International Journal of Biological Macromolecules 53 (2013) 114– 121
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International Journal of Biological Macromolecules
jo u rn al hom epa ge: www.elsev ier .com/ locate / i jb iomac
valuation of carboxymethyl gellan gum as a mucoadhesive polymer
unish Ahuja ∗, Seema Singh, Ashok Kumarrug Delivery Research Laboratory, Department of Pharmaceutical Sciences, Guru Jambheshwar University of Science and Technology, Hisar 125 001, India
r t i c l e i n f o
rticle history:eceived 18 August 2012eceived in revised form 22 October 2012ccepted 28 October 2012vailable online 21 November 2012
a b s t r a c t
The study was conducted to evaluate carboxymethyl gellan gum as bioadhesive polymer for drug deliveryapplications. Gellan gum was carboxymethylated by reacting it with monochloroacetic acid. Degree ofcarboxymethyl substitution was found to be 1.18. Further, carboxymethylation of gellan gum was foundto increase its degree of crystallinity, surface roughness and diminish the cation-induced gelation. Oncomparative evaluation carboxymethyl gellan gum showed 2.71-fold higher mucoadhesive strength than
eywords:arboxymethyl gellanucoadhesion
ytotoxicityET-CAM
gellan gum. Evaluation of ex vivo ocular tolerance using chorioallantoic membrane of hen’s egg andcytotoxicity screening on Vero cells using resazurin assay revealed that caroboxymethyl gellan gum isnon-irritant and biocompatible. Ionotiropically gelled beads of carboxymethyl gellan gum formulatedusing metformin as the model drug and calcium chloride as the cross-linking agent showed ex vivobioadhesion of 100% over 24 h. Further, it was observed that carboxymethyl gellan gum beads releasedmetformin at a rate faster than gellan gum.
. Introduction
Natural polymers find extensive applications in food andharmaceutical industry because of their easy availability, bio-ompatibility, biodegradability and cost effectiveness. To improveheir functional properties a number of physical modifica-ion approaches such as microfluidization [1], extrusion [2],reeze–thaw cycling [3] and chemical modification approachesuch as graft co-polymerization [4,5], oxidation [6], thiolation7], and carboxymethylation [8], have been employed. Amonghe various chemical modification approaches, carboxymethyla-ion is widely used because of its ease of processing, lower costnd versatility. Carboxymethylation of polysaccharides have ear-ier been done to improve their aqueous solubility and gellingehaviour.
Gellan gum (GG) is an anionic exopolysaccharide secreted byhe microorganism, Pseudomonas elodea. It is a linear polysaccha-ide comprising of repeating tetrasaccharide unit of glucuronic acid,hamnose and glucose residues in a molar ratio of 1:1:2. It possesseshe characteristic property of undergoing ionic gelation in the pres-nce of mono- and divalent-cations [9]. It has been employed inharmaceutical applications as in situ gelling agent in ophthalmicormulations [10] and as a sustained release matrix in bead for-
ulation [11]. Gellan gum has earlier been chemically modifiedy thiolation [12], carbamoylation [13] and carboxymethylation14]. Carboxymethylation of gellan gum was reported to improve
its aqueous solubility and gelling behaviour. It was observed thatcarboxymethylated gellan gum does not gel at 0 ◦C even at the con-centration of 10% (w/v). However, there are no literature reports onfurther use of carboxymethyl gellan gum (CMGG) in pharmaceuti-cal applications. Recently it was reported that carboxymethylationimproves the bioadhesive properties of natural polymers [8].
Thus considering the same, the present study was designedwith the objective of evaluating CMGG as a mucoadhesive poly-mer for pharmaceutical applications. CMGG was synthesized andcharacterized by Fourier transform infrared spectroscopy (FT-IR),differential scanning calorimetry (DSC), X-ray diffraction (XRD) andscanning electron microscopy (SEM) studies. Further, the effect ofcalcium ions on gelling behaviour of CMGG was studied. Mucoad-hesive potential of CMGG was evaluated by texture profile analysis.CMGG was comparatively evaluated with GG for ex vivo ocular tol-erance by Hen’s egg test-chorioallantoic membrane (HET-CAM) andfor cytotoxicity by resazurin assay. The mucoadhesive applicationsof CMGG were explored by formulating ionotropically gelled beadsemploying metformin as a model drug.
