Photodynamic Effect on Photosensitized Candida albicans with Hematoporphyrin Derivative Using Low Power Diode Laser In Vitro

Ahmed S Al-Khafaji

doi:10.33899/rjs.2012.29057

Abstract

In this study, the Photodynamic Effect (PDE) of Hematoporphyrin derivative (HpD) combined with irradiation from low power laser on Candida albicans was investigated. Four isolates of C. albicans were diagnosed in seven samples collected from oral cavity of adults with dental caries. Laser irradiation used in this study has been emitting from Diode laser at a wavelength equal to 630 nm (red region of the spectrum), while the output power was approximately 10mW as a continuous wave. The exposure time of irradiation was between (30-240) seconds, irradiation area was (0.125) cm2. C. albicans were exposed to irradiation after its exposure to several concentrations of HpD these concentrations were varied from (16 -128) µg/ml. The results clearly showed the Photodynamic effect in killing C. albicans which was photosensitized by HpD in combination with laser irradiation. There was no determined effect on yeast cells viability neither by the using HpD concentrations nor irradiation doses separately. It could be concluded that PDE of HpD by low power laser irradiation at wavelength 630 nm on Candida albicans was a powerful technique in growth inhibition of that pathogenic yeast In vitro.

Highlights

Photodynamic Effect (PDE) is providing a technique of killing microorganisms in localized and topical infections (Malik et al, 1990; Wilson, 1993)
The effectiveness of the PDE in reducing cell viability had varied as a function of C. albicans and the association between Hematoporphyrin Derivative (HpD) and the irradiation (Fig. 1)
The survaival curve of photosensitized C. albicans showed a minimum influence by 30 sec of laser irradiation associated with concentration 16 μg/ml of HpD photosensitizer, these were necessary to achieve a minimal inhibition of C. albicans to approximately 10%. (Fig. 2)

Summary

Introduction

Photodynamic Effect (PDE) is providing a technique of killing microorganisms in localized and topical infections (Malik et al, 1990; Wilson, 1993) It can be defined as destruction of photosensitized cells by free radical ions such as singlet oxygen (1O2) produced by binary mechanism of a photosensitizing agent and irradiation of an appropriate wavelength (Dougherty et al, 1998). PDE includes delivering irradiation of the appropriate wavelength to excite the photosensitizing agent (photosensitizer) from ground or triplet state to singlet state This excited state may undergoing intersystem crossing to the slightly lower energy, which may react further by two processes known as Type I and Type II photochemical reactions, both of them require molecular oxygen (Ochsner et al, 1997).

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Conclusion