Fluorescence Signal Amplification for Ultrasensitive DNA Detection

Abstract

Ultrasensitive and reliable DNA detection tools are currently needed for the diagnostic of infectious and genetic diseases. To achieve the required sensitivity, one can amplify either the target DNA or the signal generated by each target molecule detected. Since enzymatic amplification of DNA is prone to contamination or inhibition, sensors that can benefit from signal amplification are usually more robust. Several approaches have been developed to obtain an amplification of the fluorescence signal generated by some biosensors upon DNA detection. Some among them feature the use of conjugated polymers as biosensors; due to their collective system response, they offer an amplification of the signal as compared to the response of individual monomers. Other approaches feature the use of efficient Forster energy transfer schemes. The use of fluorophore encapsulation, to increase the number of fluorophores reporting a detection event and to protect them from quenching species, can also be used to obtain an amplified fluorescence signal. The purpose of this review is to point out and discuss how these different methods achieve the observed fluorescence signal amplification, in order to relate them to what is known about fluorescence emission and energy transfer.