Sun, Depu Yao, Xiaogang Yan and Zhibin Ban
Sensors 2025, 25(3), 886; https://doi.org/10.3390/s25030886 - 31 Jan 2025
Viewed by 906
Abstract
To facilitate the effective assessment of respiratory entropy during poultry breeding, a novel oxygen (O2) and carbon dioxide (CO2) sensor was developed based on the off−axis integrated cavity output spectroscopy technique, featuring effective absorption optical paths of 15.5 m [...] Read more.
To facilitate the effective assessment of respiratory entropy during poultry breeding, a novel oxygen (O2) and carbon dioxide (CO2) sensor was developed based on the off−axis integrated cavity output spectroscopy technique, featuring effective absorption optical paths of 15.5 m and 8.5 m, respectively. The sensor employs integrated environmental control technology, substantially enhancing detection precision. To improve the instrument’s response speed, the miniaturization of the cavity and structural optimization were implemented, achieving a rapid response time of merely 6.22 s, addressing the stringent requirements for quick responsiveness in poultry respiration thermometry research. A signal processing model tailored for on−site applications was designed, boosting the system’s signal−to−noise ratio by 4.7 times under complex environmental noise conditions. Utilizing Allan variance analysis, the sensor’s detection limits for O2 and CO2 were ascertained to be 2.9 ppm and 7.4 ppb, respectively. A 24−h field application test conducted in Gongzhuling demonstrated that the sensor’s results align with the respiratory characteristics of poultry under normal physiological conditions, validating its extensive potential for application in respiratory analysis, environmental monitoring, and industrial sectors. Full article
(This article belongs to the Section Environmental Sensing)
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16 pages, 2872 KiB  
Article
Encapsulation of Vecuronium and Rocuronium by Sugammadex Investigated by Surface-Enhanced Raman Spectroscopy
by Adriana Kenđel, Ivo Piantanida and Snežana Miljanić
Molecules 2025, 30(2), 231; https://doi.org/10.3390/molecules30020231 - 9 Jan 2025
Cited by 1 | Viewed by 1222
Abstract
Aiming toward a novel, noninvasive technique, with a real-time potential application in the monitoring of the complexation of steroidal neuromuscular blocker drugs Vecuronium (Vec) and Rocuronium (Roc) with sugammadex (SDX, medication for the reversal of neuromuscular blockade [...] Read more.
Aiming toward a novel, noninvasive technique, with a real-time potential application in the monitoring of the complexation of steroidal neuromuscular blocker drugs Vecuronium (Vec) and Rocuronium (Roc) with sugammadex (SDX, medication for the reversal of neuromuscular blockade induced by Vec or Roc in general anesthesia), we developed proof-of-principle methodology based on surface-enhanced Raman spectroscopy (SERS). Silver nanoparticles prepared by the reduction of silver ions with hydroxylamine hydrochloride were used as SERS-active substrates, additionally aggregated with calcium nitrate as needed. The Vec and Roc SERS spectra were obtained within the biorelevant 5 × 10−7–1 × 10−4 M range, as well as the SERS of SDX, though the latter was observed only in the presence of the aggregating agent. SDX/drug complexes at a 1/1 molar ratio revealed significant spectral changes in the vibrational bands of the SDX glucose rings and the drug steroid rings, implying that the insertion of Vec and Roc molecules into the SDX cavity was not only driven by attractive electrostatic interactions between the positively charged cyclic unit of the drug and the negative carboxylate groups of cyclodextrin but also supported by hydrophobic interactions between the host cyclodextrin and the guest drug molecule. The observed changes in SERS signals are applicable in biorelevant conditions and support further studies of SDX/drug complexes in vivo. Full article
(This article belongs to the Section Analytical Chemistry)
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17 pages, 8085 KiB  
Article
Development of HfO₂-Based Solar-Blind SAW UV-C Sensor for Corona Discharge Detection Application
by Hyunho Lee, Faisal Nawaz, Eeunsun Shim, Jinjae Lee, Cheol Choi and Keekeun Lee
Appl. Sci. 2025, 15(1), 464; https://doi.org/10.3390/app15010464 - 6 Jan 2025
Viewed by 1160
Abstract
This study presents a novel surface acoustic wave (SAW)-based solar-blind ultraviolet-C (UV-C) corona sensor, marking the first reported use of HfO₂ as a sensing material for UV-C corona sensing. A 222 MHz two-port SAW delay line structure was selected as a sensor platform, [...] Read more.
