Finals

1.0 Introduction There has been a surge of interest in the understanding and application of the unique chemical and physical properties of materials with sizes in the 1-100 nm size range, which include individual structures such as clusters, nanoparticles, nanocrystals quantum dots, nanowires, and nanotubes as well as the collection of these individual structures into twoand three-dimensional assemblies.1 Nanomaterials, particularly nanoparticles, are too small to act like bulk solid but too big to behave like atoms. Thus, they represent the transition form between single atom or molecule and continuous bulk media and are therefore of primary interest for basic research. Nanoparticles received a special attention to the world of science because of their good potential for making new analytical tools for biotechnology and life sciences. On the other hand, use of the anomalous properties of nanoparticle provides a way for researchers to create new devices and technologies that have a wide range of potential applications. In this study, the silver metal will be the focus metal nanoparticles. Silver is one of the oldest subjects of investigation in science and technology, its regeneration leads to an increasing number of researches, especially to the world of nanotechnology and nanobiotechnology. Silver nanoparticles, also known as silver colloids are the most stable nanoparticles,2 since they display a wide variety of attractive aspects because of their self-assembly, surface science, the growth behavior of the individual particles, its size-related electronics, optical and magnetic properties, and their application to biomedical engineering. It was estimated before that the highest commercialization of nanoparticle was on Ag nanoparticles. Their application to the treatment of diseases is of big importance since nanoparticles are able to target specific cells or organs. Recently, this Ag colloid was used for food and clothing industry.3 As we all know, nanoparticles, especially the silver metal, has electrochemical and optical sensors due to its small size and controllable dimension. In order to have a stable nanoparticle, there are two certain requirements to have. First, the synthesis of nanoparticle should be water dispersible in a concentrated aqueous media in order to obtain an extensive

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conjugation to the desired molecule. Second, an efficient transfer of colloid to the media in question is required in order to have a good assembly of the conjugates after the nanoparticle is synthesized. The present study will focus on silver nanoparticle attached to a biomolecule. Its synthesis and characterization will be proposed in this paper. The application will also be tackled and the importance of Ag nanoparticle functionalized with biomolecule will also be discussed.

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2.0 Review of Related Literature 2.1 Synthesis of Metal Nanoparticles 2.1.1 Au Nanoparticles Gold nanoparticles stabilized by thiol functionality are extraordinarily stable and are therefore of a great system for studying nanostructure formation. These metal nanoparticles have many applications, for example, as stains in biological systems. They are also easy to synthesize, they have been intensively studies in recent years. A commonly used synthetic method involves the reduction of a gold salt in the presence of capping agent molecules such as thiols, citrates, or phosphines. The functionalities of these capping agents can be altered to yield various chemical properties. 4 2.1.2 Cu Nanoparticles Synthesis of well-dispersed Cu nanoparticles has been achieved by reduction of aqueous copper chloride solution using NaBH4 in nonionic water-in-oil (w/o) microemulsions formed by Triton X-100, n-hexanol, cyclohexane, and water.5 Rather than producing copper oxide in aqueous solution, the experiment showed that metallic Cu particles were formed without microemulsion because of the high local Cu concentration in an aqueous pool of microemulsion. The absorption spectrum of the colloidal Cu particles obtained in microemulsions does not exhibit the plasmon peak characteristics of the Cu surface. It is conceivable that the lack of the plasmon absorption band is attributed to the formation of a CuCl monolayer on the Cu nanoparticles. 2.1.3 Ni Nanoparticles In the presence of SDS-PVP clusters, Ni nanoparticles are obtained by reduction of nickel chloride with NaBH4.6 The interaction of nickel ions with sodium dodecyl sulfidePVP (SDS-PVP) clusters indicates the template function of the SDS-PVP clusters. From the experiment, it shows that the dispersion and average size of spherical Ni nanoparticles can be controlled by mediating the SDS-PVP clusters. The clusters the experiment were studied via surface tension and UV-Vis spectrophotometry. The Ni ion associates onto the headgroup of the SDS-PVP clusters by electrostatic interaction when the Ni nanoparticles are formed from reduction. PVP was adsorbed onto the particle surface to prevent agglomeration and the stabilization of the nanoparticles.

