Displaying publications 1 - 20 of 85 in total

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  1. Directed assembly of bifunctional silica-iron oxide nanocomposite with open shell structure
    Che HX, Yeap SP, Osman MS, Ahmad AL, Lim J
    ACS Appl Mater Interfaces, 2014 Oct 8;6(19):16508-18.
    PMID: 25198872 DOI: 10.1021/am5050949
    The synthesis of nanocomposite with controlled surface morphology plays a key role for pollutant removal from aqueous environments. The influence of the molecular size of the polyelectrolyte in synthesizing silica-iron oxide core-shell nanocomposite with open shell structure was investigated by using dynamic light scattering, atomic force microscopy, and quartz crystal microbalance with dissipation (QCM-D). Here, poly(diallydimethylammonium chloride) (PDDA) was used to promote the attachment of iron oxide nanoparticles (IONPs) onto the silica surface to assemble a nanocomposite with magnetic and catalytic bifunctionality. High molecular weight PDDA tended to adsorb on silica colloid, forming a more extended conformation layer than low molecular weight PDDA. Subsequent attachment of IONPs onto this extended PDDA layer was more randomly distributed, forming isolated islands with open space between them. By taking amoxicillin, an antibiotic commonly found in pharmaceutical waste, as the model system, better removal was observed for silica-iron oxide nanocomposite with a more extended open shell structure.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  2. Structural and Electrical Characterization of SiO2 Gate Dielectrics Deposited from Solutions at Moderate Temperatures in Air
    Esro M, Kolosov O, Jones PJ, Milne WI, Adamopoulos G
    ACS Appl Mater Interfaces, 2017 01 11;9(1):529-536.
    PMID: 27933760 DOI: 10.1021/acsami.6b11214
    Silicon dioxide (SiO2) is the most widely used dielectric for electronic applications. It is usually produced by thermal oxidation of silicon or by using a wide range of vacuum-based techniques. By default, the growth of SiO2 by thermal oxidation of silicon requires the use of Si substrates whereas the other deposition techniques either produce low quality or poor interface material and mostly require high deposition or annealing temperatures. Recent investigations therefore have focused on the development of alternative deposition paradigms based on solutions. Here, we report the deposition of SiO2 thin film dielectrics deposited by spray pyrolysis in air at moderate temperatures of ≈350 °C from pentane-2,4-dione solutions of SiCl4. SiO2 dielectrics were investigated by means of UV-vis absorption spectroscopy, spectroscopic ellipsometry, XPS, XRD, UFM/AFM, admittance spectroscopy, and field-effect measurements. Data analysis reveals smooth (RRMS < 1 nm) amorphous films with a dielectric constant of about 3.8, an optical band gap of ≈8.1 eV, leakage current densities in the order of ≈10(-7) A/cm(2) at 1 MV/cm, and high dielectric strength in excess of 5 MV/cm. XPS measurements confirm the SiO2 stoichiometry and FTIR spectra reveal features related to SiO2 only. Thin film transistors implementing spray-coated SiO2 gate dielectrics and C60 and pentacene semiconducting channels exhibit excellent transport characteristics, i.e., negligible hysteresis, low leakage currents, high on/off current modulation ratio on the order of 10(6), and high carrier mobility.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  3. Ordered mesoporous silica (OMS) as an adsorbent and membrane for separation of carbon dioxide (CO2)
    Chew TL, Ahmad AL, Bhatia S
    Adv Colloid Interface Sci, 2010 Jan 15;153(1-2):43-57.
    PMID: 20060956 DOI: 10.1016/j.cis.2009.12.001
    Separation of carbon dioxide (CO(2)) from gaseous mixture is an important issue for the removal of CO(2) in natural gas processing and power plants. The ordered mesoporous silicas (OMS) with uniform pore structure and high density of silanol groups, have attracted the interest of researchers for separation of carbon dioxide (CO(2)) using adsorption process. These mesoporous silicas after functionalization with amino groups have been studied for the removal of CO(2). The potential of functionalized ordered mesoporous silica membrane for separation of CO(2) is also recognized. The present paper reviews the synthesis of mesoporous silicas and important issues related to the development of mesoporous silicas. Recent studies on the CO(2) separation using ordered mesoporous silicas (OMS) as adsorbent and membrane are highlighted. The future prospectives of mesoporous silica membrane for CO(2) adsorption and separation are also presented and discussed.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  4. Anion exchange silica monolith for capillary liquid chromatography
    Jaafar J, Watanabe Y, Ikegami T, Miyamoto K, Tanaka N
    Anal Bioanal Chem, 2008 Aug;391(7):2551-6.
