Comprise advantages and disadvantages of gold Nano particles and quantum dots in the diagnosis of breast cancer by biding to Her-2 and Ki 67 antibodies
Abstract
Today, breast cancer is the most widespread cancer among women and each year, many women will die from this disease. For this reason, the diagnosis of breast cancer in the avoidance of women death is very effective. Many new techniques have been urban to detect breast cancer. One of them is the use of Nano particles. Various types of Nano particles both alone or in combination with other methods, such as CT scan and MRI used to diagnosis of breast cancer. In this paper we compared the advantages and disadvantages of two gold Nano particles and quantum dots. In this study, gold Nano particles with different shapes and sizes and quantum dots with the 566 and 556 wavelength used .They are binding to HER2 and Ki67 antibodies help to detect breast cancer. The diagnosis of cancer is probable by these nano particles which emission fluorescence lights. Also these two types of Nano particles in terms of optical properties, toxicity, cellular uptake and binding to the antibodies are compared together. Despite all the advances in medical nanotechnology there is still a long way from lab to clinical practice.
Key words: breast cancer, Nano particles, gold Nano particles, HER2, Ki67, quantum dots
Introduction
There are various different type of cell in the body, and a lot of different type of malignancy which arise from different type of cell. (1)
One of this is the breast cancer each year more than one million person are diagnose by breast cancer worldwide .more than semi of them will die from this sickness(2 ). Breast cancer is characterized by the uncontrolled expansion of abnormal cells in the milk producing glands of the breast or in the ducts that send milk to the nipple. The majority of breast tumors are carcinomas.(3) There are many way to identify breast cancer counting mammography can be noted that the traditional way.(4) New ways to detect breast cancer have been urbanized which are include using of the Nano particles. There are many profit of using Nano particles These include lower cost, higher precision, resolution at the cellular level, and early detection.(5-6) In this review article, we compare advantages and disadvantages of gold Nano particles and quantum dots, which are used for the detection of breast cancer by binding them to Her_2 and Ki67 anti bodies .
In the past few decades, technology has set immeasurable strides to let visualization, identification, and quantization in biological systems. Several of this technological advancement is occurring on the nanometer range, where multiple scientific disciplines are combining to make novel material by improved property. The integration of inorganic synthetic approaches with a size decrease to the Nano-scale has lead to the formation of a novel category of visual reporters, called qds. (7)
These semiconductor qd Nano crystals have emerged as a different from organic dyes and fluorescent proteins. The broad absorption spectrum, thin emission, photo-stability, not have of photo-bleaching, and high-quantum efficiency have ready these nanostructures very attractive imaging/sensing materials in contrast with the dye flour probes. (7-8-9)
Quantum dots have tunable optical property that have proved practical in a wide range of applications from multiplexed analysis such as DNA detection and cell organization and tracking, to most recently demonstrating promise for in vivo imaging and diagnostics. (10)usually, the fluorescence of QDs depends on the size or shape of the intrinsic Nano particle. QDs can be finely modified via their size and composition to get suitable excitation profiles and high absorption coefficients. (10-9) also, QDs show large Stokes shifts and can endure photo bleaching. For the biological applications of QDs, it is important to manage the surface of core with other semiconductor materials with higher band gap than the core as well as biocompatible polymer. In most of studies, zinc sulfide (ZnS) has been use to cover the core. (10-11)
QDs optical properties can be studied in the assembly or single molecular of physical materials have distinct absorption and emission spectrum for themselves that can be used to recognize for them. They make significant data as stoke shift, inhomogeneous broadening, and thermal spectrum view. (12)
The inhomogeneous broadening arise from variety in QDs size and there is strongly related to electronic organization; optical properties, and particle size. In the absorption spectrum, the decreasing of QD size shifts the onset of it to a visible area due to the growing of band gap energy, moreover by change of the QD size, its emission wavelength and color can be adjusted. (13)
The impact of advances in nanotechnology is particularly related in bio diagnostics, where Nano particle based assays have been urbanized for specific detection of bio analyses of clinical importance.(14, 15) Gold Nano particles show simply tuned physical properties, counting unique optical properties, robustness, and high surface areas, make them ideal candidates for developing biomarker platforms. (16)Modulation of these physicochemical properties can be easily achieved by satisfactory synthetic strategy and give gold Nano particles advantages over conventional detection methods currently used in clinical diagnostics (17)
The surface of gold Nano particles can be modified by ligand fictionalization to selectively attach biomarkers.
