查看更多>>摘要：Currently used methods for in-field determination of illegal drugs involve various test kits based mainly on the immunoassay technique, where the presence of a compound of interest is assessed by antibody-antigen reaction and manifested by observable color change. Despite being accepted and widely used by police forces to test the presence of illegal drugs in a suspect person, these tests often suffer from unreliable results (high level of false -positive and/or false-negative) due to the cross-reactivity and difficulties with quantification. Therefore, we have developed a portable capillary electrophoresis instrument to determine illegal drugs in oral fluid collected from a suspected person. However, this drug analyzer has still required manual sample preparation. Therefore, this research aimed to develop, test, and validate a fully automated sample pretreatment (purification, extraction, pre-concentration) prototype compatible with the capillary electrophoresis drug of abuse analyzer and suitable for confirmatory analysis by mass spectrometry. The cotton swab from Salivette (R) oral fluid collector was examined and integrated into the fully automated extractor prototype. The recoveries for the automated extractor were between 18 and 20%, with repeatabilities within 5-11% for 3,4-methylenedioxymethamphet-amine (MDMA), 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxy-N-ethylamphetamine (MDEA), cocaine (COC), and cocaethylene (COET). The developed extraction device was easy to use even for unskilled persons, required minimal liquid handling, and was applicable to use in field conditions.
查看更多>>摘要：The extracellular microenvironments play a key role in tumor metabolism. To online dynamic monitoring the efficacy of 7-hydroxycoumarin (7-OHC) to cells cultured on microfluidics in acidic microenvironment, we developed an integrated multi-channel chip-mass spectrometry system. This system has six drug-loading units, cell culture chamber, metabolite collection, filtration, HPLC separation and MS detection. The cells in each microchannel will be incubated with continuous flow of culture medium, metabolites will be collected by the fixed card slot, automatic sampling needle will be precise positioned and sampled. Through this new system, the 7-hydroxycoumarin-sulfonate (7-OHC-sulfonate) and 7-hydroxycoumarin-glucuronide (7-OHC-glucuronide) can be determined in real-time. The results revealed that the addition of lactic acid promoted the formation of inactive 7-OHC-sulfonate and 7-OHC-glucuronide metabolites. Besides, acidic extracellular environment amplified cancer cell proliferation, indicating the anticancer effect of 7-OHC was weakened by low extracellular pH.
查看更多>>摘要：A rapid on-site determination of hydrogensulfite in food is of great importance for our health. Herein, a novel benzoindole-based fluorescent probe tethered with hydroxyl groups was synthesized. The probe displayed a good selectivity, fast response time (<68 s), and low determination limit (0.72 mu M) in solution. In order to prepare high performance test strips, various immobilization methods of probes onto paper substrates were investigated, including physical absorption of probe onto filter paper (test strip-1) and chemical immobilization of probe onto BP-PAA-attached paper (test strip-2) or probe-attached BP-PAA onto paper (test strip-3). Results showed that the determination limit of test strip-2 was 9 mu M, which was lower than that of test strip-1 (55 mu M) and test strip-3 (104 mu M). This phenomenon could be due to the deposition of most probes on the paper surfaces in the test strip-2 instead of the whole 3D paper structure (test strip-1) or the upper half of paper (test strip-3), which facilitated their reaction with hydrogensulfite. In particular, the test strip-2 could rapidly determine the amount of bisulfide in white-rot fungus, shiitake mushroom, and dried shrimp with good recoveries (91.8-104.1%), indicating the great application prospect of our proposed fluorescent test strip.
Yadav, Amit K.Gulati, PayalThakkar, AlokSolanki, Pratima R....
