synthesis and characterization of layer by layer magnetic ... - wjpps

WORLD JOURNAL OF PHARMACY AND PHARMACEUTICAL SCIENCES

Shanmugavel et al.

World Journal of Pharmacy and Pharmaceutical Sciences

Volume 3, Issue 2, 1809-1824.

Research Article

ISSN 2278 – 4357

SYNTHESIS AND CHARACTERIZATION OF LAYER BY LAYER MAGNETIC NANOPARTICLES OF METHOTREXATE AND MELPHALAN Subbarayan Shanmugavel 1*, Venkatachalam Karthikeyan2 1

Department of Pharmaceutical technology, Anna University, Thiruchirapalli, Tamil Nadu, India. 2

Assistant Professor, Cherraan’s College of Pharmacy, Coimbatore, Tamil Nadu, India.

Article Received on 30 November 2013, Revised on 20 December 2013, Accepted on 19 January 2014

ABSTRACT Synthesize of polystyrene nanoparticle by using Pickering emulsion Polymerization method without using surfactant. Designing of a magnetic nano core /shell assembly by using polystyrene nanoparticles as templates in which chitosan polymer as shell material and a

*Correspondence for

hydrophilic anticancer drug (Methotrexate and Melphalan) are loaded

Author:

into the core. Surface coating of the designed core/shell assembly with

Subbarayan Shanmugavel

polyelectrolyte (sodium alginate). Step by step characterization in the

Department of Pharmaceutical technology, Anna University, Thiruchirapalli, Tamil Nadu,

experiment to conform the chemical reactions involved in each step. The size of the formulations was found to be 250-300nm. Surface morphology was analyzed by scanning electron microscope and it was

India.

spherical in nature. Magnetic property was evaluated by vibrating sample magnetometer which gives a hysteresis loop with magnetization value 50emu/g indicates that the super paramagnetic nature of the formulation. Tumour targeting is possible by the synthesized magnetic nanocarrier by means of using magnetic field to carry the nanocarrier towards the tumor site. Targeted and controlled drug delivery for combination (three in one) of drugs is being possible by the formulated layer- bylayer magnetic nanoparticles, it may have great potential in chemotherapy of cancer. Keywords: Methotrexate; Melphalan; Magnetic nanoparticles; Chitosan; Sodium alginate; drug targeting.

www.wjpps.com

Vol 3, Issue 2, 2014.

1809

Shanmugavel et al.

World Journal of Pharmacy and Pharmaceutical Sciences

INTRODUCTION Cancer is an unrestrained disease but its fate is still unresolved. No doubt in the last few decades scientists have shown the improvement to defeat this disease but are still not able to eradicate cancer from society. Chemotherapy using nanoparticles has been studied in clinical trials for several years and lots of studies have been published in this regards. Cancer nanotechnology which is an interdisciplinary research, cutting across the disciplines of biology, chemistry, engineering, physics & medicine is superior to surgery, radiation treatments, chemotherapeutic agents, photodynamic therapy, hormonal treatments and angiogenesis [1]. Nanotechnology is applied widely to offer targeted drug therapy, diagnostics, tissue regeneration, cell culture, biosensors and other tools in the field of molecular biology. To minimize drug degradation and loss, to prevent harmful side-effects and to increase drug bioavailability and the fraction of the drug accumulated in the required zone [2, 3]. Magnetic nanoparticles show remarkable new phenomena such as super paramagnetism, high field irreversibility, high saturation field, extra anisotropy contributions or shifted loops after field cooling. These phenomena arise from finite size and surface effects that dominate the magnetic behaviour of individual nanoparticles [4, 5]. The main advantages of magnetic (organic or inorganic) NPs[6,7] are that they can be: (i) visualized (superparamagnetic NPs are used in MRI); (ii) guided or held in place by means of a magnetic field; and (iii) heated in a magnetic field to trigger drug release or to produce Hyperthermia/ablation of tissue. The other advantages of magnetic nanoparticles drug delivery systems include (i) the ability to target specific locations in the body; (ii) the reduction of the quantity of drug needed to attain a particular concentration in the vicinity of the target; and (iii) the reduction of the concentration of the drug at non target sites minimizing severe side effects. Magnetic drug targeting may be defined as “the specific delivery of chemotherapeutic agents to their desired targets, e.g., tumors, by using magnetic nanoparticles (ferro fluids) bound to these agents and an external magnetic field which is focused on the tumor”. This type of tumor targeting is aimed at concentrating the toxic drug at the tumor cells to enhance the efficacy and reduce systemic toxicity of the drug [8, 9]. Iron oxide magnetic nanoparticles tend to be either paramagnetic or super paramagnetic, with particles approximately 20 nm being classed as the latter. In most cases super paramagnetic particles (usually Fe2O3 and Fe3O4) are of interest for in vivo applications, as they do not retain any magnetism after removal of the www.wjpps.com

