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A simulation study on the radiosensitization properties of gold nanorods

Taheri A, Khandaker MU, Moradi F, Bradley DA

Phys Med Biol, 2024 Feb 15;69(4).
PMID: 38286017 DOI: 10.1088/1361-6560/ad2380

Objective. Gold nanorods (GNRs) have emerged as versatile nanoparticles with unique properties, holding promise in various modalities of cancer treatment through drug delivery and photothermal therapy. In the rapidly evolving field of nanoparticle radiosensitization (NPRS) for cancer therapy, this study assessed the potential of gold nanorods as radiosensitizing agents by quantifying the key features of NPRS, such as secondary electron emission and dose enhancement, using Monte Carlo simulations.Approach. Employing the TOPAS track structure code, we conducted a comprehensive evaluation of the radiosensitization behavior of spherical gold nanoparticles and gold nanorods. We systematically explored the impact of nanorod geometry (in particular size and aspect ratio) and orientation on secondary electron emission and deposited energy ratio, providing validated results against previously published simulations.Main results. Our findings demonstrate that gold nanorods exhibit comparable secondary electron emission to their spherical counterparts. Notably, nanorods with smaller surface-area-to-volume ratios (SA:V) and alignment with the incident photon beam proved to be more efficient radiosensitizing agents, showing superiority in emitted electron fluence. However, in the microscale, the deposited energy ratio (DER) was not markedly influenced by the SA:V of the nanorod. Additionally, our findings revealed that the geometry of gold nanoparticles has a more significant impact on the emission of M-shell Auger electrons (with energies below 3.5 keV) than on higher-energy electrons.Significance. This research investigated the radiosensitization properties of gold nanorods, positioning them as promising alternatives to the more conventionally studied spherical gold nanoparticles in the context of cancer research. With increasing interest in multimodal cancer therapy, our findings have the potential to contribute valuable insights into the perspective of gold nanorods as effective multipurpose agents for synergistic photothermal therapy and radiotherapy. Future directions may involve exploring alternative metallic nanorods as well as further optimizing the geometry and coating materials, opening new possibilities for more effective cancer treatments.

Matched MeSH terms: Gold/chemistry
Fulltext Thickness Dependent Nanostructural, Morphological, Optical and Impedometric Analyses of Zinc Oxide-Gold Hybrids: Nanoparticle to Thin Film

Perumal V, Hashim U, Gopinath SC, Haarindraprasad R, Liu WW, Poopalan P, et al.

PLoS One, 2015;10(12):e0144964.
PMID: 26694656 DOI: 10.1371/journal.pone.0144964

The creation of an appropriate thin film is important for the development of novel sensing surfaces, which will ultimately enhance the properties and output of high-performance sensors. In this study, we have fabricated and characterized zinc oxide (ZnO) thin films on silicon substrates, which were hybridized with gold nanoparticles (AuNPs) to obtain ZnO-Aux (x = 10, 20, 30, 40 and 50 nm) hybrid structures with different thicknesses. Nanoscale imaging by field emission scanning electron microscopy revealed increasing film uniformity and coverage with the Au deposition thickness. Transmission electron microscopy analysis indicated that the AuNPs exhibit an increasing average diameter (5-10 nm). The face center cubic Au were found to co-exist with wurtzite ZnO nanostructure. Atomic force microscopy observations revealed that as the Au content increased, the overall crystallite size increased, which was supported by X-ray diffraction measurements. The structural characterizations indicated that the Au on the ZnO crystal lattice exists without any impurities in a preferred orientation (002). When the ZnO thickness increased from 10 to 40 nm, transmittance and an optical bandgap value decreased. Interestingly, with 50 nm thickness, the band gap value was increased, which might be due to the Burstein-Moss effect. Photoluminescence studies revealed that the overall structural defect (green emission) improved significantly as the Au deposition increased. The impedance measurements shows a decreasing value of impedance arc with increasing Au thicknesses (0 to 40 nm). In contrast, the 50 nm AuNP impedance arc shows an increased value compared to lower sputtering thicknesses, which indicated the presence of larger sized AuNPs that form a continuous film, and its ohmic characteristics changed to rectifying characteristics. This improved hybrid thin film (ZnO/Au) is suitable for a wide range of sensing applications.

