A Novel Spectral Barcoding and Classification Approach for Complex Biological Samples Using Multiexcitation Raman...

Area of Science:

• Biophotonics and Spectroscopy
• Neuroscience and Neurodegenerative Diseases
• Biomolecular Analysis

Background:

• Neurodegenerative diseases (NDDs) present diagnostic challenges due to overlapping clinical symptoms.
• Accurate classification of NDDs is crucial for effective patient management and treatment.
• Label-free detection methods are sought after to simplify biological sample analysis.

Purpose of the Study:

• To develop and apply a novel multiexcitation (MX) Raman spectroscopy methodology for enhanced label-free classification of complex biological samples.
• To investigate the contribution of different spectral information sources (excitation wavelengths, polarization, autofluorescence) for NDD classification.
• To engineer spectral barcodes for improved sample discrimination.

Main Methods:

• Utilized post-mortem brain tissue from patients with various neurodegenerative diseases (NDDs).
• Employed multiexcitation (MX) Raman spectroscopy with varying laser wavelengths (532 nm-785 nm) and polarization states.
• Analyzed spectral data using linear discriminant analysis (LDA) and engineered spectral barcodes by filtering features.

Main Results:

• MX-Raman spectra achieved an average classification accuracy of 96.7% for 5 NDD classes, significantly outperforming conventional single-excitation Raman spectroscopy (78.5%-85.6%).
• Combining spectral information from distinct laser wavelengths proved most effective for classification.
• Engineered spectral barcodes, comprising minimal disease-specific features, enhanced unsupervised and cross-validated clustering.

Conclusions:

• The developed optical MX-Raman methodology significantly enhances the identification and distinction of complex biological samples by increasing spectral information content.
• The effectiveness relies on using independent and class-descriptive spectral information.
• Future translation to biofluids could aid in the diagnosis and stratification of dementia and other diseases like cancer and infectious disease.