Capillary array electrophoresis imaging of biochemicals in tissue sections

It is of great significance to reveal the molecular distribution images in biological tissues, which has led to the bloom of mass spectrometry imaging. Unfortunately, its application is encountering the resistance of high technical barriers and equipment cost, as well as the inability to image substances that cannot be desorbed or ionized, or cannot be separated by their mass-to-charge ratios. Herein presented is a complementary and costeffective method called capillary array electrophoresis (CAE) imaging. To have the information of molecules and their spatial location, a gridding cutter was fabricated to orderly dissect a tissue section into a leakproof array of micro wells enclosed by the grid-blade arrays. After in situ extraction and fluorophore-labeling of analytes, the samples in the wells were directly subjected to CAE-LIF (laser-induced fluorescence), and the molecular distribution images were depicted with the separated peaks. The practicability was demonstrated by CAE imaging of rat brain tissue sections with amino acid neurotransmitters (e.g., glutamine, 4-aminobutyric acid, alanine, glutamic acid and aspartic acid) as targets. The resultant images showed the global differences of molecular distributions, with a spatial resolution of 1000 mu m that was presently determined by the well width but ultimately by the bore size of capillary (down to 10-50 mu m). CAE imaging can hence be promising for its low cost, low technical barriers and abundant mechanisms to separate the charged and non-charged, chiral and nonchiral substances.

Automated summary

Capillary array electrophoresis (CAE) imaging is a cost-effective method that can reveal molecular distribution images in biological tissues with a spatial resolution that can be improved by capillary bore size. The method has the capability to separate charged and non-charged, chiral and nonchiral substances, showing promise for various applications.