Wearable sweat analysis can extend health monitoring from clinics to daily life. However, sweat is produced slowly and at changing rates, which makes sweat handling difficult. During collection and transport, sweat may remain in the device, flow backward, mix with older sweat, or become contaminated. The liquid that reaches the sensor may therefore differ from freshly secreted sweat. Microfluidic valves can control when sweat moves, where it flows, and how it reaches the sensing region. This review compares five valve classes relevant to wearable sweat systems. They are capillary, Tesla, mechanical, stimuli-responsive, and electro-actuated valves. Each class is assessed in terms of its working principle, flow-control function, power requirement, reusability, suitable task, and practical limit. The comparison covers sweat retention, backflow control, time-separated collection, reagent isolation, and replacement of older sweat at the sensor. The reviewed studies are grouped by tested medium and setting, covering laboratory liquids, artificial sweat, collected human sweat, and direct on-body transport. The main unresolved problems are changing sweat rate, deformation during wear, limited reusability, and unstable materials or interfaces. Solving these problems is important for reliable valve operation during long-term wear.

Rapid identification of male-derived biological evidence enhances forensic casework efficiency, particularly in sexual assault investigations that require prioritization of male DNA for downstream short tandem repeat (STR) analysis. Here, we present an extraction-free direct loop-mediated isothermal amplification (LAMP) workflow targeting the Y-chromosomal sex-determining region Y (SRY) gene for male-specific DNA detection, with the autosomal human leukocyte antigen DRA (HLA-DRA) gene incorporated as a human-specific internal control. Three detection formats were systematically evaluated within a single extraction-free framework: colorimetric LAMP enabled visual SRY detection within 30 min at 65 °C; multiplex real-time LAMP simultaneously detected both SRY and HLA-DRA within 15 min, achieving limits of detection of 100 pg per reaction for male DNA and 10 pg per reaction for total human DNA; and an immunochromatographic strip (ICS)-based format provided instrument-free visual discrimination between male, female, and non-human samples through simultaneous dual-target readout on a single strip. To assess field applicability, five direct lysis reagents were evaluated for compatibility with each detection modality. Nuclease-free water preserved the pH conditions required for colorimetric detection, enabling reliable male DNA identification from whole blood diluted up to 1:25 and saliva diluted up to 1:5. NaOH-based lysis improved DNA release and amplification kinetics in real-time LAMP, enabling detection from blood diluted up to 1:125 and saliva diluted up to 1:625. A UDG/dUTP anti-contamination system was optimized for the ICS format to suppress carry-over-derived false-positive signals while maintaining robust visual band intensity-an essential requirement for reliable point-of-care interpretation. The optimized workflow was validated across multiple forensically relevant matrices including whole blood, saliva, swab-collected samples, and cigarette butt mock evidence, consistently discriminating male- from female-derived biological material. These results demonstrate that direct LAMP, when paired with appropriate lysis chemistry and detection modality, provides a rapid, sensitive, and operationally practical strategy for on-site male DNA screening and forensic evidence triage.

Rhodium is one of the most challenging platinum-group metals to recover by conventional solvent extraction owing to its kinetically inert coordination chemistry. In this study, the extraction of rhodium(III) from hydrochloric acid solutions into neat ionic liquids (ILs) was investigated, focusing on trioctylammonium chloride ([HTOA]Cl), a protic IL designed for anion extraction. To overcome the slow ligand substitution of rhodium(III), the effect of thermal pretreatment of the aqueous phase was examined. Heating a rhodium(III) solution in 8.0 mol dm[- 3] HCl at 100 °C for at least 2 h promoted chloro-complex formation. Subsequent dilution to 1.0 mol dm[- 3] HCl immediately before extraction minimized competitive inhibition by excess chloride ions, enabling efficient anion-exchange extraction. Under optimized conditions, a distribution ratio of 31.6 and an extraction percentage of 97% were achieved at an aqueous-to-IL volume ratio of 1:1. Among several ammonium- and imidazolium-based ILs examined, [HTOA]Cl exhibited the highest performance, demonstrating its suitability for rhodium(III) extraction from chloride media. ESI-MS analysis indicated the involvement of both mononuclear ([RhCl6][3-]) and dinuclear ([Rh2Cl8][2-] and [Rh2Cl9][3-]) chloro complexes, depending on the rhodium(III) concentration. Nearly quantitative back extraction was achieved using 12 mol dm[- 3] HCl. This method enabled selective rhodium recovery from multicomponent hydrochloric acid solutions and was successfully applied to a spent automotive catalyst leachate without requiring additional thermal pretreatment beyond the initial leaching process.