Matched MeSH terms: Gold/chemistry*
Fulltext Fabrication of an electrochemical sensor based on gold nanoparticles/carbon nanotubes as nanocomposite materials: determination of myricetin in some drinks

Hajian R, Yusof NA, Faragi T, Shams N

PLoS One, 2014;9(5):e96686.
PMID: 24809346 DOI: 10.1371/journal.pone.0096686

In this paper, the electrochemical behavior of myricetin on a gold nanoparticle/ethylenediamine/multi-walled carbon-nanotube modified glassy carbon electrode (AuNPs/en/MWCNTs/GCE) has been investigated. Myricetin effectively accumulated on the AuNPs/en/MWCNTs/GCE and caused a pair of irreversible redox peaks at around 0.408 V and 0.191 V (vs. Ag/AgCl) in 0.1 mol L-1 phosphate buffer solution (pH 3.5) for oxidation and reduction reactions respectively. The heights of the redox peaks were significantly higher on AuNPs/en/MWNTs/GCE compare with MWCNTs/GC and there was no peak on bare GC. The electron-transfer reaction for myricetin on the surface of electrochemical sensor was controlled by adsorption. Some parameters including pH, accumulation potential, accumulation time and scan rate have been optimized. Under the optimum conditions, anodic peak current was proportional to myricetin concentration in the dynamic range of 5.0×10-8 to 4.0×10-5 mol L-1 with the detection limit of 1.2×10-8 mol L-1. The proposed method was successfully used for the determination of myricetin content in tea and fruit juices.

Matched MeSH terms: Gold/chemistry*
Fulltext Electronic Characterization of Au/DNA/ITO Metal-Semiconductor-Metal Diode and Its Application as a Radiation Sensor

Al-Ta'ii HM, Periasamy V, Amin YM

PLoS One, 2016;11(1):e0145423.
PMID: 26799703 DOI: 10.1371/journal.pone.0145423

Deoxyribonucleic acid or DNA molecules expressed as double-stranded (DSS) negatively charged polymer plays a significant role in electronic states of metal/silicon semiconductor structures. Electrical parameters of an Au/DNA/ITO device prepared using self-assembly method was studied by using current-voltage (I-V) characteristic measurements under alpha bombardment at room temperature. The results were analyzed using conventional thermionic emission model, Cheung and Cheung's method and Norde's technique to estimate the barrier height, ideality factor, series resistance and Richardson constant of the Au/DNA/ITO structure. Besides demonstrating a strongly rectifying (diode) characteristic, it was also observed that orderly fluctuations occur in various electrical parameters of the Schottky structure. Increasing alpha radiation effectively influences the series resistance, while the barrier height, ideality factor and interface state density parameters respond linearly. Barrier height determined from I-V measurements were calculated at 0.7284 eV for non-radiated, increasing to about 0.7883 eV in 0.036 Gy showing an increase for all doses. We also demonstrate the hypersensitivity phenomena effect by studying the relationship between the series resistance for the three methods, the ideality factor and low-dose radiation. Based on the results, sensitive alpha particle detectors can be realized using Au/DNA/ITO Schottky junction sensor.

Matched MeSH terms: Gold/chemistry*
Fulltext Safety and Efficacy of Human Wharton's Jelly-Derived Mesenchymal Stem Cells Therapy for Retinal Degeneration

Leow SN, Luu CD, Hairul Nizam MH, Mok PL, Ruhaslizan R, Wong HS, et al.

PLoS One, 2015;10(6):e0128973.
PMID: 26107378 DOI: 10.1371/journal.pone.0128973

To investigate the safety and efficacy of subretinal injection of human Wharton's Jelly-derived mesenchymal stem cells (hWJ-MSCs) on retinal structure and function in Royal College of Surgeons (RCS) rats.

