Chance J J, Purdy W C
Department of Chemistry, McGill University, Montreal, Quebec, Canada.
Anal Chem. 1996 Sep 15;68(18):3104-11. doi: 10.1021/ac960282e.
A novel chemical sensor for bile acids is described. A 10-MHz piezoelectric crystal operating in the thickness-shear mode (TSM) is coated on one side with cholestyramine resin and mounted in a batch-mode sensor block which exposes the coating to solution. After sample injection, the binding process is observed in real time as a drop in frequency as the bile salt binds to the coating, reaching > 90% completion within 10 min with most of the binding occurring within the first minute. Linear calibration curves are generated with sensitivity increasing in the order cholate approximately glycocholate < taurocholate < < taurodeoxycholate. Detection limits in water are in the range 0.2-9 nmol and are better than those observed in phosphate buffer. A multistep regeneration protocol allows the coating to be reused more than 400 times over a period of several months. Precision for replicate injections is approximately 10% RSD and depends on the reproducibility of the regeneration and injection steps. In terms of the binding process, hydrophobic interactions are observed to be of importance in the ability of bile salts to displace other counterions. However, anions with greater charge density also appear to compete effectively for binding sites on the resin. In particular, at equimolar concentrations of citrate and bile salt, the trivalent citrate anion reduces the amount of bile salt binding by approximately 40%. This suggests that the efficiency of cholestyramine-based bile salt sequestering drugs used in the reduction of hypercholesterolemia may be improved by eliminating citric acid as an excipient and avoiding the use of fruit juices during ingestion.
描述了一种新型的胆汁酸化学传感器。一个工作在厚度剪切模式（TSM）的10MHz压电晶体一侧涂有消胆胺树脂，并安装在一个批处理模式的传感器模块中，该模块使涂层暴露于溶液中。进样后，随着胆盐与涂层结合，频率下降，实时观察到结合过程，在10分钟内结合完成率>90%，大部分结合发生在第一分钟内。生成线性校准曲线，灵敏度按胆酸盐<甘氨胆酸盐<牛磺胆酸盐<<牛磺去氧胆酸盐的顺序增加。在水中的检测限为0.2 - 9 nmol，优于在磷酸盐缓冲液中观察到的检测限。一个多步骤再生方案允许涂层在几个月的时间内重复使用400多次。重复进样的精密度约为10%相对标准偏差（RSD），并取决于再生和进样步骤的重现性。就结合过程而言，观察到疏水相互作用在胆盐取代其他抗衡离子的能力中很重要。然而，电荷密度更高的阴离子似乎也能有效地竞争树脂上的结合位点。特别是，在柠檬酸盐和胆盐等摩尔浓度下，三价柠檬酸盐阴离子使胆盐结合量减少约40%。这表明，通过去除柠檬酸作为辅料并避免在摄入期间饮用果汁，用于降低高胆固醇血症的基于消胆胺的胆盐螯合药物的效率可能会提高。
