Thiolated-2-methacryloyloxyethyl phosphorylcholine protected silver nanoparticles as novel photo-induced cell-killing agents

Abstract

Event Abstract Back to Event Thiolated-2-methacryloyloxyethyl phosphorylcholine protected silver nanoparticles as novel photo-induced cell-killing agents Arunee Sangsuwan1, Hideya Kawasaki2, 3 and Yasuhiko Iwasaki2, 3 1 Kansai university, Graduate School of Science and Engineering, Japan 2 Kansai university, Faculty of Chemistry, Materials and Bioengineering, Japan 3 Kansai university, ORDIST, Japan Introduction: The usefulness of silver nanoparticles is well known due to their various advantages and extensive applications. Thus, the synthesis of metal nanoparticles with predictable and well-defined structures is of interest in medical and diagnostic applications[1]. However, AgNPs are of limited use in medicine because of their toxicity, which may damage healthy surrounding tissue. Research is continuously being conducted to resolve this issue. In this study, thiolated-2-methacryloyloxyethyl phosphorylcholine (MPC-SH) protected silver nanoparticles (MPC-AgNPs) were prepared as cell-killing agents under UV irradiation. The viability of cells in contact with MPC-AgNPs was relatively high and MPC-AgNPs also exhibit a cell-killing effect under UV irradiation. Materials and Methods: Thiol-terminated MPC (MPC-SH) was synthesized from the modified method of Goda and co-workers[2]. MPC-SH was mixed with silver nitrate and formic acid in deionized water. The solution was stirred at 70 °C for 3 hours. The reaction mixture was dialyzed to purify MPC-AgNPs. MPC-AgNPs were then centrifuged at 6,000 rpm for 15 minutes and lyophilized. The cytotoxicity of MPC-AgNPs was detemined by using HeLa cells and half maximal inhibitory concentration (LC50) of the nanoparticles was determined. Moreover, photo-induced toxicity of MPC-AgNPs was investigated under 356 nm photo irradiation. Results: The MPC-AgNPs can be prepared via strong thiolmetal coordination. Immobilized MPC on AgNPs was confirmed by XPS and IR analyses. The presence of AgNPs in the form of Ag0 was verified by XRD, and the average diameter of particles was determined as 13.4 ± 2.2 nm by TEM and 18.4 nm (PDI 0.18) by DLS. MPC-AgNPs showed toxicity at concentrations of 5 μg/mL or higher as shown in Fig.1. The LC50 of MPC-AgNPs was about 14.7 μg/mL, which shows a greater biocompatibility than AgNO3, bare AgNPs, chitosan-coated AgNTs, and polyvinylpyrrolidone-coated AgNPs, as determined by previous studies[3],[4]. Photo-induced toxicity of MPC-AgNPs on HeLa cells significantly decreased the cell viability to about 50% in a particle concentration at 0.5 μg/mL, and at a higher concentration of 1 μg/mL, the HeLa cells died completely from the photo-induced toxicity of MPC-AgNPs as shown in Fig.2. Discussion: MPC improves both biocompatibility and dispersity of nanoparticles. MPC-AgNPs used in our research were small size particles, which are conducive to high cytotoxicity, in accordance with the results of previous studies. In addition, the particles exhibit a highly potent cell-killing effect under UV irradiation; they lost SPR after irradiation, resulting in a decreasing SPR band and particle size, as measured by UV-visible spectrophotometry and DLS, respectively. Conclusion: The present study demonstrates that MPC-AgNPs can be prepared via strong thiolmetal coordination and the average diameter of particles was determined as 13.4 ± 2.2 nm by TEM and 18.4 nm (PDI 0.18) by DLS. MPC improves both biocompatibility and dispersity of nanoparticles. Our findings suggest that the cell death mechanism is possible because particles lose areas of their surface and particles losing MPC are toxic. Finally, biocompatible MPC-AgNPs are exhibited after activation by light, which makes them potentially useful as photo-induced cell-killing agents. Grant-in-Aid for Scientific Research on Innovative Areas ‘‘Nanomedicine Molecular Science’’ (No. 2306) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan.