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1.
Chem Pharm Bull (Tokyo) ; 71(10): 766-774, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37779078

RESUMO

One of the most lethal cancers, glioblastoma (GBM), affects 14.5% of all central nervous system (CNS) tumors. Patients diagnosed with GBM have a meager median overall survival (OS) of 15 months. Extensive genetic analysis has shown that many dysregulated pathways, including the Wnt/ß-catenin signaling system, contribute to the pathogenicity of GBM. Paclitaxel (PTX) and temozolomide (TMZ) are recognized to have therapeutic potential in several types of cancer, including GBM. This work aimed to examine the impact of PTX and TMZ on the human glioma cell lines U251 and T98G using molecular docking simulations and gene expression profiles in the Wnt/ß-catenin signaling pathway. Standard procedure for Molecular Docking simulation, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity assay, and Flow Cytometry assay was used. Genes implicated in the Wnt/ß-catenin signaling pathway, including Dvl, Axin, APC, ß-catenin, and glycogen synthase kinase3-ß (GSK3ß), were subjected to real-time PCR. The estimated parameters for targets revealed that the average binding energy and inhibition constant (Ki) for the DVL, ß-Catenin, and GSK3ß, when targeted by PTX, were - 5.01 kcal/mol, - 5.4 kcal/mol, and - 9.06 kcal/mol, respectively. This energy range was - 6.34 kcal/mol for DVL, - 5.52 kcal/mol for ß-Catenin, and - 5.66 kcal/mol for GSK3ß as a result of TMZ's inhibitory actions. Gene expression analyses indicated that PTX and PTX/TMZ suppressed GSK3ß (p < 0.05). GSK3ß from the Wnt/ß-catenin signaling pathway was significantly targeted by PTX alone, and adding TMZ to PTX may improve the efficacy of glioblastoma treatment. In addition, the GSK3ß gene may help GBM therapy strategies as a potential PTX target.


Assuntos
Glioblastoma , Humanos , Temozolomida/farmacologia , Temozolomida/uso terapêutico , Glioblastoma/tratamento farmacológico , Simulação de Acoplamento Molecular , beta Catenina/genética , beta Catenina/metabolismo , beta Catenina/uso terapêutico , Glicogênio Sintase Quinase 3 beta/genética , Glicogênio Sintase Quinase 3 beta/metabolismo , Via de Sinalização Wnt , Paclitaxel/farmacologia , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos , Expressão Gênica , Proliferação de Células
2.
Artigo em Inglês | MEDLINE | ID: mdl-36078284

RESUMO

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.


Assuntos
Colorimetria , Ácidos Nucleicos , Humanos , Limite de Detecção , Salmonella/genética , Sensibilidade e Especificidade
3.
Polymers (Basel) ; 14(18)2022 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-36145871

RESUMO

A medication's approximate release profile should be sustained in order to generate the desired therapeutic effect. The drug's release site, duration, and rate must all be adjusted to the drug's therapeutic aim. However, when designing drug delivery systems, this may be a considerable hurdle. Electrospinning is a promising method of creating a nanofibrous membrane since it enables drugs to be placed in the nanofiber composite and released over time. Nanofiber composites designed through electrospinning for drug release purposes are commonly constructed of simple structures. This nanofiber composite produces matrices with nanoscale fiber structure, large surface area to volume ratio, and a high porosity with small pore size. The nanofiber composite's large surface area to volume ratio can aid with cell binding and multiplication, drug loading, and mass transfer processes. The nanofiber composite acts as a container for drugs that can be customized to a wide range of drug release kinetics. Drugs may be electrospun after being dissolved or dispersed in the polymer solution, or they can be physically or chemically bound to the nanofiber surface. The composition and internal structure of the nanofibers are crucial for medicine release patterns.

