Talanta Open最新文献

To address the limitations of natural enzymes, more and more artificial enzymes have been developed. As the most appropriate candidate, metal organic frameworks (MOFs) and MOFs-based derivatives have generated extensive interest due to their remarkable properties and potential applications in enzymes mimicry. In this work, Ce/Cu mixed metal oxides-carbon composite (CeCuO_x/C) was synthesized through a simple oxidation method with bimetallic MOFs CeCu-BTC as precursors. It was found that the prepared CeCuO_x/C possess four different enzyme-like activities, including peroxidase, oxidase, laccase and phosphatase mimetic activities. The kinetics parameters and potential influence factors of enzyme-like activities were studied and CeCuO_x/C exhibited high catalytic activity, excellent stability, and reusability. Additionally, a cysteine detecting method was established via oxidase-like activity of CeCuO_x/C. The linear response to the cysteine was in the range of 50 to 900 μM, and the limit of detection was 3.24 μM. The spiking recoveries were in the range 93.5–100.2 % for cysteine in artificial human urine samples and the relative standard deviations were found within the ranges of 1.2–2.9 %. This work presents a new approach for the design of multi-enzyme mimics and develops the potential of CeCuO_x/C for biological sensing.

In this overview, we explore the electroanalytical determination of the poisoner's poison: thallium. Thallium was named after the Greek word "thallos," meaning "green shoot" or "twig," due to its bright green spectral emission lines. It is toxic, tasteless, odourless and dissolves into water, and has been used by murderers as a challenging poison to detect and there is the need for the analytical determination of thallium. Laboratory based analytical instrumentation provide a routine methodology to measure thallium, but there is scope to develop in-the-field analytical measurements that are comparable to laboratory equipment and in some cases, they can provide even more sensitive analytical approaches. Electrochemistry can support such endeavours, where instrumentation are readily portable where electroanalytical sensors provide highly selective and sensitive outputs but yet are economical to support on-site analysis. In this review, we provide an electroanalytical overview of the current research directed toward the measurement of thallium and offer insights to future research.

Metal-oxide-semiconductors (MOS) gas sensors are widely used for detecting and measuring the concentration of various gases in different applications. Changing the electrical resistance when the MOS surface reacts with a specific gas is the basis of the operation of the gas sensor of MOS. They offer versatility in detecting various gases and fabricating them suitable for supervising energy efficiency, monitoring health and safety, and controlling hazardous emissions. However, traditional MOS sensors suffer from poor selectivity and usually require high operating temperatures. To overcome these limitations, researchers have explored strategies such as doping, bimetallic/co-doping, and composite structures with conductive polymers and 2D materials such as polyaniline (PANI), polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA), reduced graphene oxide (rGO), graphitic carbon nitride (g-C₃N₄), and graphene. Among the 2D materials, g-C₃N₄ stands out due to its distinct characteristics, including chemical stability, porosity structure, abundance, lack of toxicity, and numerous surface defects. The exfoliated structure and surface defects of g-C₃N₄ provide active sites for adsorbing atmospheric oxygen and facilitating reactions with specific gas molecules. This review introduces MOS gas sensors, covering their fabrication methods and electrical measurements. It then attentions on the properties of g-C₃N₄, synthesis methods, and its potential for composition with the MOS. The review highlights the enhanced gas sensing performance achieved by MOS/g-C₃N₄ nanocomposites to detect different gases.

Microphysiological systems (MPSs) have attracted increasing attention as a method for simulating in vitro drug efficiency. In particular, the interaction between liver and intestine tissues is one of the primary targets since they are closely involved in drug absorption and metabolism. However, most of the intestine-liver MPSs reported previously require pumps, electrodes, and porous membranes for co-culture of cells and evaluation of intestinal permeability (i.e., Trans-Epithelial Electrical Resistance, TEER), requiring complex manufacturing processes and operations. In this study, we report an all-polydimethylsiloxane (PDMS) co-culture microfluidic device, connecting microchamber-based paracellular transport assay on gut microtissues to liver tissues matured on the same device. On one side of the device, HepaRG cells are confined within thin parallel grooves that induce their differentiation into hepatocytes. The other side of the device is connected with microchannels to the liver side and includes the gut tissues, organized above microchambers. Such microchambers allow the evaluation of paracellular permeability by fluorescence imaging. Thanks to the microfluidic device we investigated changes in intestinal permeability induced by differentiated hepatocyte excretion and found that Caco-2 permeability was decreased when co-culture with HepaRG. Due to its simplicity and straightforward implementation, this method is anticipated as an innovative and efficient approach to assess tissue barrier function in multi-organ on-chip experiments.

