Displaying publications 21 - 40 of 92 in total

Abstract:
Sort:
  1. Nurul Najian AB, Foo PC, Ismail N, Kim-Fatt L, Yean CY
    Mol Cell Probes, 2019 04;44:63-68.
    PMID: 30876924 DOI: 10.1016/j.mcp.2019.03.001
    This study highlighted the performance of the developed integrated loop-mediated isothermal amplification (LAMP) coupled with a colorimetric DNA-based magnetogenosensor. The biosensor operates through a DNA hybridization system in which a specific designed probe captures the target LAMP amplicons. We demonstrated the magnetogenosensor assay by detecting pathogenic Leptospira, which causes leptospirosis. The color change of the assay from brown to blue indicated a positive result, whereas a negative result was indicated by the assay maintaining its brown color. The DNA biosensor was able to detect DNA at a concentration as low as 200 fg/μl, which is equivalent to 80 genomes/reaction. The specificity of the biosensor assay was 100% when it was evaluated with 172 bacterial strains. An integrated LAMP and probe-specific magnetogenosensor was successfully developed, promising simple and rapid visual detection in clinical diagnostics and service as a point-of-care device.
    Matched MeSH terms: Colorimetry
  2. Lai MY, Bukhari FDM, Zulkefli NZ, Ismail I, Mustapa NI, Soh TST, et al.
    Int J Infect Dis, 2022 Jul;120:132-134.
    PMID: 35472524 DOI: 10.1016/j.ijid.2022.04.036
    OBJECTIVES: Preventing reverse transcription loop-mediated isothermal amplification (RT-LAMP) carryover contamination could be solved by adding deoxyuridine triphosphate (dUTP) and uracil-DNA glycosylase (UDG) into the reaction master mix.

    METHODS: RNA was extracted from nasopharyngeal swab samples by a simple RNA extraction method.

    RESULTS: Testing of 77 samples demonstrated 91.2% sensitivity (95% confidence interval [CI]: 78-98.2%) and 100% specificity (95% confidence interval: 92-100%) using UDG RT-LAMP.

    CONCLUSION: This colorimetric UDG RT-LAMP is a simple-to-use, fast, and easy-to-interpret method, which could serve as an alternative for diagnosis of SARS-CoV-2 infection, especially in remote hospitals and laboratories with under-equipped medical facilities.

    Matched MeSH terms: Colorimetry
  3. Ang HY, Subramani T, Yeap SK, Omar AR, Ho WY, Abdullah MP, et al.
    Exp Ther Med, 2014 Jun;7(6):1733-1737.
    PMID: 24926376
    Immunomodulators are agents that are able to stimulate or inhibit the immune response. The leaf extracts from Potentilla indica and Dendrophthoe pentandra were analyzed in vitro for immunomodulatory activity and an MTT colorimetric assay was conducted to determine the proliferation of mice splenocytes and thymocytes. A bromodeoxyuridine assay was performed to analyze DNA synthesis and the Trypan blue exclusion method was conducted to evaluate the changes in total cell population. The results indicated that treatment with P. indica and D. pentandra produced a time- and dose-dependent increase in cell viability and proliferation. Following 72 h of treatment with P. indica and D. pentandra, thymocyte proliferation was augmented by 18 and 41%, respectively and splenocyte proliferation increased by 35 and 42%, respectively, when compared with untreated cells. The present study demonstrated that these extracts may act as potential immunostimulants and, thus, represent an alternative source of immunomodulatory compounds for the treatment of human immune-mediated diseases.