A simplified diffuse reflectance infrared Fourier transform (DRIFT) system using commercial silver powder was investigated as an alternative to previously reported silver colloid/filter-paper systems for infrared signal enhancement. Isonicotinamide, nicotinamide, and nicotinic acid were employed as model compounds to evaluate the spectral behaviour obtained using this simplified DRIFT system. Significant band-dependent enhancement was observed for isonicotinamide and nicotinamide when the samples were subjected to solvent-assisted mixing with silver powder followed by drying. In contrast, simple dry mixing with silver powder produced little or no enhancement, and the control compound nicotinic acid showed no comparable spectral changes. The enhanced spectra exhibited non-uniform increases in band intensity together with peak shifts, band splitting, and changes in spectral shape, suggesting that the observed spectral changes cannot be explained by simple physical mixing with silver powder. The simplified powder DRIFT system enabled observation over a broad spectral region without support-derived absorption and revealed band-dependent infrared enhancement together with peak shifts, band splitting, and spectral shape changes.

Coated-type composite chiral stationary phases (CSPs) based on homosubstituted (same substituents introduced onto the glucose unit) and heterosubstituted (different substituents grafted onto the glucose unit) amylose derivatives were prepared and their enantioseparation capabilities in high-performance liquid chromatography were evaluated. Investigations demonstrated that the enantioseparation capabilities of the composite CSPs generally fell in between those of the two single-component CSPs. Notably, several chiral analytes that failed to achieve resolution on the single-component CSPs were successfully discriminated on the composite ones, thereby extending the application scope of an individual amylose derivative-based CSP. Some anomalous retention and selectivity behaviors were also observed on the composite CSPs, which may be due to some interactions between the two polymers during cocoating. Additionally, the impact of mobile phase composition on enantioseparation was examined. In the hexane/2-propanol (80/20, 90/10, and 95/5, v/v) mobile phase system, a lower 2-propanol content in the mobile phase always results in higher retention factor k1, whereas the separation factor α does not change significantly, with the maximum variation of racemate 2 being approximatley 16%.

A sensitive electrochemical sensor for the detection of methotrexate (MTX), a widely used anticancer and anti‑autoimmune drug, was constructed. MTX monitoring is of great significance for reducing toxic side effects and guaranteeing clinical medication safety. The sensor was based on a glassy carbon electrode (GCE) modified with a nanocomposite of molybdenum disulfide (MoS2) nanosheets loaded with gold gold nanoflowers (AuNFs), followed by the electrochemical polymerization of alizarin red (AR) to form a stable polymeric film (PAR) on its surface. The MoS2 nanosheets were prepared via liquid-phase exfoliation, and the AuNPs were deposited onto them via electrodeposition. The morphology of the modified electrode (PAR/Au@MoS2/GCE) was characterized by scanning electron microscopy (SEM), and its electrochemical properties were investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The synergistic effect of the nanocomposite and the conductive polymer significantly enhanced the electrocatalytic activity towards MTX oxidation. Under optimized conditions, the oxidation peak current of MTX at the modified electrode was nearly six times higher than that at a bare GCE. The sensor exhibited a linear response to MTX concentrations ranging from 0.4 to 38.6 µM, with a low detection limit of 0.027µM (S/N = 3). The sensor demonstrated excellent reproducibility, stability, and selectivity. Its practical applicability was successfully validated by determining MTX content in commercial tablet formulations with satisfactory recoveries.

Accurate quantification of pesticide residues is critical to ensure the quality and safety of Rhizoma Polygonati, a well-recognized medicine-food homologous herb widely applied in functional food development. Strong matrix interference in gas chromatography-tandem mass spectrometry (GC-MS) detection and notable quantitative bias are frequently induced by the abundant pigments, polysaccharides, saponins and endogenous components in the herbal matrix. Conventional PSA and C18 adsorbents in standard QuEChERS protocols exhibit restricted purification capacity for this complex matrix, while most documented magnetic carbon-based adsorbents demand tedious pre-synthesis procedures that may block the active adsorption sites of nanomaterials. A modified QuEChERS-GC-MS method coupled with dynamic in-situ assembly strategy was established for 12 pesticide residues in Rhizoma Polygonati. Without pre-synthesis of any composites, in-situ functional synergy between NH2-SWCNTs and magnetic Fe3O4 nanoparticles was achieved during the dispersive solid-phase extraction (d-SPE) step. Superior purification performance to conventional adsorbents was obtained by this system, with the matrix effect range of target pesticides narrowed from -31.4%-64.3% to -25.3%-36.7%. Favorable linearity (R ≥ 0.9990), acceptable spiked recoveries (86.2%-106.5%) and stable precision (RSD ≤ 15.20%) were validated through systematic method validation, providing a feasible and robust analytical protocol for pesticide residue monitoring in Rhizoma Polygonati and other complex herbal matrices.

