Visual and fluorometric determination of telomerase activity
by using a cationic conjugated polymer and fluorescence
resonance energy transfer
Received: 27 March 2017 /Accepted: 1 June 2017 /Published online: 21 June 2017
Springer-Verlag GmbH Austria 2017
Abstract The detection of telomerase activity is important in
cancer diagnosis and in screening for anti-cancer drugs. This
work describes a fluorometric method for the determination of
telomerase activity by using a cationic conjugated polymer
(CCP). Telomerase substrate primers were labelled with car-
boxyfluorescein (FAM-TS) which display weak electrostatic
interactions with the CCP. Hence, fluorescence resonance en-
ergy transfer (FRET) from photoexcited CCP to FAM is weak.
However, in the presence of telomerase, telomeric repeats
(TTAGGG)x were elongated to the 3′-end of FAM-TS to form
multiple G-quadruplexes in the presence of potassium ion
). These G-quadruplexes trigger strong electrical interac-
tion between the condensed G-quadruplexes and the CCP, and
this results in closer proximity and in more efficient FRET. As
a result, strong green fluorescence (peaking at 527 nm) is
emitted by FAM. Fluorescence can be visually observed under
a UV lamp and be used to quantify the activity of telomerase
by using a fluorometer. The assay was applied to the determi-
nation of HeLa cells in the 30 to 1000 cells per mL range, with
a detection limit as low as 5 cells per mL (at an S/N ratio of 3).
The method was applied to the detection of various cancer cell
lines in human urine samples. The method is simple, sensitive,
selective and accurate.
Human telomeres are used in clinical diagnosis related to ge-
nome stability, cancer, and aging . Telomerase activation
has been observed in ~90% of all human tumors, while it is
usually absent from or at very low levels in most somatic cells.
Thus, the sensitive and simple detection of telomerase activity
have considerable significance both for diagnosis and the
screening of anti-cancer drugs.
A number of techniques to measure telomerase activ-
ity has been developed. The telomeric repeat amplifica-
tion protocol (TRAP) that based on polymerase chain
reaction (PCR) is the most commonly applied method
[2, 3]. Other methods include colorimetry [4, 5], electro
analysis [6, 7], fluorescence [8, 9], and surface plasmon
resonance [10, 11]. Besides, exponential isothermal am-
plification [12, 13], various DNAzyme methods [4, 13],
and exonuclease-assisted target recycling [2, 12]were
used to improve the detection sensitivity and efficiency.
Among these methods, due to its high sensitivity and
unique feature of imaging [14, 15] fluorescence is su-
perior to other methods.
Electronic supplementary material The online version of this article
(doi:10.1007/s00604-017-2362-5) contains supplementary material,
which is available to authorized users.
* Wei Wei
Jiangsu Engineering Laboratory of Smart Carbon-Rich Materials and
Device, School of Chemistry and Chemical Engineering, Southeast
University, Nanjing 211189, China
College of Food Science and Technology, Henan University of
Technology, Zhengzhou 450001, China
Microchim Acta (2017) 184:3453–3460