13页
查看更多>>摘要：SP17 is a mammalian protein found in the testis and spermatozoa that have been identified as a tumor-associated antigen in a range of human cancers. A unique method for fabricating the first ultrasensitive, selective, and labelfree immunosensor for the detection of SP17, a new cancer biomarker in complicated serum samples, is presented in this paper. This immunosensor was also the first biosensor built using a disposable ITO sheet modified with an aminosilane known as APTMS as an immobilization platform for fabricating the SP17 biosensor. The immobilization of chemical and biological species onto the electrode surface was cross-verified by various analytical and morphological techniques. Stepwise modifications done on the immunoelectrodes were also studied using electrochemical techniques. Selective interaction between anti-SP17 and SP17 with varying concentrations (100-5000 pg mL-1) was measured with the DPV technique. The immunosensor exhibited low LOD and LOQ of 70.07 and 233.57 pg mL-1, respectively, with a sensitivity of 0.013 mu A mL pg-1 cm-2. The fabricated immunosensor performance was analyzed by quantifying the SP17 concentrations in patient serum samples. The data obtained from the developed immunosensor demonstrated excellent reproducibility, repeatability, and selectivity among various interferants, including cancer biomarkers. Further, the observed results have been validated via ELISA, which showed good agreement with the electrochemical results. This could establish a new platform for detecting other cancer biomarkers and can be employed for clinical diagnostics applications.
查看更多>>摘要：As one of the initiating DNA glycosylases in the base excision repair pathway, Uracil-DNA glycosylase (UDG) plays a pivotal role in maintaining genomic integrity. The abnormal expression of UDG in the organism is highly relevant to multiple diseases. Thus, rapid and sensitive detection of UDG activity is essential to aid early clinical diagnosis and biomedical research. Here we developed a rapid, sensitive and selective biosensor for UDG activity detection based on the substrate preference of Lambda exonuclease (lambda exo). The protruding end in the substrate produced by UDG could be digested at a markedly high rate by lambda exo, generating a detectable fluorescence signal. This proposed strategy for UDG detection exhibited high selectivity and high sensitivity (0.0001 U/mL) in a short time. It has also been successfully applied to detect UDG in real biological samples and the screening of UDG inhibitors.
de Andrade, Flavio M.Sales, Rafaellada Silva, Neirivaldo C.Pimentel, Maria Fernanda...
8页
查看更多>>摘要：This work describes the use of virtual standards as calibration samples in an innovative multivariate calibration approach for the on-line monitoring of alkyl-esters content during biodiesel production process using a miniature near infrared (NIR) spectrometer. For comparison purposes, a partial least squares (PLS) model was built using synthetic blends prepared in laboratory with different concentrations of oil, glycerol, biodiesel, and ethanol and resulted in a satisfactory predictive ability (root mean square error of prediction, RMSEP, of 1.51% w/w). When compared to conventional methods, calibration with synthetic blends has the advantage of simplifying the experimental procedure and reducing the need for reference analysis. Nevertheless, it still requires the preparation of a considerable number of blends in laboratory. To overcome this limitation, this study proposed an innovative approach where a PLS model was constructed based on virtual standards: representative calibration spectra were created by mathematically mixing spectra from pure components and performing an adjustment using the Piecewise Direct Standardization (PDS) method. This significantly reduced the need for calibration synthetic blends and led to similar results (RMSEP of 1.75% w/w), compared to the previous approach. This work also demonstrates the use of the constructed models to predict the concentration profiles of alkyl-esters during the batch transesterification process.
查看更多>>摘要：Antibiotics are widely used for improving the living conditions of livestock. However, residual antibiotics present in animal products induce several human diseases. Therefore, a simple, rapid, and cost-effective system for detecting and monitoring the presence of antibiotics in foods is in great demand to alleviate safety concerns. In this study, a highly sensitive and selective aptameric electrochemical sensing platform was designed based on nanomaterial modification and DNA nanotechnology. Electrochemically reduced graphene oxide and gold nanoparticles were used to modify the working surface of a screen-printed electrode to enhance electrical conductivity and biocompatibility. The electrode surface was further modified with self-assembled tetrahedral DNA nanostructures (TDN) to improve the detection sensitivity. The TDN allowed controlling the nano-spacing of aptamers immobilized on the electrode surface and placing aptamers in a solution-phase-like detecting environment to improve the target-binding efficiency without signal amplification modules. Differential pulse voltammetry was employed to measure electrical signals in proportion to the amount of ampicillin, the target antibiotic, present in buffer and spiked milk samples. The designed aptasensor was able to detect and measure the target ampicillin in less than 30 min over a wide concentration range of 10 pM to 1 mM, with a limit of detection of 1 pM, which is 100 times better than when using the same sensing probe without TDN modification. The aptasensor was reusable by simply rinsing with deionized water, remained stable during 15-day storage, and yielded reproducible results.