Thiol-linking of DNA and chemical fictionalization of gold Nano particles for specific protein/antibody binding are the most ordinary approach. Simple and cheap methods based on these bio-Nano probes. (17,18)
AuNP-based diagnostics can be generally divided in three different Approaches:
1. utilization of the AuNP color variety upon aggregation, the best characterized example being AuNPs functionalized by ssDNA capable of specifically hybridizing to a complementary goal for the detection of specific nucleic acid sequence in biological samples (19);
2. Use of AuNPs as a core/seed that can be modified with a wide variety of surface functionalities to give highly selective Nano probes for diagnosis (20); and
3. Utilization of AuNPs in electrochemical based methods
That can be joined with metal deposition for signal enhancement. (21)Gold Nano particles have been broadly studied for their unique optical properties arising from their surface Plasmon resonance (SPR) (18, 22, 23). Au NPs have extremely high absorption coefficients, allowing higher sensitivity in visual detection methods than usual dyes. (22-24) typically, colloidal solutions of sphere-shaped Au NPs are red with the SPR band centered at ca. 520 nm. This band is feebly dependant on the size of the particle and the refractive index of the immediate media but strongly changes by shape, and inter-particle distance The Morphology and surface chemistry of Nano particles is typically controlled by using suitable synthetic methods (25)
The great enhancement of electromagnetic field at the surface of AuNPs by interaction with electromagnetic waves offers other attractive optical properties with great potential for bio diagnostic assay. For example, AuNPs have been used for single-molecule detection by surface-enhanced Raman spectroscopy (SERS) (26) the successful operation of AuNPs in biological assays relies on the availability of synthetic methods generating Nano particles with the desired characteristics, namely high solubility in water, and adequate morphology, size dispersion, and surface functionalities (27).
Her-2 and Ki 67 antibodies:
Your pathology report might contain information concerning the rate of cell growth — what proportion of the cancer cells within the tumor are growing and dividing to make new tumor cells. A higher percentage suggests a faster-growing, extra aggressive cancer, rather than a slower, “laid back”
one of this examination is measurement of the Ki67.(28) Antigen Ki-67 in addition known as Ki-67 or MKI67 is a protein that in humans is encoded by the MKI67 gene antigen identified by monoclonal antibody Ki-67As a marker for tumor cell proliferation, Ki67 has significant impacts on breast cancer (BC) prognosis Ki-67 is a cancer antigen that is found in growing, dividing cells but is not present in the resting phase of cell growth. This characteristic makes Ki-67 a good cancer marker. This experiment is done on a section of tumor tissue, to help predict your prognosis. (28, 29)
Ki67 is a nuclear antigen firstly identified by Gerdes et al in the early 1980s, by using a mouse monoclonal antibody against a nuclear antigen from a Hodgkin lymphoma-derived cell line. The antigen named following the researcher’s location, Ki67 for Kiel University, Germany, with the 67 label referring to the clone number on the 96-well plate. (30) As a wildly used proliferation marker, Ki67 has attracted increasing notice in current years. a lot of studies showed that Ki67 appearance levels were negatively correlated with BC prognosis (30,31). on the other hand, it is hard to manually measure the Ki67 expression precisely and objectively, significantly limiting its clinical application. The majority common analysis method of Ki-67 antigen is the immune histo chemical evaluation. It was shown that Ki-67 nuclear antigen is expressed in certain phases of the cell sequence namely S, G1, G2, and M phases, but is non existing in G0 (32). In samples from normal breast tissue, it was found that Ki-67 is also expressed at low level (<3 % of cells) in ER-negative cells, but not in ER-positive cells In breast cancer, a result of fewer than 10% is considered low, 10-20% borderline, and high if more than 20%.(31-33)
Receptor tyrosine-protein kinas erbB-2, too known as CD340 (cluster of differentiation 340), proto-oncogene Neu, Erbb2 (rodent), or ERBB2 (human). It is a protein that in humans is encoded by the ERBB2 gene, and it is also often called HER2 (from human epidermal growth factor receptor 2) or HER2/neu. (34) HER2 is a member of the human epidermal growth factor receptor (HER/EGFR/ERBB) family. Amplification or over-expression of this oncogene has been shown to play an significant role in the development and progression of certain aggressive types of breast cancer. In recent time the protein has become an important biomarker and aim of therapy for about 30% of breast cancer patients. (34, 35)
Her-2 a known proto-oncogene, is placed at the long arm of human chromosome 17(36)
