Synthesis and characterization of chitosan nanoparticles used as drug carrier

Journal of Chemistry, Vol. 44 (1), P. 105 - 109, 2006<br /> <br /> <br /> SYNTHESIS AND CHARACTERIZATION OF CHITOSAN<br /> NANOPARTICLES USED AS DRUG CARRIER<br /> Received 20 December 2004<br /> Tran Dai Lam , Vu Dinh Hoang1, Le Ngoc Lien2, Nguyen Ngoc Thinh1,<br /> 1<br /> <br /> Pham Gia Dien2<br /> 1<br /> Faculty of Chemical Technology, Hanoi University of Technology<br /> 2<br /> Institute of Chemistry, Vietnamese Academy for Science and Technology<br /> <br /> <br /> summary<br /> The synthesis and characterization of chitosan (CS) nanoparticles used as drug carrier was<br /> reported. The formation of nanoparticles, taking place in an aqueous phase without using<br /> auxiliary toxic substances via the ionic interaction between NH3+ protonated group of CS and<br /> phosphate group of sodium tripolyphosphate (TPP) was monitored in situ by combined UV-vis<br /> and pH measurements. The synthesized nanoparticles were characterized by TGA/DTA, XRD and<br /> TEM. The particle size, estimated by TEM, was found around 50 - 70 nm, with a quite uniform<br /> size distribution.<br /> <br /> I - INTRODUCTION release and site-specific targeting of drug.<br /> Obviously, the properties of ionically<br /> Chitosan (CS) with excellent biodegradable crosslinked CS nanoparticles will be influenced<br /> and biocompatible characteristics is a naturally by the electrostatic interactions between<br /> occurring polysaccharide. Due to its unique counter-anions and CS. In this paper, these<br /> polymeric cationic character, CS has been interactions were investigated by means of<br /> extensively examined for the development of different methods like XRD, TG/DTA, IR, TEM<br /> drug delivery systems in the pharmaceutical in order to develop a biocompatible CS<br /> industry [1]. Up to now, drug delivery nanoparticles that could be used as drug carriers<br /> formulations based on CS (films beads, with enhanced drug release properties.<br /> microspheres, etc.) were usually prepared by<br /> chemical cross-linking agents like glutar- II - MATERIALS AND METHODS<br /> aldehyde. However, these chemical cross-<br /> linking agents could induce toxicity and other 1. Materials<br /> undesirable effects. To overcome this CS used was medical grade (MW = 200.000,<br /> disadvantage, reversible physical cross-linking determined by viscometry measurements; DA =<br /> agents like low molecular weight anions such as 70%, determined by IR analysis [3]),<br /> citrate, TPP were applied in the formulation pentasodium tripolyphosphate or TPP (Merck,<br /> preparation via electrostatic interactions [2]. Germany), CH3COOH (China), were of<br /> An important advantage of formulation analytical grade.<br /> preparation at nanoscale is that biocompatible 2. Methods of characterization<br /> and biodegradable polymer based nanoparticles<br /> could serve as drug carriers for controlled pH values were monitored by a digital<br /> <br /> 105<br /> Denver Instruments pH-meter with a precision the reported pKa as follows: TPP: pK1 = 1, pK2<br /> of ±0.01 at room temperature. = 2, pK3 = 2.79, pK4 = 6.47 and pK5 = 9.24; CS:<br /> UV-vis measurements were carried out at pKa= 6.3 [4].