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通过微波辅助氧化法降解壳聚糖制得低聚窄分子量分布壳聚糖(低窄壳糖),LNCS6(聚合度为6,Mw/Mn=1.08),并以LNCS6为载体,键接7-羟基-8-醛基香豆素(CA)为荧光基团、二乙烯三胺五乙酸(DTPA)为络合基团,络合三价钆离子最终制得一种潜在的核磁共振(MR)/荧光双功能成像分子探针Gd[DTPA/CA-LNCS6]。研究了其磁共振成像效果以及荧光特性,并通过等温微量热滴定法(ITC)测定了产物与牛血清蛋白(BSA)之间的结合常数及热力学参数。结果表明,所得产物具有较高的体外磁共振成像效果〔r1=13.71 L/(mmol·s)〕,远高于目前临床使用的马根维显〔r1=3.63 L/(mmol·s)〕。同时,其具有显著的荧光特性(λmax=438 nm),与牛血清蛋白之间结合常数Ka>104,适用于血液输送,对这类探针精细化工中间体的合成具有较好的参考与借鉴作用。
The chitosan with low molecular weight distribution (LPSS), LNCS6 (degree of polymerization 6, Mw / Mn = 1.08) was prepared by microwave-assisted oxidative degradation of chitosan. LNCS6 was used as a carrier to bond 7- Hydroxy-8-aldehyde-based coumarin (CA) is a fluorophore, and diethylenetriaminepentaacetic acid (DTPA) is a complexing group that complexes with trivalent gadolinium ions to produce a potential nuclear magnetic resonance (MR) / Fluorescent Bifunctional Imaging Molecular Probes Gd [DTPA / CA-LNCS6]. The magnetic resonance imaging and fluorescence properties of the product were studied. The binding constants and thermodynamic parameters of the product with bovine serum albumin (BSA) were determined by isothermal microcalorimetry (ITC). The results showed that the obtained product had a higher magnetic resonance imaging effect in vitro [r1 = 13.71 L / (mmol · s)], much higher than that of the current clinical use of rhGM [r1 = 3.63 L / (mmol · s)]. At the same time, it has a remarkable fluorescence property (λmax = 438 nm). The binding constant with bovine serum albumin (Ka> 104) is suitable for blood transfusion. It has a good reference for the synthesis of these chemical intermediates effect.