Monday, 24 October 2016

A Seminar Report On Nanotechnology As A Diagnostic Tool | A Project On Nanotechnology As A Diagnostic Tool

NANOTECHNOLOGY AS A DIAGNOSTIC TOOL

BY


OYIKWU VICTORIA ENE
(MLS/11/161)



A SEMINAR WORK PRESENTED IN
PARTIAL FULFILMENT OF the REQUIREMENTS FOR THE
AWARD OF BACHELOR OF DEGREE IN
MEDICAL LABORATORY SCIENCE (B.MLS)


IN

DEPARTMENT OF HAEMATOLOGY/BLOOD TRANSFUSION SCIENCE
(MEDICAL LABORATORY SCIENCES)

MADONNA UNIVERSITY, ELELE CAMPUS
RIVERS STATE, NIGERIA

course CODE: mls 522

COURSE TITLE:  SEMINAR

SUPERVISOR:  MR. AJUGWO ANSLEM

cordinator: dr.  ADEBAYO .O. ADEGOKE


march, 2015



CERTIFICATION

This is to certify that this seminar work titled “Nanotechnology as a diagnostic tool” was done by Oyikwu Victoria Ene with the registration number MLS/11/161 in the Department of Haematology/blood transfusion science, Faculty of Medical Laboratory Science, Madonna University Elele Campus, River state.
Under the supervision of Mr.  AJUGWO ANSLEM.


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Oyikwu Victoria Ene                                                                     Date
         (Student)


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 Mr. Ajugwo Anslem                                                                         Date
          Supervisor   


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Dr. Adebayo. O. Adegoke                                                                Date
      Coordinator



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Asso. Prof.  Nnatuanya Isaac .N.                                                      Date
          H.O.D







DEDICATION
This piece of work is dedicated to the most sacred of Jesus Christ and immaculate heart of Mary.

ACKNOWLEDGEMENTS
All thanks and praises be to God for his unending love, mercy, blessings and grace. I am where I am because He is who He is.

To my beloved parents I want to say thanks for your love and words of encouragement may the good lord reward you according to his riches and glory. You are the best parents anyone could ever have, and I love you.
I am grateful to my supervisor Ajugwo Anslem for his thorough and constructive criticism which provided me with challenges to meet the needs of this essay.
I would also like to acknowledge the seminar coordinator Dr. Adebayo Adegoke, am grateful to you Sir. And may God reward the rest of my lecturers in my department that contributed in one way or the other in impacting knowledge and discipline into me….Amen!
And to my siblings I want to say I love you all and I appreciate all your support, may your joy know no bounds.
My course mates and friends Ada, Lauretta, Isioma, Ambrose, Simony, Mercy and Dorcas may you all experience joy, peace and Gods unending favour in everything you do. Amen


SUMMARY
 Nanotechnology is the manipulation of material on an atomic and molecular scale; by changing its physical, chemical and biological properties to produce novel materials, devices, and systems. Nanomaterials exhibit remarkable characteristics such as high surface to volume ratio, catalytic activity, and biocompatibility which make them suitable for various biomedical applications. Nanotechnology have prospective to improve the whole healthcare process for patient; starts from diagnosis to treatment and follow-up monitoring. Medical diagnosis based on nanotechnology provides two major advantages: rapid testing and early diagnosis. The potential contributions of nanotechnology in the medical diagnosis are extremely broad and improve traditional diagnostic tools and methods in the field of clinical diagnosis, imaging and electro- diagnosis. Emerging modalities such as biochip, microarray, Nano barcode, micro-electromechanical systems, lab on chip and nanobiosensor have revolutionized the field of medical diagnosis. Nanoscale materials and Nano-enabled techniques are used for diagnosis of various diseases such as cardiovascular diseases, cancer, diabetes, infectious disease, musculoskeletal and neurodegenerative disease etc. Among all medical applications of nanotechnology, nanobiosensor especially enzyme nanobiosensor are sensitive, reliable, robust, reproducible and cost effective diagnostic tool to meet the requirements of healthcare.                                          Nanotechnology also have disadvantages like making atomic weapons more accessible, more powerful and more destructive. Because nanotechnology makes use of small particles, It also give problems like inhalation of those minute particles much like the problems a person gets from inhaling minute asbestors particles.






TABLE OF CONTENTS
Title page………………………………………………………………….……i
Certification………………………………………………………………….…ii
Dedication……………………………………………………………………...iii
Acknowledgement………………………………………………………...........iv
Summary………………………………………………………………………. v
Table of Contents………………………………………………………………vi

CHAPTER ONE
1.0  Introduction………………………………………………………………..1

CHAPTER TWO
LITERATURE REVIEW
2.0     what is nanotechnology……………………………………………………3
2.1      Nanomaterials in medical diagnosis…........................................................3
2.2      Applications of nanotechnology in medical diagnosis..………….……….7
2.3      Emerging trends in nanotechnology…………………………….……….10
2.4      advantages and disadvantages of nanotechnology………………………22

