Displaying publications 41 - 60 of 336 in total

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  1. Commercial kitchenware glass as a potential thermoluminescent media for retrospective dosimetry
    Wahib NB, Khandaker MU, Aqilah Binti Mohamad Ramli N, Sani SFA, Bradley DA
    Appl Radiat Isot, 2019 Jun;148:218-224.
    PMID: 31003071 DOI: 10.1016/j.apradiso.2019.04.001
    Study has been made of the thermoluminescence (TL) yield of various glass-based commercial kitchenware (Reko-China, Skoja-France, Godis-China, Glass Tum-Malaysia, Lodrat-France). Interest focuses on their potential for retrospective dosimetry. Use was made of a60Co gamma-ray irradiator, delivering doses in the range 2-10 Gy. Results for the various media show all the glassware brands to yield linearity of response against dose, with a lower limit of detection of ∼0.06 and ∼0.08 Gy for loose and compact powdered samples. Among all of the brands under study, the Lodrat glassware provides the greatest sensitivity, at 6.0 E+02 nC g-1 Gy-1 and 1.5E+03 nC g-1 Gy-1 for compact- and loose-powdered forms respectively. This is sufficiently sensitive to allow its use as a TL material for accident dosimetry (2 Gy being the threshold dose for the onset of a number of deterministic biological effects, including skin erythema and sterility). Energy Dispersive X-ray (EDX) analyses have been conducted, showing the presence of a number of impurities (including C, O, Na, Mg, Al, Si, Ca and Br). Fading of the irradiated glasses show the amount of better than 3% and 5% of the stored energy for both loose and compact powdered samples within 9 days post irradiation. As such, commercial kitchenware glass has the potential to act as relatively good TL material for gamma radiation dosimetry at accident levels. This is the first endeavour reporting the TL properties of low cost commercial kitchenware glasses for gamma-ray doses in the few Gy range, literature existing for doses from 8 Gy to 200 Gy.
    Matched MeSH terms: Limit of Detection
  2. UPLC method for the determination of vitamin E homologues and derivatives in vegetable oils, margarines and supplement capsules using pentafluorophenyl column
    Wong YF, Makahleh A, Saad B, Ibrahim MN, Rahim AA, Brosse N
    Talanta, 2014 Dec;130:299-306.
    PMID: 25159413 DOI: 10.1016/j.talanta.2014.07.021
    A sensitive and rapid reversed-phase ultra performance liquid chromatographic (UPLC) method for the simultaneous determination of tocopherols (α-, β-, γ-, δ-), tocotrienols (α-, β-, γ-, δ-), α-tocopherol acetate and α-tocopherol nicotinate is described. The separation was achieved using a Kinetex pentafluorophenyl (PFP) column (150 × 2.1mm, 2.6 µm) with both photodiode array (PDA) and fluorescence (FL) detectors that were connected in series. Column was thermostated at 42°C. Under a gradient system consisting of methanol and water at a constant flow rate of 0.38 mL min(-1), all the ten analytes were well separated in less than 9.5 min. The method was validated in terms of linearity, limits of detection and quantitation, precision and recoveries. Calibration curves of the ten compounds were well correlated (r(2)>0.999) within the range of 100 to 25,000 μg L(-1) for α-tocopherol acetate and α-tocopherol nicotinate, 10 to 25,000 μg L(-1) for α-tocotrienol and 5 to 25,000 μg L(-1) for the other components. The method is simple and sensitive with detection limits (S/N, 3) of 1.0 to 3.0 μg L(-1) (FL detection) and 30 to 74 μg L(-1) (PDA detection). Relative standard deviations for intra- and inter-day retention times (<1%) and peak areas (≤ 4%) were obtained. The method was successfully applied to the determination of vitamin E in vegetable oils (extra virgin olive, virgin olive, pomace olive, blended virgin and refined olive, sunflower, soybean, palm olein, carotino, crude palm, walnut, rice bran and grape seed), margarines and supplements.
    Matched MeSH terms: Limit of Detection
  3. Fulltext Development of High Resolution Melting Analysis for the Diagnosis of Human Malaria
    Chua KH, Lim SC, Ng CC, Lee PC, Lim YA, Lau TP, et al.