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2.1.4 Fe Nanoparticles Iron nanoparticles have been synthesized the by a one step thermohydrolysis of nitrate iron (III) solutions. The microwave system was designed by the authors to be able to induce very fast heating rates within an autoclave.7 The use f microwave oven is one fo the methods researchers now use to synthesize nanoparticles due to its fast heating rate and controllable heating power. Different nanoparticle sizes and shapes were prepared using the technique. 2.2 Synthesis of Silver Nanoparticles Use of direct laser irradiation has been reported for the fabrication of Ag nanoparticle having a well-defined size and shape distribution in solution.8 In that study, Ag nanoparticles were produced using an aqueous Ag salt solution and a surfactant in the absence of a reducing agent. A polyol-based process has also been used to synthesize spherical Ag nanoparticles having various size distributions.9 Two variations of the process were used to investigate the influence of reaction parameters such as temperatures and solvents on the resulting nanoparticle size distribution. The first method was the heating method wherein a solution containing Ag nitrate was heated to the reaction temperature. Here, the ramping rate was determined to be a critical parameter affecting the particle size. The second method was the injection rate method. Here, a silver nitrate aqueous solution was injected into hot ethylene glycol. Rapid nucleation led to the production of the nanoparticles. The Ag nanoparticles produced at an injection rate of 2.5 mL/s and a reaction temperature of 100 ºC have sizes ranging from 15-20 nm. The injection rate and the reaction temperature were found to be important factors in terms of reducing the particle size and attaining monodispersity for this particular method. PVP-coated Ag nanoparticles have been synthesized by the polyol method using glycerine as both reducing agent and solvent.10 In this method, a metal precursor is dissolved in a liquid polyol in the presence of a capping agent such as polyvinyl pyrrolidone (PVP), which was completely dissolved at high temperature. PVP is a linear polyer and stabilizes the nanoparticle surface via bonding with the pyrrolidone ring. The polymer’s concentration was found to play an important role in determining the nanoparticle size and shape.

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Monodisperse samples of Ag nanocubes have been synthesized in large quantities by reducing Ag nitrate with ethylene glycol in the presence of PVP. These cubes are single crystals and are characterized by slightly truncated shape bounded by {100}, {110}, and {111} facets.11 The presence of PVP and the molar ration of the PVP repeating unit to AgNO3 were found to influence the geometric shape and size of the Ag nanoparticles. Nearly cubic-shaped Ag nanoparticles have also been obtained by spin-coating colloidal nanoparticles on a glass substrate.12 Another method that is widely used to synthesize Ag nanoparticles is through solution-phase chemical reduction of metal salts. Typically, the metal precursors (AgNO3) are dissolved in a solvent containing stabilizing reagents. The reducing agent, such as borohydride, hydrogen, or citrate is added or generated in-situ in an aqueous solution of the metal salt. In the case of non-aqueous systems, the reducing agent can also be the stabilizing agent.13 In at least one case, the addition of NaCl solution to the Ag metal salt solution has been shown to enhance the formation of nanoparticles.14 In addition to the studies of synthesizing Ag nanoparticle, another method of synthesis had been done through the use of microwave oven. Microwaves have been used to control the dimension of the Ag nanoparticles being produced. The main advantage of using microwave for the preparation of Ag nanoparticle is the reaction rate, which distinctly higher than in the case of conventional heating. In addition, microwave heating is not only quick but also uniform. A polyol process that uses microwave has been investigated for the synthesis of several nanophase metals uner different condition from 100 ºC to 200 ºC. The synthesis was carried out at 100 ºC and 150 ºC in the presence of ethylene glycol, PVP, dodecyl amine, and oleic acid or trioctylphosphine to determine whether particle size and shape can be controlled. The Ag nanoparticle size was controlled using different capping agents. In addition, polychrome Ag nanoparticles have been prepared by a soft solution approach under microwave irradiation using a solution of AgNO3 in the presence of PVP without any reducing agent.15 The use of PVP has led to well defined Ag nanoparticle in the range of about 30-50 nm. Morphologically well-defined nanophase metals of Fe, Co, and Ni have been produced in the presence of PVP and dodecyl amine, while the use of just PVP or PVP and trioctylphosphine did no yield such particles. Moreover, Ag nanoparticle-sized cubes have

