Analytical Chemistry最新文献

The rapid diagnosis of bloodstream infections is essential for guiding targeted treatment, reducing antibiotic resistance, and improving patient outcomes. We report an integrated centrifugal microfluidic point-of-care low-cost chip for simultaneous detection of six types of pathogen nucleic acid in 50 min. All of the reagents were prestored in dry powder form inside the microfluidic chip for real-time fluorescence loop-mediated isothermal amplification. Through a simple lysis and dilution process, clinically positive blood culture samples from patients can be loaded into the microfluidic chip for pathogen nucleic acid identification. The developed method demonstrated high consistency with the standard method used by the hospital in the testing of 120 clinical patient samples. It is envisioned that this work may provide a useful platform for rapid diagnosis of bloodstream infections by identification of pathogen nucleic acid.

DNA damage refers to chemical alterations in genomic DNA arising from endogenous or exogenous factors, and delineating the types and levels of these lesions is essential for elucidating the molecular mechanisms and regulatory networks underlying DNA repair. However, current methods are limited to one specific type of damage and often rely on DNA extraction and in vitro processing, which fails to capture the spatial distribution of diverse DNA damages within cellular context. Here we present intracellular strand break end extension-encoded amplification (ISBEA), an in situ imaging strategy that enables simultaneous visualization of multiple DNA lesion types. ISBEA uses a sequential enzymatic workflow in which glycosylases, endonucleases and exonucleases selectively recognize oxidized purines, AP sites and strand breaks, converting them stepwise into uniform 3'-hydroxyl termini. These activated termini undergo programmable extension and serve as primers to initiate DNA-encoded amplification, ultimately generating fluorescence signals present to each damage type. With spatially resolved visualization of diverse DNA damages within cells, ISBEA provides a robust platform for investigating the origins, repair pathways and biological consequences of DNA damage, offering valuable methodological support for advancing the understanding of genome stability maintenance and the development of related diseases.

Aiming to meet the critical need for user-friendly and sensitive clinical analysis platforms, an all-in-capillary SERS analytical system integrated with a visible-light-enhanced nanozyme for highly sensitive and convenient biomarker detection was developed. The system employs a hierarchical tandem heterojunction (TiO₂/MoS₂/CoFe₂O₄) as a peroxidase-like nanozyme, which significantly enhances separation and transfer of photogenerated charges under visible light. This nanozyme catalyzes the oxidation of leucocrystal violet to crystal violet, generating a characteristic Raman signal at 923 cm^-1. To ensure analytical reliability, the inner wall of the capillary was modified with TiO₂ as an internal standard, enabling signal self-calibration. This integrated platform allows direct sampling of finger blood without any pretreatment, performing all-in-capillary SERS detection. The proposed method achieves ultrasensitive detection of Alzheimer's disease biomarker Aβ_1-42, with a wide linear range of 1.0 × 10^-3 to 1.0 × 10^-7 μg/mL, a low detection limit of 0.089 pg/mL, and satisfactory recovery of 94.3%-101% in human serum. The method was successfully applied to clinical serum samples from Alzheimer's patients and controls of different groups, revealing statistically significant differences in Aβ_1-42 levels. Furthermore, the results showed excellent agreement with those obtained by the reference ELISA method, demonstrating high accuracy and practical applicability of our assay for early diagnosis and population screening. By combining rational nanozyme design with a miniaturized and calibration-free sampling interface, this work provides a streamlined bioanalytical strategy with great potential for point-of-care testing in early disease diagnosis.

Surface-bubble-modulated liquid chromatography (SBMLC) is an aqueous liquid chromatography that has a hybrid stationary phase consisting of gas phase fixed in the pores of a hydrophobic packing material, in addition to the hydrophobic moiety of the material and aqueous mobile phase liquid/hydrophobe interface. Despite the proposition that the fixed gas phase may be utilized as a viable stationary phase for the separation of nonpolar gaseous compounds, such as permanent gases, it remains impractical to attain a satisfactory level of resolution due to the conspicuously low column separation efficiency. In this study, we have explored that the efficiency of an SBMLC column is diminished by high diffusivity of gaseous analytes in the stationary gas phase. However, it was found that the efficiency was remarkably enhanced by preventing contact between the gas phases in the porous particles through mix-packing the column with particles containing fixed gas phase together with those without gas phase. The findings demonstrate that nonporous octadecyl-bonded silica (ODS), pure silica, and large-pore ODS can be utilized as a mix-packing material in conjunction with porous ODS particles for the SBMLC separation of permanent gases. In this method, component gases can be separated by means of direct injection of a gas sample into the SBMLC column. Finally, the efficacy of this advanced SBMLC method is demonstrated by its ability to achieve an efficient separation of argon and oxygen, which is difficult to achieve by the conventional gas chromatographic method. SBMLC can offer unique selectivity for the separation of nonpolar gases without interference from coexisting gaseous components such as water and carbon dioxide.

