This study developed doxorubicin-loaded microneedles that melt and release the drug upon exposure to near-infrared light, combining chemotherapy and photothermal therapy. The microneedles contain photothermal nanoparticles that generate heat from near-infrared light to quickly melt the microneedles and release doxorubicin into punctured tissue in an on-demand, controlled manner. In vivo tests in mice showed the combined treatment had a synergistic effect, completely destroying tumors without weight loss or tumor recurrence, demonstrating these light-triggerable microneedles are a promising system for superficial cancer treatment.

1. Near-Infrared Light-Triggerable Microneedles
for Chemo-Photothermal Synergistic Therapy
Zhi-Wei Lin, Hao-An Chan, Mei-Chin Chen*
Department of Chemical Engineering
National Cheng Kung University, Taiwan
This study reports doxorubicin (DOX)-loaded near-infrared (NIR) light-triggerable microneedles (MNs) to combine chemotherapy
and photothermal therapy in one system. The MNs are consisted of biodegradable polycaprolactone and photothermal nanoparticles
(NPs). Upon exposure to NIR, MNs can quickly melt at 50 °C due to the heating of the encapsulated NPs and then release DOX
into the punctured tissue. Drug release can be controlled in an on-demand fashion, when LASER ON produced a steep increasing
in drug release, and LASER OFF had no obvious release over a long time. In vivo antitumor activity tests demonstrated the DOX-
loaed MNs with external NIR photothermal therapy significantly enhanced the therapeutic effect of cancer treatment. Compared
with chemotherapy or photothermal therapy alone, the combined treatment possessed a better therapeutic effect. These results
showed that the NIR-triggerable MNs may serve as a useful system for superficial cancer treatment.
▲Drug-loaded NIR triggerable MNs
▲ (a) Infrared images of MNs under NIR exposure
(b) Temperature profile of MNs for different On and Off cycles
▲Cumulative release of DOX from MNs under different
cycles of NIR laser exposure
▲ Pig cadaver skin under
different irradiation cycles
Melting process
of MNs in cadaver
skin after different
irradiation cycles:
(a) 3D reconstruction
from histological
sections
(b) Bright- field and
(c) Fluorencence
micrographs
▲Tumors on mice after various treatments
Complete elimination
▲(a) Normalized tumor volume and (b) Body weight curves after various treatments
We succefully developed DOX-loaded NIR light-
triggerable MNs to combine chemotherapy and
photothermal therapy in one system. The NIR
light triggered release test showed that the drug
release from the microneedles can be controlled
by the adjustment ofthe parameters of NIR light.
Combined treatment demonstrated a synergistic
effect, resulting in complete destruction of
tumors without weight loss and recurrence of
tumors.
[1] Chen MC, Ling MH, Lai KH and Pramudityo E
(2012) Biomacromolecules, 13:4022-4031
[2] You J, Zhang GD and Li C (2010) ACS Nano 4:1033-
1041.