International Research Journal of Plant Science (ISSN: 2141-5447) Vol. 2(3) pp. 078-086, March, 2011
Available online http://www.interesjournals.org/IRJPS
Copyright © 2011 International Research Journals
Full length Research Paper
Swelling behaviour of konkoli (maesopsis eminii)
galactomannan hydrogels.
Nkafamiya II, Barminas JT, Aliyu BA and Osemeahon SA.
Federal University of Technology, Yola Adamawa State Nigeria
Accepted 21 March, 2011
To utilize konkoli (maesopsis eminii) seeds (KS), a medicinal natural polysaccharide, for development
of a novel hydrogels for use in drug delivery, we prepared hydrogels by varying the concentrations of
both the KS and borax (BX) using different ratios. This paper discusses the swelling responses of the
hydrogels in different mediums [distilled water (DW), pH2.2 and pH7.4]. Percentage swelling (PS) has
been observed to be increasing with increase in the concentration of KS and keeping the
concentration of BX constant. On varying the concentration of BX and keeping the one of KS constant,
it was observed that PS increases with decrease in concentration of BX. By changing the swelling
medium from DW to pH2.2 and pH7.4, the PS increases abruptly, this indicates the smart behaviour of
the hydrogels. For all the mediums, maximum PS was observed in pH7.4. These observations indicate
that these hydrogels are pH sensitive and have potentials for use in colon specific drug delivery.
Key words: Konkoli, hydrogel, swelling, pH.
INTRODUCTION
Hydrogels are hydrophilic, three – dimensional networks
that possess the ability to swell in aqueous media without
dissolution in response to changes in their external
environment (Cauich- Rodriguez et al, 2001 and Baljit et
al., 2007a). For drug delivery, among hydrophilic
polymers, natural polysaccharides are the choice material
due to their nontoxicity and acceptance by regulatory
authorities (Sumthi and Ray, 2002). For example,
hydrogel from tamarind has been used for drug release
due
to
non-carcinogenicity,
mucoadhesivity,
biocompatibility, high drug holding capacity and high
thermal stability (Sumathi and Ray, 2002). These
polymeric networks are increasingly being used in variety
of biomedical applications because of their similarities to
living tissue. Like living tissue, they have a soft rubbery
nature and allow the permeation of low molecular weight
species (Sumathi and Ray, 2002: Tommansina et al,
2007).
Hydrogels usually exhibit different degrees of swelling
depending on their composition and molecular structure.
In addition, there is a growing interest in the group of
hydrogels that are responsive to changes in their
*Corresponding author Email: iliyankafamiya@yahoo.com
environment such as pH, temperature, or ionic strength.
Hydrogels show significant variation in swelling as a
result of external changes such as pH and temperature
have been investigated for a wide range of application
namely controlled release, pH-specific membrane
separation, purification of pharmaceutical products,
solution separation and solvent recovery (CauichRodriguez et al., 2001). The volume phase transition as a
response to different stimuli makes these materials
interesting objects of scientific observations and useful
materials for use in advanced technologies (Baljit et al.,
2007a). These hydrogels are mostly obtained from
seeds of indigenous leguminous plants. These plants can
be both cultivated or found in the wild. In this study, the
hydrogels used are obtained from konkoli (Maesopsis
eminii) a wild plant.
Konkoli seed gum (KSG) is a galactomannan obtained
from the seed of konkoli plant scientifically identified as
maesopsis eminii, commonly called musizi in Tanzania
(Hall, 1995; Joker, 2000; Rugalema et al, 1994), but
locally it is known as ‘konkoli’ in North Eastern Nigeria.