The ErbB family consists of four plasma membrane-bound receptor tyrosine kinesis. One of which is erbB-2, and the other members being epidermal growth factor receptor, erbB-3 (neuregulin-binding; lack kinas domain), and erbB-4. (37)All four have an extracellular ligand binding domain, a trans membrane domain, and an intracellular domain that be able to interact by a large amount of signaling molecules and show both ligand-dependent and ligand-independent activity. Particularly, no ligands for HER2 have yet been acknowledged. HER2 can heterodimerise by any of the other three receptors and is considered to be the ideal dimidiation equal of the other ErbB receptors. (38)
Amplification, too known as the over-expression of the her2 gene, occurs in about 15-30% of breast cancers. It is robustly related with increased disease recurrence and a poor prognosis. Over-expression is too known to occur in ovarian, stomach, causes adenoid carcinoma of the lung[ and aggressive forms of uterine cancer, such as uterine serous endometrial carcinoma, e.g. HER-2 is over-expressed in about 7-34% of patients by gastric tumor and in 30% of salivary duct carcinomas. (39)
HER2 is co-localized, and, mainly of the time, co-amplified by the gene GRB7, which is a proto-oncogene associated by breast, testicular germ cell, gastric, and esophageal tumor.(40)
HER2 testing is performed in breast cancer patients to evaluate prognosis and to determine suitability for trastuzumab treatment. It is essential that trastuzumab is limited to HER2-positive individuals as it is expensive and has been linked with cardiac toxicity.(41) For HER2-negative tumors, the risk of trastuzumab clearly outweigh the profit. Tests are typically performed on biopsy samples obtained by either fine-needle aspiration, nucleus needle biopsy, vacuum-assisted breast biopsy, or surgical excision. Immunohistochemistry is used to evaluate the amount of HER2 protein present in the sample. on the other hand, fluorescence in situ hybridization (FISH) can be used to calculate the number of copies of the gene which are present. (42)
Production methods of gold Nano particles and quantum dots
In this study, gold Nano particles of different shapes and different sizes were used to characterize influence the shape and size of gold Nano particle in breast cancer.
The successful use of Au NPs in biological assays relies on the ease of use of synthetic methods generating (43).
Nano particles by the desired characteristics that is high solubility in water, and sufficient morphology, size dispersion, and surface functionalities. Many synthetic methods for the preparation of Au NPs have been reported (44). Most frequently, Au NPs are synthesized with chemical or electrochemical reduction of a gold (III) precursor composite in the presence of a capping agent, i.e. a compound able to attach to the Nano particle surface blocking its development away from the nanometer range and stabilizing the colloid in the particular solvent used. (45) manage of the shape and size of the AuNPs is typically achieved through the careful selection of the experimental conditions namely reducing agent, reaction time, temperature, and capping agent.(46) A ordinary approach is to employ capping agents by strong affinity for gold, e.g. thiol capping agents. Other than in this method switch over of strongly binding capping agents is typically cumbersome, which make This kind of AuNP more limited for biological applications.(47)Due to its simplicity and high yield, the mainly typically used way for preparation of spherical AuNPs for biological assays is the citrate reduction method with Turkevich et al. This manner used citrate as a capping agent is very suitable due to its simple post-synthesis action, since it can be easily replace with other capping agents, e.g. thiol capping agents, bearing an suitable functionality for binding of the biological analytic of interest. Size control is rational, and new modifications have allowed not just for better size distribution of the AuNPs, but too manage of their size within the 9–120 nm range. (48) In principle, quantum dot with appropriate polymer coating can be linked to at all antibodies. But quantum dots used in this study the spectrum of their radiation is in the infrared area to have the lowest Attenuation occurs while crossing.
numerous routes have been used to create QDs but, usually, techniques for QD synthesis used top-down processing methods and bottom-up methods. Top-down processing methods
contain molecular beam epitaxial (MBE), ion implantation, e-beam lithography, and X-ray lithography.(49-50) Using the different bottom-up methods, colloidal QDs are prepared with self-assembling the solution following a chemical reduction.(50) In the methods of top-down, for creation the QDs, a mass semiconductor is thinned. For the reach QDs of diameter about 30 nm, electron beam lithography, reactive-ion etching, and/or wet chemical etching are frequently used. For regular experiments on quantum confinement effect, controlled shapes and sizes are achievable by the preferred packing geometries. on the other hand, focused ion or laser beams have also been used to make arrays of zero-dimension dots. (51)
A number of different self-assembly techniques (bottom-up) have been used to create the QDs, and they might be generally subdivided into wet-chemical and vapor-phase approaches.