查看更多>>摘要：In recent years, various types of nanomaterials and nanoparticles have been very popular, also in analytical chemistry for sensors preparation. Ion-selective electrodes with solid contact were constructed, in which a layer of nanoparticles of selected metal oxides (zinc, copper and iron oxides) obtained by pulsed laser liquid ablation (PLAL) was placed between the glassy carbon solid electrode material and the ion-selective membrane. The basic analytical parameters of the obtained sensors were determined using potentiometric methods. Additionally, the electrochemical impedance spectroscopy method (EIS) was also used to investigate the electrical properties of the sensors. The obtained results were compared for all types of electrodes, both modified and unmodified, in order to investigate the effect of the type of nanoparticles and the thickness of their layer used as solid contact. It was found that the addition of metal oxide nanoparticles improved the analytical parameters of the sensors, mainly the potential stability and electrical parameters. The best results were obtained for an electrode with an intermediate layer of zinc oxide nanoparticles. In this case, a slope of 56.07 mV/dec, a linearity range of 1 x 10(5) - 1 x 10(-1) mol L-1 and a limit of detection of 3.66 x 10(6) mol L-1 were obtained. Particularly noteworthy is the significant improvement in the stability of the potential of this electrode and the long life of more than 5 months.
查看更多>>摘要：Green-synthesized nanobiomaterials can be engineered as smart nanomedicine platforms for diagnostic and therapeutic purposes in medicine. Herein, we investigated the bioengineering of silver nanoparticles (AgNPs) and evaluated their physicochemical, antibacterial, biofilm inhibitory, anticoagulant, and antioxidant perfor-mance. Characterization of the AgNPs was performed utilizing UV-visible, transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD), dynamic light scattering (DLS), and Fourier transform infrared spectroscopy (FT-IR). The spherical shaped AgNPs were proven by TEM and SEM techniques. Moreover, the XRD diffraction patterns demonstrated that the nanoparticles were in a crystalline state. The DLS represented the hydrodynamic particle size of the NPs at 49.62 nm at a pH of 9. The calculated minimum inhibitory concentration (MIC) of AgNPs toward Staphylococcus aureus (ATCC 25923) was 8 mu g mL-1, which was almost similar to tetracycline by the value of 4 mu g mL-1. Moreover, the minimum bactericidal concentration (MBC) of AgNPs was 64 mu g mL-1, which was significantly less than the determined value of 256 mu g mL-1 for tetracycline. Considering the pathogenic and standard S. aureus, the evaluated concentrations of AgNPs and tetracycline showed significant biofilm inhibitory performance. Furthermore, the bioengineered AgNPs exhibited significant anticoagulant activity at 500 mu g mL(-1) compared to saline (P < 0.001). In addition, the biogenic AgNPs inhibited 69.73 +/- 0.56% of DPPH free radicals at 500 mu g mL(-1), indicating considerable antioxidant potential.
查看更多>>摘要：Accurate identification of mutant pathogens derived from genetic polymorphisms is highly desired in clinical diagnosis. However, current detection methods based on Watson-Crick hybridization suffers from false positives due to the cross-reactivity of wild-type sequences. In this study, we developed an accurate identification of mutant pathogens by combining programmable DNAzyme and target nucleic acid sequence-triggered tran-scription. Single nucleotide variants (SNVs) are the most plentiful type of mutations in the genome. High specificity to discriminate SNV was first achieved by rational design of dual-hairpin DNA structure and DNA-zyme's capability of site-specific cleavage. T7 RNA polymerase-mediated transcription amplification was introduced to exponentially increase the sensitivity by encompassing T7 promoter sequence into the dual-hairpin DNA structure. The design of this biosensor is fast and straightforward without many computational steps, and the highly sensitive biosensor can detect not only SNVs but also occasional insertions and large deletions in the genome. We showed that the assay could rapidly detect COVID-19 variant and methicillin-resistant Staphylo-coccus aureus (MRSA), and the limit of detection is 0.96 copy/mu L. The modular design of functional DNA enables this biosensor be easily reconfigured and is useful diagnosis of emerging infectious diseases caused by mutant pathogens.
NSTL
Elsevier