Time-Resolved Synchronous Fluorescence for Biomedical Diagnosis.

Xiaofeng Zhang,Tuan Vo-Dinh,Andrew Fales

doi:10.3390/s150921746

Abstract

This article presents our most recent advances in synchronous fluorescence (SF) methodology for biomedical diagnostics. The SF method is characterized by simultaneously scanning both the excitation and emission wavelengths while keeping a constant wavelength interval between them. Compared to conventional fluorescence spectroscopy, the SF method simplifies the emission spectrum while enabling greater selectivity, and has been successfully used to detect subtle differences in the fluorescence emission signatures of biochemical species in cells and tissues. The SF method can be used in imaging to analyze dysplastic cells in vitro and tissue in vivo. Based on the SF method, here we demonstrate the feasibility of a time-resolved synchronous fluorescence (TRSF) method, which incorporates the intrinsic fluorescent decay characteristics of the fluorophores. Our prototype TRSF system has clearly shown its advantage in spectro-temporal separation of the fluorophores that were otherwise difficult to spectrally separate in SF spectroscopy. We envision that our previously-tested SF imaging and the newly-developed TRSF methods will combine their proven diagnostic potentials in cancer diagnosis to further improve the efficacy of SF-based biomedical diagnostics.

Highlights

IntroductionA biopsy sample typically represents only a very limited area of the suspected tissue; and laboratory results using histopathology examinations are generally time-consuming
It has unique advantages compared to the conventional fixed-excitation fluorescence spectroscopy
Compared to the standard synchronous fluorescence (SF) method and the previous method, the proposed time-resolved synchronous fluorescence (TRSF) method better captures the full characteristics of fluorophores in complex samples

Summary

Introduction

A biopsy sample typically represents only a very limited area of the suspected tissue; and laboratory results using histopathology examinations are generally time-consuming. Fluorescence spectroscopy is a powerful technique that can be used to noninvasively analyze the fluorescent signatures of tissue. Autofluorescence of neoplastic and normal tissues using fixed-wavelength laser-induced fluorescence (LIF) have been investigated and used for cancer diagnosis in our laboratory as well as other laboratories [1,2,3,4,5,6,7]. Studies have demonstrated reasonably good specificity and sensitivity in sample classification, fixed-wavelength excitation typically produces fluorescence spectra exhibiting featureless profiles or broad-band peaks, which do not fully exploit the diagnostic potentials of fluorescence spectroscopy. The SF method has been coupled with multi-component analysis algorithms to obtain spectral signatures of environmental samples and to enhance selectivity in analyzing complex chemical and biological samples [9,10,11,12,13,14]

Methods

Results

Conclusion