CHAPTER THREE   
3.0  Conclusion/Recommendation………………………....................................23
              References………………………………………………………………….........24




                                                           CHAPTER ONE
1.0                                                   INTRODUCTION
According to the American heritage dictionary of the English language, 4th edition, Nanotechnology can be seen as the development of engineered devices at the atomic, molecular and macromolecular level in nanometer range. It can also be seen as the science and technology of small things in particular, things that are less than 100nm in size. Nanotechnological devices are being developed for diagnosis of cancer and infectious diseases which can help in early detection of the diseases. It also have been beneficial in therapeutic field such as drug discovery, drug delivery and gene/protein delivery. It can also be seen as the creation of very small particles, devices and systems: these technology takes place at a very minute level (Silva, 2004).
       Nanotechnology as a diagnostic tool refers to the use of Nano materials for the early detection, prevention treatment and follow up of many life threatening diseases including cancer, cardiovascular diseases, diabetes, Alzheimiers and AIDS as well as infectious disease (Tallury, 2010).
      The auspicious application of nanotechnology is in Alzheimer’s disease because patients are diagnosed after they pass away and their brain is examined for telltate damage, scientists are investigating for test that will make up diagnosis in living patients (Shinjini et al., 2008). The use of nanotechnology enables the development of novel therapies and improves traditional treatment and diagnosis process by manipulating atom and molecules to produce nanostructures of same size as biomolecules for interactions with human cells (Fakruddin et al., 2012).
Hexagonal shape and are few hundred nanometers tall and apart. These Nano structures are used to enhance the absorption of infra-red light (heat) in in a type of power source called thermo-voltaic cell to make them more efficient.       Nanotechnology makes use of Nano structures which includes the use of moth’s eye which has a very small bumps on its surface, they have Nanotechnology can be applied in areas like medicine and health care, environment, energy, information and communication technologies.

Different nanomaterials are used for diagnostic purposes these include
·        Magnetic nanoparticles
·        Quantum dots  
·        Carbon nanotubes.
·        Graphene oxide.
·        Gold nanoparticles and silver nanoparticles.
·        Porous nanomaterial.

The aim of clinical diagnosis is the rapid testing and complete diagnosis at an earlier stage to prove the potential of curing, possibly with less damage to the patient. It is possible with points of care diagnosis. Which includes nanobiosensor and nanoscale devices. Bringing the diagnostic technique with patient point care which reduces disadvantages of conventional diagnosis and overall cost and time for health care process for patient is reduced extensively (Richard et al., 2009).
      Numerous techniques and assays are available for diagnosis such as immunoassay, genetic based tests, medical imaging and bio sensing. Bioassays commonly used in diagnosis are enzyme linked immunosorbent assay (ELISA), polymerase chain reaction (PCR) based genetic assay and such as giemsa and Gram for viral and bacterial infections diseases (Challa, 2007).
  Conventional diagnostic methods suffer from few limitations occurring as a result of low specificity and lack of efficacy. So nanotechnology enhances assays by accomplishing all requirements to provide a platform that is more sensitive than the current gold stand in protein detection and ELISA (Gaster et al., 2011).






CHAPTER TWO
LITERATURE REVIEW
2.0                                       WHAT IS NANOTECHNOLOGY
         Nanotechnology is the manipulation of matter at the atomic and molecular scale to create materials with new and advanced properties. It is applied in diagnosis through the development of nanoparticles/materials to detect early stage of a disease and also to ensure rapid diagnosis and treatment of diseases.
       Nanotechnology as a diagnostic tool refers to the use of Nano materials for the early detection, prevention treatment and follow up of many life threatening diseases including cancer, cardiovascular diseases, diabetes, Alzheimiers and AIDS as well as infectious disease (Tallury, 2010).

2.1           NANOMATERIALS FOR MEDICAL DIAGNOSIS
            Nanomaterials exhibit higher chemical reactivity, increased mechanical strength, faster electrical and magnetic responses owing to its high surface to unit volume ratio. Nanoparticles can attach to biomolecules allowing detection of disease biomarkers in a laboratory sample at a very early stage. These materials are designed to interact with cells and tissues at a molecular (i.e. subcellular) level with high degree of functional specificity, thereby allowing integration between the device and biology system not previously attainable (Silva, 2004).
    Nanomaterials possess electrical conductivity catalytic properties, good stability and high loading biomolecules owing to its high surface to volume ratio. Because of their small size, nanomaterials can readily interact with biomolecules and gaining access to so many areas of the human body. Nanomaterials are produced using the top down and bottom up techniques. The top down start with a bulk material and then breaks it into smaller pieces using mechanical, chemical or other form of energy. An additional way is to synthesize the material from atomic or molecular species through chemical reactions allowing for the precursor particles to grow in size which is called bottom up technique. Chapter 6 nanomaterials, springer.
      Nanomaterials become a platform fabrication of novel diagnostic tool and revolutionized diagnostic processes by increasing relative surface area and emergence of quantum effects and interactions with biological systems present opportunities for scientists. The effect of increased reactivity and the potential to cross cell membranes have positive impacts on healthcare (Shao et al., 2010).
Nanomaterials include; Magnetic nanoparticles, quantum dots, carbon nanotubes, graphene oxide, gold nanoparticles and silver nanoparticle, porous nanomaterial.


