Proton-Functionalized Two-Dimensional Graphitic Carbon Nitride Nanosheet: An Excellent Metal-/Label-Free Biosensing Platform
Proton-Functionalized Two-Dimensional Graphitic Carbon Nitride Nanosheet: An Excellent Metal-/Label-Free Biosensing Platform
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DOI：
10.1002/smll.201303827
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发表时间：
2014-06-25
期刊：
影响因子：
13.3
通讯作者：
Qiao, Shi Zhang
中科院分区：
文献类型：
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作者：
Ma, Tian Yi;Tang, Youhong;Qiao, Shi Zhang
超薄石墨氮化碳（g-C3 N4）纳米片由于其有趣的二维石墨烯样结构和独特的物理化学性质，近年来引起了人们的极大关注。在这里，开发了一种新的方法来制备，第一次，质子功能化的big-C3 N4纳米片的大块g-C3 N4在酸性条件下的超声剥离。这种方法不仅将剥离时间从10 h以上缩短到2 h，而且赋予纳米片正电荷。除了保留g-C3 N4的性质外，所获得的厚度为2-4 nm的纳米片（即，6-12原子单分子层）还表现出305 m2/g（-1）的大比表面积、增强的荧光强度和优异的水分散稳定性，这是由于它们的表面质子化和水分散形态。良好分散的质子化g-C3 N4纳米片能够与带负电荷的肝素相互作用，这导致g-C3 N4荧光淬灭。建立了一种基于质子化g-C3 N4纳米片的高灵敏、高选择性肝素传感平台。这种无金属和荧光团标记的系统可以达到18 ng mL（-1）的最低肝素检测限。
Ultrathin graphitic carbon nitride (g-C3N4) nanosheets, due to their interesting two-dimensional graphene-like structure and unique physicochemical properties, have attracted great research attention recently. Here, a new approach is developed to prepare, for the first time, proton-functionalized ultrathin g-C3N4 nanosheets by sonication-exfoliation of bulk g-C3N4 under an acid condition. This method not only reduces the exfoliation time from more than 10 h to 2 h, but also endows the nanosheets with positive charges. Besides retaining the properties of g-C3N4, the obtained nanosheets with the thickness of 2-4 nm (i.e., 6-12 atomic monolayers) also exhibit large specific surface area of 305 m(2) g(-1), enhanced fluorescence intensity, and excellent water dispersion stability due to their surface protonation and ultrathin morphology. The well-dispersed protonated g-C3N4 nanosheets are able to interact with negatively charged heparin, which results in the quenching of g-C3N4 fluorescence. A highly sensitive and highly selective heparin sensing platform based on protonated g-C3N4 nanosheets is established. This metal-free and fluorophore label-free system can reach the lowest heparin detection limit of 18 ng mL(-1).