    Sci Rep, 2015;5:15671.
    PMID: 26507008 DOI: 10.1038/srep15671
    Molecular detection has overcome limitations of microscopic examination by providing greater sensitivity and specificity in Plasmodium species detection. The objective of the present study was to develop a quantitative real-time polymerase chain reaction coupled with high-resolution melting (qRT-PCR-HRM) assay for rapid, accurate and simultaneous detection of all five human Plasmodium spp. A pair of primers targeted the 18S SSU rRNA gene of the Plasmodium spp. was designed for qRT-PCR-HRM assay development. Analytical sensitivity and specificity of the assay were evaluated. Samples collected from 229 malaria suspected patients recruited from Sabah, Malaysia were screened using the assay and results were compared with data obtained using PlasmoNex(TM), a hexaplex PCR system. The qRT-PCR-HRM assay was able to detect and discriminate the five Plasmodium spp. with lowest detection limits of 1-100 copy numbers without nonspecific amplifications. The detection of Plasmodium spp. in clinical samples using this assay also achieved 100% concordance with that obtained using PlasmoNex(TM). This indicated that the diagnostic sensitivity and specificity of this assay in Plasmodium spp. detection is comparable with those of PlasmoNex(TM). The qRT-PCR-HRM assay is simple, produces results in two hours and enables high-throughput screening. Thus, it is an alternative method for rapid and accurate malaria diagnosis.
    Matched MeSH terms: Limit of Detection
  4. Development of a dry-reagent-based nucleic acid-sensing platform by coupling thermostabilised LATE-PCR assay to an oligonucleotide-modified lateral flow biosensor
    Ang GY, Yu CY, Chan KG, Singh KK, Chan Yean Y
    J Microbiol Methods, 2015 Nov;118:99-105.
    PMID: 26342435 DOI: 10.1016/j.mimet.2015.08.024
    In this study, we report for the first time the development of a dry-reagent-based nucleic acid-sensing platform by combining a thermostabilised linear-after-the-exponential (LATE)-PCR assay with a one-step, hybridisation-based nucleic acid lateral flow biosensor. The nucleic acid-sensing platform was designed to overcome the need for stringent temperature control during transportation or storage of reagents and reduces the dependency on skilled personnel by decreasing the overall assay complexity and hands-on time. The platform was developed using toxigenic Vibrio cholerae as the model organism due to the bacterium's propensity to cause epidemic and pandemic cholera. The biosensor generates result which can be visualised with the naked eyes and the limit of detection was found to be 1pg of pure genomic DNA and 10CFU/ml of toxigenic V. cholerae. The dry-reagent-based nucleic acid-sensing platform was challenged with 95 toxigenic V. cholerae, 7 non-toxigenic V. cholerae and 66 other bacterial strains in spiked stool sample and complete agreement was observed when the results were compared to that of monosialoganglioside (GM1)-ELISA. Heat-stability of the thermostabilised LATE-PCR reaction mixes at different storage temperatures (4-56°C) was investigated for up to 90days. The dry-reagent-based genosensing platform with ready-to-use assay components provides an alternative method for sequence-specific detection of nucleic acid without any cold chain restriction that is associated with conventional molecular amplification techniques.
    Matched MeSH terms: Limit of Detection
  5. Maternal and infant vitamin B12 status during infancy predict linear growth at 5 years
    Strand TA, Ulak M, Kvestad I, Henjum S, Ulvik A, Shrestha M, et al.
    Pediatr Res, 2018 11;84(5):611-618.
    PMID: 29967525 DOI: 10.1038/s41390-018-0072-2
    BACKGROUND: Many children worldwide have poor vitamin B12 status. The objective of this study was to estimate association between maternal and infant vitamin B12 status and long-term growth.

    METHODS: We randomly selected 500 Nepali mother-infant pairs and measured maternal intake and infant and maternal vitamin B12 status using plasma cobalamin, total plasma homocysteine, and methylmalonic acid concentrations. We revisited available children when they were 5 years old and measured growth. The associations between intake and maternal and infant markers of vitamin B12 and growth were estimated in multiple linear regression models adjusting for relevant confounders (n = 331).

