Chitosan Hydrogels & Glutaraldehyde-Crosslinked Counterparts (PDF)

Journal of Physical Chemistry & ys ica l Chemist ry Akakuru and Isiuku, J Phys Chem Biophys 2017, 7:3...

Journal of Physical Chemistry & ys ica l Chemist ry Akakuru and Isiuku, J Phys Chem Biophys 2017, 7:3 DOI: 10.4172/2161-0398.1000256 urnal of Ph & Biophysics Biophysics Jo ISSN: 2161-0398 Research Article OMICS International Open Access Chitosan Hydrogels and their Glutaraldehyde-Crosslinked Counterparts as Potential Drug Release and Tissue Engineering Systems - Synthesis, Characterization, Swelling Kinetics and Mechanism Akakuru OU1* and Isiuku BO2 1 Department of Pure and Applied Chemistry, University of Calabar, Nigeria 2 Department of Pure and Industrial Chemistry, Imo State University, Owerri, Nigeria Abstract Snail shells had been utilized to prepare chitosan and hydrogels of the chitosan were also prepared and crosslinked with varying amounts of glutaraldehyde to achieve different crosslink densities between 0.75 and 1.50. The materials were characterized in terms of the dependence of their swellabilities on time and pH. FTIR analysis was also carried out on the hydrogels and the results obtained show a band at 3451 cm-1, attributed to O-H stretching of the chitosan. The crosslinked hydrogels also showed an N-H bending vibration at 1635 cm-1 which has a reduced intensity and has moved to a lower wavenumber when compared to the N-H bending vibration of the uncrosslinked chitosan hydrogels at 1652 cm-1. The swelling studies showed that the extent of swelling of the hydrogels was dependent on the crosslink density (CD), increasing as CD increased. Uncrosslinked chitosan hydrogel had maximum swelling of 162.71% while that for the crosslinked chitosan hydrogels with CD of 0.75, 1.00 and 1.50 were 119.87%, 93.21% and 87.65% respectively. In all cases, their crosslinked counterparts had decreased swellabilities suggesting that, the crosslinked chitosan hydrogels can be used for a more controlled delivery of drugs and as efficient materials for tissue engineering. The chitosan hydrogels showed maximum percent swellability in highly acidic medium (pH2) equally suggesting the potential of these hydrogels as drug release systems in this medium. The swelling of the chitosan hydrogels followed second-order kinetics and their swelling diffusion exponents ranged from 0.142 to 0.155, indicative of a Less Fickian diffusion or transport mode. Keywords: Chitosan; Hydrogels; Swellability; Drug delivery; Tissue pharmaceutical field for a wide range of drug delivery and in tissue engineering engineering. Chitosan is also a linear polysaccharide composed of randomly distributed β-(1-4)-linked D-glucosamine (deacetylated unit) Introduction and N-acetyl-D-glucosamine, which is the acetylated unit. Chitosan has a rich history of being researched for applications in medicine, A hydrogel (also called aquagel) is a three-dimensional agriculture, biology, and horticulture dating back to the 1980s. However, macromolecular network of polymer chains that are hydrophilic, chitosan has certain limitations for use in controlled drug delivery and sometimes found as colloidal gels in which water is the dispersion tissue engineering. These limitations can be overcome by chemical medium. Three-dimensional networks are usually formed by chemical modification. Thus, modified chitosan hydrogels by crosslinking have or physical crosslinking of hydrophilic polymer chains. In chemical gained importance in current research on drug delivery and tissue gels, polymer chains are connected by covalent bonds, but in physical engineering systems. Modifications of chitosan can improve the gels they are held together by noncovalent bonds, such as van der polymers’ inherent properties which include biocompatibility, chemical Waals interactions, ionic interactions, hydrogen bonding, hydrophobic versatility, biodegradability and low toxicity. These modifications can interactions, traces of crystallinity and multiple helices or by molecular be tailored for a specific application. For example, crosslinking entanglements. Different synthetic, natural and modified natural chitosan with crosslinking agents such as glutaraldehyde or sodium polymers, including chitosan, are used to form hydrogels. Hydrogels tripolyphosphate, has proved to be a convenient and effective method of are stable