Stable fluorescence conjugation of ZnO nanoparticles and their size dependent cellular uptake.
We evaluated size dependent cellular uptake of ZnO nanoparticles utilizing stably introduced Cy5.5, which emits long-wavelength fluorescence. Through (3-aminopropyl)triethoxysilane modification, ZnO nanoparticles of different sizes (20 and 70nm) were functionalized with amine moiety, which was further reacted with Cy5.5-N-hydroxylsuccinimide ester to make covalently conjugated Cy5.5 dye on ZnO nanoparticles. Field emission-scanning electron microscopic images revealed that average particle size as well as particle morphology of ZnO nanoparticles were not altered by Cy5.5 conjugation. Zeta potential measurement confirmed that the positive surface charge of ZnO nanoparticles was well preserved after successive conjugation reactions. Based on infrared, ultraviolet-visible light and photoluminescence spectroscopies, we verify that the Cy5.5 was stably introduced to ZnO nanoparticles without serious aggregation. Surface conjugated Cy5.5 showed high stability in deionized water, phosphate buffered saline and cell culture medium, showing less than 2% of release during 85h. Confocal microscopy and fluorescence-activated cell sorting analysis demonstrated that smaller ZnO nanoparticles were more taken up in greater quantities by HaCaT cells. Moreover, systematic study on cellular uptake pathway showed that smaller ZnO nanoparticles were internalized into cells mainly by clathrin-mediated endocytosis, while larger ZnO nanoparticles entered cells via several pathways.
Department of Chemistry and Medical Chemistry, College of Science and Technology, Yonsei University, 1 Yonseidaegil, Wonju, Gangwondo 26493, Republic of Korea; Seoul Institute, National Forensic Service, 139, Jiyang-ro, Yangcheon-gu, Seoul 08036, Republic of Korea.
Kyoung-Min
KM
Kim
Department of Chemistry and Medical Chemistry, College of Science and Technology, Yonsei University, 1 Yonseidaegil, Wonju, Gangwondo 26493, Republic of Korea.
Min-Kyu
MK
Kim
Department of Food Science and Technology, Seoul Women's University, 621 Hwarang-ro, Nowon-gu, Seoul 01797, Republic of Korea.
Hee-Jeong
HJ
Paek
Department of Food Science and Technology, Seoul Women's University, 621 Hwarang-ro, Nowon-gu, Seoul 01797, Republic of Korea. Electronic address: sjchoi@swu.ac.kr.
Soo-Jin
SJ
Choi
Department of Chemistry and Medical Chemistry, College of Science and Technology, Yonsei University, 1 Yonseidaegil, Wonju, Gangwondo 26493, Republic of Korea. Electronic address: jaemin.oh@yonsei.ac.kr.
Jae-Min
JM
Oh
D002460:Cell Line; D005453:Fluorescence; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry*; D018613:Microscopy, Confocal; D014466:Ultraviolet Rays; D015034:Zinc Oxide / Q000737:chemistry*
D015034:Zinc Oxide
Cellular uptake; Cy5.5 conjugation; Fluorescent stability; Particle size; Physico-chemical property of ZnO; Zinc oxide nanoparticles