: (a) wet-chemical methods mostly follow the conservative precipitation methods by careful manage of parameters for a single solution or combination of solutions. The precipitation procedure always involves both nucleation and limited growth of Nano particles. Nucleation can be categorized as homogeneous, heterogeneous, or secondary nucleation Homogeneous nucleation occurs while solute atoms or molecules mix and make a critical size without the assistance of a pre-existing solid interface. Wet-chemical method are in general micro emulsion, sol–gel, competitive reaction chemistry, hot-solution decay sonic waves or microwaves and electrochemistry (52, 53).
(b) Vapor-phase methods for produce QDs start with processes in which layers are grown in an atom-by-atom process. therefore, self-assembly of QDs occurs on a substrate with no any patterning Self-assembly of nanostructures in material grown with MBE, sputtering, liquid metal ion sources, or aggregation of gaseous monomers are usually categorized below vapor-phase methods MBE has been mostly used to self-assemble QDs from III-V semiconductors and II-VI semiconductors using the large lattice mismatch, e.g., InAs on GaAs has a 7% mismatch and leads to SK growth (54, 55)
Attachment her-2 and ki67 on the surface of QDs for targeting breast cancer cells:
Her-2 and ki67 Antibody was obtained from MCF7 and KPL AND SK-BR-3 cell lines.
Biocompatible QDs have to be cross-linked to bio molecules such antibodies, nucleic acids or small molecule ligands to render them toward precise biological target and consequently be used for diagnosis and targeting drug delivery.(56) For bio conjugation, these molecules can be attached both covalently or non-covalently on the surface of QDs. QDs linked to small molecule ligands, inhibitors peptides or aptamers can attach by high specificity to a lot of Different cellular receptors and targets. (57)Functional ligands of QDs surface such as carboxylic acids, primary amine and thiol can be conjugated by antibodies and peptides by exploiting cross-linking chemistry of carbodiimide maleimide and succinimide. Moreover, eager in biotin cross-linking is one of the most favorite methods for conjugating bio molecules on the surface of QDs (57,58)
Hormone receptors, counting the estrogen receptor and progesterone receptor, human epidermal growth factor receptor 2 (HER2), and other biomarkers like Ki67, epidermal growth factor receptor (EGFR, also known as HER1), the androgen receptor, and p53, are key molecules in breast tumor (59) We be able to attach these hormones to quantum dots to detect and locate tumor in the important steps taken.
In this article we study HER2 and Ki67 connections with quantum dot and gold Nano particle. One method to detect breast cancer as mentioned above is tested and counted Ki67.
But it is hard to manually measure the Ki67 expression precisely and objectively, significantly limiting its experimental applications Automated counting of Ki67 with computer software could be useful, however, And the outcome obtained with automated counting by traditional computer software is the total of Ki67 expression, not the percentage of Ki67 which can be influenced with the number of tumor cells (60). therefore, it is immediate to develop a more precise and objective method to measure the Ki67 expression in BC.
We be able to set up a QDs-based quantitative and in situ multiple imaging on Ki67 so as to better appraise their impacts on BC prognosis.