4.
Pharmaceutics ; 14(8)2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-36015322

RESUMO

Aggressive glioblastoma (GBM) has no known treatment as a primary brain tumor. Since the cancer is so heterogeneous, an immunosuppressive tumor microenvironment (TME) exists, and the blood-brain barrier (BBB) prevents chemotherapeutic chemicals from reaching the central nervous system (CNS), therapeutic success for GBM has been restricted. Drug delivery based on nanocarriers and nanotechnology has the potential to be a handy tool in the continuing effort to combat the challenges of treating GBM. There are various new therapies being tested to extend survival time. Maximizing therapeutic effectiveness necessitates using many treatment modalities at once. In the fight against GBM, combination treatments outperform individual ones. Combination therapies may be enhanced by using nanotechnology-based delivery techniques. Nano-chemotherapy, nano-chemotherapy-radiation, nano-chemotherapy-phototherapy, and nano-chemotherapy-immunotherapy for GBM are the focus of the current review to shed light on the current status of innovative designs.

5.
Bioelectrochemistry ; 143: 107952, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34600402

RESUMO

The diagnosis of hepatitis B virus (HBV) and monitoring of the vaccination efficiency against HBV require real-time analysis. The presence of antibody against hepatitis B virus surface antigen (anti-HBsAg) as a result of HBV infection and/or immunization may indicate individual immune status towards HBV. This study investigated the ability of a bio-nanogate-based displacement immunosensing strategy in detecting anti-HBsAg antibody, via nonspecific-binding between polyamidoamine dendrimers encapsulated gold nanoparticles (PAMAM-Au) and the 'antigenic determinant' region (aD) of HBsAg. For this purpose, maltose binding protein harbouring the aD region (MBP-aD) was synthesized as a bioreceptor and immobilized on the screen-printed carbon electrode (SPCE). Following that, PAMAM-Au was deposited on MBP-aD, forming the 'gate' and was used as a monitoring agent. Under optimal conditions, the high specificity of anti-HBsAg antibody towards MBP-aD displaced PAMAM-Au causing the decrement of anodic peak in differential pulse voltammetry (DPV) analysis. The signal changes were proportionally related to the concentration of anti-HBsAg antibody, in a range of 1 - 1000 mIU/mL with a limit of detection (LOD) of 2.5 mIU/mL. The results also showed high specificity and selectivity of the immunosensor platform in detecting anti-HBsAg antibody both in spiked buffer and human serum samples.


Assuntos
Técnicas Biossensoriais
6.
Drug Deliv Transl Res ; 12(5): 1253-1269, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-34405338

RESUMO

Glioblastoma multiforme (GBM) is the most prevalent form of brain tumor, which generally has a poor prognosis. According to consensus, recurrence of the tumor and chemotherapy resistance acquisition are the two distinguishing features of GBM originated from glioblastoma stem cells (GSCs). To eliminate these obstacles inherent in GBM chemotherapy, targeting GSCs through a smart drug delivery system has come to the front position of GBM therapeutics. In this study, B19 aptamer (Apt)-conjugated polyamidoamine (PAMAM) G4C12 dendrimer nanoparticles (NPs), called Apt-NPs, were formulated for the co-delivery of paclitaxel (PTX) and temozolomide (TMZ) to U-87 stem cells. These drugs were loaded using a double emulsification solvent evaporation method. As a result, drug-loaded Apt-NPs significantly inhibited the tumor growth of U-87 stem cells, by the initiation of apoptosis via the downregulation of autophagic and multidrug resistance (MDR) genes. Additionally, by their downregulation by qPCR of CD133, CD44, SOX2, and the canonical Wnt/ß-catenin pathway, cell proliferation has substantially decreased. Altogether, the results demonstrate that this intelligent drug co-delivery system is capable of effectively transferring PTX and TMZ to U-87 stem cells and without any toxic effect on Apt-NPs alone to U-87 stem cells. Furthermore, the designed dendrimer-based pharmaceutical system along with single-stranded B19 aptamer might be utilized as a new therapeutic strategy for the treatment of U-87 stem cells drug resistance in the GBM.


