What is it about?
Large density of gap plasmon hot spots from clusters of nanoparticles produces a high surface-enhanced Raman scattering (SERS) enhancement. A homogeneous and isotropic arrangement of these clusters is driven by block copolymer micelles that self-organize into a near hyperuniform disordered pattern. This helps suppressing the fluctuations of the spot-to-spot SERS response even for confocal detection. The spatially flat SERS response allows reconstructing the label-free chemical map of a challenging cell, the red blood cell. The hemoglobin Raman signature is used as a contrast medium to validate membrane glycoprotein detection on the living cell. Numerical simulations support the experimental data.
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Why is it important?
Label-free chemical imaging of live cell membranes represents a hot topic of bio-medical research, potentially providing access to the molecular basis of many significant membrane-related diseases. Herein, we present surface-enhanced Raman scattering (SERS) substrates based on a homogeneous and isotropic random close-packing of silver nanoclusters and characterized by near-hyperuniform disorder. These SERS substrates reveal excellent reproducibility with spatially flat SERS enhancement factor and single molecule sensitivity on centimeter scale. This allows a robust SERS imaging of cell membranes - here demonstrated on erythrocytes - which opens new routes for quantitative surface analysis and dynamic probing of living cells.
Perspectives
Label-free chemical imaging with time-resolution potential could unveil fundamental mechanisms about the cell membrane. Differential analysis between control and diseased cells might allow monitoring the dynamics of the cell surface molecular regulation under external mechanical stimuli or drug exposure with the benefit of visualizing possible effects. In this direction, loading gold or bimetallic NPs into BCP micelles with the same protocol used for silver is expected to produce highly performing SERS substrates with larger biocompatibility and plasmon resonance tunability.
Dr Gianluigi Zito
Universita degli Studi di Napoli Federico II
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This page is a summary of: Surface-enhanced Raman imaging of cell membrane by a highly homogeneous and isotropic silver nanostructure, Nanoscale, January 2015, Royal Society of Chemistry,
DOI: 10.1039/c5nr01341k.
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