Imaging of Ki67 was an easier and extra precise method for detecting And assessing Ki67 (61) typically to label ki 67 use from the quantum dot as red signal by QDs-655, The major staining procedures for imaging of ki67 by qds were as following:
BC section heating → Paraffin slide heating → de-paraffin zing →
Hydration → antigen retrieval in citrate buffer → blocking with BSA →primary antibodies for HER2 at 4 °C overnight → staining
With QD-655 simultaneously → washing → image acquisition
And quantification. (62)
Anti-HER2 antibody (ab) (herceptin) is the just suggested biological therapy for treatment of HER2-positive patients; following binding with HER2 receptor, anti-HER2ab checks cell division in breast tumors. (63)QDs have been broadly studied for tumor imaging and diagnosis, and anti-HER2ab-QDs have shown hopeful outcome for HER2 breast cancer detection. Anti-HER2 antibody conjugated by quantum dots (anti-HER2ab-QDs) is a very new fluorescent Nano probe for HER2+ve breast cancer imaging (64). Several types of conjugation methods can be used for the progress of HER2-Qds. The most popular conjugation approaches involve the use of a zero-length cross linker, EDC (1-ethyl-3-(3-dimethyl-aminopropyl) carbodiimide hydrochloride for the configuration of amide bonds between carboxyl groups (presented to the surface of QD) and primary amines of antibodies are covalently bound to the surface of QDs .(65) as well this method, no covalent conjugation of streptavidin covered QDs and bio tinylated antibodies be able to used for prepare HER2Ab-QDs(65,66). on the other hand, the relationship between antibody conjugation approaches and effectiveness of the resulting HER2Ab-QDs for cellular imaging is not obvious
QDs and anti-HER2ab-QDs were characterized with transmission electron microscopy (TEM) and dynamic light scattering (DLS) typically to marker her-2 use from the quantum dot as red signal by QDs-665. (67)
confirmed the successful applications of NIR QDs-conjugated HER2 in fixed and live HER2-overexpressed BC cells. In animal model, QDs-conjugated anti-HER2 antibody was apply to image HER2-overexpressed BC xenografts and see the delivery process of QDs from blood circulation to cancer cell perinuclear area .Animal models studies too found that the fluorescence of QDs straightly conjugated with anti-HER2 antibody was stronger than that of conventional polyethylene glycol (PEG)-coated QDs in visualizing HER2-positive BC xenograft (68).
QD fluorescent information on Ki67 and HER2 of BC was acquired with CRyo Nuance multispectral imaging system below a ultraviolet beam for every QD staining section, a total of 5 spectral cubes contain the complete spectral information at 10-nm wavelength intervals from 450 nm to 700 nm were randomized obtain from different region of the section with CRyo Nuance multispectral imaging systems under the equal exposure time (600 ms). following image acquisition, the software package inside CRyo Nuance multispectral imaging systems was applied to count the QD fluorescence information on Ki67 and HER2 in all cube image. too QDs and anti-HER2aband ki 67 were characterized with transmission a electron microscopy (TEM) , dynamic light scattering (DLS) and focal laser scanning microscopy (CLSM).(67,68)
Attachment her-2 and ki67 on the surface of Au-NPs for targeting breast cancer cells:
Fictionalization of Au-NPs involves the utilize of bio functional ligands in which a moiety is use for anchorage to the particle while the other is directed to the outer-surface for specific interaction with bio molecules.
For example, thiol-modified oligonucleotides have been used to functionalize AuNPs for precise detection of nucleic acid sequence. in biological samples. (69)
Fictionalization of Au-NPs by bimolecular other than nucleic acids has also been used in order
to expand Methodologies appropriate for medical diagnostics. These include:
- Antibodies for signal improvement in immunoassays
- carbohydrate fictionalization to study particular molecular Interactions
And surface fictionalization by ligands that can be modified for specific protein binding or direct binding of peptides and proteins to the Au-Nano particle surface (70, 71)
Binding gold Nano particles to antibodies typically take chemical and physical methods.
Physical interactions:
- Ionic interactions: between positively charged groups in antibodies and the negatively charged surface of the gold Nano particles.
- Hydrophobic interactions: between hydrophobic part of the antibody and the gold Nano particles surface
- Dative binding: between the gold conducting electrons and amino acid sulfur atoms of the antibody
Chemical interactions:
- Chemisorptions via thiol formative
- Bio functional linkers or mediator linkers: EDC/NHS chemistry
- Adapter molecules: like Streptavidin and biotin(72)
- Non-covalent and covalent modes
Binding gold Nano particles and antibodies typically by physical interactions between the positive charge antibodies and negatively charged gold Nano particles take place in current years, Raja Gopal Rayavarapu used this way to attach mouse monoclonal antibody specific to Human EGF Receptor 2 (HER2) to gold Nano particles which were then used as contrast agent for optical imaging techniques of breast.(73)
In a usual process, primary antibodies were initial immobilized on the cancer cells with incubating the SK-BR-3 cells in a buffer containing anti-HER2 antibodies. extra anti-HER2 antibodies were removed by washing the cells by Tris-buffered saline Tween-20 (TBST). Gold Nano particles were conjugated with a secondary antibody (e.g., anti-mouse immunoglobulin G or IgG). In the last level, a buffer solution contains IgG-conjugated Nano particles. (74,75)
typically gold Nano particles with her -2 by a near-infrared (NIR) fluorescent dye is Exposure and were observed with bright-field and dark-field microscopy and were for the first time observed with scanning electron microscopy and energy dispersive X-ray scanning.(76,77)
in attachment of gold Nano particles to ki67 just 20–30% proliferation can be measured in the presence of gold Nano particles. For this reason, the gold Nano particles not employ for imaging of ki67Instead it is used as a marker for cancer treatment .