    PMID: 18458888 DOI: 10.1007/s00216-008-2063-3
    An anion exchange monolithic silica capillary column was prepared by surface modification of a hybrid monolithic silica capillary column prepared from a mixture of tetramethoxysilane (TMOS) and methyltrimethoxysilane (MTMS). The surface modification was carried out by on-column copolymerization of N-[3-(dimethylamino)propyl]acrylamide methyl chloride-quaternary salt (DMAPAA-Q) with 3-methacryloxypropyl moieties bonded as an anchor to the silica surface to form a strong anion exchange stationary phase. The columns were examined for their performance in liquid chromatography (LC) and capillary electrochromatography (CEC) separations of common anions. The ions were separated using 50 mM phosphate buffer at pH 6.6. Evaluation by LC produced an average of 30,000 theoretical plates (33 cm column length) for the inorganic anions and nucleotides. Evaluation by CEC, using the same buffer, produced enhanced chromatographic performance of up to ca. 90,000 theoretical plates and a theoretical plate height of ca. 4 mum. Although reduced efficiency was observed for inorganic anions that were retained a long time, the results of this study highlight the potential utility of the DMAPAA-Q stationary phase for anion separations.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  5. An ultrasensitive hollow-silica-based biosensor for pathogenic Escherichia coli DNA detection
    Ariffin EY, Lee YH, Futra D, Tan LL, Karim NHA, Ibrahim NNN, et al.
    Anal Bioanal Chem, 2018 Mar;410(9):2363-2375.
    PMID: 29504083 DOI: 10.1007/s00216-018-0893-1
    A novel electrochemical DNA biosensor for ultrasensitive and selective quantitation of Escherichia coli DNA based on aminated hollow silica spheres (HSiSs) has been successfully developed. The HSiSs were synthesized with facile sonication and heating techniques. The HSiSs have an inner and an outer surface for DNA immobilization sites after they have been functionalized with 3-aminopropyltriethoxysilane. From field emission scanning electron microscopy images, the presence of pores was confirmed in the functionalized HSiSs. Furthermore, Brunauer-Emmett-Teller (BET) analysis indicated that the HSiSs have four times more surface area than silica spheres that have no pores. These aminated HSiSs were deposited onto a screen-printed carbon paste electrode containing a layer of gold nanoparticles (AuNPs) to form a AuNP/HSiS hybrid sensor membrane matrix. Aminated DNA probes were grafted onto the AuNP/HSiS-modified screen-printed electrode via imine covalent bonds with use of glutaraldehyde cross-linker. The DNA hybridization reaction was studied by differential pulse voltammetry using an anthraquinone redox intercalator as the electroactive DNA hybridization label. The DNA biosensor demonstrated a linear response over a wide target sequence concentration range of 1.0×10-12-1.0×10-2 μM, with a low detection limit of 8.17×10-14 μM (R2 = 0.99). The improved performance of the DNA biosensor appeared to be due to the hollow structure and rough surface morphology of the hollow silica particles, which greatly increased the total binding surface area for high DNA loading capacity. The HSiSs also facilitated molecule diffusion through the silica hollow structure, and substantially improved the overall DNA hybridization assay. Graphical abstract Step-by-step DNA biosensor fabrication based on aminated hollow silica spheres.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  6. Fulltext Silica nanoparticles aid in structural leaf coloration in the Malaysian tropical rainforest understorey herb Mapania caudata
    Strout G, Russell SD, Pulsifer DP, Erten S, Lakhtakia A, Lee DW
    Ann Bot, 2013 Oct;112(6):1141-8.