Matched MeSH terms: Gold/chemistry
Fulltext Synthesis, spectral characterization and crystals structure of some arsane derivatives of gold (I) complexes: a comparative density functional theory study

Shawkataly OB, Goh CP, Tariq A, Khan IA, Fun HK, Rosli MM

PLoS One, 2015;10(3):e0119620.
PMID: 25798915 DOI: 10.1371/journal.pone.0119620

A series of complexes of the type LAuCl where L = tris(p-tolylarsane), tris(m-tolylarsane), bis(diphenylarsano)ethane, and tris(naphthyl)arsane have been synthesized. All of the new complexes, 1-4, have been fully characterized by means of ¹H NMR and ¹³C NMR spectroscopy and single crystal X-ray crystallography. The structures of complexes 1-4 have been determined from X-ray diffraction data. The linear molecules have an average bond distance between gold-arsenic and gold-chlorine of 2.3390Å and 2.2846Å, respectively. Aurophilic interaction was prominent in complex 1 and 3, whereas complex 2 and 4 do not show any such interaction. The intermolecular gold interaction bond length was affected by the electronegativity of the molecule. The computed values calculated at DFT level using B3LYP function are in good agreement with the experimental results.

Matched MeSH terms: Gold/chemistry*
Fulltext Hybrid nanocomposite curcumin-capped gold nanoparticle-reduced graphene oxide: Anti-oxidant potency and selective cancer cytotoxicity

Al-Ani LA, Yehye WA, Kadir FA, Hashim NM, AlSaadi MA, Julkapli NM, et al.

PLoS One, 2019;14(5):e0216725.
PMID: 31086406 DOI: 10.1371/journal.pone.0216725

Nanotechnology-based antioxidants and therapeutic agents are believed to be the next generation tools to face the ever-increasing cancer mortality rates. Graphene stands as a preferred nano-therapeutic template, due to the advanced properties and cellular interaction mechanisms. Nevertheless, majority of graphene-based composites suffer from hindered development as efficient cancer therapeutics. Recent nano-toxicology reviews and recommendations emphasize on the preliminary synthetic stages as a crucial element in driving successful applications results. In this study, we present an integrated, green, one-pot hybridization of target-suited raw materials into curcumin-capped gold nanoparticle-conjugated reduced graphene oxide (CAG) nanocomposite, as a prominent anti-oxidant and anti-cancer agent. Distinct from previous studies, the beneficial attributes of curcumin are employed to their fullest extent, such that they perform dual roles of being a natural reducing agent and possessing antioxidant anti-cancer functional moiety. The proposed novel green synthesis approach secured an enhanced structure with dispersed homogenous AuNPs (15.62 ± 4.04 nm) anchored on reduced graphene oxide (rGO) sheets, as evidenced by transmission electron microscopy, surpassing other traditional chemical reductants. On the other hand, safe, non-toxic CAG elevates biological activity and supports biocompatibility. Free radical DPPH inhibition assay revealed CAG antioxidant potential with IC50 (324.1 ± 1.8%) value reduced by half compared to that of traditional citrate-rGO-AuNP nanocomposite (612.1 ± 10.1%), which confirms the amplified multi-potent antioxidant activity. Human colon cancer cell lines (HT-29 and SW-948) showed concentration- and time-dependent cytotoxicity for CAG, as determined by optical microscopy images and WST-8 assay, with relatively low IC50 values (~100 μg/ml), while preserving biocompatibility towards normal human colon (CCD-841) and liver cells (WRL-68), with high selectivity indices (≥ 2.0) at all tested time points. Collectively, our results demonstrate effective green synthesis of CAG nanocomposite, free of additional stabilizing agents, and its bioactivity as an antioxidant and selective anti-colon cancer agent.