    RESULTS: Maternal vitamin B12 intake and status and vitamin B12 status in infancy predicted linear growth at 5 years of age, but not during infancy. Each microgram increase in the vitamin B12 intake of the mother during infancy was associated with an increase in height of 0.4 (0.2, 0.6) height-for-age z-scores and 1.7 (0.7, 2.7) cm around the child's fifth birthday.

    CONCLUSION: Vitamin B12 status and intake in early life is an important determinant for linear growth at school age. Our findings should be verified in randomized, placebo controlled trials before translated into public health recommendations.

    Matched MeSH terms: Limit of Detection
  6. Determination of minimal sequence for zearalenone aptamer by computational docking and application on an indirect competitive electrochemical aptasensor
    Azri FA, Selamat J, Sukor R, Yusof NA, Raston NHA, Eissa S, et al.
    Anal Bioanal Chem, 2021 Jun;413(15):3861-3872.
    PMID: 34021369 DOI: 10.1007/s00216-021-03336-1
    Aptamers are short single-stranded oligonucleotides (either DNA or RNA) that can fold into well-defined three-dimensional (3D) spatial structures which enable them to capture their specific target by complementary shape interactions. Aptamers are selected from large random libraries through the SELEX process and only a small fraction of the sequence is involved in direct docking with the target. In this paper, we describe the possible truncation variants of zearalenone (ZEA) aptamer which might be an effective binding region for the target. The originally selected zearalenone (ZEA) aptamer was 80-mer in length and shown to bind the target with a high affinity (Kd = 41 ± 5 nM). Herein, computational docking simulation was performed with 15 truncated variants to determine the predicted binding energy and responsible binding site of the aptamer-analyte complex. The results revealed that 5 truncated variants had binding energy lower than - 7.0 kcal/mol. Circular dichroism analysis was performed on the shortlisted aptamer and the conformational change of aptamers was observed with the presence of an analyte. Aptamer Z3IN (29-mer) was chosen as the most enhanced affinity for its target with a dissociation constant of 11.77 ± 1.44 nM. The aptamer was further applied in the electrochemical aptasensor of ZEA based on an indirect competitive format. The results demonstrated that the truncated aptamer leads to an enhancement of the sensitivity of the biosensor.
    Matched MeSH terms: Limit of Detection
  7. Facile hydrothermal growth graphene/ZnO nanocomposite for development of enhanced biosensor
    Low SS, Tan MT, Loh HS, Khiew PS, Chiu WS
    Anal Chim Acta, 2016 Jan 15;903:131-41.
    PMID: 26709306 DOI: 10.1016/j.aca.2015.11.006
    Graphene/zinc oxide nanocomposite was synthesised via a facile, green and efficient approach consisted of novel liquid phase exfoliation and solvothermal growth for sensing application. Highly pristine graphene was synthesised through mild sonication treatment of graphite in a mixture of ethanol and water at an optimum ratio. The X-ray diffractometry (XRD) affirmed the hydrothermal growth of pure zinc oxide nanoparticles from zinc nitrate hexahydrate precursor. The as-prepared graphene/zinc oxide (G/ZnO) nanocomposite was characterised comprehensively to evaluate its morphology, crystallinity, composition and purity. All results clearly indicate that zinc oxide particles were homogenously distributed on graphene sheets, without any severe aggregation. The electrochemical performance of graphene/zinc oxide nanocomposite-modified screen-printed carbon electrode (SPCE) was evaluated using cyclic voltammetry (CV) and amperometry analysis. The resulting electrode exhibited excellent electrocatalytic activity towards the reduction of hydrogen peroxide (H2O2) in a linear range of 1-15 mM with a correlation coefficient of 0.9977. The sensitivity of the graphene/zinc oxide nanocomposite-modified hydrogen peroxide sensor was 3.2580 μAmM(-1) with a limit of detection of 7.4357 μM. An electrochemical DNA sensor platform was then fabricated for the detection of Avian Influenza H5 gene based on graphene/zinc oxide nanocomposite. The results obtained from amperometry study indicate that the graphene/zinc oxide nanocomposite-enhanced electrochemical DNA biosensor is significantly more sensitive (P 
    Matched MeSH terms: Limit of Detection
  8. Modified silver staining in 2DE improves protein detection even at extremely low sample concentration
    Liew YK, Neela V, Hamat RA, Nordin SA, Chong PP
    Electrophoresis, 2013 Feb;34(3):397-400.
