Journal of Biomaterials and Nanobiotechnology, 2011, 2, 85-90
doi:10.4236/jbnb.2011.21011 Published Online January 2011 (http://www.SciRP.org/journal/jbnb)
Polymeric Biomaterial Based Hydrogels for
Biomedical Applications
Nabanita Saha,* Aamarjargal Saarai, Niladri Roy, Takeshi Kitano, Petr Saha
Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, Zlin, Czech Republic.
Received October 2nd, 2010; revised December 15th, 2010; accepted December 20th, 2010.
ABSTRACT
This paper focuses on the sign ificant properties of hy drogels prepared with polymeric biomaterials: so lely biopolymers
(gelatin (G) and sodium alginate (SA) as base polymer) or in combination with synthetic and bio polymers (polyvi-
nylpyrrolidone (PVP) and carboxymethylcellulose (CMC)) for biomedical application. Four kinds of hydrogels: G/SA,
G/SA/SB (without and with seabuckthron oil (SB)) and PVP/CMC, PVP/CMC/BA (without and with boric acid (BA))
which are different from each other concerning shape, size, color, texture and properties point of view were achieved.
G/SA and G/SA/SB hydrogels vary from pale yellow to orange and a little rubber like having 42-48 % moisture. On the
other hand, PVP/CMC and PVP/CMC/BA hydrogels are transparent and soft gel like containing about 90-95% mois-
ture. Both G/SA and PVP/CMC hydrogels show similar trend of viscoelastic behaviour within whole range of measured
angular frequency (0.1 – 100 rad.s-1). However, the presence of BA in PVP/CMC/BA, increases the storage modulus,
loss modulus and complex viscosity of hydrogel, and the presence of SB in G/SA/SB demonstrates the decrease all of
these values. G/SA based hydrogel possesses natural antimicrobial property whereas PVP/CMC based hydrogel needs
to incorporate antimicrobial agent to comprise antimicrobial property within the hydrogel. G/SA hydrogels show water
absorption capacity until 90 min whereas PVP/CMC hydrogels are able to absorb water steadily till 240 min. Finally, it
can be mentioned that all four hydrogels: G/SA, G/SA/SB, PVP/CMC, PVP/CMC/BA which meet the basic requirements
of hydrogel dressings, could be recommended as dressing materials for healing of burn or cut wound as well as a tool
for transdermal drug de livery.
Keywords: Antimicrobial Property, Hydrogel, Polymeric Biomaterial, Transdermal Drug Delivery, Wound Dressings.
1. Introduction
A biomaterial is a synthetic material used to replace part of
a living system or to function in intimate contact with
living tissue [1]. The word “biomaterial” is generally used
to recognize materials for biomedical applications. Bio-
materials save lives, relieve suffering and improve the
quality of life for a large number of patients every year.
According to the use of materials in the body, biomaterials
are classified into four groups: polymers, metals, ceramics
and composites [2,3].
Polymeric biomaterials (PB) are polysaccharides (starch,
cellulose, chitin, alginate, hyaluronate etc.) or proteins
(collagens, gelatins, caseins, albumins) and / or synthetic
and biodegradable polymers (Polyvinyl alcohol (PVA),
Polyvinylpyrrolidone (PVP), Polyetheleneglycol (PEG),
Polylactic acid (PLA), Polyhydroxy acid (PHA) etc.).
Currently, applications of polymeric biomaterials are
promising for drug delivery, tissue engineering, bio-
medical sensing, skin grafting, medical adhesives and
textiles etc. It also covers targeted drug delivery to the
nervous system, gastrointestinal tract, and kidneys etc. PB
also includes the modern textile-based biomaterials for
surgical applications; novel techniques in biomimetic
polymer preparation; contemporary uses for polymers in
dental and maxillofacial surgery; and many more [4].
