Monthly Archives: March 2010

Gold Nanoparticles Cancer Treatment Blog

Gold Nanoparticles Cancer Treatment Blog

Gold Nanoparticles are emerging as promising agents for cancer therapy and are being investigated as drug carriers, photothermal agents, contrast agents and radiosensitisers. This review introduces the field of nanotechnology with a focus on recent gold Nanoparticles research which has led to early-phase clinical trials. In particular, the pre-clinical evidence for gold Nanoparticles as sensitisers with ionising radiation in vitro and in vivo at kilovoltage and megavoltage energies is discussed.

Gold Nanoparticles Cancer Treatment Blog

Gold Nanoparticles Cancer Treatment Blog

 

For this therapy to be effective, the gold Nanoparticles have to attach to a cancer cell more easily than a healthy cell, otherwise the laser pulse would damage healthy tissue. To accomplish this, the researchers coated the particles in an antibody that is known to attach to the specific type of aggressive cancer they were using in the study, head and neck squamous cell carcinoma. It is this antibody that attaches to the receptor at the cell membrane.

Preparing the Nanoparticles

The researchers also found that there was an optimal size to the gold particles. If the particles were less then 10 billionths of a meter (10 nanometers) in diameter, the cell would quickly clear them out. If the particles were greater than 100 nanometers the cell had trouble internalizing the particles. The scientists found that the Nanoparticles which worked best for their study were around 60 billionths of a meter in diameter.

Gold Nanoparticles Cancer Treatment Blog

Gold Nanoparticles Cancer Treatment Blog

 

These antibody-coated gold Nano spheres were found to insert themselves into cancer cells far more readily than healthy cells; the average cluster size in healthy cells was found to be 64 nanometers (about 1 sphere), while the average cluster size in cancer cells was found to be about 300 nanometers (about 100 spheres).

One natural advantage to this process is that tumors often have leaky vascular systems, so when the gold particles are injected intravenously near the known cancer, they rapidly spread and are incorporated throughout the cancerous region. The scientists noted that 24 hours of time was needed after the injections to allow gold clusters to form in the cells.

Blowing Up the Cancer Cell

Gold Nanoparticles Cancer Treatment Blog

Gold Nanoparticles Cancer Treatment Blog

 

Once the Gold Nanoparticles are incorporated into cells, the researchers exposed the tissue to a laser pulse (near infrared radiation of wavelength 782 nanometers) for a duration of 30 trillionths of a second (30 picoseconds). This particular type of laser light is optimal because it penetrates tissue well and it is not resonant with the gold Nanoparticles. This means that when the light strikes the Nanoparticles it does not absorb it and immediately start warming the bulk of the gold Nanoparticles resulting in overheating the cell. Rather, during the first 10 nanoseconds some melting of the surface without bulk heating of the gold nanoparticles2 occurs, and this vaporizes the fluid around the gold Nanoparticles. The vaporized fluid rapidly expands and then collapses. However, it is imperative to note that the effect is inconsequential unless there are tens of Nanoparticles in the cluster. The creation of a Nano bubble that rapidly expands and collapses, with enough energy to destroy a cell, is dependent on the number of gold spheres in the cluster, with the severity increasing as the cluster size increases.

Gold Nanoparticles Cancer Treatment Blog

Gold Nanoparticles Cancer Treatment Blog

 

This selectivity of severity with size is what keeps the healthy cells safe. The gold Nanoparticles don’t do well at transforming the laser pulse to thermal energy on their own, so any Nano bubbles formed are relatively insignificant—a few spheres together in a healthy cell will not cause any damage. It is the cluster of nanoparticles within the cancer cells that effectively converts the laser pulse to thermal energy, causing vaporization of the surrounding fluid, a rapid expansion, and a collapse, leading to the destruction of the cancer cell. This event is not easily detected by optical means, but it is easily “heard” by detecting the sound wave produced during the rapid expansion and collapse.

Nanoparticles are currently employed in several medical applications and many more have been suggested, with great potential benefits for patients and medical providers. Due to their high atomic mass, gold Nanoparticles can absorb significantly more radiation than soft tissue cells, making them ideal for boosting the radiation dose in tumors or enhancing contrast of specific tissues during diagnostic imaging (e.g. doping a tissue with 1% of its weight with Nanoparticles would double the radiation dose absorbed following kV X-ray exposure).