    Matched MeSH terms: Colorimetry
  4. Tan BL, Norhaizan ME, Chan LC
    PMID: 29977314 DOI: 10.1155/2018/6578648
    Manilkara zapota (L.) P. Royen (family: Sapotaceae) is commonly called sapodilla, or locally known as ciku. The detailed mechanisms underlying Manilkara zapota leaf methanol extract against HeLa human cervical cancer cells have yet to be investigated. Therefore, our present study is designed to investigate the ability to induce apoptosis and the underlying mechanisms of Manilkara zapota leaf methanol extract inducing cytotoxicity in HeLa cells. The apoptotic cell death was assessed using Annexin V-propidium iodide staining. Intracellular reactive oxygen species (ROS) and mitochondrial membrane potential activities were measured using dichlorodihydrofluorescein diacetate and MitoLite Orange, respectively, by NovoCyte Flow Cytometer. Bax and Bcl-2 expression were evaluated using Enzyme-Linked Immunosorbent Assay. Caspase-3 activity was determined using a colorimetric assay. The associated biological interaction pathways were evaluated using quantitative real-time PCR. Our data showed that HeLa cells were relatively more sensitive to Manilkara zapota leaf methanol extract than other cancer cell lines studied. Overall analyses revealed that Manilkara zapota leaf methanol extract can inhibit the viability of HeLa cells, induce mitochondrial ROS generation, and inhibit nuclear factor-kappa B (NF-κB) and epidermal growth factor receptor (EGFR) transcriptional activities. Our results suggested that Manilkara zapota leaf methanol extract might represent a potential anticervical cancer agent.
    Matched MeSH terms: Colorimetry
  5. Thavanathan J, Huang NM, Thong KL
    Biosens Bioelectron, 2014 May 15;55:91-8.
    PMID: 24368225 DOI: 10.1016/j.bios.2013.11.072
    The unique property of gold nanoparticles (Au NP) to induce colour change and the versatility of graphene oxides (GO) in surface modification makes them ideal in the application of colorimetric biosensor. Thus we developed a label free optical method to detect DNA hybridization through a visually observed colour change. The Au NP is conjugated to a DNA probe and is allowed to hybridize with the DNA target to the GO thus causing a change in colour from pinkish-red to purplish blue. Spectrophometry analysis gave a wavelength shift of 22 nm with 1 µM of DNA target. Sensitivity testing using serially diluted DNA conjugated GO showed that the optimum detection was at 63 nM of DNA target with the limit at 8 nM. This proves the possibility for the detection of DNA hybridization through the use of dual nanoparticle system by visual observation.
    Matched MeSH terms: Colorimetry/instrumentation*
  6. Ihtatho D, Fadzil MH, Affandi AM, Hussein SH
    PMID: 18002738
    Psoriasis is a skin disorder which is caused by genetic fault. There is no cure for psoriasis, however, there are many treatment modalities to help control the disease. To evaluate treatment efficacy, PASI (Psoriasis Area and Severity Index) which is the current gold standard method is used to measure psoriasis severity by evaluating the area, erythema, scaliness and thickness of the plaques. However, the calculation of PASI can be tedious and subjective. In this work, we develop a computer vision method that determines one of the PASI parameter, the lesion area. The method isolates healthy (or healed) skin areas from lesion areas by analyzing the hue and chroma information in the CIE L*a*b* colour space. Centroids of healthy skin and psoriasis in the hue-chroma space are determined from selected sample. Euclidean distance of all pixels from each centroid is calculated. Each pixel is assigned to the class with minimum Euclidean distance. The study involves patients from three different ethnic origins having different skin tones. Results obtained show that the proposed method is comparable to the dermatologist visual approach.
    Matched MeSH terms: Colorimetry/methods*
  7. Nugroho H, Fadzil MH, Yap VV, Norashikin S, Suraiya HH
    PMID: 18002737
    In this paper, we describe an image processing scheme to analyze and determine areas of skin that have undergone repigmentation in particular, during the treatment of vitiligo. In vitiligo cases, areas of skin become pale or white due to the lack of skin pigment called melanin. Vitiligo treatment causes skin repigmentation resulting in a normal skin color. However, it is difficult to determine and quantify the amount of repigmentation visually during treatment because the repigmentation progress is slow and moreover changes in skin color can only be discerned over a longer time frame typically 6 months. Here, we develop a digital image analysis scheme that can identify and determine vitiligo skin areas and repigmentation progression on a shorter time period. The technique is based on principal component analysis and independent component analysis which converts the RGB skin image into a skin image that represent skin areas due to melanin and haemoglobin only, followed by segmentation process. Vitiligo skin lesions are identified as skin areas that lack melanin (non-melanin areas). In the initial studies of 4 patients, the method has been able to quantify repigmentation in vitiligo lesion. Hence it is now possible to determine repigmentation progression objectively and treatment efficacy on a shorter time cycle.
