Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy最新文献

The development of B-lymphoblastic leukemia is tightly associated with aberrant expression of Pax-5a. This work presented a novel dual signal amplification strategy-based Pax-5a detection method by combining the rolling circle amplification reaction (RCA) and the Entropy-driven toehold-mediated strand displacement (ETSD). Particularly noteworthy is the employed ETSD, which effectively improves the rate and stability of the reaction due to its unique entropy-driven principle. The uniqueness of this method is the combination of two amplification techniques, each utilizing its own strengths to achieve our intended purpose. This sensing method has been effectively used to determine the Pax-5a gene which with a reliable linear correlation for detection within a range and achieving a detection limit of 3.34 pM, calculated using the formula (3σ/S). Furthermore, even in 1 % of human serum samples, the biosensor can identify the target gene with exceptional sensitivity. The recovery rates fall within the range of 96.68-101.76 %, with a relative standard deviation (RSD) of 5.47 %. The method has a strong specificity based on sequence-specific hybridization of nucleic acids, thereby effectively preventing potential false-positive results. This fluorescent biosensor has a high detection capability for Pax-5a, and offers stable results. It provides a new way for early clinical diagnosis of acute lymphoblastic leukemia.

Sunlight-induced degradable squarazine based electron deficient receptor 3,4-bis((E)-2-((perfluorophenyl)methylene)hydrazinyl)cyclobut-3-ene-1,2-dione, L has been reported here. Naked-eye colorimetric analysis, UV-Vis, IR and ¹H, 19F, ³¹P-NMR spectrometric results show that this receptor L high affinity with cyanide anion. The strength of the receptor L towards colorimetrically responded anions are calculated by UV-Vis spectrometric titrations and it is found to be 9.9597 × 10³ for cyanide. Interestingly, upon exposure of those anionic complexes under sunlight, the colors of those respective anionic complexes are disappeared. From this result, it is clear that these anionic complexes are capable to discharge the bound anion via CN free rotation. As evidenced from spectroscopic and colorimetric results, it is also clear that this anionic complex is not only release the bound anion, but also undergone self-degradation upon sunlight exposure. To the best of our knowledge, this is the first example for cyanide sensing of anion accomplished with self-degradation of anion complex upon exposure on sunlight.

Aquatic systems with low zinc levels can experience a significant decrease in carbon dioxide uptake and limited growth of phytoplankton species. In this study, we describe the use of a new fluorescent sensor based on NH₂-MIL-53(Al), and modified with glutaraldehyde and sulfadoxine, for selectively detecting zinc ions in water and blood serum samples. Characterization of the synthesized material was performed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) surface area analysis, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM), confirming successful functionalization and preservation of the MOF structure. The sensor's performance for Zn²⁺ detection was evaluated by spectrofluorometry, demonstrating a significant fluorescence enhancement upon Zn²⁺ binding due to the interaction between Zn²⁺ ions and the sulfonamide groups. With a detection limit as low as 3.14 × 10^-2 ppm, the sensor demonstrates high selectivity for Zn²⁺ over other common metal ions. The sensor's response is rapid, stable, and reproducible, making it suitable for practical applications. Real sample analysis was conducted in tap water and blood serum samples, with the results compared to those obtained using ICP-OES and a colorimetric test with 5-bromo-PAPS. The comparison confirmed the high accuracy and reliability of the fluorescent sensor in detecting Zn²⁺ ions in complex matrices. NH₂-MIL-53(Al) modified with glutaraldehyde and sulfadoxine shows potential as a selective fluorescent sensor for Zn²⁺ detection, making it a valuable tool for monitoring the environment and biology.

