DEVELOPMENT OF NANOSTRUCTURED STARCH-BASED MATERIALS FROM
NATIVE SAGO STARCH (Metroxylon Sagu)
TAY SOON HIANG
A thesis submitted
in fulfillment of the requirement for the Degree of
Doctor of Philosophy
(Physical Chemistry)
Faculty of Resource Science and Technology
UNIVERSITI MALAYSIA SARAWAK
2013
ii
DECLARATION
I hereby declare that no portion of the work referred to this thesis has been submitted in
support of an application for another degree or qualification to this or any other university or
institution of higher learning.
(TAY SOON HIANG)
Department of Chemistry
Faculty of Resource Science and Technology
Universiti Malaysia Sarawak
iii
ACKNOWLEDGEMENTS
First of all, I would like to express my thankfulness to my Almighty God, for His favour,
guidance and divine direction, which make it possible for me to complete this study.
My heartfelt gratitude is extended to my supervisor, Associate Professor Dr Pang Suh Cem,
who has tirelessly been providing me with constructive input in my thesis through his vast
wealth of academic experience, encouragement, and patience throughout my research.
Special thanks to Dr Chin Suk Fun for her guidance and encouragement in assisting me along
this challenging academic journey.
I am sincerely grateful to my dearest sisters-in-Christ, Patricia Wong and Fui Mui, for their
love, constant support and consistent prayer during my period of study. The encouragement
and prayer support of my church group are also truly appreciated.
I am also indebted to Ting Woei, a Science Officier of UNIMAS, for her meticulous care and
diligence in running the samples during the early part of my research. Many thanks to Zeti,
Shafri, Besar, Shamsuddin, Benedict and Wahab for their technical assistance and support in
my laboratory work.
The friendship, encouragement and technical support of Sze Yun, Chian Yee, Boon Hua,
Irene Foo, Siong Hwa and Fiona are also deeply appreciated. My family’s patience and moral
support have also greatly encouraged me to finish this study.
iv
I would also like to express my sincere appreciation to the Ministry of Education for
approving my study leave and granting me the scholarship which has given me this golden
opportunity to continue my study.
v
ABSTRACT
Starch-based materials are promising materials in the various biomedical applications from
targeted drug delivery, controlled drug release, to tissue engineering. The wide applications
is due to their intriguing properties biocompatibility and biodegradability as well as their
nature of being non-toxic, environmental benign, abundant and cheap. Abundant supply of
hydroxyl groups on the polysaccharide chains provide ample opportunity for the modification
of starch to prepare starch derivatives of various functionality. End products such as starch-
based hydrogels and nanoparticles could be fabricated in order to tailor their properties for
more specific fields of applications. In this research, facile methods for the synthesis of two
different major products such as starch-maleate (SM) nanoparticles and starch-maleate-
polyvinyl alcohol (SMP) hydrogels were being developed.
The first synthetic route involved the synthesis of SMP hydrogels using native sago starch
(Metroxylon sagu) as the precursor material. Starch-maleate-polyvinyl alcohol (SMP)
hydrogels were prepared by reacting polyvinyl alcohol (PVA) with maleic acid (MA)
substituted sago starch (SS). The substitution of MA and PVA onto the polysaccharide chain
of sago starch were evidenced by the FTIR spectra which showed the presence of the
carbonyl group absorption band of maleate ester, and increased intensity of the CH
stretching absorption band. The surface morphology of SMP hydrogels as revealed by SEM
micrograph was membrane-like with continuous matrices, and these samples were insoluble
in both water and alkaline aqueous solution. TGA analysis showed that the SMP hydrogel
exhibited higher thermal stability as compared to the RS, regenerated polyvinyl alcohol
(RPVA) and SM samples. SMP hydrogel regenerated by freeze-drying showed substantially
vi
higher swelling ratio than hydrogel regenerated by direct precipitation under controlled
conditions. The swelling behavior of SMP hydrogel could be easily controlled and
modulated by varying the feeding composition of precursors or the regeneration methods.
SMP hydrogel was evaluated on drug release profile studies. It showed fast release of
methylene blue as a model drug within an hour, and then the rate of drug release decreased
with time. The high potential utility of SMP hydrogels in biomedical applications is
envisaged by its biocompatibility, low toxicity, ease of preparation and low cost.