    Matched MeSH terms: Colorimetry/methods*
  8. Britton S, Cheng Q, Sutherland CJ, McCarthy JS
    Malar J, 2015;14:335.
    PMID: 26315027 DOI: 10.1186/s12936-015-0848-3
    To detect all malaria infections in elimination settings sensitive, high throughput and field deployable diagnostic tools are required. Loop-mediated isothermal amplification (LAMP) represents a possible field-applicable molecular diagnostic tool. However, current LAMP platforms are limited by their capacity for high throughput.
    Matched MeSH terms: Colorimetry/methods*
  9. Azizah N, Hashim U, Gopinath SCB, Nadzirah S
    Int J Biol Macromol, 2017 Jan;94(Pt A):571-575.
    PMID: 27771413 DOI: 10.1016/j.ijbiomac.2016.10.060
    Nanoparticles have been investigated as flagging tests for the sensitive DNA recognition that can be utilized as a part of field applications to defeat restrictions. Gold nanoparticles (AuNPs) have been widely utilized due to its optical property and capacity to get functionalized with a mixed bag of biomolecules. This study exhibits the utilization of AuNPs functionalized with single-stranded oligonucleotide (AuNP-oligo test) for fast the identification of Human Papillomavirus (HPV). This test is displayed on interdigitated electrode sensor and supported by colorimetric assay. DNA conjugated AuNP has optical property that can be controlled for the applications in diagnostics. With its identification abilities, this methodology incorporates minimal effort, strong reagents and basic identification of HPV.
    Matched MeSH terms: Colorimetry/methods*
  10. Salihu SO, Bakar NKA
    Environ Monit Assess, 2018 May 30;190(6):369.
    PMID: 29850927 DOI: 10.1007/s10661-018-6727-y
    The analysis of total organic carbon (TOC) by the American Public Health Association (APHA) closed-tube reflux colorimetric method requires potassium dichromate (K2Cr2O7), silver sulfate (AgSO4), and mercury (HgSO4) sulfate in addition to large volumes of both reagents and samples. The method relies on the release of oxygen from dichromate on heating which is consumed by carbon associated with organic compounds. The method risks environmental pollution by discharging large amounts of chromium (VI) and silver and mercury sulfates. The present method used potassium monochromate (K2CrO4) to generate the K2Cr2O7 on demand in the first phase. In addition, miniaturizing the procedure to semi microanalysis decreased the consumption of reagents and samples. In the second phase, mercury sulfate was eliminated as part of the digestion mixture through the introduction of sodium bismuthate (NaBiO3) for the removal of chlorides from the sample. The modified method, the potassium monochromate closed-tube colorimetry with sodium bismuthate chloride removal (KMCC-Bi), generates the potassium dichromate on demand and eliminates mercury sulfate. The semi microanalysis procedure leads to a 60% reduction in sample volume and ≈ 33.33 and 60% reduction in monochromate and silver sulfate consumption respectively. The LOD and LOQ were 10.17 and 33.90 mg L-1 for APHA, and 4.95 and 16.95 mg L-1 for KMCC-Bi. Recovery was between 83 to 98% APHA and 92 to 104% KMCC-Bi, while the RSD (%) ranged between 0.8 to 5.0% APHA and 0.00 to 0.62% KMCC-Bi. The method was applied for the UV-Vis spectrometry determination of COD in water and wastewater. Statistics was done by MINITAB 17 or MS Excel 2016. ᅟ Graphical abstract.
    Matched MeSH terms: Colorimetry/methods
  11. Far FE, Al-Obaidi MMJ, Desa MNM
    J Mycol Med, 2018 Sep;28(3):486-491.
