[NMR paper] Cryptophane nanoscale assemblies expand 129Xe NMR biosensing.

[nmrlearner]

Cryptophane nanoscale assemblies expand 129Xe NMR biosensing.

Related Articles Cryptophane nanoscale assemblies expand 129Xe NMR biosensing.

Anal Chem. 2018 May 21;:

Authors: Zemerov SD, Roose BW, Greenberg ML, Wang Y, Dmochowski IJ

Abstract
Cryptophane-based biosensors are promising agents for the ultrasensitive detection of biomedically relevant targets via 129Xe NMR. Dynamic light scattering revealed that cryptophanes form water-soluble aggregates of tens-to-hundreds of nanometers in size. Acridine orange fluorescence quenching assays allowed quantitation of aggregation state, with critical concentration rang-ing from 200 to 600 nM, depending on the cryptophane species in solution. Addition of excess carbonic anhydrase (CA) pro-tein target to a benzenesulfonamide-functionalized cryptophane biosensor (C8B) led to C8B disaggregation and produced the expected 1:1 C8B-CA complex. C8B showed higher affinity at 298 K for the cytoplasmic isozyme CAII than the extracellular CAXII isozyme, a biomarker of cancer. Using hyper-CEST NMR, we explored the role of stoichiometry in detecting these two isozymes. At CA-saturating conditions, we observed that isozyme CAII produces a larger 129Xe NMR chemical shift change (?= 5.9 ppm, relative to free biosensor) than CAXII (?= 2.7 ppm), which indicates the strong potential for isozyme-specific detec-tion. However, stoichiometry-dependent chemical shift data indicated that biosensor disaggregation contributes to the observed 129Xe NMR chemical shift change that is normally assigned to biosensor-target binding. Finally, we determined that monomeric cryptophane solutions improve hyper-CEST saturation contrast, which enables ultrasensitive detection of biosensor-protein complexes. These insights into cryptophane-solution behavior support further development of xenon biosensors, but will re-quire reinterpretation of the data previously obtained for many water-soluble cryptophanes.


PMID: 29782149 [PubMed - as supplied by publisher]



More...