Silicon quantum dots based fluorescent probes for detecting methyl parathion pesticide residues in potato, tap water and Yellow River.

In this paper, a novel ratiometric fluorescent probe based on silicon quantum dots (SiQDs) has been developed for the sensitive detection of methyl parathion pesticide residues. The silicon quantum dots were prepared by a simple hydrothermal reaction process using 3-Aminopropyltriethoxysilane (APTES) as silicon resource and were characterized by the analysis of transmission electron microscopy, FTIR spectroscopy, and X-ray photoelectron spectroscopy. The silicon quantum dots displayed characteristic blue fluorescence emission at 440 nm. Tyrosinase can catalyze the oxidation of tyramine to form dopamine. Then, dopamine can interact with silicon quantum dots and effectively change the position of its fluorescence emission for redshifting to 540 nm. In the presence of organic phosphorus pesticides (OPPs), the activity of tyrosinase was inhibited, resulting in the inability to generate dopamine and the fluorescence emission at 440 nm remaining unchanged. As a model of organic phosphorus pesticides, methyl parathion (MP) was determined using this method, and the fluorescence intensity response values showed a good linear relationship with methyl parathion concentration in the range of 50-90 nM, with a detection limit of 0.149 nM. Due to its good performance of relative low detection limit, good selectivity and high reproducibility, this sensing system has been successfully applied to the detection of methyl parathion in environmental water samples and potato samples, which showed good prospects for application in the detection of organic phosphorus pesticide residues in more real samples.

High-Intensity Focused Ultrasound Enhances Drug Penetration into the Human Skin in the Franz Diffusion Cell.

Purpose: High-intensity focused ultrasound (HIFU)-assisted drug delivery is a non-invasive tool to deliver drugs to targeted areas, currently used mainly for treating cancer and cardiovascular diseases. However, in terms of transdermal drug delivery, HIFU technology is still poorly understood. Accordingly, this study sought to investigate the effectiveness of HIFU on drug penetration into the skin using human skin tissues. Methods: Gel-type drugs whose ingredient is glutathione were labelled with fluorescein isothiocyanate, in turn the drugs were allowed to penetrate to the human skin tissue in the Franz diffusion cell for 24 hours in control and HIFU treatment groups, and their fluorescence intensity was measured using a multiple microplate reader at one, two, six, and 24 hours after drug application. In addition, tissue slice analysis was performed in each tissue slice at 24 hours post-drug application. The % area, fluorescence intensity per area, and penetration depth of the drug were measured using a fluorescence microscope. Results: The fluorescence intensity increased with time in all groups. Specifically, at 24 hours after drug application, the fluorescence intensity (a.u). of the 10-shot HIFU treatment group was significantly enhanced compared to that of the control group (p < 0.05). The tissue slice analysis demonstrated that the % area of fluorescent drug and the fluorescence intensity per area (a.u.) were all significantly increased in both HIFU treatment groups compared to the control group (p < 0.05, p < 0.001). In addition, the penetration depth (µm) also markedly rose in both HIFU treatment groups compared to the control group (p < 0.01, p < 0.05). Conclusion: It was demonstrated for the first time that HIFU significantly facilitated topical drug penetration into the human skin, strongly implying that HIFU can be a useful option for transdermal drug delivery.

Spectroscopic Study of a Novel Binaphthyl Amine Fluorescent Probe for Chiral Recognition of D/L-Lysine.

Lysine plays a crucial role in promoting development, enhancing immune function, and improving the function of central nervous system tissues. The two configurational isomers of amino acids have significantly different effects. Currently, methods for chiral recognition of lysine have been reported; however, previous detection methods have drawbacks such as expensive equipment and complicated detection processes. Fluorescence analysis, on the other hand, boasts high sensitivity, strong selectivity, and simple operation. In this study, we synthesized four novel Binaphthyl-Amine (BINAM)-based fluorescent probes capable of specifically identifying the L-configuration of lysine among the twenty amino acids that constitute human proteins. The enantiomeric fluorescence enhancement ratio (ef or ΔIL/ΔID) reached up to 15.29, demonstrating high enantioselectivity. In addition, we assessed the probe's recognition capabilities under varying pH levels, reaction times, and metal ion conditions, along with its limit of detection (LOD) and quantum yield. Our results suggest that this probe serves as a highly stable tool for the detection of chiral lysine.

