Fluoride detection has been playing an important role in chemical, biological, and medicinal field, especially for keeping physical health and resisting environmental pollution. Herein, a urolithin B fluorescent probe has been successfully developed with good sensitivity, selectivity, anti-interference ability. The low limit of detection (LOD) refers to 0.156 μM, and the instant response time to F- is less than 1 s. The probe is suitable for quantitatively and qualitatively ratiometric detection for F- in solution with two distinct emission bands at 425 (blue) and 566 nm (orange), with the coordinate change of CIE from (0.38, 0.41) to (0.22, 0.11). Urolithin B displayed a remarkable ratiometric fluorescence response towards F-. The detection mechanistic was further proposed by NMR and electronic spectroscopic experiments combining with time-dependent density functional theoretical calculation.

Zeaxanthin is a naturally occurring xanthophyll carotenoid obtained from diet sources. Particularly, sweet corn is a major source of dietary zeaxanthin. To investigate the genetic basis of zeaxanthin content regulation in sweet corn, a recombinant inbred line (RIL) population comprising 191 families was constructed using two inbred lines (K44 and F22) with contrasting zeaxanthin content in the grain. The zeaxanthin content in the dry grains of this population grown at different locations was determined using high performance liquid chromatography (HPLC). Subsequently, 175 polymorphic simple sequence repeat (SSR) markers were used to construct a linkage map with a total length of 4322.37 cM and with an average distance of 24.4 cM. A total of eight QTLs located on chromosomes 4, 5, 7, 9, and 10 were detected. The QTLs located in umc1632-umc1401 on chromosome 7 were detected in different environments and explained 11.28-20.25% of the phenotypic variation, implying it is the main QTL controlling zeaxanthin content in the dry grains of sweet corn. Collectively, the present study provides a genetic map and theoretical guidance for the cultivation of sweet corn varieties with a high zeaxanthin content.

Inherent issues of subjectivity and inconsistency have long plagued immunohistochemistry (IHC)-based Her2 assessment, leading to the repeated issuance of guidelines by the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) for its standardization for breast cancer patients. Yet, all these efforts may prove insufficient with the advent of Trastuzumab deruxtecan (T-Dxd), a drug with the promise to expand to tumors traditionally defined as Her2 negative (Her2-). In this study, we attempted to address these issues by exploring an ELISA-like quantitative dot blot (QDB) method as an alternative to IHC. The QDB method has been used to measure multiple protein biomarkers including ER, PR, Ki67, and cyclin D1 in breast cancer specimens. Using an independent cohort (cohort 2) of breast cancer formalin-fixed paraffin-embedded (FFPE) specimens, we validated cutoffs developed in cohort 1 (Yu et al., Scientific Reports 2020 10:10502) with overall 100% specificity (95% CI: 100-100) and 97.56% sensitivity (95% CI: 92.68-100) in cohort 2 against standard practice with the dichotomized absolutely quantitated values. Using the limit of detection (LOD) of the QDB method as the putative cutoff point, tumors with no Her2 expression were identified with the number comparable to those of IHC 0. Our results support further evaluation of the QDB method as an alternative to IHC to meet the emerging need of identifying tumors with low Her2 expression (Her2-low) in daily clinical practice.

The quantification of intrahepatic covalently closed circular DNA (cccDNA) is important for assessing the efficiency of anti-HBV therapy. Exonuclease treatment is essential before real-time quantitative PCR (qPCR) or droplet digital PCR (ddPCR) measurement to improve the specificity of cccDNA quantification. In this research, we compared the limit of detection (LOD) of qPCR and ddPCR and evaluated the digestion efficiency of three exonuclease treatments, PSAD, exonuclease III and T5 exonuclease, when measuring cccDNA in cells or clinical samples by ddPCR. We demonstrated that the LOD of ddCPR was 5.9 copies/reaction, which was much lower than that of qPCR (54.9 copies/reaction), indicating that ddPCR is more sensitive than qPCR. Meanwhile, compared to PSAD or Exo III, UNG and T5 exonuclease treatment combined with ddPCR is more effective in detecting intrahepatic cccDNA in clinical samples. Finally, the median intrahepatic cccDNA was 2.6 copies/104 cells in 26 pairs of HCC samples determined by the improved ddPCR method. Therefore, we developed an optimized ddPCR method, which can be used for the absolute quantification of low levels of intrahepatic cccDNA more precisely.

