Displaying publications 1 - 20 of 37 in total

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  1. Chang L, Liu X, Lee CY, Zhang W
    Anal Chim Acta, 2023 Oct 23;1279:341825.
    PMID: 37827623 DOI: 10.1016/j.aca.2023.341825
    Triphenyltin is an estrogen like pollutant that poses significant environmental threats due to its highly accumulative toxicity. To improve regulation, a fast and sensitive detection method is urgently needed. SERS can capture fingerprint information and is capable of trace detection, making it an ideal solution. Here, we present a sprayed substrate comprised of lightconfining structures and gold nanorod assemblies that are easy to prepare, low-cost, and can form dense hotspots under confined evaporation. The substrates are three-layered: initially, a gold nanorod layer is sprayed as a support, then sputter Ag film on the surface to form a lightconfining structure, followed by another gold nanorod layer sprayed on the Ag film. The coupling of nanorod assembly with lightconfining Ag films leads to 10-fold sensitivity. In addition, sample droplet evaporation in a limited area called confined evaporation contributes to nanorod migration and reassembly on the corner of the substrate, enhancing analytes absorption, and substantially lowered the detection limits. By systematically evaluating the substrate performance, we were able to obtain an average enhancement factor of 3.31 × 106. After confined evaporation, the detection limit reached 10-18 M for R6G and for triphenyltin, it achieved 10-9 M. This novel method represents a significant advancement toward SERS application in detecting trace pollutants.
  2. Nurul Najian AB, Engku Nur Syafirah EA, Ismail N, Mohamed M, Yean CY
    Anal Chim Acta, 2016 Jan 15;903:142-8.
    PMID: 26709307 DOI: 10.1016/j.aca.2015.11.015
    In recent years extensive numbers of molecular diagnostic methods have been developed to meet the need of point-of-care devices. Efforts have been made towards producing rapid, simple and inexpensive DNA tests, especially in the diagnostics field. We report on the development of a label-based lateral flow dipstick for the rapid and simple detection of multiplex loop-mediated isothermal amplification (m-LAMP) amplicons. A label-based m-LAMP lateral flow dipstick assay was developed for the simultaneous detection of target DNA template and a LAMP internal control. This biosensor operates through a label based system, in which probe-hybridization and the additional incubation step are eliminated. We demonstrated this m-LAMP assay by detecting pathogenic Leptospira, which causes the re-emerging disease Leptospirosis. The lateral flow dipstick was developed to detect of three targets, the LAMP target amplicon, the LAMP internal control amplicon and a chromatography control. Three lines appeared on the dipstick, indicating positive results for all representative pathogenic Leptospira species, whereas two lines appeared, indicating negative results, for other bacterial species. The specificity of this biosensor assay was 100% when it was tested with 13 representative pathogenic Leptospira species, 2 intermediate Leptospira species, 1 non-pathogenic Leptospira species and 28 other bacteria species. This study found that this DNA biosensor was able to detect DNA at concentrations as low as 3.95 × 10(-1) genomic equivalent ml(-1). An integrated m-LAMP and label-based lateral flow dipstick was successfully developed, promising simple and rapid visual detection in clinical diagnostics and serving as a point-of-care device.
  3. Zhang R, Wang S, Huang X, Yang Y, Fan H, Yang F, et al.
    Anal Chim Acta, 2020 Jan 15;1094:142-150.
    PMID: 31761041 DOI: 10.1016/j.aca.2019.10.012
    α-synuclein is a predominantly expressing neuronal protein for understanding the neurodegenerative disorders. A diagnosing system with aggregated α-synuclein encoded by SNCA gene is necessary to make the precautionary treatment against Parkinson's disease (PD). Herein, gold-nanourchin conjugated anti-α-synuclein antibody was desired as the probe and seeded on single-walled carbon nanotube (SWCN) integrated interdigitated electrode (IDE). The surface morphology of SWCN-modified IDE and gold urchin-antibody conjugates were observed under FESEM, FETEM and AFM, the existing elements were confirmed. Voltammetry analysis revealed that the limit of fibril-formed α-synuclein detection was improved by 1000 folds (1 fM) with gold-nanourchin-antibody modified surface, compared to the surface with only antibody (1 pM). Validating the interaction of α-synuclein by Enzyme-linked Immunosorbent Assay was displayed the detection limit as 10 pM. IDE has a good reproducibility and a higher selectivity on α-synuclein as evidenced by the interactive analysis with the control proteins, PARK1 and DJ-1.