v MAGNETIC NANOPARTICLES
Magnetic nanoparticles are employed in multiple disciplines such as biosensors, magnetic resonance imaging and Nano electronics. It commonly consist of magnetic element such as iron, nickel and their derivatives. They are versatile diagnostic tool as they are manipulated using external magnetic field. Its action at a distant phenomenon, combined with intrinsic penetrability of magnetic field into human tissue enables their detection in vivo using magnetic resonance imaging (MRI) (Shao et al., 2010).
      Magnetic nanoparticles for biosensors enhance sensitivity and effectively reduce sample preparation requirements. Magnetic sensors such as magnetic relaxation switch assay sensors, magneto resistive sensors and magnetic particle relaxation sensors have been developed (Koh and Josephson, 2009).
    Supra- paramagnetic iron oxide nanoparticles (SPION) are made of iron oxide core and coated by either inorganic materials like silica or organic materials such as phospholipids and natural polymers such as dextran or chitosan are versatile agent for early diagnosis of cancer, atherosclerosis and other diseases. They are used as contrast agents for magnetic resonance imaging and as an in-vitro application in bioassay by means of a vehicle for the detection of biomarker (Hofmann et al., 2010). When supra- paramagnetic iron oxide are used in biosensors it improves the sensitivity and selectivity of diagnosis (Azzazi et al., 2007).


v     QUANTUM DOTS (QD)
They are spherical fluorescent nanocrystals made of semi conductor materials of intermediate sizes typically between 2-8nm in diameter.  They are widely used as alternative to conventional fluorophores and for development of biosensors to detect biomolecules such as proteins, neurotransmitters enzymes and amine acids (Azzazi et al., 2007).
Bio conjugated quantum dots have the potential to b used in cancer diagnosis due to its bright and stable fluorescent light emission and sensitivity of fluorescence imaging (Smith et al., 2006). They can also be used in the future for locating cancer tumors in patients and in the near term for performing diagnostic tests in biological samples (Xing and Rao, 2008).


v CARBON NANOTUBES (CNT):
These are extensively used nanomaterials in biosensors and diagnosis. They are long hollow cylindrical carbon structures composed of one, two or several concentric graphite layers capped with fullerenes hemisphere which are referred to as single, double and multi- walled . I.e. they have unique mechanical, optical and electronic properties with high electrical and thermal conductivity.
Carbon nanotubes have aspect ratio, unique optical property and small sizes exhibit potentials for variety of biomedical applications including the diagnosis of cancer and infectious diseases. These applications are encouraged by their capability to penetrate biological membranes and relatively low toxicity (Zhang et al., 2010).
      For diagnosis carbon nanotubes can help to detect a protein biomarkers of disease when fabricated on the surface of a Nano biosensor. When it binds with a protein, the nanotubes change their electrical resistance which then be measured to determine the presence of a particular protein. E.g. serum protein biomarkers that can indicate breast cancer (Leyden et al., 2012). Carbon nanotubes also have potential to increase the speed of biological sensors by reducing the biosensor response time. (Vashist et al., 2011).


v  GRAPHENE OXIDE (GO):
Graphene oxide is a thin layer of sp2 hybridized carbon extensively used for medical diagnosis due to its exciting properties, turn able band gap, high elasticity, high mechanical strength, very high temperature quantum hall effect, high electron mobility and high thermal conductivity (Dresselhaus and Araujo, 2010).
   Graphene oxide can also be seen as transparent material with low productivity cost and minimum environmental impact. The sheets of graphene oxide on which antibodies attaches binds to cancer cells which then tag the cancer cells with fluorescent Molecules to make the cancer cells to make the cancer cells stand out in a microscope. It can also detect a very low level of cancer cells as low as 3 to 5 cancer cells in a one milliliter of blood sample (Rajashekhar et al., 2014).


v GOLD NANOPARTICLES (AUNPS) AND SILVER NANOPARTICLES (AGNPS):
Nano sized gold nanoparticles and silver nanoparticles are precious and in great demand by scientists. Gold nanoparticles are most attractive and extensively studied nanomaterials in bioanalytical field for medical diagnosis owing to its fascinating features such as ease of synthesis, high biocompatibility and Nano cytotoxicity. They have biomedical applications in these areas; labeling and bio sensing. For labeling, certain properties of the particles are exploited to generate contrast.
Gold nanoparticles can also be used in biosensors as their optical properties can change upon binding to certain molecules permitting the recognition and quantification of annalites. The silver Nano rods in a diagnostic system are being used to separate viruses, bacteria and other microscopic components of blood samples. This method has been demonstrated to allow identification of viruses and bacteria in less than an hour (Shanmukh et al., 2008).


v PORUS NANOMATERIALS:
The porous nanomaterials are particularly promising for fabrication of optical biosensors as it possesses wide range of physical characteristics such as high purity, turn able porosity, Nanoscale structuring, high photochemical, physical rigidity and thermal stability. Porous nanomaterials retain native conformations and reactivity of biomolecules (Satvekar et al., 2012).


