Multispectral Atomic Force Microscopy-Infrared Nano-Imaging of Malaria Infected Red Blood Cells

Noninvasive Subcellular Imaging Using Atomic Force Acoustic Microscopy (AFAM)

We report an imaging approach applying the atomic force acoustic microscopy (AFAM), which has unique potential for nondestructive imaging of cell internal structures. To obtain high spatial resolution images, we optimized the significant imaging parameters, including scanning speeds, feedback configurations and acoustic frequencies of an AFAM system, to increase the amplitude of the acoustic signal and to stabilize the morphological signals. We also combined the acoustic amplitude and phase signals, and generated pseudo-color figures for better illustration of subcellular features such as pseudopodia, membranes and nucleus-like. The subcellular structural image atlas can describe nanoscale details of multiple samples and provide clearer images of the subcellular features compared to other conventional techniques. This study builds a strong basis of transmission AFAM for cell imaging, which can help researchers to clarify the cell structures in diverse biological fields and push the understanding of biology evolution to a new stage.

Biochemical detection of fatal hypothermia and hyperthermia in affected rat hypothalamus tissues by Fourier transform infrared spectroscopy

It is difficult to determinate the cause of death from exposure to fatal hypothermia and hyperthermia in forensic casework. Here, we present a state-of-the-art study that employs Fourier-transform infrared (FTIR) spectroscopy to investigate the hypothalamus tissues of fatal hypothermic, fatal hyperthermic and normothermic rats to determine forensically significant biomarkers related to fatal hypothermia and hyperthermia. Our results revealed that the spectral variations in the lipid, protein, carbohydrate and nucleic acid components are highly different for hypothalamuses after exposure to fatal hypothermic, fatal hyperthermic and normothermic conditions. In comparison with the normothermia group, the fatal hypothermia and hyperthermia groups contained higher total lipid amounts but were lower in unsaturated lipids. Additionally, their cell membranes were found to have less motional freedom. Among these three groups, the fatal hyperthermia group contained the lowest total proteins and carbohydrates and the highest aggregated and dysfunctional proteins, while the fatal hypothermia group contained the highest level of nucleic acids. In conclusion, this study demonstrates that FTIR spectroscopy has the potential to become a reliable method for the biochemical characterization of fatal hypothermia and hyperthermia hypothalamus tissues, and this could be used as a postmortem diagnostic feature in fatal hypothermia and hyperthermia deaths.

Nanoscale Structural Organization of Plant Epicuticular Wax Probed by Atomic Force Microscope Infrared Spectroscopy

The cuticle covers external surfaces of plants, protecting them from biotic and abiotic stress factors. Epicuticular wax on the outer surface of the cuticle modifies reflectance and water loss from plant surfaces and has direct and indirect effects on photosynthesis. Variation in epicuticular wax accumulation, composition, and nanoscale structural organization impacts its biological function. Atomic force microscope infrared spectroscopy (AFM-IR) was utilized to investigate the internal and external surfaces of the cuticle of Sorghum bicolor, an important drought-tolerant cereal, forage, and high-biomass crop. AFM-IR revealed striking heterogeneity in chemical composition within and between the surfaces of the cuticle. The wax aggregate crystallinity and distribution of chemical functional groups across the surfaces was also probed and compared. These results, along with the noninvasive nondestructive nature of the method, suggest that AFM-IR can be used to investigate mechanisms of wax deposition and transport of charged molecules through the plant cuticle.

Synchrotron macro ATR-FTIR microspectroscopy for high-resolution chemical mapping of single cells

Coupling synchrotron IR beam to an ATR element enhances spatial resolution suited for high-resolution single cell analysis in biology, medicine and environmental science.

Organometallic-Constructed Tip-Based Dual Chemical Sensing by Tip-Enhanced Raman Spectroscopy for Diabetes Detection

Tip-enhanced Raman spectroscopy (TERS) is capable of probing specific molecular information with high sensitivity, but dual chemical sensing remains a challenge. Another major hindrance to TERS chemical detection in biosamples such as blood is the interference from the strong absorptions of biomolecules. Herein, we report the preparation of an organometallic-conjugated TERS tip. We demonstrate that organometallic chemistry can be perfectly coupled with TERS for dual-molecule sensing. The unique Raman signals generated by the organometallic compound circumvent signal interference from the biomolecules in blood, allowing the rapid analysis of two important molecules (glucose and thiol) in ultralow volume (50 nL) samples. This enabled a correlation between the thiol and glucose levels in the blood of nondiabetic and diabetic patients to be drawn.

Identification of Oxidative Stress in Red Blood Cells with Nanoscale Chemical Resolution by Infrared Nanospectroscopy

During their lifespan, Red blood cells (RBC), due to their inability to self-replicate, undergo an ageing degradation phenomenon. This pathway, both in vitro and in vivo, consists of a series of chemical and morphological modifications, which include deviation from the biconcave cellular shape, oxidative stress, membrane peroxidation, lipid content decrease and uncoupling of the membrane-skeleton from the lipid bilayer. Here, we use the capabilities of atomic force microscopy based infrared nanospectroscopy (AFM-IR) to study and correlate, with nanoscale resolution, the morphological and chemical modifications that occur during the natural degradation of RBCs at the subcellular level. By using the tip of an AFM to detect the photothermal expansion of RBCs, it is possible to obtain nearly two orders of magnitude higher spatial resolution IR spectra, and absorbance images than can be obtained on diffraction-limited commercial Fourier-transform Infrared (FT-IR) microscopes. Using this approach, we demonstrate that we can identify localized sites of oxidative stress and membrane peroxidation on individual RBC, before the occurrence of neat morphological changes in the cellular shape.

Nanoscale partitioning of paclitaxel in hybrid lipid-polymer membranes

Paclitaxel is a powerful drug against restenosis and many forms of cancer. However, its clinical application hinges on the ability to achieve suitable stabilized drug concentrations in an aqueous suspension while hindering drug crystallization. To engineer such formulations, it is imperative to understand paclitaxel's partitioning and crystallization within the carrier matrix. Lipid-polymer hybrid films have been recently shown to accommodate large paclitaxel loads and suppress crystallization. Additionally, such hybrid materials promote synergistic drug release compared to the pure constituents. Here, we leverage the composition sensitive photo-thermal induced resonance (PTIR) technique to study paclitaxel partitioning within hybrid films at the nanoscale. PTIR data reveal that paclitaxel nano-crystals segregate from lipid-only films but are well dispersed in polymer-only films. Remarkably, lipid-polymer hybrid films show enhanced partitioning of paclitaxel at the lipid-polymer phase boundaries, but still stifle crystallization, thus paving the way towards compositional and microstructural engineering of small-drug delivery systems.

Nanoscale Investigation into the Cellular Response of Glioblastoma Cells Exposed to Protons

Exposure to ionizing radiation can induce cellular defense mechanisms including cell activation and rapid proliferation prior to metastasis and in extreme cases can result in cell death. Herewith we apply infrared nano- and microspectroscopy combined with multidimensional data analysis to characterize the effect of ionizing radiation on single glioblastoma nuclei isolated from cells treated with 10 Gy of X-rays or 1 and 10 Gy of protons. We observed chromatin fragmentation related to the formation of apoptotic bodies following X-ray exposure. Following proton irradiation we detected evidence of a DNA conformational change (B-DNA to A-DNA transition) related to DNA repair and accompanied by an increase in protein content related to the synthesis of peptide enzymes involved in DNA repair. We also show that proton exposure can increase cholesterol and sterol ester synthesis, which are important lipids involved in the metastatic process changing the fluidity of the cellular membrane in preparation for rapid proliferation.