upon swelling in water and are capable of absorbing a large improving the physical and chemical properties of chitosan for practical amount of water, varying from 10% to thousands of times of its own applications. volume. Hydrogels based on natural polymers are currently receiving a great deal of interest, and are notable for controlled delivery of bioactive The wide varieties of applications of chitosan are due not only to its molecules and tissue engineering. The hydrogels of chitosan, like other hydrogels, contain much water. Part of this water is tightly bound to the polymer and the rest is present *Corresponding author: Akakuru OU, Department of Pure and Applied Chemistry, University of Calabar, Nigeria, Tel: +2348068081656; E-mail: as free water. Chitosan-based hydrogels have been reported to [email protected] exhibit good biocompatibility, low degradation and processing ease. The Received September 08, 2017; Accepted September 25, 2017; Published ability of these hydrogels to swell in water and dehydrate depends on its September 30, 2017 composition, biodegradability, and environment. These dependences Citation: Akakuru OU, Isiuku BO (2017) Chitosan Hydrogels and their have been exploited to facilitate a range of applications such as drug Glutaraldehyde-Crosslinked Counterparts as Potential Drug Release and Tissue release. Chitosan has also been defined as the deacetylated derivative Engineering Systems - Synthesis, Characterization, Swelling Kinetics and of chitin which is a water insoluble polymer (N-acetyl-D-glucosamine), Mechanism. J Phys Chem Biophys 7: 256. doi: 10.4172/2161-0398.1000256 found in nature as present in the outer shells of snails, crabs, shrimps, Copyright: © 2017 Akakuru OU, et al. This is an open-access article distributed lobsters, insects, and fungal cell walls. It is a natural, biodegradable, under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the biocompatible, bioadhesive polymer, and is gaining attention in the original author and source are credited. J Phys Chem Biophys, an open access journal ISSN: 2161-0398 Volume 7 Issue 3 1000256 Citation: Akakuru OU, Isiuku BO (2017) Chitosan Hydrogels and their Glutaraldehyde-Crosslinked Counterparts as Potential Drug Release and Tissue Engineering Systems - Synthesis, Characterization, Swelling Kinetics and Mechanism. J Phys Chem Biophys 7: 256. doi: 10.4172/2161- 0398.1000256 Page 2 of 7 excellent biocompatibility, biodegradability, and economic efficiency, experiment, three separate 1.5 g of chitosan were dissolved in 20.0 but also due to its distinct chemical structure with high percentage of mL of 2.0% aqueous acetic acid in three different beakers at room primary amino groups (-NH2) for easy binding to biomolecules such as temperature with continuous stirring for 24 hours to obtain pale yellow DNAs and proteins. viscous chitosan solutions. Few drops of 0.5% tween-80 were again added to the solutions. The solutions were also filtered with the sintered Drug release from chitosan-based solid dosages depends upon glass crucible and 0.1% aqueous glutaraldehyde solution in different the morphology, size, density, and extent of crosslinking of the amounts (1.0 mL, 1.5 mL, and 2.0 mL) were added to the three different particulate system, physico-chemical properties of drug as well as the samples of clear pale-yellow chitosan solutions to obtain solutions polymer characteristics such as whether the polymer is hydrophilic or with different crosslink densities of 1.50, 1.00, and 0.75 respectively. hydrophobic, has gel formation potentials, swelling capacity, muco- The solutions were stirred for 30 minutes at room temperature as or bio-adhesive properties and also depends on the presence of other they became increasingly viscous and with more intense colour. These excepients present in the dosage form. Since chitosan does not solutions were thereafter cast into a petri dishes and dried overnight cause any biological hazard and is inexpensive, it is suitable for use in at room temperature to form the crosslinked chitosan hydrogels. The the preparation of solid dosage forms of commercial drugs and as semi-dried, crosslinked hydrogels were further dried in an oven at 45°C materials for tissue engineering. for 12 hours to completely remove the residual solvent. Experimental Characterization of the hydrogels Materials Structural