    PMID: 29753721 DOI: 10.1016/j.mycmed.2018.04.007
    BACKGROUND: Malassezia furfur is lipodependent yeast like fungus that causes superficial mycoses such as pityriasis versicolor and dandruff. Nevertheless, there are no standard reference methods to perform susceptibility test of Malassezia species yet.

    AIMS: Therefore, in this study, we evaluated the optimized culture medium for growth of this lipophilic yeast using modified leeming-Notman agar and colorimetric resazurin microtiter assay to assess antimycotic activity of fluconazole against M. furfur.

    RESULTS: The result showed that these assays were more adjustable for M. furfur with reliable and reproducible MIC end-point, by confirming antimycotic activity of fluconazole with MIC of 2μg/ml.

    CONCLUSION: We conclude that this method is considered as the rapid and effective susceptibility testing of M. furfur with fluconazole antifungal activity.

    Matched MeSH terms: Colorimetry/methods
  12. Che Sulaiman IS, Chieng BW, Osman MJ, Ong KK, Rashid JIA, Wan Yunus WMZ, et al.
    Mikrochim Acta, 2020 01 15;187(2):131.
    PMID: 31940088 DOI: 10.1007/s00604-019-3893-8
    This review (with 99 refs.) summarizes the progress that has been made in colorimetric (i.e. spectrophotometric) determination of organophosphate pesticides (OPPs) using gold and silver nanoparticles (NPs). Following an introduction into the field, a first large section covers the types and functions of organophosphate pesticides. Methods for colorimetric (spectrophotometric) measurements including RGB techniques are discussed next. A further section covers the characteristic features of gold and silver-based NPs. Syntheses and modifications of metal NPs are covered in section 5. This is followed by overviews on enzyme inhibition-based assays, aptamer-based assays and chemical (non-enzymatic) assays, and a discussion of specific features of colorimetric assays. Several Tables are presented that give an overview on the wealth of methods and materials. A concluding section addresses current challenges and discusses potential future trends and opportunities. Graphical abstractSchematic representation of organophosphate pesticide determinations based on aggregation of nanoparticles (particular silver or gold nanoparticles). This leads to a color change which can be determined visually and monitored by a red shift in the absorption spectrum.
    Matched MeSH terms: Colorimetry/methods*
  13. Abdullah WZ, Idris SZ, Bashkar S, Hassan R
    Singapore Med J, 2009 Jun;50(6):604-9.
    PMID: 19551314
    The fibrinolytic system plays an important role in normal haemostasis and endothelial function. This study was conducted to compare three fibrinolytic markers, i.e. plasminogen, tissue-plasminogen activator (t-PA) and plasminogen activator inhibitor type-1 (PAI-1) between acute stroke and stable non-stroke patients and to investigate the clinical significance of these markers.
    Matched MeSH terms: Colorimetry/methods
  14. Kho CL, Mohd-Azmi ML, Arshad SS, Yusoff K
    J Virol Methods, 2000 Apr;86(1):71-83.
    PMID: 10713378
    A sensitive and specific RT-nested PCR coupled with an ELISA detection system for detecting Newcastle disease virus is described. Two nested pairs of primer which were highly specific to all the three different pathotypes of NDV were designed from the consensus fusion gene sequence. No cross-reactions with other avian infectious agents such as infectious bronchitis virus, infectious bursal disease virus, influenza virus, and fowl pox virus were observed. Based on agarose electrophoresis detection, the RT-nested PCR was about 100 times more sensitive compared to that of a non-nested RT-PCR. To facilitate the detection of the PCR product, an ELISA detection method was then developed to detect the amplified PCR products and it was shown to be ten times more sensitive than gel electrophoresis. The efficacy of the nested PCR-ELISA was also compared with the conventional NDV detection method (HA test) and non-nested RT-PCR by testing against a total of 35 tissue specimens collected from ND-symptomatic chickens. The RT-nested PCR ELISA found NDV positive in 21 (60%) tissue specimens, while only eight (22.9%) and two (5.7%) out of 35 tissue specimens were tested NDV positive by both the non-nested RT-PCR and conventional HA test, respectively. Due to its high sensitivity for the detection of NDV from tissue specimens, this PCR-ELISA based diagnostic test may be useful for screening large number of samples.