Matched MeSH terms: Gold/chemistry*
Fulltext A bimodal theranostic nanodelivery system based on [graphene oxide-chlorogenic acid-gadolinium/gold] nanoparticles

Usman MS, Hussein MZ, Fakurazi S, Masarudin MJ, Ahmad Saad FF

PLoS One, 2018;13(7):e0200760.
PMID: 30044841 DOI: 10.1371/journal.pone.0200760

We have synthesized a bimodal theranostic nanodelivery system (BIT) that is based on graphene oxide (GO) and composed of a natural chemotherapeutic agent, chlorogenic acid (CA) used as the anticancer agent, while gadolinium (Gd) and gold nanoparticles (AuNPs) were used as contrast agents for magnetic resonance imaging (MRI) modality. The CA and Gd guest agents were simultaneously loaded on the GO nanolayers using chemical interactions, such as hydrogen bonding and π-π non-covalent interactions to form GOGCA nanocomposite. Subsequently, the AuNPs were doped on the surface of the GOGCA by means of electrostatic interactions, which resulted in the BIT. The physico-chemical studies of the BIT affirmed its successful development. The X-ray diffractograms (XRD) collected of the various stages of BIT synthesis showed the successive development of the hybrid system, while 90% of the chlorogenic acid was released in phosphate buffer solution (PBS) at pH 4.8. This was further reaffirmed by the in vitro evaluations, which showed stunted HepG2 cancer cells growth against the above 90% cell growth in the control cells. A reverse case was recorded for the 3T3 normal cells. Further, the acquired T1-weighted image of the BIT doped samples obtained from the MRI indicated contrast enhancement in comparison with the plain Gd and water references. The abovementioned results portray our BIT as a promising future chemotherapeutic for anticancer treatment with diagnostic modalities.

Matched MeSH terms: Gold/chemistry
Signal Enhancement Strategies for Refractive Index-Sensitive Nanobiosensor

Syahir A, Kajikawa K, Mihara H

Protein Pept Lett, 2018;25(1):34-41.
PMID: 29237369 DOI: 10.2174/0929866525666171214111957

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.

Matched MeSH terms: Gold/chemistry*
Fulltext 'Spotted Nanoflowers': Gold-seeded Zinc Oxide Nanohybrid for Selective Bio-capture

Perumal V, Hashim U, Gopinath SC, Haarindraprasad R, Foo KL, Balakrishnan SR, et al.

Sci Rep, 2015 Jul 16;5:12231.
PMID: 26178973 DOI: 10.1038/srep12231

Hybrid gold nanostructures seeded into nanotextured zinc oxide (ZnO) nanoflowers (NFs) were created for novel biosensing applications. The selected 'spotted NFs' had a 30-nm-thick gold nanoparticle (AuNP) layer, chosen from a range of AuNP thicknesses, sputtered onto the surface. The generated nanohybrids, characterized by morphological, physical and structural analyses, were uniformly AuNP-seeded onto the ZnO NFs with an average length of 2-3 μm. Selective capture of molecular probes onto the seeded AuNPs was evidence for the specific interaction with DNA from pathogenic Leptospirosis-causing strains via hybridization and mis-match analyses. The attained detection limit was 100 fM as determined via impedance spectroscopy. High levels of stability, reproducibility and regeneration of the sensor were obtained. Selective DNA immobilization and hybridization were confirmed by nitrogen and phosphorus peaks in an X-ray photoelectron spectroscopy analysis. The created nanostructure hybrids illuminate the mechanism of generating multiple-target, high-performance detection on a single NF platform, which opens a new avenue for array-based medical diagnostics.

Matched MeSH terms: Gold/chemistry*
Fulltext Effect of Hybrid mono/bimetallic Nanocomposites for an enhancement of Catalytic and Antimicrobial Activities

Sivaranjan K, Padmaraj O, Santhanalakshmi J, Sathuvan M, Sathiyaseelan A, Sagadevan S

