@ARTICLE{10.21494/ISTE.OP.2023.0915, 

TITLE={Photo-Dynamic Therapy - between modeling and experimentation - the convergence(s) of physicists, chemists, biologists, oncologists, engineers or when diffusional modeling finds its limits…}, 
  
AUTHOR={Jean-Claude André, Céline Frochot, }, 
	
JOURNAL={Entropy: Thermodynamics – Energy – Environment – Economy }, 
	
VOLUME={3}, 

NUMBER={Issue 2}, 
	
YEAR={2023}, 

URL={https://www.openscience.fr/Photo-Dynamic-Therapy-between-modeling-and-experimentation-the-convergence-s-of}, 
	
DOI={10.21494/ISTE.OP.2023.0915}, 
	
ISSN={2634-1476}, 
	
ABSTRACT={Photo-dynamic therapy (PDT) consists in using light to electronically excite a photoactivatable molecule (the photosensitizer, PS) previously injected into the human body. This excited molecule will react with oxygen present in the biological environment to lead to the formation of reactive oxygen species (ROS) which will preferentially destroy cancer cells. Current research is focused on the development of more selective PS that target receptors over-expressed on cancer cell membranes for example. Another way to target is the use of Photo-Molecular beacons (PMB). They are classically composed of an A acceptor and a D donor, linked by a linkage sensitive to an endogenous stimulus. In the initial state, the acceptor and the donor are kept sufficiently close to allow an energy transfer from D* to A (electronically excited D) by preventing the production of ROS. Based on this principle, it is possible to restrict the PDT effect to the immediate vicinity of malignant cells when the distance D-A increases. Indeed, it is possible to use a link sensitive to enzymes such as certain metalloproteinases MMP overexpressed in tumor areas. The action of the MMPs leads to the destruction of the link, thus releasing D which, under illumination, can produce ROS. D* is usually fluorescent and it is possible to follow its temporal evolution by molecular emission spectroscopy. To try to understand the reaction mechanism of D* linked by a spacer arm to A (DBA), the reverse situation is studied. Several models of transport-reactivity coupling have been developed leading to expressions for the reaction rate constant of the form k(t) = a + b.t1/2 where t is time and a and b are two experimental parameters. However, when we examine the behavior of synthesized D*BA couples, it is not possible to find the parameters a and b with a physical basis. Different hypotheses are proposed to try to understand the differences between modeling and experiments. An analysis of the points of view of the other disciplines involved in this approach to cancer treatment is also proposed.}}