  4. Adzhri R, Md Arshad MK, Gopinath SC, Ruslinda AR, Fathil MF, Ayub RM, et al.
    Anal Chim Acta, 2016 Apr 21;917:1-18.
    PMID: 27026595 DOI: 10.1016/j.aca.2016.02.042
    Field-effect transistors (FETs) have succeeded in modern electronics in an era of computers and hand-held applications. Currently, considerable attention has been paid to direct electrical measurements, which work by monitoring changes in intrinsic electrical properties. Further, FET-based sensing systems drastically reduce cost, are compatible with CMOS technology, and ease down-stream applications. Current technologies for sensing applications rely on time-consuming strategies and processes and can only be performed under recommended conditions. To overcome these obstacles, an overview is presented here in which we specifically focus on high-performance FET-based sensor integration with nano-sized materials, which requires understanding the interaction of surface materials with the surrounding environment. Therefore, we present strategies, material depositions, device structures and other characteristics involved in FET-based devices. Special attention was given to silicon and polyaniline nanowires and graphene, which have attracted much interest due to their remarkable properties in sensing applications.
  5. Hamidon NN, Hong Y, Salentijn GI, Verpoorte E
    Anal Chim Acta, 2018 Feb 13;1000:180-190.
    PMID: 29289307 DOI: 10.1016/j.aca.2017.10.040
    We propose the use of water-based alkyl ketene dimer (AKD) ink for fast and user-friendly patterning of paper microfluidic devices either manually or using an inexpensive XY-plotter. The ink was produced by dissolving hydrophobic AKD in chloroform and emulsifying the solution in water. The emulsification was performed in a warm water bath, which led to an increased rate of the evaporation of chloroform. Subsequent cooling led to the final product, an aqueous suspension of fine AKD particles. The effects of surfactant and AKD concentrations, emulsification procedure, and cooling approach on final ink properties are presented, along with an optimized protocol for its formulation. This hydrophobic agent was applied onto paper using a plotter pen, after which the paper was heated to allow spreading of AKD molecules and chemical bonding with cellulose. A paper surface patterned with the ink (10 g L-1 AKD) yielded a contact angle of 135.6° for water. Unlike organic solvent-based solutions of AKD, this AKD ink does not require a fume hood for its use. Moreover, it is compatible with plastic patterning tools, due to the effective removal of chloroform in the production process to less than 2% of the total volume. Furthermore, this water-based ink is easy to prepare and use. Finally, the AKD ink can also be used for the fabrication of so-called selectively permeable barriers for use in paper microfluidic networks. These are barriers that stop the flow of water through paper, but are permeable to solvents with lower surface energies. We applied the AKD ink to confine and preconcentrate sample on paper, and demonstrated the use of this approach to achieve higher detection sensitivities in paper spray ionization-mass spectrometry (PSI-MS). Our patterning approach can be employed outside of the analytical lab or machine workshop for fast prototyping and small-scale production of paper-based analytical tools, for use in limited-resource labs or in the field.
  6. Mukhtar NH, See HH
    Anal Chim Acta, 2016 08 10;931:57-63.