characterization of the hydrogels by Fourier Transform Glutaraldehyde (pentane-1,5-dial), was supplied by Qualikems Infrared (FTIR) spectral analysis: Infrared transmission spectra of the (India). Sodium hydroxide, acetic acid, tween-80, sodium hypochlorite, hydrogels were studied using Perkin-Elmer FTIR spectrophotometer and concentrated hydrochloric acid were of analytical grades from (model 2000) in KBr discs from 4000 to 400 cm-1. This FTIR study was BDH. carried out to the functional groups in the hydrogels. Preparation of chitosan from snail shells Swellability studies: The swelling ability of the uncrosslinked and crosslinked chitosan hydrogels were measured by determining the African giant land snail shells (Archarchatina marginata) were percentage of swelling (S) using Equation (1). collected from a local market in Mbaitoli Local Government Area of Imo State, Nigeria, washed, sun-dried for two weeks and pulverized. Ws − Wd =S ×100 (1) The ground shells were later sieved with a mesh sieve (425 μm). The Wd sieved snail shell powder (250.0 g) was treated with 3.0 L of 1.2 M where Wd is the mass of dry sample in g and Ws is the mass of swollen NaOH solution for two and half hours at 75°C, with stirring at intervals. sample at time t. Completely dry hydrogel of known mass (Wd) was After the heating process, the solution was allowed to cool, then, the immersed on definite time period in buffer solution and after time t, the excess NaOH solution was removed by decantation, followed by sample was taken out from the solution and quickly wiped with filter washing with deionized water to neutral pH, filtration, and air-drying paper and weighed (Ws). The swellability studies of the test materials of the residue. The recovered sample from the deproteinization process was placed into 2.72 L of 0.7 M HCl solution for 20 minutes. The excess were carried out in water (27°C) at different pH values (2, 4, 6, and 8) HCl solution was removed by decantation, followed by washing of the and the effect of time on the percent swellability was also carried out at sample to neutral pH with deionized water, filteration and air-drying. time intervals of 10, 20, 30, 40, 50, and 60 minutes, at a fixed pH of 2. The sample obtained from the decalcification process was dispersed Swelling kinetic experiment: The swelling kinetic experiment in 1.5 L of 0.3% (v/v) solution of NaOCl (containing 12.5% available was carried out by measuring the weights of the hydrogels up to the chlorine). The mixture was allowed to stand for 1 hour and the excess equilibrium swelling state. Dry hydrogels of known weigths were kept NaOCl removed by decantation, followed by washing to neutral pH with in water at 27°C for 3 hours to allow them swell up to equilibrium, using deionized water and air drying to obtain chitin. The chitin was treated with 1.4 L of 50% NaOH solution (i.e., 12.5 M) for 20 minutes at 120°C. the method of Bamgbose et al. The S at equilibrium (Seq) can be got The solution was allowed to cool, then, the excess NaOH solution was using Equation (2). removed by decantation, followed by washing of the sample to neutral ds pH, filteration with a sintered glass and air drying to obtain chitosan. = k1 ( Seq − S ) (2) dt Preparation of chitosan hydrogels where Weq is the swollen weight of hydrogels at equilibrium. Preparation of uncrosslinked chitosan hydrogel: 1.5 g of Results and Discussion chitosan was dissolved in 20.0 mL of 2.0% aqueous acetic acid at room temperature with continuous stirring for 24 hours to obtain a pale Result of FTIR analysis of the uncrosslinked and crosslinked yellow viscous chitosan solution. Few drops of 0.5% tween-80 were chitosan hydrogels added to the solution for uniform dispersion and to prevent aggregation The FTIR spectrum of uncrossslinked chitosan hydrogel presented at ambient temperature during stirring. The chitosan solution was in Figure 1 shows a broad band at 3451 cm-1, attributed to O-H filtered with a sintered glass crucible to remove any undissolved matter. stretching, which overlaps the N-H stretching in the same region. The viscous solution was cast into petri dishes and dried overnight at The band at 2931 cm-1 represents -CH2 aliphatic groups. The band at room temperature to obtain the hydrogels. The semi-dried hydrogels 1652 cm-1 is the N-H bending vibration. The bands at 1461 cm-1 