Water soluble cross-linked starch-maleate (SM) monoester gel particles from native sago
starch (Metroxylon sagu) was being synthesized. SM monoester gel was initially synthesized
by reacting sago starch with maleic anhydride instead of maleic acid in an aqueous medium,
and followed by controlled precipitation in absolute ethanol, propan-1-ol and butan-1-ol. The
substitution of maleic anhydride onto starch chains was confirmed by FTIR spectroscopy,
and the degree of substitution (DS) as determined by the back-titration method was within the
range of 0.03-0.21. By using different alcohol as the precipitating media, substituted SM of
different compositions were obtained as indicated by the relative intensities of the carbonyl
peaks in the FTIR spectra. The transformation of starch-maleate gel into cross-linked gel
particles of mean diameter 445 ± 115 nm occurred upon UV irradiation in the presence of
cerium(IV) ammonium nitrate as depicted in the SEM analyses. However, as revealed in
TEM analyses, platelet shaped nanoparticles of average length and width 36.9 ± 7.6 nm and
17.7 ± 4.8 nm respectively were formed upon drying of the SM aqueous solution. The water
absorbency and hydrophilicity of SM gel particles of DS < 0.03 was substantially lower than
SM samples of DS > 0.08.
vii
In this study, SM nanoparticles were synthesized by a different approach based on the
nanoprecipitation method. SM nanoparticles were obtained by adding SM solution dropwise
into absolute ethanol under controlled conditions. The present study had focused mainly on
modulating of the solvent and non-solvent systems in order to prepare SM nanoparticles of
different morphologies. The pH of the solvent system and the nature of surfactants being
added into the solvent system could influence the morphology of regenerated SM
nanoparticles. SM nanoparticles of discrete and spherical shape were regenerated from both
basic and acidic SM sample solution in the presence of an appropriate surfactant. SM
nanoparticles with mean diameter of about 250 nm were obtained by precipitation in absolute
ethanol in the presence of Brij 35 as the surfactant.
Lastly, curcumin which suffers from the drawback of being extremely low water solubility
and bioavailability, was loaded onto water soluble starch maleate (SM) to form curcumin-
loaded SM nanoparticles. The loading of curcumin onto SM was achieved by dissolving
curcumin and SM separately in absolute ethanol and ethanol/aqueous (40:60 v/v) mixture
respectively. Curcumin-loaded starch maleate (CurSM) were subsequently precipitated from
a homogeneous mixture of these solutions in absolute ethanol based on the solvent exchange
method. TEM analysis indicated that the diameter of CurSM nanoparticles ranged between
30 nm and 110 nm with a mean diameter of 50 nm. The curcumin loading capacity in CurSM
nanoparticle as a function of loading duration were investigated using the UV visible
spectrophotometer. The loading of curcumin onto SM increased rapidly initially with
increasing loading duration and the loading capacity was reached after 12 hours. CurSM
nanoparticles exhibited substantially higher water solubility than that of curcumin alone.
viii
Perkembangan bahan nano-struktur berasaskan kanji daripada kanji sagu asli
(Metroxylon sagu)
ABSTRAK
Bahan-bahan berasaskan kanji telah menjadi suatu bahan yang istimewa untuk kegunaan
dalam bidang perubatan yang merangkumi penghantaran dan pembebasan dadah secara
terkawal sehingga bidang tisu kejuruteraan. Kegunaan-kegunaan yang luas itu adalah
disebabkan oleh ciri-ciri yang istimewa pada kanji seperti ciri-ciri keserasian bio,
terbiodegradasi serta tidak toksik, banyak dan murah. Kumpulan hidroksil yang banyak pada
rantai polisakarida telah memberi satu laluan untuk pengubahsuaian kanji untuk
menghasilkan terbitan kanji yang pelbagai fungsi. Seterusnya hidrogel serta zarah-zarah
nano yang berasaskan terbitan kanji dapat dihasilkan untuk memenuhi kegunaan dalam
bidang tertentu. Oleh itu, dalam kajian ini, kaedah-kaedah yang mudah telah
diperkembangkan dalam sintesis dua jenis bahan yang utama iaitu zarah-zarah nano SM dan
hidrogel SMP.