Sci Rep, 2020 02 13;10(1):2586.
PMID: 32054936 DOI: 10.1038/s41598-020-59491-5

Exploring the new catalytic systems for the reduction of organic and inorganic pollutants from an indispensable process in chemical, petrochemical, pharmaceutical and food industries, etc. Hence, in the present work, authors motivated to synthesize bare reduced graphene oxide (rGO), polyaniline (PANI), three different ratios of rGO-PANI(80:20,50:50, 10:90) composites and rGO-PANI(80:20,50:50, 10:90) supported mono (Pd) & bimetallic [Pd: Au(1:1,1:2, 2:1)] nanocomposite by a facile chemical reduction method. Also, it investigated their catalytic performances for the reduction of organic/inorganic pollutants and antimicrobial activities. All the freshly prepared bare rGO, PANI, three different ratios of rGO-PANI(80:20, 50:50,10:90) composites and rGO-PANI(80:20, 50:50,10:90)/Pd & Pd: Au(1:1, 1:2,2:1) nanocomposite hybrid catalysts were characterized using UV-Vis, FT-IR, SEM, FE-SEM, EDAX, HR-TEM, XRD, XPS and Raman spectroscopy analysis. Among them, an optimized best composition of rGO-PANI(80:20)/Pd: Au(1:1) bimetallic nanocomposite hybrid catalyst exhibits better catalytic reduction and antimicrobial activities than other composites, as a result of strong electrostatic interactions between rGO, PANI and bimetal (Pd: Au) NPs through a synergistic effect. Hence, an optimized rGO-PANI(80:20)/Pd:Au(1:1) bimetallic nanocomposite catalyst would be considered as a suitable catalyst for the reduction of different nitroarenes, organic dyes, heavy metal ions and also significantly inhibit the growth of S. aureus, S. Typhi as well as Candida albicans and Candida kruesi in wastewater.

Matched MeSH terms: Gold/chemistry*
Fulltext Fabrication and Characterization of Glucose Biosensors by Using Hydrothermally Grown ZnO Nanorods

Ridhuan NS, Abdul Razak K, Lockman Z

Sci Rep, 2018 09 13;8(1):13722.
PMID: 30213995 DOI: 10.1038/s41598-018-32127-5

Highly oriented ZnO nanorod (NR) arrays were fabricated on a seeded substrate through a hydrothermal route. The prepared ZnO nanorods were used as an amperometric enzyme electrode, in which glucose oxidase (GOx) was immobilised through physical adsorption. The modified electrode was designated as Nafion/GOx/ZnO NRs/ITO. The morphology and structural properties of the fabricated ZnO nanorods were analysed using field-emission scanning electron microscope and X-ray diffractometer. The electrochemical properties of the fabricated biosensor were studied by cyclic voltammetry and amperometry. Electrolyte pH, electrolyte temperature and enzyme concentration used for immobilisation were the examined parameters influencing enzyme activity and biosensor performance. The immobilised enzyme electrode showed good GOx retention activity. The amount of electroactive GOx was 7.82 × 10-8 mol/cm2, which was relatively higher than previously reported values. The Nafion/GOx/ZnO NRs/ITO electrode also displayed a linear response to glucose ranging from 0.05 mM to 1 mM, with a sensitivity of 48.75 µA/mM and a low Michaelis-Menten constant of 0.34 mM. Thus, the modified electrode can be used as a highly sensitive third-generation glucose biosensor with high resistance against interfering species, such as ascorbic acid, uric acid and L-cysteine. The applicability of the modified electrode was tested using human blood samples. Results were comparable with those obtained using a standard glucometer, indicating the excellent performance of the modified electrode.

Matched MeSH terms: Gold/chemistry
Fulltext Temperature and magnetic field driven modifications in the I-V features of gold-DNA-gold structure I-V