Vol 3, Issue 2, 2014.

1810

Shanmugavel et al.

World Journal of Pharmacy and Pharmaceutical Sciences

magnetic field. This is important as large domain magnetic and paramagnetic materials aggregate after exposure to a magnetic field [10]. Methotrexate (MTX) is one of the most common anticancer drugs used for many tumors especially acute lymphoblastic anemia and several other diseases like choriocarcinoma, psoriasis, sarcoidosis and trophoblastic tumors chemotherapy so far. However some problems such as high toxicity and short plasma half-life, have limited its use

[11]

. Melphalan (MEL)

belonging alkylating agent in chemotherapy in the treatment of variety of cancers such as multiple myeloma, ovarian cancer and late stage of breast cancer. However its limited due to wide variety of untoward side effects and shortcomings such as non-specificity, short half life and multi drug resistance (MDR). MDR is the main cause of chemotherapy failure

[12]

. To

overcome all these limitations, this present study designed both drugs formulated into layer by layer magnetic nanoparticles which have advantage of bypass its high toxicity and achieved site specific release. MATERIALS AND METHODS Materials required Anticancer raw materials Methotrexate is received as gift sample (5gm, 99.7% purity) from GlaxoSmithKline Pharmaceuticals Limited, Mumbai. Melphalan is received as gift sample (8gm, 99.85% purity) from Celon labs, Hyderabad. Chemicals and solvents Ferric Chloride, Ferrous chloride (SR) and Tetrahydrofuran (THF), were purchased from Sd fine chem.-limited, Mumbai. Sodium alginate (SR) was purchased from Loba Chemie laboratory reagents & fine chemicals, Mumbai. Styrene (SR) was obtained from Kemphasol chemicals, Mumbai. Potassium per sulphate (AR) was purchased from RFCL Limited, New Delhi and Chitosan (AR) from Sigma Aldrich Chemicals- Pvt Ltd, Bangalore. Equipments Mechanical stirrer with RPM control, Magnetic stirrer with RPM control, Heating mantle, Hot plate, Thermometer, Centrifuge and Vacuum evaporator from Remi equipments, Mumbai. Bath Sonicator (Lisan instruments Pvt. Ltd., Chennai) and UV spectroscopy (Shimadzu, Japan) were used in this experiment.

www.wjpps.com

Vol 3, Issue 2, 2014.

1811

Shanmugavel et al.

