Ecofriendly Synthesis Of Metformin Loaded Silver Nanoparticles Using Natural Polymers And Synthesised Starch As Stabilizing Agents

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ECOFRIENDLY SYNTHESIS OF METFORMIN LOADED SILVER NANOPARTICLES USING NATURAL POLYMERS AND SYNTHESISED STARCH AS STABILIZING AGENTS

TABLE OF CONTENTS
Title page....................................................................................................................i
Certification................................................................................................................ii
Dedication................................................................................................................. iii
Acknowledgement......................................................................................................iv
Table of contents.........................................................................................................v
Lists of Tables............................................................................................................ ix
List of figures............................................................................................................ x
Abstract..................................................................................................................... xii
CHAPTER ONE: INTRODUCTION
1.1 Nanoscience.................................................................................................. 2
1.2 Nanotechnology............................................................................................. 2
1.3 Nanomedicine ............................................................................................... 2
1.4 Nanoparticles..................................................................................................3
1.4.1 Methods of Preparation of Nanoparticles..................................................... 5
1.5. Silver nanoparticles...................................................................................... 9
1.5.1 Synthesis of silver nanoparticles .................................................................. 10
1.5.2 Reducing agents in the synthesis of silver nanoparticles………………… 27
1.5.3 Stabilizing agents in the synthesis of silver nanoparticles………………… 29
1.6 Why eco friendly (green) synthesis? ............................................................30
1.7 Characterisation of silver nanoparticles........................................................ 31
1.8 Metformin HCl............................................................................................ 35
1.9 Polymers use in this research ...................................................................... 35
1.9.1 Guar Gum..................................................................................................... 35
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1.9.2 Xanthan Gum .............................................................................................. 37
1.9.3 Starch .......................................................................................................... 37
1.9.4 Sodium Alginate .......................................................................................... 38
1.10 Objectives of Study...................................................................................... 39
CHAPTER TWO: MATERIALS AND METHODS
2.1 Materials..................................................................................................... 40
2.2 Preparation of silver nitrate ......................................................................... 40
2.3 Synthesis of AMS ....................................................................................... 40
2.4 Synthesis of Silver nanoparticles using Azadirachta indica extract… ……. 41
2.5 Characterisation of silver nanocomposites……………………………….. 41
2.5.1 UV vis spectroscopy of silver nanocomposites…………………………… 41
2.5.2 Determination of Percent yield of nanoparticles …………………………...43
2.5.3 Entrapment efficiency and loading capacity……………………………….. 43
2.5.4 Determination of Particle Size and Polydispersity Index …………………. 43
2.5.5 Differential Scanning Calorimetry and Thermogravimetric analysis …….. 44
2.5.6 Morphological Studies of nanocomposites using SEM ………………….. 44
2.6. In vitro Drug Release Studies …………………………………………….. 44
2.6.1 In vitro release kinetic evaluation ………………………………………. 45
2.7 Antimicrobial Studies of nanocomposites………………………………… 45
2.7.1 Microorganisms used ……………………………………………… ………46
2.7.2 Drugs. ……………………………………………………………………. .46
2.7.3. Preparation of Stock Samples Suspension …………………………………. 46
2.7.4 Preparation of innoculum………………………………………………… 46
2.7.5 Determination of Minimum Inhibitory Concentration …………………… 47
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2.8 Oral glucose loading animal model…………………………………………47
2.8.1 Experimental animals …………………………………………………… 48
2.8.2 Effects of nanocomposites on glucose loaded hyperglycemic rats ……… 48
CHAPTER THREE: RESULTS AND DISCUSSIONS
3.1 UV – vis Spectroscopy………………………………. …… …………….. 50
3.2 Percentage yield of nanocomposites ………………………………………… 50
3.3 Entrapment efficiency and loading capacity …………………………………. 51
3.4 Differential Scanning Calorimetry …………………………………………… 57
3.5 Thermogravimetric Analysis ………………………………………………… 65
3.6 Determination of Particle size and Polydispersity Index ……………………. 69
3.7: Morphological Studies …………………………………………………… 74
3.8 Drug Release Profiles ……………………………………………………….. 77
3.9 Time for 50 % of Drug to be released in SGF (T50)………………………….. 81
3.10 Time for 50 % of Drug to be released in SIF (T50)………………………….. 94
3.11 Time for 25 % and 75% of Drug to be released in SGF (T25 and T75 )………. 96
3.12 Time for 25 % and 75% of Drug to be released in SIF (T25 and T75 )…… … 98
3.13 Maximum Release……………………………………………………………. 100
3.13.1 Maximum Release in SGF ………………………………………………… 100
3.13.2 Maximum Release in SIF………………………………………………….. 102
3.14 Kinetics and Mechanism of Release ……………………………………… 105
3.15 Statistical Comparison of the Release Profiles of Nanocomposites using
Multiple Time Points Dissolution………………………………………… 110
3.16 Comparison of nanocomposites using Similarity Factor (F2) ………………115
3.17: Antimicrobial Studies ……………………………………………………….. 119
3.18: Effect of nanocomposites in glucose loaded hyperglycemic rats …………… 127
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CHAPTER FOUR: CONCLUSION
Conclusion ……………………………………………………………………. 127
REFERENCES 128
APPENDICES 148

