IEEE TRANSACTIONS ON MAGNETICS, VOL. 41, NO. 10, OCTOBER 2005 4111

In Vivo and in Vitro Investigation ofPhotosensitizer-Adsorbed Superparamagnetic

Nanoparticles for Photodynamic TherapyS. I. Park1, J. H. Lim2, J. H. Kim3, H. I. Yun2, and C. O. Kim1

Department of Materials Engineering, Chungnam National University, Daejeon 305-764, KoreaDivision of Veterinary Pharmacology and Toxicology, Chungnam National University, Daejeon 305-764, KoreaResearch Center for Advanced Magnetic Materials, Chungnam National University, Daejeon 305-764, Korea

Superparamagnetic particles of Fe3O4 were nanometrically synthesized by coprecipitation. Hematoporphyrin (HP) and 5-aminole-vulinic acid (ALA) were used as photosensitizers, which were adsorbed on magnetic particles. The adsorption rates of HP and ALAwere observed to 2.0% and 12.5% by UV spectrometry and the pico-tag method, respectively. The toxicity of the magnetic fluids wasestimated using Sprague–Dawley rats. The photodynamic effect of the photosensitizer-adsorbed magnetic fluids was examined with ahuman lung cancer cell, for which the light doses were applied to 400 mJ/cm3.

Index Terms—Cancer cell, in vivo, in vitro, magnetic particle, photodynamic therapy, photosensitizer.

I. INTRODUCTION

MAGNETIC nanoparticles have been developed for var-ious applications by many researchers. Since such mag-

netic fine particles have a unique property, they can be appliedto special medical techniques [1]. As magnetic fluids are easilymoved to the target in a human body, they are effective for thediagnosis and treatment of tumors.

Photodynamic therapy (PDT) is usually used in combinationwith different cancer treatments such as radiation therapy, hy-perthermia, chemotherapy, and so on.

When the hematoporphyrin (HP) is injected into an affectedpart of the body, and the light source is introduced with the wavelength of 630 nm, the photosensitizer is activated in a cancer cellto generate the radical oxygen [2], [3]. The 5-aminolevulinicacid (ALA) is clinically applied to the skin tumor which is diffi-cult to surgically operate upon [4], [5]. In this paper, two kindsof photosensitizers, HP and ALA, were applied to magneticfluids, and their adsorption rate was examined. A PDT effectof the photosensitizers on cancer cells was investigated by UVspectrometry. Also, the heat capacities of bare and photosensi-tizer-adsorbed magnetic nanoparticles were measured using asolution calorimeter from body temperature to a cure tempera-ture for the hyperthermia.

II. EXPERIMENT

A. Preparation of Photosensizier-Adsorbed MagneticNanoparticles

The magnetite nanoparticles were prepared with FeCl 4H Oand FeCl 6H O solutions and ammonia water by chemical co-precipitation. Its temperature was increased with strong stirring

Digital Object Identifier 10.1109/TMAG.2005.854462

up to 80 C. In order to control the size of the magnetic parti-cles [6], [7], the excess alkali solution was added. Decanoic acidand nonanoic acid were used as first and second surfactants forpreparing the water-based magnetic fluids, respectively. Afterwashing with acetone and water, an electrolyte was separatedand removed by magnetic decantation. In the case of the pho-tosensitizer, HP was inserted between the first and second sur-factants, while ALA was directly adsorbed on the particles withthe only outlayer surfactant. The adsorption of HP and ALA onthe magnetic particles was quantitatively observed using a UVspectrometer (SHIMADZU UV-3101PC) and pico-tag aminoacid analyzer (Fluorometric Analysis System, waters 510 HPLCpump), respectively.

B. Cell Line and PDT Process

A human lung cancer cell, A549 (Korean Cell Line Bank),was selected as the cell specimen. The cancer cell was cultivatedas the cell for 24 h with the solution of RPMI 1640 and 10% FBSin a 5% CO incubator of water jacket type (Astec Co.).

The cell number was controlled to 1 10 per dish by haema-cytometer. ALA 0.1 and HP 0.2 mol/ml adsorbed in the mag-netic fluid were separately inserted into the raw cell, and thesecells were stored in an incubator for 25 h for penetration of themagnetic nanoparticles. The remanents were washed three timeswith the cultivated solution and then a lighting dose of laser wasapplied to each sample for 10 min with different energy densitiesof 0, 50, 200, and 400 mJ/cm . After light emitting, the samplesmixed with the cultivated solution were filled to 0.1 ml in watersoluble tetrazolium salt (WST) of cell counting kit-8 and werestored in the incubator for 6 h.

The normal cells in metabolism are reduced to hydrophilicWST, with which the color is changed from yellow to purpleby the enzyme effect due to dehydrogenation of mitochondria.Thus, the living cell was observed with UV absorbance.

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4112 IEEE TRANSACTIONS ON MAGNETICS, VOL. 41, NO. 10, OCTOBER 2005

Fig. 1. (a) UV absorption spectra of adsorbed in magnetic fluids at various adding amounts of hematoporphyrin and (b) their regression graph.

