Tuning the Size of Gold Nanoparticles with Repetitive Oxidation-reduction Cycles (original) (raw)

New analytical applications of gold nanoparticles

2009

Dissertation zur Erlangung des Doktorgrades der Naturwissenschaften (doktorum rerum naturalis, Dr. Rer. Nat.) der Fakultät für Chemie und Pharmazie der Universität Regensburg Deutschland vorgelegt von Fredy Kurniawan aus Surabaya, Indonesia im März, 2008 vi 6. Kesimpulan……………………………………………………………………… 7. References……………………………………………………………………… 8. Curriculum vitae ……………………………………………………………….. 9. List of publications and presentations……………………………………….. 10. Acknowledgements……………………………………………………………… Nanoparticles (1-200nm) have unique electronic, optical, and catalytic properties. Its properties is also connected to the method how to prepare nanoparticles to control the shape and size of nanoparticles, provide exciting building blocks for nanoscaled assemblies, structure, and devices. Miniaturization of structures by mechanic methods and electron-beam lithography is reaching the Smaller nanoparticles may be formed in the gas phase , or by ablation using high peak-power laser pulses 74,75 , while others have been etched , electrodeposited , or synthesized directly onto surfaces , or in Langmuir-Blodgett (LB) layers 81 . These techniques cater for the specialized needs of researchers who require colloids of particular sizes, shapes, or materials. For the cheap and easy synthesis of simple nanoparticles, there is no substitute for solution-state synthesis, which can be used to prepare bulk quantities without the need for specialized laboratory apparatus. Nanoparticles are important in a diverse set of fields, and they can generally be classified as two type i.e. engineered or nonengineered. Engineered nanoparticles are intentionally designed and created with physical properties tailored to meet the need of specific application. They can be end product in and of themselves, as in the case of quantum dots or pharmaceutical drugs, sensor for special purposes, or they can be component later incorporated into separate end products, such as carbon black in rubber products. Either way the particle's physical properties are extremely important to their performance or the performance of any product into which they are ultimately incorporated. Nonengineered nanoparticles, on the other hand, are unintentionally generated nanoparticles, such as atmospheric nanoparticles created during combustion. With nonengineered nanoparticles, physical properties also play importance role as they determine whether or not ill effect will occur as a result of the presence of these particles. For non analytical application nanoparticles based materials have been developed for drug and gene delivery 82 , tissue engineering 83 , tumor destruction 84 , separation and purification of biological molecules and cell 85 , and also -Phagokinetic studies 86 . Natural bone surface is quite often contains features about 100 nm across. If the surface of an artificial bone implant were left smooth, the body would try to reject it. So production of a fibrous tissue covering the surface of the implant is preferable to get smooth surface. This thin layer will reduce the bone-implant contact, which may result in loosening of the implant and further inflammation. Nano-sized features can help to get smooth surface. It was demonstrated the hip or knee prosthesis which Functionalized magnetic nanoparticles have found many applications including cell separation and probing 90 . Most of the magnetic particles studied so far are spherical, which somewhat limits the possibilities to make these nanoparticles multifunctional. Alternative cylindrically shaped nanoparticles can be created by employing metal electrodeposition into nanoporous alumina template 91 . Depending on the properties of the template, nanocylinder radius can be selected in the range of Major area of activity Technology Advectus Life Sciences Inc. Drug delivery Polymeric nanoparticles engineered to carry antitumour drug across the blood-brain barrier Alnis Biosciences, Inc. Bio-pharmaceutical Biodegradable polymeric nanoparticles for drug delivery This biosensor could be fabricated reproducibly, exhibiting fast amperometric responses (2.5 s) to H 2 O 2 , high sensitivity and long-term stability. The detection limit of the biosensor could attain 2.0 µM, and the linear range was between 5.0 µM and 10.0 mM. Another group 100 has also completed direct electrochemistry of cytochrome c on a novel electrochemical interface constructed by self-assembling AuNPs onto a three-dimensional silica gel network. In addition, some thiols with specific functions could also be assembled on the electrode surface. Thus, AuNPs could be immobilized on the self-assembly monolayer surface and complete the DET of some redox-proteins. For instance, Gu et al have reported the DET of hemoglobin on the citrated-capped AuNPs assembled on a cysteamine modified gold substrate 101 . Furthermore, they investigated the electrocatalytic activity of nanoparticle/ hemoglobin electrode towards H 2 O 2 reduction. As a result, a stable nanoparticle biosensor was constructed. In addition, the DET of glucose oxidase and horseradish peroxidase was well demonstrated by Pingarron and co-workers 96 and Chen 102 on AuNPs immobilized cysteamine modified gold electrode. The AuNPs modified carbon paste electrodes have provided a good microenvironment for completing the DET of different redox-proteins. For instance, Ju and co-worker 103 [95] reported that the DET between immobilized myoglobin and colloidal gold modified carbon paste electrode was completed. The myoglobin immobilized on the colloidal AuNPs displayed a pair of redox peaks in 0.1M pH 7.0 PBS with a formal potential of about -0.108V (versus NHE). Furthermore, the preparation of a xanthine oxidase biosensor, based on a carbon paste electrode modified with electrodeposited AuNPs, for the amperometric determination of hypoxanthine was reported by Pingarron group 104 . Our group synthesized a kind of gold nanoparticle protected by a synthetic lipid (DDAB). With the help of these AuNPs, hemoglobin could exhibit a DET reaction on DDAB protected AuNPs modified glassy carbon electrode 105 . In addition, the AuNPs modified ITO and screenprinted rhodium-graphite electrodes could be also developed to complete the DET of some redox-protein such as myoglobin 106 and cytochrome P450scc 107 . Recently, layer-by-layer (LbL) assembly technique based on electrostatic interaction 108,109 was suggested to be used to tailor the electrochemical interface for completing the DET of some redox-proteins and constructing novel electrochemical DNA marked paramagnetic beads. Differential pulse voltammetry was used for a direct voltammetric detection of resulting Au 67 quantum dot-target DNA/complementary DNA-paramagnetic bead conjugate on magnetic graphite-epoxy