2.2                        NANOBASED DIAGNOSTIC TOOLS

1. NANOBARCODES
          Nano barcodes acts as   encoded substrates in multiplexed assays which are metallic, durable, encode-able and machine readable submicrosized tags (Griffith et al., 2008). They are free standing, cylindrical nanoparticles with specific patterns of sub micro stripes of noble metal ions produced by alternating electrochemical reduction of the appropriate metals (Zhou et al., 2001).
         Nano barcode is advantageous in coding multiplexed assays for proteomics, single nucleotide polymorphism (SNP) mapping and in point of care handheld devices.
        Nano barcode assays are nanotechnological based technique for detecting proteins which extraordinary sensitivity in detecting certain antigens at extremely low concentrations which is now devoid of the use of polymerase chain reaction (PCR). These assay uses disease biomarkers that cannot be used in the conventional assays. ADDLs are considered neurotoxins in Alzheimer’s disease (AD) pathogenesis clinically detected by a new diagnostic approach for AD using the Nano barcode assay (David et al., 2003).


2.  NANOBIOSENSORS
        Biosensors are widely in medical diagnosis to scrutinize or detect biomarkers for diagnosis of various diseases starting from diabetes to cancer. Due to the recent progress in biosensor fabrication, diagnosis of life threatening diseases more reliably.
         Nanotechnology provides great opportunities to improve the sensitivity, stability and anti-interference ability of biosensor system. And with the progress in nanotechnology various novel nanomaterials have been invented and their novel properties are being gradually revealed which greatly enhances the performance of biosensor. Due to small sized nanoparticles the limitations of minimization leading to lower detection limits even getting zepto-molar concentrations are overcome. Nanoparticles can produce a synergic effect between conductivity, catalytic activity, and biocompatibility to enhance the signal transduction. Also nanoscale materials are used in biological sensors in detection of biomolecules. These nanomaterials based nanobiosensing involves in vivo diagnosis with high sensitivity, less cytotoxicity and long term stability for early screening of biomarkers and reliable point of care diagnosis (Huangxianju et al., 2013).
       Nano biosensors have made a great impact due to their capacity to sense a wide range of biomolecules and incredibly small concentrations (Turner, 2013).


              NANOBIOSENSORS FOR CLINICAL DIAGNOSIS
IUPAC defines biosensor as a sufficient integrated device which is capable of providing specific quantitative or semi-quantitative analytical information using a biological recognition (biomolecules through enzyme, DNA and antibody) which is retained in direct spatial contact with a transducer element. These biomolecules include antibodies, enzymes nucleic acids, cell and bio mimic component employed as bio recognition element which is highly favourable owing to its specificity and catalytic activity (Thevenot et al., 2001).


             PRINCIPLE OF BIOSENSOR
Biosensor comprises of a bio recognition element in intimate contact with a proper transducer. These bio recognition element gives rise to signal as the biochemical reaction of interested analyte which is detected by transducer to give electrical signal. This reaction between the biomolecule and the substrates produces a product in the form of electrochemical heat light or sound and then a transducer in form of electrochemical semi-conductor or thermistor which changes the product of the reaction into readable data.

         
BIOSENSOR COMPONENT
A biosensor consist of three components which are;
1. The biorecognition element e.g. enzymes, antibodies, nucleic acids, cell lysates, micro organisms, cell receptors etc.
2. The transducer which acts as an interface, measuring the physical change that occurs with the reaction at the biorecognition element and then converting that energy into measuring electrical output. These transducer can be optional, electrochemical, opto-electronic, piezoelectric, thermal and mass.
3. The detector element which passed signals from the transducer to a microprocessor where they are amplified and analyzed (Clark and LYONS, 1962).


TYPES OF NANOBIOSENSOR BASED ON TRANSDUCER MODE
Biosensors  can  be  generally  classified  into  two  criteria’s  based  on  sensing  element  and  transduction modes.  Transduction mode depends on the physiochemical change resulting from sensing element.  Hence  on  the basis  of  different  transducers,  biosensors  can  be electrochemical  (aerometric,  conductometric  and potentiometric),  optical  (absorbance,  fluorescence  and chemiluminense), piezoelectric (acoustic and ultrasonic) and  calorimetric (Habermuller et al.,2000).  The major types based on transducer mode are discussed below:


ELECTROCHEMICAL BIOSENSOR
 AMPHOTERIC NANOBIOSENSOR: Amperometric biosensor is based on the electrochemical analysis in which the signal of concern is a current that is linearly dependent upon the concentration of the biomarker. The signal transduction process is accomplished at a fixed potential between the working electrode and a reference electrode, and measuring the current as a function of time which is a direct measure of the rate of electron transfer. In most cases the biorecognition element is immobilized on the working electrode. The analyte is oxidized or reduced at the working electrode and the current flow directly proportional to the concentration of the electro-active species (Baker, 2004)

POTENTIOMETRIC NANOBIOSENSOR: In potentiometric sensors, the potential difference between the reference electrode and the indicator electrode is measured without polarizing the electrochemical cell. The analytical information is achieved by transforming the biorecognition process into a potential signal. A permselective ion-conductive membrane and high impedance voltmeter is normally utilized to measure the potential signal, which arises when the analyte interacts with the surface. The electrical potential difference or electromotive force (EMF) measured between two electrodes at near zero current. The indicator electrode or an ion-selective electrode (ISE) develops a change in potential as a function of analyte concentration in sample (zarina et al., 2003).

