Displaying publications 1 - 20 of 93 in total

  1. Jaafar SA, Latif MT, Chian CW, Han WS, Wahid NB, Razak IS, et al.
    Mar Pollut Bull, 2014 Jul 15;84(1-2):35-43.
    PMID: 24930738 DOI: 10.1016/j.marpolbul.2014.05.047
    This study was conducted to determine the composition of surfactants in the sea-surface microlayer (SML) and atmospheric aerosol around the southern region of the Peninsular Malaysia. Surfactants in samples taken from the SML and atmospheric aerosol were determined using a colorimetric method, as either methylene blue active substances (MBAS) or disulphine blue active substances (DBAS). Principal component analysis with multiple linear regressions (PCA-MLR), using the anion and major element composition of the aerosol samples, was used to determine possible sources of surfactants in atmospheric aerosol. The results showed that the concentrations of surfactants in the SML and atmospheric aerosol were dominated by anionic surfactants and that surfactants in aerosol were not directly correlated (p>0.05) with surfactants in the SML. Further PCA-MLR from anion and major element concentrations showed that combustion of fossil fuel and sea spray were the major contributors to surfactants in aerosol in the study area.
    Matched MeSH terms: Colorimetry/methods
  2. Omar N, Loh Q, Tye GJ, Choong YS, Noordin R, Glökler J, et al.
    Sensors (Basel), 2013;14(1):346-55.
    PMID: 24379042 DOI: 10.3390/s140100346
    G-Quadruplex (G-4) structures are formed when G-rich DNA sequences fold into intra- or intermolecular four-stranded structures in the presence of metal ions. G-4-hemin complexes are often effective peroxidase-mimicking DNAzymes that are applied in many detection systems. This work reports the application of a G-rich daunomycin-specific aptamer for the development of an antibody-antigen detection assay. We investigated the ability of the daunomycin aptamer to efficiently catalyze the hemin-dependent peroxidase activity independent of daunomycin. A reporter probe consisting of biotinylated antigen and daunomycin aptamer coupled to streptavidin gold nanoparticles was successfully used to generate a colorimetric readout. In conclusion, the daunomycin aptamer can function as a robust alternative DNAzyme for the development of colorimetric assays.
    Matched MeSH terms: Colorimetry/methods*
  3. Choi JR, Hu J, Gong Y, Feng S, Wan Abas WA, Pingguan-Murphy B, et al.
    Analyst, 2016 05 10;141(10):2930-9.
    PMID: 27010033 DOI: 10.1039/c5an02532j
    Lateral flow assays (LFAs) have been extensively explored in nucleic acid testing (NAT) for medical diagnostics, food safety analysis and environmental monitoring. However, the amount of target nucleic acid in a raw sample is usually too low to be directly detected by LFAs, necessitating the process of amplification. Even though cost-effective paper-based amplification techniques have been introduced, they have always been separately performed from LFAs, hence increasing the risk of reagent loss and cross-contaminations. To date, integrating paper-based nucleic acid amplification into colorimetric LFA in a simple, portable and cost-effective manner has not been introduced. Herein, we developed an integrated LFA with the aid of a specially designed handheld battery-powered system for effective amplification and detection of targets in resource-poor settings. Interestingly, using the integrated paper-based loop-mediated isothermal amplification (LAMP)-LFA, we successfully performed highly sensitive and specific target detection, achieving a detection limit of as low as 3 × 10(3) copies of target DNA, which is comparable to the conventional tube-based LAMP-LFA in an unintegrated format. The device may serve in conjunction with a simple paper-based sample preparation to create a fully integrated paper-based sample-to-answer diagnostic device for point-of-care testing (POCT) in the near future.
    Matched MeSH terms: Colorimetry*
  4. Ahmad Faris AN, Ahmad Najib M, Mohd Nazri MN, Hamzah ASA, Aziah I, Yusof NY, et al.
    Int J Environ Res Public Health, 2022 Aug 25;19(17).