In this study, simultaneous determination of levodopa (LEV) and carbidopa (CBD) in binary mixtures, pharmaceutical formulation, and biological sample was conducted using the application of simple, fast, sensitive, and accurate UV-spectrophotometry in combination with chemometrics methods. The first method is net analyte signal (NAS) based on the multivariate calibration methods. The limit of detection (LOD) and limit of quantification (LOQ) were 0.9758, 0.7633 µg/mL and 2.956, 2.313 µg/mL over the linear range of 5-40 and 0.5-20 µg/mL for LEV and CBD, respectively. In the NAS approach, the mean recovery values of mixtures were 100.12 % for LEV and 99.65 % for CBD, where root mean square error (RMSE) values were 0.0106 and 0.0141 for LEV and CBD, respectively. The second method is absorbance subtraction (AS) based on the absorption factor technique for analyzing the isosbestic point. This model was constructed at an isosbestic point of 261 nm in the range of 5-40 and 0.5-20 µg/mL with coefficient determination (R²) of 0.9985 and 0.9996 for LEV and CBD, respectively. AS method could estimate LEV and CBD with LOD values of 1.924 and 0.5657 μg/mL and LOQ values of 5.833 and 1.714 μg/mL, respectively. The recovery percentage was between 91.50 % to 104.60 % with RMSE of 0.1455 for LEV and 92.00 % to 106.66 % with RMSE of 0.2508 for CBD. The introduced approaches have the benefit of concurrent analysis of the mentioned components without any pretreatment. Statistical comparison of the results of real sample analysis with high-performance liquid chromatography (HPLC) did not show a significant difference. These methods can replace HPLC in quality control laboratories when fast, precise, and low-cost analysis is needed.

This study designed and developed an innovative online detection device based on Continuous Solid-Phase Extraction Spectroscopy (CSPES) for rapid quantitative analysis of environmental water pollutants. The device is highly automated, eliminating environmental interference. Leveraging CSPES technology and adsorption kinetics theory, an online quantitative analysis model between the spectrum and component concentrations was established, along with a concentration calculation method based on the least squares method. The quantitative analysis method was validated using single-component and binary-component sample systems containing Fluoranthene, Benzo[k]Fluoranthene, and Rhodamine 6G. The model exhibited excellent predictive performance, with overall prediction concentration relative errors (RE) ranging from 0.45 % to 8.75 % and relative standard deviations (RSD) of less than 3 %. In real sample applications, recovery rates ranged from 86.8 % to 124.4 %, with RSDs between 0.33 % and 2.22 %. This method provides a robust tool for water quality monitoring and environmental analysis, holding significant potential for application across various fields.

Selective imaging of superoxide anion is important for understanding its role in cell membrane biology, but is often a challenging task because of the lack of an effective fluorescence probe. In this study, a new near-infrared fluorescent probe (SHX-O) that can target cell membrane was developed for imaging superoxide anion. SHX-O was designed by simultaneously incorporating a sulfonated bis-indole and a diphenylphosphinyl recognition group into the hemicyanine moiety. The probe itself showed a rather weak fluorescence due to the hemicyanine's hydroxyl substitution; however, its reaction with superoxide anion caused a large enhancement of near-infrared fluorescence at 790 nm. Moreover, SHX-O exhibited not only high selectivity for superoxide anion over other reactive oxygen species, but also specific cell membrane localization, which may be attributed to the probe's amphiphilic structure. Using the probe, fluorescence imaging of cell membrane superoxide anion produced in the presence of xanthine oxidase and xanthine has been achieved in living cells. We believe that SHX-O may serve as a potential tool for imaging and investigating superoxide anion of cell membrane.

Antioxidant activity, as a topic of current interest, is discussed together with the excited state intramolecular proton transfer (ESIPT) process for three flavonoid derivatives, based on density functional theory (DFT)and time-dependent DFT (TD-DFT) methods, as well as DPPH free radical scavenging assay. The potential energy curves and transition states demonstrate that the three molecules can undergo only single proton transfer in the excited state, and all of them are ultrafast ESIPT processes. The absorption spectra of all the molecules show effective protection against UV radiation with low fluorescence intensity, especially Baicalein (Bai), which demonstrates their great potential for sunscreen applications. The density of states, HOMO energy values, global and local indices reveal that the antioxidant activity of the molecules after ESIPT process is enhanced, with Bai having the highest antioxidant activity, which is significantly attributed to the number and position of phenolic hydroxyl groups. Moreover, by comparing the DPPH free radical scavenging activity under the dark and UV radiation conditions, the radical scavenging activity (RSA) value in the UV radiation is remarkably higher than that in the dark condition, in which Bai achieves RSA value of 93.4%. Overall, the antioxidant activity of all three ESIPT-based flavonoid derivatives, especially Bai, is significantly elevated in the keto* form, which reinforces the significant relationship between antioxidant activity and ESIPT process, and provides new application prospects for molecules with ESIPT properties.

