Determination of Gold Nanoparticle Sizes

Determination of Gold Nanoparticle SizesDaron ChuaSynopsisIn this experiment, the objectives of this experiment was to understand the diverse applications of luxurious nanoparticles and to synthersize Colloidal property nanoparticles by liquid chemical method.Z-average of nanoparticles for the carminedish resultant and the greyish event was 60.86 and 50.40 respectively. However it was noted that there were impurities in the result hence expungeing the Z-average. As such, the people of color of the solution and the Z-average did not tally.It was discove cherry that by adding salt into the solutions there will be colour alter. This is due to NaCl aggregating the nanoparticles together. This causes the nanoparticles to absorb the red straighten out hence reflecting the solution in a more puritanical colour.Other methods of forming golden nanoparticles and a diverse application for gold nanoparticles were noted.IntroductionThe objectives of this experiment was to understand t he diverse applications of gold nanoparticles. Colloidal gold nanoparticles were synthesized by means of liquid chemical method.TheoryLiquid Chemical methodMost of the gold nanoparticles are produced in a liquid (liquid chemical methods) byreduction of hydrogen tetrachloroautate (HAuCl4). By dissolving HAuCl4, the solution is rapidly stirred while a reduce agent is be added. This causes Au3+ ions to be cut down to neutral goldatoms. As more and more of these gold atoms form, the solution becomes supersaturated, and gold gradually starts toprecipitatein the form of sub-nanometer particles. The rest of the gold atoms that form stick to the existing particles, and, if the solution is stirred vigorously enough, the particles will be fairly uniform in size showing the solution as red.To prevent the particles from aggregating, some sort of modify agent that sticks to the nanoparticle surface is usually added. Also, gold colloids deal be synthesized without stabilizers bylaser ablati onsin liquids. They can be functionalized with various organic ligands to create organic-inorganic hybrids with advanced functionality.Several methods that revolve about this idea are Turkevich method, brust method and perrault method, etc.Gold NanoparticlesColloidal goldis a suspension particles ofgoldin a fluid, usually water. The liquid is usually either an intense red colour (for particles less than 100nm) or blue/purple (for larger particles).As particle size increases, the wavelength of surface plasmon resonance related absorption shifts to longer, redder wavelengths. Red rest is thusly absorbed, and blue light is reflected, yielding solutions with a pale blue or purple color. A change in temperature will also affect which the gold to be at a different energy band. The diameter of gold nanoparticles determines the Wavelength of light absorbed as shown on the diagram illustrated above.ProceduresStock resolvent0.1g of HAuCl4 was dissolved in 500ml distilled water to obtain 1 .0mM hydrogen tetrachloroautate.0.5g of Na3C6H5O7.2H2O (trisodium change state dehydrate) was dissolved in 50ml of distilled water to obtain 1% concentration.0.5g of NaCl was dissolved in 10ml of distilled water.Experiment20ml of 1.0mM HAuCl4 was added to a conical flask.The conical flask was placed in a stirring hot plate and a magnetic stir bar was added.2 samples were prepared. ace was stirred continuously even it was at boiling point. The other sample stopped stirring once it was boiled.2ml of 1% solution of trisodium citrate dehydrate was then added to the boiling solution. Gold Sol was gradually formed as citrate reduces the gold (III).Presence of a colloidal suspension was observed by the animadversion of a laser beam from the particles.The solution of both samples were being transferred to two test tubes.5 10 drops of 1M NaCl solution was added into one of the test tubes and the color change of the solution was being observed.The two solutions in the test tubes were bein g filtered with a 0.45 um syringe filter. The solutions were subsequently transferred into a sample holder.The Malvern Zetasizer Nano S Light scattering equipment was apply to measure the size of the nanoparticles in the two sample holder. (0.47 refractive index was used.)ResultsResults as follows Solution with spin even at boiling point glossary observed Reddish BrownSize of Gold nanoparticle 63.77 with 3 upsides roseola 1 41.1, Peak 2 433.2, Peak 3 3913Solution without spin at boiling point Colour observed Greyish / Bluish / ClearSize of Gold nanoparticle 53.31 with 3 peaksPeak 1 143.9, Peak 2 1.651, Peak 3 3213CalculationStandard Calibration67.54nm 63.63nm = 2.91nmSize of Gold nanoparticle (Reddish/Brown) Z-Average63.77nm 2.91nm = 60.86 nmSize of Gold nanoparticle (Greyish/Blue) Z-Average53.31nm 2.91 nm = 50.40 nmDiscussionFrom the results, Z average for the ruddy brown solution was calculated at 60.86nm, while the greyish/blue was calculated at 50.40nm.With refe rence to theory, the results concluded by Z-average is