World Journal of Pharmacy and Pharmaceutical Sciences

EXPERIMENTAL METHODS Synthesis of magnetic Chitosan nanocarrier [13-16] Synthesis of polystyrene nanoparticles as templates by emulsion polymerization 20g of styrene monomer was added with 200ml of water containing 0.5% of tween20 and it was emulsified at 1000 RPM for 15 minutes to form stable oil in water emulsion. 1.5%w/w of potassium per- sulfate (polymerization initiator) to styrene was added into the emulsion and it was heated to 70oc under stirring at 1000 RPM for 6hr. After 6hr polymerization, polystyrene nanoparticles formulation (F1) was separated by centrifugation at 7,000 RPM for 15 minutes and washed with water and alcohol for 3 times. The product was dried in vacuum oven. Polystyrene nanoparticles formulation (F2) was formulated with 2.0%w/w of potassium per sulfate to styrene by using the same method. Sulphonation of polystyrene nanoparticles 5g of polystyrene nanoparticles F1 and F2 were separately dispersed in 25ml 95% sulphuric acid at 40°C under magnetic stirring for 24hr.Sulphonated polystyrene nanoparticles F1 and F2 were separated by centrifugation at 7,000 RPM for 15 minutes and alternatively washed with water and alcohol for 3 times. The product was dried in vacuum oven. Synthesis of polystyrene core / chitosan shell nano assembly 1g sulphonated polystyrene nanoparticles F1 and F2 were mixed with 2g chitosan was dissolved in 30ml acetic acid solution (2%v/v) and vigorously stirred for 2hr. Then the polystyrene core / chitosan shell nano assembly F1 and F2 were separated by centrifugation at 7,000 RPM for 15 minutes and washed with water for 3 times to remove free chitosan. Magnetization of core shell assembly 1g polystyrene core/chitosan shell nano assembly F1 and F2 were soaked in 2M ammonium hydroxide solution for 24hr and then dispersed into 20 ml water. 10 ml solution of 0.2M ferric chloride and 0.1M ferrous chloride in the molar ratio of 2:1 was added into the dispersion under magnetic stirring for 2hr. Magnetic core shell assembly of F1 and F2 were separated by using bar magnet and washed with water for three times. Preparation of magnetic chitosan hallow nanosphere The synthesized magnetic polystyrene core / chitosan shell nano assembly F1 and F2 were

www.wjpps.com

Vol 3, Issue 2, 2014.

1812

Shanmugavel et al.

World Journal of Pharmacy and Pharmaceutical Sciences

alternatively washed with tetrahydrofuran and water for three times to remove polystyrene core and kept in a vacuum oven for 12hrs before use. Drugs loading into magnetic chitosan hallow nanosphere Methotrexate and Melphalan anti-cancer drugs were chosen as model drug and loaded in different manner as showed in table 5. Magnetic chitosan hallow nanosphere was dispersed into 50ml of specified medium containing anti-cancer drug(s) and it was stirred for two days by using magnetic stirrer (500 RPM). Drug loaded chitosan nanosphere was separated by magnetic field (Table 1). Table 1: Drugs loading into magnetic chitosan hallow nanosphere Formulation Anti-cancer drug(s)

Chitosan hallow Medium nanosphere F1-20mg

pH 6.4 phosphate buffer

and F1-20mg

Melphalan dissolved in

F1a

Methotrxate 10mg

F2b

Methotrexate

Melphalan each 5mg

20ml with

ethanol

mixed

Methotrexate

dissolved in 30ml pH 6.4 phosphate buffer F2-20mg

pH 6.4 phosphate buffer

and F2-20mg

Melphalan dissolved in

F1a

Methotrexate 10mg

F2b

Methotrexate

Melphalan each 5mg

20ml with

ethanol

mixed

Methotrexate

dissolved in 30ml pH 6.4 phosphate buffer Sodium alginate and chitosan layer by layer coating of drug loaded formulations 10mg of each formulation was coated with sodium alginate (SA) by stirring at 500RPM with 20 mg of SA in 20ml aqueous solution for 30 minutes. SA coated magnetic nano assembly was separated and washed with water for two times. Subsequently the formulation was coated with 20mg chitosan in 20ml 1% glacial acetic acid with stirring at 500RPM and the uncoated chitosan was removed by washing with water and centrifugation at 7000RPM. Chitosan coated magnetic nano assembly was further coated with SA by the same method. The resulting products of F1a, F1b, F2a and F2b were contains three layers in the order of SA/

www.wjpps.com

Vol 3, Issue 2, 2014.

1813

Shanmugavel et al.