Selenium deposition in an atypically disintegrated hoof wall in a Thoroughbred racehorse with alkali disease: Proof by energy-dispersive X-ray fluorescence analysis.

From summer 2018 to summer 2019, several Thoroughbred racehorses held at the Miho Training Centre of the Japan Racing Association inadvertently ingested excessive amounts of sodium selenite, resulting in typical chronic selenium (Se) poisoning - the so-called alkali disease. The typical abnormality was a hoof wall disorder with a circumferentially deep ring and/or transverse hoof wall cracks parallel to the coronet on all feet and appearing after excessive ingestion. One affected Thoroughbred male was unique in that all the hooves had a rough surface with a very fragile hoof wall, but no wall rings or transverse cracking. This horse was euthanized because of dysstasia due to the permanent foot pain associated with hoof wall deformities in the front feet. To detect Se deposition in the hooves, we used energy-dispersive X-ray fluorescence (EDXRF) analysis to measure the Se signal intensity of each lesion. Characteristic Se-kα signals were emitted from the areas of histologically damaged hoof wall at 33.76 ± 11.78 (mean ± SD) counts per second (cps)/mm2. In contrast, the signal from the uninjured proximal hoof wall was 1.43 ± 0.14 cps/mm2 and that from the uninjured distal hoof wall was 1.51 ± 0.23 cps/mm2. The much greater Se deposition in the injured hoof walls suggests that their disintegration was caused by alkali disease. These results indicate that atypical hoof wall abnormalities due to alkali disease can be diagnosed by EDXRF analysis.

Metal-enhanced fluorescence (MEF) effect based on silver nanoparticles with different UV spectra on a surface carbon dot-based novel dry platform.

In this work, to enhance the fluorescence quantum yield of carbon dots (CDs), a novel metal-enhanced fluorescence (MEF) structure was designed by decorating CDs on silver nanoparticle (AgNPs) film. The glass slide-AgNPs (GS-AgNPs) structure was fabricated using the electrostatic adsorption method, and the AgNPs-CDs structures were prepared by the direct drying method, which then formed the GS-AgNPs-CDs composite structure. In this structure, the MEF effect was found to be size dependent by changing the 5 types of AgNPs with different sizes. And the MEF effect also decreased as the distance between the AgNPs and CDs increased by using polyvinylpyrrolidone (PVP) to separate the AgNPs and CDs. This hybrid structure can be used as a fluorescence detection platform and the recorded fluorescence intensity of GS-AgNPs 428 nm-CDs achieved a maximum enhancement factor (EF) of 31.72. Considering the high enhancement factor, this system may become promising to find potential applications in biochemical assay fields.

Study on the mechanism of ultrasonic cavitation effect on the surface properties enhancement of TC17 titanium alloy.

In industrial production and scientific research, ultrasonic cavitation technology, with its outstanding physical and chemical processing capabilities, has been widely applied in fields such as material surface modification, chemical synthesis, and biotechnology, becoming a focal point of research and application. This article delves into the effects of different ultrasonic frequencies on cavitation outcomes through the combined use of numerical simulation, fluorescence analysis, and high-speed photography, specifically analyzing the quantitative improvement in the mechanical properties of TC17 titanium alloy under ultrasonic cavitation at frequencies of 20 kHz, 30 kHz, and 40 kHz. The study found that at an ultrasonic frequency of 20 kHz, the maximum expansion radius of cavitation bubbles can reach 51.4 µm, 8.6 times their initial radius. Correspondingly, fluorescence intensity and peak area also increased to 402.8 and 28104, significantly above the baseline level. Moreover, after modification by ultrasonic cavitation, the original machining marks on the surface of TC17 titanium alloy became fainter, with the emergence of new, uniformly distributed microfeatures. The microhardness of the material increased from 373.7 Hv to 383.84 Hv, 396.62 Hv, and 414.06 Hv, with a maximum improvement of 10.8 %. At the same time, surface height difference and roughness significantly decreased (to 3.168 µm and 0.61 µm respectively), with reductions reaching 45.1 % and 42.4 %, indicating a significant improvement in material surface quality. Notably, there is a negative correlation between the improvement of mechanical properties and ultrasonic frequency, suggesting that the improvement effects decrease as ultrasonic frequency increases. This research not only reveals the quantitative relationship between ultrasonic cavitation frequency and material surface modification effects but also provides a solid scientific basis and practical guidance for the application of ultrasonic cavitation technology in surface engineering, signifying the technology's potential for broad application in the future.

