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Aggregation-Induced Absorption Enhancement for Deep Near-Infrared II Photoacoustic Imaging of Brain Gliomas In Vivo
摘要： The delineation of brain gliomas margins still poses challenges to precise imaging and targeted therapy, mainly due to strong light attenuation of the skull and high background interference. With deep penetration and high sensitivity, photoacoustic (PA) imaging (PAI) in the second near-infrared (NIR II) window holds great potential for brain gliomas imaging. Herein, mesoionic dye A1094 encapsulated in Arg-Gly-Asp-modified hepatitis B virus core protein (RGD-HBc) is designed and synthesized for effective NIR II PAI of brain gliomas. An aggregation-induced absorption enhancement mechanism is discovered in vitro and in vivo. It is also demonstrated that A1094@RGD-HBc, with an enhanced absorption in the NIR II window, displays ninefold PA signal amplification in vivo, allowing for precise PAI of the brain gliomas at a depth up to 5.9 mm. In addition, with the application of abovementioned agent, high-resolution PAI and ultrasensitive single photon emission computed tomography images of brain gliomas are acquired with accurate co-localization. Collectively, the results suggest great promise of A1094@RGD-HBc for diagnostic imaging and precise delineation of brain gliomas in clinical applications.
关键词： mesoionic dyes,brain gliomas,aggregation-induced absorption enhancement,second near-infrared window,deep photoacoustic imaging
更新于2025-09-23 15:22:29
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A Corrugated Plate Photocatalytic Reactor for Degradation of Waterborne Organic Contaminants
摘要： A UV-C/titanium dioxide (TiO2) plate coated photocatalytic reactor using a corrugated frame system was designed for water borne organic contaminant degradation. The anticipated advantages of using the corrugated layout include a larger photocatalytic surface area per unit volume and improved photocatalytic activity. The water distribution system was designed to assist effective interactions among the water pollutant, photocatalyst, and photons. The degradation of a methylene blue solution, as a model water contaminant, was carried out at room temperature (22 °C) at different concentrations and flowrates. With an 11 mg/L methylene blue solution, 70 % was degraded within the first 10 min using TiO2 coated corrugated plates, whereas under the same conditions the degradation rate was only 12 % for a corrugated reactor without a catalyst coating, and 4 % for a no-plate reactor. The methylene blue degradation was described by the Langmuir-Hinshelwood model, and the apparent photonic efficiency of the corrugated arrangement was found to be in the range of 1.53–2.83 % when half the initial concentration was degraded. The local area specific rate of energy absorption (LASREA) profile over the plates was determined from a model developed based on UV-C light irradiation distribution and plate configuration. Light intensity measurements were carried out and were found to correlate with this model. A set of corrugated plate photocatalytic reactors with different geometries, but with the same coated area, were then analyzed and absorbed UV light intensities were integrated to determine the best geometry.
关键词： corrugated photocatalytic reactor,light absorption modelling,reaction modelling
更新于2025-09-23 15:22:29
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Optical aptasensor based on silver nanoparticles for the colorimetric detection of adenosine
摘要： A new and straightforward optical sensor for the colorimetric determination of adenosine (AD) in human urine samples was developed. The sensor comprised silver nanoparticles (AgNPs) as colorimetric elements and anti-AD aptamer (AP) as a recognition probe. In a solution containing AD and high concentration of NaCl, due to the unique binding of AD with AP, the aggregated metal nanomaterials dispersed in the solution, and the color intensity of the solution was changed accordingly. The absorbance of the solution was monitored for AD quantification. The method was applicable for the determination of AD in the concentration range of 60–280 nM with the detection limit of 21 nM. The relative standard deviation ranged from 4.8 to 8.8% for six replicates. The method showed excellent selectivity toward AD checked over some probable interfering compounds. To investigate the performance of AgNPs, the analytical characteristics of the method including linear range, detection limit, selectivity, and precision were compared with those obtained by a common AuNPs-based aptasensor. The reliability of the method was further ascertained for the detection of AD in urine samples of two lung cancer patients with percentage recoveries in the range of 98–107%.