Assuntos
Neoplasias Encefálicas , Dendrímeros , Glioblastoma , Apoptose , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Encefálicas/metabolismo , Linhagem Celular Tumoral , Resistência a Medicamentos , Resistencia a Medicamentos Antineoplásicos , Glioblastoma/tratamento farmacológico , Glioblastoma/metabolismo , Humanos , Paclitaxel/farmacologia , Células-Tronco , Temozolomida/farmacologia , Temozolomida/uso terapêutico
7.
Biomolecules ; 11(12)2021 12 09.
Artigo em Inglês | MEDLINE | ID: mdl-34944493

RESUMO

CD44, a non-kinase cell surface transmembrane glycoprotein, has been widely implicated as a cancer stem cell (CSC) marker in several cancers. Cells overexpressing CD44 possess several CSC traits, such as self-renewal and epithelial-mesenchymal transition (EMT) capability, as well as a resistance to chemo- and radiotherapy. The CD44 gene regularly undergoes alternative splicing, resulting in the standard (CD44s) and variant (CD44v) isoforms. The interaction of such isoforms with ligands, particularly hyaluronic acid (HA), osteopontin (OPN) and matrix metalloproteinases (MMPs), drive numerous cancer-associated signalling. However, there are contradictory results regarding whether high or low CD44 expression is associated with worsening clinicopathological features, such as a higher tumour histological grade, advanced tumour stage and poorer survival rates. Nonetheless, high CD44 expression significantly contributes to enhanced tumourigenic mechanisms, such as cell proliferation, metastasis, invasion, migration and stemness; hence, CD44 is an important clinical target. This review summarises current research regarding the different CD44 isoform structures and their roles and functions in supporting tumourigenesis and discusses CD44 expression regulation, CD44-signalling pathways and interactions involved in cancer development. The clinical significance and prognostic value of CD44 and the potential of CD44 as a therapeutic target in cancer are also addressed.


Assuntos
Processamento Alternativo , Receptores de Hialuronatos/genética , Neoplasias/patologia , Progressão da Doença , Transição Epitelial-Mesenquimal , Regulação Neoplásica da Expressão Gênica , Humanos , Receptores de Hialuronatos/metabolismo , Gradação de Tumores , Estadiamento de Neoplasias , Neoplasias/genética , Neoplasias/metabolismo , Células-Tronco Neoplásicas/metabolismo , Prognóstico , Análise de Sobrevida
9.
Front Oncol ; 11: 642719, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33869033

RESUMO

Glioblastoma multiforme (GBM) is one of the most lethal forms of primary brain tumors. Glioblastoma stem cells (GSCs) play an undeniable role in tumor development by activating multiple signaling pathways such as Wnt/ß-catenin and PI3K/AKT/mTOR that facilitate brain tumor formation. CD133, a transmembrane glycoprotein, has been used to classify cancer stem cells (CSCs) in GBM. The therapeutic value of CD133 is a biomarker of the CSC in multiple cancers. It also leads to growth and recurrence of the tumor. More recent findings have confirmed the association of telomerase/TERT with Wnt/ß-catenin and the PI3K/AKT/mTOR signaling pathways. Advance studies have shown that crosstalk between CD133, Wnt/ß-catenin, and telomerase/TERT can facilitate GBM stemness and lead to therapeutic resistance. Mechanistic insight into signaling mechanisms downstream of surface biomarkers has been revolutionized by facilitating targeting of tumor-specific molecular deregulation. This review also addresses the importance of interplay between CD133, Wnt/ß-catenin and TERT signaling pathways in GSCs and outlines the future therapeutic goals for glioblastoma treatment.