Computational Hyperspectral Microflow Cytometry.

Miniaturized flow cytometry has significant potential for portable applications, such as cell-based diagnostics and the monitoring of therapeutic cell manufacturing, however, the performance of current techniques is often limited by the inability to resolve spectrally-overlapping fluorescence labels. Here, the study presents a computational hyperspectral microflow cytometer (CHC) that enables accurate discrimination of spectrally-overlapping fluorophores labeling single cells. CHC employs a dispersive optical element and an optimization algorithm to detect the full fluorescence emission spectrum from flowing cells, with a high spectral resolution of ≈3 nm in the range from 450 to 650 nm. CHC also includes a dedicated microfluidic device that ensures in-focus imaging through viscoelastic sheathless focusing, thereby enhancing the accuracy and reliability of microflow cytometry analysis. The potential of CHC for analyzing T lymphocyte subpopulations and monitoring changes in cell composition during T cell expansion is demonstrated. Overall, CHC represents a major breakthrough in microflow cytometry and can facilitate its use for immune cell monitoring.

Enhancement of mineral density and mechanical properties in root caries treated with silver diammine fluoride and glass ionomer cement, with emphasis on silver ion distribution.

OBJECTIVES: This study aimed to measure the distribution of silver ion (Ag+), mineral recovery, and nanohardness in carious lesions and comprehensively evaluate the degree of dentin restoration. METHODS: Sixty human teeth with root caries were randomly assigned to the control, silver diammine fluoride (SDF) [Safo], and SDF+Glass ionomer cement (GIC) treatment [Safo+Fuji] groups. Micro-computed tomography (micro-CT) was performed at five time points for each sample before/after treatment to evaluate mineral density within and around carious lesions. Three months following treatment, 12 samples were selected for synchrotron radiation X-ray fluorescence analysis to evaluate Ag+ distribution, while 15 samples were selected for nanoindentation. Data were analyzed using Dunnett's T3 test for micro-CT and Wilcoxon rank sum test with Bonferroni correction (p = 0.017) for nanoindentation. The correlation between hardness and mineral change was analyzed using the Spearman rank correlation coefficient. RESULTS: The Safo and Safo+Fuji groups showed significantly higher mineral recovery rates than did the control group (p < 0.001). In the Safo group, Ag+ accumulated in the deeper layers rather than the superficial layer of caries. In the Safo+Fuji group, Ag+ was found evenly distributed throughout caries, with only a few Ag+ detected in the GIC layer. Hardness in the Safo+Fuji group was significantly higher compared with the Safo group at depths in the range of 10-50 µm. CONCLUSION: In the presence of GICs, SDF exhibited high remineralization capacity when diffusing throughout carious lesions over time. Combined treatment with SDF and GIC could strengthen root dentin even in the presence of caries. CLINICAL SIGNIFICANCE: We found that combination treatment with SDF and GIC could increase mineral density in caries and improve the hardness of the tooth structure compared with fluoride-based agents alone. These findings might pave the way for future clinical trials to determine the therapeutic potential of nanotechnology-based restorative materials.

Inhibitory Activity of Quercetin, Rutin, and Hyperoside against Xanthine Oxidase: Kinetics, Fluorescence, and Molecular Docking.

INTRODUCTION: Quercetin (Qc), rutin (Ru), and hyperoside (Hyp) are three common polyphenols widely distributed in the plant kingdom. METHOD: This study explored the inhibition and mechanisms of Qc, Ru, and Hyp against xanthine oxidase (XOD) by enzyme kinetic analysis, fluorescence analysis, and molecular docking. The inhibitory activities of the three polyphenols on XOD showed the following trend: quercetin > hyperoside > rutin, with IC50 values of 8.327 ± 0.36 µmol/L, 35.215 ± 0.4 µmol/L and 60.811 ± 0.19 µmol/L, respectively. All three polyphenols inhibited xanthine oxidase activity in a mixed-competitive manner. Synchronous fluorescence results demonstrated that three polyphenols binding to XOD were spontaneous and showed static quenching. RESULT: The binding of the three polyphenols to XOD is mainly driven by hydrogen bonding and van der Waals forces, resulting in the formation of an XOD-XA complex with only one affinity binding site. The binding sites of the three RSFQ phenolic compounds are close to those of tryptophan. Molecular docking showed that all three polyphenols enter the active pocket of XOD and maintain the stability of the complex through hydrogen bonding, hydrophobic interaction, and van der Waals forces. CONCLUSION: The results provide a theoretical basis for quercetin, rutin, and hyperoside to be used as function factors to prevent hyperuricemia.