Cervical cancer is one of the diseases that threaten women's health. Early screening and assessment are crucial for disease intervention and treatment. However, existing diagnostic technologies generally have problems such as invasive, high cost, and complex operation, which limit their widespread application in clinical early screening. Therefore, there is an urgent need to develop a rapid, low-cost, minimally invasive, and highly sensitive method for cervical cancer assessment. Protein phosphorylation levels show specific dynamic changes at different stages of cervical cancer development. Herein, we report a phosphoprotein identification method based on a stretchable photonic crystal. Three fluorescent probes were loaded onto the stretchable photonic crystal that constructed a cross-response sensor. The photonic bandgap was dynamically regulated by mechanical stretching to match with the emission wavelengths of the multiple probes, thereby enhancing fluorescence and amplifying signal differences. Without the need for additional probe synthesis and labeling, our strategy can accurately pinpoint the stage of cervical cancer development based on serum samples, with an accuracy rate of up to 94%. This study provides a simple, efficient, and clinically promising detection method for the assessment of cervical cancer.

Developing single sensors capable of sensing multiple volatile organic compounds (VOCs) by quantitative fluorescence (QF) is highly desirable and is required to cover distinct analytes across different concentration levels. Current multi-VOC sensors based on polymers or oligomers suffer from two major drawbacks, whereas the exploitation of ideal multi-VOC sensors based on small molecules is still challenging. In this work, three donor-carborane-acceptor sensors (Cb-FL/Cb-NE/Cb-NA) with aggregation-induced emission and through-space charge transfer (TSCT) potential were developed. These sensors were assembled in centrosymmetric dimers in the crystals and in consistent aggregates in the films. In the sensing of trace VOCs, the film-based Cb-FL and Cb-NE showed a particular emission-off response to amines, while Cb-NA showed an evident emission-off response (>1% at 2 g/m³) to seven distinct analytes, including toluene, diethyl sulfide, dipropylamine, with the QF sensitivity maintained in 3 orders of magnitude in concentration (178 mg/m³-88.93 g/m³ at most) and good discrimination of homologous VOCs under a fixed concentration. Moreover, fast response/recovery in 16-60/8-15 s and low detection limits of 178-209 mg/m³ were achieved in the multi-VOC sensing by Cb-NA. Theoretical modelings showed that Cb-NA harvested TSCT in single molecules dissociated from the consistent dimers and proceeded with independent emission quenching, together leading to the long-range QF sensitivity toward multiple VOCs.

Sensitive, rapid, and multiplexed detection of foodborne pathogens is critical for ensuring food safety, given the prevalence of multipathogen contamination in foods. Herein, we developed a polystyrene (PS) microsphere-enabled three-dimensional (color/size/number) sensing strategy and further established an oil-immersion microscopy and computer vision-integrated imaging biosensor for multiplexed detection of foodborne pathogens. This method employed differentially colored and sized microspheres as signal probes for pathogen encoding. By the integration of aptamer-binding reactions with the computer vision algorithm-based decode and counting process, the number of PS probes was correlated with the corresponding pathogen concentration. Meanwhile, the oil-immersion imaging system significantly enhanced microsphere image clarity and resolution, reducing method dependence on algorithmic and instrumental performance while improving applicability. This biosensor enables the simultaneous detection of multiple foodborne pathogens (e.g., Salmonella, Listeria monocytogenes, and Staphylococcus aureus) within 50 min at detection limits below 100 CFU/mL without DNA extraction, providing an intelligent platform for food safety assurance.