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been synthesized via reduction of Ag nitrate using PVP as capping reatgents, a reagent used to prevent reactive site from forming at the chain end of a molecule, may be used to prevent agglomeration of nanoparticles.16 These results showed that a variety of well defined nanophase metals can be produced using the microwave-polyol process in the presence of a metal capping agent.17 The nature of the solvent turned out to be one of the determinants of nanoparticle size and shape. For example, water, alcohols, DMF, and ethylene glycol have high dielectric losses and high reduction ability. Therefore, they are ideal solvents for microwave-induced nanoparticle synthesis. With microwave heating, the solvents and reagents are able to react faster to form the desired Ag nanoparticles. Samples of single crystalline polygonal plates, sheets, rods, wires, tubes, and dendrites have been prepared within a few minutes under microwave heating.18 Changing various experimental parameters, such as the concentration of metallic salt, surfactant polymer, chain length of the surfactant polymer, solvent, and reaction temperature could control the morphologies and size of nanostructures. In general, nanostructures with smaller sizes, narrower size distributions, and a higher degree of crystallization have been obtained under microwave heating than those in conventional oilbath or water heating. 2.3 Other Nanoparticle Synthetic Methods Nanoparticles have also been prepared using tip-directed scanning probe microscopy techniques19 and deposition techniques onto nanotemplates.20 A double-pulse electrochemical technique has been used to prepare Ag nanoparticles, the size, density, and dispersity of the nanoparticles being sensitive to the pulse parameters.21 Nanoparticle geometries such as triangles,22 nanoring,23 and nanoshells24 have also been synthesized previously. In the case of composite nanoparticle, anatase TiO2 nanoparticles doped with various dopants such as Nd3+, Pd2+, Pt4+, and Fe3+ have been synthesized using chemical vapor deposition.25 TiO2 nanoparticles have also been prepared using techniques such as impregnation,26 co-precipitation,27 sol-gel,28 and hydrothermal method.29

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2.4 Silver nanoparticle Functionalized with Biomolecule Attaching of Silver nanoparticle to phospholipids was made possible in an experiment.30. The researchers aimed to develop a mechanism on how to attach the silver nanoparticle to a phospholipid bilayer. The researchers were able to make simple two-step approach to functionalize the silver nanoparticle with phospholipid bilayer by using the presence of sulfur-hydrogen functionalities which also increased the free electron density of the silver nanoparticle. It was shown in the UV-Vis and IR spectra that there is a strong interaction between Ag-S which leads to the connection of the sulfur to the bilayer. In the study, the researchers were able to propose a method to functionalize the nanoparticle with biological molecules. Another research on attaching a biomolecule onto the silver nanoparticle can be found in the literature.31 The objective was to make a hybrid of Ag nanoparticle with controlled sizes and be electrodeposited on a glassy carbon electrode via the reduction of silver with the help of the DNA. The researchers were able to make the Ag nanoparticleDNA hybrid. The hybrid was able to demonstrate a good size distribution and a catalytic ability to reduce H2O2 and dissolved oxygen, thus produce good sensitivity for rapid detection of H2O2 in the absence of Oxygen. The researchers were also able to show that the presence of DNA with the colloid reduced the aggregation of the nanoparticle. Based on the good catalytic ability of the hybrid nanoparticles, the researchers were able to make a biosensor with high sensitivity. The method done for the experiment was compared to other electrochemical deposition methods. It showed that the proposed method is effective in preparing well-dispersed nanoparticles with modified functional surface. In addition to the studies mentioned above, another research about Ag colloids functionalized with a biomolecule that is found to be pH dependent and was used to monitor chemical activity of the biomolecule.32 The aim of the study was to attach 2aminothiophenol, a biomolecule to Ag nanoparticle. The authors had able to functionalized the silver colloid and were able to demonstrate the pH sensing application of the functionalized Ag nanoparticle based on the surface enhance Raman scattering. The pH dependent molecule enabled the researchers to sense the pH over the range of 3.0 – 8.0.