    Matched MeSH terms: Colorimetry/methods
  15. Tan KH, Cham HY, Awala H, Ling TC, Mukti RR, Wong KL, et al.
    Nanoscale Res Lett, 2015 Dec;10(1):956.
    PMID: 26058517 DOI: 10.1186/s11671-015-0956-6
    Lubricant oils take significant part in current health and environmental considerations since they are an integral and indispensable component of modern technology. Antioxidants are probably the most important additives used in oils because oxidative deterioration plays a major role in oil degradation. Zeolite nanoparticles (NPs) have been proven as another option as green antioxidants in oil formulation. The anti-oxidative behavior of zeolite NPs is obvious; however, the phenomenon is still under investigation. Herein, a study of the effect of extra-framework cations stabilized on Linde Type L (LTL) zeolite NPs (ca. 20 nm) on inhibition of oxidation in palm oil-based lubricant oil is reported. Hydrophilic LTL zeolites with a Si/Al ratio of 3.2 containing four different inorganic cations (Li(+), Na(+), K(+), Ca(2+)) were applied. The oxidation of the lubricant oil was followed by visual observation, colorimetry, fourier transform infrared (FTIR) spectroscopy, (1)H NMR spectroscopy, total acid number (TAN), and rheology analyses. The effect of extra-framework cations to slow down the rate of oil oxidation and to control the viscosity of oil is demonstrated. The degradation rate of the lubricant oil samples is decreased considerably as the polarizability of cation is increased with the presence of zeolite NPs. More importantly, the microporous zeolite NPs have a great influence in halting the steps that lead to the polymerization of the oils and thus increasing the lifetime of oils.
    Matched MeSH terms: Colorimetry
  16. Mohd Nawi N, Muhamad II, Mohd Marsin A
    Food Sci Nutr, 2015 Mar;3(2):91-9.
    PMID: 25838887 DOI: 10.1002/fsn3.132
    This study focuses on the impact of different wall materials on the physicochemical properties of microwave-assisted encapsulated anthocyanins from Ipomoea batatas. Using the powder characterization technique, purple sweet potato anthocyanin (PSPAs) powders were analysed for moisture content, water activity, dissolution time, hygroscopicity, color and morphology. PSPAs were produced using different wall materials: maltodextrin (MD), gum arabic (GA) and a combination of gum arabic and maltodextrin (GA + MD) at a 1:1 ratio. Each of the wall materials was homogenized to the core material at a core/wall material ratio of 5 and were microencapsulated by microwave-assisted drying at 1100 W. Results indicated that encapsulated powder with the GA and MD combination presented better quality of powder with the lowest value of moisture content and water activity. With respect to morphology, the microcapsule encapsulated with GA + MD showed several dents in coating surrounding its core material, whereas other encapsulated powders showed small or slight dents entrapped onto the bioactive compound. Colorimetric analysis showed changes in values of L, a*, b*, hue and chroma in the reconstituted powder compared to the initial powder.
    Matched MeSH terms: Colorimetry
  17. Abdullah P, Nainggolan H
    Environ Monit Assess, 1991 Oct;19(1-3):423-31.
    PMID: 24233958 DOI: 10.1007/BF00401330
    Phenolic chemicals with their very low taste and odour thresholds, high persistence and toxicity, are of growing concern as water pollutants. The compounds are known to exist in raw water as well as in treated water. The level of phenolic priority pollutants in water within the catchment area of the Linggi River Treatment Plant in Negeri Sembilan, Malaysia, which includes the Linggi river basin, was monitored. The 4-aminoantipyrin colourimetric method was used to determine total phenols whereas capillary column gas chromatography was used to determine the individual compounds. The results show that at most sampling stations, particularly those within the Seremban municipality, the level of phenols was found to exceed the recommended Malaysian standard of 2.0 μg/L(-1) for raw water. This is seen as the direct impact of industrial and urbanization of the area and clearly indicates the unhealthy state of the Linggi river. The results also indicate the need to improve the water quality if the river is going to be used as a source of raw water.