10.
Cells ; 9(5)2020 05 16.
Artigo em Inglês | MEDLINE | ID: mdl-32429463

RESUMO

Gliomas are the most frequent and deadly form of human primary brain tumors. Among them, the most common and aggressive type is the high-grade glioblastoma multiforme (GBM), which rapidly grows and renders patients a very poor prognosis. Meanwhile, cancer stem cells (CSCs) have been determined in gliomas and play vital roles in driving tumor growth due to their competency in self-renewal and proliferation. Studies of gliomas have recognized CSCs via specific markers. This review comprehensively examines the current knowledge of the most significant CSCs markers in gliomas in general and in glioblastoma in particular and specifically focuses on their outlook and importance in gliomas CSCs research. We suggest that CSCs should be the superior therapeutic approach by directly targeting the markers. In addition, we highlight the association of these markers with each other in relation to their cascading pathways, and interactions with functional miRNAs, providing the role of the networks axes in glioblastoma signaling pathways.


Assuntos
Biomarcadores Tumorais/metabolismo , Neoplasias Encefálicas/metabolismo , Glioblastoma/metabolismo , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/patologia , Redes Reguladoras de Genes , Glioblastoma/genética , Glioblastoma/patologia , Humanos , MicroRNAs/genética , MicroRNAs/metabolismo , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia
11.
Colloids Surf B Biointerfaces ; 185: 110623, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31735420

RESUMO

Bio-nanogate involves synthesized or natural molecules as a 'gate' towards bioreceptors and responds upon the presence of targeted analytes in nanoscale dimension. Development of bio-nanogate improves analyte selectivity and signal response across various types of biosensors. The versatility of PAMAM dendrimers to form conjugates with guest molecules, such as proteins can be utilized in forming a bio-nanogate. PAMAM interaction with peptide bioreceptor for antibody detection is of interest in this study. This study investigated the interaction of synthesized immunogenic 'a' determinant (aD) region of hepatitis B virus surface antigen (HBsAg) with PAMAM G4 and anti-HBsAg antibody, as a potential bio-nanogate for anti-HBsAg detection. The aD peptide fused with maltose binding protein (MBP), was confirmed with Western blotting. Nano-Differential Scanning Fluorimetry (nano-DSF) study revealed that the interaction of MBP-aD with anti-HBsAg indicated a higher thermal stability as compared to its interaction with PAMAM G4. Electrochemical impedance spectroscopy showed that a higher binding constant of MBP-aD interaction with anti-HBsAg (0.92 µM-1) was observed at maximum saturation, as compared with PAMAM G4 (0.07 µM-1). Thermodynamic parameters demonstrated that MBP-aD interacted with anti-HBsAg and PAMAM G4, through van der Waals and hydrogen bonding. These analyses suggest that the weak interaction of MBP-aD and PAMAM G4 may form a potential bio-nanogate. It is hypothesized that the presence of anti-HBsAg has a higher affinity towards MBP-aD which may displace PAMAM G4 in the anti-HBsAg detection system. This interaction study is crucial as an initial platform of using peptide-PAMAM as a bio-nanogate in an antibody detection system.


Assuntos
Antígenos de Superfície/análise , Dendrímeros/química , Hepatite B/imunologia , Nanopartículas/química , Peptídeos/química , Sequência de Aminoácidos , Proteínas Ligantes de Maltose/metabolismo , Ligação Proteica , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura
12.
PeerJ ; 7: e7478, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31497388