    PMID: 23161123 DOI: 10.1002/elps.201200380
    The typical concentration of protein loaded varies from 0.13 to 1.40 μg/μL for a classical silver staining method in 2DE gel. Here, we present a simple modified classical silver staining method by modifying the silver impregnation and development reaction steps. This modified method detects the protein spots at extremely low loaded concentrations, ranging from 0.0048 to 0.0480 μg/μL. We recommend this modified silver staining as an excellent method for the limited biological samples used for silver-stained 2DE analysis. Altogether, the protocol takes close to two days from first dimension separation to second dimension separation, followed by silver staining, scanning, and analysis.
    Matched MeSH terms: Limit of Detection
  9. Improved peroxide biosensor based on Horseradish Peroxidase/Carbon Nanotube on a thiol-modified gold electrode
    Kafi AKM, Naqshabandi M, Yusoff MM, Crossley MJ
    Enzyme Microb Technol, 2018 Jun;113:67-74.
    PMID: 29602389 DOI: 10.1016/j.enzmictec.2017.11.006
    A new 3-dimensional (3D) network of crosslinked Horseradish Peroxidase/Carbon Nanotube (HRP/CNT) on a thiol-modified Au surface has been described in order to build up the effective electrical wiring of the enzyme units with the electrode. The synthesized 3D HRP/CNT network has been characterized with cyclic voltammetry and amperometry which results the establishment of direct electron transfer between the redox active unit of HRP and the Au surface. Electrochemical measurements reveal that the high biological activity and stability is exhibited by the immobilized HRP and a quasi-reversible redox peak of the redox centre of HRP was observed at about -0.355 and -0.275V vs. Ag/AgCl. The electron transfer rate constant, KSand electron transfer co-efficient α were found as 0.57s-1and 0.42, respectively. Excellent electrocatalytic activity for the reduction of H2O2was exhibited by the developed biosensor. The proposed biosensor modified with HRP/CNT 3D network displays a broader linear range and a lower detection limit for H2O2determination. The linear range is from 1.0×10-7to 1.2×10-4M with a detection limit of 2.2.0×10-8M at 3σ. The Michaelies-Menten constant Kapp M value is estimated to be 0.19mM. Moreover, this biosensor exhibits very high sensitivity, good reproducibility and long-time stability.
    Matched MeSH terms: Limit of Detection
  10. A red-shifted Bioluminescence Resonance Energy Transfer (BRET) biosensing system for rapid measurement of plasmin activity in human plasma
    Weihs F, Peh A, Dacres H
    Anal Chim Acta, 2020 Mar 15;1102:99-108.
    PMID: 32044001 DOI: 10.1016/j.aca.2019.12.044
    Proteases are key signalling molecules for many physiological processes and their dysregulation is implicated in the progression of a range of diseases. Sensitive methods to measure protease activities in complex biological samples are critical for rapid disease diagnoses. The proteolytic activity of plasmin reflects the fibrinolysis state of blood and its deregulation can indicate pathologies such as bleeding events. While Bioluminescence Resonance Energy Transfer (BRET) is a powerful and sensitive method for the detection of protease activity, the commonly applied blue-shifted BRET2 system, consisting of the Renilla luciferase Rluc2 and the large-stokes shift fluorescent protein GFP2, suffers from light absorption and light scattering in human plasma samples. To address this challenge, we developed a red-shifted BRET-based plasmin sensor by substituting BRET2 with the BRET6 system. BRET6 is composed of the red-shifted RLuc8.6 luciferase linked to the red light emitting fluorescent protein TurboFP635. The BRET6 biosensor exhibited 3-fold less light absorption in plasma samples compared to the BRET2 sensor leading to an up to a 5-fold increase in sensitivity for plasmin detection in plasma. The limits of detection for plasmin were determined to be 11.90 nM in 7.5% (v/v) plasma with a 10 min assay which enables biologically relevant plasmin activities of thrombolytic therapies to be detected. While a colorigenic plasmin activity assay achieved a similar detection limit of 10.91 nM in 7.5% (v/v) human plasma, it required a 2 h incubation period. The BRET6 sensor described here is faster and more specific than the colorigenic assay as it did not respond to unspiked human plasma samples.