A ratiometric fluorescence probe for bisulfite detection in live cells and meat samples.

The development of reliable probe technology for the detection of bisulfite (HSO3-) in situ in food and biological samples is contributing significantly to food quality and safety assurance as well as community health. In this work, a responsive probe, EHDI, is developed for ratiometric fluorescence detection of HSO3- in aqueous solution, meat samples, and living cells. The probe is designed based on the HSO3- triggered 1,4-addition of electron deficit C = C bond of EHDI. As a result of this specific 1,4-addition, the π-conjugation system was destructed, resulting in blue shifts of the emission from 687 to 440 nm and absorption from 577 to 355 nm. The probe has good water solubility, high sensitivity and selectivity, allowing it to be used for imaging of HSO3- internalization and production endogenously. The capability of probe EHDI for HSO3- was then validated by traditional HPLC technology, enabling accurately detect HSO3- in beef samples. The successful development of this probe thus offers a new tool for investigating HSO3- in situ in food and biological conditions.

Pharmacognostic standardization and evaluation of antiulcer potential of Olax psittacorum leaf extract.

The modern medicine has received many plants as a gift from ethnobotany. It is an efficient method of discovering new medicines. The leaves of Olax psittacorum (Lam.) Vahl. were extracted with ethanol, and the phytoconstituents present in the leaf extract were identified using Gas chromatography-mass spectrometric analysis (GC-MS), followed by determination of physico-chemical parameters and anti-ulcer properties. The leaf ethanolic extract (LEE) yield was observed to be 43.2%. The quantitative surface microscopy analysis revealed a stomatal index of 30 and 22 epidermal cells and qualitatively confirms presence of quinone, flavonoid, phenol, carbohydrate, tannin, saponin and absence of alkaloids using various screening techniques. The LEE confirms its anti-ulcer potency by inhibiting ulceration by 58% and 75% respectively, thus proving the hypothesis. These identified parameters may be helpful in developing some botanical standards for the standardisation and identification of O. psittacorum leaves with anti-ulcer properties.

Antibacterial Activity of Plant Polyphenols Belonging to the Tannins against Streptococcus mutans-Potential against Dental Caries.

Dental caries (DC) is the most common oral pathology. The main bacteria responsible for DC is Streptococcus mutans. One of the strategies that can decrease or eliminate the risk of DC development is using compounds that will inhibit both the growth and virulence factors of S. mutans. Tannins are plant polyphenols that have strong antibacterial activity. The purpose of this study was to assess the antibacterial activity of three tannins against S. mutans. In this investigation, microbiological tests (MIC and MBC) and physicochemical techniques like the fluorescence measurements of tannins' interaction with S. mutans cell membrane and membrane proteins, zeta potential, and thermodynamic analyses were used to obtain knowledge about the antibacterial potential of the investigated compounds against S. mutans as well as about the mechanisms associated with antibacterial activity. The obtained results demonstrate that the used compounds exhibit high antibacterial activity against S. mutans. The mechanisms of their antibacterial activity are linked to the strong change in the S. mutans membrane fluidity and potential, and to their interaction with membrane proteins that can result in great disturbance of bacterial physiology and ultimately the inhibition of bacterial growth, triggering their death. Therefore, it can be concluded that the investigated compounds can be potentially used as natural factors in the prevention of dental caries.

Radical generation and bactericidal activity of nanobubbles produced by ultrasonic irradiation of carbonated water.

Our previous study showed that nanobubbles (NBs) encapsulating CO2 gas have bactericidal activity due to reactive oxygen species (ROS) (Yamaguchi et al., 2020). Here, we report that bulk NBs encapsulating CO2 can be efficiently generated by ultrasonically irradiating carbonated water using a piezoelectric transducer with a frequency of 1.7 MHz. The generated NBs were less than 100 nm in size and had a lifetime of 500 h. Furthermore, generation of ROS in the NB suspension was investigated using electron spin resonance spectroscopy and fluorescence spectrometry. The main ROS was found to be the hydroxyl radical, which is consistent with our previous observations. The bactericidal activity lasted for at least one week. Furthermore, a mist generated by atomizing the NB suspension with ultrasonic waves was confirmed to have the same bactericidal activity as the suspension itself. We believe that the strong, persistent bactericidal activity and radical generation phenomenon are unique to NBs produced by ultrasonic irradiation of carbonated water. We propose that entrapped CO2 molecules strongly interact with water at the NB interface to weaken the interface, and high-pressure CO2 gas erupts from this weakened interface to generate ROS with bactericidal activity.