    Matched MeSH terms: Colorimetry
  18. Wan Zuraida Wan Mohd Zain, Siti Nur Lisha Mohd Ghazali, Samsiah Jusoh
    ESTEEM Academic Journal, 2019;15(1):25-32.
    MyJurnal
    Oil palm or Elaeis guineens is a rich natural source of phenolic with flavonoid as the main constituents. These phenolics are potent antioxidants that can be used in the food industry, cosmetics and others. Therefore, the study was aimed to determine the effect of solvents which were methanol, ethyl acetate and hexane also different plant parts which were leaves, frond and fresh fruit bunch toward antioxidant activity (AOA), total phenolic content (TPC) and total flavonoid
    content (TFC). The antioxidant was analysed using the DPPH method, TPC by Ciocalteu assay and TFC by aluminium chloride colorimetric assay. The result from ANOVA indicated that there was a difference (P < 0.05) in the extracting ability of each solvent and different plant parts for AOA, TPC and TFC. Generally, the result suggested that methanol give the highest antioxidant
    activity, TPC and TFC compared to ethyl acetate and hexane. Therefore, the solvent used should be selected properly to allow for a high level of extraction efficiency.
    Matched MeSH terms: Colorimetry
  19. Ali AH, Agustar HK, Hassan NI, Latip J, Embi N, Sidek HM
    Data Brief, 2020 Dec;33:106592.
    PMID: 33318979 DOI: 10.1016/j.dib.2020.106592
    Aromatic (ar)-turmerone is one of the aromatic constituents abundant in turmeric essential oil from Curcuma longa. Ar-turmerone exhibited anti-inflammatory properties. So far, antiplasmodial data for ar-turmerone is still not reported. The data showed the in vitro antiplasmodial effect of ar-turmerone against Plasmodium falciparum 3D7 (chloroquine-sensitive) via Plasmodium lactate dehydrogenase assay (pLDH) and cytotoxic effect against Vero mammalian kidney cells using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) colourimetric assay. Selectivity indexes of ar-turmerone were calculated based on inhibition concentration at 50% of parasite growth (IC50) from MTT and pLDH assays and the effects of ar-turmerone were compared to the antimalarial reference drug chloroquine diphosphate. The inhibitory effect of ar-turmerone at the intraerythrocytic stages of plasmodial lifecycles was evaluated via a stage-dependant susceptibility test. The antiplasmodial and cytotoxic activities of ar-turmerone revealed IC50 values of 46.8 ± 2.4 μM and 820.4 ± 1.5 μM respectively. The selectivity index of ar-turmerone was 17.5. Ar-turmerone suppressed the ring-trophozoite transition stage of the intraerythrocytic life cycle of P. falciparum 3D7.
    Matched MeSH terms: Colorimetry
  20. Citartan M, Tang TH
    Talanta, 2019 Jul 01;199:556-566.
    PMID: 30952298 DOI: 10.1016/j.talanta.2019.02.066
    Aptamers are nucleic acid-based molecular recognition elements that are specific and have high binding affinity against their respective targets. On account of their target recognition capacity, aptamers are widely utilized in a number of applications including diagnostics. This review aims to highlight the recent developments of aptasensors expedient for point-of-care (POC) diagnostics. Significant focus is given on the primary assay formats of aptamers such as fluorescence, electrochemical, surface plasmon resonance (SPR) and colorimetric assays. A potpourri of platforms such as paper-based device, lateral flow assay, portable electrodes, portable SPR and smart phones expedient for point-of-care (POC) diagnostics are discussed. Emphasis is also given on the technicalities and assay configurations associated with the sensors.
    Matched MeSH terms: Colorimetry
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links