Evaluating pathological levels of intracellular cholesterol through Raman and surface-enhanced Raman spectroscopies

Area of Science:

• Biophysics
• Cell Biology
• Medical Diagnostics

Background:

• Accurate intracellular cholesterol quantification is vital for understanding cellular functions and diagnosing metabolic disorders.
• Cholesterol metabolism disorders, such as Niemann-Pick disease (NPC), are characterized by abnormal cholesterol accumulation.

Purpose of the Study:

• To evaluate Raman spectroscopy (RS) and surface-enhanced Raman spectroscopy (SERS) for quantifying intracellular cholesterol.
• To assess the potential of RS and SERS in diagnosing cholesterol-related diseases, specifically Niemann-Pick disease (NPC).

Main Methods:

• Human fibroblasts were incubated with varying concentrations of cholesterol-methyl-β-cyclodextrin.
• Intracellular cholesterol levels were measured using Raman spectroscopy (RS) and surface-enhanced Raman spectroscopy (SERS).
• Gold nanoparticles were used as signal enhancers in SERS, and their cellular localization was investigated.

Main Results:

• Both RS and SERS accurately detected high intracellular cholesterol levels in fibroblasts from Niemann-Pick disease (NPC) patients.
• SERS demonstrated superior accuracy compared to RS and filipin III staining in distinguishing between NPC patient fibroblasts.
• Gold nanoparticles used in SERS were found to be internalized and localized in lysosomes, enhancing signal sensitivity.

Conclusions:

• RS and SERS are sensitive and accurate methods for evaluating intracellular cholesterol content.
• These spectroscopic techniques offer potential for developing optical tools for ex-vivo screening and monitoring of cholesterol metabolism disorders.
• SERS, particularly with internalized gold nanoparticles, shows significant promise for precise diagnosis of NPC.