and were further dried in an oven at 45°C for 12 hours to completely remove 1384 cm-1 are the C-H bending vibrations of alkyl and methyl groups the residual solvent. respectively. The methyl group may have come from the acetic acid Preparation of crosslinked chitosan hydrogel: In a typical used as solvent in the preparation of the chitosan hydrogel. The bands J Phys Chem Biophys, an open access journal ISSN: 2161-0398 Volume 7 Issue 3 1000256 Citation: Akakuru OU, Isiuku BO (2017) Chitosan Hydrogels and their Glutaraldehyde-Crosslinked Counterparts as Potential Drug Release and Tissue Engineering Systems - Synthesis, Characterization, Swelling Kinetics and Mechanism. J Phys Chem Biophys 7: 256. doi: 10.4172/2161- 0398.1000256 Page 3 of 7 Figure 1: FTIR spectra of chitosan hydrogel. at 1167 cm-1 and 1045 cm-1 are attributed to -C-O-C- glycosidic linkage nucleophilic attack of the nitrogen atoms to the carbonyl carbons of in the chitosan ring. glutaraldehyde. As a result of this, there is reduction in water absorption sites in the crosslinked hydrogels. This explains why the uncrosslinked The FTIR spectrum of the crosslinked chitosan hydrogel presented chitosan hydrogel exhibits a higher swellability with time, when in Figure 2, shows bands at 3417 cm-1, O-H stretching which overlaps the compared with the crosslinked hydrogels. N-H stretching in the same region, 2925 cm-1 and 2365 cm-1 attributed to the -CH2 aliphatic groups, 1461 cm-1 and 1384 cm-1 represent the C-H The mechanism for the reaction between the amino groups of bending vibrations of alkyl and methyl groups respectively, 1167 cm-1 chitosan and the carbonyl groups of glutaraldehyde as summarized by and 1028 cm-1 which are attributed to the -C-O-C- glycosidic linkage, is shown in Figure 5. and an N-H bending vibration at 1635 cm-1 which has a reduced In general, the swellability of chitosan and its hydrogel are affected intensity and has moved to a lower wavenumber when compared with by three factors: the N-H bending vibration of uncrosslinked chitosan hydrogel at 1652 cm-1. This can be attributed to the effective crosslinking of chitosan 1. Presence of hydroxyl (-OH) groups in the chitosan chain, which hydrogel with glutaraldehyde, which occurred at the amino groups of enhance their hydrophilicity. chitosan. 2. Presence of amino (-NH2) groups in the chitosan chain, which Results of the swellability test on the chitosan hydrogels get protonated in water, mostly in acidic medium. The appearance of the cast film of a chitosan hydrogel showing 3. Flexibility of the chitosan polymeric matrix, which can allow for homogeneity is presented in Figure 3. easy penetration of the solution. Effect of time: The results of the percent swellability studies Effect of pH: The effect of pH on the percent swelability of at varying time intervals of the uncrosslinked and glutaraldehyde- uncrosslinked and crosslinked chitosan hydrogels is as represented crosslinked chitosan hydrogels with different crosslink densities are as in Figure 6. The results in Figure 6 for the dependence of percent presented in Figure 4. The results represented in Figure 4 show that the swellability on pH shows that all the chitosan hydrogels exhibited percent swellability of the uncrosslinked chitosan hydrogel increases as high swellability at low pH values of 2 to 4, with a rapid decline at time increases. This is because of the hydrophilic nature of chitosan, pH 8. The uncrosslinked chitosan hydrogel swelled more than the which is as a result of the presence of -OH groups in chitosan and the crosslinked hydrogels at all the pH values of 2 up to 8. Generally, the flexible nature of the matrix. Additionally, the percent swellability of the percent swellability of the crosslinked hydrogels increases as crosslink crosslinked hydrogels increases as their crosslink densities increase but density increases at pH 2 and pH 4 in the order of crosslink density the extent is lower than that for the uncrosslinked chitosan hydrogel. 