CONDUCTOMETRIC NANOBIOSENSORS: These are based on the measurement of electrolyte conductivity, which varies when the cell is exposed to different environments. Conductivity measurements are generally accomplished with AC supply which is a linear function of the ion concentration. Conductometric-based biosensors couple conductance and a biorecognition event in which mostly reactions involve a change in the ionic species concentration and this can lead to a change in the solution electrical conductivity. The major problem with this technique is that the sensitivity is generally lower compared to other electrochemical methods (Dey and Goswami, 2011).

 OPTICAL BIOSENSORS: Optical biosensors (optodes), have received considerable attention for diagnosis. The optical biosensors involve direct detection of the analyte of interest or indirect detection through optically labeled probes. In general, there are at least four types of biosensors using the principles of optical technology. These are as follows: absorption, reflection, chemiluminescence, fluorescence, and phosphorescence.
           Optical biosensors are potent alternative to conventional analytical techniques because these are highly sensitive, reproducible, rapid, and simple-to-operate. The optical biosensor design encompass direct detection of the interested analyte  or indirect detection through optically labeled probes, and the optical transducer may detect changes in the absorbance, luminescence polarization, and refractive index (Kim et al., 2004).

PIEZOELECTRIC NANOBIOSENSORS: These biosensors are mass sensitive detectors, which has the principle that an oscillating crystal resonates at the natural resonance frequency. The piezoelectric materials are able to generate and transmit acoustic waves. When a piezoelectric biosensor surface is coated with a biomolecule (antibody) and placed in a solution containing the pathogen, the attachment of it to the antibody coated surface results in an increase in the crystal mass, and this shows a corresponding frequency shift. This mechanism is relatively simple, inexpensive, and offers direct label-free analysis (Cooper, 2003).

 CALORIMETRIC NANOBIOSENSOR: Most chemical and biochemical processes involve the generation of exothermic heat which is used as a basis for measurement of rate of reaction and ultimately analyte concentration. The fabrication of the Calorimetric biosensor normally consist a thermistor or thermopile employed as a temperature transducer to determine heat changes (CLARK and LYONS, 1962). The device is covered with the enzyme and when this interacts with the analyte it generates an exothermic reaction, which is recognized as a heat change. Obvious benefits of this biosensor are that it can be easily miniaturized, can be used in turbid samples, and it is a label-free approach (Xie et al.,1999).

TYPES OF NANOBIOSENSOR BASED ON BIORECOGNITION ELEMENT
 Sensing elements include enzymes, antibodies (Immunosensor), micro-organisms (whole cell biosensors), and DNA. The main types based on are as follows:

DNA Nanobiosensor: The DNA nanobiosensor is based on the conversion of the base-pair recognition event or hybridization event (the complementarities of adenine-thymine and cytosine-guanosine pairing in DNA) into a measurable electrical signal. DNA duplex formation or hybridization event forms the basis of electrochemical detection in which electrochemical signals are generated and enhanced by covalent binding of nanomaterials to the DNA probe. DNA probe is the known sequence of bases which can be synthesized and labeled with optically detectable compounds. DNA biosensors are utilized as suitable candidate for rapid and reliable diagnosis of genetic diseases, the detection of pathogenic biological species (Wang, 2002).

IMMUNO-NANOBIOSENSOR: these are Biosensors which monitor antigen- antibody interactions. Immunosensor monitor antigen-antibody interaction in which either antigen or antibody is immobilized on a solid-state surface of electrode and participate in bio specific interaction with the other component, allowing detection of desired biomolecule. Antigen-antibody reactions  are  very  specific  and  a  very  minute concentration  of target  molecule in the body  can be detected and easily screened (Stefan et al., 2000). Immunoreactions are known for their high sensitivity and selectivity so most reliable tool for clinical diagnosis. Optical and electrochemical detection strategies are mostly used in immunosensor.  

ENZYME NANOBIOSENSOR: Enzyme nanobiosensor plays a vital role in diagnosis of various diseases which are composed of enzyme as biorecognition component that uses their catalytic activity for detection of analyte. The success of any enzyme sensor depends on enzyme loading, the use suitable pH and type of immobilization method and how well it retains its enzymatic activity on transducer. The most important part of a biosensor fabrication is the immobilization of a desired enzyme (Sassolas et al., 2012). However, the usefulness of immobilized enzyme on electrodes depends on factors such as the immobilization method, the chemical and physical conditions (pH, temperature and contaminants), thickness and stability of the membrane used to couple the enzyme.