    PMID: 36078284 DOI: 10.3390/ijerph191710570
    Water- and food-related health issues have received a lot of attention recently because food-poisoning bacteria, in particular, are becoming serious threats to human health. Currently, techniques used to detect these bacteria are time-consuming and laborious. To overcome these challenges, the colorimetric strategy is attractive because it provides simple, rapid and accurate sensing for the detection of Salmonella spp. bacteria. The aim of this study is to review the progress regarding the colorimetric method of nucleic acid for Salmonella detection. A literature search was conducted using three databases (PubMed, Scopus and ScienceDirect). Of the 88 studies identified in our search, 15 were included for further analysis. Salmonella bacteria from different species, such as S. Typhimurium, S. Enteritidis, S. Typhi and S. Paratyphi A, were identified using the colorimetric method. The limit of detection (LoD) was evaluated in two types of concentrations, which were colony-forming unit (CFU) and CFU per mL. The majority of the studies used spiked samples (53%) rather than real samples (33%) to determine the LoDs. More research is needed to assess the sensitivity and specificity of colorimetric nucleic acid in bacterial detection, as well as its potential use in routine diagnosis.
    Matched MeSH terms: Colorimetry*
  5. Qin D, Gong Q, Li X, Gao Y, Gopinath SCB, Chen Y, et al.
    Biotechnol Appl Biochem, 2023 Apr;70(2):553-559.
    PMID: 35725894 DOI: 10.1002/bab.2377
    Mycoplasma pneumoniae is a highly infectious bacterium and the major cause of pneumonia especially in school-going children. Mycoplasma pneumoniae affects the respiratory tract, and 25% of patients experience health-related problems. It is important to have a suitable method to detect M. pneumoniae, and gold nanoparticle (GNP)-based colorimetric biosensing was used in this study to identify the specific target DNA for M. pneumoniae. The color of GNPs changes due to negatively charged GNPs in the presence of positively charged monovalent (Na+ ) ions from NaCl. This condition is reversed in the presence of a single-stranded oligonucleotide, as it attracts GNPs but not in the presence of double-stranded DNA. Single standard capture DNA was mixed with optimal target DNA that cannot be adsorbed by GNPs; under this condition, GNPs are not stabilized and aggregate at high ionic strength (from 100 mM). Without capture DNA, the GNPs that were stabilized by capture DNA (from 1 μM) became more stable under high ionic conditions and retaining their red color. The GNPs turned blue in the presence of target DNA at concentrations of 1 pM, and the GNPs retained a red color when there was no target in the solution. This method is useful for the simple, easy, and accurate identification of M. pneumoniae target DNA at higher discrimination and without involving sophisticated equipment, and this method provides a diagnostic for M. pneumoniae.
    Matched MeSH terms: Colorimetry/methods
  6. Syahir Habib, Mohd Yunus Abd Shukor, Nur Adeela Yasid, Wan Lutfi Wan Johari
    Petroleum hydrocarbons remain as the major contaminants that could be found across the world.
    Remediation approach through the utilisation of microbes as the bioremediation means widely
    recognised due to their outstanding values. As a result, scientific reports on the isolation and
    identification of new hydrocarbon-degrading strains were on the rise. Colourimetric-based assays
    are one of the fastest methods to identify the capability of hydrocarbon-degrading strains in both
    qualitative and quantitative assessment. In this study, the hydrocarbon-degrading potential of
    nine bacterial isolates was observed via 2,6-dichlorophenolindophenol (DCPIP) test. Two potent
    diesel-utilising isolates show a distinctive tendency to utilise aromatic (ADL15) and aliphatic
    (ADL36) hydrocarbons. Both isolates prove to be a good candidate for bioremediation of wide
    range of petroleum hydrocarbon components.
    Matched MeSH terms: Colorimetry
  7. Kiwfo K, Woi PM, Seanjum C, Grudpan K
    Talanta, 2022 Jan 01;236:122848.