RESUMO

Bacteria are present in stingless bee nest products. However, detailed information on their characteristics is scarce. Thus, this study aims to investigate the characteristics of bacterial species isolated from Malaysian stingless bee, Heterotrigona itama, nest products. Honey, bee bread and propolis were collected aseptically from four geographical localities of Malaysia. Total plate count (TPC), bacterial identification, phenotypic profile and enzymatic and antibacterial activities were studied. The results indicated that the number of TPC varies from one location to another. A total of 41 different bacterial isolates from the phyla Firmicutes, Proteobacteria and Actinobacteria were identified. Bacillus species were the major bacteria found. Therein, Bacillus cereus was the most frequently isolated species followed by Bacillus aryabhattai, Bacillus oleronius, Bacillus stratosphericus, Bacillus altitudinis, Bacillus amyloliquefaciens, Bacillus nealsonii, Bacillus toyonensis, Bacillus subtilis, Bacillus safensis, Bacillus pseudomycoides, Enterobacter asburiae, Enterobacter cloacae, Pantoea dispersa and Streptomyces kunmingensis. Phenotypic profile of 15 bacterial isolates using GEN III MicroPlate™ system revealed most of the isolates as capable to utilise carbohydrates as well as amino acids and carboxylic acids and derivatives. Proteolytic, lipolytic and cellulolytic activities as determined by enzymatic assays were detected in Bacillus stratosphericus PD6, Bacillus amyloliquefaciens PD9, Bacillus subtilis BD3 and Bacillus safensis BD9. Bacillus amyloliquefaciens PD9 showed broad-spectrum of antimicrobial activity against Gram-positive and Gram-negative bacteria in vitro. The multienzymes and antimicrobial activities exhibited by the bacterial isolates from H. itama nest products could provide potential sources of enzymes and antimicrobial compounds for biotechnological applications.

13.
Sci Rep ; 9(1): 13483, 2019 09 17.
Artigo em Inglês | MEDLINE | ID: mdl-31530893

RESUMO

The exponential escalation of dengue cases has indeed become a global health crisis. This work elaborates on the development of a biofunctionalized tapered optical fiber (TOF) based sensor with the integration of polyamidoamine (PAMAM) dendrimer for the detection of dengue E protein. The dimension of the TOF generated an evanescent field that was sensitive to any changes in the external medium while the integration of PAMAM promoted more adhesion of bio-recognition molecules; anti-DENV II E protein antibodies; that were complementary to the targeted protein. This in return created more active sites for the absorption of DENV II E proteins onto the tapered region. The resolution and detection limit of the sensor are 19.53 nm/nM and 1 pM, respectively with Kd = 1.02 × 10-10 M.


Assuntos
Técnicas Biossensoriais , Dendrímeros , Dengue/diagnóstico , Fibras Ópticas , Bioengenharia , Dengue/virologia , Vírus da Dengue , Feminino , Humanos , Masculino , Microscopia de Força Atômica , Análise Espectral Raman , Proteínas Virais/análise
14.
J Drug Target ; 27(3): 257-269, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-29911902

RESUMO

CD133 (prominin-1), a pentaspan membrane glycoprotein, is one of the most well-characterized biomarkers used for the isolation of cancer stem cells (CSCs). The presence of CSCs is one of the main causes of tumour reversal and resilience. Accumulating evidence has shown that CD133 might be responsible for CSCs tumourigenesis, metastasis and chemoresistance. It is now understood that CD133 interacts with the Wnt/ß-catenin and PI3K-Akt signalling pathways. Moreover, CD133 can upregulate the expression of the FLICE-like inhibitory protein (FLIP) in CD133-positive cells, inhibiting apoptosis. In addition, CD133 can increase angiogenesis by activating the Wnt signalling pathway and increasing the expression of vascular endothelial growth factor-A (VEGF-A) and interleukin-8. Therefore, CD133 could be considered to be an 'Achilles' heel' for CSCs, because by inhibiting this protein, the signalling pathways that are involved in cell proliferation will also be inhibited. By understanding the molecular biology of CD133, we can not only isolate stem cells but can also utilise it as a therapeutic strategy. In this review, we summarise new insights into the fundamental cell biology of CD133 and discuss the involvement of CD133 in metastasis, metabolism, tumourigenesis, drug-resistance, apoptosis and autophagy.


