Publications by authors named "Khairunisak Abdul Razak"

17 Publications

  • Page 1 of 1

Synergetic Influence of Bismuth Oxide Nanoparticles, Cisplatin and Baicalein-Rich Fraction on Reactive Oxygen Species Generation and Radiosensitization Effects for Clinical Radiotherapy Beams.

Int J Nanomedicine 2020 12;15:7805-7823. Epub 2020 Oct 12.

Medical Radiation Programme, School of Health Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan,Malaysia.

Purpose: This study aimed to quantify synergetic effects induced by bismuth oxide nanoparticles (BiONPs), cisplatin (Cis) and baicalein-rich fraction (BRF) natural-based agent on the reactive oxygen species (ROS) generation and radiosensitization effects under irradiation of clinical radiotherapy beams of photon, electron and HDR-brachytherapy. The combined therapeutic responses of each compound and clinical radiotherapy beam were evaluated on breast cancer and normal fibroblast cell line.

Methods: In this study, individual BiONPs, Cis, and BRF, as well as combinations of BiONPs-Cis (BC), BiONPs-BRF (BB) and BiONPs-Cis-BRF (BCB) were treated to the cells before irradiation using HDR brachytherapy with 0.38 MeV iridium-192 source, 6 MV photon beam and 6 MeV electron beam. The individual or synergetic effects from the application of the treatment components during the radiotherapy were elucidated by quantifying the ROS generation and radiosensitization effects on MCF-7 and MDA-MB-231 breast cancer cell lines as well as NIH/3T3 normal cell line.

Results: The ROS generated in the presence of Cis stimulated the most substantial amount of ROS compared to the BiONPs and BRF. Meanwhile, the combination of the components had induced the higher ROS levels for photon beam than the brachytherapy and electron beam. The highest ROS enhancement relative to the control is attributable to the presence of BC combination in MDA-MB-231 cells, in comparison to the BB and BCB combinations. The radiosensitization effects which were quantified using the sensitization enhancement ratio (SER) indicate the highest value by BC in MCF-7 cells, followed by BCB and BB treatment. The radiosensitization effects are found to be more prominent for brachytherapy in comparison to photon and electron beam.

Conclusion: The BiONPs, Cis and BRF are the potential radiosensitizers that could improve the efficiency of radiotherapy to eradicate the cancer cells. The combination of these potent radiosensitizers might produce multiple effects when applied in radiotherapy. The BC combination is found to have the highest SER, followed by the BCB combination. This study is also the first to investigate the effect of BRF in combination with BiONPs (BB) and BC (BCB) treatments.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2147/IJN.S269214DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7567565PMC
November 2020

Development of rapid gold nanoparticles based lateral flow assays for simultaneous detection of Shigella and Salmonella genera.

Biotechnol Appl Biochem 2020 Sep 16. Epub 2020 Sep 16.

School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Nibong Tebal, Penang, Malaysia.

Salmonella and Shigella genera are common pathogens that contaminate foods and beverages. Lateral flow assays (LFA) are commonly used to detect these pathogens. However, most of the developed LFAs are for single detection. Simultaneous detection of pathogens is required to reduce cost and time. In this work, 40 nm gold nanoparticles (AuNPs) were synthesized using the seeding growth method as labeling agent. The AuNPs were characterized and conjugated with mouse anti-Gram negative endotoxin antibody. The nitrocellulose membrane HF135 was immobilized with anti-mouse IgG antibody as a control line and two separate test lines with either anti-Shigella or anti-Salmonella antibody, respectively. Color intensity of test lines was observed for positive samples. A milk sample was used as proof of concept to mimic actual contamination. The limit of detection of the LFA was 3.0 × 10 CFU/mL for multiplex detection of Shigella flexneri and Salmonella Typhi and for both single detections. The result was comparable with the enzyme-linked immunosorbent assay (ELISA) analysis. The produced LFA could differentiate between Shigella flexneri, Shigella boydii, Salmonella Enteritidis, and Salmonella Typhi. The developed LFA was able to identify Shigella flexneri and Salmonella Typhi with good sensitivity in milk samples, thus, beneficial to ensure the safety of food before entering the market.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/bab.2029DOI Listing
September 2020

Formation of grassy TiO nanotube thin film by anodisation in peroxide electrolyte for Cr(VI) removal under ultraviolet radiation.