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The study also demonstrated that the nanoparticle can be used as a probe for delivering chemical information from biological media and have also provided a new way to monitor chemical transformation at the cellular level. In addition to the studies about coupling of Ag nanoparticle with a biomolecule, another study was done about the attaching of biological enzyme with a nanoparticle. 33 The authors’ objective on this study was to amplify the signal of electrochemical DNA based on the biocatalytic deposition of silver nanoparticles and silver enhancement methods. The coupling of the biological enzyme and the Ag nanoparticle makes the immunoassay ultrasensitive, which is more favored compared to other metal nanoparticles. It was shown in the research that once a Ag nanoparticle binds with a biological molecule, this biological molecule will have a great electrochemical properties that is amplified from the molecule. The approach of the researchers also showed that the strategy of the proposed study was to achieve lower detection limit for bioassays. 2.5 Silver nanoparticle Coupled with Polymers Strong resonant coupling with light and plasmons of Ag nanoparticle lead to huge number of amazing and technologically important optical effects, one of resonant coupling with light and plasmons is the enhancement of fluorescence from a nearby molecule. A research about Ag nanoparticle attached to a polymer using metal-enhanced fluorescence technology.34 The researchers’ objective is to produce a method to synthesize silver-deposited polycarbonate film based on fluorescence detection with enhanced sensitivity. In the study, polycarbonate was chosen as the polymer of interest due to its widespread use in biotechnology. The researchers were able to deposit the Ag nanoparticle to the polymer using UV radiation. The researchers used polycarbonate polymer instead of glass substrates for metal-enhanced fluorescence technology since polycarbonate films are suitable and cheap. Another report about Ag nanoparticle coupled deposited in a polymer. According to the study, polyaniline is one of the most conducting polymers because of its potential

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application such as batteries, electrochromic devices, chemical sensors, and biosensors.35 The authors’ objective in the study was to prepare and characterize oligoaniline derivative nanofiber containing silver nanoparticles. In the experiment polyvinylpyrrolidone (PVP) was used to immobilize the nanoparticle and the polymers as the reducing agent for Ag+ in the PVP solution. Using electrospinning technique the said silver nanoparticle with polymer was synthesized by the researchers. The morphology of the hybridized nanocomposites and the distribution of Ag nanoparticles were characterized by scanning electron microscope and transmission electron microscope. 2.5 Interaction of Ag Nanoparticles with Diseases The interaction of metal nanoparticles, specifically silver, with biomolecules and microorganisms is a growing field of study. Many areas of research have exploring the possibilities of Ag nanoparticles curing or inhibiting some diseases. A res36earch about Ag colloids inhibiting HIV-1 and therefore causing the cell to commit apoptosis. The authors’ aim on this study was to bind the Ag nanoparticles with the HIV-1 so the virus will be inhibited and therefore lead to apoptosis. The researchers were able to synthesize a silver nanoparticle with the size ranging from 1-10 nm. The synthesized colloid was bound to the virus through the attachment of gp120 glycoprotein knobs. The exposed sulfur-bearing residues of the glycoprotein knob of the virus make it an attractive site to the Ag nanoparticles. The authors have shown that the interaction of Ag nanoparticles with HIV-1 is really possible and were able to demonstrate that once the colloids were attached to the virus, the silver nanoparticle inhibits the virus from attaching to the host cells. Due to silver’s antiseptic properties to several bacteria, including the famous E. coli, another study about Ag nanoparticle interacting with microorganisms.37 The objective was to synthesize a cheap and environmental friendly Ag nanoparticle that has the ability to kill bacteria. The researchers of the project were able to synthesize Ag nanoparticle through oxidation technique. After the nanoparticle was produced the researchers incubated E. coli bacteria overnight on a plain glass slide coated with silver nanoparticle and on a glass slide