World Journal of Pharmacy and Pharmaceutical Sciences

chitosan/ SA. CHARACTERIZATION Evaluation of reaction kinetics of polystyrene polymerization [17, 18] Polystyrene polymerization reactions were conducted by using different initiator concentration with respect to the monomer i.e. 0.01%w/w, 0.5%w/w and 1.5%w/w of potassium per sulphate to styrene and all other parameters were kept as constant. Polymerization reactions were conducted by using the procedure as follows. 5.0g of styrene monomer was added with 100ml of zinc oxide nanoparticle dispersion and it was emulsified at 1000 RPM for 15 minutes to form stable oil in water emulsion. Defined amount of potassium per- sulfate (polymerization initiator) to styrene was added into the emulsion and it was heated to 70oc under stirring at 1000 RPM. 0.1ml of reaction medium was taken at different time intervals and the total absorbance at 273.2nm (λ max of styrene found from UV spectrum) was calculated and all the values are tabulated. Reaction time and the total absorbance values were plotted in “X “and “Y” axis respectively. From the shape of the curve, the type of polymerization reaction kinetics was evaluated. The half reaction time t1/2 and reaction constant K values for each initiator concentration were calculated. Component characterization of the chitosan hallow nano sphere [19] It was very important to conform the removal of the polystyrene core by THF during the formation of chitosan hallow sphere. Removal polystyrene was confirmed by taking FT-IR spectra for sulphonated polystyrene, pure chitosan and chitosan hallow sphere by using a Bruker EQUINOX 55 Fourier Transform infrared (FT-IR) spectroscopy. The spectrum of chitosan hallow sphere should match with pure chitosan. Nanocarrier compatibility with drugs The synthesized nanoparticles, drugs and the mixer of both were characterized by using a Bruker EQUINOX 55 Fourier Transform infrared (FT-IR) spectroscopy to conform the compatibility of the drugs to nanocarrier. Particle size analysis [20] Particle size and polydispersity index of the formulation F1a and F1b before and after polyelectrolyte coating were analyzed by Malvern particle sizer, UK. Formulations were dispersed in water and analyzed for its light scattering pattern. Depending upon the light scattering property the particle size was evaluated. From the size distribution of formulation

www.wjpps.com

Vol 3, Issue 2, 2014.

1814

Shanmugavel et al.

World Journal of Pharmacy and Pharmaceutical Sciences

the polydispersity index was calculated and recorded in a system connected to the particle sizer. Surface charge analysis Zeta potential (surface charge) measurement of formulation F1a and F2a were performed by using Malvern Zetasizer (MAL 000967). The zeta potential of the formulation was determined by laser Doppler anemometry using a Malvern zetasizer. The instrument is a laser-based multiple angle particle electrophoresis analyzer. Using Doppler frequency shifts in the dynamic light scattering from particles, the instrument measures the electrophoretic mobility (or zeta potential) distribution together with the hydrodynamic size of particles in liquid suspensions by photon correlation spectroscopy. Measurements were performed at 25 ± 0.10 ºC, on samples appropriately diluted with water. The distribution of the surface charge was recorded as graph with help of a data processor. Surface morphology of nanoparticles Field emission scanning electron microscopy (FE-SEM; Hitachi S- 4700, Japan) was used to represent the surface morphology of the formulation F1a and F2a. A drop of diluted formulation dispersed in water was placed on a 400 mesh carbon-coated copper grid. After drying, the sample was sputter-coated with a gold-palladium alloy and it was analyzed at 5 kV electron voltages. Magnetization measurement and Magnetic susceptibility Vibrating sample magnetometer (VSM, Lakeshore, Model 7410 at 83 and 300K) was used for the magnetic properties of magnetic nanoparticle formulations with applied magnetic field 0- 2T at room temperature. A vibrating sample magnetometer (VSM) operates on Faraday's Law of Induction, which tells us that a changing magnetic field will produce an electric field. This electric field can be measured and can tell us information about the changing magnetic field. The Magnetic susceptibility of the formulated magnetic nanoparticle was determined using Fugro magnetic susceptibility meter. Magnetic susceptibility is the extent to which it is susceptible to induced magnetization by an external field. This is done by keeping the formulation at a distance of 1cm from the sensor.

www.wjpps.com

Vol 3, Issue 2, 2014.

1815

Shanmugavel et al.