From a practical perspective, medical applications of
polymers fall into three broad categories: (i) extracorpo-
real uses (catheters, tubing, and fluid lines; dialysis
membranes/artificial kidney; ocular devices; wound
dressings and artificial skin), (ii) permanently implanted
devices (sensory devices; cardiovascular devices; ortho-
pedic devices; dental devices), and (iii) temporary im-
plants (degradable sutures; implantable drug delivery
systems; polymeric scaffolds for cell or tissue transplants;
temporary vascular grafts and arterial stents ; temporary
small bone fixation devices, transdermal drug delivery)
[5,6].

Polymeric Biomaterial Based Hydrogels for Biomedical Applications 86
Among all these prospective applications of PB in
biomedical applications, concentration has given for the
development of polymeric hydrogels as wound dressing
cum wound healing material considering its application
for extracorporeal purposes. Hydrogels are super absor-
bent polymeric materials which have significant roles in
health care especially for wound treatment / protection.
This might be due to their hydrophillicity, biocompatibil-
ity, non-toxicity, and biodegradability. Hydrogel pos-
sesses many remarkable properties such as immediate
pain control effect, easy replacement, transparency, bar-
rier against bacteria, good adhesion, easy handling, oxy-
gen permeability, control of drug dosage, absorption, and
prevention of loss of body fluids [7-14]. From healthcare
points of view, hydrogel dressings have become a very
interesting field of research for the development of a user
friendly medical device for mankind. Numerous research
studies prove that a moist wound environment is best for
wounds to heal [15-19]. Two kinds of hydrogel based on
PB have been developed, investigated in our laboratory
and reported elsewhere [8,9,12,13]. The properties of two
types of hydrogels (the one is prepared solely with bio-
polymers and the other is prepared in combination with
biopolymer and synthetic polymer) were compared and
mentioned in this paper.
2. Experimental
Polymeric (biopolymer) biomaterial based hydrogels: the
hydrogels were prepared with biopolymers like gelatin (G)
and sodium alginate (SA) and without and with 0.5 ml
seabuckthorn oil (SB), as a skin care plus wound healing
agent. Accordingly, the new hydrogels are named as
G/SA and G/SA/SB hydrogels. These hydrogels were
prepared by applying physical stimulation technique;
under constant stirring at 80 oC for 5 min using ingredients
(gelatin 5; sodium alginate 5; PEG 2; glycerin 2; NaCl 0.2
gm / 20 ml water)[8,9]. The semi solid polymeric mass
(pseudo gel) was then placed in a grooved (25 mm di-
ameter and 2 mm thickness) acrylic plate and allowed it to
become solid at room temperature.
Polymeric (synthetic and biopolymer) biomaterial
based hydrogels: The other types of hydrogels were pre-
pared with polyvinylpyrrolidone (PVP, synthetic polymer)
and carboxymethylcellulose (CMC, biopolymer) incur-
poration of without and with 3% boric acid (BA), as an
antimicrobial agent. Accordingly, the new hydrogels are
named as PVP/CMC and PVP/CMC/BA hydrogels. These
hydrogels were prepared under controlled pressure, moist
heat and time (i.e. 15 lb, 120oC and 15 min) using ingre-
dients (PVP/CMC 2:8; PEG 1; glycerin 1; agar 1 gm / 100
ml water).The liquid polymeric mass (20 ml) was then
transmitted in a Petri plate (80 mm diameter) and allowed
to be cooled at room temperature to develop hydrogel
(pseudo gel) [12,13,20,21].
The essential and significant properties [physical
(moisture content and morphology), viscoelastic, antim-
icrobial and swelling] of hydrogels are characterized and
described below:
Moisture content of the hydrogels was measured gra-
vimetrically by using the following equation (1).




% =100
nwdw
MWWW



(1)
Where, Mn = moisture content (%) of material n, WW =
wet weight of the sample, and Wd = weight of the sample
after drying at room temperature till they assumed con-
stant weight [22]. Three replicates were taken and the
average value of moisture content was determined.
The physical appearance (diameter and thickness) of
hydrogels were measured using vernier scale and the
interior morphologies were evaluated by scanning elec-
tron microscopy (SEM) analysis (VEGA II LMU
(TESCAN)) operating in the high vacuum / secondary
electron imaging mode at an accelerating voltage of 5-20
kV). The freeze dried samples of before dry samples of
hydrogels were analyzed [12]. The hydrogels were fro-
zen under -81ºC for 72 hours and then lyophilized (AL-
PHA 1-4 LSC, Labicom s.r.o, Czech Republic) for 24
hours. Thereafter, the samples were sputter coated with a
thin layer of palladium / gold alloy to improve the sur-
face conductivity and tilted 30° for better observation.
The surface views as well as the cross-sectional views of
the hydrogels were taken at magnification of 100 x – 10
kx.
The dynamic viscoelastic behavior of hydrogel samples
were investigated by using a parallel plate rheometer
(ARES; Rheometrics Scientific, USA) testing machine
with an “RSI Orchestrator” software package. A 25 mm
diameter parallel plate measuring geometry, with a gap of
about 2-3 mm was used for the measurements under small
strain amplitude (1%) to maintain the measurements
within the linear viscoelastic region (LVER). Dynamic
frequency sweep tests were carried out at 28oC to observe
the storage modulus (G’) and loss modulus (G’’) as a
function of a wide range of angular frequencies (ω:
0.1-100 rad/s) [12,13]. In each case, three samples from
the same hydrogel samples were measured.
The antimicrobial properties of hydrogels: G/SA,
G/SA/SB and PVP/CMC, PVP/CMC/BA were investi-
gated by agar diffusion method [13,23-25] where their
antibacterial efficiency were examined on the basis of the
dimension of inhibition zone generated in presence of
Staphylococcus sp (bacteria) and Candida sp (fungus).
The antimicrobial assay was conducted using sterile Nu-
trient Agar (2%) medium for bacterial strain and Czapex
Dox Agar (2%) medium for fungal strain respectively.
The testing plates were then incubated in a temperature

Polymeric Biomaterial Based Hydrogels for Biomedical Applications 87
controlled incubator at 37°C for Staphylococcus sp (bac-
teria) and at 30°C for Candi da sp (fungus) to observe the
effectivity of the hydrogels to inhibit the growth of
microbes respectively.
The degree of swelling can be described as water ab-
sorptivity of the hydrogel. In case of G/SA and G/SA/SB,
whole dry hydrogel samples were considered and for
PVP/CMC and PVP/CMC/BA, a small piece (1 cm2)
from the dry films were weighed and immersed in dis-
tilled water at room temperature until reached to equilib-
rium state. After the specified time intervals, the water on
the swollen gels was wiped off with tissue paper, and the
weight of specimens was determined. The degree of
swelling corresponds to the water absorptivity of the ma-
terial, which is defined by equation 2 where, Ws and Wd
are weights of swollen gel and dried gel, respectively
[12,13, 26-28].



%100
sdd
Absorption WWW  (2)
3. Results and Discussion
Based on PB finally, four kinds of hydrogels i.e. G/SA,
G/SA/SB and PVP/CMC, PVP/CMC/BA were achieved,
which are actually different (shape, size, color, texture and
property) from each other. The images of the above men-
tioned hydrogels are shown in Figure 1 and Figure 2,
respectively.
The G/SA is pale yellow and rubber like during before
dry state and then turned into hard, ivory colored at dry
condition. Similarly, G/SA/SB is orange in color and
rubber like turns into light yellow while dried (Figure 1).
The observable orange color of G/SA/SB hydrogel is
mainly due to the presence of SB oil in hydrogel.