    PMID: 34635238 DOI: 10.1016/j.talanta.2021.122848
    Paper-based analytical devices (PADs) with four new designs could be fabricated using commercially available home-based scan-and-cut printer. They serve for miniaturised platforms for chemical analysis. Replication analysis of a sample together with the calibration (using the analyte standards at different concentrations) can be completed in a single run, by utilising smartphone as the detector. Some new approaches for choosing detection zones were suggested. The four proposed PAD designs here were used as models in microliter scale operation to demonstrate the well-known chemistries of colorimetric determinations of iron, phosphate, and hardness using 1,10-phenanthroline and simple aqueous guava leaf extract; molybdate, and EBT-EDTA complexometric titration, respectively, through calibrations: where Blue (B) value = 88.2log [Fe3+] - 80.8, R2 = 0.989; B value = 1.75 [Fe3+] + 0.198, R2 = 0.999; Grey scale (I) value = 1.77 [Fe3+] - 1.22, R2 = 0.997; Red (R) value = 16.1log [PO43-] + 8.95, R2 = 0.999; Hue (H) value = 43.3log [Ca2+] + 233, R2 = 0.994, respectively. For the hardness, using one of the PAD designs, true titration was also possible. Applications of the proposed devices and procedures were demonstrated for real world samples with validation. Additionally, kinetic study of the molybdenum blue for phosphate was demonstrated using one of the PADs.
    Matched MeSH terms: Colorimetry
  8. Mohd Ali M, Hashim N, Bejo SK, Shamsudin R
    J Food Sci Technol, 2017 Oct;54(11):3650-3657.
    PMID: 29051660 DOI: 10.1007/s13197-017-2826-y
    The potential of laser light backscattering imaging was investigated for monitoring color parameters of seeded and seedless watermelons during storage. Two watermelon cultivars were harvested and stored for 3 weeks with seven measuring storage days (0, 4, 8, 12, 15, 18, and 21). The color parameters of watermelons were monitored using the conventional colorimetric methods (L*, a*, b*, C*, H*, and ∆E*) and laser light backscattering imaging system. A laser diode emitting at 658 nm and 30 mW power was used as a light source to obtain the backscattering image. The backscattering images were evaluated by the extraction of backscattering parameters based on the mean pixel values. The results showed that a good color prediction was achieved by the seedless watermelon with the R2 are all above 0.900. Thus, the application of the laser light backscattering imaging can be used for evaluating the color parameters of watermelons during the storage period.
    Matched MeSH terms: Colorimetry
  9. Zamzuri NA, Abd-Aziz S, Rahim RA, Phang LY, Alitheen NB, Maeda T
    J Appl Microbiol, 2014 Apr;116(4):903-10.
    PMID: 24314059 DOI: 10.1111/jam.12410
    To isolate a bacterial strain capable of biotransforming ferulic acid, a major component of lignin, into vanillin and vanillic acid by a rapid colorimetric screening method.
    Matched MeSH terms: Colorimetry/methods*
  10. Lau YL, Lai MY, Teoh BT, Abd-Jamil J, Johari J, Sam SS, et al.
    PLoS One, 2015;10(9):e0138694.
    PMID: 26384248 DOI: 10.1371/journal.pone.0138694
    Dengue is usually diagnosed by isolation of the virus, serology or molecular diagnostic methods. Several commercial kits for the diagnosis of dengue are existing, but concerns have arisen regarding to the affordability and performance characteristics of these kits. Hence, the loop-mediated isothermal amplification (LAMP) is potentially ideal to be used especially in resource limited environments. Serum was collected from healthy donors and patients diagnosed with dengue infection. RNA extracted from the serum samples were tested by reverse-transcription-LAMP assay developed based on 3'-NCR gene sequences for DENV 1-4. Results were interpreted by a turbidity meter in real time or visually at the end of the assay. Sensitivity and specificity of RT-LAMP results were calculated and compared to qRT-PCR and ELISA. RT-LAMP is highly sensitive with the detection limit of 10 RNA copies for all serotypes. Dengue virus RNA was detected in all positive samples using RT-LAMP and none of the negative samples within 30-45 minutes. With continuing efforts in the optimization of this assay, RT-LAMP may provide a simple and reliable test for detecting DENV in areas where dengue is prevalent.
    Matched MeSH terms: Colorimetry/methods*
  11. Amran EN, Sudik S, Omar AF, Mail MH, Seeni A
    Photodiagnosis Photodyn Ther, 2019 Sep;27:380-384.