2. Materials and methods
2.1. Materials
Gellan gum (Gelrite®, CP Kelcogel, UK) and metformin sam-ples were gifted by Burzin Leons Argenturon (Mumbai, India)
and GMH Laboratories Pvt. Ltd. (Baddi, India), respectively.Monochloroacetic acid was procured from Hi-Media Lab. Pvt. Ltd.(Mumbai, India). Sodium hydroxide, methanol and glacial aceticacid were obtained from Sisco Research Laboratory (Mumbai,
ndia). All other chemicals used were of analytical grade. Freshlyxcised chicken ileum was obtained from local slaughter houseHisar, India).
.2. Synthesis of carboxymethyl gellan gum (CMGG)
CMGG was synthesized from gellan gum as per the syntheticrocedure reported by Miyamoto et al. [14]. Briefly, an aqueousispersion of GG (1.25%, w/v) in ice cold sodium hydroxide (45%,/w) was prepared by stirring for 30 min. To this 25 mL of aqueous
olution of monochloroacetic acid (45%, w/v) was added with con-tant stirring. The reaction mixture was then heated to 70 ◦C underonstant stirring for 30 min, cooled and suspended into (80%, v/v)ethanol. Precipitates of CMGG so formed were filtered and neu-
ralized with glacial acetic acid, followed by washing with 3 × 60 mLortions of methanol (80%, v/v), filtration and drying in an oven at0 ◦C.
.3. Characterization of CMGG
.3.1. Fourier transform infra-red spectroscopy (FT-IR)GG and CMGG samples were subjected to FT-IR spectroscopy
n a Fourier-transform infrared spectrophotometer (IR Affinity-1,himadzu, Japan) in range of 4500–400 cm−1 as KBr pellets.
.3.2. Differential scanning calorimetry (DSC)DSC thermograms of GG and CMGG samples were recorded
sing a differential scanning calorimeter (Q10 V9.0 Build 275, TAystems, USA). About 7–8 mg of sample were crimped in a standardluminium pan and heated in a temperature range of 40–250 ◦C at
heating rate of 10 ◦C per min with nitrogen purge of 50 mL/min.
.3.3. X-ray diffractionPowder X-ray diffraction pattern of GG and CMGG were
ecorded employing X-ray diffractometer (Table top XRD, Miniflex, Rigaku, Japan). The sample powders were scanned from 0◦ to0◦ diffraction angle (2�) range under the following measurementonditions: source, nickel filtered Cu-K� radiation; voltage 30 kV;urrent 15 mA; scan speed 0.05 min−1; division slit 1.25◦; receivinglit 0.3 mm.
.3.4. Scanning electron microscopy (SEM)Scanning electron micrographs of GG and CMGG samples were
aken using SEM (JEOL, JSM-6100). These were coated with goldnd mounted in a sample holder. The photomicrographs of samplesere taken at an accelerating voltage at 5 kV at different magnifi-
ations.
.3.5. Determination of degree of substitutionThe degree of substitution was determined by classical acid-
ash method [15]. In brief, freshly precipitated CMGG (1.5 g) wasispersed in hydrochloric acid reagent (20 mL) for 3–4 h, followedy filtration and washing with 70% methanol to remove the acidollowed by drying to constant weight in an oven at 70 ◦C.
The dried CMGG, so obtained, was well dispersed in 70%ethanol followed by addition of excess of sodium hydroxide
0.5 N) with stirring for 3 h to dissolve the sample completely. Thexcess of sodium hydroxide was back titrated with hydrochloriccid (0.5 N) using phenolphthalein as an indicator. The degree ofarboxymethyl substitution (DS) on GG was calculated using theollowing equation:
S = 0.162A
1 − 0.058A(1)
here A is the milliequivalents of sodium hydroxide required per of the CMGG sample.
ical Macromolecules 53 (2013) 114– 121 115
2.3.6. Effect of cations on gelling behaviourThe effect of cation concentration on gelling behaviour of GG and
CMGG was investigated by plotting partial ternary phase diagram.Aqueous solutions of GG (0.2–2.0%, w/v) and CMGG (0.5–3.0%, w/v)in sodium hydroxide (1%, w/v) were prepared and to them appro-priate amount of CaCl2 solution (0.2–2.0%, w/v) for GG and (1–3.5%,w/v) for CMGG was added and left overnight to equilibrate. Solu-tions were assessed visually for their appearance and flow by tiltingthe test tubes to an angle of 90◦, and were categorized as solutions,precipitate, viscous solutions or gels [16].
