Several forms of Chlorin e6 and its derivatives are reported as efficient photosensitizers (PS) studied in Photodynamic Therapy (PDT) for oncologic applications. Fotolon® is a pure form of Chlorin e6 trisodium salt developed by Apocare Pharma.
The increasing prevalence of antibiotic resistance requires new approaches also for the treatment of infectious keratitis. Photodynamic Inactivation (PDI) using the photosensitizer (PS) Chlorin e6 (Ce6) was investigated as an alternative to antibiotic treatment. An in-vitro cornea model was established using porcine eyes. The uptake of Ce6 by bacteria and the diffusion of the PS in the individual layers of corneal tissue were investigated by fluorescence. After removal of the cornea’s epithelium Ce6-concentrations < 1 mM were sufficient to reach a penetration depth of 500 μm. Liquid cultures of microorganisms were irradiated using a specially constructed illumination chamber made of Spectralon(R) (reflectance: 99 %), which was equipped with high power light emitting diodes (λ = 670 nm). Clinical isolates of Staphylococcus aureus (SA) and Pseudomonas aeruginosa (PA) from keratitis patients were tested in liquid culture against different concentrations of Ce6 (1 - 512 μM) using 10 minutes irradiation (E = 18 J/cm2 ). This demonstrated that a complete inactivation of the pathogen strains were feasible whereby SA was slightly more susceptible than PA. 3909 mutants of the Keio collection of Escherichia coli (E.coli) were screened for potential resistance factors. The sensitive mutants can be grouped into three categories: transport mutants, mutants in lipopolysaccharide synthesis and mutants in the bacterial SOS-response. In conclusion PDI is seen as a promising therapy concept for infectious keratitis.
Helicobacter pylori (HP), a gram-negative microaerophilic bacterium located in gastric mucosa, plays an im-
portant role in gastro carcinogenesis. Due to the increasing emergence of antibiotic resistance, photodynamic
inactivation of bacteria presents a new approach to treat bacterial infections, like HP. In vitro experiments were
performed to determine the irradiation conditions for a complete inactivation of HP with the photosensitizer
Chlorin e6 (Ce6). The HP strain CCUG 38770 (Culture Collection, University of Gothenburg, Sweden) was
routinely cultured under microaerophilic conditions, suspended in sodium chloride, incubated with Ce6 and irradiated briefly with red light of the appropriate wavelength of λ = 660 nm. Series of measurements of different
Ce6-concentrations (0.1 μM - 100 μM) were carried out, whereby the incubation time was kept constant at 1
min. The absorbed energy dose has been selected in varying the irradiation time (1 s - 300 s) and the power
density (4.5 mW/cm2 - 31 mW/cm2 ). Quantification of inactivation was performed by enumeration of the grown colonies. In addition, the accumulation of Ce6 in HP cells was studied more precisely by
uorescence spectroscopy. With a Ce6 concentration of 100 μM and a power density of 9 mW cm2 , a 6-log10 reduction in the survival rate of HP was
achieved within 30 seconds of irradiation. In conclusion the most relevant factor for the inactivation of HP is the
exposure time of irradiation, followed by the concentration of Ce6 and the light intensity. Further studies with
HP strains obtained from patient specimens are under current investigation.
Photodynamic inactivation (PDI) of bacterial strains presents an attractive potential alternative to antibiotic therapies. Success is dependent on the effective accumulation in bacterial cells of photochemical substances called photosensitizers, which are usually porphyrins or their derivatives. The kinetics of porphyrin synthesis
after treatment with the precursor ALA and the accumulation of the Chlorin e6 and the following illumination were studied. The goal was to estimate effectivity of the destructive power of these PS
in vitro in respect of the physiological states of Mycobacteria. So the present results examine the cell destruction by PDI using ALA-induced Porphyrins and Chlorin e6 accumulated in Mycobacterium phlei and Mycobacterium smegmatis, which
serve as models for the important pathogens
Mycobacterium tuberculosis, Mycobacterium leprae and
Mycobacterium bovis. We could show that both Mycobacterium after ALA and Chlorin e6 application were killed by illumination with light of about 662 nm. A reduction of about 97% could be reached by using a lightdose of 70 mW/cm2.
To detect bronchial carcinoma by autofluorescence, we measured in-vivo, in an in-vivo model, and in-vitro the spectra of tumor and normal tissue by a fiber-optic-spectrometer. The main difference between tumor and bronchial tissue is the intensity of the 505 nm main peak.
The quantification of the fluorescence is important to design optical equipment for Photodynamic Diagnosis. The fluorescence intensity of Protoporphyrin IX in solution and induced in cells, cultivated in the hen's eggs model, have been measured photometrically. With an optimized CCD-camera-systems fluorescent tumor areas were detected before and after PDT. The ratio of dead cells was detected by staining with trypan blue after PDT. The measurements were carried out various energy densities at the time of maximal PpIX-enrichement.
The transition of the tumor fluorescence from auto fluorescence towards PpIX fluorescence was studied under spectral and spatial resolution in an in-vivo tumour model. Human tumour cells were embedded on the chorioallantois membrane (CAM) of fertilised hen's eggs. A time period of 8 days is sufficient to grow tumours of a size of several millimeters. After the application of ALA and h-ALA the intensity and the wavelength spectra of the fluorescence were observed under blue light exposure (lambda) = 405 nm) by the spectrometer SpectraCube. 1-2 hours after the application of the photosensitizer the spectra show the yield of the typical double peak structure of PpIX.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.