1.50>1.00>0.75 but decreases at pH 6 and pH 8. In the first 10 minutes, the percent swellability was about 70% for the uncrosslinked hydrogel and between 35% and 40% depending on the At low pH, protonation of the amino groups of chitosan takes crosslink density for the crosslinked chitosan hydrogels. This is because, place, leading to repulsion in the polymer chains and the dissociation crosslinking of the chitosan with glutaraldehyde occurs at the amino of secondary interactions such as intramolecular hydrogen bonding, groups (-NH2) of the chitosan and this is aided by the lone pair of allowing more water into the gel network. At high pH, deprotonation electrons on the nitrogen atoms of the amino groups, resulting in the of amino groups ensue, repulsion in the polymer chains is receded and J Phys Chem Biophys, an open access journal ISSN: 2161-0398 Volume 7 Issue 3 1000256 Citation: Akakuru OU, Isiuku BO (2017) Chitosan Hydrogels and their Glutaraldehyde-Crosslinked Counterparts as Potential Drug Release and Tissue Engineering Systems - Synthesis, Characterization, Swelling Kinetics and Mechanism. J Phys Chem Biophys 7: 256. doi: 10.4172/2161- 0398.1000256 Page 4 of 7 Figure 2: FTIR spectrum of glutaraldehyde crosslinked chitosan hydrogel. 140 120 100 80 Uncrosslinked 60 1.50 CD 1.00 CD 40 0.75 CD 20 0 0 10 20 30 40 50 60 Time (minutes) Figure 4: Effect of time on the percent swellability of uncrosslinked and glutaraldehyde-crosslinked chitosan hydrogels. ds Figure 3: Overall view of chitosan hydrogel. = k1 ( Seq − S ) (3) dt where k1 is the first order rate constant. this allows contraction of their polymer matrices which tends to restrict intake of water. In addition, crosslinking is known to make the gelled Integrating Equation (3) between the limits of S=0 at t=0 and S=S matrix more compact, thus, no significant water can penetrate, and as at t=t, we have that a result, there will be a reduction in swelling and an eventual collapse  Seq  of the polymer matrix. These explain why the crosslinked hydrogels ln  S −S  = k1t (4) showed reduced swelling when compared with the uncrosslinked  eq  hydrogel. Plot of ln(Seq/(Seq-S)) against t for the uncrosslinked and crosslinked Results of the swelling kinetic experiment chitosan hydrogels is presented in Figure 7. The kinetic order which the swelling of the hydrogels follows as well A plot of ln(Seq/(Seq - S)) against t should have given a straight line but from Figure 7, curves were observed as against straight lines, as their rates of swelling can be determined, according to the method indicating that the swelling process of the hydrogels did not obey described by Druzynska et al.. Equation (4) and as such do not follow first-order kinetics. First-order kinetics: For a first order kinetics, the swelling rate at any time can be expressed thus: Second-order kinetics: The swelling rates of the hydrogels can be expressed as Equation (5) if one assumes these swelling rates follow J Phys Chem Biophys, an open access journal ISSN: 2161-0398 Volume 7 Issue 3 1000256 Citation: Akakuru OU, Isiuku BO (2017) Chitosan Hydrogels and their Glutaraldehyde-Crosslinked Counterparts as Potential Drug Release and Tissue Engineering Systems - Synthesis, Characterization, Swelling Kinetics and Mechanism. J Phys Chem Biophys 7: 256. doi: 10.4172/2161- 0398.1000256 Page 5 of 7 Figure 5: Reaction mechanism for the reaction between the amino group of chitosan and carbonyl groups of glutaraldehyde. Integrating Equation (5) between the limits of S=0 at t=0 and S=S 180 at t=t, we have that 160 k2 Seq2 t 140 S= (6) 120 1 + k2 Seq t Uncrosslinked 100 Rearranging Equation (6), we also have that 1.50 CD 80 1.00 CD t 1 1 60 = + (7) 0.75 CD S k 2 S e2q S eq 40 20 Equation (7) is the Schott’s equation. 0 Plots of t/S against t for the hydrogels should fit a straight line 2 4 6 8 pH and the values of Seq and k2 can be got from the slope (1/Seq) and the Figure 6: Effect of pH on the percent swellability of uncrosslinked and intercept (1/ k2 Seq2 ) of the plots. glutaraldehyde-crosslinked chitosan hydrogels. Plots of t/S against t for the uncrosslinked and crosslinked chitosan hydrogels is presented in Figure 8. 4 From Figure 8, it can be seen that our experimental data fit the 3.5 Schott’s equation over the range of values used in this study. The plots gave straight lines and calculated values for Seq ( Seqcalc. ) and the rate 3 constants k2 have been got from the slopes and intercepts of the plots ln(Seq/(Seq - S)) 2.5 respectively. 2 The values for S, experimentally determined S at equilibrium (S), 1.5 Uncrosslinked k2, and the correlation coefficients (R2) for both the uncrosslinked and 1 1.50 CD 1.00 CD crosslinked chitosan hydrogels are presented in Table 1. 