World Journal of Pharmacy and Pharmaceutical Sciences

RESULT AND DISCUSSION Characterization: Polystyrene polymerization kinetics Corresponding reaction time and the total absorbance values for 0.01%w/w, 0.5%w/w and 1.5%w/w of initiator (potassium per sulphate) (Table 2). Table 2: Polymerization reaction kinetics

Reaction time in hrs 0 10 20 30 40 60 80 120 160 200 240

0.1%w/w initiator

Total absorbance 0.5%w/w initiator

1.5%w/w initiator

263.8 253.0 242.0 231.2 220.2 198.4 176.6 133.0 89.48 45.90 2.320

269.5 237.2 205.0 172.7 140.5 76.00 11.50 0.979 0.536 0.324 0.064

265.1 157.6 50.10 0.652 0.425 0.198 0.064 0.010 0.001 0 0

While plotting the reaction time and the total absorbance values in “X “and “Y” axis respectively as shown in graph 1a,1b and 1c, gives straight lines up to a particular time. So that it indicates the polymerization reaction fallows zero order kinetics up to that particular time (Fig.1).

Fig 1: Polymerization kinetics Within this time around 99.5% of styrene was polymerized to polystyrene which indicates the end of the reaction. After this time, due to depletion of styrene monomer to the initiator the reaction kinetics was deviated from the zero order kinetics. The reaction end time for polymerization involving initiator concentration 0.1%, 0.5%and 1.5% were found to be www.wjpps.com

Vol 3, Issue 2, 2014.

1816

Shanmugavel et al.

World Journal of Pharmacy and Pharmaceutical Sciences

240min, 80min and 20min respectively. From the above result it was concluded that while decreasing the initiator concentration it will increase the reaction time. Component characterization of the chitosan hallow nano sphere FT-IR spectrum of sulphonated poly styrene (Fig. 2) is shows the following peaks.

Fig 2: FT-IR spectrum of Sulphonated polystyrene  Peaks at 1600.99cm-1 and 1492.81 cm-1 are corresponding to the vibration of –C-C- in phenyl group.  The strong absorbance peaks at 3081.67 cm-1, 3059.29 cm-1, 3025.21 cm-1, 756.75 cm-1 and 697.54 cm-1 are corresponding to the vibration of hydrogen in the phenyl group.  Peaks at 1452.07 cm-1 and 1028.82 cm-1 are corresponding to sulphonic acid group present in the sulphonated polystyrene. FT-IR spectrum of pure chitosan (Fig. 3) showed the following peaks.

Fig 3: FT-IR spectrum of pure chitosan  The broad peak at 1593 cm-1 is corresponding to the amide bond.  A broad band at 3427.74 cm-1 is assigned to –OH bonded –NH absorption.  Peak at 1380.11 cm-1 is due to the presence of methylene groups.

www.wjpps.com

Vol 3, Issue 2, 2014.

1817

Shanmugavel et al.

World Journal of Pharmacy and Pharmaceutical Sciences

The FT-IR spectrum of chitosan hallow sphere is shown (Fig. 4). There are no peaks observed for the presence of sulphonated polystyrene and also it matches with the pure chitosan spectrum. Hence the sulphonated polystyrene templates were completely remove from the chitosan hallow sphere by the action of THF.

Fig 4: FT-IR spectrum of chitosan hallow Nanocarrier compatibility with drugs The FT-IR spectrums of methotrexate and melphalan and the physical mixture of chitosan nanocarrier and drugs are presented in (Fig. 5and 6) respectively and observed for the appearance any new peak. There is no appearance of new peak and significant change in the spectrum of the physical mixture which indicates the compatibility of the drugs with nanocarrier.

Fig 5: FT-IR spectrum of Methotrexate and Melphalan

www.wjpps.com

Vol 3, Issue 2, 2014.

1818

Shanmugavel et al.