Ligand "switching on" fluorescence of HIV-1 RNA-templated copper nanoclusters for ligand-RNA interaction assays.

Ligand-RNA interaction assay provides the basis for developing new RNA-binding small molecules. In this study, fluorescent copper nanoclusters (CuNCs) were first prepared using two kinds of HIV-1 RNA targets, rev-responsive element (RRE) and transactivator response element (TAR) RNA, as new templates, and it was found that the fluorescence of the single RNA-templated CuNCs was negligible. Using neomycin as a model drug, the fluorescence could be augmented (approximately 6 times) for the neomycin/RNA-templated CuNCs. Thus, a novel method was developed for ligand-RNA interactions by observing the fluorescence changes in CuNCs prepared using RNA before and after the addition of ligands. The preparation parameters of neomycin/RNA-CuNCs were optimized. The as-prepared CuNCs were characterized using UV-vis spectroscopy, fluorescence spectroscopy, and high-resolution transmission electron microscope. Circular dichroism spectral analysis showed that RRE and TAR were inclined to form a double-stranded structure after interaction with neomycin, which was more conducive to the formation of CuNCs. The interactions of neomycin and three test drugs (amikacin, gentamicin, and tobramycin) with RNA were investigated using the proposed method, and the binding constants and number of binding sites were obtained through theoretical calculations. This study provides a novel approach for ligand-RNA interaction assays.

Biosensor analysis technology and its research progress in drug development of Alzheimer's disease / 药学学报

Biosensor analysis technology is a kind of technology with high specificity that can convert biological reactions into optical and electrical signals. In the development of drugs for Alzheimer's disease (AD), according to different disease hypotheses and targets, this technology plays an important role in confirming targets and screening active compounds. This paper briefly describes the pathogenesis of AD and the current situation of therapeutic drugs, introduces three biosensor analysis techniques commonly used in the discovery of AD drugs, such as surface plasmon resonance (SPR), biolayer interferometry (BLI) and fluorescence analysis technology, explains its basic principle and application progress, and summarizes their advantages and limitations respectively.

Structural and functional characterization of cold-active sialidase isolated from Antarctic fungus Penicillium griseofulvum P29.

The fungal strain, Penicillium griseofulvum P29, isolated from a soil sample taken from Terra Nova Bay, Antarctica, was found to be a good producer of sialidase (P29). The present study was focused on the purification and structural characterization of the enzyme. P29 enzyme was purified using a Q-Sepharose column and fast performance liquid chromatography separation on a Mono Q column. The determined molecular mass of the purified enzyme of 40 kDa by SDS-PAGE and 39924.40 Da by matrix desorption/ionization mass spectrometry (MALDI-TOF/MS) analysis correlated well with the calculated mass (39903.75 kDa) from the amino acid sequence of the enzyme. P29 sialidase shows a temperature optimum of 37 °C and low-temperature stability, confirming its cold-active nature. The enzyme is more active towards α(2 â†’ 3) sialyl linkages than those containing α(2 â†’ 6) linkages. Based on the determined amino acid sequence and 3D structural modeling, a 3D model of P29 sialidase was presented, and the properties of the enzyme were explained. The conformational stability of the enzyme was followed by fluorescence spectroscopy, and the new enzyme was found to be conformationally stable in the neutral pH range of pH 6 to pH 9. In addition, the enzyme was more stable in an alkaline environment than in an acidic environment. The purified cold-active enzyme is the only sialidase produced and characterized from Antarctic fungi to date.

Short-Term and Long-Term Effects after Exposure to Ionizing Radiation and Visible Light on Retina and Retinal Pigment Epithelium of Mouse Eye.