Assuntos
Antígeno AC133/metabolismo , Neoplasias/patologia , Células-Tronco Neoplásicas/metabolismo , Animais , Apoptose/fisiologia , Biomarcadores Tumorais/metabolismo , Proliferação de Células/fisiologia , Humanos , Transdução de Sinais/fisiologia
15.
Biochem Biophys Res Commun ; 503(2): 910-914, 2018 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-29928878

RESUMO

Ultraviolet (UV) radiation causes damage in all living organisms, including DNA damage that leads to cell death. Herein, we provide a new technique for UV radiation protection through intracellular short peptide expression. The late embryogenesis abundant (LEA) peptide, which functions as a shield that protects macromolecules from various abiotic stress, was obtained from the Polypedilum vanderplanki group 3 LEA protein. Recombinant Escherichia coli BL21 (DE3) expressing functional LEA short peptide in vivo were exposed to UVA and UVC radiation for 4, 6, and 8 h. E. coli transformants expressing the LEA peptide showed higher cell viability under both UVA and UVC treatment at all time points as compared with that of the control. Furthermore, the cells expressing LEA peptide showed a higher number of colony-forming units per dilution under UVA and UVC treatment. These results suggested that expression of the short peptide could be useful for the development of genetically modified organisms and in applications that require resilience of organisms to UV radiation.


Assuntos
Adaptação Fisiológica/efeitos da radiação , Escherichia coli/efeitos da radiação , Expressão Gênica , Proteínas de Insetos/genética , Peptídeos/genética , Raios Ultravioleta , Adaptação Fisiológica/genética , Animais , Chironomidae/genética , Escherichia coli/genética , Engenharia Genética/métodos , Viabilidade Microbiana/genética , Viabilidade Microbiana/efeitos da radiação , Transgenes/genética
16.
Appl Microbiol Biotechnol ; 102(9): 4131-4142, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29564523

RESUMO

Foot-and-mouth disease (FMD) is a major threat to the livestock industry worldwide. Despite constant surveillance and effective vaccination, the perpetual mutations of the foot-and-mouth disease virus (FMDV) pose a huge challenge to FMD diagnosis. The immunodominant region of the FMDV VP1 protein (residues 131-170) displayed on phage T7 has been used to detect anti-FMDV in bovine sera. In the present study, the functional epitope was further delineated using amino acid sequence alignment, homology modelling and phage display. Two highly conserved regions (VP1145-152 and VP1159-170) were identified among different FMDV serotypes. The coding regions of these two epitopes were fused separately to the T7 genome and displayed on the phage particles. Interestingly, chimeric phage displaying the VP1159-170 epitope demonstrated a higher antigenicity than that displaying the VP1131-170 epitope. By contrast, phage T7 displaying the VP1145-152 epitope did not react significantly with the anti-FMDV antibodies in vaccinated bovine sera. This study has successfully identified a smaller functional epitope, VP1159-170, located at the C-terminal end of the structural VP1 protein. The phage T7 displaying this shorter epitope is a promising diagnostic reagent to detect anti-FMDV antibodies in vaccinated animals.


Assuntos
Bacteriófago T7/metabolismo , Epitopos/metabolismo , Vírus da Febre Aftosa/metabolismo , Animais , Anticorpos Antivirais/sangue , Anticorpos Antivirais/metabolismo , Bacteriófago T7/genética , Proteínas do Capsídeo/genética , Bovinos , Epitopos/genética , Febre Aftosa/diagnóstico
17.
Protein Pept Lett ; 25(1): 90-95, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29237368