    PMID: 23960046 DOI: 10.1093/aob/mct172
    BACKGROUND AND AIMS: Blue-green iridescence in the tropical rainforest understorey sedge Mapania caudata creates structural coloration in its leaves through a novel photonic mechanism. Known structures in plants producing iridescent blues consist of altered cellulose layering within cell walls and in special bodies, and thylakoid membranes in specialized plastids. This study was undertaken in order to determine the origin of leaf iridescence in this plant with particular attention to nano-scale components contributing to this coloration.

    METHODS: Adaxial walls of leaf epidermal cells were characterized using high-pressure-frozen freeze-substituted specimens, which retain their native dimensions during observations using transmission and scanning microscopy, accompanied by energy-dispersive X-ray spectroscopy to identify the role of biogenic silica in wall-based iridescence. Biogenic silica was experimentally removed using aqueous Na2CO3 and optical properties were compared using spectral reflectance.

    KEY RESULTS AND CONCLUSIONS: Blue iridescence is produced in the adaxial epidermal cell wall, which contains helicoid lamellae. The blue iridescence from cell surfaces is left-circularly polarized. The position of the silica granules is entrained by the helicoid microfibrillar layers, and granules accumulate at a uniform position within the helicoids, contributing to the structure that produces the blue iridescence, as part of the unit cell responsible for 2 ° Bragg scatter. Removal of silica from the walls eliminated the blue colour. Addition of silica nanoparticles on existing cellulosic lamellae is a novel mechanism for adding structural colour in organisms.

    Matched MeSH terms: Silicon Dioxide/chemistry*
  7. Robust Magnetized Oil Palm Leaves Ash Nanosilica Composite as Lipase Support: Immobilization Protocol and Efficacy Study
    Onoja E, Wahab RA
    Appl Biochem Biotechnol, 2020 Oct;192(2):585-599.
    PMID: 32495234 DOI: 10.1007/s12010-020-03348-0
    Strategies to immobilize the individual enzymes are crucial for enhancing catalytic applicability and require a controlled immobilization process. Herein, protocol for immobilizing Candida rugosa lipase (CRL) onto modified magnetic silica derived from oil palm leaves ash (OPLA) was optimized for the effects of concentration of CRL, immobilization time, and temperature, monitored by titrimetric and spectrometric methods. XRD and TGA-DTG spectrometric observations indicated that OPLA-silica was well coated over magnetite (SiO2-MNPs) and CRLs were uniformly bound by covalent bonds to SiO2-MNPs (CRL/Gl-A-SiO2-MNPs). The optimized immobilization protocol showed that in the preparation of CRL/Gl-A-SiO2-MNPs, CRL with 68.3 mg/g protein loading and 74.6 U/g specific activity was achieved using 5 mg/mL of CRL, with an immobilization time of 12 h at 25 °C. The present work also demonstrated that acid-pretreated OPLA is a potential source of renewable silica, envisioning its applicability for practical use in enzymatic catalysis on solid support.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  8. Photon irradiation response of photonic crystal fibres and flat fibres at radiation therapy doses
    Hashim S, Ibrahim SA, Che Omar SS, Alajerami YS, Saripan MI, Noor NM, et al.
    Appl Radiat Isot, 2014 Aug;90:258-60.
    PMID: 24858954 DOI: 10.1016/j.apradiso.2014.04.016
    Radiation effects of photon irradiation in pure Photonic Crystal Fibres (PCF) and Flat fibres (FF) are still much less investigated in thermoluminescense dosimetry (TLD). We have reported the TL response of PCF and FF subjected to 6 MV photon irradiation. The proposed dosimeter shows good linearity at doses ranging from 1 to 4 Gy. The small size of these detectors points to its use as a dosimeter at megavoltage energies, where better tissue-equivalence and the Bragg-Gray cavity theory prevails.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  9. The thermoluminescence response of doped SiO2 optical fibres subjected to fast neutrons
    Hashim S, Bradley DA, Saripan MI, Ramli AT, Wagiran H
    Appl Radiat Isot, 2010 Apr-May;68(4-5):700-3.