0.5 0.75 CD 0 The results presented in Table 1 show that the kinetic model agreed 0 20 40 60 80 well with the swelling experiment with R2 values of up to 0.999. This t (minutes) shows good correlation between t/S values and those of t. It can also Figure 7: Plot of ln(Seq/(Seq-S)) against t for the uncrosslinked and crosslinked be seen from Table 1 that k2 increases as CD decreases, showing that hydrogels. the higher the extent of crosslinking of the chitosan matrix, the more difficult it becomes for solvent to penetrate such matrices. For instance, second-oreder kinetics. chitosan hydrogels with CD of 1.50 had k2 × 105 value of 22.500 while ds the chitosan hydrogel with CD of 0.75 had 40.000. Crosslinking of the = k2 ( Seq − S ) 2 (5) dt matrices lead to improved compactness of the matrices conferring such where k2 is the second-order rate constant. hydrogels with the ability to tightly hold incorporated drugs or genetic materials and release them at slower or more controlled rates than is J Phys Chem Biophys, an open access journal ISSN: 2161-0398 Volume 7 Issue 3 1000256 Citation: Akakuru OU, Isiuku BO (2017) Chitosan Hydrogels and their Glutaraldehyde-Crosslinked Counterparts as Potential Drug Release and Tissue Engineering Systems - Synthesis, Characterization, Swelling Kinetics and Mechanism. J Phys Chem Biophys 7: 256. doi: 10.4172/2161- 0398.1000256 Page 6 of 7 Bead Type n 1.4 Uncrosslinked NA 1.2 1.50 CD 0.142 1.00 CD 0.155 1 0.75 CD 0.150 0.8 Table 2: Swelling diffusion exponent (n) for uncrosslinked and crosslinked chitosan t/S Uncrosslinked 0.6 hydrogels. 1.50 CD 0.4 where k is a constant that depends on the morphology as well as the 1.00 CD interaction of the polymer network, Mt and Meq are the mass uptake of 0.2 0.75 CD water at time t and at equilibrium, respectively. The value of the swelling 0 diffusional exponent (n) determines the transport mode or diffusion 0 20 40 60 80 t (minutes) mechanism of water through the chitosan hydrogels. Equation (8) is only valid in analyzing the first 60% swelling of the hydrogels, Figure 8: Plot of t/S against t for the uncrosslinked and crosslinked chitosan irrespective of the geometry. hydrogels. To determine the nature of diffusion mechanism which the diffusion of water into the chitosan hydrogels follows, the swellability log t data generated in this study were fitted into the linearized form of 0 Equation (8) thus: 0 0.5 1 1.5 2 -0.05 Mt -0.1 log = logk + n log t (9) M eq log (Mt/Meq) -0.15 -0.2 A Fickian diffusion has an n value of 0.5 (case I transport) and -0.25 0.5˂n˂1.0 for an anomalous or non-Fickian diffusion. n˂0.5 for a less Fickian diffusion (also classified as Fickian diffusion) and n=1.0, -0.3 1.50 CD 1.00 CD for a relaxation controlled (case II transport) release. A super case II -0.35 0.75 CD transport which occurs occasionally, is attributed to cases where n˃1.0 -0.4. Plots of log(Mt/Meq) against logt gave straight lines as presented in -0.45 Figure 9 and the values of n for the hydrogels were got from the slopes -0.5 of the plots. Values of n for the swelling studies of both crosslinked and uncrosslinked chitosan hydrogels are presented in Table 2. The Figure 9: Plot of log(Mt/Meq) against logt for the chitosan hydrogels. symbol ‘NA’ represents hydrogel formulations that were not analyzed. This is due to the fact that S for such hydrogels were above 60 %, where Bead Type ( Seqcalc. ), ( Seqcalc. ), k2 × 105 (min-1) R2 Equation (8) is valid. The results presented in Table 2 show n values ranging from 0.142 to 0.155, indicating that the type of diffusion or Uncrosslinked 138.420 142.857 4.900 0.999 transport mode of water into the hydrogels is Less Fickian (also 1.50 CD 64.170 66.667 22.500 0.996 classified as Fickian diffusion)-where water diffusion rate is much 1.00 CD 52.310 55.556 32.400 0.999 below the polymer chain relaxation rate. 0.75 CD 48.950 50.000 40.000 0.999 Table 1: Second-order swelling kinetic parameters for the uncrosslinked and Conclusion crosslinked chitosan hydrogels. Chitosan was prepared from snail shells and was successfully modified by chemical crosslinking with glutaraldehyde. FTIR study of expected for uncrosslinked hydrogels. the crosslinked chitosan hydrogels showed a reduced intensity of the Diffusion mechanism of water into the hydrogels N-H bending vibration and at a lower wavenumber