Background

8-oxoguanine DNA glycosylase can maintain genomic stability and integrity. However, it can interfere with the regular DNA damage repair process, possibly leading to the development of cancer and various other human diseases when its activity becomes abnormal. Current methods for detecting 8-oxoguanine DNA glycosylase activity often suffer from low sensitivity, time-consuming procedures, labor-intensive requirements, and the need for specialized equipment and trained professionals for execution. Consequently, there is an urgent need for a portable, user-friendly 8-oxoguanine DNA glycosylase assay that offers swift results and supports real-time testing.

Results

We've developed a PERFUME method that combines primer exchange reaction and functionalized G-quadruplex/hemin DNAzyme for sensitive detection of Fpg, a typical 8-oxoguanine DNA glycosylase. Utilizing a single probe and T4 Polynucleotide Kinase (PNK) simplifies the experiment to a one-step reaction at 37 °C in 3 h, reducing sample consumption and improving sensitivity. We chose functionalized hemin cofactors, significantly improving catalytic efficiency and enhancing detection capability. This biosensor detects Fpg activity with a sensitivity as low as 0.11 U mL⁻¹, displaying exceptional sensitivity, selectivity, and interference resistance in human serum and bacterial cell extracts under isothermal conditions. The biosensor demonstrates remarkable selectivity and ability for Fpg inhibitors screening. In addition, this biosensor enables reading the sample's RGB values using a smartphone, facilitating accurate quantification of Fpg activity without the necessity for specialized equipment.

Significance

PERFUME simplifies Fpg detection by using a single hairpin and PNK in a one-step process. We utilize FUME to enhance catalytic efficiency, it surpassing the performance of traditional G-quadruplex/hemin DNAzyme methods. This approach excels in analyzing Fpg in human serum and bacterial extracts. It allows quantitative Fpg detection using UV–Vis and smartphones under isothermal conditions, making it valuable for clinical diagnosis.

The Fast Blue BB (FBBB) and 4-aminophenol (4-AP) colorimetric tests have been reportedly used for the qualitative determination of Δ⁹-THC in plants and for the differentiation between marijuana and hemp-type cannabis. We report the miniaturization of the FBBB colorimetric reaction on a silicone treated filter paper substrate and the analytical figures of merit for a quantitative determination of Δ⁹-THC for the first time. The reaction between Δ⁹-THC and FBBB forms a red chromophore that fluoresces when irradiated with visible (480 nm) or UV (365 nm) light, providing a 3-fold increase in sensitivity. Portable instruments are introduced for the objective color determination for both tests and for the fluorescence reading of the THC + FBBB complex. We report a fluorescence signal with Δ⁹-THC, Δ⁸-THC, and CBN. The limit of detection (LOD) was determined to be 1.6 ng/μL with precision ∼12 % RSD for standard Δ⁹-THC solutions ranging between 5 and 20 ng/μL. The linear dynamic range for this test is reported between 1.6 ng/μL and 20 ng/μL for the portable fluorescence detector. The miniaturization of both colorimetric tests and the increased sensitivity of the FBBB test using fluorescence analysis, coupled to portable instruments allows for limited quantitative analysis of cannabis plants in the field.

A novel selective membrane optode was prepared to determine of ultra-trace amounts of lead. This state-of-the-art optode amalgamates a bespoke ionophore, 4-(thiazol-2-yldiazenyl)benzene-1,3-diol (TDBD), with ETH-5294, assuming the role of a chromoionophore. This potent composition converges with sodium tetraphenylborate (NaTPB) and dioctyl phthalate (DOP), harmoniously enclosed within a matrix of poly(vinyl chloride) (PVC). The influence of various parameters on the preparation of the optode and the determination of Pb²⁺ was investigated and optimized. Evidently, the optode unfurls an expansive linear dynamic expanse, spanning an astonishing range from 6.0 × 10⁻⁹ to 8 × 10⁻⁵ M. Remarkably, it retains an astonishingly low degree of detection and quantification, registering at 1.75 and 5.85 × 10⁻⁹ M, respectively. The response time of the optode was 4.0 min. The optodes versatility extends its embrace towards rejuvenation, permitting multiple rounds of service via 0.2 M HNO₃ solutions. The effect of potential interference ions on the Pb²⁺ determination was illustrated. The results showed that the prepared optode was very selective to lead ions so that it had no significant response to common ions such as Mg²⁺, Mn²⁺, Cd²⁺, Ni²⁺, Fe²⁺, Fe³⁺, Hg²⁺, Cu²⁺, and Co²⁺. The optode was applied successfully to determine of Pb²⁺ indifferent food, biological and environmental samples and result obtained is comparable to atomic absorption spectrometry method.