    PMID: 19892557 DOI: 10.1016/j.apradiso.2009.10.027
    This paper describes a preliminary study of the thermoluminescence (TL) response of doped SiO(2) optical fibres subjected to (241)AmBe neutron irradiation. The TL materials, which comprise Al- and Ge-doped silica fibres, were exposed in close contact with the (241)AmBe source to obtain fast neutron interactions through use of measurements obtained with and without a Cd filter (the filter being made to entirely enclose the fibres). The neutron irradiations were performed for exposure times of 1-, 2-, 3-, 5- and 7-days in a neutron tank filled with water. In this study, use was also made of the Monte Carlo N-particle (MCNP) code version 5 (V5) to simulate the neutron irradiations experiment. It was found that the commercially available Ge-doped and Al-doped optical fibres show a linear dose response subjected to fast neutrons from (241)AmBe source up to seven days of irradiations. The simulation performed using MCNP5 also exhibits a similar pattern, albeit differing in sensitivity. The TL response of Ge-doped fibre is markedly greater than that of the Al-doped fibre, the total absorption cross section for Ge in both the fast and thermal neutrons region being some ten times greater than that of Al.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  10. The thermoluminescence glow curve and the deconvoluted glow peak characteristics of erbium doped silica fiber exposed to 70-130 kVp x-rays
    Alawiah A, Bauk S, Marashdeh MW, Nazura MZ, Abdul-Rashid HA, Yusoff Z, et al.
    Appl Radiat Isot, 2015 Oct;104:197-202.
    PMID: 26188687 DOI: 10.1016/j.apradiso.2015.07.011
    In regard to thermoluminescence (TL) applied to dosimetry, in recent times a number of researchers have explored the role of optical fibers for radiation detection and measurement. Many of the studies have focused on the specific dopant concentration, the type of dopant and the fiber core diameter, all key dependencies in producing significant increase in the sensitivity of such fibers. At doses of less than 1 Gy none of these investigations have addressed the relationship between dose response and TL glow peak behavior of erbium (Er)-doped silica cylindrical fibers (CF). For x-rays obtained at accelerating potentials from 70 to 130 kVp, delivering doses of between 0.1 and 0.7 Gy, present study explores the issue of dose response, special attention being paid to determination of the kinetic parameters and dosimetric peak properties of Er-doped CF. The effect of dose response on the kinetic parameters of the glow peak has been compared against other fiber types, revealing previously misunderstood connections between kinetic parameters and radiation dose. Within the investigated dose range there was an absence of supralinearity of response of the Er-doped silica CF, instead sub-linear response being observed. Detailed examination of glow peak response and kinetic parameters has thus been shown to shed new light of the rarely acknowledged issue of the limitation of TL kinetic model and sub-linear dose response of Er-doped silica CF.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  11. Radioluminescence of cylindrical and flat Ge-doped silica optical fibers for real-time dosimetry applications
    Oresegun A, Tarif ZH, Ghassan L, Zin H, Abdul-Rashid HA, Bradley DA
    Appl Radiat Isot, 2021 Oct;176:109812.
    PMID: 34166948 DOI: 10.1016/j.apradiso.2021.109812
    Investigation has been made of the radioluminescence dose response of Ge-doped silica flat and cylindrical fibers subjected to 6 and 10 MV photon beams. The fibers have been custom fabricated, obtaining Ge dopant concentrations of 6 and 10 mol%, subsequently cut into 20 mm lengths. Each sample has been exposed under a set of similar conditions, with use made of a fixed field size and source to surface distance (SSD). Investigation of dosimetric performance has involved radioluminescence linearity, dose-rate dependence, energy dependence, and reproducibility. Mass for mass, the 6 mol% Ge-doped samples provided the greater radioluminescence yield, with both flat and cylindrical fibers responding linearly to the absorbed dose. Further found has been that the cylindrical fibers provided a yield some 38% greater than that of the flat fibers. At 6 MV, the cylindrical fibers were also found to exhibit repeatability variation of <1%, superior to that of the flat fibers, offering strong potential for use in real-time dosimetry applications.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  12. Detection of Salmonella bacterium in drinking water using microring resonator
    Bahadoran M, Noorden AF, Mohajer FS, Abd Mubin MH, Chaudhary K, Jalil MA, et al.