CHAPTER ONE
1.0. INTRODUCTION
In recent years, there has been an exponential interest in the development of novel
drug delivery systems using nanoparticles [1]. The transition from microparticles to
nanoparticles has led to a number of changes in physical properties of materials [2]. Two of the
major factors in this are the increase in the ratio of surface area to volume, and the size of the
particle moving into the realm quantum effects predominate. The increase in the surface-area-tovolume
ratio, which is a gradual progression as the particle gets smaller, leads to an increasing
dominance of the behaviour of atoms on the surface of the particle over that of those in the
interior of the particle. This affects both the properties of the particle in isolation and its
interaction with other material. [2]
There have been tremendous developments in the field of Nanotechnology in recent
time with various technologies formulated to synthesize nanoparticles with specific
characteristics on morphology and distribution [3]. Although, there are several methods for
the synthesis of nanoparticles, they are very expensive and involve the use of toxic and
hazardous chemicals which cause danger to humans and the environment [4]. To overcome
these challenges, the eco-friendly synthesis of nanoparticles using environmentally benign
materials like Plants [5], microorganisms [4,5], seaweed [6] and enzymes [7] were employed.
It is a single step and offers several advantages such as time reducing, cost effective and Nontoxic.
Nanocrystalline silver is a known Noble metal and they have tremendous applications
in the field of Detection, Diagnostics, Therapeutics and Antimicrobial activity [8].
In general, nanoparticles offer significant advantages over the conventional drug delivery in
terms of high stability, high specificity, high drug carrying capacity, ability for controlled
release, possibility to use in different route of administration and the capability to deliver
both hydrophilic and hydrophobic drug molecules [1].
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1.1 Nanoscience
Nanoscience is the study of phenomena and manipulation of materials at atomic and
molecular levels, where properties are remarkably different from those at larger scale [11]. It
is the study of materials that display exceptional properties, functionality and phenomena due
to the influence of small dimensions. It is the science in which materials with small
dimensions exhibit new physical phenomena, collectively known as quantum effects, which
are size dependable and significantly different from the properties of large scale materials. It
is an inter disciplinary science which cuts across the areas of Physics, Chemistry, Biology
and medicine. Other disciplines affected by nanoscience include molecular biology, surface
Science, Engineering and Biotechnology.
1.2 Nanotechnology
The application of nanoscience to technology or practical devices is called
nanotechnology. Nanotechnology is the application of nanoscience to meet industrial and
commercial objectives [11]. Nanotechnology is also applied in the design, characterisation,
production and application of devices and systems by controlling shape and size at
NANOmeter scale (1- 100nm)
1.3 NANOMEDICINE
Nanomedicine is simply the application of nanotechnology to medicine or healthcare
delivery. It is the well defined application of nanotechnology in the area of healthcare and,
disease diagnosis and treatment. Nanomedicine is a relatively new field of science and
technology. By interacting with biological molecules at nano level, nanotechnology opens up
a vast field of research and application. Interactions between artificial molecular nanodevices
and biomolecules can be examined in the extracellular medium and inside the human cells.
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Working at nanoscale, allows exploiting physical properties different from those observed at
microscale such as the volume/surface ratio. The investigated diagnostic applications can be
considered for in vitro as well as for in vivo diagnosis. In vitro, the synthesized particles and
manipulation or detection devices allow for the recognition, capture, and concentration of
biomolecules. In vivo, the synthetic molecular assemblies are mainly designed as a contrast
agent for imaging [12]
A second area exhibiting a strong development is nanodrugs where nanoparticles are
designed for targeted drug delivery. The use of such carriers improves the drug
biodistribution, targeting active molecules to diseased tissues while protecting healthy ones
[12]
A third area of application is regenerative medicine where nanotechnology allows
developing biocompatible materials which support growth of cells used in cell therapy.
Nanomedicine can enhance the development of a personalized medicine both for diagnosis
and therapy.
‘There is no nanomedicine, there is nanotechnology in medicine’ (12). Even if the
expression “nanomedicine” has been widely used for a couple of years, it is more proper to
refer to “nanotechnology enabled medicine” in different subā€areas of medicine such as
diagnostics, therapy or monitoring.
1.4. Nanoparticles
According to the definition from National Nanotechnology Initiative (NNI),
nanoparticles are structures of sizes ranging from 1 to 100 nm in at least one dimension.
However, the prefix “nano” is commonly used for particles that are up to several hundred
NANOmeters in size.[11].
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Nanoparticles can also be defined as particulate dispersions or solid particles with a
size in the range of 10-1000nm. The active pharmaceutical ingredient is dissolved, entrapped,
encapsulated or attached to a nanoparticle matrix. Depending upon the method of definition,
nanoparticles, nanospheres or nanocapsules can be obtained. Nanocapsules are systems in
which the drug is confined to a cavity surrounded by a unique polymer membrane; while
nanospheres are matrix systems in which the drug is physically and uniformly dispersed [13]
Nanoparticles exhibit unique properties, which are quite different from those of larger
particles. New properties of nanoparticles related to variation in specific characteristics like
size, shape and distribution have been demonstrated [14].
The advantages of using nanoparticles as a drug delivery system include the
following [13]
1. Particle size and surface characteristics of nanoparticles can be easily manipulated to
achieve both passive and active drug targeting after parenteral administration.
2. Controlled and sustained release of the drug during the transportation and at the site of
action, altering organ distribution of the drug and subsequent clearance of the drug in order to
achieve enhanced drug therapeutic efficacy and minimal side effects.
3. Drug loading is relatively high and drugs can be incorporated into the systems without
chemical reaction.
4. Site-specific targeting can be achieved by attaching targeting ligands to particle surface.
5. The system can be used for various routes of administration including oral, nasal,
parenteral, intra-ocular etc.
6. Avoidance of coalescence leads to enhanced physical stability.
7. Reduced mobility of incorporated drug molecules leads to reduction of drug leakage.

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