Lalu sintesis pertama melibatkan sintesis hidrogel SMP dengan menggunakan kanji sagu asli
(Metroxylon sagu) sebagai bahan permulaan. Hidrogel kanji-maleat-polivinil alkohol (SMP)
telah disediakan apabila polivinil alkohol (PVA) bertindak balas dengan terbitan kanji sagu
(SS)-asid maleik (MA). Penukargantian MA pada PVA dan rantai polisakarida kanji sagu
dibukti oleh spektra FTIR yang menunjukkan kehadiran jalur serapan kumpulan karbonil
pada maleat ester dan pertambahan keamatan jalur serapan bagi C-H. Mikrograf SEM
(Imbasan Elektron Miksroskop) menunjukkan morfologi permukaan hidrogel yang
merupakan matrik-matrik membran yang berterusan. Sampel SMP juga didapati tidak boleh
larut dalam air dan alkali. Analisis termagravimetrik (TGA) menunjukkan bahawa hidrogel
ix
SMP menunjukkan kestabilan haba lebih tinggi berbanding dengan sampel-sampel
RS, RPVA dan SM. Hidrogel SMP dihasilkan secara pengeringan beku menunjukkan
nisbah pengembangan yang jauh lebih tinggi daripada hidrogel yang dihasilkan secara
pemendakan terus. Sifat-sifat pengembangan hidrogel SMP boleh dikawal dan diubah
dengan mudah dengan mempelbagaikan komposisi bahan-bahan persediaan atau kaedah
penghasilan semula sampel. Hidrogel SMP dinilaikan dari segi keupayaannya dalam
pembebasan dadah secara terkawal. Metilena biru digunakan sebagai model dadah dalam
kajian ini telah menunjukkan pembebasan yang cepat dalam tempoh satu jam yang pertama
dan kemudian kadarnya berkurang dengan masa. Keupayaan SMP hidrogel digunakan
dalam bidang perubatan dapat ditunjukkan oleh keserasian bio, ketoksikan yang rendah,
persediaan yang mudah serta kos yang rendah.
Zarah-zarah gel kanji-maleat monoester yang bertaut- silang dan boleh larut dalam air
daripada kanji sagu asli (Metroxylonsagu) telah disintesiskan. Pada mulanya gel
monoester SM disintesiskan melalui tindak balas kanji sagu dengan maleik anhidrida selain
daripada asid maleik dalam satu medium akues, diikuti oleh pemendakan dalam etanol
mutlak, propan-1-ol and butan-1-ol. Penggantian maleik anhidrida ke atas rantai-
rantai kanji telah ditunjukkan oleh spektroskopi FTIR , dan darjah penukargantian (DS)
ditentukan dengan menggunakan kaedah pentitratan balik dan didapati dalam julat 0.03-
0.21. Dengan menggunakan alkohol berbeza sebagai ejen pemendakan, SM dengan
komposisi terbitan SM yang berbeza diperoleh seperti yang ditunjukkan oleh perbezaan
keamatan relatif bagi jalur karbonil dalam spektra FTIR. Analisa SEM menunjukkan
transformasi gel maleat kanji kepada zarah-zarah gel sebanyak 445 ±115 nm apabila SM
ditaut-silang oleh sinaran UV dengan kehadiran ammonium serium(IV) nitrat.
x
Bagaimanapun, seperti yang ditunjukkan oleh analisa TEM, zarah-zarah nano SM yang
berbentuk platelet dengan panjang dan lebar purata sebanyak 36.9 ± 7.6 nm dan 17.7 ± 4.8
nm masing-masing diperoleh setelah pengeringan larutan akues SM. Kedayaserapan air dan
sifat hidrofilik bagi gel SM dengan DS < 0.03 adalah jauh lebih rendah daripada
SM dengan DS > 0.08.
Dalam kajian ini, zarah-zarah nano SM telah disintesis melalui pendekatan yang berlainan
secara kaedah pemendakan. Zarah-zarah nano SM diperoleh melalui penambahan larutan
SM titis demi titis ke dalam etanol mutlak di bawah keadaan yang terkawal. Kajian ini
tertumpu kepada jenis-jenis pelarut dan bukan pelarut untuk menyediakan zarah-zarah nano
SM dengan morfologi yang berbeza. Pelarut yang berlainan pH dan jenis surfaktan yang
berbeza ditambah ke dalam sistem pelarut boleh mempengaruhi morfologi zarah-zarah nano
SM. Zarah-zarah nano SM yang diskrit dan berbentuk sfera dapat dihasilkan dalam larutan
beralkali SM atau dalam keadaan asid dengan kehadiran surfaktan tertentu. Zarah-zarah nano
SM dengan diameter purata sebanyak 250 nm dapat diperoleh secara pemendakan dalam
etanol mutlak dengan kehadiran Brij 35 sebagai surfaktan.