KSG is widely used as thickeners in soup and traditional
baked food products in Nigeria, primarily because of its
high viscosity, binding and swelling propensity (Barminas
and Eromosele, 2002; Osemeahon et al., 2008).This
plant is a large Africa tropical forest tree introduce to
Nkafamiya et al. 079
various parts of the tropics for timber production or as a
shade tree (Barminas, 2004). In Nigeria, this plant grows
in the wild in the east, south and middle belt of the
country (Aliyu, 2002; Osemeahon, 2003; Osemeahon et
al, 2008). It’s shoots greenish flowers around April and
may and bears fruits which get matured around August
and September as they become publish black containing
a very hard seed. The seed are normally removed from
the dry fruits and ground into fine powder and may be
constituted in hot or cold water and used in the
preparation of soups and other traditional baked foods
(Osemeahon, 2003; Osemeahon et al., 2008)
Recently there is a marked thrust on research activities
related to the use of natural polysaccharides for the
development of hydrogels as colon specific drug delivery
devices. These include chemically or physically
crosslinked polysaccharides, such as carboxymethyl
cellulose (Bajpai and Mishra, 2004; Baljit et al., 2007a),
starch (Bajpai and Saxena, 2004), Chitin (Mahdavinia et
al., 2004), dextran (Chiu et al., 1999; Kim and Oh, 2005),
guar gum (Gilko et al., 1998; Prasad et al., 1998; Xiuyu et
al., 2006) and psylluim (Baljit et al., 2007a). The rational
for the development of a polysaccharide-based delivery
system for colon is the presence of large amount of
polysaccharidases in the human colon, as the colon is
inhabited by a large number and variety of bacteria,
which secrete many enzymes (Baljit et al., 2007a)
Interests have been generated by many researches on
hydrogels from konkoli and up to now no scientific
information is currently present on its use in drug
delivery. This study was therefore undertaken to find a
novel hydrogel in addition to the existing once for the use
in drug delivery as the drug delivery systems achieve
more effective therapies while eliminating the potential of
both under and over dosing, maintenance of drug levels
with a desired range, and the need for fewer
administration of drug.
MATERIAL AND METHODS
solutions and stirred with a glass rod to form a gel (that is 6.5g/2.6g
konkoli/borax ration). The gel was then cast on a clean glass
surface and dried over a period of 48 hours. Using the same
procedure, different hydrogels were formed using different
konkoli/borax ratios as indicated in Table 1(varying both the
concentrations of galactomannan and borax). The different
hydrogels formed were then designated with symbols with respect
to galactomannan/ borax as indicted.
Swelling measurement behaviour of hydrogels.
The modified “Tea bag” method by Osemeahon et al., (2003) was
employed. A transparent polyethylene bag was employed here and
instead of hanging the bag to drain off, a micro-syringe was used to
suck- away excess solution. The method entailed weighing 0.1 g of
each of the samples into a weighed polyethylene bag and
reweighed again. 10ml of distilled water was added to the
polyethylene bag with the sample inside and hermetically sealed.
The bag with its content was then left undisturbed at room
temperature (270C) and at different time intervals, excess solution
was carefully sucked out after a specified time is reached. The bag
with the wet was reweighed again.
The percentage absorption (water uptake) was calculated using the
relation:
Absorption/water uptake (%) = (w2 – w1/wo) x 100
Where: w2 = weight of the wet bag plus sample
w1 = weight of the dry bag plus sample
W o = weight of the original sample
The swelling measurements for each system were repeated five
times. The mean of the result were presented in all the figures.
Preparation of buffer solution
This was done according to standard method described by Baljit et
al., 2007b. That is pH7.2 was prepared by taking 50 mL of 0.2M
KCl and 7.8 mL of 0.2N HCl in volumetric flask to make volume
200mL with distilled water. 0.2 M KCl solution was prepared by
dissolving 14.911 g of KCl in distilled water to make volume
1000mL with distilled water. Buffer solution of pH7.4 was prepared
by taking 50mL of 0.2M KH2 PO4 and 39.1 mL of 0.2N NaOH in
volumetric flask to make volume 200mL with distilled water. 0.2M
KH2 PO4 was prepared by dissolving 27.218g of KH2PO4 in distilled
water to make volume 1000mL with distilled water. pH2.2 and
pH7.4 were chosen because there are the pH of gastrointestinal
tract and the large intestine (Baljit et al., 2007b; Orienti et al., 2001)
and this study also intended to know the swelling of these
hydrogels in these parts.
Materials
Konkoli seeds (Maesopsis eminii) were obtained from Bayalse
Local Government Area of Taraba State. The seeds were cleaned
to remove dirt, sun-dried for three days and finally ground in an
electric mill (National Food Drinder, Model MK308, Japan). Borax,
KCI, HCl, KH2PO4 and NaOH were obtained from British Drug
House (BDH). The chemicals were of analytical grade and were
used as provided.
Fourier transform infrared spectroscopy (FTIR)
FTIR was carried out to study the modified nature of the hydrogel
obtained from konkoli seeds. The FTIR spectra’s were recorded in
KBr pellets on Perkin-Elmer (FTIR 8400S Shimadzu).