WHOLE CELL NANOBIOSENSOR: Whole cell biosensors utilizes living cells or Microorganisms such as bacteria and fungi as the biorecognition element which can detect the intracellular and extracellular conditions, physiological biomolecules to produce a response. The detection limit of these biosensors is mainly measured by the environmental conditions in which the cells can remain alive for long period. However the major drawback of whole cell biosensor is the stability of the whole cell, which depends on several conditions such as the lifetime, sterilization, and biocompatibility etc. Despite these consequences the whole cell biosensor is still promising among the researcher due to the advantages it has over the other biosensors. (Belkin and GU 2010).


                                            ENZYME NANOBIOSENSOR
          Enzymes are used reliably in the medical field such as in the diagnosis and treatment of various diseases. For example, enzymes are used in biosensors for the detection of various biomarkers such as glucose, cholesterol, uric acid. Enzymes are most favorable candidate as a biorecognition element in the fabrication of biosensor because of its selectivity compared to conventional catalyst. However, enzymes are prone to the microenvironment (PH, temperature) and have a short operational lifetime. In aqueous solutions, enzymes lose their catalytic activity rapidly due to the oxidation reaction or their tertiary structure can be destroyed in air-water interface, these shortcomings can be avoided by immobilization of enzymes. Immobilized enzymes are more robust and advantageous such as convenient handling, more resistant to environmental changes and increase the affinity for the substrate (Rajshri et al., 2014).
             The detection limit of enzymatic biosensors is generally determined by the enzyme’s activity. However, the major drawback with enzymatic biosensors is the stability of the enzyme, which be influenced by conditions such as temperature, pH and buffer etc. The capability to conserve enzyme activity for a long period of time up till now remains a major obstacle. Regardless of these pitfalls, the enzymatic biosensor is still the most usually used biosensor, and this is essentially due to the prerequisite for monitoring glucose, cholesterol, uric acid, lactate for diagnosis of various diseases in blood.

 ENZYME NANOBIOSENSOR FOR CLINICAL DIAGNOSIS

 GLUCOSE: The abnormal level of glucose related to diabetes and the risk for renal, retinal, and neural complications. Thus the measurement of glucose in human blood is important for diagnosis of diabetes and other diseases. Glucose biosensors based on glucose oxidase have been dynamically investigated as the potential biosensor with wide range of analytical techniques (Scognamiglio, 2013).

 CHOLESTEROL: The increasing prevalence of cardiac arrest and cardiovascular diseases are major reason of death in human worldwide. The cholesterol level detection in human blood is of great significance in clinical diagnosis as high cholesterol in blood is associated with coronary heart disease, hypertension, myocardial infarction, brain thrombosis, arteriosclerosis, lipid metabolism dysfunction, etc. (Arya et al,2008). In conventional assays, cholesterol determination is performed by enzymes, such as cholesterol oxidase and cholesterol esterase which can be used to monitor both free and esterified cholesterol levels.

 URIC ACID:  A major nitrogenous compound of urine is uric acid which is the product of purine metabolism in the human body. It is correlated to many clinical disorders; high levels of uric acid in the blood are associated with gout, hyperuricemia, Lesch-Nyhan syndrome and other conditions including increased alcohol consumption, obesity, high cholesterol, diabetes, high blood pressure, kidney disease and heart disease. Lactate: The level of lactic acid in blood is used in clinical diagnosis of hypoxia, lactic acidosis, some acute heart diseases.

LACTATE: The level of lactic acid in blood is used in clinical diagnosis of hypoxia, lactic acidosis and some acute heart diseases. Trustworthy, blood lactate detection method would also be of interest in sports medicine.

  UREA: Urea is generally monitored in blood sample to obtain evidence of kidney disease. It is the best biomarker for evaluating the level of uremic toxins in body. Eggshell membrane is a natural materials used as a membrane for immobilization of urease enzyme for the development of a potentiometric urea biosensor and showed good operational and storage stability (Dsouza et al., 2013).

FARBRICATION OF ENZYME NANOBIOSENSOR
 The basic requirements for an enzymatic nanobiosensor are:

  (1) an enzyme which acts on its substrate to produce a molecule which is capable of being reduced or oxidized at an electrode surface;

 (ii) an immobilization technique for the enzyme to ensure close proximity of enzyme to the electrode which retains the functionality of the enzyme; 

(iii) an electronic system proficient in controlling the potential of the electrode and measuring the current produced in the redox reaction. For the immobilization of enzyme chemical and physical methods such as covalent binding, absorption, cross-linking, entrapment, and encapsulation have been used. These techniques suffer from some disadvantages like leaching of biomolecules and loss of activity. Accordingly, choice of the immobilization materials and methods should be carefully considered to maintain the enzyme activity for a long time under various conditions. The fabrication of biosensor is dependent on factors like prerequisite of analysis, techniques employed and cell configuration. Conventionally, bulky electrodes and “beaker-type” cells configuration have been utilized. But nowadays, micro-fabrication permits the replacement of these traditional cells configuration and bulky electrodes with appropriate sensing devices. The innovative techniques such as thick and thin film technology, Screen-printing technology and photolithography are used in fabrication of biosensors for clinical diagnosis (Gonzalez-Macia et al., 2010).

