compared to as-prepared and p-DNA-immobilized P3MT(DBSA) NWs, as shown in
the right image of Fig. 25a.
Figure 25b shows 3D LCM PL images of the P3MT(DBSA), P3MT(DBSA)/
p-DNA, and P3MT(DBSA)/p-DNA + t-DNA single NWs. The average voltages of
the LCM PL intensities for the as-prepared P3MT(DBSA), P3MT(DBSA)/p-DNA,
and P3MT(DBSA)/p-DNA + t-DNA single NWs were 11 (Æ2), 10 (Æ1), and 61
(Æ3) mV, respectively. The LCM PL intensity of the functionalized P3MT
(DBSA)/p-DNA + t-DNA single NW was about six times higher than that of the
as-prepared P3MT(DBSA) single NW.
The LCM PL spectra of the single NWs were compared, as shown in Fig. 25c. The
main PL peak of the as-prepared single NW was observed at ~554 nm. When coupled
with p-DNA, the main PL peak was red-shifted to ~640 nm and its intensity
decreased slightly. Upon hybridization of the P3MT(DBSA)/p-DNA NW with
t-DNA, the maximum intensity of the LCM PL peak was enhanced up to about six
times compared with that of the as-prepared NW. The change in the luminescence
characteristics of P3MT(DBSA) NWs was also studied using 1-mer mismatched
t-DNAs. When the p-DNAs were coupled with the 1-mer mismatched t-DNAs
(100 nM), the LCM PL intensity of the P3MT(DBSA)/p-DNA + t-DNA (1-mer
mismatch) single NW was much lower than that in the perfect match case, as
shown in Fig. 25c. The significant increase in the PL intensity of the P3MT
(DBSA)/p-DNA + t-DNA single NW might be due to the dopant-mediated energy
transfer effect in the fluorescence chain reaction between the t-DNA and lightemitting P3MT chains. These results highlight the possibility for nanoscale optical
detection of DNA without a fluorescent dye using a light-emitting P3MT(DBSA)
single NW on the basis of the change in the luminescence color and intensity.
The nanoscale luminescence characteristics of a single P3MT NW with a different
dopant, namely, tetrabutylammonium trifluoromethane sulfuric acid (TBACF 3 SO 3 ),
and the DNA-functionalized states were examined to reconfirm the feasibility of
dopant-mediated DNA detection. Weak green light emission was observed for the
P3MT(TBACF 3 SO 3 ) single NW (left image of Fig. 26a). When the NWs were
coupled with p-DNA, the color changed from green to red with a slightly decrease
in luminescence intensity, as shown in the inset of the left image of Fig. 26a. The
luminescence color CCD image of a P3MT(TBACF 3 SO 3 )/p-DNA + t-DNA single
NW showed significantly brighter red light emission than the single NW without
t-DNA (right image of Fig. 26a). The novel PL enhancement of P3MT(TBACF 3 SO 3 )
single NWs through hybridization with t-DNA was examined as a function of the
t-DNA concentration from 100 aM to 100 nM, as shown in Fig. 26b. As the
concentration of t-DNA increased, the LCM PL intensity of the single NW also
increased, suggesting that effective energy transfer occurs in the fluorescence chain
reaction between the light-emitting NW and t-DNAs. The maximum intensity of the
LCM PL peak and its integrated area for a single NW hybridized with complementary t-DNA (100 nM) increased by a maximum of approximately 30-fold compared
with that of the as-prepared and p-DNA-functionalized NWs. In addition, the LCM
PL intensity of the NW hybridized with t-DNA at a concentration of 100 aM
increased seven to eightfold compared with that of the NW without t-DNA.
Synthesis, Characteristics, and Applications of Intrinsically Light-Emitting. . .
235
the right image of Fig. 25a.
Figure 25b shows 3D LCM PL images of the P3MT(DBSA), P3MT(DBSA)/
p-DNA, and P3MT(DBSA)/p-DNA + t-DNA single NWs. The average voltages of
the LCM PL intensities for the as-prepared P3MT(DBSA), P3MT(DBSA)/p-DNA,
and P3MT(DBSA)/p-DNA + t-DNA single NWs were 11 (Æ2), 10 (Æ1), and 61
(Æ3) mV, respectively. The LCM PL intensity of the functionalized P3MT
(DBSA)/p-DNA + t-DNA single NW was about six times higher than that of the
as-prepared P3MT(DBSA) single NW.
The LCM PL spectra of the single NWs were compared, as shown in Fig. 25c. The
main PL peak of the as-prepared single NW was observed at ~554 nm. When coupled
with p-DNA, the main PL peak was red-shifted to ~640 nm and its intensity
decreased slightly. Upon hybridization of the P3MT(DBSA)/p-DNA NW with
t-DNA, the maximum intensity of the LCM PL peak was enhanced up to about six
times compared with that of the as-prepared NW. The change in the luminescence
characteristics of P3MT(DBSA) NWs was also studied using 1-mer mismatched
t-DNAs. When the p-DNAs were coupled with the 1-mer mismatched t-DNAs
(100 nM), the LCM PL intensity of the P3MT(DBSA)/p-DNA + t-DNA (1-mer
mismatch) single NW was much lower than that in the perfect match case, as
shown in Fig. 25c. The significant increase in the PL intensity of the P3MT
(DBSA)/p-DNA + t-DNA single NW might be due to the dopant-mediated energy
transfer effect in the fluorescence chain reaction between the t-DNA and lightemitting P3MT chains. These results highlight the possibility for nanoscale optical
detection of DNA without a fluorescent dye using a light-emitting P3MT(DBSA)
single NW on the basis of the change in the luminescence color and intensity.
The nanoscale luminescence characteristics of a single P3MT NW with a different
dopant, namely, tetrabutylammonium trifluoromethane sulfuric acid (TBACF 3 SO 3 ),
and the DNA-functionalized states were examined to reconfirm the feasibility of
dopant-mediated DNA detection. Weak green light emission was observed for the
P3MT(TBACF 3 SO 3 ) single NW (left image of Fig. 26a). When the NWs were
coupled with p-DNA, the color changed from green to red with a slightly decrease
in luminescence intensity, as shown in the inset of the left image of Fig. 26a. The
luminescence color CCD image of a P3MT(TBACF 3 SO 3 )/p-DNA + t-DNA single
NW showed significantly brighter red light emission than the single NW without
t-DNA (right image of Fig. 26a). The novel PL enhancement of P3MT(TBACF 3 SO 3 )
single NWs through hybridization with t-DNA was examined as a function of the
t-DNA concentration from 100 aM to 100 nM, as shown in Fig. 26b. As the
concentration of t-DNA increased, the LCM PL intensity of the single NW also
increased, suggesting that effective energy transfer occurs in the fluorescence chain
reaction between the light-emitting NW and t-DNAs. The maximum intensity of the
LCM PL peak and its integrated area for a single NW hybridized with complementary t-DNA (100 nM) increased by a maximum of approximately 30-fold compared
with that of the as-prepared and p-DNA-functionalized NWs. In addition, the LCM
PL intensity of the NW hybridized with t-DNA at a concentration of 100 aM
increased seven to eightfold compared with that of the NW without t-DNA.
Synthesis, Characteristics, and Applications of Intrinsically Light-Emitting. . .
235