This study presents a novel surface acoustic wave (SAW)-based solar-blind ultraviolet-C (UV-C) corona sensor, marking the first reported use of HfO₂ as a sensing material for UV-C corona sensing. A 222 MHz two-port SAW delay line structure was selected as a sensor platform, and its optimal parameters were determined through Coupling of Mode (COM) modeling analysis. COMSOL simulations were conducted to investigate the effect of UV-C exposure on the HfO2 thin film, highlighting its contribution to conductivity changes. A 30 nm-thick HfO2 thin film was deposited using atomic layer deposition (ALD) within the cavity of a two-port SAW delay line, providing sufficient volume and density of absorption sites for UV-C exposure. Comprehensive material characterization of the HfO2 thin film was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The effect of annealing temperature was analyzed in detail, with results confirming that 500 °C is the optimal temperature for achieving the best performance in a SAW-based UV-C corona sensor. The sensor characteristics were measured using custom-made interface electronics, allowing frequency shifts to be visually observed on a PC monitor with compensation for environmental factors such as humidity and temperature. The developed sensor demonstrated response and recovery times of 2.8 s and 4 s, respectively, with a measured sensitivity of 563 ppm/(mW·cm−2). Furthermore, the effect of HfO₂ film thickness on the sensor’s response to UV-C exposure was examined in detail, showing that increased thickness leads to a higher frequency shift, thereby enhancing sensitivity. The feasibility of the sensor for real-world applications was validated through successful testing under simulated corona discharge detection. Full article
(This article belongs to the Special Issue Surface Acoustic Wave Sensors: Current Designs and Applications)
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10 pages, 4395 KiB  
Article
Enhancing Terahertz Absorption Spectrum Based on a Tunable Defect Cavity of One-Dimensional Photonic Crystal in the Combined Coaxial Waveguide
by Lu Nie, Xiangjun Li, Dongzhe Chen, Zihao Wang and Dexian Yan
Photonics 2025, 12(1), 14; https://doi.org/10.3390/photonics12010014 - 27 Dec 2024
Viewed by 755
Abstract
Terahertz (THz) molecular fingerprint spectroscopy provides a powerful label-free tool for detecting trace-amount analytes. Introducing extra microstructures such as metasurfaces to confine the field energy is essential to improve the sensitivity. However, the area of analyte film on conventional enhancing metasurfaces must be [...] Read more.
Terahertz (THz) molecular fingerprint spectroscopy provides a powerful label-free tool for detecting trace-amount analytes. Introducing extra microstructures such as metasurfaces to confine the field energy is essential to improve the sensitivity. However, the area of analyte film on conventional enhancing metasurfaces must be larger than the beam spot in a free-space measuring setup. Here, we propose a tunable defect cavity of one-dimensional photonic crystal in the combined coaxial waveguide (CCW) and enhance the broadband THz fingerprint of trace analytes on a much smaller area. The peaks of high Q resonances can form a wide absorption spectrum by changing the length of the rubber part of the coaxial waveguide. For the 0.2 µm α-lactose film sample in the frequency range of 0.48–0.58 THz, the absorption enhancement factor of 89.2 times based on the thickness can be achieved and the sample area is about 1/1700 of that in the free-space measurement with the 5 mm beam waist. We first introduce the coaxial waveguide in the terahertz absorption spectra enhancement. With our proposed structure the analyte volume is effectively reduced which is significant in the real application scenario. Full article
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