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Dye-sensitized photodynamic inactivation of cells
Abstract:
Living cells may be modified in diverse ways by the combined action of visible light and photosensitizing molecules. The effects appear most frequently as disruptions of subcellular structure, changes in surface membrane function or inhibition of mitotic ability. This review concentrates on the four most thoroughly studied cell types--yeast cells, nerve cells, erythrocytes, and cultured tumor cells. Research on these cells indicates that potency of sensitization depends at least as much on the factors affecting an association between sensitizer and cell prior to illumination as on photochemical properties. While sensitizers which permeate may lead to altered DNA, it appears that surface membrane modification occurs simultaneously and may be critical in the inactivation mechanism. There is much circumstantial evidence suggesting that excited singlet molecular oxygen acts as an intermediate between photoexcited sensitizer and target alteration. Proteins, lipids, and nucleic acids are all susceptible to photosensitized attack, but the correlation between cellular and molecular modification remains ill-defined. The use of the photodynamic process as a therapeutic technique, particularly in the treatment of malignant tumors, holds great promise, but awaits further research to develop greater selectivity of action.
Insights
Visible light and photosensitizers modify living cells, affecting structure and function. Cell-sensitizer interaction before light exposure is crucial for photodynamic effects, with singlet oxygen potentially mediating damage.
Area of Science:
- Cell Biology
- Photochemistry
- Biophysics
Background:
- Living cells can be altered by visible light and photosensitizing molecules.
- Observed effects include disrupted subcellular structures, altered membrane functions, and inhibited cell division.
Purpose of the Study:
- To review the effects of photosensitization on four key cell types: yeast, nerve, erythrocytes, and tumor cells.
- To explore the mechanisms and influencing factors of photosensitized cell modification.
Main Methods:
- Literature review focusing on yeast cells, nerve cells, erythrocytes, and cultured tumor cells.
- Analysis of factors influencing sensitizer-cell association and subsequent cellular responses.
Main Results:
- Photosensitizer-cell association prior to illumination is critical for sensitization efficacy.
- Simultaneous surface membrane modification occurs alongside potential DNA alterations, suggesting a key role in inactivation.
- Excited singlet molecular oxygen is implicated as a reactive intermediate.
Conclusions:
- Photosensitized reactions can damage proteins, lipids, and nucleic acids, but the precise correlation with cellular damage is unclear.
- The photodynamic process shows therapeutic potential, especially for malignant tumors, but requires enhanced selectivity.