The rational design of environmentally sensitive small molecule fluorophores with superior photophysical properties is critical for fluorimetry based biosensing. Herein, we have developed a new donor-acceptor fluorophore for quantitative detection of Human Serum Albumin (HSA) in aqueous samples. The fluorophore was easily prepared by Knoevenagel condensation, and showed excellent photophysical properties and positive solvatochromism. The design of the fluorophore was based on a nitrogen donor—π-conjugation—nitrile acceptors (D—π—A) to preserve efficient intramolecular charge transfer and long-wavelength emission. The fluorophore showed remarkable “turn-on” fluorescence in presence of HSA, which led to quantitative determination of the protein in aqueous buffer samples. Structure and electronic properties of the fluorophore played important roles on the superior HSA sensing ability. The findings indicate that minor changes in design strategy can be advantageous while developing long-wavelength (far red or near infrared) emitting fluorophores for biosensing and bioimaging.

具有优异光物理特性的对环境敏感的小分子荧光团的合理设计对于基于荧光分析的生物传感至关重要。本文中，我们开发了一种新的供体-受体荧光团，用于定量检测水性样品中的人血清白蛋白（HSA）。荧光团很容易通过Knoevenagel缩合制备，并显示出优异的光物理性质和正溶剂溶变色。荧光团的设计基于氮供体-共轭-腈受体（D-π-A），以保持有效的分子内电荷转移和长波发射。在HSA存在下，荧光团显示出显着的“开启”荧光，从而可以定量测定水性缓冲液样品中的蛋白质。荧光团的结构和电子性质在优异的HSA感测能力上起着重要作用。研究结果表明，在开发长波长（远红外或近红外）发射荧光团用于生物传感和生物成像的过程中，设计策略的微小变化可能是有利的。