In this work, four metal-organic frameworks (MOFs) including DUT-4, DUT-8, IRMOF-8, and MIL-140B were synthesized using 2,6-naphthalene dicarboxylic acid as organic ligand and Al³⁺, Co²⁺, Zn²⁺, and Zr⁴⁺as metal centers, then coated on stainless steel wires as solid-phase microextraction (SPME) fiber coatings. Five aldehyde biomarkers (hexanal, heptanal, octanal, decanal, and nonanal) in exhaled breath of lung cancer patients were used as the target analytes, and extracted using four MOFs fiber coatings, followed by thermal desorption and quantitative analysis using GC–MS. The DUT-4 was found to be the most appropriate sorbent. The developed SPME-GC–MS method has large enrichment factors (877–1711), wide linear ranges (0.5–1000 μg L⁻¹), and low detection limits (0.056–0.138 μg L⁻¹). The relative standard deviation for six replicate cycles using one DUT-4 coated fiber were 2.0–7.7 % (intra-day) and 2.2–4.6 % (inter-day), respectively. The fiber-to-fiber reproducibility for three parallel prepared fibers was in the range of 3.7–13.7 % (RSD). The fabricated DUT-4 coated fiber can withstand at least 100 cycles of extraction/desorption/conditioning without significant loss of extraction efficiency and precision. The high enrichment factors of the DUT-4 coatings are attributed to the high specific surface area, unique porous structure, and abundant aluminum coordinated unsaturated metal sites of the DUT-4 material. Moreover, the 2,6-naphthalene dicarboxylic acid has two benzene rings with a 180° orientation, which not only increases the hydrophobicity of the MOFs material to avoid water molecules occupying adsorption sites and helps to form a rigid skeleton structure with a large number of functional adsorption sites on the surface, thereby improving the enrichment factor of target analytes. Ultimately, the developed DUT-4 coated SPME fibers was sucessfully used for the analysis of exhaled breath samples, and the recoveries for the spiked analytes were in the range of 89–105 %.

Polymer oxidation affects the molecular structure and decides the performances, making its rapid and sensitive diagnosis important for evaluating the state of polymer materials and predicting its service life. In this study, fluorometric analysis of the oxidation of hyperbranched polyethyleneimine is realized by Schiff-base reaction. The sensing mechanism is due to the oxidation-mediated generation of oxygen-containing groups, which react with residual primary amine and produce fluorescent Schiff-base compounds. Four hPEIs with different molecular weight possess similar fluorescence variation during oxidation, demonstrating the universality of the proposed technique. Moreover, the successful quality assessment of hPEI verifies the practical application of the proposed fluorescence-based self-diagnosis technique.

The use of vaporizers to inhale cannabis is a technique that has risen in popularity among the American public. There is a general perception that vaporizers are “safer” when compared to more traditional cannabis smoking via combustion (i.e., cigarettes). The inherent use of heated air in vaporizers might reduce the respiratory toxicants or protein toxins by heating cannabis to a temperature where active compounds form in vapor phase. Yet this temperature is below the point of combustion where smoke and associated toxicants are produced. The elemental impurities are a general concern in all botanical products including cannabis and cannabis-derived products (CCDPs). This study aimed to investigate the potential transfer of those metallic elements from cannabis material to cannabis vapor through the vaporization process. A Volcano Digit Vaporizer (Storz & Bickel) was used as the heating device to perform the vaporization. Three cannabis plant materials were evaluated with varying contents of cannabinoids, including a cannabis placebo (<0.01 % Tetrahydrocannabinol (THC), Cannabidiol (CBD) & Cannabinol (CBN)), cannabis with low potency (2.0 % THC/ 0.02 % CBD/ 0.47 % CBN) and high potency (6.7 % THC/ non detectable CBD/ 0.49 % CBN). Baseline elemental impurity levels were evaluated for all cannabis plant materials. Four different types of heat treatment, namely no heat, 30 seconds (s), and 70 s heat treatment, and finally 70 s heat treatment with air flow, were developed for the three cannabis materials and the experimental samples after vaporization were analyzed by an inductively coupled plasma-mass spectrometry (ICP-MS) system. The results showed that sixteen elemental impurities were detected, and all have similar concentration, between 10 ng/g and 8 × 10⁶ ng/g, in the three types of cannabis materials, where Mg was measured with the highest content. Within the four heating treatments evaluated no significant changes of these metallic elements (elemental impurities) were found when compared to the plant materials. This preliminary experimental study evaluated a single vaporizer and three cannabis plant materials suggesting a transfer of metallic elements from cannabis material to cannabis vapor may not occur during the vaporization process under these study conditions.