A comparative in vivo study of the effects of ionizing radiation (accelerated protons) and visible light (400-700 nm) on the retina and retinal pigment epithelium (RPE) of the mouse eye was carried out. Using the methods of fluorescence spectroscopy and high-performance liquid chromatography (HPLC), we analyzed the relative composition of retinoids in chloroform extracts obtained from the retinas and RPEs immediately after exposure of animals to various types of radiation and 4.5 months after they were exposed and maintained under standard conditions throughout the period. The fluorescent properties of chloroform extracts were shown to change upon exposure to various types of radiation. This fact indicates the accumulation of retinoid oxidation and degradation products in the retina and RPE. The data from fluorescence and HPLC analyses of retinoids indicate that when exposed to ionizing radiation, retinoid oxidation processes similar to photooxidation occur. Both ionizing radiation and high-intensity visible light have been shown to be characterized by long-term effects. The action of any type of radiation is assumed to activate the mechanism of enhanced reactive oxygen species production, resulting in a long-term damaging effect.

Detection of Doxycycline Using Carbon Quantum dots as Probe Based on Internal Filtering Effect.

The establishment of a convenient and effective detection method for doxycycline (DC) holds significant importance in drug monitoring and drug residue assessment. In this work, carbon quantum dots (CQDs) with excellent and stable luminescence performance (the quantum yield of CQDs was 21.8%) were synthesized by the melting method and employed as probes to monitor the fluorescence intensity variations before and after the introduction of DC. A fluorescence analytical method based on the internal filtration effect (IFE) was developed for DC determination. The mechanism of DC quenching CQDs was verified using fluorescence lifetime tests, absorption spectroscopy, and evaluation of internal filtration parameters. After optimizing experimental conditions, it was found that the DC concentration (CDC) exhibited a good linear relationship with the fluorescence quenching efficiency ((F0-F)/F0) of CQDs in the range of 5-30 µM. The fitted linear equation was Y = 0.01249*CDC+0.03625, R2 = 0.9987, and the detection limit was 2.343 µM (n = 8). This developed method has been successfully applied to accurately determine DC concentrations in both doxycycline hydrochloride tablets and human serum samples. It stands out for its simplicity, rapidity, and acceptable detection performance. Due to its advantages, this method holds great promise for application in the biomedical field for monitoring DC drug concentrations and ensuring quality control.

The ratiometric fluorescent sensor based on the mixture of CdTe quantum dots and graphene quantum dots for quantitative analysis of silver in drinks.

Silver nanoparticles can be used in antibacterial packaging or disinfection. Research has shown that sugary fluid induces the leaching of silver nanoparticles into water, which may be harmful to humans. Single wavelength fluorescence analysis has been used for quantitative analysis of silver nanoparticles but suffers from low specificity and poor anti-interference ability. In this paper, a ratiometric fluorescence sensor system (GCS) was used for the detection of Ag+, which realized both visual detection and quantitative analysis of silver in drinks. The color changes of GCS with different concentrations of Ag+ are distinguishable and easy to analyze. There is also a good linear relationship between the concentrations of Ag+ and varieties of F424 nm/F570 nm, and the lowest detection limit reached 0.2266 nmol/L. This GCS shows good selectivity and recovery and could be used for the detection of Ag+ in drink samples.

Confocal micro X-ray fluorescence analysis for the non-destructive investigation of structured and inhomogeneous samples.

Confocal micro X-ray fluorescence (CMXRF) spectroscopy is a non-destructive, depth-resolved, and element-specific technique that is used to analyze the elemental composition of a sample. For this, a focused beam of mono- or polychromatic X-rays is applied to excite the atoms in the sample, causing them to emit fluorescence radiation which is detected with focusing capillary optics. The confocal design of the instrument allows for depth-resolved analysis, in most cases with a resolution in the lower micrometer dimension after collecting X-rays from a predefined volume within the sample. The element-specific nature of the technique allows information to be obtained about the presence and concentration of specific elements in this volume. This makes CMXRF spectroscopy a valuable tool for a wide range of applications, especially when samples with an inhomogeneous distribution of elements and a relatively light matrix have to be analyzed, which are typical examples in materials science, geology, and biology. The technique is also commonly used in the art and archaeology fields to analyze the elemental composition of historical artifacts and works of art, helping to provide valuable insights into their provenance, composition, and making. Recent technical developments to increase sensitivity and efforts to improve quantification in three-dimensional samples will encourage wider use of this method across a multitude of fields of application in the near future. Confocal micro X-ray fluorescence (CMXRF) is based on the confocal overlap of two polycapillary lens foci, creating a depth-sensitive and non-destructive probing volume. Three-dimensional resolved element distribution images can be obtained by measuring the fluorescence intensity as function of the three-dimensional position.