Gold Nanoparticles Cancer Treatment Blog

Gold Nanoparticles Cancer Treatment Blog

 

It has been almost 4 decades since the “war on cancer” was declared. It is now generally believed that personalized medicine is the future for cancer patient management. Possessing unprecedented potential for early detection, accurate diagnosis, and personalized treatment of cancer, nanoparticles have been extensively studied over the last decade. In this review, we will summarize the current state-of-the-art of gold nanoparticles in biomedical applications targeting cancer. Gold nanospheres, nanorods, nanoshells, nanocages, and surface enhanced Raman scattering nanoparticles will be discussed in detail regarding their uses in in vitro assays, ex vivo and in vivo imaging, cancer therapy, and drug delivery. Multifunctionality is the key feature of nanoparticle-based agents. Targeting ligands, imaging labels, therapeutic drugs, and other functionalities can all be integrated to allow for targeted molecular imaging and molecular therapy of cancer. Big strides have been made and many proof-of-principle studies have been successfully performed. The future looks brighter than ever yet many hurdles remain to be conquered. A multifunctional platform based on gold nanoparticles, with multiple receptor targeting, multimodality imaging, and multiple therapeutic entities, holds the promise for a “magic gold bullet” against cancer

Biomedical applications of gold nanoparticles: Cancer nanotechnology is an interdisciplinary area with broad potential applications in fi ghting cancer, including molecular imaging, molecular diagnosis, targeted therapy, and bioinformatics. The continued development of cancer nanotechnology holds the promise for personalized oncology in which genetic and protein biomarkers can be used to diagnose and treat cancer based on the molecular profi le of each individual patient. Gold nanoparticles have been investigated in diverse areas such as in vitro assays, in vitro and in vivo imaging, cancer therapy, and drug delivery

Multifunctionality is the key advantage of nanoparticles over traditional approaches. Targeting ligands, imaging labels, therapeutic drugs, and many other functional moieties can all be integrated into the nanoparticle conjugate to allow for targeted molecular imaging and molecular therapy of cancer. Gold nanoparticle is unique in a sense because of itsintriguing optical properties which can be exploited for both imaging and therapeutic applications. The future of nanomedicine lies in multifunctional nanoplatforms which combine both therapeutic components and multimodality imaging. The ultimate goal is that nanoparticle-based agents can allow for efficient, specific in vivo delivery of drugs without systemic toxicity, and the dose delivered as well as the therapeutic efficacy can be accurately measured noninvasively over time. Much remains to be done before this can be a clinical reality and many factors need to be optimized simultaneously for the best clinical outcome.

Gold Nanoparticles Cancer Treatment Blog

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Silicon Wafers

SILICON WAFERS

Silicon Wafers is the second most common element on Earth and it is the seventh-most common element in the entire universe. It is the most common semi conductor and the most widely used in the electronic and technology sector. There are different silicon fabrication methods including the horizontal gradient freeze method, the horizontal Bridgeman method, the vertical Bridgeman method, the vertical gradient freeze and finally the Czochralski pulling method.

Silicon Wafers

Silicon Wafers

During the growth process to obtain the derived purity, different intentional dopants are added. These introduced impurities can change the electrical properties of the silicon, which can be useful depending on what the silicon is ultimately being produced for. Boron, aluminum, nitrogen, gallium and indium are just some of the silicon dopants that can be introduced during the growth process. Depending on what level the silicon has been doped, the semiconductor can be considered extrinsic or degenerate. Extrinsic would be lightly to moderately doped whereas degenerate semiconductors act more as conductors because of the high levels of doping that occurs during the fabrication.

Silicon Wafers

Silicon Wafers

Silicon wafers are a key component in integrated circuits. Integrated circuits are, simply put, a composite of various electronic components that are arranged to perform a specific function. Silicon is the principle platform for semiconductor devices. A wafer is a thin slice of this semiconductor material, which serves as the substrate for microelectronic devices built in and over the wafer.

Types of Wafer Substrates

Single Element Semiconductors

Silicon, Si is the most common semiconductor having atomic number 14, energy gap Eg = 1.12 eV, indirect band gap; crystal structure-diamond, lattice constant-0.543 nm, thermal conductivity 1.31 W/cm-oC, melting point 1414 oC due to these properties ingle crystal Si can be processed into wafers up to 300 mm in diameter and having excellent mechanical properties in MEMS applications.