Nanotechnology 2020 Oct 8;31(43):435605. Epub 2020 Jul 8.

Green Electronics Oxide nanoMaterials Group (GEM), School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300, Nibong Tebal, Penang, Malaysia. Advanced Technology Training Centre (ADTEC) Taiping, PT 15643, Kamunting Raya, Mukim Asam Kumbang, 34600, Kamunting, Perak, Malaysia.

Arrays of TiO nanotubes (TiO NTs) with grassy surfaces were observed on titanium foil anodised at 60 V in fluorinated ethylene glycol (EG) with added hydrogen peroxide (HO). The grassy surface was generated by the chemical etching and dissolution of the surface of the TiO NTs walls, which was accelerated by the temperature increase on the addition of HO . Upon annealing at 600 °C, the grassy part of the TiO NTs was found to consist of mostly anatase TiO whereas the bottom part of the anodic oxide comprised a mixture of anatase and rutile TiO. The TiO NTs were then used to reduce hexavalent chromium (Cr(VI)) under ultraviolet radiation. They exhibited a rather efficient photocatalytic effect, with 100% removal of Cr(VI) after 30 min of irradiation. The fast removal of Cr(VI) was due to the anatase dominance at the grassy part of the TiO NTs as well as the higher surface area the structure may have. This work provides a novel insight into the photocatalytic reduction of Cr(VI) on grassy anatase TiO NTs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1088/1361-6528/aba3d8DOI Listing
October 2020

Radiosensitization Effects by Bismuth Oxide Nanoparticles in Combination with Cisplatin for High Dose Rate Brachytherapy.

Int J Nanomedicine 2019 18;14:9941-9954. Epub 2019 Dec 18.

School of Health Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia.

Purpose: The aim of this study was to investigate the potential of the synergetic triple therapeutic combination encompassing bismuth oxide nanoparticles (BiONPs), cisplatin (Cis), and high dose rate (HDR) brachytherapy with Ir-192 source in breast cancer and normal fibroblast cell line.

Methods: In vitro models of breast cancer cell lines (MCF-7, MDA-MB-231) and normal fibroblast cell line (NIH/3T3) were employed. Cellular localization and cytotoxicity studies were conducted prior to inspection on the radiosensitization effects and generation of reactive oxygen species (ROS) on three proposed radiosensitizers: BiONPs, Cis, and BiONPs-Cis combination (BC). The optimal, non-cytotoxic concentration of BiONPs (0.5 mM) and the 25% inhibitory concentration of Cis (1.30 µM) were applied. The radiosensitization effects were evaluated by using a 0.38 MeV Iridium-192 HDR brachytherapy source over a prescribed dose range of 0 Gy to 4 Gy.

Results: The cellular localization of BiONPs was visualized by light microscopy and accumulation of the BiONPs within the vicinity of the nuclear membrane was observed. Quantification of the sensitization enhancement ratio extrapolated from the survival curves indicates radiosensitization effects for MCF-7 and MDA-MB-231 when treated with BiONPs, Cis, and BC. However, NIH/3T3 cells exhibited contradictive behavior as it only reacted towards the BC combination. Nonetheless, the MCF-7 cell line loaded with BC shows the highest SER of 4.29. ROS production analysis, on the other hand, shows that Cis and BC radiosensitizers generated the highest free radicals in comparison to BiONPs alone.

