Nanoscale spectroscopy and imaging of hemoglobin

Abstract

Sub diffraction limited infrared absorption imaging of hemoglobin was performed by coupling IR optics with an atomic force microscope. Comparisons between the AFM topography and IR absorption images of micron sized hemoglobin features are presented, along with nanoscale IR spectroscopic analysis of the metalloprotein.

Quantifying nanoscale biochemical heterogeneity in human epithelial cancer cells using combined AFM and PTIR absorption nanoimaging

“…These studies indicate that while complex biological systems can be chemically probed with this method, the actual deflection observed is not only a function of the material absorption coefficient, but also of the amount of the absorbing material that is present in the vicinity of the tip [21]. This is likely a significant contributor to the intensity variation observed in previous studies when imaging the same region at different wavelengths [18][19][20][21]. Further to this we illustrate that a combined topographic-IR analysis not only permits chemical discrimination on the nanoscale, but can also give insight into chemical heterogeneity at sub-optical diffraction limited resolution.…”

“…This has led to the use of the PTIR technique for absorption imaging and spectroscopy of numerous biomaterials, including lipids [17], proteins [18], bacteria [19] and live cells [20]. When probing small features such as viruses within a host organism [21], the power of the method for discriminating heterogeneous chemical signals far below the optical diffraction limit becomes apparent. )…”

“…However, where these properties are approximately invariant as a function of wavelength and position, spectra and infrared maps of the local absorption co-efficient can be obtained. This has led to the use of the PTIR technique for absorption imaging and spectroscopy of numerous biomaterials, including lipids [17], proteins [18], bacteria [19] and live cells [20]. When probing small features such as a single phage within a host organism [21], the power of the method for discriminating heterogeneous chemical signals far below the optical diffraction limit becomes apparent.…”

Human epithelial cancer cells studied using combined AFM-IR absorption nanoimaging

“…Such studies has stimulated the growth of nano-optical imaging tools [9][10][11][12][13]. Such nano-tools have potential to advance the understanding of living systems by revealing nanoscale features and structures, previously unresolvable with diffraction limited optical methods.…”

“…Such nano-tools have potential to advance the understanding of living systems by revealing nanoscale features and structures, previously unresolvable with diffraction limited optical methods. One such emergent method is nanoscale infrared (IR) nanospectroscopic absorption imaging, which can perform spectroscopic mapping and label free chemical identification of cell components on the nanoscale [9][10][11][12][13]. The technique uses a small, sensitive cantilever (such as an AFM cantilever) in contact with the sample surface during pulsed photothermal excitation.…”