Nitrite is a commonly used food preservative and a water contaminant that has garnered significant attention due to its harmful effects on human health. Developing a simple and sensitive method for determining nitrite levels is crucial for safeguarding public health. In this paper, we present a novel ratiometric fluorescent nanosensor (CDs@UiO-66-NH₂), created by combining orange-red-emitting CDs with blue-emitting UiO-66-NH₂. This ratiometric probe detects nitrite ions (NO₂^-) based on the diazotization reaction between the amino group in UiO-66-NH₂ and the target NO₂^-, where the blue emission of UiO-66-NH₂ is quenched but the orange-red emission of CDs remains stable. The probe demonstrated a detection range of 0.5-20 μM with a limit of detection (LOD) of 0.157 μM for NO₂^-. Due to the probe's distinct color changes in response to NO₂^-, RGB values can be easily read using a smartphone, enabling ultrasensitive visual detection of NO₂^- with an LOD of 0.76 μM. This sensor was successfully applied to detect NO₂^- in environmental water samples. Finally, a smartphone-based RGB reading method using CDs@UiO-66-NH₂ for visual quantitative detection of NO₂^- was proposed, broadening the application of CDs@UiO-66-NH₂ in environmental protection.

As the degree of anisotropy in nanoparticle morphology increases, the resulting electromagnetic enhancement can be significantly intensified. Herein, we have attempted to develop anisotropic gold-silver (a-AuAg) nanoparticles deposited on a titanium sheet (a-AuAg@Ti) as a highly efficient Surface-enhanced Raman Spectroscopy (SERS) sensor for rapid detection of health-hazardous milk adulterants like melamine. Hierarchical a-AuAg nanoparticles have been synthesized via a facile seed and growth-mediated method, followed by immobilization on a titanium sheet using a drop-casting technique. The structural, morphological, chemical, and optical properties of a-AuAg@Ti sensors have been systematically investigated and correlated with their respective SERS performance. Morphological analysis revealed the occurrence of triangular, hexagonal, and pentagonal-shaped nanoparticles with an average particle size of ∼ 23 to 26 nm. Preliminary SERS analysis using Rhodamine 6G (R6G) probe molecule revealed significantly higher SERS activity for a-AuAg nanoparticles compared to their spherical counterparts. This could be attributed to the lightning rod effect associated with the synthesized anisotropic nanostructures. An enhancement factor of 1.7 x 10⁸ has been estimated for a-AuAg@Ti sensor with excellent signal reproducibility. Further, the efficacy of melamine detection has been investigated by spiking it into water and milk samples. The estimated lower detection limit (LDL) near picomolar and nanomolar concentrations have been obtained for melamine-spiked samples in water and milk, respectively. High-performance liquid chromatography analysis for melamine revealed an LDL of only 0.1 µM, indicating the higher sensitivity of a-AuAg@Ti SERS sensor. Moreover, we have also analyzed commercial milk products to verify the melamine contents, but none of them showed melamine-specific fingerprint bands. Our findings highlight the superior sensitivity of a-AuAg@Ti substrates for real-time melamine detection, making them excellent optical sensing tools for food safety analysis.

Raman spectroscopy is a powerful analytical method, but when the composition of the test sample is intricate, the original spectral data may contain noise and fluorescence background interference, making it more difficult to extract Raman spectral information from the original spectra. Especially the fluorescence background signal, which is typically several orders of magnitude stronger than the Raman signal, can even overwhelm or obscure the Raman signals, thereby impeding the qualitative or quantitative analysis of the Raman spectra. One effective method for removing the fluorescence background is shift excitation Raman differential spectroscopy (SERDS), which typically involves measuring two raw Raman spectra using slightly different excitation wavelengths, combined with reconstruction algorithms, to obtain Raman spectra free from fluorescence interference. For this purpose, a reconstruction method based on Tikhonov regularized least squares (TRLS) was developed in this study, which mitigated the oscillations caused by the direct unconstrained least squares (DULS) reconstruction method. The method was verified and optimized using four groups of artificial datasets with different characteristics. By selecting an appropriate value for parameter α, the relative standard deviation (RSD) of the reconstructed datasets was lower than that of the artificial datasets in most cases. Additionally, we evaluated the performance of the TRLS reconstruction algorithm based on a quantitative model of real Raman spectral datasets, assessing the algorithm's performance from three perspectives: the root mean square error (RMSE), the correlation coefficient (R), and the ratio of prediction to deviation (RPD). The quantitative results indicate that using the TRLS method for reconstruction enhances both prediction accuracy and practicality. In summary, findings from both simulated data and actual experiments demonstrate that the TRLS-based reconstruction method substantially improves the stability and reliability of differential Raman spectra reconstruction.