Conclusion: A BiONPs-Cis combination was unveiled as a novel approach that offers promising radiosensitization enhancement that will increase the efficiency of tumor control while preserving the normal tissue at a reduced dose. This data is the first precedent to prove the synergetic implication of BiONPs, Cis, and HDR brachytherapy that will be beneficial for future chemoradiotherapy strategies in cancer care.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2147/IJN.S228919DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6927229PMC
April 2020

Fabrication and Characterization of Glucose Biosensors by Using Hydrothermally Grown ZnO Nanorods.

Sci Rep 2018 09 13;8(1):13722. Epub 2018 Sep 13.

School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300, Nibong Tebal, Penang, Malaysia.

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 mol/cm, 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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-018-32127-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6137152PMC
September 2018

Sunlight activated anodic freestanding ZrO nanotube arrays for Cr(VI) photoreduction.

Nanotechnology 2018 Sep 14;29(37):375701. Epub 2018 Jun 14.

School of Materials Engineering, Universiti Malaysia Perlis, Kompleks Pusat Pengajian Jejawi 2, Taman Muhibbah, 02600 Jejawi, Arau, Perlis, Malaysia. Green Electronics Nanomaterials Group, School of Materials & Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Seri Ampangan, Nibong Tebal, Seberang Prai Selatan, Pulau Pinang, Malaysia.

Visible-light-active freestanding zirconia (ZrO) nanotube (FSZNT) arrays were fabricated by a facile electrochemical anodization method in fluoride containing ethylene glycol electrolyte added to it was 1 vol% of potassium carbonate (KCO) at 60 V for 1 h. Poor adhesion at the metal∣oxide interface was induced by KCO leading to the formation of FSZNT flakes. The effect of the crystal structures of the FSZNTs e.g., amorphous, amorphous/tetragonal, and tetragonal/monoclinic was investigated towards the photocatalytic reduction of 10 ppm hexavalent chromium, Cr(VI) at pH 2 under sunlight. The results demonstrate the amorphous FSZNTs exhibited the highest Cr(VI) removal efficiency than the crystalline FSZNTs (95% versus 33% after 5 h). The high photocatalytic activity of the amorphous FSZNTs can be attributed to enhanced Cr(VI) adsorption, high visible light absorption, and better charge carrier separation. The low photocatalytic activity of the crystalline FSZNTs annealed at 500 °C was mainly attributed to poor Cr(VI) adsorption, low visible light absorption, and less photoactive monoclinic-ZrO.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1088/1361-6528/aaccbdDOI Listing
September 2018

Encapsulation efficacy of natural and synthetic photosensitizers by silica nanoparticles for photodynamic applications.

IET Nanobiotechnol 2015 Dec;9(6):381-5

NanoBiotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 USM, Penang, Malaysia.

This study analysed the physical effects of Cichorium Pumilum (CP), as a natural photosensitizer (PS), and Protoporphyrin IX (PpIX), as a synthetic PS, encapsulated with silica nanoparticles (SiNPs) in photodynamic therapy. The optimum concentrations of CP and PpIX, needed to destroy Red Blood Cells (RBC), were determined and the efficacy of encapsulated CP and PpIX were compared with naked CP and PpIX was verified. The results confirmed the applicability of CP and PpIX encapsulated in SiNPs on RBCs, and established a relationship between the encapsulated CP and PpIX concentration and the time required to rupture 50% of the RBCs (t50). The CP and PpIX encapsulated in SiNPs exhibited higher efficacy compared with that of naked CP and PpIX, respectively, and CP had less efficacy compared with PpIX.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1049/iet-nbt.2015.0003DOI Listing
December 2015

Nanotoxic profiling of novel iron oxide nanoparticles functionalized with perchloric acid and SiPEG as a radiographic contrast medium.

Biomed Res Int 2015 17;2015:183525. Epub 2015 May 17.

Department of Medical Laboratory Technology, Faculty of Health Sciences, Universiti Teknologi MARA, UiTM Puncak Alam, 42300 Selangor, Malaysia.