2.4. Evaluation of mucoadhesive potential of CMGG
Mucoadhesive potential of CMGG was assessed and compara-tively evaluated with GG by determining the force of detachment oftheir polymer compacts with the mucin-coated model membraneusing texture analyzer. Polymer compacts were prepared by com-pressing 200 mg of polymers in IR hydraulic press (KP 795, KimayaEngineers, Thane, India) using 13 mm die at a pressure of 5 ton for1 min. The mucoadhesive strength was measured in texture ana-lyzer (TAX2, Stable Microsystem, UK), equipped with 5 kg load cell.Polymer compacts were attached to the upper probe, while themodel membrane comprising of a cellophane membrane hydratedwith mucin dispersion (0.3%, w/v) was attached to the lower probe.The upper probe was lowered at a rate of 0.1 mm/s until it contactsthe model membrane followed by application of constant force of0.25 N for 300 s. The upper probe was then withdrawn at a rate of0.1 mm/s and the force required to detach the polymer compactfrom the model membrane was taken as the indicator of mucoad-hesive performance.
2.5. HET-CAM study
Ex vivo ocular tolerance of gellan gum with CMGG and controlsolutions of irritant (NaOH) and non-irritant (NaCl) was assessedemploying hen’s egg test on chorioallantoic membrane (HET-CAM)assay [17]. Ten-day old fertilized hen’s eggs were candled withan illuminating lamp and eggs with an air sac and live embryowere used for further testing. Egg shells were then opened andcarefully removed the membrane without injuring any blood ves-sel using tapered forceps. Eggs which got damaged were rejected.GG and CMGG aliquots of 0.5 mL were applied over CAM in tripli-cates and observed for next 5 min for the signs of irritation such ashaemorrhage, vasoconstriction and coagulation [18]. The time ofappearance of irritation was recorded and potential irritation (PI)score were calculated using the formula:
PI = (301 − h) × 5300
+ (301 − �) × 7300
+ (301 − c) × 9300
(2)
where h = appearance time in seconds of haemorrhage,� = appearance time in seconds of vasoconstriction, c = appearancetime in seconds of coagulation [17]. On the basis of PI val-ues, irritation was recorded as 0–0.9, non irritant; 1–4.9, slightirritation; 5–8.9, moderate irritation; 9–21, severe irritation.
2.6. Cytotoxicity screening
CMGG was screened comparatively for cytotoxicity with GGemploying resazurin assay method. The resazurin assay is basedon measuring the metabolic activity of living cells by determiningthe concentration of resorufin. Resorufin is a pink fluorescentcompound produced by reduction of resazurin (7-hydroxy-3H-
phenoxazin-3-one 10-oxide) by viable cells. The Vero cells wereseeded in 96 well plate in a density of 105 cells in Dulbecco’sModified Eagle’s Medium (DMEM) containing 5% Foetal BovineSerum (FBS) and incubated for 24 h at 37 ◦C in 5% CO2 humidified
1 Biological Macromolecules 53 (2013) 114– 121
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ncubator. After 24 h, the cells were viewed under microscopeor proliferation. The cells which proliferated, were exposed tohe samples of 50 �L of gellan gum solution and CMGG solution100 �g/mL) and incubated in 5% CO2 incubator for another 24 ht 37 ◦C. An aliquot of 20 �L of resazurin (1 mg/mL in DMEM)as then added to each well followed by incubation in 5% CO2umidified incubator for 4 h at 37 ◦C. After 4 h, the plates werenalyzed in ELISA spectrophotometer at 573 nm [19]. Cytotoxicityas calculated using the formula:
cytotoxicity = Absu − Abst
Absu× 100 (3)
here Absu is the absorbance of cells not treated with any polymer,bst is the absorbance of cells treated with GG or CMGG.
