4 Notes
1. Low the electric pulses voltage. Like what occurs in many
micro/nanofluidic electroporation proof-of-concepts [5–7],
micropillars in MAE also help low the electric pulse voltage
with their microscale distance between two electrodes. For
comparison purpose, electroporation tests using both a commercial 2-mm cuvette (denoted as “BE”) and another configuration with two closely placed plain electrodes but no
micropillar pattern (denoted as “Au Plain Plate”) are carried
out. With only difference from the gap size of the two parallel
electrodes and consequence pulse voltage (while maintain the
same field strength of 625 V/cm), the transfection efficiency
with two closely placed plain plate electrodes (43.6 Æ 1.6% for
K562 cells and 44.1 Æ 1.8% for 3T3 cells) is generally much
better than that from BE (K562: 25.7 Æ 1.8%, 3T3:
25.4 Æ 3.6%) [8]. Such results suggest that the improvement
of MAE (K562: 70.3 Æ 2.5%, 3T3: 65.1 Æ 3.7%) is indeed
attributed to both the micropillar features and the closely
placed electrode configuration. Although the high-voltage
induced apoptosis issues are largely mitigated with its much
lower pulse voltage (10 V), the electrochemical hydrolysis of
water is not eliminated completely in MAE. As the cell suspension is squeezed in the narrow gap between electrodes in MAE,
more cells are brought close to the micropillar electrode and
the electrochemical hydrolysis associated negative impact on
0%
20%
40%
60%
80%
100%
120%
Lcu
GPF
plasmid
BE, pDNA+ 5pmol siRNA MAE, pDNA+ 5pmol RNA
(b)
(a)
0
20
40
60
80
100
K5623T3A549
Transfection Efficiency
2‐um Array 6‐um Array
**
**
**
***
**
Fig. 5 (a) Comparison of MAE electroporation pGFP transfection enhancement with different micropillar size
(6-μm micropillar array and 2-μm micropillar array); (b) Enhancement on siRNA delivery in 2-μm MAE in the
downregulation of both GFP and luciferase expression level in K562 when cotransfecting pDNA and its
corresponding siRNA. Triple duplicates with (∗∗) represents p < 0.01, (∗∗∗) represents p < 0.005
10
Xuan Liu et al.
1. Low the electric pulses voltage. Like what occurs in many
micro/nanofluidic electroporation proof-of-concepts [5–7],
micropillars in MAE also help low the electric pulse voltage
with their microscale distance between two electrodes. For
comparison purpose, electroporation tests using both a commercial 2-mm cuvette (denoted as “BE”) and another configuration with two closely placed plain electrodes but no
micropillar pattern (denoted as “Au Plain Plate”) are carried
out. With only difference from the gap size of the two parallel
electrodes and consequence pulse voltage (while maintain the
same field strength of 625 V/cm), the transfection efficiency
with two closely placed plain plate electrodes (43.6 Æ 1.6% for
K562 cells and 44.1 Æ 1.8% for 3T3 cells) is generally much
better than that from BE (K562: 25.7 Æ 1.8%, 3T3:
25.4 Æ 3.6%) [8]. Such results suggest that the improvement
of MAE (K562: 70.3 Æ 2.5%, 3T3: 65.1 Æ 3.7%) is indeed
attributed to both the micropillar features and the closely
placed electrode configuration. Although the high-voltage
induced apoptosis issues are largely mitigated with its much
lower pulse voltage (10 V), the electrochemical hydrolysis of
water is not eliminated completely in MAE. As the cell suspension is squeezed in the narrow gap between electrodes in MAE,
more cells are brought close to the micropillar electrode and
the electrochemical hydrolysis associated negative impact on
0%
20%
40%
60%
80%
100%
120%
Lcu
GPF
plasmid
BE, pDNA+ 5pmol siRNA MAE, pDNA+ 5pmol RNA
(b)
(a)
0
20
40
60
80
100
K5623T3A549
Transfection Efficiency
2‐um Array 6‐um Array
**
**
**
***
**
Fig. 5 (a) Comparison of MAE electroporation pGFP transfection enhancement with different micropillar size
(6-μm micropillar array and 2-μm micropillar array); (b) Enhancement on siRNA delivery in 2-μm MAE in the
downregulation of both GFP and luciferase expression level in K562 when cotransfecting pDNA and its
corresponding siRNA. Triple duplicates with (∗∗) represents p < 0.01, (∗∗∗) represents p < 0.005
10
Xuan Liu et al.