Emerging syntheses and findings of new metallic nanoparticles (MNPs) have become an important aspect in various fields including diagnostic imaging. To date, iodine has been utilized as a radiographic contrast medium. However, the raise concern of iodine threats on iodine-intolerance patient has led to search of new contrast media with lower toxic level. In this animal modeling study, 14 nm iron oxide nanoparticles (IONPs) with silane-polyethylene glycol (SiPEG) and perchloric acid have been assessed for toxicity level as compared to conventional iodine. The nanotoxicity of IONPs was evaluated in liver biochemistry, reactive oxygen species production (ROS), lipid peroxidation mechanism, and ultrastructural evaluation using transmission electron microscope (TEM). The hematological analysis and liver function test (LFT) revealed that most of the liver enzymes were significantly higher in iodine-administered group as compared to those in normal and IONPs groups (P < 0.05). ROS production assay and lipid peroxidation indicator, malondialdehyde (MDA), also showed significant reductions in comparison with iodine group (P < 0.05). TEM evaluation yielded the aberration of nucleus structure of iodine-administered group as compared to those in control and IONPs groups. This study has demonstrated the less toxic properties of IONPs and it may postulate that IONPs are safe to be applied as radiographic contrast medium.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1155/2015/183525DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4449877PMC
April 2016

Artificial tissue sensitized with encapsulated methylene blue encapsulated by silica nanoparticles in photodynamic therapy.

Artif Cells Nanomed Biotechnol 2016 Aug 26;44(5):1285-9. Epub 2015 Mar 26.

b School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia , Nibong Tebal, Penang , Malaysia.

Background/aims: The synthesis of methylene blue (MB) encapsulated in silica nanoparticles (SiNPs) as an application for photodynamic therapy is reported in this study. Semi-rigid tissues with optical properties similar to that of human tissues were used as sample materials to determine the applicability of MB encapsulated in SiNPs.

Materials And Methods: The changes in optical properties of the tissue treated with encapsulated MB under light exposure (Intensity at 664 nm ∼11.9 mW/cm(2)) were observed. The optimal exposure time required for naked MB and MB-SiNP to destroy red blood cells (RBCs) in the artificial tissue was also determined.

Results: The comparative analysis between the results of applying naked MB and MB encapsulated in SiNPs in the treatment of artificial tissue confirmed that the encapsulated MB is 62 percent higher in efficacy than naked MB. The results established the applicability of MB encapsulated in SiNP on artificial tissue and possible application on human tissue.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3109/21691401.2015.1024843DOI Listing
August 2016

The efficacy of methylene blue encapsulated in silica nanoparticles compared to naked methylene blue for photodynamic applications.

Artif Cells Nanomed Biotechnol 2016 May 24;44(3):1018-22. Epub 2015 Feb 24.

b Engineering Department, School of Materials and Mineral Resources Engineering , Universiti Sains Malaysia , Penang , Malaysia.

Background/aims: This study analyzed the physical effects of methylene blue (MB) encapsulated within silica nanoparticles (SiNPs) in photodynamic therapy.

Materials And Methods: The optimum concentration of MB needed to destroy red blood cells (RBCs) was determined, and the efficacy of encapsulated MB-SiNPs compared to that of naked MB was verified.

Results: The results confirmed the applicability of MB encapsulated in SiNPs on RBCs, and established a relationship between the concentration of the SiNP-encapsulated MB and the time required to rupture 50% of the RBCs (t50).

Conclusion: The MB encapsulated in SiNPs exhibited higher efficacy compared to that of naked MB.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3109/21691401.2015.1008511DOI Listing
May 2016

Formation of two-dimensional ZnO nanosheets by rapid thermal oxidation in oxygenated environment.

