Microenvironment-sensitive Fluorescent Dyes Synthesis And Research For Albumin Recognition

Fluorescent analytical technology was one of most widely used biological technologys due to its high sensitivity, selectivity, and simple procedure for in situ target sensing. In protein labeling technologies, fluorescence labeling shows advantages over other methods which attracts lots of attention.Albumin content in biological fluids especially in urine is related to renal disease and diabetes, which makes it a key indicator for the early diagnosis of renal disease and intensified treatment of diabetes mellitus. We have synthesized four small molecule dyes SA1-SA4 which had good fluorescence response to HSA based on TICT and molecular motor strategy. These dyes exhibited colorful fluorescent emission from visible region to near infrared (541-685 nm) through structure modification. After binding with the hydrophobic cavity of HSA, their fluorescence intensity increased dramatically with obvious blue-shifts due to the changes of the microenvironment and suppression of the free rotation of molecules. The detection had no interference from common proteins, amino acids, cations and anions in biological system, while obvious fluorescence change could be observed immediately after addition of HSA and becomed saturated within 10 sec. Besides, the detection limits (3a/slope) were as low as 0.1 mg/L and 0.076 mg/L for SA1 and SA4 respectively. More importantly, SA4 can be utilized for the detection of HSA in real urine samples and the fluorescence intensity had a good liner relationship with HSA content.We synthesized two dyes ES1 and ES2 based on TICT and they showed fluorescence turn on after binding with HSA. Drug diplace experiments proved these two dyes binded to the FA1 site of HSA. Then, we used one dye Rl which bind to the site I and ES1 or ES2 to form FRET system. This FRET system had high resonance energy transfer efficiency and the distance between donor and acceptor was 2-3 nm. The FRET system could be utilized for the ratiometric detection of Ag+ and the detection limit was as low as 0.02 mg/L. This ratiometric fluorescent probe utlized the fluorescence intensity of two emission wavelengths as detection signal, thus they had higher sensitivity and selectivity and wider dynamic response range.