Statistical analysis
Methods
Preparation of Hydrogel Systems
25ml portion of distilled water was transferred into 250ml glass
beaker and mixed thoroughly with 6.5 g konkoli powder to form a
very viscous solution. Then 2.6 g of borax was added to these
Statistical analysis was performed by one- way analysis of variance,
and differences between means were tested using Ducan’s multiple
range tests. P-values of < 0.05 were considered to be significant
following Steel and Torric procedures (1980) and Rui et al., (2007).
080 Int. Res. J. Plant Sci.
Table 1. Blend ratio of galactomannan-borax system
K/borax (w/v)
6.5g/2.6g
5.2g/2.6g
3.9g/2.6g
2.6g/2.6g
6.5g/3.25g
6.5g/4.33g
RESULTS AND DISCUSSION
Results
Discussion
Fourier transform infrared spectroscopy (FTIR)
FTIR spectra of polymeric networks were recorded to
study the modification of the konkoli hydrogel (Fig. 1a,
and b). The absorption band at 3435.34 cm-1 can be
ascribed to –OH stretching which indicated association in
the polymeric networks. FTIR absorption bands due to C
= O stretching of amide has been witnessed at 1654.01
-1
-1
cm in modified hydrogel. 1358.90 cm peak due to NH
-1
and CH in plane bending, 823.63 cm peak due to NH
and CH out of plane bending of amide and 1016.52 cm-1
peak due to
C – O stretching of carboxylic acid has been observed
apart form usual peaks in konkoli hydrogel.
Swelling behaviour of hydrogels
The chemical structure of the polymer affects the swelling
ratio of the hydrogels which is directly related to loading
of drug to the polymers and release of drug from the
polymeric matrix. The chemical structure depended upon
composition of the polymeric matrix i.e the crosslinking
ratio. The higher the crosslinking ratio, the more
crosslinking agent is incorporated in the hydrogels
structure. Highly crosslinking hydrogels have a tighter
structure, and will swell less compared to the same
hydrogels with lower crosslinking ratios. Crosslinking
hinders the mobility of the polymer chain, hence lowering
the swelling ratio. Swelling of environmentally-sensitive
hydrogels can be affected by specific stimuli. In the
hydrogels systems, absorption of water from the
environment changes the system and thus the drug
release kinetics (Baljit et al., 2007a).
Figure 2 presents the swelling behaviour of hydrogels
on increasing the concentration of KG and keeping the
Ratio
2.5:1
2:1
1.5:1
1:1
2:1
1.2:1
Symbol
BG1
BG2
BG3
BG4
BG5
BG6
concentration of the BX constant. The result shows that
the swelling ratio increases with increase in time and also
increase with increase in the concentration KG ratio. This
is because on keeping the concentration of borax (i.e
crosslinking agent) constant and increasing the
concentration of KG, the structure becomes less tight and
absorbs more water. All the hydrogels absorbs water but
hydrogel
formulated
with
6.5/2.6
(w/w)
galactomanna/borax ratio absorbed more water between
5-9 hours. The order of water uptake is KG4< KG3 <KG2
<KG1 with significant differences in swelling values (P <
0.05). The hydrogels absorbed water in an increasing
order from 1-5 hours but decreased at 6 hour and then
increases from 7-9 hour except KG1 which decreases at
7 hour and again increases from 8-9 hour. This is due to
the fact that the structures (KG2, KG3, KG4) have less
KG concentration than KG1. Among all the hydrogels the
one formulated with 6.5/2.6 (w/w) gives better results
since it absorbed more water and start losing its network
structure at 7 hour instead at 6 hour compared to the
other hydrogels. With this result it is clearly indicated that
KG1 would give better water uptake followed by KG2.
Figure 3: shows the result for increasing concentration
of BX and keeping the one of KSG constant. From this
Figure KG5 absorbed more water than KG6 (P < 0.05).
This is due to the fact that KG6 has more concentration
of the crosslinking agent thereby leading to tight structure
and swell less. KG5 start losing its network structure at 7
hour and KG6 at the 6 hour, which indicates that KG5 is
better in terms of swelling and possible drug delivery.
Effect of pH on swelling of hydrogels
Figures 4-9 presence the effect of pH on swelling of
hydrogels prepared with different concentrations of KG
with significant differences in swelling values (P < 0.05).