J Nanosci Nanotechnol 2014 Apr;14(4):2960-7

Crystalline 2-D (dimensional) ZnO nanosheets were formed by rapid thermal oxidation of etched Zn foil in oxygen at 300 degrees C and 400 degrees C. Short oxidation time was varied from 10, 20 and 30 min. The morphologies and optical properties of the ZnO nanosheets evolved with the oxidation temperature and time. At 300 degrees C, ZnO nanosheets with thickness ranging from 32 nm to 80 nm were obtained while at 400 degrees C, the thickness of the nanosheets increased from 88 nm to approximately 200 nm after 10 and 30 min of oxidation, respectively. The surface roughness of the ZnO nanosheets and grain size increased with oxidation time and temperature. Photoluminescence of the oxidized samples shows ultraviolet (UV) and visible emissions indicating good crystallinity of ZnO which was further confirmed by high-resolution transmission electron microscope observation of ZnO wurtzite interplanar spacing. Photocatalytic activity of ZnO was also investigated by using degradation of methyl orange (MO) and all the samples exhibit photocatalytic activity. The sample oxidized at 400 degrees C for 10 min show better MO degradation after 2 h of exposure due to higher surface area and better crystallinity of the ZnO nanosheets obtained.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1166/jnn.2014.8559DOI Listing
April 2014

Production of recombinant Entamoeba histolytica pyruvate phosphate dikinase and its application in a lateral flow dipstick test for amoebic liver abscess.

BMC Infect Dis 2014 Apr 4;14:182. Epub 2014 Apr 4.

Institute for Research in Molecular Medicine, Universiti Sains Malaysia, Penang 11800, Malaysia.

Background: Amoebic liver abscess (ALA) is the most common clinical manifestation of extraintestinal amoebiasis especially in developing countries, causing up to 100 000 fatal cases annually. Accurate and early diagnosis is important to prevent the disease complications, however its diagnosis still poses many challenges due to the limitations of the available detection tools. Pyruvate phosphate dikinase (PPDK), an excretory-secretory protein of E. histolytica, has been reported as a potential diagnostic marker for ALA, hence it may be exploited in the development of a new test for ALA.

Methods: Recombinant PPDK (rPPDK) was expressed, purified and evaluated by Western blot. In parallel, recombinant galactose-and-N-acetyl-D-galactosamine inhibitable lectin (Gal/GalNAc lectin) was produced and tested similarly. The protein identity was confirmed by analysis using MALDI-TOF/TOF. A lateral flow dipstick (LFD) test using rPPDK was subsequently developed (rPPDK-LFD) and evaluated for serodiagnosis of ALA.

Results: rPPDK was expressed as soluble protein after 4 hours of induction with 1 mM isopropyl β-D-1-thiogalactopyranoside (IPTG) at 30°C. Purification using nickel-nitrilotriacetic acid (Ni-NTA) resin yielded 1.5 mg of rPPDK from 1 L of culture with estimated molecular mass of 98 kDa on SDS-PAGE. Western blots using sera from patients with ALA, healthy individuals and other diseases probed with anti-human IgG4-HRP showed the highest sensitivity (93.3%) and specificity (100%); as compared to blots using IgG and IgG1 as secondary antibodies. Moreover, rPPDK showed better specificity when compared to rGal/GalNAc lectin. In the development of the LFD test, the optimum amount of rPPDK was 0.625 μg per dipstick and the optimum working concentration of colloidal gold conjugated anti-human IgG4 was optical density (OD) 5 (1.7 μg of anti-human IgG4). Evaluation of rPPDK-LFD using ALA patients and controls serum samples showed 87% diagnostic sensitivity and 100% specificity.

Conclusion: The developed rPPDK-LFD showed good potential for rapid diagnosis of ALA, and merit further multicentre validation using larger number of serum samples.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/1471-2334-14-182DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3986461PMC
April 2014

Gold nanoparticles deposited on linker-free silicon substrate and embedded in aluminum Schottky contact.