Akhir sekali, kunyit yang mempunyai keterlarutan air yang sangat rendah dan
keterbiosediaan dapat dimuatkan pada kanji-maleat untuk membentuk zarah-zarah nano SM
yang dimuatkan dengan kunyit. Pemuatan kunyit ke atas SM telah dicapai apabila kunyit
dan SM masing-masing dilarut dalam etanol mutlak dan etanol /berair yang mempunyai
nisbah isipadu sebanyak 40:60. Zarah-zarah nano kanji-maleat yang dimuatkan dengan
kunyit (CurSM) diperoleh apabila larutan homogen CurSM dimendakkan dalam etanol
mutlak berdasarkan kaedah pertukaran pelarut. Analisa TEM menunjukkan bahawa julat
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diameter bagi zarah-zarah nano CurSM berada dalam lingkungan antara 30 nm dan 110 nm
dan diameter purata sebanyak 50 nm. Keupayaan muatan kunyit dalam zarah-zarah nano
CurSM sebagai fungsi masa telah dikaji dengan menggunakan spektrofotometer sinaran
ultraungu visible (UV). Pemuatan kunyit ke atas SM bertambah dengan banyak dengan
tempoh muatan pada permulaan dan kapasiti maksima muatan telah dicapai selepas 12 jam.
Didapati zarah-zarah nano CurSM menunjukkan keterlarutan air yang lebih tinggi daripada
kunyit asli.
xii
TABLE OF CONTENTS
Page
DECLARATION ii
ACKNOWLEDGEMENTS iii
ABSTRACT v
ABSTRAK viii
TABLE OF CONTENTS xii
LIST OF TABLES xvii
LIST OF FIGURES xviii
ABBREVIATIONS xxi
LIST OF PUBLICATIONS xxv
1.0 CHAPTER ONE: GENERAL INTRODUCTION 1
2.0 CHAPTER TWO: LITERATURE REVIEW 6
2.1 Starch 6
2.1.1 Structure of starch granule 6
2.1.2 Amylose and amylopectin 7
2.1.3 Gelatinisation and gel formation 9
2.1.4 Starch solubilisation 10
2.2 Starch Ester 11
2.2.1 Mechanisme of esterification 11
2.2.2 Heterogenenous esterification of starch 16
2.2.3 Homogenenous esterification of starch 18
2.2.3.1 Type of catalyst 18
2.2.3.2 Temperature 21
xiii
2.2.3.3 Type of solvent system 21
2.2.3.4 Type of cyclic acylating agent 22
2.2.4 Regioselective esterification of starch 23
2.3 Starch-based Hydrogel 24
2.3.1 Physcial cross-linking 25
2.3.2 Chemical cross-linking 28
2.3.2.1 Condensation reaction 28
2.3.2.2 Free radical reaction 31
2.3.3 Incorporation of synthetic polymer 33
2.3.4 Swelling behaviour of hydrogel 34
2.4 Polysaccharide Nanoparticles 36
2.4.1 Fabrication of polysaccharide nanoparticles 37
2.5 Conformation of Polysaccharide Chains in Solution 45
3.0 CHAPTER THREE: STARCH-MALEATE-POLYVINYL ALCOHOL
HYDROGELS WITH CONTROLLABLE SWELLING BEHAVIOURS
3.1 Introduction 48
3.2 Materials and Methods 50
3.2.1 Materials 50
3.2.2 Preparation of starch-maleate-PVA (SMP) hydrogel 50
3.2.3 Characterisation of starch-maleate-PVA hydrogel 52
3.2.4 Drug loading and release profile 53
3.3 Results and Discussion 54
3.3.1 Synthesis and characterisation of SMP hydrogels 54
3.3.2 Swelling behaviour of SMP hydrogel 61
3.3.3 Drug release behaviour of drug_loaded SMP hydrogel 67
xiv
3.4 Conclusions 71
4.0 CHAPTER FOUR: SYNTHESIS OF STARCH-MALEATE MONOESTERS
FROM NATIVE SAGO STARCH
4.1 Introduction 72
4.2 Materials and Methods 74
4.2.1 Materials 74
4.2.2 Synthesis of starch-maleate monoester gels 75
4.2.3 Preparation of cross-linked starch-maleate monoester gel
particles (CSM) 76
4.2.4 Characterisation of SM and CSM 77
