Issue 14, 2016

Using membrane composition to fine-tune the pKa of an optical liposome pH sensor

Abstract

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 pKa 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 pKa 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 pKa values by <1 unit. The results show that rational modification of the membrane composition is a general non-covalent way to fine-tune the pKa of an optical liposome sensor for optimal pH sensing performance.

Graphical abstract: Using membrane composition to fine-tune the pKa of an optical liposome pH sensor

Supplementary files

Article information

Article type
Paper
Submitted
23 10 2015
Accepted
01 12 2015
First published
01 12 2015

J. Mater. Chem. C, 2016,4, 2925-2930

Using membrane composition to fine-tune the pKa of an optical liposome pH sensor

K. J. Clear, K. Virga, L. Gray and B. D. Smith, J. Mater. Chem. C, 2016, 4, 2925 DOI: 10.1039/C5TC03480A

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