Mass Spectrometric Lipid Profiles of Picosecond Infrared Laser‐Generated Tissue Aerosols Discriminate Different Brain Tissues

Abstract

Background and Objectives A picosecond infrared laser (PIRL) has recently been demonstrated to cut biological tissue without scar formation based on the minimal destructive action on the surrounding cells. During cutting with PIRL, the irradiated tissue is ablated by a cold vaporization process termed desorption by impulsive vibrational excitation. In the resulting aerosol, all molecules are dissolved in small droplets and even labile biomolecules like proteins remain intact after ablation. It is hypothesized that these properties enable the PIRL in combination with mass spectrometry as an intelligent laser scalpel for guided surgery. In this study, it was tested if PIRL‐generated tissue aerosols are applicable for direct analysis with mass spectrometry, and if the acquired mass spectra can be used to discriminate different brain areas. Materials and Methods Brain tissues were irradiated with PIRL. The aerosols were collected and directly infused into a mass spectrometer via electrospray ionization without any sample preparation or lipid extraction. Results The laser produced clear cuts with no marks of burning. Lipids from five different classes were identified in the mass spectra of all samples. By principal component analysis the different brain areas were clearly distinguishable from each other. Conclusions The results demonstrate the potential for real‐time analysis of lipids with a PIRL‐based laser scalpel, coupled to a mass spectrometer, for the discrimination of tissues during surgeries. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Tissue Sampling and Homogenization in the Sub-Microliter Scale with a Nanosecond Infrared Laser (NIRL) for Mass Spectrometric Proteomics

“…Compared to mechanical homogenization, this is a very gentle method of sample extraction and homogenization, avoiding time-consuming preparation steps. Over the past decade, this tissue sampling and homogenization has been successfully demonstrated with a PIRL, nanosecond infrared laser (NIRL) and even a high-energy microsecond infrared laser (MIRL) with subsequent mass spectrometric proteomics [ 4 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ] or directly coupled to real-time MS instruments, such as the “SpiderMass” technology [ 22 , 23 , 24 , 25 , 26 ].…”

“…In our previous studies we utilized a picosecond infrared laser (PIRL) [ 4 , 13 , 16 , 19 ] as well as a microsecond infrared laser (MIRL) [ 15 , 16 ] for tissue sampling and homogenization for subsequent proteomics and lipidomics. In a first study by Kwiatkowski et al (2015), it was shown that tissue sampling with the PIRL makes proteins accessible in a wide range from a few kilodaltons to several million daltons.…”

Lipidome Analysis of Oropharyngeal Tumor Tissues Using Nanosecond Infrared Laser (NIRL) Tissue Sampling and Subsequent Mass Spectrometry

“…To our knowledge, this is the smallest reported sample volume for shotgun lipidomics with IRL-based tissue sampling, thus demonstrating the enormous potential of spatial lipidomics. The approach is much faster than classical mechanical homogenization and more volume efficient than the IRL-based sampling described in our previous study, which had an ablation volume of 1 mL (a factor of 2000) and utilized an aerosol cryotrap [40].…”

“…Besides the resulting high cutting precision and significant superiority concerning wound healing and scar formation compared with other lasers, the application of DIVE generates an aerosol that is particularly suitable for subsequent differential quantitative proteomics and lipidomics. Several studies have tested the function of real-time MS concepts for tissue differentiation [32,40,41]. Utilizing laser-based aerosolization [12,42,43] or tissue surface extraction [33] combined with real-time MS enables the characterization of different tissue pathologies (cancer, infection, or inflammation) within seconds based on lipid profile signatures.…”

In situ Detecting Lipids as Potential Biomarkers for the Diagnosis and Prognosis of Intrahepatic Cholangiocarcinoma

“…Previous research have demonstrated the use of mass spectrum coupled with a PIRL-based laser scalpel in discriminating different brain areas. 34 Cancer screening of body fluids was the other possible way using mass spectrum which may improve the survival time prognosis of patients. The pathologic confirmation of the diagnosis is necessary before any non-surgical treatment and can be challenging in ICC.…”