Using membrane composition to fine-tune the pK(a) of an optical liposome pH sensor

作者：Clear Kasey J; Virga Katelyn; Gray Lawrence; Smith Bradley D

来源：Journal of Materials Chemistry C, 2016, 4(14): 2925-2930.

DOI：10.1039/c5tc03480a

Liposomes containing membrane-anchored pH-sensitive optical probes are valuable sensors for monitoring pH in various biomedical samples. The sensitivity of the sensor is maximized when the probe pK(a) is close to the expected sample pH. While some biomedical samples are close to neutral pH there are several circumstances where the pH is 1 or 2 units lower. Thus, there is a need to fine-tune the probe pK(a) in a predictable way. This investigation examined two lipid-conjugated optical probes, each with appended deep-red cyanine dyes containing indoline nitrogen atoms that are protonated in acid. The presence of anionic phospholipids in the liposomes stabilized the protonated probes and increased the probe pK(a) values by <1 unit. The results show that rational modification of the membrane composition is a general non-covalent way to fine-tune the pK(a) of an optical liposome sensor for optimal pH sensing performance.

• 出版日期2016