Amorphous Conjugated Polymers as Efficient Dual-Mode MALDI Matrices for Low-Molecular-Weight Analytes

Area of Science:

• Analytical Chemistry
• Materials Science

Background:

• Matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) typically uses small-molecule matrices for analyte co-crystallization.
• Recent work demonstrated semi-crystalline polymers as efficient, dual-mode matrices for low-molecular-weight compounds (LMWCs) in MALDI MS and MALDI MS Imaging.

Purpose of the Study:

• To investigate and compare the matrix performance of two specific amorphous fluorene/naphthalene diimide co-polymers: P(TNDIT-Fl(C4 C2)) and P(TNDIT-Fl(C10 C8)).
• To evaluate their suitability as dual-mode matrices for LMWC detection in MALDI MS.

Main Methods:

• X-ray diffraction (XRD) measurements to confirm amorphous nature.
• Spectroscopic analysis to determine absorption values at 355 nm (Nd:YAG laser wavelength).
• Evaluation of matrix performance in MALDI MS for LMWC detection, assessing signal intensity and mode (positive/negative).

Main Results:

• Both P(TNDIT-Fl(C4 C2)) and P(TNDIT-Fl(C10 C8)) co-polymers are fully amorphous.
• They exhibit high absorption at 355 nm (73% and 67%, respectively) and are solution processable.
• As matrices, they enable dual-mode detection of LMWCs with minimal matrix-related ions (MALDI-silent).
• Signal intensities achieved with these amorphous matrices are comparable or superior to those obtained with semi-crystalline polymer matrices.

Conclusions:

• Amorphous fluorene/naphthalene diimide co-polymers are effective and versatile matrices for MALDI MS and MALDI MS Imaging.
• These matrices facilitate efficient analyte inclusion within their amorphous regions, leading to high signal intensities.
• The findings suggest that amorphous polymer matrices can be a viable alternative to traditional small-molecule matrices and semi-crystalline polymers.