inaccurate. By right, anything at the blue shift is of a larger particle size. By reading off the highest intensity peaks of both graphs of red and blue solutions, size of particles were 41.1nm and 143.9nm respectively. Ideally 1 peak in the chart would be best.Other peaks that affected the Z-average were probably impurities. This error may be due to carelessness of assuming all equipments provided for the experiment were clean. and then there could be dirt or dust trapped whatsoever.In order to obtain even smaller particle sizes, adding of all solutions should have been through slowly, for example adding trisodium citrate drop by drop, allowing the droplet to fully react with the solution before adding in another. With that, the alloy part is no doubt the most significant process parameter of the experiment.Other factors that affect particle sizes are mixing time and temperature and concentration. Different temperatures with in the reaction will cause heat and wad transfer gradients. A low concentration of solution will yield too low of a result and lastly for our case, mixing time. Insufficient mixing time/stoppage of mixing will disallow the nanoparticles to disperse. Hence having a larger particle size.1. Explain the functions of trisodium citrate used in this experiment.In this experiment, Trisodium citrate acts as an reducing agent to reduce hydrogen tetrachloroautate in order to produce spheroidal gold paticles. In general, the greater the concentration and power of the reducing agent. The smaller the resultant gold particles in the suspension.2. Account for the colour change observed in step 4.6In step 4.6 of the practical booklet, NaCl solution is added into the solution causing a colour change. By adding NaCl into the solution, it causes the gold nanoparticle surface charge to turn neutral, causing the nanoparticle to aggregate. As a result the solution colour changes from red to black blue. A s for the greyish bluish solution, it turns to a even clearer solution.A larger particle size will cause absorption of the red light hence reflecting the solution as blue.3. State two other synthesis methods for gold nanoparticles beside the liquid chemical method.SonolysisOne method for the experimental generation of gold particles is by sonolysis. The process is based on ultrasound. It uses the reaction of an aqueous solution of HAuCl4withglucose. The reducing agentsare hydroxyl radicals and sugar pyrolysis radicals. The morphology obtained is that of nanoribbons with width 3050nm and length of several(prenominal) micrometers. These ribbons are very flexible and can bend with angles larger than 90. When glucose is being replaced by cyclodetrin (a glucose oligomer), only spherical gold particles are obtained.Block Copolymer-mediated MethodOther method for gold nanoparticles is by using a block copolymer.In this synthesis methodology, block copolymer plays the dual role of a reduci ng agent as well as a stabilizing agent.The formation of gold nanoparticles comprises three main stepsreduction of gold salt ion by block copolymers in the solution and formation of gold clusters,adsorption of block copolymers on gold clusters,and further reduction of gold salt ions on the surfaces of these gold clusters for the growth of gold particles in steps.This method usually has a limited-yield (nanoparticle concentration), which does not increase with the increase in the gold salt concentration. Recently a test has been done that by adding trisodium citrate in 11 molar ratio increases the gold formation by many gold.4. Cite some other application in addition to those mentioned under introduction.Electronics Gold nanoparticles are designed for use as conductors from printable inks to electronic chips. As the world of electronics become smaller, nanoparticles are important components in the chip design. Nanoscale gold nanoparticles are being used to connect resistors, conduct ors, and other elements of an electronic chip.Probe Gold nanoparticles are relatively dense, making them useful as probes for transmission electron microscopy.Catalyst Gold nanoparticles are used as catalysts in a number of chemical reactions. The surface of a gold nanoparticle can be used for selective oxidation or in certain cases the surface can reduce a reaction (nitrogen oxides). Gold nanoparticles are being developed for fuel cell applications. These technologies would be useful in the automotive and display industry.ConclusionIn conclusion, the experiment was not very successful as there were impurities in the solution. Hence the Z average was being affected. However objectives were met as colloidal gold was being synthesized and applications of gold particles were also understood.Referenceshttp//en.wikipedia.org/wiki/Colloidal_goldhttp//www.sigmaaldrich.com/materials-science/nanomaterials/gold-nanoparticles.htmlhttp//www.webexhibits.org/causesofcolor/9.htmlhttp//clustertwo .org/Shaowei Chen lectures/ roll up 2 lecture 2.pdfhttp//www.ivdtechnology.com/article/manufacturing-high-quality-gold-sol