关键词： Adenosine,Silver nanomaterials,Colorimetric,UV–vis absorption spectroscopy,Aptamer
更新于2025-09-23 15:22:29
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Enzymatic method of urea determination in LTCC microfluidic system based on absorption photometry
摘要： In this paper a novel microanalytical system based on absorption photometry for urea determination in small-volume biological samples is described. The developed microsystem with built-in microreactor with urease immobilised on its surface was fabricated using low temperature co-fired ceramics (LTCC) technology. For detection of the ammonium ions – product of urea hydrolysis, the modified Berthelot’s reaction was applied and conditions of this reaction were optimised in a way to be suitable for analysis in microsystems and for particular application, with special regards to very small alternation of urea concentration in culture medium. The best results were obtained for reagent R1 composed of: 180 mM sodium salicylate, 15 mM sodium nitroprusside, 2 mM EDTA in phosphate buffer solution of pH 7 and reagent R2 containing 16.9 mM sodium hypochlorite in phosphate buffer solution of pH 12. Linear concentration range of urea detection with the use of the developed LTCC microfluidic system for the selected flow rate of 4 μl/min, was in the range up to 1 mM, and the calculated lower limit of detection – 0.002 mM. The developed microsystem enables urea determination in samples of post-culture medium and of cells lysates of minimised volume c.a. 1 μl. Preliminary studies related to determination of urea in real samples, performed using hepatic cells lysates and post-culture medium were successful. As reference methods, commercially available tests were applied. The determined urea concentration measured by means of the QuantiChrom? and BioMaxima test and by the developed method based on the LTCC microanalytical system differs by c.a. 9% and 2% respectively. To the best of our knowledge, this is the first urea analysis microsystem for use in cells culture studies characterised by: the smallest volume of sample – 1 μl, long lifetime with stable response - reduced by 14%, through experimental time span of 30 days as well as suitability for quasi-monitoring of cells in vitro with sampling rate - 6 samples per hour.
关键词： LTCC technology,enzymatic microreactor,microfluidic systems,lab-on-a-chip,enzymatic urea determination,absorption photometry
更新于2025-09-23 15:22:29
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Photodetachment, electron cooling, and recombination, in a series of neat aliphatic room temperature ionic liquids
摘要： Transient absorption following photodetachment of a series of neat methyl-alkyl-pyrrolidinium bis(trifluoromethylsulfonyl)amides at 6.20 eV was measured with sub-picosecond time resolution in the visible and near-IR portions of the spectrum. This series spans the onset of structuring in the liquids in the form of polarity alternation. Excitation promotes the electron into a delocalized state with a very large reactive radius. Strong transient absorption is observed in the visible spectrum with a ～700 fs lifetime, and much weaker, long-lived absorption is observed in the near-IR spectrum. Absorption in the visible is shown to be consistent with the hole, and absorption in the near-IR is assigned to the free solvated electron. Yield of free electrons is estimated at ～4%, is insensitive to the size of the cation, and is determined in less than 1 ps. Solvation of free electrons depends strongly on the size of the cation and correlates well with the viscosity of the liquid. In addition to radiolytic stability of the aliphatic cations, ultrafast, efficient recombination of separated charge in NTf2? based ionic liquids following photo-excitation near the band-gap may prevent subsequent reactive damage associated with anions.
关键词： solvated electron,electron cooling,recombination,photodetachment,ionic liquids,transient absorption
更新于2025-09-23 15:22:29
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Charge-state analysis of small barium-oxide clusters by X-ray absorption spectroscopy
摘要： Small barium-oxide clusters BamOn+ are studied by mass spectrometry and X-ray absorption spectroscopy to discuss stability of the clusters and oxidation state of constituent atoms. It is found that clusters with bulk composition, n = m, are stable, which can accommodate one or two excess oxygen atoms additionally as manifested by n = m + 1 and m + 2 species in the mass spectrum. XAS spectra of Ba2O2+ and Ba2O3+ reveal that the oxidation state of barium atoms stays at +2 (the bulk BaO value) even after binding excess oxygen, whereas spectral features originating from oxygen exhibit composition dependence. The present finding suggests that stoichiometric small barium-oxide clusters bind less-negatively-charged oxygen atoms without change in the charge state of barium.
关键词： X-ray absorption spectroscopy,charge state,barium-oxide clusters,oxidation number
更新于2025-09-23 15:22:29
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Chemical Identification of Single Ultrafine Particles Using Surface-Enhanced Infrared Absorption
摘要： In the past decade, it has been demonstrated that surface-enhanced infrared absorption (SEIRA) is a powerful method to enhance vibrational signals of thin molecular layers. Much less attention has so far been given to the possibility of using SEIRA for the detection and characterization of nanometer-sized particles, such as ultrafine dust particles. Here, we report on SEIRA measurements demonstrating that even one single particle with a deeply subwavelength dimension of less than 100 nm can be detected and chemically characterized with standard infrared microspectroscopy. Our approach is based on plasmonic resonances of bowtie-shaped Au apertures that are designed to extraordinarily enhance the material-specific phononic excitations of a nanometer-sized silica particle. We show that the bowtie geometry is especially suited for single-particle spectroscopy, as it combines the advantage of an intense electromagnetic hot spot, the size of which can be adjusted to the particle dimension, with easy positioning of ultrafine dust particles inside that hot spot. In agreement with numerical calculations, we show that a detection limit in terms of a particle diameter of less than 20 nm can be achieved, which corresponds to a ratio of the diameter to the vacuum wavelength below 0.002. Our approach offers the possibility of analyzing infrared bands from tiniest particles and thus paves the way toward SEIRA-based devices that can sense ultrafine dust.