<br /> UV-vis Agilent 8453 spectrophotometer in the<br /> range of 300 - 800 nm. CH2OH<br /> O<br /> H<br /> FTIR spectra were recorded at FTIR- O<br /> IMPACT 400 Spectrometer with KBr discs. OH<br /> -<br /> OH H<br /> <br /> XRD patterns were obtained using D5000 H NH3+<br /> |<br /> X-ray Diffractometer, Siemens, Germany, with H NH3+ O<br /> H-O-P=O<br /> CuK radiation ( = 1.5406 Å) in the range of OH H<br /> O<br /> 10o < 2 < 60o. OH<br /> O<br /> H-O-P=O<br /> O O<br /> Particle size and the morphology was CH2OH H-O-P=O<br /> observed by TEM (EM-125K, voltage: 100 kV, n O<br /> |<br /> magnification ×100,000). H NH3+<br /> OH H<br /> Thermal analyses (TG/DTA) were O<br /> performed on NETZSCH STA 409 PC/PG H<br /> equipment, in nitrogen atmosphere. The O<br /> CH2OH<br /> temperature range was 30 - 800oC. The heating n<br /> rate is 5oC/min.<br /> (a) Deprotonation (b) Crosslinking<br /> III - RESULTS AND DISCUSSION<br /> Figure 1: Interaction mechanisms of between<br /> 1. Ionic interaction between CS and TPP CS and TPP<br /> Cationic CS could react with multivalent These changes were monitored in fixed<br /> counterions to form the intermolecular and/or wavelength mode at 420 nm and presented in<br /> intramolecular network structure (by ionic the Fig. 2. As it can be deduced from these<br /> interaction between NH3+ protonated groups and results, the interaction of CS with TPP is pH-<br /> negatively charged counterions of TPP). Due to sensitive and this interaction determined the<br /> hydrolysis, the small molecule polyelectrolyte, particle size, size distribution and also surface<br /> sodium TPP, dissociated in water and released properties, which in its turn, determines the drug<br /> out OH- ions, so, both OH- and P3O105- ions release properties.<br /> coexisted in the TPP solution and could<br /> 2. IR analysis<br /> ionically react with NH3+ of CS. Depending on<br /> pH values, the interaction mechanism might be To investigate CS-TPP nanoparticle<br /> deprotonation or ionic crosslinking, as described formation, FTIR spectra of CS, TPP and CS-TPP<br /> below (Fig. 1) [2]. nanoparticles were recorded. The main IR bands<br /> of pure CS and CS-TPP were reported in table 1.<br /> To study the nanoparticle formation at<br /> different pH values, combined pH and UV-vis From table 1, the presence of the P=O and<br /> measurements were carried out, first for TPP, P-O groups at the frequency of 1180 cm-1 and<br /> CS solutions separately and then for their 1250 cm-1, respectively; the band shifts (from<br /> mixture. These absorbance variations of TPP 1650 cm-1 and 1595 cm-1, corresponding to C-O<br /> and CS and CS-TPP could be correlated to their and N-H stretching, respectively in pure CS, to<br /> different degrees of ionization depending on pH 1636 cm-1 and 1539 cm-1 for CS-TPP<br /> values. Actually, the pH-dependent charge nanoparticles) clearly indicated the interaction<br /> numbers of TPP, were calculated according to between CS and TPP [5].<br /> <br /> <br /> 106<br />  4.5 (CS+TPP)<br /> Absorbance, a.u<br /> <br /> <br /> <br /> <br /> a.u<br /> 3.0<br /> 4.0<br /> <br /> <br /> <br /> <br /> Absorbance,<br /> 3.5<br /> 2.5<br /> 3.0<br /> <br /> 2.5<br /> 2.0<br /> 2.0<br /> <br /> <br /> <br /> <br /> ) (<br /> 1.5 1.5<br /> pH > 4,00<br /> 1.0 pH 3,90<br /> <br /> pH 3,80 1.0<br /> 0.5<br /> pH 3,75<br /> 0.0 pH 3,65<br /> pH 3,55<br /> 0.5<br /> -0.5<br /> <br /> -1.0<br /> 0.0<br /> -1.5<br /> 200 400 600 800 1000 1200<br /> 3.0 3.1 3.2 3.3 3.4 3.5 3.6<br /> Wavelength, nm pH<br /> Fig. 2: Absorbance variations during CS-TPP nanoparticle formation in function of pH<br /> Absorbance<br /> <br /> <br /> <br /> <br /> Wavenumber, cm-1<br /> Fig. 3: IR spectrum of CS-TPP nanoparticles<br /> Table 1: Main IR bands (cm-1) of the CS and CS-TPP nanoparticles<br /> Possible assignments Pure CS, /cm-1 CS-TPP nanoparticles, /cm-1<br /> O-, H-bonding<br /> 3429 3449<br /> N-H, in NH2<br /> <br /> C-H<br /> 2880 2920<br /> CO, amide I<br /> 1650 1636<br /> N-H, amide II<br /> 1595 1539<br /> C3-O<br /> 1400 - 1100 1382<br /> C6-O<br /> 1070; 1030 1071; 1020<br /> P-O<br /> 1250<br /> P=O<br /> 1180<br /> <br /> 107<br /> 3. XRD analysis be related to intermolecular and/or<br /> XRD patterns of CS, TPP and CS-TPP intramolecular network structure of CS,<br /> nanoparticles were recorded separately. While crosslinked to each other by TPP counterions.<br /> CS has a strong reflection at 2 = 22o, These interpenetrating polymer chains can<br /> corresponding to crystal forms II [6], CS-TPP imply certain disarray in chain alignment and<br /> nanoparticles has a weak and broad peak at 2 = consequently a certain decrease in crystallinity<br /> 25o, showing amorphous characteristics of of CS-TPP nanoparticles compared to pure CS<br /> nanoparticles. This structural modification can (Fig. 4).<br /> <br /> <br /> <br /> <br /> Fig. 4: XRD patterns of (a): pure CS and (b): CS-TPP nanoparticles<br /> <br /> 4. TG analysis characterization of CS-TPP nanoparticles was<br /> investigated by different methods (IR, UV-vis,<br /> Pure CS showed intensive loss of weight,<br /> XRD, TG, TEM). With the nanoscaled size,<br /> attributed to the decomposition of the polymer these nanoparticles can be used as drug carriers<br /> starting from 270oC to 400oC. For CS-TPP<br /> of some antimalarial agents in drug controlled<br /> nanoparticles, the loss of weight appears in the<br /> TG response from 197oC to 300oC (Fig. 5). 0<br /> 45 C<br /> These TG data showed some decrease of 0<br /> TG, %<br /> <br /> <br /> <br /> <br /> 100 121 C 0<br /> 270 C<br /> thermal stability of CS-TPP nanoparticles<br /> 90 0<br /> compared to pure CS which can be related to 63 C<br /> some distruption of the crystalline structure of 80<br /> 0<br /> 197 C<br /> CS.<br /> 70<br /> 5. TEM analysis 400 C<br /> 0<br /> <br /> 60<br /> The average size of CS-TPP particles was<br /> 0<br /> estimated about 60 - 70 nm. Their shape was 50 300 C<br /> CS-TPP<br /> spherical. Swelling of some of the particles to a<br /> 40 CS<br /> bigger size was detected. However, the size<br /> distribution was quite narrow (Fig. 6). 30<br /> 0 100 200 300 400 500 600 700 800 900<br /> <br /> IV - CONCLUSIONS Temperature, oC<br /> CS-TPP nanoparticles were synthesized by Fig. 5: TG graphs of pure CS and CS-TPP<br /> the reaction between CS and TPP. The nanoparticles<br /> 108<br />  30<br /> <br /> 25<br /> <br /> <br /> <br /> <br /> %<br /> 20<br /> <br /> 15<br /> <br /> 10<br /> <br /> 5<br /> <br /> 0<br /> 30 40 50 60 70 80 90 100 110<br /> Particle size, nm<br /> Fig. 6: TEM micrograph of CS-TPP nanoparticles and particle size distribution<br /> <br /> release systems. This research will be reported Sci., 3, No. 2, P. 234 - 258 (2000).<br /> in our next-coming publication. 2. X. Chu, K. Zhu. Europ. J. Pharm.<br /> Acknowledgements: This work was supported Biopharm., 54, P. 235 - 243 (2002).<br /> by a grant from the National Program in 3. T. Qurashi, H. Blair, S. Allen. J. Appl.<br /> Nanotechnology (81), for 2005 - 2006, Polym. 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