    Matched MeSH terms: Limit of Detection
  11. A novel silver nanoparticles-based sensing probe for the detection of Japanese encephalitis virus antigen
    Lih Shan Lim, Suk Fun Chin, Suh Cem Pang, Magdline Sia Henry Sum, David Perera
    Sains Malaysiana, 2017;46:2447-2454.
    A novel silver nanoparticles (Ag NPs)-based optical sensing probe has been developed for the detection of Japanese Encephalitis virus (JEV). Ag NPs were initially deposited onto amine functionalized glass slides. Subsequently, JEV antibodies were self-assembled onto surfaces of Ag NPs to form optical sensing probes. The detection of JEV antigen was observed via changes in light absorbance by Ag NPs upon occurrence of JEV antigen-antibody bindings. A highly sensitive and rapid optical sensing probe for JEV antigen with a detection limit of 12.8 ng/mL (for S/N ratio = 3) and an analysis assay time of 1 h had been demonstrated.
    Matched MeSH terms: Limit of Detection
  12. An iron oxide nanoworm hybrid on an interdigitated microelectrode silica surface to detect abdominal aortic aneurysms
    Yan G, Li Q, Hong X, Gopinath SCB, Anbu P, Li C, et al.
    Mikrochim Acta, 2021 05 11;188(6):185.
    PMID: 33977395 DOI: 10.1007/s00604-021-04836-8
    An abdominal aortic aneurysm (AAA) is abnormal swelling in the abdominal aorta and a prevalent life-threatening disease. This research introduces a new interdigitated microelectrode (IDME)-sensing surface modified by iron oxide nanoworms (IONWs) for detecting the AAA biomarker insulin-like growth factor-1 (IGF1). A sandwich pattern was formulated with the IGF1 aptamer and IGFBP1 (IGF binding protein-1) on the IONW-constructed IDME hybrid to identify IGF1. The surface morphology of the IONWs revealed a uniform distribution of worm-like structures (80-100 nm) as confirmed by FESEM and FETEM analyses. Further, the presence of the major elements, Fe and O, was confirmed by EDX and XPS studies. The crystal planes that appeared in the IONW reflect cubic magnetite. IONW-modified IDME attained a limit of detection for IGF1 of 1 fM (3σ) with an aptamer-IGF1-IGFBP1 sandwich. This sandwich with IGFBP1 enhanced the current level at all concentrations of IGF1 and displayed linearity in the range 1 fM to 100 pM with a determination coefficient of R2 = 0.9373 [y = 3.38221x - 4.79]. Control experiments with complementary aptamer sequences, IGF2 and IGFBP3 did not show notable signal changes, indicating the specific detection of IGF1. This IONW constructed electrode helps to achieve the detection of low amounts of IGF1 and diagnose AAA at the stage prior to rupture.
    Matched MeSH terms: Limit of Detection
  13. Sol-gel hybrid methyltrimethoxysilane-tetraethoxysilane as a new dispersive solid-phase extraction material for acrylamide determination in food with direct gas chromatography-mass spectrometry analysis
    Omar MM, Wan Ibrahim WA, Elbashir AA
    Food Chem, 2014 Sep 1;158:302-9.
    PMID: 24731346 DOI: 10.1016/j.foodchem.2014.02.045
    A sol-gel hybrid sorbent, methyltrimethoxysilane-tetraethoxysilane (MTMOS-TEOS) was successfully used as new dispersive solid phase extraction (dSPE) sorbent material in the determination of acrylamide in several Sudanese foods and analysis using GC-MS. Several important dSPE parameters were optimised. Under the optimised conditions, excellent linearity (r(2)>0.9998) was achieved using matrix matched standard calibration in the concentration range 50-1000 μg kg(-1). The limits of detection (LOD) and limit of quantification ranged from 9.1 to 12.8 μg/kg and 27.8-38.9 μg/kg, respectively. The precision (RSD%) of the method was ⩽6.6% and recoveries of acrylamide obtained were in the range of 88-103%, (n=3). The LOD obtained is comparable with the LODs of primary secondary amine dSPE. The proposed MTMOS-TEOS dSPE method is direct and safe for acrylamide analysis, showed reliable method validation performances and good cleanup effects. It was successfully applied to the analysis of acrylamide in real food samples.