关键词： SEIRA,chemical identification,ultrafine particles,plasmonics,bowtie nanoapertures,surface-enhanced infrared absorption
更新于2025-09-23 15:22:29
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Assessment of functionals for TDDFT calculations of one- and two-photon absorption properties of neutral and anionic fluorescent proteins chromophores
摘要： Performance of DFT functionals with different percentage of exact Hartree-Fock exchange energy (EX) is assessed for recovery of the CC2 reference one- (OPA) and two-photon absorption (TPA) spectra of fluorescent proteins chromophores in vacuo. The investigated DFT functionals, together with their EX contributions are: BLYP (0%), B3LYP (20%), B1LYP (25%), BHandHLYP (50%) and CAM-B3LYP (19% at short range and 65% at long range). Our test set consists of anionic and neutral chromophores as naturally occuring in the fluorescent proteins. For the first time, we compare TDDFT and CC2 methods for higher excited states, than the S1 state, exhibiting relatively large TPA intensity. Our TDDFT results for neutral chromophores reveal an increase of excitation energies as well as TPA and OPA intensities errors, compared to CC2-derived results, as the DFT functional contains less exact exchange. The long-range-corrected CAM-B3LYP functional performs the best, closely followed by BHandHLYP, while BLYP usually significantly underestimates all investigated spectral properties, hence being the worst in reproducing the reference CC2 results. The hybrid B3LYP and B1LYP functionals can be roughly placed in between. We propose that TDDFT may underestimate the TPA intensities for neutral chromophores of fluorescent proteins due to underestimated oscillator strengths between some excited states. In case of anionic chromophores, we find that B3LYP and B1LYP functionals overcome others in terms of reproducing CC2 excitation energies. On the other hand, however, TPA intensity is usually significantly underestimated and in this respect CAM-B3LYP functional seems to be again superior. In contrast to the case of neutral chromophores, it seems that large magnitude of excited-state dipole moment or change in dipole moment upon excitation may be the driving force behind high TPA transition moments.
关键词： fluorescent proteins chromophores,one-photon absorption,DFT functionals,two-photon absorption,TDDFT,CC2
更新于2025-09-23 15:21:21
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In situ high-pressure spectroscopic studies using moissanite (4H-SiC) anvils
摘要： We examined the Raman scattering and IR absorption spectroscopy of 4H-SiC and its performance as an anvil material for high-pressure UV-visible absorption spectroscopic measurements. The first- and second-order Raman peaks of 4H-SiC and diamond do not coincide. 4H-SiC does not have obvious signals from 2330-5000 cm-1, suggesting that 4H-SiC anvils are beneficial for high-pressure studies of samples whose Raman signals locate in the region of diamond. Above 1800 cm-1, the transmitted signal of 4H-SiC in the IR absorption spectra, measured through 4.6 mm thickness is much higher than that of type IIa diamond. An in situ high-pressure UV-visible absorption spectroscopy study on CdI2 was carried out up to 28.0 GPa using 4H-SiC anvil cells (4H-SAC) with a 400 μm culet and the acquired band gap narrowed with increasing pressure. These results show that 4H-SiC has an excellent performance in high-pressure spectroscopic studies.
关键词： IR absorption spectroscopy,high-pressure,UV-visible absorption spectroscopy,Raman spectroscopy,4H-SiC
更新于2025-09-23 15:21:21
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Pseudo-Continuous Flow FTIR System for Glucose, Fructose and Sucrose Identification in Mid-IR Range
摘要： In this paper, we present a new FTIR-based micro?uidic system for Glucose, Fructose and Sucrose detection. The proposed micro?uidic system is based on a pseudo-continuous ?ow coupled to a microscope-FTIR instrument. The detection and characterization of sugar samples were performed by recording their absorption spectrum in the wavelength range 700–1000 cm?1 of the Mid-IR region. The proposed pseudo-continuous ?ow system is designed to improve the uniformity of the sample distribution in the analyzed area versus conventional systems. The obtained results for different sugars concentrations, show a very low measurement error of 4.35% in the absorption peak intensity, which is ten times lower than the error obtained using the conventional measurements.
关键词： mid-IR absorption spectroscopy,absorption spectrum,FTIR spectroscopy,microscopy-FTIR spectrometer,sugars detection and quanti?cation,Glucose,Fructose,Sucrose,pseudo-continuous ?ow
更新于2025-09-23 15:21:21