    PMID: 27282751 DOI: 10.1016/j.aca.2016.04.032
    In this study, the potential for carbonaceous nanomaterials to be used as adsorbents for the mixed matrix membrane (MMM) microextraction and preconcentration of organic pollutants was demonstrated. For this method, multiwall carbon nanotubes (MWCNT) and single layer graphene (SLG) nanoparticles were individually incorporated through dispersion in a cellulose triacetate (CTA) polymer matrix to form a MWCNT-MMM and SLG-MMM, respectively. The prepared membranes were evaluated for the extraction of selected polycyclic aromatic hydrocarbons (PAHs) present in sewage pond water samples. The extraction was performed by dipping a small piece of membrane (7 mm × 7 mm) in a stirred 7.5 mL sample solution to initiate the analyte adsorption. This step was followed by an analyte desorption into 60 μL of methanol prior to high performance liquid chromatography (HPLC) analysis. When the optimum SLG-MMM microextraction technique was applied to spiked sewage pond water samples, the detection limit of the method for the PAHs were in the range of 0.02-0.09 ng/mL, with relative standard deviations of between 1.4% and 7.8%. Enrichment factors of 54-100 were achieved with relative recoveries of 99%-101%. A comparison was also made between the proposed approach and standard solid phase extraction using polymeric bonded octadecyl (C18) cartridges.
  7. Kamaruzaman S, Hauser PC, Sanagi MM, Ibrahim WA, Endud S, See HH
    Anal Chim Acta, 2013 Jun 14;783:24-30.
    PMID: 23726096 DOI: 10.1016/j.aca.2013.04.042
    A simple adsorption/desorption procedure using a mixed matrix membrane (MMM) as extraction medium is demonstrated as a new miniaturized sample pretreatment and preconcentration technique. Reversed-phase particles namely polymeric bonded octadecyl (C18) was incorporated through dispersion in a cellulose triacetate (CTA) polymer matrix to form a C18-MMM. Non-steroidal anti-inflammatory drugs (NSAIDs) namely diclofenac, mefenamic acid and ibuprofen present in the environmental water samples were selected as targeted model analytes. The extraction setup is simple by dipping a small piece of C18-MMM (7 mm × 7 mm) in a stirred 10 mL sample solution for analyte adsorption process. The entrapped analyte within the membrane was then desorbed into 100 μL of methanol by ultrasonication prior to high performance liquid chromatography (HPLC) analysis. Each membrane was discarded after single use to avoid any analyte carry-over effect. Several important parameters, such as effect of sample pH, salting-out effect, sample volume, extraction time, desorption solvent and desorption time were comprehensively optimized. The C18-MMM demonstrated high affinity for NSAIDs spiked in tap and river water with relative recoveries ranging from 92 to 100% and good reproducibility with relative standard deviations between 1.1 and 5.5% (n=9). The overall results obtained were found comparable against conventional solid phase extraction (SPE) using cartridge packed with identical C18 adsorbent.
  8. Saad B, Wai WT, Lim BP, Saleh MI
    Anal Chim Acta, 2007 May 22;591(2):248-54.
    PMID: 17481416
    A flow injection analysis (FIA) procedure for the determination of anisidine value (AV) in palm olein using a triiodide detector is described. Undiluted oil sample and chloramine-T reagent were added to a reaction chamber, and reaction was accelerated by applying a short vortex action (typically for 30 s). After allowing the emulsified oil phase to be separated from the aqueous phase (bottom layer), an aliquot of the aqueous phase (containing unreacted chloramine-T) was aspirated into a carrier stream that contained I(-) where the chloramine-T oxidized the I- to form I3(-) which was finally detected by a flow-through triiodide potentiometric detector. Variables that affect the FIA signals such as size of the reaction chamber, oil and reagent flow rates, chloramine-T concentration, vortex time, time for phase separation, carrier stream pH and injected volume were studied. The optimized FIA procedure is linear over 1.0-23.0 AV. The method exhibits good repeatabililty (R.S.D. of +/-3.16% (n = 4) for the determination of 5.0 AV) and a sampling rate of 40 samples per hour was achieved. Good correlation (r2 = 0.996 (n = 4)) between the proposed method and the manual American Oil Chemists' Society procedure was found when applied to the determination of twenty different types of palm olein samples.