Compare optical properties of Qd and GNP
Gold Nano particles and quantum dots both are suitable in the treatment and diagnosis of breast cancer.
however every one of them has advantages and disadvantages. First they differ in their size so that Nano particles are usually used for particles in the nm size regime, while quantum dots are those Nano particles that are in \”quantum size regime.
For semiconductor Nano particles, the quantum size regime is gained while their dimensions are lesser than the exaction Bohr radius (for example in CdS such a threshold value is about 5.4nm). For metal Nano particles, is not so simple to describe the conditions for the quantum size regime. (78) Another difference between this the two Nano particles is their optical properties. QDs are about 10–100 time brighter and show narrower and extra symmetric emission spectra than other Nano particles. in addition, QDs present great absorption cross sections, which make them 10-1000times resistant against photo bleaching. QDs have greater optical qualities more than usual fluorescent dyes .because QDs are photo stable while used during long time experiments.(79) Quantum dots are very stable, by excellent quantum yields that be able to achieve up to 90%.The relatively intense luminescence of QDs could be detect at concentration comparable to standard fluorescent organic dyes .(80) The qd also have molar extinction coefficients 10–time those of organic dyes. Qd have the ability to have a wide range of optical properties not present in natural fluorophores such as rhodamine 6G and fluorescent. (81) Organic fluorphores have a thin absorption spectrum which outcome in a thin range of emission. In addition the organic dyes do not have a sharp symmetric emission peak which is more broadened with a red-tail In contrast, qd have a broader excitation spectrum and a narrow more sharply defined emission peak. because of these properties, alone light source be able to used for excite multicolor quantum dots simultaneously without signal overlap. (80-82)
The fluorescence time for qd is about 10 to 40 ns which are longer than the fluorescence of a small number of Nano particles. The inorganic composition of qds also makes them more robust to metabolic degradation which contributes to their long life in vivo. The big Stokes shift (variation between peak absorption and peak emission wavelengths) reduces auto fluorescence which increases sensitivity (82, 83).
In vivo imaging of wide specimens also benefits from the stability and brightness of qds since high absorption, light scattering, and auto fluorescence from endogenous chromospheres can obscure the signal qds have allowed in vivo imaging of tissue of big animals such as sentinel lymph nodes of pigs (1 cm deep). the multicolor property of qds allow the use a lot of probes to track numerous targets in vivo simultaneously.(84)
Optical properties of gold Nano particles are conferred with the interaction of light by electrons on the gold Nano particle surface. At a definite wavelength (frequency) of light, collective oscillation of electrons on the gold Nano particle shell cause a fact called surface Plasmon resonance resulting in strong extinction of light .The particular wavelength, or frequency, of beam where this occurs is strongly dependant on the gold Nano particle size, form, outside and liquid medium. (85) While the optical properties of qd simply depends on its size And therefore their optical properties were more manageable. One more advantage of optical qd is relative to gold Nano particles, Gold Nano particles just in specific wavelengths motivated while the quantum dots can be excited in a wide range of wavelengths.
Gold Nano particles have aggregation property. The aggregation condition of gold Nano particles has an outcome of their optical properties. This fact be able to used to monitor gold Nano particle stability, both over time, and upon addition of salt-containing buffers, which at high enough concentration origin particle aggregation, The red-shift in absorption maximum caused with aggregation, or particles in close proximity, have successfully been used in a lot of assays as a detection method. (86, 87)While qd Nano particles lacking this properties and advantages. Gold Nano particle optical properties too depend on the refractive index near the Nano particle surface. As the refractive index near the Nano particle surface increase, the Nano particle extinction range shifts to longer wavelengths (known as red-shifting). almost, this means that the Nano particle extinction maximum peak location will move to shorter wavelengths (blue-shift) if the particles are transfer from water (n=1.33) to air (n=1.00), or shift to longer wavelengths if the particles are transfer to oil (n=1.5). (88, 89) Dependence of the refractive index of the optical properties of gold Nano particles was similar to a double-edged sword. This can sometimes help imaging and sometimes is a pain in Imaging. But in the qd Nano particles commonly spectral shift due to the refractive index not be created. The optical properties of gold Nano particles depend on its surroundings.the qds are very stable and independent the environment.