when compared with the N-H bending vibration of uncrosslinked chitosan hydrogel and When a swellable polymeric hydrogels such as chitosan hydrogels is this was attributed to the successful crosslinking of chitosan hydrogel brought into contact with water, the water will diffuse into the polymeric with glutaraldehyde, which occurred at the amino groups of chitosan. hydrogel and the hydrogel expands leading to its swelling. This diffusion The swelling abilities of the hydrogels have been studied at different involves the migration of water into pre-existing or dynamically formed pH values and it has been found that the swelling behaviour of the species between the polymeric chains of the hydrogel. The swelling of hydrogels followed first-order kinetics and depended on time and the these hydrogels involves larger scale segmental motion, leading to an pH of the medium, decreasing as pH increases and increasing as time ultimate increase in separation of the polymeric chains of the hydrogels. increased. Crosslinking of the hydrogels have also proved effective to The utility of the diffusion phenomena study of water into the polymeric compact the polymer blends and consequently decreasing the swelling hydrogels is to clarify the behaviour of the polymers. abilities of the hydrogels. The mechanism of penetration of water into In order to understand the type of diffusion of water into the the uncrosslinked and crosslinked hydrogels was by Less-Fickian type hydrogels, the simple and commonly used Korsmeyer-Peppas model of diffusion or transport mode. The results obtained in this study show , based on the power-law expression got from Fick’s second law of that the chitosan hydrogels can be efficient matrices for controlled drug diffusion was applied thus: delivery and tissue engineering. Crosslinking of the matrices has been determined in this study to be capable of reducing swellability of the Mt matrices, which can result in a decrease in the rate of drug delivery, with = kt n (8) M eq J Phys Chem Biophys, an open access journal ISSN: 2161-0398 Volume 7 Issue 3 1000256 Citation: Akakuru OU, Isiuku BO (2017) Chitosan Hydrogels and their Glutaraldehyde-Crosslinked Counterparts as Potential Drug Release and Tissue Engineering Systems - Synthesis, Characterization, Swelling Kinetics and Mechanism. J Phys Chem Biophys 7: 256. doi: 10.4172/2161- 0398.1000256 Page 7 of 7 increased potential for tissue engineering. intermediates. Quaternary tetraalkylammonium chitosan derivatives utilized in anion exchange chromatography for perchlorate removal. International Journal Acknowledgements of Molecular Sciences 16: 9064-9077. The authors appreciate the professional advice of Prof. Arthur Jideonwo of the 7. Okolo PO, Akakuru OU, Osuoji OU, Jideonwo A (2013) Studies on the Department of Chemistry, University of Benin, Nigeria. Properties of Chitosan-Starch Beads and their Application as Drug Release Materials. Bayero Journal of Pure and Applied Sciences 6: 118-126. References 8. Bansal V, Sharma PK, Sharma N, Pal OP, Malviya R (2011) Applications of chitosan and chitosan derivatives in drug delivery. Advances in Biological 1. Gierszewska-Drużyńska M, Ostrowska-Czubenko J (2015) Structual and Research 5: 28-37. swelling properties of hydrogel membranes based on chitosan crosslinked with glutaraldehyde and sodium tripolyphosphate. Progress on Chemistry and 9. 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Bhumkar DR, Pokharkar VB (2006) Studies on effect of pH on cross-linking of Materials Sciences and Applications 1: 162. chitosan with sodium tripolyphosphate: a technical note. AAPS Pharmscitech 7: E138-E143. 12. Chime SA, Onunkwo GC, Onyishi II (2013) Kinetics and mechanisms of drug release from swellable and non swellable matrices: A review. Res J Pharm Biol 5. Park I, Cheng J, Pisano AP, Lee ES, Jeong JH (2007) Low temperature, low Chem Sci 4: 97-103. pressure nanoimprinting of chitosan as a biomaterial for bionanotechnology applications. Applied Physics Letters 90: 093902. 13. Gierszewska-Drużyńska M, Ostrowska-Czubenko J (2012) Mechanism of water diffusion into noncrosslinked and ionically crosslinked chitosan membranes. 6. Sayed S, Jardine A (2015) Chitosan derivatives as important biorefinery Prog Chem Appl Chitin Deriv 17: 59-66. J Phys Chem Biophys, an open access journal ISSN: 2161-0398 Volume 7 Issue 3 1000256