    Artif Cells Nanomed Biotechnol, 2016;44(1):315-21.
    PMID: 25133457 DOI: 10.3109/21691401.2014.948549
    A new microring resonator system is proposed for the detection of the Salmonella bacterium in drinking water, which is made up of SiO2-TiO2 waveguide embedded inside thin film layer of the flagellin. The change in refractive index due to the binding of the Salmonella bacterium with flagellin layer causes a shift in the output signal wavelength and the variation in through and drop port's intensities, which leads to the detection of Salmonella bacterium in drinking water. The sensitivity of proposed sensor for detecting of Salmonella bacterium in water solution is 149 nm/RIU and the limit of detection is 7 × 10(-4)RIU.
    Matched MeSH terms: Silicon Dioxide/chemistry
  13. Well-ordered mesoporous silica and bioactive glasses: promise for improved hemostasis
    Pourshahrestani S, Kadri NA, Zeimaran E, Towler MR
    Biomater Sci, 2018 Dec 18;7(1):31-50.
    PMID: 30374499 DOI: 10.1039/c8bm01041b
    Immediate control of uncontrolled bleeding and infection are essential for saving lives in both combat and civilian arenas. Inorganic well-ordered mesoporous silica and bioactive glasses have recently shown great promise for accelerating hemostasis and infection control. However, to date, there has been no comprehensive report assessing their specific mechanism of action in accelerating the hemostasis process and exerting an antibacterial effect. After providing a brief overview of the hemostasis process, this review presents a critical overview of the recently developed inorganic mesoporous silica and bioactive glass-based materials proposed for hemostatic clinical applications and specifically investigates their unique characteristics that render them applicable for hemostatic applications and preventing infections. This article also identifies promising new research directions that should be undertaken to ascertain the effectiveness of these materials for hemostatic applications.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  14. A rapid MCM-41 dispersive micro-solid phase extraction coupled with LC/MS/MS for quantification of ketoconazole and voriconazole in biological fluids
    Yahaya N, Sanagi MM, Abd Aziz N, Wan Ibrahim WA, Nur H, Loh SH, et al.
    Biomed Chromatogr, 2017 Feb;31(2).
    PMID: 27474795 DOI: 10.1002/bmc.3803
    A rapid dispersive micro-solid phase extraction (D-μ-SPE) combined with LC/MS/MS method was developed and validated for the determination of ketoconazole and voriconazole in human urine and plasma samples. Synthesized mesoporous silica MCM-41 was used as sorbent in d-μ-SPE of the azole compounds from biological fluids. Important D-μ-SPE parameters, namely type desorption solvent, extraction time, sample pH, salt addition, desorption time, amount of sorbent and sample volume were optimized. Liquid chromatographic separations were carried out on a Zorbax SB-C18 column (2.1 × 100 mm, 3.5 μm), using a mobile phase of acetonitrile-0.05% formic acid in 5 mm ammonium acetate buffer (70:30, v/v). A triple quadrupole mass spectrometer with positive ionization mode was used for the determination of target analytes. Under the optimized conditions, the calibration curves showed good linearity in the range of 0.1-10,000 μg/L with satisfactory limit of detection (≤0.06 μg/L) and limit of quantitation (≤0.3 μg/L). The proposed method also showed acceptable intra- and inter-day precisions for ketoconazole and voriconazole from urine and human plasma with RSD ≤16.5% and good relative recoveries in the range 84.3-114.8%. The MCM-41-D-μ-SPE method proved to be rapid and simple and requires a small volume of organic solvent (200 μL); thus it is advantageous for routine drug analysis.
    Matched MeSH terms: Silicon Dioxide/chemistry
  15. Ethyl-4-(aryl)-6-methyl-2-(oxo/thio)-3,4-dihydro-1H-pyrimidine-5-carboxylates: Silica supported bismuth(III)triflate catalyzed synthesis and antioxidant activity
    Gajjala RR, Chinta RR, Gopireddy VSR, Poola S, Balam SK, Chintha V, et al.
    Bioorg Chem, 2022 Dec;129:106205.