.7. Mucoadhesive applications
.7.1. Preparation of CMGG and GG beadsMucoadhesive application of CMGG were explored by prepar-
ng ionotropically gelled beads using metformin as the model drugnd CaCl2 as a cross-linking agent. In brief, an aqueous dispersionf CMGG (5% (w/v) in 1% sodium hydroxide solution) or GG (1%,/v) containing metformin (25% (w/w) of polymer) was extruded
hrough #18G needle into aqueous solution of Cacl2 (20%, w/v)t room temperature. The gelled beads were allowed to hardenor 5 min, followed by washing with distilled water and filtration.eads so obtained were freezed at −80 ◦C for 4 h and further dried
n laboratory model freeze dryer (Alpha 2-4 LD Plus, Martin Christ,ermany) for 24 h at −90 ◦C and 0.0010 mbar.
.7.2. Evaluation of CMGG beadsMetformin loaded CMGG and GG beads were characterized for
rug entrapment efficiency, ex vivo bioadhesion and in vitro releaseehaviour.
.7.3. Entrapment efficiencyIt is the percentage of actual amount of drug encapsulated in the
eads, relative to initial amount of loaded drug
ntrapment efficiency (%) = actual drug loadingtheoretical drug loading
× 100 (4)
he theoretical drug loading was calculated by assuming thatntire drug gets encapsulated in beads. For determining actual drugoading, beads equivalent to 10 mg of drug were taken, groundedn mortar pestle and sonicated for 30 min in 100 mL of phos-hate buffer (pH 6.8), and filtered through 0.45 �m syringe filter.he contents of metformin in the sample were analyzed spec-rophotometrically in UV–vis spectrophotometer by measuring thebsorbance at 233 nm.
.7.4. In vitro drug releaseThe in vitro release behaviour of metformin from CMGG beads
as comparatively evaluated with GG beads using USP type II disso-ution apparatus (TDT-08L, Electrolab, India). Dissolution medium
as 250 mL of phosphate buffer (pH 6.8), maintained at 37 ± 0.5 ◦Cnd rotated at a speed of 50 rpm. Accurately weighed beads equiv-lent to 25 mg of metformin were enclosed in the muslin clothhich was tied to the paddle [20]. Aliquot of 5 mL sample was with-rawn. The contents of metformin in samples were determined byeasuring absorbance at 233 nm in UV–vis spectrophotometer.
.7.5. Ex vivo bioadhesion
Bioadhesive properties of CMGG beads were comparatively
valuated with GG beads by conducting ex vivo bioadhesion studymploying wash-off test method [21]. A freshly excised chickenntestine was procured from a local butcher house (Hisar, India)
Fig. 1. Fourier transform infrared spectra of GG and CMGG.
within an hour of slaughter and kept in a cold isotonic saline (4 ◦C)and cleaned by washing. The intestinal tissue was cut-open and tis-sue was pasted on glass slide using cyanoacrylate glue with mucosalsurface facing outside. About 100 beads of GG and CMGG wereadhered to intestinal mucosal tissue by applying light force withfingertip for 30 s. The glass slide was hung on to arm of USP tabletdisintegrating machine which was suspended in 250 mL of phos-phate buffer (pH 6.8) at 37 ± 0.5 ◦C and tissue specimen was givenslow, regular up and down movement by operating the USP tabletdisintegrating test machine. The number of beads adhering to tissuewas counted at regular intervals up to 24 h.
3. Results and discussion
Carboxymethylation of polysaccharides is carried out byWilliam synthesis, in which the polysaccharide alkoxide is reactedwith monocholoroacetic acid and the primary and secondaryalcohol groups are substituted by carboxymethyl group [22]. Syn-thesized CMGG was characterized by FT-IR, DSC, XRD, and SEMstudies.
Fig. 1 shows the FT-IR spectra of GG and CMGG in the frequencyrange of 4000–400 cm−1. The spectra of GG shows a broad absorp-tion band comprising of a peak due to free OH group of aliphaticalcohol at 3508 cm−1, and contributions due to bonded OH groupsof carboxylic acid at 3313 cm−1 and 3248 cm−1. A shoulder at2904 cm−1 can be attributed to C H stretch of alkane. Further, thespectra shows peaks at 1608 cm−1 and 1402 cm−1 which can beascribed to C O stretching of carboxylate ion. A band at 1041 cm−1
can be attributed to C O stretch of carboxylic acid. The spectra ofCMGG shows a broad band from 3300 cm−1 to 3100 cm−1 due tooverlapping contributions of free and bonded OH groups of car-boxylic acid. It also shows two shoulder peaks at 2980 cm−1 and2951 cm−1 due to C H stretch of alkane. The peaks due to C Ostretch of carboxylate ion appear at 1612 cm−1 while the C Ostretch of carboxylic acid appears at 1055 cm−1. The increase in
intensity and numbers of peaks due to OH stretch of carboxylicacid confirms the modification of gellan gum.