J Colloid Interface Sci 2013 Oct 25;408:220-8. Epub 2013 Jul 25.

Electronic Materials Research Group, School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang, Malaysia.

Given the enormous importance of Au nanoparticles (NPs) deposition on Si substrates as the precursor for various applications, we present an alternative approach to deposit Au NPs on linker-free n- and p-type Si substrates. It is demonstrated that, all conditions being similar, there is a significant difference between densities of the deposited NPs on both substrates. The Zeta-potential and polarity of charges surrounding the hydroxylamine reduced seeded growth Au NPs, are determined by a Zetasizer. To investigate the surface properties of Si substrates, contact angle measurement is performed. Field-emission scanning electron microscope is then utilized to distinguish the NPs density on the substrates. Finally, Al/Si Schottky barrier diodes with embedded Au NPs are fabricated, and their structural and electrical characteristics are further evaluated using an energy-filtered transmission electron microscope and current-voltage measurements, respectively. The results reveal that the density of NPs is significantly higher on n-type Si substrate and consequently has more pronounced effects on the electrical characteristics of the diode. It is concluded that protonation of Si-OH group on Si surface in low pH is responsible for the immobilization of Au NPs, which eventually contributes to the lowering of barrier height and enhances the electrical characteristics.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jcis.2013.07.026DOI Listing
October 2013

Structural and morphology of ZnO nanorods synthesized using ZnO seeded growth hydrothermal method and its properties as UV sensing.

PLoS One 2012 26;7(11):e50405. Epub 2012 Nov 26.

School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Nibong Tebal, Penang, Malaysia.

In this study, zinc oxide (ZnO) nanorod arrays were synthesized using a simple hydrothermal reaction on ZnO seeds/n-silicon substrate. Several parameters were studied, including the heat-treatment temperature to produce ZnO seeds, zinc nitrate concentration, pH of hydrothermal reaction solution, and hydrothermal reaction time. The optimum heat-treatment temperature to produce uniform nanosized ZnO seeds was 400°C. The nanorod dimensions depended on the hydrothermal reaction parameters. The optimum hydrothermal reaction parameters to produce blunt tip-like nanorods (770 nm long and 80 nm in top diameter) were 0.1 M zinc nitrate, pH 7, and 4 h of growth duration. Phase analysis studies showed that all ZnO nanorods exhibited a strong (002) peak. Thus, the ZnO nanorods grew in a c-axis preferred orientation. A strong ultraviolet (UV) emission peak was observed for ZnO nanorods grown under optimized parameters with a low, deep-level emission peak, which indicated high optical property and crystallinity of the nanorods. The produced ZnO nanorods were also tested for their UV-sensing properties. All samples responded to UV light but with different sensing characteristics. Such different responses could be attributed to the high surface-to-volume ratio of the nanorods that correlated with the final ZnO nanorods morphology formed at different synthesis parameters. The sample grown using optimum synthesis parameters showed the highest responsivity of 0.024 A/W for UV light at 375 nm under a 3 V bias.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0050405PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3506593PMC
May 2013

The effects of size and synthesis methods of gold nanoparticle-conjugated MαHIgG4 for use in an immunochromatographic strip test to detect brugian filariasis.

Nanotechnology 2012 Dec 19;23(49):495719. Epub 2012 Nov 19.

School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia.

