Recent advances of ambient mass spectrometry imaging for biological tissues: A review

Ambient mass spectrometry imaging (AMSI) is a molecular imaging technique developed in recent years for in situ and real time visualization of the distribution of chemical compounds in biological tissues without the need of labeling or staining. With the development for more than one decade, AMSI becomes a powerful molecular imaging technique in variousfields such as forensics, metabolomics, cancer diagnosis, and drug monitoring. In this review, we describe the recent advances of AMSI for imaging biological tissues in details. Three types of AMSI techniques based on different ionization mechanisms and analytical strategies are summarized, i.e., direct desorption/ionization of analytes for AMSI, desorption and then ionization of analytes for AMSI, and extraction of analytes for AMSI, and the features of them are presented from the aspects of tissue origin, target image molecule, and spatial resolution among others. In addition, future development directions for AMSI are discussed.