Fig. 2 exhibits the DSC thermograms of GG and CMGG. Ther-mal curve of GG shows a broad endotherm at 96.68 ◦C with
M. Ahuja et al. / International Journal of Biological Macromolecules 53 (2013) 114– 121 117
Fig. 2. Differential scanning calorimetric of GG and CMGG.
Fig. 3. Powder X-ray diffraction of CMGG and GG.
118 M. Ahuja et al. / International Journal of Biological Macromolecules 53 (2013) 114– 121
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Fig. 4. Scanning electron micrographs showing the sha
eat flow of 275 J/g followed by two exotherms at 253.42 ◦Cnd 260.31 ◦C with heat flow of 21.26 J/g and 60.78 J/g, respec-ively. The DSC curve of CMGG shows a broad endotherm at34.22 ◦C with heat flow of 269.2 J/g followed by an exotherm at
26.12 ◦C with heat flow of 30.63 J/g. The shift in the endother-ic peak, disappearance of one exotherm and variation in the
eat flow indicate that modification of GG has taken place onarboxymethylation.
(a) CMGG, (b) GG, and surface of (c) CMGG, and (d) GG.
Fig. 3 displays the X-ray diffraction pattern of GG and CMGG. Thediffractogram of GG is typical of amorphous materials with no sharppeaks while diffractogram of CMGG shows the typical characteris-tic peaks appearing at 23.600◦, 25.120◦, 26.740◦, 27.420◦, 27.760◦,
30.260◦, 31.780◦, 33.140◦, 45.50◦, 56.480◦, 75.280◦ (2� scale) whichindicates the increase in crystallinity of GG on carboxymethylation.
The scanning electron micrographs (Fig. 4(a)–(d)) show theshape and surface morphology of GG and CMGG particles. It can
+ ion conc. of gelling behaviour of CMGG and GG.
M. Ahuja et al. / International Journal of Biolog
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Fig. 6. Tensile test profiles of GG and CMGG polymer compacts.
e observed from the micrographs that GG and CMGG particlesre polyhedral in shape but CMGG particles are rougher with theirurface covered with needle shaped fibres.
The sample of CMGG was found to have degree of car-oxymethyl substitution of 1.18 as determined by classicalcid-wash method.
f Ca2+ ions on gelling behaviour of GG and CMGG and indicatehat GG at concentration less than 0.2% (w/v) formed viscous solu-ion in presence of Ca2+. But at concentration greater than 0.2%w/v), it gelled in the presence of Ca2+. While in case of CMGG, it
Fig. 7. Cytotoxic effects of GG an
ical Macromolecules 53 (2013) 114– 121 119
was observed that it remains in solution in concentration rangeof (0.5–2.25%, w/v) in the presence of Ca2+ concentration <1.25%(w/v). But on increasing the Ca2+ concentration >1.25% (w/v), itbecomes viscous. Further, it can be inferred from ternary phasediagram, that increasing the CMGG concentration >2.25% (w/v) inthe presence of Ca2+ results in gel formation. In addition, it wasobserved that CMGG in the concentration range of (0.75–1%, w/v),in the presence of Ca2+ concentration of (2.5–3.25%, w/v) resultsin the formation of precipitates. During earlier studies with gellangum, it was reported that there is a critical level of Ca2+ concen-tration below which it helps in the formation of gel but abovethis critical concentration, it occupies all the anionic sites on gel-lan chain preventing the formation of linkages between doublehelices of gellan gum decreasing the gel strength [23]. Similarmechanism explains the precipitate formation of CMGG that Ca2+
above the concentration of 2.5% (w/v) prevents the linkage for-mation, thus reducing the gel strength and leads to precipitateformation.
Fig. 6 compares the tensile strength profiles conducted usingGG and CMGG polymer compacts. The force required to detach theCMGG and GG polymer compacts from the mucin coated modelmembrane was found to be 57.9 ± 17.9 g and 21.31 ± 8.68 g, respec-tively. Thus, CMGG polymer compacts showed 2.71-fold greateradhesion than the GG. Improvement in mucoadhesive characteris-tic of GG on carboxymethylation led us to explore it for formulatingmucoadhesive dosage form.