Biocompatibility and Solubility
The safe use in biomedicine of semiconductor Nano particles, also famous as quantum dots (QDs), require a comprehensive understanding of the biocompatibility and toxicity of QDs in human beings. Qds since they are usually made of heavy metals are much toxicity for biological environment. For this reason QDs into biological environment often require strategy for the manipulation of the ligands bound to the surface of the quantum dots surface in order to make them water-soluble and biocompatible. (90) Quantum dots have to be rendered water-soluble during the change of their surface in preparation for biological application. Cadmium, which is the most important element in the majority of quantum dots, is known to be very and chronically toxic to cells and organisms. In cells, it is taken into calcium membrane channels, where it accumulates. Its toxicity to living organisms is generally related with liver and kidney damage, osteoporosis and neurological dysfunctions (90-91). Protecting the core can, to some degree, manage toxicity related to cadmium outflow. Since quantum dots photo physical properties are straight associated to surface states, it is critical to manage the surface chemistry of quantum dots while maintaining this for make them biocompatible. In vitro studies have shown that quantum dots toxicity arise from some factors such as chemical composition, size, figure, surface charge, surface covering, and amount. Their ability for photo induced formation of reactive oxygen species (ROS) and Nano particle aggregation are other parameters involved in quantum dots toxicity. (92)
Thus despite this difficulty it is still uncertain this toxic ion can be use as clinical contrast agents.
Fluorescent Nano probes based on gold Nano particles have fine biocompatibility for molecular imaging for a lot of enzymes and metabolites which is essential for cellular functions in cancer. These particles are biocompatible and are readily available for conjugation by little bio molecules such as proteins, enzymes Carboxylic acid, DNA, and amino acids. (93) consequently despite this conditions The employ gold Nano particles to biological environment safer and better. But do not vary in conditions of solubility in water. for qds should use of a polymer covering and for gold Nano particles too Thiolalkylated polyethylene glycol (PEG) ligands have been designed and synthesized for use in the manufacturing of stable water soluble gold Nano particles.(94)
Cellular uptake
This particles are small sufficient to enter cells and we be able to monitor this process using electron microscopy. The microscopy cater the resolution to count numbers of nanoparticles internalized with cells so that we can know the precise dose received by a cell or cell crowd and the final doom of the nanoparticles.(95)
Unlike other engineered nanostructures, QD are simply discovered due to an unusually intense and photo stable fluorescence and are commercially accessible in different sizes and shapes by varied surface coating, creation QD useful tools to characterize the cellular uptake pathways of small particles (96).NP uptake with cells can happen through several different mechanism, and classified into phagocytosis and pinocytosis. We evaluated 24 possible endocytic inhibitors that can be classified into seven main groups based on their effects in cells.
Cytoskeleton, caveolae/lipid rafts, clathrin, macropinocytosis, G-protein joined receptor (GPCR) -related pathway, melanosome transfer mediated pathway, and low density lipoprotein/scavenger receptor associated pathway. The effects of these disincentive on QD uptake were assess by flow cytometry for inhibition definition and too view with co focal laser scanning microscopy (CLSM) for fluorescence imaging.(97)
The physicochemical parameters of QD can affect Nano particle uptake in cells.
The time it takes to distribute qds Nano particles in to Cytoplasm Is about 30 minutes. The fast spread of qds is one of the advantages uses of them. (97)Staining cells with dyes specific to different intracellular organelles showed that QDs were localized in lysosomes (98).Transmission electron microscopy (TEM) images propose a possible pathway for QD cellular uptake method involving three main stages: endocytosis, sequestration in early endosomes, and translocation to later endosomes or lysosomes.(99,100) One of the major advantages is that qds It was observed that the percentage of cells taking up QDs is slightly higher in the cancerous cells than in the non-tumorigenic cells. (101)
TAKelf1 etai find that PEG-derivatization dramatically represses the non-specific uptake as PEG-free carboxyl and amine functional groups promote QD internalization.
These uptake changes represented a remarkable stability across various cell types
Absorbing qd depends on the ambient temperature So that the temperature increment the absorption rate too increases linearly (102).