4.3 Results and Discussion 79
4.3.1 Evidences of maleate substitution on starch molecules 79
4.3.2 Effect of synthesis parameters 80
4.3.3 Effect of precipitating media 82
4.3.4 Moisture absorbency of SM 83
4.3.5 Effect of UV irradiation 85
4.3.6 Morphology of SM in aqueous medium 89
4.4 Conclusions 90
5.0 CHAPTER FIVE: A FACILE APPROACH FOR CONTROLLED
SYNTHESIS OF HYDROPHILLIC STARCH-BASED NANOPARTICLES
FROM NATIVE SAGO STARCH
5.1 Introduction 92
5.2 Materials and Methods 94
5.2.1 Materials 94
5.2.2 Synthesis of starch-maleate monoester (SM) 94
xv
5.2.3 Preparation of SM nanoparticles 95
5.2.4 Characterisation of SM nanoparticles 96
5.3 Results and Discussion 96
5.3.1 Structure of SM nanoparticles 96
5.3.2 Morphological characterisation of SM nanoparticles 98
5.3.2.1 Effect of precipitating medium composition 98
5.3.2.2 Effect of solvent pH 99
5.3.2.3 Effect of water adsorption 101
5.3.2.4 Effect of surfactants 102
5.4 Conclusions 105
6.0 CHAPTER SIX: SYNTHESIS OF CURCUMIN-LOADED STARCH-
MALEATE (CurSM) NANOPARTICLES
6.1 Introduction 107
6.2 Materials and Methods 108
6.2.1 Materials 108
6.2.2 Preparation of curcumin-loaded starch-maleate (CurSM) 109
6.2.3 Preparation of CurSM nanoparticles 110
6.2.4 Curcumin loading capacity of SM nanoparticles 110
6.2.5 Confocal Scanning Microscope analysis 110
6.2.6 TEM analysis 110
6.3 Results and Discussion 111
6.3.1 Preparation of curcumin-loaded starch-maleate 111
6.3.2 Solubility of CurSM nanoparticles 113
6.3.3 UV-Visible spectra of CurSM 114
6.3.4 Particle size distribution of CurSM nanoparticles 115
xvi
6.3.5 Loading efficiency of curcumin 117
6.4 Conclusions 118
7.0 CHAPTER SEVEN: CONCLUSIONS 119
REFERENCES 122
xvii
LIST OF TABLES
Table 2.1 Native starches of different Origins with their respective amylose content
(Young, 1984).
Table 2.2 Gelatinisation temperature ranges of native starches (Whistler & Daniel,
2005).
Table 2.3 Different types of common cross-linkers in the cross-linking of starch.
Table 2.5 The different types of polysaccharides-based nanoparticles and their
applications.
Table 3.1 The feed weight ratios of native sago starch, maleic acid and PVA for the
synthesis of various compositions of SMP hydrogels.
Table 3.2 The swelling ratio of SMP hydrogels prepared by different regeneration
methods and at various swelling medium conditions.
Table 4.1 Synthesis parameters and reaction efficiency in the preparation of SM
monoester samples.
xviii
LIST OF FIGURES
Figure 2.1 (a) Schematic representation of starch granule with amorphous and crystalline
lamellae. (b) Orientation of amorphous and crystalline layers in amylopectin
molecules (Jenkins & Donald, 1995).
Figure 2.2 Chemical structure of: (a) amylose, and (b) amylopectin.
Figure 2.3 Schematic representation of esterification of starch molecule which follows
the Fisher Esterification mechanism.
Figure 2.4 Schematic representation of esterification of starch which follows the Steglich
Esterification mechanism.
Figure 2.5 Structural formula of DMAP.
Figure 2.6 Chemical reaction mechanisms for starch acetylation and maleation in alkaline
conditions (Xu et al., 2004).