The PVP/CMC and PVP/CMC/BA hydrogels are off
white, transparent and soft gel like, moreover, no noticeable
differences observed between the PB (synthetic and bio-
polymer) hydrogel at before dry state. But, after drying at
Figure 1. Optical images of hydrogels: G/SA (a.i) before dry
(a.ii) dry and G/SA/SB (b.i) befor e dry (b. ii) dry.
Figure 2. Optical images of hydrogels: PVP/CMC (a.i) be-
fore dry (a.ii) dry and PVP/CMC/BA (b.i) before dry (b.ii)
dry.
room temperature, a remarkable difference is observed
among these two hydrogels i.e. presence of BA is visible
on the surface (in the form of white dots) of dry
PVP/CMC/BA hydrogel (Figure 2).
While considering the physical appearance of PB hy-
drogels, it can be noticed that the G/SA and G/SA/SB
decrease both in diameter and thickness after drying at
room temperature. In each case of biopolymer based hy-
drogel the diameter is decreased from 25 mm to 20 mm,
thickness reduces from 2.437 to 1.869 (G/SA) and 2.245
to 1.865(G/SA/SB), respectively. Thus, it is assumed that
due to the presence of SB oil, the G/SA/SB contains less
water than G/SA. The moisture content of biopolymer
based hydrogel varies between 42-48 % (Table 1). Con-
cerning the size, the PB (synthetic and biopolymer) hy-
drogel does not show any difference in diameter after
drying at room temperature but they exhibit visible dif-
ferences in thickness as they hold a large quantity of wa-
ter (approximately 90-95 %) as shown in Table 2.
The surface topography and cross-sectional structure
of the freeze dried samples of G/SA, G/SA/SB and
PVP/CMC, PVP/CMC/BA hydrogels were examined by
scanning electronic microscopy (SEM) and depicted in
Figures 3 and 4, respectively. It can be seen that highly
porous, flake like structure has been developed within
G/SA and G/SA/SB hydrogels (Figure 3) without using
Table 1. Physical properties of polymeric (biopolymer)
biomaterial based hydrogels.
Diameter (mm) Thickness (mm)
Sample
index Before
dry
DryBefore
dry
Dry
Moisture
content
(%)
G/SA 25 20 2.437 1.869 48.4
G/SA/SB 25 20 2.245 1.865 41.9

Polymeric Biomaterial Based Hydrogels for Biomedical Applications 88
Table 2. Physical properties of polymeric (bio and synthetic)
biomaterial based hydr ogel.
Diameter mm) Thickness (mm)
Sample
index Before
dry Dry Before dry Dry
Moisture
content
(%)
PVP/CMC 70 70 2.20 0.120 94.55
PVP/CMC/BA 70 70 2.25 0.412 90.60
Figure 3. SEM images of hydrogels: G/SA (a.i) surface (a.ii)
cross section and G/SA/SB (b.i) surface (b.ii) cross section.
Figure 4. SEM images of hydrogels: PVP/CMC (a.i) surface
(a.ii) cross section and PVP/CMC/BA (b.i) surface (b.ii)
cross section.
any crosslinking agents. Only the influence of physical
agents (temperature and stirring) stimulates to form the
pseudo gel of G and SA. Presence of SB oil does not
persuade much for enhancement of crosslinking network
within the PB (biopolymer) based hydrogel. In addition,
when comparing the internal structure of PVP/CMC and
PVP/CMC/BA hydrogels, PVP/CMC/BA exhibits more
dense, sponge like crosslinking structure. The incorpora-
tion of BA in PVP/CMC hydrogel increased the entan-
glement of the hydrogel network (Figure 4).