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without the silver nanoparticle. The authors found out that all the bacteria were killed on the glass with the silver nanoparticles and the bacteria without the colloids increased in number. As a result, the authors confirmed that the nanoparticles are toxic to bacteria. The authors have demonstrated that Ag nanoparticles interacted with the outer membrane, causing structural changes which lead to structural degradation of the microorganism and eventually apoptosis of the cell of the bacteria. In addition to the studies mentioned about the interaction of silver nanoparticle with microorganisms, another study of the silver colloid as an antimicrobial agent.38 The purpose of the study was to show the antimicrobial activity of silver nanoparticle. The silver nanoparticle’s unique chemical and physical properties were used in the experiment as an alternative for the development of new antimicrobial agent. It was shown that once the Ag nanoparticle contacted with the moisture, the silver gets ionized. The researchers have shown that the silver ion binds to tissue proteins and brings structural changes in the bacterial cell wall and nuclear membrane which will lead to cell distortion and death. They have also shown that the silver ion binds to bacterial DNA and RNA by denaturing and stops bacterial multiplication. The researchers proposed a possible mechanism of silver that seems to kill all the bacteria it gets contact with. The silver nanoparticles or the silver ions interact with the thiol group compounds found in the respiratory system of the bacteria. Then silver binds with the cell wall and membrane and inhibits the respiration process which again leads to cell death of the bacteria. However, despite the fact that Ag nanoparticles have many uses in the environment such as antimicrobial agent, biosensors, and virus killers, it was reported that Ag nanoparticles can damage DNA in mammalian cells.39 The authors’ objective in this study was to examine the DNA damage response once the cell is exposed to silver nanoparticle. The authors of this research expose the DNA of mouse embryonic stem cells and fibroblast to polysaccharide surface functionalized and non-functionalized Ag nanoparticle. In the article, p53 was introduced as the master guardian of the cell and is able to activate cell cycle checkpoints, DNA repair, and cell death response to maintain genomic stability. It was shown that both types of silver nanoparticles mentioned earlier normalized the cell

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cycle checkpoint p53. It was shown that in the absence of cell stress of DNA, p53 concentration was low but in the presence of the silver nanoparticle, the concentration of p53 became high. Therefore, the expression of p53 protein in two types of mammalian cells by Ag nanoparticles exposure suggested that p53 protein could be a molecule marker to assess the genetic nanotoxicity. The observation of the researchers also suggested that the different surface chemistry of silver nanoparticles induced different damage to DNA, the coated silver colloid showed more severe damage that the uncoated Ag nanoparticle. The observations also showed that polysaccharide functionalized nanoparticle are much distributed compared to the non - functionalized Ag nanoparticle since agglomeration happens and limits the surface area distribution and also limits the access of the particle to membrane bound organelles. 2.6 Ag Nanoparticle Used as Biosensors to Biomolecules During the recent years, scientific interest has been raised by the discovery of different nanoparticles. One of these nanoparticles is the Ag nanoparticles due to its good conduction of electricity and its ion can easily combine with many biological compounds through electrovalent bond or coordinate bond. Ag nanoparticle can be also easily absorbed in an electrode which turns to easily catalyze reduction – oxidation processes. This certain kind of property of silver makes it a good biosensor for biological molecules. A research on Ag nanoparticle was used as biosensor for cysteine. 40 The objective of the research was to study the electrochemical behavior of Ag nanoparticle functionalized with mercury film glassy carbon electrode. The functionalized nanoparticle on this research was devised as a biosensor to study the catalytic activity of the electrochemical response of cysteine, an amino acid which exhibits irreversible oxidation and requires positive overpotential to most electrode surfaces for the electrochemical detection activity of the molecule. In the study, a silver nanoparticle was synthesized according to literatures. The mercury film electrode was dipped into the prepared silver colloid for 2 days at room temperature to make the doped electrodes. The constructed electrode in the study was dipped into an acetated buffer solution containing certain concentration of cysteine. It was demonstrated that the cysteine molecule was absorbed since the size of the electrode