Figure 2.7 Structural formula of an AGU.
Figure 2.8 Mechanisms of in situ physical gelation based on charge interactions with an
oppositely-charged polymer or an oppositely-charged small molecule cross-
linker (Hoare & Kohane, 2008).
Figure 2.9 Mechanism of in situ physical gelation driven by hydrophobic interactions
(Hoare & Kohane, 2008).
Figure 3.1 Schematic representation of the cross-linking reaction between starch and
PVA molecules by maleic acid.
Figure 3.2 FTIR spectra of (a) native sago starch; (b) sago starch-maleate; (c) sago
starch/PVA, (d) and (e) SMP hydrogels prepared by direct precipitation and
freeze drying, respectively.
Figure 3.3 The TGA thermograms of regenerated starch, regenerated PVA, SM and SMP
hydrogel samples.
Figure 3.4 SEM micrographs of (a) native sago starch; (b) SM, and (c) SMP hydrogel.
Figure 3.5 SEM micrographs of SMP hydrogels prepared at various cross-linking
reaction timesand regeneration methods. (a) 2 hours; direct precipitation, (b) 4
hours; direct precipitation, and (c) 4 hours; freeze-drying; (Magnification:
1000x).
Figure 3.6 Effect of feeding composition on the swelling ratio of the SMP hydrogel, (a)
mole fraction of various precursors, and (b) mole ratio of PVA/MA.
xix
Figure 3.7 Effect of maleic acid content in the feed on the swelling ratio of the SMP
hydrogels before and after water extraction.
Figure 3.8 UV Visible spectra of the MB released from SMP hydrogels in UP water at
25oC at different time intervals.
Figure 3.9 The calibration graph of standard methylen blue in UP water at 25oC.
Figure 3.10 The MB released from SMP hydrogels in UP water at 25oC at different time
intervals.
Figure 3.11 The cumulative release profile of MB to the square root of the release time for
MB_ loaded SMP hydrogels in distilled water at 25oC.
Figure 4.1 Schematic representation of the reaction between starch and maleic anhydride.
Figure 4.2 FTIR spectra of (a) maleic anhydride, (b) native sago starch, and (b) starch-
maleate monoester (DS 0.21) which is precipitated using ethanol.
Figure 4.3 FTIR spectra of starch-maleate monoester (DS = 0.21) precipitated in different
precipitating media (a) ethanol, (b) ethanol:butan-1-ol (1:1), and (c) propan-2-
ol.
Figure 4.4 Effect of degree of substitution (DS) on the moisture absorbency of starch-
maleate monoester (precipitation with ethanol) with duration of equilibration
at relative humidity of 100%.
Figure 4.5 FTIR spectra of starch maleate monoester (DS = 0.21) (a) before, and (b) after
UV irradiation, after precipitation with ethanol.
Figure 4.6 SEM micrographs of starch maleate monoester (a) before, and (b) after UV
irradiation.
Figure 4.7 Histogram showing the size distribution of CSM spherical gel particles (DS of
SM = 0.21) formed after UV irradiation.
Figure 4.8 TEM micrographs of starch-maleate monoester when dispersed in aqueous
medium. The scale bar is 50 nm.
Figure 5.1 FTIR spectra of starch-maleate regenerated in (a) absolute ethanol only, and
1 % surfactant of (b) SDS, (c) SDBS, and (d) CTAB, in the sample solution.
Figure 5.2 SEM micrographs of (a) native sago starch nanoparticles, and (b) SM
nanoparticles regenerated by precipitation in absolute ethanol.
xx
Figure 5.3 SEM micrographs of SM samples regenerated using different volume ratios of
SM solution to absolute ethanol of (a) 1:2, (b)1:3, (c) 1:4, and (d) 1:5
(precipitated by adding 1% of SM sample solution at pH 5 drop-wise into
absolute ethanol).
Figure 5.4 SEM micrographs of SM nanoparticles regenerated from (a) alkaline solvent
medium, and (b) acidic solvent medium, by precipitation in absolute ethanol
(arrows show spherical nanoparticles).
Figure 5.5 Schematic representation of the conformation of starch-maleate samples: (a)
anions in aqueous media, (b) anions during solvent exchange, (c)
nanoparticles.