  9. Abu Bakar NB, Makahleh A, Saad B
    Anal Chim Acta, 2012 Sep 12;742:59-66.
    PMID: 22884208 DOI: 10.1016/j.aca.2012.02.045
    An in-vial liquid-liquid microextraction method was developed for the selective extraction of the phenolic acids (caffeic, gallic, cinnamic, ferulic, chlorogenic, syringic, vanillic, benzoic, p-hydroxybenzoic, 2,4-dihydroxybenzoic, o-coumaric, m-coumaric and p-coumaric) in vegetable oil samples. The optimised extraction conditions for 20 g sample were: volume of diluent (n-hexane), 2 mL; extractant, methanol: 5 mM sodium hydroxide (60:40; v/v); volume of extractant, 300 μL (twice); vortex, 1 min; centrifugation, 5 min. Recoveries for the studied phenolic acids were 80.1-119.5%. The simultaneous determination of the phenolic acid extracts was investigated by capillary electrophoresis (CE). Separations were carried out on a bare fused-silica capillary (50 μm i.d.× 40 cm length) involving 25 mM sodium tetraborate (pH 9.15) and 5% methanol as CE background electrolyte in the normal polarity mode, voltage of 30 kV, temperature of 25°C, injection time of 4s (50 mbar) and electropherograms were recorded at 200 nm. The phenolic acids were successfully separated in less than 10 min. The validated in-vial LLME-CE method was applied to the determination of phenolic acids in vegetable oil samples (extra virgin olive oil, virgin olive oil, pure olive oil, walnut oil and grapeseed oil). The developed method shows significant advantages over the current methods as lengthy evaporation step is not required.
  10. Makahleh A, Saad B
    Anal Chim Acta, 2011 May 23;694(1-2):90-4.
    PMID: 21565307 DOI: 10.1016/j.aca.2011.03.033
    A single line flow injection analysis (FIA) method that incorporated a preconcentrator column packed with C(18) particles and capacitively coupled contactless conductivity detector (C(4)D) was developed for the determination of free fatty acid (FFA) in vegetable oils. The carrier stream was methanol/1.5 mM sodium acetate (pH 8) 80:20 (v/v) at a flow rate of 1.0 mL min(-1). Calibration curve was well correlated (r(2)=0.9995) within the range of 1-200 mg L(-1) FFA (expressed as palmitic acid). Sampling rate of 40-60 h(-1) was achieved. Good agreement was found between the standard non-aqueous titrimetry method and the proposed method when applied to the determination of FFA in palm (crude, olein, and refined, bleached and deodorised) and other vegetable (soybean, rice bran, walnut, corn and olive) oils. The proposed method offers distinct advantages over the official method, especially in terms of simplicity, high sampling rate, economy of solvents and sample, offering considerable promise as a low cost automated system that needs minimum human intervention over long periods of time.
  11. Yew CT, Azari P, Choi JR, Li F, Pingguan-Murphy B
    Anal Chim Acta, 2018 Jun 07;1009:81-88.
    PMID: 29422135 DOI: 10.1016/j.aca.2018.01.016
    Point-of-care biosensors are important tools developed to aid medical diagnosis and testing, food safety and environmental monitoring. Paper-based biosensors, especially nucleic acid-based lateral flow assays (LFA), are affordable, simple to produce and easy to use in remote settings. However, the sensitivity of such assays to infectious diseases has always been a restrictive challenge. Here, we have successfully electrospun polycaprolactone (PCL) on nitrocellulose (NC) membrane to form a hydrophobic coating to reduce the flow rate and increase the interaction rate between the targets and gold nanoparticles-detecting probes conjugates, resulting in the binding of more complexes to the capture probes. With this approach, the sensitivity of the PCL electrospin-coated test strip has been increased by approximately ten-fold as compared to the unmodified test strip. As a proof of concept, this approach holds great potential for sensitive detection of targets at point-of-care testing.
  12. Ashraf MA, Liu Z, Peng W, Parsaee Z
    Anal Chim Acta, 2019 Mar 21;1051:120-128.