The swelling for KG1, KG2, KG3, and KG4 (Varying
concentration of KG and keeping the concentration of
borax constant) are given in Figures 4-7 respectively.
In all the figures, it was observed that PS increases
with change of the swelling medium from distilled water to
pH7.2 and pH7.4. It has been also observed from all the
figures that PS of pH7.4 was more compared to the
pH2.2 and the distilled water. This is due to the fact that
Nkafamiya et al. 081
A
B
Figure 1 (a) FTIR of konkoli hydrogel (b) FTIR spectra of modified konkoli hydrogel
1000
KG1
900
KG2
PercentageSw
elling
800
KG3
700
KG4
600
500
400
300
200
100
0
0
2
4
6
Time (hrs)
Figure 2. Effect of increasing KG on swelling (% Distilled water)
8
10
082 Int. Res. J. Plant Sci.
900
800
KG5
KG6
Percentage Swelling
700
600
500
400
300
200
100
0
0
2
4
6
8
10
Time (Hrs)
Figure 3. Effect of increasing Borax on swelling (% Distilled water)
1000
900
Percentage swelling
800
DW
pH2.2
700
pH7.4
600
500
400
300
200
100
0
0
2
4
6
8
10
Time (hour)
Figure 4 : Effect of pH on Swelling behaviour KG1
Figure 4. Effect of PH on swelling behavior KG1
at lower pH values the –CONH2 groups do not ionizes
and keep the network at its collapse state. At high pH
value it gets partially ionizes, and the charged –COO
groups repel each other, leading to increase in swelling of
the polymer. These observations indicate that these
hydrogels are pH sensitive and hence have potential for
use in colon specific drug delivery devices. Similar
observation was reported by Balijt and coworkers during
syntheses, characterization and swelling response of pH
sensitive psyllium and polyacrylamide based hydrogels
for the use in drug delivery (I) (Baljit et al., 2007a). Baljit
and coworkers again reported the same during the
release dynamic of salicylic acid and tetracycline
hydrochloride from the psyllium and polyacrylamide
Nkafamiya et al. 083
900
800
DW
Percentage Swelling
700
pH2.2
600
pH7.4
500
400
300
200
100
0
0
2
4
6
8
10
Time (hours)
Figure 5. Effect PH on swelling of KG2
900
800
Percentage Swelling
700
600
500
400
DW
300
pH2.2
pH7.4
200
100
0
0
2
4
6
8
10
Time (Hours)
Figure 6. Effect of swelling on KG3
based hydrogel (II) (Baljit et al., 2007b). Also, it is
reported that the swelling of microgels, prepared with
grafting of poly (AAm) onto guar gum, increases when
the pH of the medium changes from acid to alkaline
because of the saponification of the –CONH2 to the –
COOH group (Soppimath et al., 2001).
For varying concentration of borax and keeping the
concentration of KG constant, are presented in Figures 89. Maximum PS was also observed in the medium of
pH7.4. From the forgone discussion, these hydrogels
have potentials to compete with other hydrogels reported
084 Int. Res. J. Plant Sci.
800
700
P e r c e n t a g e S w e llin g
600
500
DW
400
pH2.2
pH7.4
300
200
100
0
0
2
4
6
8
10
Time (hours)
Figure 7. Effect of swelling on KG4
by Sumathi and Ray (2002), Balijt et al., (2007a) and
Tommasina et al., (2007).
CONCLUSION
The swelling of the hydrogels is affected by concentration
of polymer in the polymeric networks and nature of the
swelling medium (pH). The swelling of the hydrogels
increases by changing the swelling medium from DW to
pH7.2 and pH7.4. This indicates the intelligent nature of
polymers. Therefore KS when modified with BX, result in
the formation of the pH sensitive hydrogels and have
potential to use as colon specific drug delivery devices in
addition to the existing once. Though konkoli seeds are
used as thickeners in soup and traditional baked food
Nkafamiya et al. 085
1000
900
Percentage Swelling
800
700
600
500
400
DW
300
pH2.2
pH7.4
200
100
0
0
2
4
6
8
10
Time (Hour)
Figure 8: Effect of Swelling on KG 5
Figure 8. Effect of swelling on KG5
800
Percentage Swelling
700
600
DW
500
pH2.2
400
pH7.4
300
200
100
0
0
2
4
6
8
10
Time (Hours)
Figure 9. Effect of swelling on KG6
products in Nigeria, structure-property relationships and
toxicological studies may be needed.
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