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increased in diameter. To test the electrochemical response of cysteine, the mercury film glassy carbon electrode without the Ag nanoparticle was made and dipped into the cysteine solution. It shows that using cyclic voltameter the one without the Ag colloid gives low redox peaks. In contrast with the one with Ag nanoparticle electrode, it showed a pair of reversible and more sensitive redox peaks, which also shows the reduction and oxidation peaks have the same height. The behavior of the peaks showed that Ag nanoparticle doped in mercury film could catalyze the electrochemical reaction of cysteine. The authors have demonstrated that when silver nanoparticles are attached to an electrode it can best work for the determination of electrochemical activity of biomolecules and therefore can act as a new biosensor. Another research about Ag colloid used as biosensor for DNA using electrochemical detection was found.41 The objective of the study was to develop an electrochemical detection method for biological assay for detecting DNA hybridization based on the precipitation of silver onto gold nanoparticle DNA labels. For the electrochemical detection of DNA hybridization based, the added silver nanopraticles with the gold nanoparticle label on it enhances the properties of the gold metal. One of the facts of this research was on gene analysis and mutant detection. The authors of the study demonstrated that when a silver-enhanced colloidal gold is used the sensitivity of the biosensor increased by about two orders of magnitude compared with the one with out the silver when differential pulse voltammetry was used to measure the signal of the DNA hybridization. To add to the studies about Ag nanoparticle used as a biosensor, another report on Ag nanoparticle used to improve a biosensor to detect glucose. 42 The objective of the study was to use Ag nanoparticle to enhance the sensitivity of the glucose biosensors based on the immobilization of glucose oxidase. The glucose oxidase was mixed with the silver colloid and coated onto a platinum electrode with polyvinyl butyral (PVB) and glutaraldehyde by sol-gel process. The researchers studied the effect of Ag nanoparticle on the sensitivity response of glucose biosensor by electron micrograph. Two media were prepared, one with Ag nanoparticles and one without. The other parameter that was used in the experiment

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was to employ a hydrophobic and hydrophilic Ag nanoparticle onto to the glucose biosensor.

The authors showed that response of the electrode containing Ag colloid

increased compared to the one without. The results showed that the response of the electrode containing the hydrophobic Ag nanoparticle was much greater compared to the electrode containing the hydrophilic Ag nanoparticles. The authors also demonstrated that Ag nanoparticle functioned as an electron-conducting pathway between the prosthetic groups and the electrode surface, thus the electron transfer rate between glucose oxidase and the electrode increased significantly.

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3.0 Proposal Cancer detection and treatment has been the interest of most of the researchers due to its fast rate of proliferation in the human body. The inherent difficulty of isolating cancer cells due to its almost similar structure to human cell has been the challenge for researchers in this field. The application of the drugs and as much as radioactive compounds post the problem of selectivity of the action on cellular destruction of the cancer cells. Other chemical compounds also are non selective in their action thus creating variety of side effects. However, the fast and emerging field of materials science opens vast possibilities of manipulating materials that could have beneficial medical applications. Particularly, nanotechnology has been found to have more than just electronics application but instead a very useful tool in the medical science and on the treatment and management of diseases. Aside from the direct application of nanoparticles in disease treatment such as antimicrobial properties of metal nanoparticles. Other novel techniques are introduced to even diversify the applications of these materials. New materials find its application from optics, to magnetic as far as sonics. This study exploits the possibilities that these disciplines could offer in the design of a new material that will improve the diagnosis, treatment and management of certain cancer diseases. With the advent of medical physics, the applications of the magnetic properties of matter allowed the development of magnetic resonance imaging technology which then improves the visual diagnosis of the patient’s disease. Here we propose the use of magnetite as a binding molecule that will allow the detection and attachment of the nanoparticle in the cancer cell. However, the inherent difficulty of allowing the magnetite

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to increase its retention time in the human system and maintaining selectivity is an issue that needs to be addressed. The group proposes the incorporation of the magnetite in a hydrophilic polymer such as polyethylene glycol to allow increase in circulation of the magnetite in the system to allow exploration of to most part of the human body. This will thus be the composition of a fraction of what the surface of the nano particle would be made of. It is also a concern of the group that surface poisoning would eventually hinder the molecule of even reaching the site of binding interest. It is then proposed that the surface of the magnetite be then encapsulated with silver shell which will protect the active sites of the magnetite from ions and proteins that might bind with it. The preparation of the magnetite is described.43 Other studies describe that the most efficient means of synthesizing magnetic nano particles/crystals is by reverse micelle process.44,45 More recent research however describes a modified micellar means of synthesizing the nanoparticle with functional groups attached to it.46 For the purpose of this study, we shall use rather the reverse micelle process. 3.1 Synthesis of the magnetite nanocarrier of drug Optimal size and distribution of nanoscale magnetite is made possible to be synthesized in a nanoreactor.47,48,49,50 This method employs two separate microemulsion preparations. The first microemulsion involves oil base which is comprise of isooctane and uses a surfactant of diiso-octylsulphoccinate (AOT). This microemulsion specifically contains 2 mL 30% NH4OH + 2.4 mL water, + 66 mL 0.50 M AOT isooctane. The second type of microemulsion is composed of 0.576 g FeSO4*7H2O made to dissolve in 8 mL H2O and 66 mL AOT isooctane. Both systems were sonicated for 10 minutes. The two