The current report devised a novel isothermal diagnostic assay, termed as nanoparticle-based biosensor (NB)- and antarctic thermal sensitive uracil-DNA-glycosylase (ATSU)-supplemented polymerase spiral reaction (PSR; NB-ATSU-PSR). The technique merges enzymatic digestion of carryover contaminants and isothermal nucleic acid amplification technique (PSR) for simultaneous detection of nucleic acid sequences and elimination of carryover contamination. In particular, nucleic acid amplification and elimination of carryover contamination are conducted in a single pot and, thus, the use of a closed-tube reaction can remove undesired results due to carryover contamination. For demonstration purpose, Klebsiella pneumoniae is employed as the model to demonstrate the usability of NB-ATSU-PSR assay. The assay\'s sensitivity, specificity, and practical feasibility were successfully evaluated using the pure cultures and sputum samples. The amplification products were detectable from as little as 100 fg of genomic DNAs and from ~550 colony-forming unit (CFU) in 1 ml of spiked sputum samples. All K. pneumoniae strains examined were positive for NB-ATSU-PSR detection, and all non-K. pneumoniae strains tested were negative for the NB-ATSU-PSR technique. The whole process, including rapid template preparation (20 min), PSR amplification (60 min), ATSU treatment (5 min), and result reporting (within 2 min), can be finished within 90 min. As a proof-of-concept methodology, NB-ATSU-PSR technique can be reconfigured to detect various target nucleic acid sequences by redesigning the PSR primer set.

OBJECTIVE: To detect the pyrogen in CAR-T cells product employing the HL60-IL-6 assay.
METHODS: The HL60 cells were incubated with CAR-T cells injection or endotoxin standard for 48 hours. After then, the secreted cytokine interleukin-6 (IL-6) from HL60 cells was determined by ELISA. According to the four-parameter logistic curve fitted by Optical Density (OD) value corresponding to IL-6 and endotoxin standard concentration, the endotoxin equivalents of pyrogen content in the CAR-T cells products can be measured. Then, the method was validated, including the limit of detection (LOD), limit of quantitation, the recovery rate and the comparison of the determined results by HL60-IL-6 assay with that by the conventional pyrogen test, the Rabbit Pyrogen Test (RPT).
RESULTS: The HL60-IL-6 assay applied to pyrogen test in CAR-T cells products has been established and validated, The LOD was 0.03 EU/mL while the LOQ was 0.07 EU/mL, the recovery rates were 121.4% and 94.5% respectively. The results determined by HL60-IL-6 assay were consistent with that by the RPT.
CONCLUSIONS: The HL60-IL-6 assay can be employed in CAR-T cell products in vitro pyrogen test.

More and more severe energy problem triggers extensive application of nuclear energy, and the adverse effects brought by nuclear materials such as uranyl to the environment are becoming the concern, as it has become a threat to human\'s health. Therefore, the detection of uranyl is increasingly important, which aims to make the application of uranium under surveillance and protection. A lot of detection methods employing varying materials based on different techniques for uranyl have been proposed including those using expensive and complicated instruments such as ICP-MS, ESI-MS, and neutron activation analysis etc. Those methods based on expensive instruments often provide quite low limit of detection (LOD) and excellent validity and repeatability, however, methods that are low-cost, convenient and rapid are in demand because these are satisfied characters for on-site and in-time determination. In the review, we discuss uranyl sensors based on spectrographic techniques, which is facile and promising for rapid assessment of uranium content in practical application. Spectrographic techniques including fluorescence, UV-vis spectrophotometry, resonance light scattering (RLS) and surface enhanced Raman scattering (SERS) are evaluated. In detail, the core materials that playing extremely important roles in detection performance are stated consisting of small molecule, biomolecule, polymer and nanomaterial.