          The fabrication technique which is well suited for mass production and portable devices allow both in situ and real time monitoring. Perhaps, disposable screen-printed strips are commonly used by diabetic patients for self-monitoring of blood glucose levels. Such fabrication method offers mass production of really inexpensive and hitherto highly reproducible enzyme biosensor.

2. MICROARRAYS
         Microarrays are promising for competent and personalized approaches to human health care. Microarray offer a powerful tool for screening thousands of proteins at a time, where variety of biomolecules such as antibodies and enzymes are immobilized in an array format on glass slide (Zhu and Synder, 2003).
         The surface of the glass slide is then probed with sample of interest that binds to relevant antibodies on chip which will be analyzed by detection method on microarray. Profiling proteins on arrays will be used in distinguishing the proteins of normal cells from early stage cancer cells and malignant metastatic cancer cells. Likewise, it also helps to sensing of the vast amount of genomic information and its application for early detection of genetic diseases. The applications of antibody microarray to cancer diagnosis are growing in scope and efficiency. Enhancement  in  microarrays  miniaturization  with  the aid of nanotechnology will further  contribute to molecular diagnostics and the  development  of  personalized  medicine (Haab, 2005).
              
3.  LAB-ON- A CHIP
            Lab-on-a-chip devices are ‘miniaturized integrated laboratories’ that allow separation and analysis of biological samples. These are composed of micro-fluidic systems including micro-pumps and micro-valves integrated with microelectronic components (Griffith et al., 2005).
             Nanotechnology allows miniaturization of these devices which requires high electrical field’s strengths that can be obtained by using Nano sized electrodes and the membranes based on Nano pore separation systems. Lab-on-chip devices have rapidly evolved for applications in a number of clinical analysis operations which is fabricated on silicon or glass substrates using thin film technology and photolithography techniques. The advantages of Lab-on-chip devices are the small sample and reagent volume employed in these systems, rapid response time, less sample wastage, and prospect of developing disposable devices.

4.  DIAGNOSTIC IMAGING
        In vivo imaging is most important in diagnosis of disease which searches for the symptoms of the disease within live tissue suspected of being infected. Medical diagnostic imaging includes MRI, PET, CT, OCT, opto-acoustic or photo-acoustic tomography (OAT/PAT) and NIR imaging (Rosen et al., 2011).
        Medical research has exploited the unique properties of nanomaterials for in vivo imaging where tools and devices are being developed by using nanomaterials. Nanotechnology is having impact on this area, particularly by developing molecular imaging agents. A nanoparticle enhances favorable distribution and improved contrast in MRI and Ultrasound images. Nanomaterials containing contrast agents can greatly improve sensitivity of diagnostic imaging techniques. Nanomaterials can improve imaging techniques even at single cell before any symptoms appear (Wickline et al., 2006).
Super-paramagnetic nanoparticles are widely used as MRI contrast agent, while liquid perfluorocarbon nanoparticle and liposome are examples of ultrasound contrast agent. Optically absorbing gold nanoparticles can be used as contrast agent for opto-acoustic imaging as well as gold nanoparticles used in NIR imaging due to their lumiscence properties. Body cannot clear them due to their Nano size, which prolongs the time span for imaging. Traditional fluorophores such as organic dyes and fluorescent proteins suffer from several intrinsic problems including rapid photo-bleaching, spectral cross-talking, narrow excitation profiles, and limited brightness/signal intensity. These shortcomings can be reverted by iron oxide nanoparticles (MNP) coated with peptides specifically bind to the tumor cell which in turn enhances the images of MRI owing to its magnetic properties (Akhtari et al., 2008).  MNP-MRI allowed noninvasive, real-time quantification of pancreatic inflammation for diagnosis of autoimmune diabetes (Turvey et al., 2005).

2.3       APPLICATIONS OF NANOTECHNOLOGY IN MEDICAL DIAGNOSIS
            Nanotechnology has multiple applications which includes; Target identification and validation, animal experiment, clinical trials, early detection diagnosis and treatment of diseases, drug delivery and in toxicology which include in vivo and invitro studies.

        NANOTECHNOLOGY AND ITS APPLICATION TO CANCER.
The detection and diagnosis of cancer usually depends on changes in cells and tissues which occurs at the nanoscale level inside the cells and are detected either by physical examination or imaging expertise. Nanotechnology offers a wealth of tools to provide cancer researchers with new and innovative ways to diagnose and treat cancer.

