Development of a Triplet–Triplet Absorption Ruler: DNA- and Chromatin-Mediated Drug Molecule Release from a Nanosurface

Triplet–triplet (T–T) absorption spectroscopy has been used successfully as a molecular ruler to understand the actual release process of sanguinarine as a drug molecule from a gold nanoparticle surface in the presence of cell components, that is, DNA and chromatin. The obtained results have been verified by fluorescence and surface-enhanced Raman spectroscopy (SERS), and a plausible explanation has been put forward to describe the underestimation and overestimation of the percentage (%) of the release of drug molecules measured by fluorescence- and SERS-based techniques, respectively, over the highlighted T–T absorption spectroscopy. Because of the intrinsic nature of absorption, the reported T–T absorption spectroscopic assay overpowers fluorescence- and SERS-based assays, which are limited by the long-range interaction and nonlinear dependence of the concentration of analytes, respectively.