Zero-Potential No-Discharge APCI Combined With pH and Colorimetric Measurements Reveals a Protein-Dependent Change in Albumin Proton Affinity Under Quantum-Dot Patch Exposure.

The interaction between solvent, solute and physical phenomena (e.g., photon-emitting biomolecules) constitute one of the most fundamental, yet challenging, frontiers in modern biophysics and analytical chemistry. However, standard mass spectrometry instrumentation is often insufficient to yield useful data in this domain due to the solvent molecule bind alteration induced by high electric field presents in the usually employed ionization sources (e.g., Electrospray and Atmospheric Pressure Chemical Ionization). The challenge is to transport analyte ions from the condensed liquid phase into the high-vacuum gas phase of the mass analyzer with minimal voltages-induced loss of supramolecular structure or structural scrambling while preserving the solvent environment structure. In this work, we employed no-discharge ND-APCI that has been rigorously validated in regulatory environments operating in no voltage ionization conditions to investigate the interaction of Albumin and water molecule environment under the irradiation of photon emitted by means of quantum dots technology at different simultaneous wave lights (800 nm, 525 nm, 445 nm). The obtained results, in terms of albumin-solvent (water) interaction, are consistent with a protein-dependent change in the proton affinity of albumin and are corroborated by complementary pH and colorimetric (Coomassie) measurements; their possible mechanistic origin is discussed.