Isolating submicron and nanoparticles in microfluidics is challenging due to weak separation forces and dominance of diffusion at the nanoscale. While the unfavorable scaling of the separation forces can be addressed by nanofluidic systems, the operation of such systems faces several limitations such as low throughput, high pressure requirements, and clogging. To overcome these issues, we present electro-viscoelastic particle separation─a method combining electrophoretic slip-induced lift with viscoelastic microfluidics to enhance lateral forces on nanoparticles. Using a standard microchannel (60 μm height, 20 μm width, and 3 cm length), we demonstrated fractionation of a mixture of submicron polystyrene particles with different sizes in a viscoelastic medium under an applied electric field. This system improved the purity of 50, 200, and 500 nm particles by 39%, 29%, and 50%, respectively. We further applied this technique to purify cancer cell-secreted extracellular vesicles (EVs) from background nanoscale contaminants such as soluble proteins, achieving a 22% increase in EV purity. Notably, our platform operates at blockage ratios as low as 0.002, which is a considerable improvement over its inertial and viscoelastic counterparts. These experimental findings highlight the potential of integrating electric fields with viscoelastic migration for effective nanoparticle separation. A comparison of our results with state-of-the-art theoretical models of electro-viscoelastic migration (EVM) suggests that the current understanding requires further advancement. Nevertheless, the enhanced electro-viscoelastic lift predicted by these models underscores the prospect of this technique for separation of bionanoparticles.

The ninhydrin assay is an interesting alternative for protein quantification to the widely used Kjeldahl and elemental analysis methods. The two latter methods only measure the nitrogen content that must be converted into the protein content using empirical factors. In contrast, the ninhydrin reaction is more selective and reacts with primary amines including α-amino acids but not with nitrate and nucleic acids, the main source of nonprotein nitrogen in biological samples. Here, we determined the protein contents of a number of samples with the Kjeldahl method and elemental analysis and measured the amount of liberated amino acids using the ninhydrin assay. These results allowed establishing a universal formula ω(P) = (AA - 0.21) × 11.2 for conversion of the amino acid content (AA, in mmol g^-1) into the protein content (ω(P) in % (w/w)) for solid samples. For liquid samples, the formula c(P) = (AAH - AA0) × 120 was established, where c(P) is the protein concentration in mg mL^-1 and AAH and AA0 are the measured amino acid equivalents in mmol mL^-1 with and without hydrolysis, respectively. The method showed good intraday and interday reproducibility and gave more accurate results than the Kjeldahl assay when applying the default conversion factor of 6.25.

The antidepressant citalopram, primarily known for its selective serotonin reuptake inhibitor properties, has attracted interest in the broader scope of its effects on cellular metabolism beyond the brain. This study explores metabolic alterations induced by citalopram in human colon cells, both normal and cancerous. Understanding the fate of citalopram in the colon environment is crucial for assessing its systemic and localized effects, particularly in the context of the colon-brain axis and metabolic reprogramming observed in cancer cells. We review the impact of citalopram on metabolic pathways, its transformation in colon cells, and differences between normal and cancerous cells in handling this compound. This study demonstrates that citalopram induces metabolic alterations in cancerous Caco-2 (G1), LoVo (G4), and normal CCD-18Co colon cells. Using Raman spectroscopy and imaging, distinct biochemical changes were identified in the endoplasmic reticulum and lipid droplets after treatment. These changes were reflected in Raman band intensity ratios 1080/1292 cm^-1, 1004/1660 cm^-1, and 1444/1266 cm^-1. Citalopram treatment led to altered lipid ratios (I_1444/1266) and increased nucleic acid (I_1080/1292) and protein (I_1004/1660) ratios, especially in cancerous cells, suggesting modulated lipogenesis, altered transcriptional activity, and endoplasmic reticulum stress-related protein changes. Raman spectroscopy proved to be a label-free method for monitoring drug-induced metabolic responses at the subcellular level. Citalopram also significantly reduced endoplasmic reticulum and lipid droplet areas in Caco-2 and LoVo cells, indicating disrupted cellular homeostasis and increased sensitivity to toxin-induced stress. In contrast, normal CCD-18Co fibroblasts showed increased lipid droplet accumulation, suggesting an adaptive detoxification response.