    PMID: 31301437 DOI: 10.1016/j.pdpdt.2019.07.006
    The objective of this research is to examine the relationship between the color changes of phenol red and the growth of cancer cells, i.e., HeLa and DU145 cells, over a specific period of time. Normal mouse skin fibroblasts (L929 cells) were used as a reference. In this research, the color changes of phenol red due to the acidification of the cell culture medium from the growth of the cells over a period of nine hours showed potential colorimetric characteristics of cancer cells. The color changes of phenol red were observed using visible absorbance spectroscopy. The transformation of the absorbance spectra into coefficients of determination against the examined range of wavelengths created a distinctive spectral signature that signifies phenol red discoloration in cancer and normal cell culture lines.
    Matched MeSH terms: Colorimetry/methods*
  12. Arul P, Nandhini C, Huang ST, Gowthaman NSK, Huang CH
    Food Chem, 2023 Jul 15;414:135747.
    PMID: 36841102 DOI: 10.1016/j.foodchem.2023.135747
    A simple and rapid screening of biomarkers in clinical and food matrices is urgently needed to diagnose cardiovascular diseases. The cholesterol (Chol) and hydrogen peroxide (H2O2) are critical bio-indicators, which require more inventive detection techniques to be applied to real food, and bio-samples. In this study, a robust dual sensor was developed for Chol and H2O2 using hybrid catalyst. Bovine serum albumin (BSA)-capped nanocatalyst was potentially catalyzed 3,3',5,5'-tetramethylbenzidine (TMB), and H2O2. The enzymatic nanoelectrocatalyst delivered a wide range of signaling concentrations from 250 nM to 3.0 mM and 100 nM to 10 mM, limit of detection (LOD) of 53.2 nM and 18.4 nM for Chol and H2O2. The cholesterol oxidase-BSA-AuNPs-metal-free organic framework (ChOx-BSA-AuNPs-MFOF) based electrode surface effectively operated in live-cells and real-food samples. The enzymatic sensor exhibits adequate recovery of real-food samples (96.96-99.44%). Finally, the proposed system is a suitable choice for the potential applications of Chol and H2O2 in clinical and food chemistry.
    Matched MeSH terms: Colorimetry/methods
  13. Idros N, Ho MY, Pivnenko M, Qasim MM, Xu H, Gu Z, et al.
    Sensors (Basel), 2015;15(6):12891-905.
    PMID: 26046595 DOI: 10.3390/s150612891
    This proof-of-concept study proposes a novel sensing mechanism for selective and label-free detection of 2,4,6-trinitrotoluene (TNT). It is realized by surface chemistry functionalization of silica nanoparticles (NPs) with 3-aminopropyl-triethoxysilane (APTES). The primary amine anchored to the surface of the silica nanoparticles (SiO2-NH2) acts as a capturing probe for TNT target binding to form Meisenheimer amine-TNT complexes. A colorimetric change of the self-assembled (SAM) NP samples from the initial green of a SiO2-NH2 nanoparticle film towards red was observed after successful attachment of TNT, which was confirmed as a result of the increased separation between the nanoparticles. The shift in the peak wavelength of the reflected light normal to the film surface and the associated change of the peak width were measured, and a merit function taking into account their combined effect was proposed for the detection of TNT concentrations from 10-12 to 10-4 molar. The selectivity of our sensing approach is confirmed by using TNT-bound nanoparticles incubated in AptamerX, with 2,4-dinitrotoluene (DNT) and toluene used as control and baseline, respectively. Our results show the repeatable systematic color change with the TNT concentration and the possibility to develop a robust, easy-to-use, and low-cost TNT detection method for performing a sensitive, reliable, and semi-quantitative detection in a wide detection range.
    Matched MeSH terms: Colorimetry
  14. Noor Raihana, A.R., Marikkar, J.M.N., Jaswir, I., Nurrulhidayah, A.F., Miskandar, M.S.
    A study was carried out to compare the cookie dough properties and cookie quality made out
    of pink guava oil-palm stearin blends and lard (LD). Since LD is prohibited under religious
    restrictions, plant shortenings were prepared by mixing pink guava seed oil with palm stearin
    (PGO/PS) in different ratios: PGO-1, 40:60; PGO-2, 45:55; PGO-3, 50:50; PGO-4; 55:45 as
    replacement. The effect of these formulated plant-based shortenings and LD shortening were
    compared on dough rheological properties and cookie quality. Rheology and hardness of the
    cookie dough were evaluated using Texture Analyser (TA). Cookie hardness was evaluated
    with TA while cookie surface colors were measured using the CIE L*a*b* colorimetric system.