    PMID: 36265354 DOI: 10.1016/j.bioorg.2022.106205
    Novel ethyl-4-(aryl)-6-methyl-2-(oxo/thio)-3,4-dihydro-1H-pyrimidine-5-carboxylates were synthesized from one-pot, three-component Biginelli reaction of aryl aldehydes, ethyl acetoacetate and urea/ thiourea by catalytic action of silica supported Bismuth(III) triflate, a Lewis acid. All the synthesized compounds were structurally characterized by spectral (IR, 1H NMR & 13C NMR spectroscopic and Mass spectrometric) and elemental (C, H & N) analyses. The present protocol has deserved novel as, formed the products in high yields with short reaction times, involved eco-friendly methodology and reusable heterogeneous Lewis acid catalyst. The title compounds were screened for in vitro DPPH free radical scavenging antioxidant activity and identified 4i, 4j, 4h & 4f as potential antioxidants. The obtained in vitro results were correlated with molecular docking, ADMET, QSAR, Bioactivity & toxicity risk studies and molecular finger print properties and found that in silico binding affinities were identified in good correlation with in vitro antioxidant activity and studied the structure activity relationship. The molecular docking study has disclosed strong hydrogen bonding interactions of title compounds with aspartic acid (ASP197) aminoacid residue of 2HCK, a complex enzyme of haematopoietic cell kinase and quercetin. Results of toxicology study evaluated for potential risks of compounds have revealed title compounds as safer drugs. In ultimate the study has established ligand's antioxidant potentiality as they effectively binds with ASP197 amino acid of Chain A hence confirms the inhibition of growth of reactive oxygen species in vivo. In addition, the title compounds have been identified as potential blood-brain barrier penetrable entities and efficient central nervous system (CNS) active neuro-protective antioxidant agents.
    Matched MeSH terms: Silicon Dioxide/chemistry
  16. Effects of co-substrate and biomass acclimation concentration on the bioregeneration of azo dye-loaded mono-amine modified silica
    Al-Amrani WA, Lim PE, Seng CE, Wan Ngah WS
    Bioresour Technol, 2013 Sep;143:584-91.
    PMID: 23835263 DOI: 10.1016/j.biortech.2013.06.055
    Bioregeneration of mono-amine modified silica gel (MAMS) adsorbent loaded with Acid Orange 7 (AO7), Acid Yellow 9 (AY9) and Acid Red 14 (AR14), respectively, was investigated under two different operational conditions, namely absence/presence of sucrose/bacto-peptone as the co-substrate and different biomass acclimation concentrations. The results revealed that the AY9- and AR14-loaded MAMS adsorbents could almost be completely bioregenerated but only in the presence of co-substrate whereas the bioregeneration of AO7-loaded MAMS could achieve up to 71% in the absence of the co-substrate. These differences could be related to the structural properties of the investigated azo dyes. In addition, the results showed that the bioregeneration duration of AO7-loaded MAMS could be progressively shortened by using biomass acclimated to increasingly higher AO7 concentration. However, the bioregeneration efficiencies were found to be relatively unchanged under different biomass acclimation concentrations.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  17. Bioregeneration of mono-amine modified silica and granular activated carbon loaded with Acid Orange 7 in batch system
    Al-Amrani WA, Lim PE, Seng CE, Ngah WS
    Bioresour Technol, 2012 Aug;118:633-7.
    PMID: 22704829 DOI: 10.1016/j.biortech.2012.05.090
    The objectives of this study were: (1) to investigate the role of mixed culture of biomass in the regeneration of mono-amine modified silica (MAMS) and granular activated carbon (GAC) loaded with Acid Orange 7 (AO7), (2) to quantify and compare the bioregeneration efficiencies of AO7-loaded MAMS and GAC using the sequential adsorption and biodegradation approach and (3) to evaluate the reusability of bioregenerated MAMS. The results show that considerably higher bioregeneration efficiency of AO7-loaded MAMS as compared to that of AO7-loaded GAC was achieved due to higher reversibility of adsorption of MAMS for AO7 and favorable pH factor resulting in more AO7 desorption. The progressive loss of adsorption capacity of MAMS for AO7 with multiple cycles of use suggests possible chemical and microbial fouling of the adsorption sites.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  18. Highly sensitive Escherichia coli shear horizontal surface acoustic wave biosensor with silicon dioxide nanostructures
    Ten ST, Hashim U, Gopinath SC, Liu WW, Foo KL, Sam ST, et al.