There is various procedures to conceive and measure gold Nano particle concentration in cells. Because gold Nano particles are electron-dense, it is simple to individualize them from other cellular apparatus with TEM. Other techniques that could be used for imaging Nano particle site are dark field optical microscopy, fluorescence microscopy, and differential interference contrast microcopy. (103)The majority ordinary uptake pathways for Au NPs are different forms of receptor-mediated endocytosis, including clathrin-, caveolin- or raft-dependent uptake. Absorption of gold Nano particles similar to qd absorb depends on the temperature So that the uptake of Nano particles at 4 ° C to 37 ° C Increase 70 percent. The range of Nano particles was found to play a exigent role in together the rate and degree of cellular uptake. It was found that 50 nm transferring-coated GNP were taken up with mammalian cells at better rates and extents compare to smaller and bigger sizes in the range of 10–100 nm. (104)Even if there is ligand-mediated uptake of GNP is considered to be a common methods for their cellular entrance, GNP by “special” surface chemistries/arrangements be able to enter cells with straight permeation that GNPs are able to go in cells and are trapped in vesicles, endosomes and mitochondrion but are not able to enter the nucleus. We did not detect free Nano particles in the cytosol or the nucleus. (105-106) the time required for the distribution of the nano particles in about two hours. Cell activation by exposure to cancer cells necrosis factor or lipopolysaccharide had a slight or no effect on the uptake of Au NPs, respectively. Typically GNPs can accumulate at cancer tissues based on passively targeting mechanism. It has been shown that Au NPs were located in membrane enclosures in the cytoplasm as alone particles or agglomerates of 2–3 more particles. Which can enhance resolution imaging at the single particle level? (107)
A comparison to binding of gold nano particles and quantum dots to her2 and ki 67 antibodies
As in the process and material described above binding GNPs to antibodies frequently takes chemical and physical methods.
Binding GNPs and antibodies typically through physical interactions between the positive charge antibodies and negatively charged GNPs. (40)
GNPs for the reason that of high atomic number has a most ability to attach to antibodies .a 15 nm GNPs contains about 100 000 gold atoms, thus promising to give useful area to attach to antibodies. (108) GNPs have too customizable half-life in blood. The half-life of a few minutes is able to change up to 15 hours. Their blood half-life are longer than iodine agents and promote enhanced tumors uptake.(109) GNPs are typically take place around Tumor and make a shell around them. Penetration into the central part of the tumors was poor, giving slight contrast.(107) In general, for best conjugation, it is suggested that the pH of the antibody and gold slob maintained at or a little higher than the iso electric point (pI) of the antibody. After binding GNPs to antibodies, the characteristic red-shift in the extinction peak of the Plasmon bands is seen. (110)
Frequently GNPs cannot enter the cell nucleus and are in the cytoplasm. And since Ki67 is a element of cell nucleus connecting them to GNPs Not very useful. For this reason it does not much use in these methods. And this is a disadvantage for gold Nano particles in diagnosis of breast cancer because the impact of Ki67 in the early finding of breast cancer is much more of HER2.
Anti-HER2 antibody conjugated with QDs (anti-HER2ab-QDs) is a very new fluorescent Nano probe for HER2+ve breast cancer imaging. Some kinds of conjugation approaches can be used for the progress of HER2-Qds. The mainly popular conjugation approaches involves the use of a zero-length cross linker, EDC (1-ethyl-3-(3-dimethyl-aminopropyl) carbodiimide hydrochloride for the configuration of amide bonds between carboxyl groups (introduce to the surface of QD) and primary amines of antibody antibodies are covalently bound to the surface of QDs. moreover this method, no covalent conjugation also used for antibody conjugated by QDs (64-65). The fluorescence imaging of HER2 appearance can be performed with using a very low concentration (10 nM) of HER2-QDs. This is a significant advantage in opposition to gold Nano particles since the concentration of gold Nano particles will further develop image quality, and this requires a high dose of gold Nano particles will be. Compared by usual IHC GNP and FISH, the QD-based HER2 detection process is simple, quick and economic. (111)
Preparation of anti-Ki-67 antibody conjugated was carried out with adopting a straight conjugation of antibody to the carboxyl group functionalized by EDC-NHS chemistry. As these methods are completely described in the above. In this way the surface carboxyl groups on qd provided with citrate capping made this conjugation easy. (112)
Conclusions:
In the last few years use of Nano particle in clinical diagnosis has developed quickly and for every particular application of them most use of certain type of Nano particles.
Consequently, we should decide the desired Nano particles with consideration their application in different fields. In this article we were compared gold Nano particles with quantum dots in several fields In terms of optics, toxicity, cellular uptake and binding to antibodies. The quantum dot optical properties are much better than gold Nano particles. Because the quantum are brighter than other Nano particles and show
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