Lasing with cell-endogenous fluorophores: parameters and conditions

Abstract

The notion of lasing with biologics has recently been realized and has rapidly developed with the collective objective of creating lasers in vivo. One major limitation of achieving this is the requirement of exogenous dyes and fluorescent materials. We thus investigate for the first time the possibility of lasing unlabelled cells, using just cell-endogenous fluorophores - the source of cell autofluorescence. In this work, we theoretically studied the lasing potential and efficiency of flavins and reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) using a dye lasing model based on coupled rate equations. Analytical solutions for one- and two-photon pumped system were used in multi-parameter studies. We found that at physiological conditions, the more abundant NAD(P)H can be lased with a cavity quality factor of 105. We then recommended the tuning of intersystem crossing to make the lasing of flavins feasible even at their low physiological concentrations. Under conditions of reduced intersystem crossing, we concluded that it is more practical to lase unlabelled cells using flavins, because lasing thresholds and cavity quality factors were both at least an order lower. We also note the higher threshold requirements and lower efficiencies of two-photon pumping, but recognize its potential for realizing lasing in vivo.

Identification of senescent cells in multipotent mesenchymal stromal cell cultures: Current methods and future directions

“…Despite the label-free and non-destructive advantage when using lipofusin fluorescence for cell senescence, there is still the challenge in acquiring autofluorescence due to its weak intensities. A potential workaround to this was recently explored in the method of cell lasing using endogenous fluorophores [120]. Through lasing, weak autofluorescence could potentially be amplified for easier detection.…”

FluoMALDI Microscopy: Matrix Co‐Crystallization Simultaneously Enhances Fluorescence and MALDI Imaging

“…Moreover, the FluoMALDI approach resulted in greater clarity of histological features, arising from the fluorescence enhancement of endogenous compounds including FAD and PPIX, among others, in tissue sections. [ 28 , 32 ] The observed fluorescence enhancement is caused by the co‐crystallization process, wherein analytes, including fluorophores, are embedded within micron‐sized crystals of MALDI matrices during the matrix deposition step. Both tissue fluorophores such as FAD, as well as exogenous fluorophores such as Rhodamine B, could incorporate into the matrix crystals.…”

FluoMALDI microscopy: matrix co-crystallization simultaneously enhances fluorescence and MALDI imaging

“…Hence, matrix deposition onto the sample allows for the enhanced detection of fluorescence signals in tissues and cells, allowing for faster fluorescence imaging with a lower threshold of detection, as demonstrated by FluoMALDI of Sharpie® marker drawings, various endogenous and exogenous fluorophores, and autofluorescence from cryosections of mouse brains and kidneys. Moreover, the FluoMALDI approach resulted in greater clarity of histological features, arising from the fluorescence enhancement of endogenous compounds including FAD and PPIX, among others, in tissue sections 38,40 . The observed fluorescence enhancement is caused by the co-crystallization process, wherein analytes, including fluorophores, are embedded within micron-sized crystals of MALDI matrices during the matrix deposition step.…”