DNA adducts analysis is crucial for elucidating the mechanism of mutagenesis and carcinogenesis induced by various chemical compounds. Liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-MS/MS) is commonly employed to determine DNA adduct. Pretreatment is essential in DNA adduct analysis due to a significant concentration disparity between normal 2'-deoxynucleosides (dNs) and DNA adducts. The level of DNA adducts is typically assessed by the ratio of DNA adducts to normal 2'-deoxyguanosine (dG) when the DNA adducts originate from dG. Consequently, the determination of dG and DNA adducts is necessary for accurate evaluation. Reversed-phase (RP)-solid-phase extraction (SPE) is the first choice for pretreatment of DNA adducts analysis. This pretreatment using RP-SPE effectively enriches DNA adducts while removing a substantial amount of dNs, particularly thymidine (T) and 2'-deoxyadenosine (dA), which may suppress the ionization of DNA adducts in the electrospray ionization (ESI) process. However, two separate measurements are required to determine the concentrations of dG and DNA adducts, as dG is removed during the SPE process. Therefore, an SPE method that simultaneously extracts dG and DNA adducts is desirable. In this study, we investigated the applicability of hydrophilic interaction chromatography (HILIC)-type SPE sorbents developed by our team, for the pretreatment of DNA adduct analysis. N[2]-ethyl-2'-deoxyguanosine (EtdG), an acetaldehyde-derived DNA adduct, was selected as a model DNA adduct. By optimizing the washing and eluting solutions, dG and EtdG were simultaneously extracted from the sample solution while eliminating T and dA. This pretreatment method enables the simultaneous measurements of dG and DNA adducts concentration, thereby enhancing the accuracy and rapidity of the DNA adducts analysis.

Osteosarcoma is a highly aggressive bone malignancy requiring precise tools for early diagnosis and effective evaluation of chemotherapy efficacy. Here, we report an "off-on" fluorescent nanosensor based on nitrogen-doped carbon nanodots (N-CNDs) for the sensitive and selective detection of caspase-3 activity, a key apoptosis executor. The sensor is constructed by conjugating carboxyl-functionalized N-CNDs with a BHQ1-labeled peptide substrate containing the caspase-3-specific DEVD cleavage motif. In the absence of caspase-3, fluorescence is quenched via FRET. Upon caspase-3 activation, the peptide is cleaved, releasing BHQ1 and restoring fluorescence. The nanosensor exhibits high sensitivity (detection limit of 0.0106 U/mL), excellent selectivity, and robust performance in complex biological media. As a proof-of-concept application, it detects elevated caspase-3 activity in osteosarcoma cell lysates (MG-63) compared to normal osteoblast lysates (hFOB1.19) and enables quantitative, dose-dependent assessment of apoptosis induced by cisplatin and doxorubicin directly in cancer cell lysates. With its current format, this cell-lysate-based platform provides a practical and sensitive tool for preclinical drug screening and rapid comparison of chemotherapeutic potency, while laying a foundation for future adaptation toward live-cell and in vivo imaging applications.

This study reports the first development of gas chromatographic columns packed with activated carbon (AC)-coated adsorbent particles. The AC-coated adsorbent particles were prepared by coating an AC layer on solid support particles using a vacuum carbon coater. Glass beads, diatomite, a porous polymer, and activated alumina particles were investigated as the support materials. The AC layer was uniformly coated on the surface of each support material, achieving a thickness of approximately 300-400 nm after 500 coating cycles. The AC-coated particles were packed in a stainless steel tube with an inner diameter of 1.0 mm and a length of 1.0 m to prepare a packed capillary column. The retention performance of the AC-coated particle-packed columns was evaluated using a capillary gas chromatograph coupled with a flame ionization detector. Strong retention for typical low-molecular-weight organic compounds, including methane, ethane, and propane, was observed. The retention power increased with increasing number of AC-coating cycles and support surface area. The theoretical plate numbers were lower for adsorbents coated on nonporous and low-porous supports, and higher for supports with a large specific surface area. The results demonstrated that the present AC-coating method readily affords AC adsorbents with high retention for typical volatile compounds.