    Matched MeSH terms: Limit of Detection
  14. Assay and stability-indicating micellar electrokinetic chromatography method for the simultaneous determination of valacyclovir, acyclovir and their major impurity guanine in pharmaceutical formulations
    Al Azzam KM, Saad B, Makahleah A, Aboul-Enein HY, Elbashir AA
    Biomed Chromatogr, 2010 May;24(5):535-43.
    PMID: 19739243 DOI: 10.1002/bmc.1323
    A micellar electrokinetic chromatography (MEKC) method for the simultaneous determination of the antiviral drugs acyclovir and valacyclovir and their major impurity, guanine, was developed. The influences of several factors (surfactant and buffer concentration, pH, applied voltage, capillary temperature and injection time) were studied. Using tyramine hydrochloride as internal standard, the analytes were all separated in about 4 min. The separation was carried out in reversed polarity mode at 28 degrees C, 25 kV and using hydrodynamic injection (15 s). The separation was effected in a fused-silica capillary 100 microm x 56 cm and a background electrolyte of 20 mM citric acid-1 M Tris solution (pH 2.75), containing 125 mM sodium dodecyl sulphate and detection at 254 nm. The method was validated with respect to linearity, limit of detection and quantification, accuracy, precision and selectivity. Calibration curves were linear over the range 0.1-1 microg/mL (guanine) and from 0.1 to 120 microg/mL for both valacyclovir and acyclovir. The relative standard deviations of intra- and inter-day migration times and corrected peak areas were less than 5.0%. The proposed method was successfully applied to the determination of the analytes in tablets and creams. From the previous study it is concluded that the stability-indicating method developed for acyclovir and valacyclovir can be used for analysis of the drug in various stability samples.
    Matched MeSH terms: Limit of Detection
  15. Silver nanoparticles decorated polyaniline nanocomposite based electrochemical sensor for the determination of anticancer drug 5-fluorouracil
    Zahed FM, Hatamluyi B, Lorestani F, Es'haghi Z
    J Pharm Biomed Anal, 2018 Nov 30;161:12-19.
    PMID: 30142492 DOI: 10.1016/j.jpba.2018.08.004
    A highly efficient electrochemical sensor for the analysis of anticancer drug 5-fluorouracil (5-FU), is fabricated based on silver nanoparticles-polyaniline nanotube (AgNPs@PANINTs). AgNPs@PANINTs nanocomposite has been synthesized by a simple one-step method. Synthesized AgNPs@PANINTs nanocomposite was studied by Fourier transform infrared spectrometry, Scanning Electron Microscopy and Energy Dispersive X-ray. The fabricated PANINTs@AgNPs PGE was applied to the electrochemical sensing of 5-FU. Cyclic voltammetry and differential pulse voltammetry experiments illustrated high electro activity for the AgNPs@PANINTs nanocomposite. The study was explored using the Taguchi experimental design method. Electrochemical measurements using differential pulse voltammetry showed a wide linear relationship between 5-FU concentration and peak height within the range 1.0-300.0 μM with a low detection limit (0.06 μM). Also, the fabricated sensor showed excellent selectivity in the presence of two anticancer drugs and a number of other interfering compounds. The as-prepared sensor showed to be a promising device for a simple, rapid, and direct analysis of 5-FU.
    Matched MeSH terms: Limit of Detection
  16. Au/Pd@rGO nanocomposite decorated with poly (L-Cysteine) as a probe for simultaneous sensitive electrochemical determination of anticancer drugs, Ifosfamide and Etoposide
    Hatamluyi B, Lorestani F, Es'haghi Z
    Biosens Bioelectron, 2018 Nov 30;120:22-29.