World Journal of Pharmacy and Pharmaceutical Sciences

Fig 6: FT-IR spectrum of physical mixture of chitosan and drugs Particle size analysis The particle size analysis report was presented (Table 3). The particle size of the formulation F1a and F2a has increased after coating of polyelectrolyte to the extent of 64.9nm and 71.7nm due to the deposition of alternative layer of sodium alginate and chitosan. The particle size of the F1a was relatively small when compared to F2a. The reason for the smaller particle size of F1a is lesser amount of initiator (1.5%) used to fabricate polystyrene templates when compared to F2a (2.0%). The particle size less than 300nm show significant accumulation in cancer sites but less than 150nm will lead to phagocytic destruction. Hence, the formulations having the ability to accumulate into the cancer sites for long time. The polydispersity index of the formulations before and after coating was found to be less than 0.6 which indicates the homogeneous distribution of particle size (Fig. 7). Table 3: Particle size analysis- Report Formulation code

Average particle

Poly dispersity

size diameter (nm)

index

F1a- Before coating

199.0

0.301

F2a- Before coating

212.4

0.577

F1a- After coating

263.9

0.230

F2a- After coating

284.1

0.306

www.wjpps.com

Vol 3, Issue 2, 2014.

1819

Shanmugavel et al.

World Journal of Pharmacy and Pharmaceutical Sciences

7a (F1a)

7b (F2a) Fig 7: Particle size distribution Zeta potential measurement The zeta potential of the formulations F1a and F2a were found to be -38.8mV and -39.3mV respectively. Nanoparticle which having the zeta potential in between +30 to -30mV will tend to accumulate rapidly to form aggregates. The formulation F1a and F2a having zeta potential less than the limit. So the stability of formulations is fine (Figure 8).

www.wjpps.com

Vol 3, Issue 2, 2014.

1820

Shanmugavel et al.

World Journal of Pharmacy and Pharmaceutical Sciences

8(a) - F1a

8(b) - F2a Fig 8: Zeta potential measurement Surface morphology The surface morphology of the formulations F1a and F2a are showed (Figure 9). The surface morphology of the formulations was uniform and spherical in nature. The particles of formulation F2a was comparatively larger than F1a as that of particle size report.

www.wjpps.com

Vol 3, Issue 2, 2014.

1821

Shanmugavel et al.

World Journal of Pharmacy and Pharmaceutical Sciences

F1a

F2a Fig 9: SEM image

Magnetization measurement and Magnetic susceptibility Hysteresis curves (Figure 10) derived from the VSM analysis are proved the super paramagnetic nature of the formulation F1a and F2a. The magnetic hysteresis loop is also evident a fine magnetic sensitivity to the external magnetic field. The magnetization values for formulation F1a and F2a are 35.2emu/g and 43.4emu/g respectively. So that it is possible to shift the nanoparticles along with drugs to the cancer site by using external magnetic guide.

Fig 10: Hysteresis curves CONCLUSION Layer- by- layer magnetic nanoparticles has been successfully synthesized by using natural polymers i.e., chitosan and sodium alginate to achieve cancer site targeting and controlled drug delivery of anti- cancer drugs (Methotrexate and Melphalan). Methotrexate and melphalan in combination are successfully loaded into the formulated magnetic carrier. Since

www.wjpps.com

Vol 3, Issue 2, 2014.

1822

Shanmugavel et al.

