A Computational Biology Approach to pH Selective Reactions in the Extracellular Fluid of Cancer Cells Based in the Gibbs Free Energy Minimization Approach

A common denominator of many cancer cells is that the extracellular pH e value is acidic (pH e <7) in contrast to the basic pH e values (>7) found in benign cells. The difference in the pH e values of cancer and benign cells has the potential to turn into a tool to develop chemical processes that will act against cancer cell proliferation selectively with a reduced impact in benign cells. We hypothesize that CaS nanostructures can selectively dissociate into Ca 2+ ions and sulfides in the acidic extracellular fluid of cancer cells but not in the basic microenvironment of benign cells. We have studied the reactions of CaS as a function of pH to simulate the different extracellular environments of cancer and benign cells using the Gibbs minimization approach in the Python environment. We found that the CaS readily dissociated in the acidic pH values to Ca 2+ ions and sulfides. The sulfides are distributed in pH sensitive species that include gaseous H 2 S, aqueous H 2 S, HS ‐ and S 2‐ ions. The results are consistent with experimental observations of H 2 S production from CaS as a function of pH performed in the laboratory bench. The results are discussed in the context of possible chemical process that take advantage of the acidic microenvironment in cancer tissues to selectively induce apoptosis in the cancer cells with no effect in the corresponding benign cells, reducing secondary effects associated with chemotherapies in the market today.