    Among the samples, cookies made out of PGO-2 with the ratio 45:55 (PGO:PS) performed the
    best substitute for LD to be used as shortening in cookies. PGO-2 also displayed the closest
    similarity to LD in cookies for hardness, size and thickness, cracking size as well as colour.
    As PGO-2 was a shortening formulated with plant-based ingredients, it could comply with the
    halal and toyyiban requirements.
    Matched MeSH terms: Colorimetry
  15. Buttery JE, de Witt GF, Omar Ahmad U
    Med J Malaya, 1968 Sep;23(1):54-7.
    PMID: 4237558
    Matched MeSH terms: Colorimetry
  16. Nur Hazimah Abdul Halim, Norfazrin Mohd Hanif, Mohamed Rozali Othman, Mohd Talib Latif
    Sains Malaysiana, 2010;39:175-179.
    Surfactants in the atmosphere may act as cloud condensation nuclei, with a potentially negative impact on the global climate. Therefore, accurate determination of surfactants is crucial in order to investigate the possible effects of surfactants on the atmosphere. The aim of this study was to identify the optimum sampling method for measuring the maximum quantity of surfactants present in ambient air. Air samples were collected using a range of air sampling pumps that were made to vary in terms of flow rate, storage period, type of absorbing solution and the characteristics of the impinger tube. Samples obtained were analysed by colourimetry for anionic and cationic surfactants as methylene blue-active substances (MBAS) and disulphine blue-active substances (DBAS), respectively. Absorbance was measured at 650 nm for MBAS and 628 nm for DBAS using UV-visible spectrophotometer. We found that the optimum sampling method consisted of an absorbent solution (deionised water, buffer solution and methylene blue/disulphine blue solution) with the flow rate of 1.0 L/min. The concentration of surfactants in all sampling methods remained constant regardless of the storage period (1 day and 4 days), indicating that surfactants in the absorbing solution are quite stable. Covering the impinger tube was shown to influence the amount of both anionic and cationic surfactants detected.
    Matched MeSH terms: Colorimetry
  17. Chew N, Noor Azhar AM, Bustam A, Azanan MS, Wang C, Lum LCS
    PLoS Negl Trop Dis, 2020 09;14(9):e0008562.
    PMID: 32881914 DOI: 10.1371/journal.pntd.0008562
    BACKGROUND: Dengue is a systemic and dynamic disease with symptoms ranging from undifferentiated fever to dengue shock syndrome. Assessment of patients' severity of dehydration is integral to appropriate care and management. Urine colour has been shown to have a high correlation with overall assessment of hydration status. This study tests the feasibility of measuring dehydration severity in dengue fever patients by comparing urine colour captured by mobile phone cameras to established laboratory parameters.

    METHODOLOGY/PRINCIPAL FINDINGS: Photos of urine samples were taken in a customized photo booth, then processed using Adobe Photoshop to index urine colour into the red, green, and blue (RGB) colour space and assigned a unique RGB value. The RGB values were then correlated with patients' clinical and laboratory hydration indices using Pearson's correlation and multiple linear regression. There were strong correlations between urine osmolality and the RGB of urine colour, with r = -0.701 (red), r = -0.741 (green), and r = -0.761 (blue) (all p-value <0.05). There were strong correlations between urine specific gravity and the RGB of urine colour, with r = -0.759 (red), r = -0.785 (green), and r = -0.820 (blue) (all p-value <0.05). The blue component had the highest correlations with urine specific gravity and urine osmolality. There were moderate correlations between RGB components and serum urea, at r = -0.338 (red), -0.329 (green), -0.360 (blue). In terms of urine biochemical parameters linked to dehydration, multiple linear regression studies showed that the green colourimetry code was predictive of urine osmolality (β coefficient -0.082, p-value <0.001) while the blue colourimetry code was predictive of urine specific gravity (β coefficient -2,946.255, p-value 0.007).

    CONCLUSIONS/SIGNIFICANCE: Urine colourimetry using mobile phones was highly correlated with the hydration status of dengue patients, making it a potentially useful hydration status tool.

    Matched MeSH terms: Colorimetry/instrumentation; Colorimetry/methods*
  18. Hussain H, Mohd Fuat AR, Vimala B, Ghazali HM
    Trop Biomed, 2011 Aug;28(2):351-61.
