Infrared spectroscopy

Cell penetrating peptides (CPPs) are short sequences of amino acids that excel in
crossing the cellular membrane without inducing cytotoxicity Interest in these peptides
stem from their ability to be attached, and grant their penetrating properties to, a variety
of cargo In this work we have combined the application of Confocal Raman Microscopy
(CRM) and Atomic Force Microscopy for the first time to examine the interactions of
unlabeled Transportan (TP), one of the most well studied CPPs, with mammalian cells
CRM’s capability to discriminate control and treated cell groups was verified by principal
component analysis (PCA) and linear discriminant analysis (LDA) and was 93-100%
accurate We’ve determined that at a concentration of 20 μM TP enters cells through a
non-endocytotic mechanism, has a high affinity for the cytoplasm and membranes, and
results in a significant increase in cellular stiffness Our work provides the first direct
evidence of this cell-stiffening phenomenon SFTI-1, the smallest member of a bicyclic, cysteine rich class of CPPs, was
examined by CRM to determine the potential role of cyclic structure on cellular uptake
The peptide, along with monocyclic and linear analogs was heavy isotope labeled and
incubated with mammalian cells at numerous concentrations and timespans Our work is
the first SFTI-1 uptake study forgoing the use of fluorophore conjugates, which have
been linked to artificial cellular uptake We demonstrate herein the absence of any CRM
detectable uptake, providing the first evidence that SFTI-1 may not be a CPP
Finally, CRM was applied to the discrimination of normal and basal cell
carcinoma cells obtained from the same donor The use of patient matched cells avoids
the normal biochemical variations that exist among individuals, ensuring that
discrimination is based solely on the cell’s diseased state CRM spectra, analyzed by
PCA and LDA, were capable of spectral discrimination with 100% accuracy Major
differences in the cancerous cells were an increase in lipids and nucleic acids, and an
overall decrease in protein We also demonstrate an enhancement in Raman signal
through the use of an aluminum foil substrate, providing a practical approach for
measuring cells with thin morphologies

This study explores the application of two methods of spectroscopy; Near Infrared
spectroscopy (NIR) and Fourier transform spectroscopy (FTIR) as alternative approaches
for measuring glucocorticoid metabolites in chimpanzee feces. The goals of this study
were twofold: The first was to determine if cortisol can be identified within the NIR
and/or FTIR spectra of chimpanzee fecal hormone extract in ethanol solution. The second
objective was to determine the capability of NIR and FTIR to predict FGM
concentrations obtained using standard laboratory methods. Fecal glucocorticoid
concentrations measured by Enzyme Immunoassay were used as the reference data of
partial least square (PLS) regression of fecal extract NIR spectra and FTIR spectra. Low
accuracies (NIR: R2 = 0.152; FTIR: R2 = 0.199) were obtained from regression models
using data from both methods. Though this study did not successfully demonstrate the feasibility of using NIR and FTIR to qualify and quantify FGMs, it is likely not a
reflection of the capabilities of the technology, but rather of appropriate sample types and
preparation methods.

Reaction of Group IVB metallocene dichlorides with a monoaza dye yields a polymer in which the metal is bonded to a sulfonic and a hydroxyl group. The structure and bonding of the polymer was confirmed using infrared, mass spectrometry and 1H-NMR spectroscopy. Thermo and elemental analysis was used to confirm the presence of the metal. The stability of the polydye to the monomer unit was compared employing an argon laser in the visible region.

Cell penetrating peptides (CPPs) have drawn the attention of researchers due to their ability to internalize large cargos into cells including cancer cells. The mechanism(s) with which the peptides enter the cell, however, is/are not clear and full of controversy. The peptide conformations and their microenvironment in live cells had been unknown until the development of a technique developed in our lab. As a first demonstration of principle, penetratin, a 16-residue CPP derived from the Antennapedia homeodomain protein of Drosophila, was measured in single, living melanoma cells. Carbon-13 labeling of the Phe residue of penetratin was used to shift the intense aromatic ring-breathing vibrational mode from 1003 to 967 cm-1, thereby enabling the peptide to be traced in cells. Difference spectroscopy and principal components analysis (PCA) were used independently to resolve the Raman spectrum of the peptide from the background cellular Raman signals.