SHG Imaging of Trace Crystallinity in Amorphous Matrices
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Solution Overview
Problem
Current methods are inadequate for accurately quantifying trace crystallinity in amorphous solids, particularly in pharmaceutical compounds, as they fail to provide microscopic information and are not suitable for routine analysis, leading to incomplete understanding of solid-state phase transformations and potential biases in crystallization kinetics.
Innovation Solution
An apparatus and method using second harmonic generation (SHG) signals to characterize crystalline structures in amorphous matrices, employing a coherent optical source, raster scan generator, and sample holder to detect SHG signals at various depths, enabling visualization of time-dependent physical processes and temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If X-ray diffraction or thermal analysis techniques are used to study mechanically-induced crystallinity loss, then the reduction in Bragg peak intensity can be observed, but the techniques cannot distinguish between thermodynamic disordering and kinetic disordering, leading to ambiguous interpretation of diffuse halos
Solution Approach 1:
The patent replaces traditional mechanical/X-ray diffraction techniques with second harmonic generation (SHG) optical imaging. SHG provides microscopic visualization of crystalline domains with spatial resolution, enabling distinction between thermodynamic and kinetic disordering mechanisms that were previously ambiguous in bulk measurements.
Solution Approach 2:
The patent transitions from bulk-averaged measurements (X-ray diffraction) to spatially-resolved microscopic imaging (SHG). This dimensional change from macroscopic to microscopic scale reveals heterogeneous crystalline domains and their evolution, providing information about disordering mechanisms that was previously lost in bulk measurements.
2Measurement precision
If conventional microscopy or spectroscopy is used for routine crystallinity analysis, then the analysis can be performed relatively quickly, but the detection sensitivity for trace crystallinity below 0.1% is insufficient
Solution Approach 1:
The patent exploits the nonlinear optical parameter of second harmonic generation, which provides exceptional contrast for crystalline materials. The SHG signal intensity is proportional to the square of the incident light intensity and selectively generated by non-centrosymmetric crystalline structures, enabling detection of trace crystallinity at the 0.04% level with high signal-to-noise ratio.
3Productivity
If mechanical grinding is used to reduce particle size and enhance dissolution rate, then the crystallinity loss can be achieved, but the process induces solid-state phase transformations and creates heterogeneous mixtures of crystalline and amorphous phases that affect drug stability
Solution Approach 1:
The patent applies preliminary cryogenic treatment before mechanical grinding to minimize local heating and reduce solid-state phase transformations. By pre-cooling the material to cryogenic temperatures, the mechanical energy is dissipated without inducing excessive heating that would cause unwanted phase changes and crystallinity loss.
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
Enables rapid and sensitive detection of trace crystallinity down to 0.04% with high signal-to-noise ratio, providing macroscopic and microscopic insights into crystallization behavior, and offering advantages over traditional methods like PXRD and Raman spectroscopy in terms of acquisition time and data coverage.
Implementation Method 1
An apparatus for measuring second harmonic generated (SHG) signals
Data Source
AI summary
An apparatus and method for performing volume scanning of a sample comprised of chiral materials disposed in a matrix of non-chiral materials is disclosed. A laser is raster scanned in a plane of the volume such that the intensity of energy in the focal region is sufficient to generate second harmonic (SHG) energy. This energy is detected and may be processed into three dimensional images of the volume. The raster pattern is repeatedly stepped over an area of the sample so as to produce three dimensional images of time-dependent processes.