Chromophore-Charged Derivatisation Agent for LDI-MS Detection
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Solution Overview
Problem
Existing mass spectrometry methods face challenges in achieving high sensitivity for analyzing analytes from complex biological matrices, particularly for low-abundance analytes or those present in limited sample quantities, due to insufficient labeling efficiencies, generation of structural isomers, and interference from matrix-based measurements, which are not optimized for laser desorption ionization (LDI) applications.
Innovation Solution
A derivatization agent with a chromophore absorbing in the range of 280 to 400 nm, a permanently charged unit, and a reactive group, which enhances energy transfer and adds sufficient molecular weight, enabling high-sensitive LDI-MS measurements by ensuring efficient fragmentation and reducing background interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing derivatization reagents are used to improve sensitivity for low-abundance analytes, then detection sensitivity may be enhanced, but background interference from matrix-based measurements increases and labeling efficiency remains insufficient
Solution Approach 1:
The derivatization agent is segmented into three functional units: a chromophore unit (C) for laser energy absorption, a charged unit (Z) for providing permanent charge and improving ionization, and a reactive group (X) for specific analyte labeling. This segmentation allows each unit to perform its function optimally without interfering with others, reducing background noise while enhancing sensitivity
Solution Approach 2:
The patent changes the key parameter of the derivatization agent by incorporating a chromophore with specific absorption characteristics (maximum absorption between 280-400 nm) that matches the laser wavelength used in LDI-MS. This parameter optimization enables efficient energy transfer from the laser to the derivatized analyte, significantly improving detection sensitivity while the charged unit simultaneously reduces background interference through selective ionization
2Reliability
If derivatization reagents with charged units and neutral loss units are used, then ionization efficiency improves, but structural isomers are generated and labeling efficiency remains insufficient
Solution Approach 1:
The reactive group (X) is designed with local quality specific to the target analyte functional groups, enabling site-specific labeling. This ensures that derivatization occurs at predetermined locations on the analyte molecule, preventing structural isomer formation while maintaining high ionization efficiency through the charged unit (Z)
Solution Approach 2:
The derivatization agent combines three distinct functional units (chromophore C, charged unit Z, and reactive group X) into a single composite molecule. This composite structure integrates the benefits of efficient laser energy absorption, permanent charge for improved ionization, and specific reactive labeling, achieving both high ionization efficiency and labeling specificity simultaneously
3Measurement precision
If known derivatization reagents are used to enhance detection sensitivity, then sensitivity for low-abundance analytes improves, but the workflow of sample preparation and MS measurement is negatively affected
Solution Approach 1:
The invention extracts and eliminates the problematic large structural components from known derivatization reagents, retaining only the essential functional units (chromophore, charged unit, and reactive group) in a compact configuration. This reduction in molecular size prevents interference with chromatographic separation and simplifies the overall workflow while maintaining enhanced detection sensitivity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The derivatization agent improves sensitivity and specificity in LDI-MS by providing a large mass shift and selective neutral loss fragmentation, allowing for sensitive detection of analytes with reduced background noise, especially in the lower molecular weight region.
Implementation Method 1
laser desorption ionization (LDI), in particular matrix-free laser desorption ionization (SALDI)
Implementation Method 2
Z is a charged unit comprising at least one permanently charged moiety
Data Source
AI summary
In a first aspect, the invention relates to a derivatisation agent, preferably derivatisation agent for analytes intended to be analysed via LDI-MS, comprising a structural element of formula (I) C-L1-Z-(L2)p-X, wherein C is a chromophore having an absorption maximum in the range of from 280 to 400 nm; Z is a charged unit comprising at least one permanently charged moiety; X is a reactive group; L1, L2 are each a linker unit; and p is either zero or 1.A second aspect of the invention is related to a kit comprising the derivatisation agent according to the first aspect. In a third aspect, the invention is directed to a use of the derivatisation agent according to the first aspect for the mass spectrometric determination of an analyte molecule, wherein the mass spectrometric determination is LDI-MS. A fourth aspect of the invention relates to a conjugate of a derivatisation agent according to the first aspect and an analyte, wherein the conjugate has the structure of formula (II) C-L1-Z-(L2)p-Xa-Ya-A, wherein C, L1, L2, p, Z and N are as defined in the context of the first aspect; Xa is a remainder of a reactive group X as defined in the context of the first aspect; A is the analyte and Ya is the remainder of a reactive group Y bound to the analyte A, which has reacted with the reactive group X of the derivatisation agent thus forming a covalent bound between Xa and Ya. A fifth aspect of the invention is related to a method for the mass spectrometric determination of an analyte molecule comprising the steps: (a) providing an analyte of interest; (b) providing a derivatisation agent comprising a structure of formula (I) as defined in the context of the first aspect; (c) reacting the analyte provided according to (a) with the derivatisation agent provided according to (b), whereby a conjugate of the analyte and the derivatisation agent is formed, and (d) subjecting the conjugate formed in (c) to a mass spectrometric analysis, wherein the mass spectrometric analysis is preferably LDI-MS.