Lee Jae-Won, Kwak Ji Hye, Kim Juhee, Jang Yoon-Kwan, Han Joong Tark, Kim Tae-Jin, Hong Kyong-Soo, Jeong Hee Jin, Yang Imjeong H-S
Department of Physics, Pusan National University Busan 46241 South Korea
Nano Hybrid Technology Research Center, Creative and Fundamental Research Division, Korea Electrotechnology Research Institute (KERI) Changwon 51543 Republic of Korea
RSC Adv. 2024 Apr 10;14(16):11524-11532. doi: 10.1039/d4ra01113a. eCollection 2024 Apr 3.
Graphene oxide quantum dots (GOQDs) are promising candidates for biomedical applications since they have lower toxicity and higher biocompatibility than traditional semiconductor quantum dots. However, oxygen functional groups such as epoxy and hydroxyl groups usually induce nonradiative relaxation, which leads to GOQDs exhibiting nonemissive properties. For the enhancement of the emission efficiency of GOQDs, the number of nonradiative relaxation sites should be reduced. This paper reports the synthesis of highly luminescent reduced GOQDs prepared by liquid-phase photoreduction (LPP-rGOQDs). First, GOQDs was fabricated from single-walled carbon nanotubes through chlorate-based oxidation and separation after acoustic cavitation. Subsequently, LPP-rGOQDs were obtained by liquid-phase photoreduction of the GOQD suspension under intense pulsed light irradiation. Liquid-phase photoreduction selectively reduced epoxy groups present on the basal plane of GOQDs, and hydrogenated the basal plane without removal of carbonyl and carboxyl groups at the edges of the GOQDs. Such selective removal of oxidative functional groups was used to control the reduction degree of GOQDs, closely related to their optical properties. The optimized LPP-rGOQDs were bright blue in color and showed quantum yields up to about 19.7%, which was 10 times the quantum yield of GOQDs. Furthermore, the LPP-rGOQDs were utilized to image a human embryonic kidney (HEK293A), and a low cytotoxicity level and satisfactory cell imaging performance were observed.
氧化石墨烯量子点（GOQDs）是生物医学应用中很有前景的候选材料，因为它们比传统半导体量子点具有更低的毒性和更高的生物相容性。然而，环氧基和羟基等氧官能团通常会引发非辐射弛豫，这导致GOQDs表现出非发光特性。为了提高GOQDs的发射效率，应减少非辐射弛豫位点的数量。本文报道了通过液相光还原法制备的高发光性还原型GOQDs（LPP-rGOQDs）的合成。首先，通过基于氯酸盐的氧化和声学空化后的分离，由单壁碳纳米管制备出GOQDs。随后，在强脉冲光照射下，通过对GOQD悬浮液进行液相光还原得到LPP-rGOQDs。液相光还原选择性地还原了GOQDs基面存在的环氧基，并使基面氢化，同时未去除GOQDs边缘的羰基和羧基。这种对氧化官能团的选择性去除用于控制GOQDs的还原程度，这与它们的光学性质密切相关。优化后的LPP-rGOQDs呈亮蓝色，量子产率高达约19.7%，是GOQDs量子产率的10倍。此外，LPP-rGOQDs被用于对人胚肾细胞（HEK293A）进行成像，并观察到其细胞毒性水平较低且细胞成像性能良好。