    PMID: 30661608 DOI: 10.1016/j.aca.2018.11.014
    The ultrasound wave assisted synthesis of a novel ZnWO3/rGO hybrid nono composition (ZnWO3/rGO HNC) as a high performance sensor for formaldehyde (FA) has been reported. Different techniques of analysis such as XRD, FE-SEM, TGA, XPS, HRTEM and BET were applied for morphological and spectroscopic characterization of the ZnWO3/rGO HNC. The sensing evaluation of the constructed sensor showed high selectivity, sensitivity and a linear correlation between achieved responses and concentration of target gas (1-10 ppm) with R2 = 0.993 at temperature of 95 °C. The determination of FA was validated and performed using gas chromatography-mass spectrometry combined by solid phase micro-extraction after derivatization with O-(2,3,4,5,6-pentafluoro-benzyl)-hydroxylamine hydrochloride. Validation was carried out in terms of limit of detection linearity, precision, and recovery. The mechanistic evaluation of sensing behavior of the ZnWO3/rGO HNC was interpreted based on large specific surface area (SSA) to volume, mesoporous structure and the heterojunction between rGO and ZnWO3 at the interface between the rGO and ZnWO3.
  13. Acquah C, Danquah MK, Yon JL, Sidhu A, Ongkudon CM
    Anal Chim Acta, 2015 Aug 12;888:10-8.
    PMID: 26320953 DOI: 10.1016/j.aca.2015.05.050
    The discovery of Systematic Evolution of Ligands by Exponential Enrichment (SELEX) assay has led to the generation of aptamers from libraries of nucleic acids. Concomitantly, aptamer-target recognition and its potential biomedical applications have become a major research endeavour. Aptamers possess unique properties that make them superior biological receptors to antibodies with a plethora of target molecules. Some specific areas of opportunities explored for aptamer-target interactions include biochemical analysis, cell signalling and targeting, biomolecular purification processes, pathogen detection and, clinical diagnosis and therapy. Most of these potential applications rely on the effective immobilisation of aptamers on support systems to probe target species. Hence, recent research focus is geared towards immobilising aptamers as oligosorbents for biodetection and bioscreening. This article seeks to review advances in immobilised aptameric binding with associated successful milestones and respective limitations. A proposal for high throughput bioscreening using continuous polymeric adsorbents is also presented.
  14. Lee ST, Beaumont D, Su XD, Muthoosamy K, New SY
    Anal Chim Acta, 2018 Jun 20;1010:62-68.
    PMID: 29447672 DOI: 10.1016/j.aca.2018.01.012
    Single strand DNA (ssDNA) chimeras consisting of a silver nanoclusters-nucleating sequence (NC) and an aptamer are widely employed to synthesize functional silver nanoclusters (AgNCs) for sensing purpose. Despite its simplicity, this chimeric-templated AgNCs often leads to undesirable turn-off effect, which may suffer from false positive signals caused by interference. In our effort to elucidate how the relative position of NC and aptamer affects the fluorescence behavior and sensing performance, we systematically formulated these NC and aptamer regions at different position in a DNA chimera. Using adenosine aptamer as a model, we tested the adenosine-induced optical response of each design. We also investigated the effect of linker region connecting NC and aptamer, as well as different NC sequence on the sensing performance. We concluded that locating NC sequence at 5'-end exhibited the best response, with immediate fluorescence enhancement observed over a wide linear range (1-2500 μM). Our experimental findings help to explain the emission behavior and sensing performance of chimeric conjugates of AgNCs, providing an important means to formulate a better aptasensor.
  15. Ng SM, Narayanaswamy R
    Anal Chim Acta, 2011 Oct 10;703(2):226-33.