This study describes the properties of colloidal gold nanoparticles (AuNPs) with sizes of 20, 30 and 40 nm, which were synthesized using citrate reduction or seeding-growth methods. Likewise, the conjugation of these AuNPs to mouse anti-human IgG(4) (MαHIgG(4)) was evaluated for an immunochromatographic (ICG) strip test to detect brugian filariasis. The morphology of the AuNPs was studied based on the degree of ellipticity (G) of the transmission electron microscopy images. The AuNPs produced using the seeding-growth method showed lower ellipticity (G ≤ 1.11) as compared with the AuNPs synthesized using the citrate reduction method (G ≤ 1.18). Zetasizer analysis showed that the AuNPs that were synthesized using the seeding-growth method were almost monodispersed with a lower polydispersity index (PDI; PDI≤0.079), as compared with the AuNPs synthesized using the citrate reduction method (PDI≤0.177). UV-visible spectroscopic analysis showed a red-shift of the absorbance spectra after the reaction with MαHIgG(4), which indicated that the AuNPs were successfully conjugated. The optimum concentration of the BmR1 recombinant antigen that was immobilized on the surface of the ICG strip on the test line was 1.0 mg ml(-1). When used with the ICG test strip assay and brugian filariasis serum samples, the conjugated AuNPs-MαHIgG(4) synthesized using the seeding-growth method had faster detection times, as compared with the AuNPs synthesized using the citrate reduction method. The 30 nm AuNPs-MαHIgG(4), with an optical density of 4 from the seeding-growth method, demonstrated the best performance for labelling ICG strips because it displayed the best sensitivity and the highest specificity when tested with serum samples from brugian filariasis patients and controls.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1088/0957-4484/23/49/495719DOI Listing
December 2012

Direct formation of gold nanoparticles on substrates using a novel ZnO sacrificial templated-growth hydrothermal approach and their properties in organic memory device.

Nanoscale Res Lett 2012 Oct 10;7(1):563. Epub 2012 Oct 10.

School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Nibong Tebal, Penang 14300, Malaysia.

This study describes a novel fabrication technique to grow gold nanoparticles (AuNPs) directly on seeded ZnO sacrificial template/polymethylsilsesquioxanes (PMSSQ)/Si using low-temperature hydrothermal reaction at 80°C for 4 h. The effect of non-annealing and various annealing temperatures, 200°C, 300°C, and 400°C, of the ZnO-seeded template on AuNP size and distribution was systematically studied. Another PMMSQ layer was spin-coated on AuNPs to study the memory properties of organic insulator-embedded AuNPs. Well-distributed and controllable AuNP sizes were successfully grown directly on the substrate, as observed using a field emission scanning electron microscope followed by an elemental analysis study. A phase analysis study confirmed that the ZnO sacrificial template was eliminated during the hydrothermal reaction. The AuNP formation mechanism using this hydrothermal reaction approach was proposed. In this study, the AuNPs were charge-trapped sites and showed excellent memory effects when embedded in PMSSQ. Optimum memory properties of PMMSQ-embedded AuNPs were obtained for AuNPs synthesized on a seeded ZnO template annealed at 300°C, with 54 electrons trapped per AuNP and excellent current-voltage response between an erased and programmed device.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/1556-276X-7-563DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3526390PMC
October 2012

Overview of the main methods used to combine proteins with nanosystems: absorption, bioconjugation, and encapsulation.

Int J Nanomedicine 2010 Feb 2;5:37-49. Epub 2010 Feb 2.

Nanobiotix, 60 rue de Wattignies, Paris, France.

The latest development of protein engineering allows the production of proteins having desired properties and large potential markets, but the clinical advances of therapeutical proteins are still limited by their fragility. Nanotechnology could provide optimal vectors able to protect from degradation therapeutical biomolecules such as proteins, enzymes or specific polypeptides. On the other hand, some proteins can be also used as active ligands to help nanoparticles loaded with chemotherapeutic or other drugs to reach particular sites in the body. The aim of this review is to provide an overall picture of the general aspects of the most successful approaches used to combine proteins with nanosystems. This combination is mainly achieved by absorption, bioconjugation and encapsulation. Interactions of nanoparticles with biomolecules and caveats related to protein denaturation are also pointed out. A clear understanding of nanoparticle-protein interactions could make possible the design of precise and versatile hybrid nanosystems. This could further allow control of their pharmacokinetics as well as activity, and safety.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2819905PMC
February 2010
-->