RESUMO

BACKGROUND: Mercury (II) ion, Hg2+ is among the most common pollutants with the ability to affect the environment. The implications of their elevation in the environment are mainly due to the industrialization and urbanization process. Current methods of Hg2+ detection primarily depend on sophisticated and expensive instruments. Hence, an alternative and practical way of detecting Hg2+ ions is needed to go beyond these limitations. Here, we report a detection method that was developed using an inhibitive enzymatic reaction that can be monitored through a smartphone. Horseradish peroxidase (HRP) converted 4-aminoantipyrene (4-AAP) into a red colored product which visible with naked eye. A colorless product, on the other hand, was produced indicating the presence of Hg2+ that inhibit the reaction. OBJECTIVES: The aim of this study is to develop a colorimetric sensor to detect Hg2+ in water sources using HRP inhibitive assay. The system can be incorporated with a mobile app to make it practical for a prompt in-situ analysis. METHODS: HRP enzyme was pre-incubated with different concentration of Hg2+ at 37°C for 1 hour prior to the addition of chromogen. The mix of PBS buffer, 4-AAP and phenol which act as a chromogen was then added to the HRP enzyme and was incubated for 20 minutes. Alcohol was added to stop the enzymatic reaction, and the change of colour were observed and analyse using UV-Vis spectrophotometer at 520 nm wavelength. The results were then analysed using GraphPad PRISM 4 for a non-linear regression analysis, and using Mathematica (Wolfram) 10.0 software for a hierarchical cluster analysis. The samples from spectroscopy measurement were directly used for dynamic light scattering (DLS) evaluation to evaluate the changes in HRP size due to Hg2+ malfunctionation. Finally, molecular dynamic simulations comparing normal and malfunctioned HRP were carried out to investigate structural changes of the HRP using YASARA software. RESULTS: Naked eye detection and data from UV-Vis spectroscopy showed good selectivity of Hg2+ over other metal ions as a distinctive color of Hg2+ is observed at 0.5 ppm with the IC50 of 0.290 ppm. The mechanism of Hg2+ inhibition towards HRP was further validated using a dynamic light scattering (DLS) and molecular dynamics (MD) simulation to ensure that there is a conformational change in HRP size due to the presence of Hg2+ ions. The naked eye detection can be quantitatively determined using a smartphone app namely ColorAssist, suggesting that the detection signal does not require expensive instruments to be quantified. CONCLUSION: A naked-eye colorimetric sensor for mercury ions detection was developed. The colour change due to the presence of Hg2+ can be easily distinguished using an app via a smartphone. Thus, without resorting to any expensive instruments that are mostly laboratory bound, Hg2+ can be easily detected at IC50 value of 0.29 ppm. This is a promising alternative and practical method to detect Hg2+ in the environment.


Assuntos
Bioensaio/métodos , Peroxidase do Rábano Silvestre/química , Mercúrio/análise , Smartphone , Poluentes Químicos da Água/análise , Calibragem , Cátions Bivalentes/análise , Colorimetria , Corantes/química , Difusão Dinâmica da Luz , Luz , Limite de Detecção , Simulação de Dinâmica Molecular , Oxirredução , Tamanho da Partícula , Espectrofotometria Ultravioleta
18.
Protein Pept Lett ; 25(1): 34-41, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29237369

RESUMO

BACKGROUND: Direct bio-monitoring essentially involves optical means since photon has insignificant effects over biomolecules. Over the years, laser induced surface Plasmon resonance method with various modifications as well as versatile localized Plasmon excited by incoherent light have facilitated in recording many nanobiological activities. Yet, monitoring interactions of small molecules including drugs requires signal amplification and improvement on signal-to-noise ratio. OBJECTIVES: This paper focused on how the refractive index based nanobio-sensoring gold platform can produce more efficient, adaptable and more practical detection techniques to observe molecular interactions at high degree of sensitivity. It discusses surface chemistry approach, optimisation of the refractive index of gold platform and manipulation of gold geometry augmenting signal quality. METHODS: In a normal-incidence reflectivity, r0 can be calculated using the Fresnel equation. Particularly at λ = 470 nm the ratio of r / r0 showed significant amplitude reduction mainly stemmed from the imaginary part of the Au refractive index. Hence, the fraction of reduction, Δr = 1 - r / r0. Experimentally, in a common reference frame reflectivity of a bare gold surface, R0 is compared with the reflectivity of gold surface in the presence of biolayer, R. The reduction rate (%) of reflectivity, ΔR = 1 - R / R0 is denoted as the AR signal. The method therefore enables quantitative measurement of the surface-bound protein by converting ΔR to the thickness, d, and subsequently the protein mass. We discussed four strategies to improve the AR signal by changing the effective refractive index of the biosensing platform. They are; a) Thickness optimisation of Au thin layer, b) Au / Ag bimetallic layer, c) composing alloy or Au composite, and d) Au thinlayer with nano or micro holes. RESULTS: As the result we successfully 'move' the refractive index, ε of the AR platform (gold only) to ε = -0.948 + 3.455i, a higher sensitivity platform. This was done by composing Au-Ag2O composite with ratio = 1:1. The results were compared to the potential sensitivity improvement of the AR substrate using other that could be done by further tailoring the ε advanced method. CONCLUSION: We suggested four strategies in order to realize this purpose. It is apparent that sensitivity has been improved through Au/Ag bimetallic layer or Au-Ag2O composite thin layer, This study is an important step towards fabrication of sensitive surface for detection of biomolecular interactions.