    PMID: 21889638 DOI: 10.1016/j.aca.2011.07.032
    Despite the increasing number of usage of molecularly imprinted polymers (MIPs) in optical sensor application, the correlation between the analytical signals and the binding isotherms has yet to be fully understood. This work investigates the relationship between the signals generated from MIPs sensors to its respective binding affinity variables generated using binding isotherm models. Two different systems based on the imprinting of metal ion and organic compound have been selected for the study, which employed reflectance and fluorescence sensing schemes, respectively. Batch binding analysis using the standard binding isotherm models was employed to evaluate the affinity of the binding sites. Evaluation using the discrete bi-Langmuir isotherm model found both the MIPs studied have generally two classes of binding sites that was of low and high affinities, while the continuous Freundlich isotherm model has successfully generated a distribution of affinities within the investigated analytical window. When the MIPs were incorporated as sensing receptors, the changes in the analytical signal due to different analyte concentrations were found to have direct correlation with the binding isotherm variables. Further data analyses based on this observation have generated robust models representing the analytical performance of the optical sensors. The best constructed model describing the sensing trend for each of the sensor has been tested and demonstrated to give accurate prediction of concentration for a series of spiked analytes.
  16. Wong XY, Quesada-González D, Manickam S, Muthoosamy K
    Anal Chim Acta, 2021 Aug 29;1175:338745.
    PMID: 34330444 DOI: 10.1016/j.aca.2021.338745
    Metal ions homeostasis plays an important role in biological processes. The ability to detect the concentration of metal ions in biological fluids is often challenged by the obvious interference or competitive binding nature of other alkaline metals ions. Common analytical techniques employed for metal ions detection are electrochemical, fluorescence and colorimetric methods. However, most reported metal ions sensors are complicated, time-consuming and involve costly procedures with limited effectiveness. Herein, a nanobiosensor for detecting sodium and potassium ions using folic acid-functionalised reduced graphene oxide-modified RNase A gold nanoclusters (FA-rGO-RNase A/AuNCs) based on fluorescence "turn-off/turn-on" is presented. Firstly, a facile and optimised protocol for the fabrication of RNase A/AuNCs is developed. The activity of RNase A protein after the formation of RNase A/AuNCs is studied. RNase A/AuNCs is then loaded onto FA-rGO, in which FA-rGO is used as a potential carrier and fluorescence quencher for RNase A/AuNCs. Finally, a fluorescence "turn-on" sensing strategy is developed using the as-synthesised FA-rGO-RNase A/AuNCs to detect sodium and potassium ions. The developed nanobiosensor revealed an excellent sensing performance and meets the sensitivity required to detect both sodium and potassium ions. To the best of our knowledge, this is the first work done on determining the RNase A protein activity in RNase A/AuNCs and exploring the potential application of RNase A/AuNCs as a metal ion sensor. This work serves as a proof-of-concept for combining the potential of drug delivery, active targeting and therapy on cancer cells, as well as biosensing of metal ions into a single platform.
  17. Foo PC, Chan YY, Mohamed M, Wong WK, Nurul Najian AB, Lim BH
    Anal Chim Acta, 2017 May 08;966:71-80.
    PMID: 28372729 DOI: 10.1016/j.aca.2017.02.019
    This study highlighted the development of a four target nitrocellulose-based nucleic acid lateral flow immunoassay biosensor in a dry-reagent strip format for interpretation of double-labelled double-stranded amplicons from thermostabilised triplex loop-mediated isothermal amplification assay. The DNA biosensor contained two test lines which captured biotin and texas red labelled amplicons; a LAMP internal amplification control line that captured digoxigenin labelled amplicon; and a chromatography control line that validated the functionality of the conjugated gold nanoparticles and membrane. The red lines on detection pad were generated when the gold nanoparticles conjugated antibody bound to the fluorescein labelled amplicons, and the capture agents bound to their specific hapten on the other 5' end of the double-stranded amplicon. The applicability of this DNA biosensor was demonstrated using amoebiasis-causing Entamoeba histolytica simultaneously with the non-pathogenic but morphologically identical Entamoeba dispar and Entamoeba moshkovskii. The biosensor detection limit was 10 E. histolytica trophozoites, and revealed 100% specificity when it was evaluated against 3 medically important Entamoeba species and 75 other pathogenic microorganisms. Heat stability test showed that the biosensor was stable for at least 181 days at ambient temperature. This ready-to-use and cold-chain-free biosensor facilitated the post-LAMP analysis based on visualisation of lines on strip instead of observation of amplicon patterns in agarose gel.