Silicon on Insulator (SOI)

Only a thin layer on the surface of a silicon wafer is used for making electronic components; the rest serves essentially as a mechanical support. The role of SOI is to electronically insulate a fine layer of monocrystalline silicon from the rest of the silicon wafer. Integrated circuits can then be fabricated on the top layer of the SOI wafers using the same processes as would be used on plain silicon wafers. The embedded layer of insulation enables the SOI-based chips to function at significantly higher speeds while reducing electrical losses. The result is an increase in performance and a reduction in power consumption. There are two types of SOI wafers. Thin film SOI wafers have a device layer 1.5 m.

Wafer bonding. – In this process the surface of two wafers are coated with an insulating layer (usually oxide). The insulating layers are then bonded together in a furnace creating one single wafer with a buried oxide layer (BOX) sandwiched between layers of semiconductor. The top of the wafer is then lapped and polished until a desired thickness of semiconductor above the BOX is achieved.

SIMOX – Separation by Implantation of Oxide. In this process a bulk semiconductor wafer is bombarded with oxygen ions, creating a layer of buried oxide. The thickness of intrinsic semiconductor above the box is determined by the ion energy. Anneal reinforces Si-O bonds in the BOX.

Smart Cut – The wafer bonding method is used to form the BOX, but instead of lapping off excess semiconductor (which is wasteful) a layer of hydrogen is implanted to a depth specifying the desired active layer of semiconductor. Anneal at ~500 oC splits the wafer along the stress plane created by the implanted hydrogen. The split wafer may then be reused to form other SIO wafers.

Silicon Wafers

Silicon on Insulator

III-V Semiconductors

Gallium Arsenide (GaAs): After silicon second the most common semiconductor is GaAs having energy gap Eg = 1.43 eV, direct band gap; crystal structure – zinc blend, thermal conductivity 0.46 W/cm-oC, thermally unstable above 600 oC. Due to evaporation they does not form sufficient quality native oxide and mechanically fragile. Due to direct band gap commonly used to fabricate light emitting devices. Because of higher electron and hole mobilities, use for the variety of high-speed electronic devices. The band gap can be readily engineered by forming ternary compounds based on GaAs, e.g. AlGaAs.

Silicon Wafers

Gallium Arsenide

Gallium Nitride (GaN): The wide band gap of III-V semiconductor with direct bandgap 3.5 eV wide; among very few semiconductors capable of generating blue radiation. GaN is used for blue LEDs and lasers; intrinsically n-type semiconductor but can be doped p-type. GaN is formed as an epitaxial layer. The Lattice mismatch remains a problem, creating a high defect density. Incorporation of Indium (InxGa1-xN) allows control of emission from green to violet (high and low In content respectively). GaN can also be used in UV detectors that do not respond to visible light. GaN has a Wurtzite(W) or Zinc Blend(ZB) crystal structure

Silicon Wafers

Gallium Nitride

Gallium Phosphide (GaP): The properties of GaP like Crystal structure zinc blend; Lattice constant [A] 5.45; Density [g/cm3] 4.14; Melting point [oC] 1457, due to these properties of GaP the wafers are used in Semiconductor industry.

Silicon Wafers

Gallium Phosphide

Other Binary Semiconductors

Silicon carbide (SiC): The semiconductor featuring energy gap Eg = 2.9 -3.05 eV (wide band gap semiconductor), indirect band gap; SiC can be obtained in several polytypes- most common hexagonal in the form of either 4H or 6H polytypes; parameters vary depending on polytype; Intrinsically n-doped; p-type doping and n-type conductivity control can be obtained by doping with aluminum and nitrogen respectively. SiC features higher than Si and GaAs electron saturation velocity; excellent semiconductor but difficult and expensive to fabricate single-crystal wafers; excellent for high power, high temperature applications; SiC is closely lattice matched to GaN, has a thermal expansion coefficient close to GaN, and is available in both conductive and semi-insulating substrates. Thus it is often used as a substrate for GaN epitaxial layers. SiC wafers 75 mm in diameter are available commercially.

Fiber Optic

Silicon is the most economical IR material available. Both P-type and N-type substrates are acceptable for IR optics provided that they offer transmission greater than 50% in the 1.5 to 6 micron wavelength. Generally speaking, for N-type, the resistivity should be greater than 20 ohm-cm and, for P-type, greater than 40 ohm-cm. For use in the near IR, this is not so critical, but for applications for the far IR, resistivity can be critical. Float Zone Silicon most always meets criteria for optical use.

Uses of Silicon Wafers

Silicon wafers primary use is in integrated circuits. Integrated circuits power many of the devices that modern society uses every day. Computers and smart phones are just two of the devices that are dependent on this technology. Although other semiconductors have been tested overtime, silicon has proved to be stable option. Other uses include sensors, such as the tire pressure sensor system, and solar cells. Silicon wafers absorb the photons in sunlight and this in turn creates electricity. Silicon wafers are also used for various coating applications of nanomaterials such as biosensing.