Gellan gum has been evaluated as an in situ gelling polymerfor ocular delivery of indomethacin, timolol maleate, gatifloxacinetc. [16]. Thus to check whether carboxymethylation affects theirritation potential of gellan gum, CMGG was comparatively eval-uated with gellan gum for ex vivo ocular tolerance employingHET-CAM assay. HET-CAM method can be used as an alternative toDraize rabbit eye test for evaluating the potential eye irritation offormulated compounds that are to be instilled in eye [18]. It is a sim-ple, rapid and sensitive test and relatively cost effective to Draizerabbit eye test. Chorioallantoic membrane has a structure similar toconjunctiva and thus it is considered an ideal test for checking theocular irritation of products. In the present study, it was observed
that GG and CMGG at 0.1% (w/v) showed no signs of irritation onchorioallantoic membrane up till 5 min on application of products.Results obtained indicate that carboxymethylation does not affectocular irritation potential of GG.
d CMGG on Vero cell lines.
120 M. Ahuja et al. / International Journal of Biological Macromolecules 53 (2013) 114– 121
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surface of bead during the gelation of beads, resulting in burstrelease of the drug. Similarly faster release of metformin fromCMGG beads as compared with GG beads can be attributed to
Fig. 8. Scanning electron micrographs showing sha
In addition to conform and check the biocompatibility of CMGG,hey were also evaluated for cytotoxicity against Vero cell linesmploying resazurin method.
Fig. 7 displays the result of resazurin assay for cytotoxicity. Theesults revealed no significant difference in the effects of GG andMGG on Vero cell lines, with GG and CMGG affording 89.03% and0.32% cell-viability, respectively, after 24 h exposure.
Mucoadhesive applications of CMGG were evaluated by prepar-ng ionotropically gelled beads using metformin as the modelrug. Metformin, a biguanide hypoglycemic agent, was selected ashe model drug because it shows dose dependent, saturable drugbsorption from the upper part of intestine. To improve its oralbsorption, bioadhesive formulations have been used earlier [24].arboxymethylation of GG improves its solubility and reduces itsiscosity. Further, it was observed during our studies that CMGGels at a higher concentration than that required for GG. As a resulteads of GG and CMGG were formulated using a concentration of% (w/v) and 5% (w/v), respectively.
The entrapment efficiency of metformin from GG and CMGGeads were found to be 16.44% and 22.58%, respectively. The exivo bioadhesion studies conducted using chicken ileum by washff method revealed no difference between GG and CMGG beads,ith both the beads showing 100% bioadhesion during the 24 heriod of the study.
The scanning electron micrographs (Fig. 8(a)–(d)) of GG andMGG bead show that beads are ovoid shape with rough and porousurface.
Fig. 9 compares the in vitro release profile of metformin from GGnd CMGG beads. It can be observed from the release profile thatMGG beads showed an initial burst release of the drug, with 28%f the drug getting released in first 30 min.
surface of CMGG (a and b) and GG (c and d) beads.
Further, CMGG beads released the drug at a faster rate than GGbeads. The release of the drug depends upon the diffusion throughviscous gel matrix. Carboxymethylation of GG reduces its viscosity.The burst release and the faster release of metformin from CMGGbeads can be explained by decreased viscosity of CMGG. Due todecrease in viscosity, a greater amount of drug migrates to the
Fig. 9. In vitro release profile of metformin from ionotropically gelled GG and CMGGbeads.
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he lesser viscosity of CMGG matrix. However, by optimizing theoncentration of drug, polymer and the cross-linker, a desiredelease profile for the desired period can be achieved.
. Conclusion
GG was modified by carboxymethylation, which was con-rmed by FT-IR spectroscopy. Characterization of CMGG revealed
ncrease in crystallinity, surface roughness, and decrease in cation-romoted gelation and improvement in mucoadhesive properties.urther, carboxymethylation did not affect the ocular irritationotential and the biocompatibility of GG. Mucoadhesive applica-ions of CMGG were explored by formulating ionotropically gelledeads of metformin, which requires further optimization of formu-
ation and processing variables. It can be concluded on the basisf the present study that CMGG is a promising bioadhesive, andiocompatible polymer, which should be explored for further appli-ations in pharmaceutical technology.
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