An innovative approach is presented for portable and sensitive detection of pathogenic bacteria. A novel synthetic hybrid nanocomposite encapsulating platinum nanoparticles, as a highly efficient catalyst, catalyzes the hydrolysis of the ammonia-borane complex to generate hydrogen gas. The nanocomposites are used as a label for immunoassays. A portable hand-held hydrogen detector combined with nanocomposite-induced signal conversion was applied for point-of-care testing of pathogenic bacteria. A hand-held hydrogen detector was used as the transducer. Escherichia coli O157:H7 (E. coli O157: H7), as detection target, formed a sandwich structure with magnetic beads and hybrid nanocomposites. Magnetic beads were used for separation of the sandwich structure, and hybrid nanocomposites as catalysts to catalyze the generation of hydrogen from ammonia-borane. The generated hydrogen was detected by a hydrogen detector using an electrochemical method. E. coli O157:H7 has a detection limit of 10 CFU·mL-1. The immunosensor made the hand-held hydrogen detector a point-of-care meter to be used outdoors for the detection and quantification of targets beyond hydrogen. Graphical abstract Schematic presentation of one-pot synthetic peptide-Cu3(PO4)2 hybrid nanocomposites embedded PtNPs (PPNs), encapsulating many Pt particles. The PPNs acts as an ideal immunoprobe for hand-held H2 detector signal readouts, by transforming pathogenic bacteria recognition events into H2 signals.

OBJECTIVE: Immuno-PCR (I-PCR), an ultrasensitive method, combines the versatility of ELISA with the exponential amplification capacity of PCR. Coupling of detection antibodies with the reporter DNA is a critical step of I-PCR. Gold nanoparticles (GNPs) and magnetic beads (MBs) are relatively easy to attach with the antibodies and DNA. Therefore, we designed MB-coupled GNP-based I-PCR (MB-GNP-I-PCR) assay for the detection of Mycobacterium tuberculosis antigen.
METHODS: GNPs were synthesized by chemical reduction and seed-mediated synthesis. Functionalized GNPs were prepared by coupling GNPs with the detection antibodies and reporter DNA and were characterized. Detection limit of M. tuberculosis-specific purified early secreted antigenic target-6 (ESAT-6) (Rv3875) was determined by MB-GNP-I-PCR.
RESULTS: Transmission electron microscopy revealed spherical and slightly polydispersed GNPs of ~20 and ~60 nm size. Coupling of antibodies to GNPs was indicated by a shift in absorption maxima from 524 to 534 nm, which was confirmed by transmission electron microscopy. A color reaction with ELISA and the presence of 76 bp product by PCR further validated the coupling of detection antibodies and signal DNA to the functionalized GNPs. Also, attachment of capture antibodies with MBs was confirmed by magneto-ELISA. Detection limit of purified ESAT-6 by MB-GNP-I-PCR was determined to be 10 fg/mL, 105-fold lower than analogous ELISA. Notably, no sample matrix effect was observed in the saliva samples of healthy individuals spiked with the purified ESAT-6.
CONCLUSIONS: Unlike conventional I-PCR (solid format), MB-GNP-I-PCR (liquid format) is relatively simple with the reduced background signals, which can be further exploited for the clinical diagnosis of tuberculosis.

This paper reports on the advanced development of an ultrasensitive method for the detection of benzene, toluene, and ethylbenzene (or BTE) by low-pressure photoionization mass spectrometry (LPPI-MS). The LPPI source is composed of a laboratory-assembled krypton lamp and a stainless steel cylindrical ionizer. A compact V-shaped mass spectrometer is coupled to the LPPI source with a set of ion immigration optics under dc bias. The fixed standard concentration (FSC) and fixed standard volume (FSV) method are employed to calibrate the sensitivities of the instrument. The corresponding detection sensitivity toward BTE is 4-7 counts/pptv and the 2σ limit of detection (LOD) is 0.5-0.8 part per trillion by volume (pptv). In addition, the measurement accuracy is 95%-105%, and the corresponding precision ranges from 3% to 15% and from 9% to 31% for the FSC and FSV methods, respectively. The stability (standard deviation) of LPPI-MS for a 1 ppbv BTE mixture is less than 0.025 (>12 h). In the detection of BTE, water in ambient air is the most significant interfering factor, leading to the increased background, and inferior LODs of 1-2 pptv for BTE under an RH of ∼90% is observed. Experimental results indicated that LPPI-MS is reliable for the detection of sub-pptv levels of BTE under laboratory conditions.