                                     DIAGNOSIS
Nano devices such as nanowires and cantilever can provide rapid and sensitive detection cancer related molecules by enabling scientists to detect molecular changes even when they occur only in small percentage of cells.
         Cantilever is one tool with potential aid in cancer diagnosis. Nano cantilevers are tiny bard anchored at one end can be engineered to bind to molecules associated with cancer. When the cancer associated molecules binds to the cantilever it changes the surface tension causing the cantilever to bend. And by monitoring whether the cantilevers are bent and to what extent enables scientist assess whether the cancer molecules are present.




THERAPY
Nanoscale devices have the potential to improve cancer therapy and to discover new therapeutic agents.
Nano shells are miniscale beads coated with gold, these beads can be designed to absorb specific wavelength of light. The absorption of light by the Nano shells creates an intense heat that is lethal to the cells. These Nano shells can be linked to antibodies that recognizes cancer cell. Metal Nano shells which are intense near-infrared (NIR) absorbers are effective both in in vivo and invitro on human breast carcinoma cells (Hirsch et al., 2003).
       (Ramsey et al., 2005) focused on liposomes which are being investigated using the lipid based nanotechnology to carry fussed dose anti-cancer drug combinations.

            APPLICATION OF NANOTECHNOLOGY IN DRUG DELIVERY

According to (Dubin, 2004), nanotechnology help to improve the solubility and bioavailability of drugs. They also help to enhance the release rate of drug. This can be done by targeted drug delivery and controlled drug release system. A drug delivery system can convey drugs more effectively, increase patient compliance and extend product life cycle.
           Drugs tend to perform more effectively in Nano particulate form and with fewer side effects. Specific Nano sized receptors present on the surface of a cell can recognize the drug and elicit appropriate response by delivering and releasing therapy exactly wherever needed. So drugs can be loaded through encapsulation, surface attachment or entrapping.
          Nano pores acts as tiny particles for releasing drugs by making the Nano pores only slightly larger than the molecules of drugs, they can control the rate of diffusion of the molecules, keeping it constant regardless of the amount of drugs remaining inside a capsule.
         Also due to poor water solubility of drugs, therapeutic drugs can be Nano sized in the range of 100-200nm. Nanoparticles in the range of 50-100nm can easily be used in the treatment of cancer because they easily move into a tumor.
        Nanoparticles can also be used to monitor conditions, and acts as an artificial means of regulating and maintaining body own hormonal balance.

2.4    ADVANTAGES AND DISADVANTAGES OF NANOTECHNOLOGY
The use of nanotechnology led to to so many advantages and disadvantages, by curing medical issues through the use of nanoparticles/materials.

ADVANTAGES
1.  The use of nanotechnology help to protect drugs from being degraded in    the body before they reach their target.

 2. It enhances the absorption of drugs into tumors and into the cancerous cells themselves.

3. Nanotechnology allows for better control over the timing and distribution of drugs to the tissue, making it easier for oncologists to assess how well they work.

4. It prevents drugs from interacting with normal cells thus avoiding side effects.

 5. Nanotechnology helps in early diagnosis and rapid testing.

DISADVANTAGES
1.     Through the use of nanotechnology atomic weapons can now be more accessible and made to be more powerful and more destructive.

2.     Since these particles are very small, problems can actually arise from the inhalation of these minute particle, much like the problems a person gets from inhaling minute asbestos particles.

3.     Presently, nanotechnology is very expensive and developing it can cost a lot of money. It is also difficult to manufacture, which is why products made with nanotechnology are more expensive.



CHAPTER THREE
3.0                                          CONCLUSION/RECOMENDATION

           Nanotechnology is influencing more deeply on medical  research; new  and  safer  diagnostic tools  are available  which  are  enabling  us  to diagnose diseases very earlier as it onsets, and to develop  diagnostic  strategy  against  it. Forthcoming years, nanotechnology will continue to evolve and expand in many areas of human life and its achievements will be applied in medical sciences for diagnosis and patient treatment.  Nanotechnology has revolutionary opportunities to fight against many diseases  such as diabetes  mellitus, cancer, neurodegenerative  diseases;  as well  as  identifying  the  microorganisms  and  viruses associated  with  infections. Existing and conventional technologies for medical diagnosis may be reaching their confines. Nevertheless, nanotechnology would provide assistance to make diagnosis of diseases more sensitive, rapid and create diagnosis tools easier to use, allowing doctors to identify disease earlier and begin treatment earlier. Nanotechnology for medical diagnosis  is  most  innovative  and  highly specific field,  which  will  renovate  the healthcare in  near  future which  would enhance quality of life of patients. The scientific vision carried forward by nanotechnology is to open up opportunities for developing new diagnostic tools to provide the ability for people to test themselves and their health to be constantly monitored. Additionally, medical implants could take advantage of the improved knowledge on how materials like plastics and metals interact with the human body, assisting doctors to replace worn out body parts with artificial ones. Ambitious scientific progress in nanotechnology, medical diagnosis will move to a phase in which straightforward disease diagnosis; independent of physician visits and large centralized laboratories. Indeed, further novel variations and innovation in nanotechnology will continue to appear and produce new opportunities for medical diagnosis.  
      
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