Condensed micelle solutions are ubiquitously seen and utilized in foods, medicine, oil recovery, and so on. It is well-known that micelles formed from ionic surfactants drastically change their aggregate morphologies from spherical to short, rigid rod-like, and occasionally to long, winding worm-like structures as the concentration of the co-existing salts is varied. In general, these large-scale morphological changes induced by additive salt have been directly assessed by X-ray or neutron scattering spectroscopies. However, industrial processes are often carried out under open-system and atmospheric conditions, thus they show transient and dynamic changes of their structures and resultant viscoelastic properties according to the environmental changes. Here we examined whether Raman scattering spectroscopy is applicable for detecting such large-scale morphological changes in micelles by monitoring the corresponding changes occurring in the local packing environment of neighboring surfactant alkyl chains. As a representative micelle-salt system, cetyltrimethylammonium bromide (CTAB) and sodium p-toluene sulfonate (NapTS) were studied by varying their concentration ratio. As a result, it was proposed that the CH2 twisting and scissoring modes were useful indices to discriminate the morphological changes in micelles. These results provide a useful index for monitoring the transient structural changes of micelle solutions and elucidating the mechanism of the resultant changes in viscoelastic properties in situ and on-site monitoring.

The development of new analytical tools remains a powerful approach in analytical chemistry, and three-dimensional (3D) printing has gained increasing popularity as a manufacturing technique in recent years. The fabrication of experimental tools using 3D printers has attracted attention in many fields. However, objects fabricated by fused filament fabrication (FFF) may contain gaps between printed paths, and which can cause leakage when liquid is introduced. In this study, solvent-based post-processing was performed in order to fill layer gaps in FFF-printed polypropylene fluidic chips. As methods, a compression process and solvent-based post-processing were applied. In the compression process, a polypropylene fluidic chip was compressed using a compression tool while being heated. After this compression process, solvent-based post-processing was conducted. The post-processed chip was used to measure peak profile during flow-injection measurement. As a result, peak profiles were obtained, and no leakage from the chip was observed during the measurements.

A novel and highly sensitive electrochemical sensor based on an electropolymerized bromocresol green (BCG) film-modified pencil graphite electrode (poly(BCG)@PGE) was developed for the determination of tinidazole (TNDZ). The electropolymerization of BCG on the electrode surface significantly enhanced the electrochemical response toward TNDZ by improving electron-transfer kinetics and increasing the effective surface area. The fabrication and surface characteristics of the modified electrode were systematically investigated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier-transform infrared spectroscopy (FT-IR). The electrochemical behavior of TNDZ was studied using CV and differential pulse voltammetry (DPV). Key experimental parameters affecting sensor performance, including the pH of the electrolyte solution, monomer concentration, and number of electropolymerization cycles, were optimized. Under the optimized conditions, the proposed sensor exhibited a wide linear dynamic range (LDR) from 0.4 to 500 µM for TNDZ determination, with a high sensitivity of 1402 µA·mM[-1]·cm[-2] and a low limit of detection (LOD) of 0.11 µM. The practical applicability of the developed voltammetric sensor was successfully demonstrated by the determination of TNDZ in artificial blood, pharmaceutical formulation, and spring water samples. The obtained results showed satisfactory recoveries with high precision and accuracy, confirming the reliability and potential applicability of the poly(BCG)@PGE sensor for sensitive electrochemical monitoring of TNDZ in complex matrices.

Surface-enhanced laser-induced breakdown spectroscopy (SELIBS) using porous silicon (Si) is an attractive technique for liquid analysis in terms of requiring only microvolume samples, simple pretreatment, and a low plasma generation threshold. These features make SELIBS particularly suitable for industrial process monitoring, such as wet metal recovery processes. In our previous studies, we have analyzed sample solutions with volumes of approximately 10 µL by accumulating multiple spectra measured over the spread area of the sample. Reducing the volume of sample solutions and enabling rapid analysis remain important challenges for practical applications. In this study, we demonstrate single-shot analysis of trace gold (Au) in sub-microliter solution samples by SELIBS using porous Si, representing a step toward practical use. The emission line of Au was successfully observed using only 0.5 µL of sample and a single laser shot with an energy of 2.0 mJ. A calibration curve for Au was built using the Au intensity normalized by the Si intensity in the Au concentration range of 0.5-5.0 ppm (mg/L). From this calibration curve, a coefficient of determination of 0.997 was obtained. The limit of detection was estimated to be 0.48 ppm based on the Au intensity. The relative errors of predicted Au concentrations in additionally analyzed samples using the Au/Si calibration curve were approximately 10%. The proposed method has a potential for in-situ monitoring of wet metal recovery processes.