Fig. 2. Concentrations of several species of amino acid adsorbed in magneticfluids from ALA of 2�10 mol/l.

C. Animal Model

Male Sprague–Dawley rats, weighing between 190 and 220 gat the age of 6–7 weeks, were used for a clinical demonstration.All animals of each group were treated by the intravenous ad-ministration of the physiological salt solution and magnetic fluidthrough the tail vein.

III. RESULTS AND DISCUSSION

A. Adsorption Rate of Photosensitizers

Fig. 1 shows the UV absorbance for evaluating the concen-tration of HP adsorbed on the magnetic nanoparticles at variousits adding amounts.

Fig. 2 shows the concentration for some important species ofamino acid adsorbed on the magnetic nanoparticles at the ad-dition of 2 10 mol/l ALA. The adsorption rate of the pho-tosensitizers was obtained from these observations, which was2.0% and 12.5% for HP and ALA, respectively.

B. In Vitro Specificity

Fig. 3 shows the survival intensity of cells observed inUV analysis. The intensities were indicated by the reduction

Fig. 3. Comparison of viability for cancer cells with magnetic particles appliedby hematoporphyrin and ALA acid at different lighting doses.

of WST. In the case of ALA, the cell destruction increasedproportionally with rising lighting doses, while in the case ofHP, the remarkable cell destruction was not observed exceptfor 400 mJ/cm . This difference of viability is caused by theamount of photosensitizer adsorbed on the surface of magneticnanoparticles.

C. In Vivo Specificity

The toxicity estimation and in vivo test were performed onmagnetic fluids with the adsorbed HP and ALA. Raw HP andALA solutions of the same volume were separately injected intoHeLa cellular tissues originating from a uterine cancer. After theraw photosensitizer solution and the photosensitizer-adsorbedmagnetic fluid were injected into rats, their distribution aspectin liver, kidney, and lung was examined by H & E and Prussianblue dyeing and by using a confocal microscope.

As a result, there was no meaningful difference in the via-bility of the rat even though several types of photosensitizerswere administrated. In the case of excess injection of the mag-netic fluids, the toxicity was similar to ironic poisoning. Whenthe photosensitizer-adsorbed magnetic fluids were injected with4% to a total blood amount, all rats were dead. The cellular

PARK et al.: IN VIVO AND IN VITRO INVESTIGATION OF PHOTOSENSITIZER-ADSORBED NANOPARTICLES 4113

Fig. 4. Difference of heat capacity between bare and photosensitizer-adsorbednanoparticles.

pathological test revealed that iron in the magnetic fluid wasadsorbed in a body and was eliminated by the network endothe-lium system.

D. Heat Capacity of Magnetic Particles

Fig. 4 shows the variation of heat capacity for some kindsof nanoparticles. The capacity value of the photosensitizer-ad-sorbed nanoparticles was about 4 kcal/g lower than that of thebare one. The reason is ascribed to the adsorption layers whichdisturbs the emission of heat generated from the magnetic core.

IV. CONCLUSION

The magnetic fluids were prepared to apply to the photody-namic therapy. The photosensitizers of HP and ALA were ad-sorbed on the magnetic nanoparticles.

The adsorption rate was increased to 12.5% with ALA com-pared with 2% of HP. The improved adsorption of the photosen-sitizer on the magnetic particles was more effective to destroythe cancer cell in the photodynamic therapy.

ACKNOWLEDGMENT

This work was supported by the Korean Science and Engi-neering Foundation through the Research Center for AdvancedMagnetic Materials, Chungnam National University.

REFERENCES

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[3] A. K. Haylett, F. I. McNair, D. McGarvey, N. J. F. Dodd, E. Forbes, G.Truscott, and J. V. Moore, “Singlet oxygen and superoxide characteris-tics of a series of novel asymmetric photosensitizers,” Cancer Lett., vol.112, p. 233, 1997.

[4] J. C. Kennedy, R. H. Pottier, and D. C. Pross, “Photodynamic therapywith endogenous protoporphyrin IX: Basic principle and present clinicalexperience,” J. Photochem Photobiol. B Biol., vol. 6, p. 143, 1990.

[5] J. C. Kennedy and R. H. Pottier, “Endogenous protporphyrin IX, aclinical useful photosensitizer for photodynamic therapy,” J. PhotochemPhotobiol. B Biol., vol. 14, p. 275, 1992.

[6] S. I. Park, J. H. Kim, and C. O. Kim, “Preparation of photosensitizer-coated magnetic fluid for treatment of tumor,” J. Magn. Magn. Mater.,vol. 272–276, p. 2340, 2004.

[7] S. I. Park, J. H. Lim, J. H. Kim, H. I. Yun, J. S. Roh, C. G. Kim, andC. O. Kim, “Effects of surfactant on properties of magnetic fluids forbiomedical application,” Phys. Stat. Sol. (b), vol. 241, p. 1662, 2004.

Manuscript received February 7, 2005.