    Biosens Bioelectron, 2017 Jul 15;93:146-154.
    PMID: 27660016 DOI: 10.1016/j.bios.2016.09.035
    Surface acoustic wave mediated transductions have been widely used in the sensors and actuators applications. In this study, a shear horizontal surface acoustic wave (SHSAW) was used for the detection of food pathogenic Escherichia coli O157:H7 (E.coli O157:H7), a dangerous strain among 225 E. coli unique serotypes. A few cells of this bacterium are able to cause young children to be most vulnerable to serious complications. Presence of higher than 1cfu E.coli O157:H7 in 25g of food has been considered as a dangerous level. The SHSAW biosensor was fabricated on 64° YX LiNbO3 substrate. Its sensitivity was enhanced by depositing 130.5nm thin layer of SiO2 nanostructures with particle size lesser than 70nm. The nanostructures act both as a waveguide as well as a physical surface modification of the sensor prior to biomolecular immobilization. A specific DNA sequence from E. coli O157:H7 having 22 mers as an amine-terminated probe ssDNA was immobilized on the thin film sensing area through chemical functionalization [(CHO-(CH2)3-CHO) and APTES; NH2-(CH2)3-Si(OC2H5)3]. The high-performance of sensor was shown with the specific oligonucleotide target and attained the sensitivity of 0.6439nM/0.1kHz and detection limit was down to 1.8femto-molar (1.8×10(-15)M). Further evidence was provided by specificity analysis using single mismatched and complementary oligonucleotide sequences.
    Matched MeSH terms: Silicon Dioxide/chemistry
  19. Silica nanoparticle assists determining liver cancer gene sequence on interdigitated electrode surface
    Song F, Yang Y, Gopinath SCB
    Biotechnol Appl Biochem, 2021 Jun;68(3):683-689.
    PMID: 32628799 DOI: 10.1002/bab.1980
    A high-performance interdigitated electrode (IDE) biosensing surface was reported here by utilizing self-assembled silica nanoparticle (SiNP). The modified surface was used to evaluate the complementation of hairpin forming region from Mitoxantrone resistance gene 7 (MXR7; liver cancer-related short gene). The conjugated SiNPs on 3-aminopropyl triethoxysilane functionalization were captured with probe sequence on IDE biosensing surface. The physical and chemically modified surface was used to quantify MXR7 and an increment in the current response upon complementation was noticed. Limit of target DNA detection was calculated (1-10 fM) and this label-free detection is at the comparable level to the fluorescent-based sensing. A linear regression was calculated [y = 0.243x - 0.0773; R² = 0.9336] and the sensitivity was 1 fM on the linear range of 1 fM to 10 pM. With the strong attachment of capture DNA on IDE through SiNP, the surface clearly discriminates the specificity (complementary) versus nonspecificity (complete-, single-, and triple-mismatched sequences). This detection strategy helps to determine liver cancer progression and the similar strategy can be followed for other gene sequence complementation.
    Matched MeSH terms: Silicon Dioxide/chemistry*
  20. Catalyst free silica templated porous carbon nanoparticles from bio-waste materials
    Kumar A, Hegde G, Manaf SA, Ngaini Z, Sharma KV
    Chem Commun (Camb), 2014 Oct 28;50(84):12702-5.
    PMID: 25100105 DOI: 10.1039/c4cc04378b
    Porous Carbon Nanoparticles (PCNs) with well-developed microporosity were obtained from bio-waste oil palm leaves (OPL) using single step pyrolysis in nitrogen atmosphere at 500-600 °C in tube-furnace without any catalysis support. The key approach was using silica (SiO2) bodies of OPL as a template in the synthesis of microporous carbon nanoparticles with very small particle sizes of 35-85 nm and pore sizes between 1.9-2 nm.
    Matched MeSH terms: Silicon Dioxide/chemistry*
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