World Journal of Pharmacy and Pharmaceutical Sciences

targeted and controlled drug delivery for combination (three in one) of drugs is being possible by the formulated layer- by- layer magnetic nanoparticles, it may have great potential in chemotherapy of cancer. ACKNOWLEDGEMENT The author thanking for all helping hands particularly Archbishop Casimir Instrumentation center (ACIC), St. Joseph College, Thiruchirapalli, Tamil Nadu, India for FT-IR studies and Central instrumentation facility, Sastra University, Tanjavur, Tamil Nadu, India for SEM studies. REFRENCES 1. Singh R, Prajapati SK, Khan R. Nanotechnology- advance progress for targeted therapy in cancer. World J Pharm. Pharm. Sci., 2013; 2(5): 3360-72. 2. Kagalkar AA, Nitave SA. Review: approach on novel drug delivery system. World J Pharm. Pharm. Sci., 2013; 2(5): 3449-61. 3. Surendiran A, Sandhiya S, Pradhan SC, Adithan C. Novel applications of nanotechnology in medicine. Ind J Med Res., 2009; 130 (6): 689-01. 4. Veiseh O, Gunn JW, Zhang M. Design and fabrication of magnetic nanoparticles for targeted drug delivery and imaging. Adv Drug Deliv Rev, 2010; 62:284–04. 5. Wahajuddin SA. Superparamagnetic iron oxide nanoparticles: magnetic nanoplatforms as drug carriers. Int. J. Nanomed., 2012; 7: 3445–71. 6. Indira TK, Lakshmi PK. Magnetic particle- A review. Int. J. Pharm. Sci. Nanotechnol., 2010; 3(3): 1035- 42. 7. Shaw SY, Chen YJ, Ou JJ, Ho LL. Preparation and characterization of Pseudomonas putida esterase immobilized on magnetic nanoparticles. Enzyme Microbe. Technol., 2006; 39: 1089-95. 8. Ho KM, Li P. Design and synthesis of novel magnetic core-shell polymeric particles. Langmuir, 2008; 24: 1801-07. 9. Sjögren CE, Johansson C, Naevestad A. Crystal size and properties of superparamagnetic iron oxide (SPIO) particles. Magn Reson Imaging, 1997; 15: 55–67. 10. Berry CC, Curtis SGA. Functionalization of magnetic nanoparticles for applications in biomedicine. Journal of Physics D: Applied Physics, 2003; (36):198–206. 11. Yousefi G, Foroutan SM, Zarghi A, Shafaati A. Synthesis and Characterization of Methotrexate Polyethylene Glycol Esters as a Drug Delivery System. Chem. Pharm. Bull.

www.wjpps.com

Vol 3, Issue 2, 2014.

1823

Shanmugavel et al.

World Journal of Pharmacy and Pharmaceutical Sciences

2010; 58(2) 147-53. 12. Xu J, Xu H, Newaz Z, Li R, Zhang Y, Liu H et al. Synthesis and characterization and in vitro drug release of Melphalan magnetic microspheres. Journal of nano research, 2013; 22: 31-40. 13. Mohanraj VJ, Chen Y. Nanoparticles - A Review. Trop. J. Pharm. Res., 2006; 5: 561-73. 14. Holister P, Weener JW, Román C, Harpe VT. Nanoparticles. Technology White Papers: Científica, Ltd., 2003.(Available at www.cientifica.com) 15. Li JH, Hong RY, Li HZ, Ding J, Zheng Y, Wei DG. Simple synthesis and magnetic properties of Fe3O4/BaSO4 multi-core/shell particles. Materials Chemistry and Physics, 2009; 113: 140-44. 16. Sun Y, Chen ZL, Yang XX, Huang P, Zhou XP, Du XX. Magnetic chitosan nanoparticles as a drug delivery system for targeting photodynamic therapy. Nanotechnology, 2009; 20: 135- 45. 17. Lachman L, Liberman HA, Kanig JL. Kinetic principles and stability testing: Theory and practice of industrial pharmacy. 3rd ed., Philadelphia; Lea & Febiger: 1990, pp.760-804 18. Siepmann J, Siepmann F. Mathematical modeling of drug delivery. International Journal of Pharmaceutics, 2008; 364(2): 328–43. 19. Beckett H, Stenlake JP. Practical pharmaceutical chemistry. 4th ed., Part 2, London: Athlone press; 1997, pp. 379-408. 20. He C, Hua Y, Yin L, Tang C, Chunhua Y. Effects of particle size and surface charge on cellular uptake and biodistribution of polymeric nanoparticles. Biomaterials, 2010; 31(13): 3657-66. 21. Zang LY, Zhu XJ, Sun HW, Chi GR, Xu JX, Sun YL. Control synthesis of magnetic Fe3O4-Chitosan nanoparticles under UV irradiation in aqueous system. Curr. Appl. Phys, 2010; 10: 828-33.

www.wjpps.com

Vol 3, Issue 2, 2014.

1824