    PMID: 30144642 DOI: 10.1016/j.bios.2018.08.008
    The simultaneous measurement of the concentration of anticancer drugs with a fast, sensitive and accurate method in biological samples is a challenge for better monitoring of drug therapy and better determine the pharmacokinetics. An electrochemical sensor was developed for the simultaneous determination of anticancer drugs, Ifosfamide (IFO) and Etoposide (ETO) based on pencil graphite electrode modified with Au/Pd@rGO nanocomposite decorated with poly (L-Cysteine). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were utilized to study the properties of the modified electrode. The electrochemical behavior of IFO and ETO on the Au/Pd@rGO@p(L-Cys) modified electrode was investigated by cyclic voltammetry and differential pulse voltammetry (DPV) techniques and the obtained results confirmed its efficiency for the individual and simultaneous sensing of IFO and ETO. After optimization of electrochemical parameters, the fabricated sensor presented excellent performance in simultaneous determination of IFO and ETO with a wide linear range from 0.10 to 90.0 μM and 0.01 to 40.0 μM and low detection limits (3 Sb/m) of 9.210 nM and 0.718 nM, respectively. In addition, this study proved that the constructed sensor could be useful to simultaneous analysis of IFO and ETO in biological samples and pharmaceutical compounds.
    Matched MeSH terms: Limit of Detection
  17. Molybdenum disulfide-gold nanoparticle nanocomposite in field-effect transistor back-gate for enhanced C-reactive protein detection
    Dalila NR, Arshad MKM, Gopinath SCB, Nuzaihan MNM, Fathil MFM
    Mikrochim Acta, 2020 10 05;187(11):588.
    PMID: 33015730 DOI: 10.1007/s00604-020-04562-7
    Nanofabricated gold nanoparticles (Au-NPs) on MoS2 nanosheets (Au-NPs/MoS2) in back-gated field-effect transistor (BG-FET) are presented, which acts as an efficient semiconductor device for detecting a low concentration of C-reactive protein (C-RP). The decorated nanomaterials lead to an enhanced electron conduction layer on a 100-μm-sized transducing channel. The sensing surface was characterized by Raman spectroscopy, ultraviolet-visible spectroscopy (UV-Vis), atomic force microscopy (AFM), scanning electron microscopy (SEM), and high-power microscopy (HPM). The BG-FET device exhibits an excellent limit of detection of 8.38 fg/mL and a sensitivity of 176 nA/g·mL-1. The current study with Au-NPs/MoS2 BG-FET displays a new potential biosensing technology; especially for integration into complementary metal oxide (CMOS) technology for hand-held future device application.
    Matched MeSH terms: Limit of Detection
  18. Fulltext Data on the optimisation and validation of a liquid chromatography-high-resolution mass spectrometry (LC-HRMS) to establish the presence of phosphodiesterase 5 (PDE5) inhibitors in instant coffee premixes
    Mohd Yusop AY, Xiao L, Fu S
    Data Brief, 2019 Aug;25:104234.
    PMID: 31384643 DOI: 10.1016/j.dib.2019.104234
    This paper presents the data on the optimisation and validation of a liquid chromatography-high-resolution mass spectrometry (LC-HRMS) to establish the presence of phosphodiesterase 5 (PDE5) inhibitors and their analogues as adulterants in instant coffee premixes. The method development data covered chromatographic optimisation for better analyte separation and isomeric resolution, mass spectrometry optimisation for high sensitivity and sample preparation optimisation for high extraction recovery (RE) and low matrix effect (ME). The validation data covered specificity, linearity, range, accuracy, limit of detection, limit of quantification, precisions, ME, and RE. The optimisation and validation data presented here is related to the article: "Determination of phosphodiesterase 5 (PDE5) inhibitors in instant coffee premixes using liquid chromatography-high-resolution mass spectrometry (LC-HRMS)" Mohd Yusop et al., 2019.
    Matched MeSH terms: Limit of Detection
  19. Determination of phosphodiesterase 5 (PDE5) inhibitors in instant coffee premixes using liquid chromatography-high-resolution mass spectrometry (LC-HRMS)
    Mohd Yusop AY, Xiao L, Fu S
    Talanta, 2019 Nov 01;204:36-43.
