石墨烯量子点荧光增强及pH响应特性研究

Graphene quantum dots fluorescence enhancement and pH response characteristics

本文详细研究了交联剂1-乙基-3-(3-二甲基氨基丙基)碳二亚胺盐酸盐(EDC)对石墨烯量子点(GQDs)光学性质的影响及原因。采用水热法制备了GQDs,并与EDC反应得到GQDs/EDC复合物,对GQDs和GQDs/EDC的光谱特性进行研究。使用PBS溶液以及人工胃液样品,研究pH对GQDs/EDC荧光影响规律及作用机理。实验结果表明:GQDs表面缺陷被EDC钝化,使得GQDs的荧光在小于1 min内迅速增强,并在5~20 min内保持稳定;相比单独GQDs,GQDs/EDC的荧光强度显著提升约264倍;pH响应实验表明,在pH值为1.75~4.01及4.01~9.28范围内,GQDs/EDC具有荧光和吸收强度线性响应规律。生物兼容性表明,在25~300μg/mL样品浓度下,人乳腺癌细胞存活率均大于80%;同时,对人工胃液pH具有较高的检测准确性,其相对标准偏差RSD≤1.10%。EDC介导的荧光增强,使GQDs在检测、传感、成像等领域更具优势。同时,GQDs/EDC灵敏的pH响应特性使其在pH值检测应用中具有良好前景。

In this paper,the effect of the cross-linking agent 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride(EDC)on the optical properties of graphene quantum dots(GQDs)and the reasons are investigated in detail.GQDs were prepared by a hydrothermal method and reacted with EDC to obtain GQDs/EDC composites.The spectral properties of GQDs and GQDs/EDC were investigated.The effect of pH on the fluorescence of GQDs/EDC and its mechanism were investigated using PBS solution and artificial gastric juice samples.The experimental results show that EDC passives the surface defects of GQDs,making the fluorescence of GQDs increase rapidly in<1 min time and remain stable up to 20 min.Under different EDC contents the fluorescence intensity of GQDs/EDC is significantly enhanced by about 264 times compared to GQDs alone.The pH response experiments shows that GQDs/EDC had a linear response pattern of fluorescence and absorption intensity in the pH range of 1.75−4.01 and 4.01−9.28.Biocompatibility showed that the cell viability of human breast cancer cells was greater than 80%at sample concentrations of 25−300μg/mL and remained at 74%even at high concentrations of 500μg/mL;Finally,the detection of artificial gastric pH has high accuracy with relative standard deviation RSD≤1.10%.The EDC-mediated fluorescence enhancement makes GQDs more advantageous in the fields of detection,sensing and imaging.Besides,the sensitive pH response characteristics of GQDs/EDC provide a good prospect for pH detection applications.