Excimer laser-induced perturbation spectroscopy: an approach to biosensing

The development of new smart sensing methodologies that provide improved sensitivity and/or specificity for rapid and accurate biosensing is highly desirable for in situ and in vivo cancer screening and detection of biological pathogens. However, to date clinical applications of cancer sensing schemes have been for the most part limited by the large patient-to- patient variations in optical response (e.g. fluorescence or Raman signals), as well as by the large variation in background signal levels. A novel biosensing scheme is presented that is based on our recent research showing that the biological matrix may be altered by low intensity (i.e., below the ablation threshold) ultraviolet radiation (primarily 193 to 213 nm) such that the intrinsic fluorescence response is perturbed. Specifically, a sequential combination of optical probing (e.g. fluorescence emission), UV photochemical perturbation, and repeat optical probing is explored as a new spectral dimension based on difference spectroscopy. It is expected that the response is strongly coupled to the local biomolecular matrix. Because the same targeted material is optically probed both before and after perturbation with the UV light source, the resulting differential response may help mitigate variations in the absolute optical response. Preliminary data is presented using imaging mode and spectroscopy modes for several organic matrices as a proof of concept.