    PMID: 22041756
    Assessment of amino acid decarboxylase activity can be conducted using tubed broth or plated agar. In this study, the test was carried out in microtitre plates containing lysine, ornithine, arginine, tyrosine, tryptophan, phenylalanine or histidine as biogenic amine precursors. Møller decarboxylase base broth (MDB) with or without 1% of a known amino acid were added to wells of a 96 well-microtitre plate. The wells were inoculated with Escherichia coli, Klebsiella pneumoniae, Acinetobacter anitratus or Staphylococcus aureus to the final concentration of 6.0 x 10(7) cfu/ml and incubated at 35ºC. The absorbance of the culture broth was read at 570 nm at 0, 1.0, 2.0, 3.0, 4.0, 5.5, 6.5 and 7.5 hour. Comparison of means of A'(570) between 0 hour and a specified incubation time was determined statistically. Positive decarboxylase activities were detected in the media inoculated with E. coli and K. pneumoniae in less than 6 hours. The current method is suitable for immediate producers of amino acid decarboxylase enzymes. It costs less as it uses less amino acid and it has the potential to be used for screening aliquots of food materials for amino acid decarboxylase activities.
    Matched MeSH terms: Colorimetry/economics; Colorimetry/methods
  19. Lai MY, Tang SN, Lau YL
    Am J Trop Med Hyg, 2021 Jun 15;105(2):375-377.
    PMID: 34129521 DOI: 10.4269/ajtmh.21-0150
    Coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been spreading rapidly all over the world. In the absence of effective treatments or a vaccine, there is an urgent need to develop a more rapid and simple detection technology of COVID-19. We describe a WarmStart colorimetric reverse transcription-loop-mediated isothermal amplification (RT-LAMP) assay for the detection of SARS-CoV-2. The detection limit for this assay was 1 copy/µL SARS-CoV-2. To test the clinical sensitivity and specificity of the assay, 37 positive and 20 negative samples were used. The WarmStart colorimetric RT-LAMP had 100% sensitivity and specificity. End products were detected by direct observation, thereby eliminating the need for post-amplification processing steps. WarmStart colorimetric RT-LAMP provides an opportunity to facilitate virus detection in resource-limited settings without a sophisticated diagnostic infrastructure.
    Matched MeSH terms: Colorimetry/methods*; Colorimetry/standards
  20. Nilghaz A, Wicaksono DH, Gustiono D, Abdul Majid FA, Supriyanto E, Abdul Kadir MR
    Lab Chip, 2012 Jan 7;12(1):209-18.
    PMID: 22089026 DOI: 10.1039/c1lc20764d
    This paper describes the fabrication of microfluidic cloth-based analytical devices (μCADs) using a simple wax patterning method on cotton cloth for performing colorimetric bioassays. Commercial cotton cloth fabric is proposed as a new inexpensive, lightweight, and flexible platform for fabricating two- (2D) and three-dimensional (3D) microfluidic systems. We demonstrated that the wicking property of the cotton microfluidic channel can be improved by scouring in soda ash (Na(2)CO(3)) solution which will remove the natural surface wax and expose the underlying texture of the cellulose fiber. After this treatment, we fabricated narrow hydrophilic channels with hydrophobic barriers made from patterned wax to define the 2D microfluidic devices. The designed pattern is carved on wax-impregnated paper, and subsequently transferred to attached cotton cloth by heat treatment. To further obtain 3D microfluidic devices having multiple layers of pattern, a single layer of wax patterned cloth can be folded along a predefined folding line and subsequently pressed using mechanical force. All the fabrication steps are simple and low cost since no special equipment is required. Diagnostic application of cloth-based devices is shown by the development of simple devices that wick and distribute microvolumes of simulated body fluids along the hydrophilic channels into reaction zones to react with analytical reagents. Colorimetric detection of bovine serum albumin (BSA) in artificial urine is carried out by direct visual observation of bromophenol blue (BPB) colour change in the reaction zones. Finally, we show the flexibility of the novel microfluidic platform by conducting a similar reaction in a bent pinned μCAD.
    Matched MeSH terms: Colorimetry/instrumentation; Colorimetry/methods
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