Assuntos
Ouro/química , Nanoestruturas/química , Proteínas/análise , Refratometria/métodos , Ressonância de Plasmônio de Superfície/métodos , Técnicas Biossensoriais , Luz , Limite de Detecção , Óxidos/química , Compostos de Prata/química , Propriedades de Superfície
19.
Artigo em Inglês | MEDLINE | ID: mdl-30643535

RESUMO

Heterotrigona itama is a common stingless bee species found in Southeast Asia. Studies on the health benefits of its honey are limited in comparison with other stingless bee species. This study examines the antiobesity benefits found in stingless bee honey (SBH) from H. itama. The parameters used to measure the benefits were weight change, morphological structures, and biochemical characteristics. The research was conducted by using rats that were given a high-fat diet (HFD). In total 48 male Sprague Dawley (SD) rats were given a formulated HFD to increase the levels of obesity, the HFD was administered with a value of 0.68 g/cm2. The duration of the treatment was six weeks, and the results show that the induction obesity using the HFD was successful. Following this, the rats were then treated with SBH (at dosages of 1000 mg/kg, 750 mg/kg or 500 mg/kg), with orlistat or with a placebo. Compared with typical obesity treatment methods, the one that used the three dosages of SBH showed a higher reduction in body mass index (BMI), percentage of body weight gain, adiposity index, and relative organ weight (ROW). The levels of liver enzymes (ALT, AST, and ALP) were also significantly lower in SBH-treated groups. The levels of triglycerides and LDL-cholesterol were significantly lower, while the level of HDL-cholesterol was significantly higher in comparison with the control obese group. In terms of morphological structures, the number of adipocyte cells was reduced, and the hepatocytes found in the liver were less prone to rupturing when treated with SBH. In conclusion, the administration of SBH led to an improvement in indicators associated with obesity reduction. SBH also possesses a hepatoprotective potential which can reduce the health risks related to obesity.

20.
Methods Mol Biol ; 1352: 97-110, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26490470

RESUMO

The importance of protein detection system for protein functions analyses in recent post-genomic era is rising with the emergence of label-free protein detection methods. We are focusing on a simple and practical label-free optical-detection method called anomalous reflection (AR) of gold. When a molecular layer forms on the gold surface, significant reduction in reflectivity can be observed at wavelengths of 400-500 nm. This allows the detection of molecular interactions by monitoring changes in reflectivity. In this chapter, we describe the AR method with three different application platforms: (1) gold, (2) gold containing alloy/composite (AuAg2O), and (3) metal-insulator-metal (MIM) thin layers. The AuAg2O composite and MIM are implemented as important concepts for signal enhancement process for the AR technique. Moreover, the observed molecular adsorption and activity is aided by a three-dimensional surface geometry, performed using poly(amidoamine) or PAMAM dendrimer modification. The described system is suitable to be used as a platform for high-throughput detection system in a chip format.


Assuntos
Ouro , Procedimentos Analíticos em Microchip/métodos , Fenômenos Ópticos , Dendrímeros/química , Ouro/química , Óxidos/química , Compostos de Prata/química , Propriedades de Superfície
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