  18. Ngamdee T, Yin LS, Vongpunsawad S, Poovorawan Y, Surareungchai W, Lertanantawong B
    Anal Chim Acta, 2020 Oct 16;1134:10-17.
    PMID: 33059855 DOI: 10.1016/j.aca.2020.08.018
    DNA strand displacement is an attractive, enzyme-free target hybridization strategy for nano-biosensing. The target DNA induces a strand displacement reaction by replacing the pre-hybridized strand that is labeled with gold nanoparticles (AuNPs). Thus, the amount of displaced-AuNP-labeled strand is proportional to the amount of target DNA in the sample. The use of a magnetogenosensing technique to isolate the target DNA allows for a simple, one-pot detection approach, which minimizes possible carry-over contamination and pipetting errors. We sought a proof-of-concept for this technology in its ability to detect DNA-equivalent of hepatitis E virus (HEV), which causes acute viral hepatitis for which rapid and simple diagnostic methods remain limited. Signal detection was done via visual observation, spectrophotometry, and electrochemistry. The sensor demonstrated good sensitivity with detection limits of 10 pM (visual), 10 pM (spectrophotometry) and 1 fM (electrochemical). This sensor also exhibited high specificity for real target amplicons and could discriminate between perfect and mismatched sequences. Lyophilized biosensor reagents stored at 4 °C, 25 °C, and outdoor ambient temperature, were stable for up to 90, 50, and 40 days, respectively. The integration of magnetic separation and target DNA-induced strand displacement reaction in a dry reagent form makes the sensing platform easy-to-use and suitable for field settings.
  19. Ahmad-Tajudin A, Adler B, Ekström S, Marko-Varga G, Malm J, Lilja H, et al.
    Anal Chim Acta, 2014 Jan 7;807:1-8.
    PMID: 24356215 DOI: 10.1016/j.aca.2013.08.051
    To address immunocapture of proteins in large cohorts of clinical samples high throughput sample processing is required. Here a method using the proteomic sample platform, ISET (integrated selective enrichment target) that integrates highly specific immunoaffinity capture of protein biomarker, digestion and sample cleanup with a direct interface to mass spectrometry is presented. The robustness of the on-ISET protein digestion protocol was validated by MALDI MS analysis of model proteins, ranging from 40 fmol to 1 pmol per nanovial. On-ISET digestion and MALDI MS/MS analysis of immunoaffinity captured disease-associated biomarker PSA (prostate specific antigen) from human seminal plasma are presented.
  20. Zainal-Abidin MH, Hayyan M, Hayyan A, Jayakumar NS
    Anal Chim Acta, 2017 08 01;979:1-23.
    PMID: 28599704 DOI: 10.1016/j.aca.2017.05.012
    With the rapid development of ionic liquid analogues, termed 'deep eutectic solvents' (DESs), and their application in a wide range of chemical and biochemical processes in the past decade, the extraction of bioactive compounds has attracted significant interest. Recently, numerous studies have explored the extraction of bioactive compounds using DESs from diverse groups of natural sources, including animal and plant sources. This review summarizes the-state-of-the-art effort dedicated to the application of DESs in the extraction of bioactive compounds. The aim of this review also was to introduce conventional and recently-developed extraction techniques, with emphasis on the use of DESs as potential extractants for various bioactive compounds, such as phenolic acid, flavonoids, tanshinone, keratin, tocols, terpenoids, carrageenans, xanthones, isoflavones, α-mangostin, genistin, apigenin, and others. In the near future, DESs are expected to be used extensively for the extraction of bioactive compounds from various sources.
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