    PMID: 31357306 DOI: 10.1016/j.talanta.2019.05.078
    As a widely consumed beverage, coffee tends to be a target for intentional adulteration. This study describes the application of modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) coupled to liquid chromatography-high-resolution mass spectrometry (LC-HRMS) for simultaneous screening, identification, and quantification of undeclared phosphodiesterase 5 (PDE5) inhibitors in instant coffee premixes (ICPs). The mass spectrometer was operated in auto MS/MS acquisition for simultaneous MS and MS/MS experiments. Qualitative establishments from the suspected-target screening and targeted identification processes led to an unambiguous analyte assignment from the protonated molecule ([M+H]+) precursor ion which is subsequently used for quantification of 23 targeted PDE5 inhibitors. The analytical method validation covered specificity, linearity, range, accuracy, limit of detection (LOD), limit of quantification (LOQ), precisions, matrix effect (ME), and extraction recovery (RE). The specificity was established using the optimised chromatographic separation as well as the distinguishable [M+H]+ precursor ion. The linearity of each target analyte was demonstrated with a coefficient of determination (r2) of >0.9960 over the expected range of sample concentrations. The accuracy ranged from 88.1%-119.3% with LOD and LOQ of <70 ng/mL and 80 ng/mL, respectively. Excellent precisions were established within 0.4%-9.1% of the relative standard deviation. An insignificant ME within -5.2% to +8.7% was achieved using three different strategies of chromatography, sample extraction, and sample dilution. The RE was good for all target analytes within 84.7%-123.5% except for N-desethylacetildenafil at low (53.8%) and medium (65.1%) quality control levels. The method was successfully applied to 25 samples of ICPs where 17 of them were found to be adulterated with PDE5 inhibitors and their analogues. Further quantification revealed the total amount of these adulterants ranged from 2.77 to 121.64 mg per sachet.
    Matched MeSH terms: Limit of Detection
  20. Suspected-target and non-targeted screenings of phosphodiesterase 5 inhibitors in herbal remedies using liquid chromatography-quadrupole time-of-flight-mass spectrometry
    Mohd Yusop AY, Xiao L, Fu S
    Drug Test Anal, 2021 May;13(5):965-976.
    PMID: 32441056 DOI: 10.1002/dta.2861
    The lucrative market of herbal remedies spurs rampant adulteration, particularly with pharmaceutical drugs and their unapproved analogues. A comprehensive screening strategy is, therefore, warranted to detect these adulterants and, accordingly, to safeguard public health. This study uses the data-dependent acquisition of liquid chromatography-quadrupole time-of-flight-mass spectrometry (LC-QTOF-MS) to screen phosphodiesterase 5 (PDE5) inhibitors in herbal remedies using suspected-target and non-targeted strategies. For the suspected-target screening, we used a library comprising 95 PDE5 inhibitors. For the non-targeted screening, we adopted top-down and bottom-up approaches to flag novel PDE5 inhibitor analogues based on common fragmentation patterns. LC-QTOF-MS was optimised and validated for capsule and tablet dosage forms using 23 target analytes, selected to represent different groups of PDE5 inhibitors. The method exhibited excellent specificity and linearity with limit of detection and limit of quantification of <40 and 80 ng/mL, respectively. The accuracy ranged from 79.0% to 124.7% with a precision of <14.9% relative standard deviation. The modified, quick, easy, cheap, effective, rugged, and safe extraction provided insignificant matrix effect within -9.1%-8.0% and satisfactory extraction recovery of 71.5%-105.8%. These strategies were used to screen 52 herbal remedy samples that claimed to enhance male sexual performance. The suspected-target screening resulted in 33 positive samples, revealing 10 target analytes and 2 suspected analytes. Systematic MS and tandem MS interrogations using the non-targeted screening returned insignificant signals, indicating the absence of potentially novel analogues. The target analytes were quantified from 0.03 to 121.31 mg per dose of each sample. The proposed strategies ensure that all PDE5 inhibitors are comprehensively screened, providing a useful tool to curb the widespread adulteration of herbal remedies.
    Matched MeSH terms: Limit of Detection
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