Silicon Wafers


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From us, you can easily purchase Silicon Wafers at great prices. Place online order and we will dispatch your order through DHL, FedEx, UPS. You can also request for a quote by mailing us at sales@nanoshel.com Contact: +1 302 268 6163 (US and Europe), Contact: +91-9779550077 (India). We invite you to contact us for further information about our company and our capabilities. At Nanoshel, we could be glad to be of service to you. We look forward to your suggestions and feedback.

Organic and inorganic nanoparticles

Organic and inorganic nanoparticles

Organic and inorganic nanoparticles are materials of two or more dimensions, with a size in the range of 1–100 nm. Nanoparticles show unique size dependent physical and chemical properties, for example, optical, magnetic, catalytic, thermodynamic and electrochemical. The chemical composition and the shape of a nanoparticle also influence its specific properties. Nanoparticles are prepared with organic polymers (organic nanoparticles) and/or inorganic elements (inorganic nanoparticles). Liposomes, dendrimers, carbon nanomaterials and polymeric micelles are examples of organic nanoparticles.

Organic and inorganic nanoparticles

Organic and inorganic nanoparticles

 

Organic and inorganic nanoparticles: Liposomes are phospholipid vesicles (50–100 nm) that have a bilayer membrane structure similar to that of biological membranes and an internal aqueous phase. Liposomes are classified according to size and number of layers into multi-, oligo- or uni-lamellar. Their amphiphilic nature enables liposomes to transport hydrophilic drugs entrapped within their aqueous interior and hydrophobic drugs dissolved into the membrane. Owing to their physicochemical characteristics, liposomes show excellent circulation, penetration and diffusion properties. Moreover, the liposome surface can be modified with ligands and/or polymers to increase drug delivery specificity

Organic and inorganic nanoparticles

Organic and inorganic nanoparticles

Dendrimers are highly branched synthetic polymers (<15 nm) with layered architectures constituted of a central core, an internal region and numerous terminal groups that determine dendrimer characteristics. A dendrimer can be prepared using multiple types of chemistry, the nature of which defines the dendrimer solubility and biological activity. Dendrimers show intrinsic drug properties and are used as tissue-repair scaffolds. Moreover,dendrimers are excellent drug and imaging diagnosis-agent carriers through chemical modification of their multiple terminal groups

 organic and inorganic nanoparticles

Carbon nanotubes Carbon nanotubes belong to the family of fullerenes and are formed of coaxial graphite sheets (<100 nm) rolled up into cylinders. Thesestructures can be obtained either as single- (one graphite sheet) or multi-walled nanotubes (several concentric graphite sheets). They exhibit excellent strength and electrical properties and are efficient heat conductors. Owing to their metallic or semiconductor nature, nanotubes are often used as biosensors. Carbon nanotubes can be rendered water soluble by surface functionalisation. Therefore, they are also used as drug carriers and tissue-repair scaffolds. Inorganic nanoparticles, such as quantum dots, polystyrene, magnetic, ceramic and metallic nanoparticles, have a central core composed of inorganic materials that define their fluorescent, magnetic, electronic and optical properties.

Organic and inorganic nanoparticles

Organic and inorganic nanoparticles

 

Quantum dots Quantum dots are colloidal fluorescent semiconductor nanocrystals (2–10 nm). The central core of quantum dots consists of combinations of elements from groups II–VI of the periodic system (CdSe, CdTe, CdS, PbSe, ZnS and ZnSe) or III–V (GaAs, GaN, InP and InAs), which are ‘overcoated’ with a layer of ZnS. Quantum dots are photostable. They show size- and composition-tuneable emission spectra and high quantum yield. They are resistant to photobleaching and show exceptional resistance to photo and chemical degradation. All these characteristics make quantum dots excellent contrast agents for imaging and labels for bioassays.

organic and inorganic nanoparticles

organic and inorganic nanoparticles

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From us, you can easily purchase nanomaterials at great prices. Place online order and we will dispatch your order through DHL, FedEx, UPS. You can also request for a quote by mailing us at sales@nanoshel.com Contact: +1 302 268 6163 (US and Europe), Contact: +91-9779550077 (India). We invite you to contact us for further information about our company and our capabilities. At Nanoshel, we could be glad to be of service to you. We look forward to your suggestions and feedback.