Khatir NM, Abdul-Malek Z, Banihashemian SM

Sensors (Basel), 2014;14(10):19229-41.
PMID: 25320908 DOI: 10.3390/s141019229

The fabrication of Metal-DNA-Metal (MDM) structure-based high sensitivity sensors from DNA micro-and nanoarray strands is a key issue in their development. The tunable semiconducting response of DNA in the presence of external electromagnetic and thermal fields is a gift for molecular electronics. The impact of temperatures (25-55 °C) and magnetic fields (0-1200 mT) on the current-voltage (I-V) features of Au-DNA-Au (GDG) structures with an optimum gap of 10 μm is reported. The I-V characteristics acquired in the presence and absence of magnetic fields demonstrated the semiconducting diode nature of DNA in GDG structures with high temperature sensitivity. The saturation current in the absence of magnetic field was found to increase sharply with the increase of temperature up to 45 °C and decrease rapidly thereafter. This increase was attributed to the temperature-assisted conversion of double bonds into single bond in DNA structures. Furthermore, the potential barrier height and Richardson constant for all the structures increased steadily with the increase of external magnetic field irrespective of temperature variations. Our observation on magnetic field and temperature sensitivity of I-V response in GDG sandwiches may contribute towards the development of DNA-based magnetic sensors.

Matched MeSH terms: Gold/chemistry
Fulltext Detection of formaldehyde in water: a shape-effect on the plasmonic sensing properties of the gold nanoparticles

Nengsih S, Umar AA, Salleh MM, Oyama M

Sensors (Basel), 2012;12(8):10309-25.
PMID: 23112601 DOI: 10.3390/s120810309

The effect of morphology on the plasmonic sensing of the presence of formaldehyde in water by gold nanostructures has been investigated. The gold nanostructures with two different morphologies, namely spherical and rod, were prepared using a seed-mediated method. In typical results, it was found that the plasmonic properties of gold nanostructures were very sensitive to the presence of formaldehyde in their surrounding medium by showing the change in both the plasmonic peaks position and the intensity. Spherical nanoparticles (GNS), for example, indicated an increase in the sensitivity when the size was increased from 25 to 35 nm and dramatically decreased when the size was further increased. An m value, the ratio between plasmonic peak shift and refractive index change, as high as 36.5 nm/RIU (refractive index unit) was obtained so far. An expanded sensing mode to FD was obtained when gold nanostructures with nanorods morphology (GNR) were used because of the presence of two plasmonic modes for response probing. However, in the present study, effective plasmonic peak shift was not observed due to the intense plasmonic coupling of closely packed nanorod structures on the surface. Nevertheless, the present results at least provide a potential strategy for response enhancement via shape-effects. High performance plasmonic sensors could be obtained if controlled arrays of nanorods can be prepared on the surface.

Matched MeSH terms: Gold/chemistry*
Fulltext Immuno Nanosensor for the Ultrasensitive Naked Eye Detection of Tuberculosis

Mohd Bakhori N, Yusof NA, Abdullah J, Wasoh H, Md Noor SS, Ahmad Raston NH, et al.

Sensors (Basel), 2018 Jun 14;18(6).
PMID: 29899214 DOI: 10.3390/s18061932

In the present study, a beneficial approach for the ultrasensitive and affordable naked eye detection and diagnosis of tuberculosis (TB) by utilizing plasmonic enzyme-linked immunosorbent assay (ELISA) via antibody-antigen interaction was studied. Here, the biocatalytic cycle of the intracellular enzymes links to the formation and successive growth of the gold nanoparticles (GNPs) for ultrasensitive detection. The formation of different colored solutions by the plasmonic nanoparticles in the presence of enzyme labels links directly to the existence or non-existence of the TB analytes in the sample solutions. For disease detection, the adapted protocol is based mainly on the conventional ELISA procedure that involves catalase-labeled antibodies, i.e., the enzymes consume hydrogen peroxide and further produce GNPs with the addition of gold (III) chloride. The amount of hydrogen peroxide remaining in the solution determines whether the GNPs solution is to be formed in the color blue or the color red, as it serves as a confirmation for the naked eye detection of TB analytes. However, the conventional ELISA method only shows tonal colors that need a high concentration of analyte to achieve high confidence levels for naked eye detection. Also, in this research, we proposed the incorporation of protein biomarker, Mycobacterium tuberculosis ESAT-6-like protein esxB (CFP-10), as a means of TB detection using plasmonic ELISA. With the use of this technique, the CFP-10 detection limit can be lowered to 0.01 µg/mL by the naked eye. Further, our developed technique was successfully tested and confirmed with sputum samples from patients diagnosed with positive TB, thereby providing enough evidence for the utilization of our technique in the early diagnosis of TB disease.