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emulsions were stirred mechanically for a period of 75 minutes at temperature of 50 oC. The first system uses NH4OH as precipitating agent. The precipitation of Fe3O4 is shown by the following: 3FeSO4 * 7H2O + 6NH4OH + ½O2  Fe3O4 + 3(NH4)2SO4 + 24H2P The resulting mixture is then treated with methanol to allow separation of surfactant. The resulting solid is then washed with methanol-acetone-water, which was then dried over an oven for 30 minutes at 90 0C. 3.2 Surface Functionalization of Magnetite Surface functionalization modifies the hydrophobic nature of the magnetite making it more susceptible for drug conjugation. Bifunctional methyl 3-mercaptoproprionate (HSCH2CH2COOCH3) attaches itself with the magnetite thru the Fe-S bond. Another inherent problem is how to attach the magnetic nanoparticle with the anti-cancer drug. Or make the drug acceptable for attachment with the nanoparticle. This is made possible by changing the –OCH3 to –NHNH2 via hydrazinolysis since –NHNH2 conjugates with the antitumor drug, doxorubicin. These hydrazones are found to be stable at relatively neutral environment such as pH 7.00. However, the hydrazone link at pH relatively around 5.005.50, which is a similar pH in the endosomes/lysosomes of cancer cells, hydrolyzes thus releasing the active pharmaceutical ingredient doxorubicin.51,52 The said antitumor drug conjugates to the surface of the functional groups of the magnetite by linking the hydrazone to the carboxyl group of doxorubicin. There have been other drug delivery techniques reported which utilizes polymers which encapsulates the nano crystal/particle where upon exposure to high temperature will cause its decomposition thus releasing the anti-cancer drug.53 This study however,

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introduces the use of silver nanoparticle as coating material as a means of protecting the magnetite and doxorubicin from premature reaction and poisoning. It is then suggested that the encapsulation of the functionalized magnetite by silver nanoparticle be done adopting the method already reported for coating individual magnetite with silver nanoparticle.54 3.3 (Fe3O4)core–Agshell Nanoparticles Each of the Fe3O4 particles are coated separately by the metal silver to preserve the magnetic property of the particle for a considerable amount of time. This is done by silver sulphate was added with Fe3O4 in a molar ratio of 0.5:1 in a 0.5 g of glucose. These were then sonicated for 15 minutes and then heated with stirring over a water bath for an hour. The completeness of the reaction is qualitatively detected by the browning of the originally black iron oxide. The particles were then centrifugated and separated from the clear solution. Upon diffusion in the human body, the drug delivery device (DDD) enters the cancer cell. The conditions inside the cancer cell activate the release of doxorubicin making the release to be highly specific. The location of the tumor cells are located by the use of magnetic resonance imaging. Upon locating nano optics will irradiate the site to which most of the DDD are concentrating. Laser desorption/ionization of Ag is capable of producing both positively and negatively charged silver clusters up to 100-mer.55 A pulsed nitrogen laser capable of producing a wavelength of 337 nm for MALDI and TOF using a delayed-extraction mode was used. The application of laser on magnetite coated with silver nanoparticle will desorbed the silver by ionising the silver particles. The desorpted silver is expected to be chelated by the carboxyl group and by the azide group. Making the silver

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cation still attached to the DDD. The deprotected magnetite will then attach itself to the tumour cells. Magnetic agitation of the magnetite will create sufficient amount of thermal energy that would even augment destruction of the cancer cells.56 It is even explored the possibility of mobilizing and concentrating to a particular site the tumour cells with the aide of a magnet making the intervention of removing the cancer cell debris less invasive

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