Figure 5.6 SEM micrograph of regenerated SM nanoparticles after being rinsed twice
only with absolute ethanol (arrows show gelation of nanoparticles).
Figure 5.7 SEM micrographs of starch-maleate samples regenerated in 1 % of different
surfactants (a) CTAB,(b) B35, (c) SDBS, (d) SDS, (e) T80, and (f) PEG, in
sample solution. (The volume ratio of SM solution to absolute ethanol used in
SM regeneration was 1:5 at ambient temperature).
Figure 5.8 Mean particle sizes of SM samples regenerated in absolute ethanol containing
1 % of different surfactants in sample solution. (Volume ratio of 5% of aSM
solution to absolute ethanol was 1:5). aSynthesis parameters of SM: Molar
ratio of AGU: MAH = 1:1.5; starch concentration = 8%; Mol of NaOH = 0.01
mol; Reaction temperature = 100oC; Reaction time = 1 hour.
Figure 6.1 Confocal laser scanning micrographs of (a) CurSM dispersed in absolute
ethanol, (b) SM without curcumin.
Figure 6.2 Schematic representation of the interaction between curcumin molecules and
SM molecules via hydrogen bonding.
Figure 6.3 Pictures of CurSM samples in (a) absolute ethanol, and (b) water.
Figure 6.4 UV-visible spectra of CurSM in 0.4 % CurSM aqueous solution.
Figure 6.5 (a) Particles size distribution of CurSM nanoparticles prepared with a loading
duration of 14 hours at 50-60oC. (b) TEM micrograph of CurSM
nanoparticles precipitated in absolute ethanol at 1:4 volume ratio of 1%
CurSM solution to absolute ethanol. The bar line is 100 nm.
Figure 6.6 The loading profile of curcumin onto starch-maleate as function of loading
duration. (0.4% of CurSM solution).
xxi
ABBREVIATIONS
µm micrometer
α alpha
% percentage
w/w weight to weight
o degree
C celsius
DMSO dimethylsulfoxide
DMAc dimethylacetate
v/v volume to volume
SN2 nucleophilic substitution, second order
DCC 4-N,N-dicyclohexylcarbodiimide
DHU dicyclohexylurea
DMAP 4-(dimethylamino)pyridine
M molar
NaOH sodium hydroxide
N normality
OH hydroxyl
KOH potassium hydroxide
DS degree of substitution
hr hour
min minute
MAH Maleic anhydride
LiCl lithium chloride
AGU anhydroglucose unit
xxii
PEG polyethylene glycol
PVA polyvinyl alcohol
PVAc polyvinyl acetate
STMP sodium trimetaphosphate
STPP sodium tripolyphosphate
EPI epichlorohydrin
POCl3 phosphorus oxychloride
UV ultraviolet
C carbon
H hydrogen
60
Co cobalt-60
FTIR Fourier Transform Infrared
XRD X-Ray Diffraction
DNA deoxyribonucleic acid
MWCO molecular weight cut-off
nm nanometer
M molar
SPCL Starch-poly--caprolactone
DMF N,N-dimethylformamide
THF tetrahydrofuran
Dex dextran
mPEG methyoxy polyethylene glycol
PLGA polylactic-co-glycolic acid
DPP dextran propionate pyroglutamate
ALG alginic acid
PDEA poly(2-(diethylamino) ethyl methacrylate)
xxiii
beta
SS sago starch
MA maleic acid
AR analar grade
MΏ milliohm
SMP starch-maleate polyvinyl alcohol
SM starch-maleate
KBr potassium bromide
cm-1
per centimetre
g gram
mL millilitre
SR swelling ratio
MB methylene blue
UP ultra-pure
TGA thermagravimetric analysis
RS regenerated starch
RPVA regenerated polyvinyl alcohol
SEM scanning electron microscopy
CSM cross-linked starch-maleate
W watt
kV kilovolt
Dn mean particle diameter
ni number of particles
di
diameter
HCl hydrochloric acid
mol mole
xxiv
RH relative humidity
RE reaction efficiency
TEM transmission electron microcope
SDS sodium dodecyl sulphate
Tween 80 T80
Brij 35 B35
CTAB cetyl trimethylammonium bromide
SDBS sodium dodecyl benzene sulphonate
rpm rate per minute
CurSM curcumin-loaded starch-maleate
CLSM confocal laser scanning microscope
