Porous Covalent Triazine Polymer as a Potential Nanocargo for Cancer Therapy and

Imaging Arunkumar Rengaraj,aѱ Pillaiyar Puthiaraj,bѱ Yuvaraj Haldorai,c Nam Su Heo,a Seung-Kyu Hwang,a Soonjo

Kwon,d Wha-Seung Ahn,b* and Yun Suk Huha*

aDepartment of Biological Engineering, Biohybrid Systems Research Center (BSRC), Inha University, Incheon, 402-751,

Republic of Korea.bDepartment of Chemistry and Chemical Engineering, Inha University, Incheon 402-751, Republic of Korea.cDepartment of Energy and Materials Engineering, Dongguk University-Seoul, Seoul ,100-715, Republic of Korea.dDepartment of Biological Engineering, Integrated Tissue Culture Laboratory, Inha University, Incheon, 402-751, Re-

public of Korea.

Fax: +82-32-872-4046; Email:yunsuk.huh@inha.ac.kr

Ѱ–These two authors contributed equally

Abstract

A microporous covalent triazine polymer (CTP) network with a high surface area was synthesized via the Friedel-Crafts reaction

for anticancer drug delivery and controlled release. The CTP is transformed to the nanoscale region by intense ultasonication fol-

lowed by filtration to yield nanoscale CTP (NCTP) with excellent dispersibility in physiological solution while maintaining its

chemical structure and the porosity of the material. An anti-cancer drug, doxorubicin (DOX), is loaded onto the NCTP through

simple physisorption by hydrophobic and π–π interactions, and its release can be controlled at acidic and neutral pH. The NCTP

did not show practical toxicity to cancer and normal cells, but the NCTP-DOX complex showed high efficacy at killing both types

of cells in-vitro. The prolonged drug release (over 50h) from the NCTP-DOX at neutral and acidic pH values was demonstrated.

The in-vitro cell imaging results indicate that NCTP has good potential for bio-imaging. The cellular senescence and potency of

NCTP was confirmed by the expression of senescence associated marker proteins p53 and p21. These results suggest that NCTP

can be used as a new platform for imaging and drug delivery, which may find potential applications in diagnosis and therapy.

Keywords: Covalent triazine polymer, Porous material, Fluorescence, Biocompatible, Drug delivery

Scheme 1 Strategy employed to synthesize NCTP-DOX.

Figure 1 (a) FTIR, (b) BET, (c) zeta potential, and (d) PL

analysis of NCTP.

Figure 2 SEM and TEM analysis of CTP (a, d) before sonication, (b, e) after sonication, and (c, f) after filtration.

Figure 3 Cytotoxic study of the NCTP (a) COS-7 and (b) HeLa

cells.

Figure 4 (a) Loading efficiency of DOX, (b) pH induced

controlled drug release, and (c) mechanism for pH induced drug

release.

Figure 5 (a) Optical microscopic images, (b) confocal fluorescence microscopy images, and (c) overlay of HeLa cells

before (i) and after (ii, iii) being incubated for 24 h with NCTP and NCTP-DOX.

Figure 6 Relative cell viability of (a) COS-7 and (b) HeLa cells treated with free DOX and NCTP-DOX at various

concentrations, and (c) Bio-TEM images of (i) control and (ii) NCTP-DOX treated HeLa cells after 6 h.

Figure 7 SA β-galactosidase assay for NCTP-DOX (a) before staining, (b) after staining and protein expression of (c)

DOX and (d) NCTP-DOX on HeLa cells.

In summary, we successfully synthesized NCTP and used it as both a potential

photosensitizer and pH-responsive nanocarrier for cancer therapy and imaging. NCTP with

pH-dependent drug releasing properties were suitable for drug delivery over cancer cells.

The NCTP-DOX exhibited a higher cytotoxic effect on cancer cells than free DOX and

induced strong senescence at lower concentration. Of particular significance, the NCTP–

DOX complex features a DOX-loading capacity of 200 mg/g due to its high specific surface

area, π-π stacking and hydrophobic interaction. Our results indicate the potential for use of

NCTP as a low-toxic and biocompatible 2D nanomaterial for cancer diagnosis and therapy.