The viscoelastic behaviour of hydrogel is essential to
study on application point of view as surface of the hu-
man body is uneven. It can be seen from the Figures 5
and 6 that both the hydrogels (G/SA and PVP/CMC)
show normal gel properties i.e. storage modulus (G’) is
Figure 5. The viscoelastic behavior of hydrogels: G/SA and
G/SA/SB.
higher than the loss modulus (G”). It can also be seen
that both G/SA and PVP/CMC hydrogels show similar
trend of viscoelastic behaviour within whole range of
angular frequency (0.1-100 rad.s-1) but their starting val-
ues (storage or elastic modulus, loss or viscous modulus
and complex viscosity) are different. All these values are
little reduced in G/SA/SB hydrogel due to the presence
of seabuckthorn oil (SB) whereas in case of
PVP/CMC/BA hydrogel it shows just an opposite be-
haviour. Presence of boric acid (BA) increased storage
modulus, loss modulus even complex viscosity of hy-
drogel. It proves that BA helps to improve the cross
linking net work between PVP and CMC. This effect of
BA (the improvement of cross linking net work) is able
to be observed in the SEM image shown in Figures 4b (i)
and (ii).
The efficiency of antimicrobial properties of hydrogel
is necessary to be determined before recommendation of
its application for health care purposes as the presence of
pathogenic microbes like bacteria (Staphylococcus sp)
and fungi (Candida sp) are quite natural on wound infec-
tion, wound burn or fresh wound of skin. It can be seen
from Figure 7 that both G/SA and G/SA/SB exhibit the
antimicrobial effect in presence of both bacteria and fungi
which is natural in origin. This may be due to the presence
of sodium alginate which has antimicrobial property itself.
Seabuckthorn oil (SB) does not play any role on this as-
pect, whereas BA (3%) along with PVP/CMC hydrogel
shows significant influence to achieve antimicrobial
property as shown in Figure 8.
Water or fluid absorption capacity of the hydrogel is
one of the important parameters from wound dressing
point of view. When injury occurs on skin surface usu-
ally blood comes out which contains about 90% of water.
Thus, prior to recommend about hydrogel for biomedical
application it is prudent to work out the water uptake ca-
pacity of hydrogel. It can be seen from Figures 9 and 10

Polymeric Biomaterial Based Hydrogels for Biomedical Applications 89
Figure 6. T he viscoel astic behavior of hydrogels: PVP/CMC
and PVP/CMC/BA.
Figure 7. Images of antimicrobial properties of hydrogels:
G/SA and G/SA/SB (a) Staphylococcus sp. (b) Candida sp.
Figure 8. Images of antimicrobial properties of hydrogels:
PVP/CMC and PVP / CMC/BA (a) Staphylococcus sp. (b)
Candida sp.
that all hydrogels have reasonable water uptake capacity
up to a long duration. G/SA hydrogels can absorb water
until 90 min whereas PVP/CMC hydrogel can absorb
water steadily till 240 min. Further, it is recognized that
the presence of seabuckthorn oil (SB) and boric acid (BA)
for each hydrogel reduces the water uptake quantity. In
the case of SB, the difference of water uptake quantity is
not so significant however in the case of BA, it is very
high.
4. Conclusions
All four kinds of hydrogels (G/SA & G/SA/SB and
PVP/CMC & PVP/CMC/BA) meet the basic requirements
of existing dressing materials usually used for health care.
Figure 9. Swelling behavior of hydrogels: G/SA and
G/SA/SB.
Figure 10. Swelling behavior of hydrogels: PVP/CMC and
PVP/CMC/BA.
Thus, these hydrogels may be possible to use for health
care purpose like: transdermal drug delivery, wound
dressing, etc. It can be suggested that G/SA and G/SA/SB
hydrogels will be pretty good for wound healing cum
wound protection and PVP/CMC and PVP/CMC/BA
hydrogels could be excellent for wound dressing cum
wound healing purposes. Further, it can be pointed out
that these hydrogels could be stored in dry form and can
be used as and when required which is an additional ad-
vantage of PB based hydrogels. Moreover, these hy-
drogels could be recommended for their use as a medical
device for transdermal drug delivery purposes as well.
5. Acknowledgements
The authors are thankful to the Ministry of Education,
Youth and Sports of the Czech Republic (MSM
70088352101) for financial support.
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