Matched MeSH terms: Gold/chemistry
Fulltext Patterned Array of Poly(ethylene glycol) Silane Monolayer for Label-Free Detection of Dengue

Rosly NZ, Ahmad SA, Abdullah J, Yusof NA

Sensors (Basel), 2016 Aug 25;16(9).
PMID: 27571080 DOI: 10.3390/s16091365

In the present study, the construction of arrays on silicon for naked-eye detection of DNA dengue was demonstrated. The array was created by exposing a polyethylene glycol (PEG) silane monolayer to 254 nm ultraviolet (UV) light through a photomask. Formation of the PEG silane monolayer and photomodifed surface properties was thoroughly characterized by using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. The results of XPS confirmed that irradiation of ultraviolet (UV) light generates an aldehyde functional group that offers conjugation sites of amino DNA probe for detection of a specific dengue virus target DNA. Employing a gold enhancement process after inducing the electrostatic interaction between positively charged gold nanoparticles and the negatively charged target DNA hybridized to the DNA capture probe allowed to visualize the array with naked eye. The developed arrays demonstrated excellent performance in diagnosis of dengue with a detection limit as low as 10 pM. The selectivity of DNA arrays was also examined using a single base mismatch and noncomplementary target DNA.

Matched MeSH terms: Gold/chemistry
Fulltext An Electrochemical DNA Biosensor for Carcinogenicity of Anticancer Compounds Based on Competition between Methylene Blue and Oligonucleotides

Md Sani ND, Ariffin EY, Sheryn W, Shamsuddin MA, Heng LY, Latip J, et al.

Sensors (Basel), 2019 Nov 22;19(23).
PMID: 31766637 DOI: 10.3390/s19235111

A toxicity electrochemical DNA biosensor has been constructed for the detection of carcinogens using 24 base guanine DNA rich single stranded DNA, and methylene blue (MB) as the electroactive indicator. This amine terminated ssDNA was immobilized onto silica nanospheres and deposited on gold nanoparticle modified carbon-paste screen printed electrodes (SPEs). The modified SPE was initially exposed to a carcinogen, followed by immersion in methylene blue for an optimized duration. The biosensor response was measured using differential pulse voltammetry. The performance of the biosensor was identified on several anti-cancer compounds. The toxicity DNA biosensor demonstrated a linear response range to the cadmium chloride from 0.0005 ppm to 0.01 ppm (R2 = 0.928) with a limit of detection at 0.0004 ppm. The biosensor also exhibited its versatility to screen the carcinogenicity of potential anti-cancer compounds.

Matched MeSH terms: Gold/chemistry
Fulltext Sandwich-Type DNA Micro-Optode Based on Gold-Latex Spheres Label for Reflectance Dengue Virus Detection

Jeningsih, Tan LL, Ulianas A, Heng LY, Mazlan NF, Jamaluddin ND, et al.

Sensors (Basel), 2020 Mar 25;20(7).
PMID: 32218202 DOI: 10.3390/s20071820

A DNA micro-optode for dengue virus detection was developed based on the sandwich hybridization strategy of DNAs on succinimide-functionalized poly(n-butyl acrylate) (poly(nBA-NAS)) microspheres. Gold nanoparticles (AuNPs) with an average diameter of ~20 nm were synthesized using a centrifugation-based method and adsorbed on the submicrometer-sized polyelectrolyte-coated poly(styrene-co-acrylic acid) (PSA) latex particles via an electrostatic method. The AuNP-latex spheres were attached to the thiolated reporter probe (rDNA) by Au-thiol binding to functionalize as an optical gold-latex-rDNA label. The one-step sandwich hybridization recognition involved a pair of a DNA probe, i.e., capture probe (pDNA), and AuNP-PSA reporter label that flanked the target DNA (complementary DNA (cDNA)). The concentration of dengue virus cDNA was optically transduced by immobilized AuNP-PSA-rDNA conjugates as the DNA micro-optode exhibited a violet hue upon the DNA sandwich hybridization reaction, which could be monitored by a fiber-optic reflectance spectrophotometer at 637 nm. The optical genosensor showed a linear reflectance response over a wide cDNA concentration range from 1.0 × 10-21 M to 1.0 × 10-12 M cDNA (R2 = 0.9807) with a limit of detection (LOD) of 1 × 10-29 M. The DNA biosensor was reusable for three consecutive applications after regeneration with mild sodium hydroxide. The sandwich-type optical biosensor was well validated with a molecular reverse transcription polymerase chain reaction (RT-PCR) technique for screening of dengue virus in clinical samples, e.g., serum, urine, and saliva from dengue virus-infected patients under informed consent.

Matched MeSH terms: Gold/chemistry
Fulltext Construction of an Electrochemical Sensor Based on Carbon Nanotubes/Gold Nanoparticles for Trace Determination of Amoxicillin in Bovine Milk

Muhammad A, Yusof NA, Hajian R, Abdullah J

Sensors (Basel), 2016;16(1).
PMID: 26805829 DOI: 10.3390/s16010056

In this work, a novel electrochemical sensor was fabricated for determination of amoxicillin in bovine milk samples by decoration of carboxylated multi-walled carbon nanotubes (MWCNTs) with gold nanoparticles (AuNPs) using ethylenediamine (en) as a cross linker (AuNPs/en-MWCNTs). The constructed nanocomposite was homogenized in dimethylformamide and drop casted on screen printed electrode. Field emission scanning electron microscopy (FESEM), energy dispersive X-Ray (EDX), X-Ray diffraction (XRD) and cyclic voltammetry were used to characterize the synthesized nanocomposites. The results show that the synthesized nanocomposites induced a remarkable synergetic effect for the oxidation of amoxicillin. Effect of some parameters, including pH, buffer, scan rate, accumulation potential, accumulation time and amount of casted nanocomposites, on the sensitivity of fabricated sensor were optimized. Under the optimum conditions, there was two linear calibration ranges from 0.2-10 µM and 10-30 µM with equations of Ipa (µA) = 2.88C (µM) + 1.2017; r = 0.9939 and Ipa (µA) = 0.88C (µM) + 22.97; r = 0.9973, respectively. The limit of detection (LOD) and limit of quantitation (LOQ) were calculated as 0.015 µM and 0.149 µM, respectively. The fabricated electrochemical sensor was successfully applied for determination of Amoxicillin in bovine milk samples and all results compared with high performance liquid chromatography (HPLC) standard method.

Matched MeSH terms: Gold/chemistry*
Fulltext Development of Highly Sensitive Immunosensor for Clenbuterol Detection by Using Poly(3,4-ethylenedioxythiophene)/Graphene Oxide Modified Screen-Printed Carbon Electrode

Talib NAA, Salam F, Sulaiman Y

Sensors (Basel), 2018 Dec 07;18(12).
PMID: 30544568 DOI: 10.3390/s18124324

Clenbuterol (CLB) is an antibiotic and illegal growth promoter drug that has a long half-life and easily remains as residue and contaminates the animal-based food product that leads to various health problems. In this work, electrochemical immunosensor based on poly(3,4-ethylenedioxythiophene)/graphene oxide (PEDOT/GO) modified screen-printed carbon electrode (SPCE) for CLB detection was developed for antibiotic monitoring in a food product. The modification of SPCE with PEDOT/GO as a sensor platform was performed through electropolymerization, while the electrochemical assay was accomplished while using direct competitive format in which the free CLB and clenbuterol-horseradish peroxidase (CLB-HRP) in the solution will compete to form binding with the polyclonal anti-clenbuterol antibody (Ab) immobilized onto the modified electrode surface. A linear standard CLB calibration curve with R² = 0.9619 and low limit of detection (0.196 ng mL-1) was reported. Analysis of milk samples indicated that this immunosensor was able to detect CLB in real samples and the results that were obtained were comparable with enzyme-linked immunosorbent assays (ELISA).

Matched MeSH terms: Gold/chemistry

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