Non-invasive and rapid diagnosis of type 2 diabetes mellitus based on the analysis of hair by front-face fluorescence spectroscopy

Rapid and early detection of pathologies for screening purposes is not always easy with traditional methods. New low-cost optical techniques that are suitable for preventive detection and, more specifically, for developing countries must be developed. The objective of this work is to propose UV-VIS fluorescence of hair as a promising technique for a simple and rapid preliminary diagnosis of type II diabetes. In this work, we analyzed 130 hair samples taken from volunteers of different ages at the Habib Thameur Hospital in Tunis, Tunisia. These samples were analyzed clinically beforehand, and 50 were classified as healthy acting as a control, 24 were classified as low-level diabetics with a glycated hemoglobin A1C (HbA1c) <7%, and the other 56 were classified as high-level diabetics having an HbA1c >7%. The fluorescence of the patients' hair led to several interesting results. Indeed, a clear discrimination was obtained not only between the healthy and patients with a disease, but also a discrimination between diabetics with low levels and high levels or diabetics with and without complication. Also, a strong correlation between fluorescence spectra and glycated HbA1c for the diabetic population was clearly established. A linear discriminant analysis shows that it is possible to predict the status of test patients after having trained a fraction of the population. All these results show the ability of the front-face fluorescence (FFF) technique to detect disease and predict advanced states simply by capturing the fluorescence of the hair illuminated by a single LED. This work shows for the first time, to our knowledge, the capability of the FFF technique on hair samples for the diagnosis of diabetes.

New insights into the photoswitching mechanisms of normal dithienylethenes

The photoswitching and competitive processes of the referent photochromic diarylethene derivative 1,2-bis(2,4-dimethyl-5-phenyl-3-thienyl)perfluorocyclopentene (DTE) and a novel bridged analog DTE-m5 have been investigated by state-of-the-art TD-DFT calculations and ultrafast spectroscopy supported by advanced chemometric data treatments. Focusing on DTE, the overall deactivation pathway of both antiparallel (AP) and parallel (P) conformers of the open form (OF) (1 : 1 in solution) has been resolved and rationalized starting from the Franck-Condon (FC) region to the ground state recovery. For the photo-excited P conformer, after ultrafast relaxation (∼200 fs) towards the S₁ relaxed state, an expected ISC occurred (55 ps) to produce a triplet state, ³P, the latter relaxing within 2.5 μs. Concerning the AP conformer, the photocyclization reaction is reported to proceed immediately (100 fs) starting from the FC region while the relaxed singlet state is populated in parallel. For the first time, we discovered that the latter state evolves through an unexpected ISC process (1 ps) giving rise to a second triplet state,³AP. For DTE-m5, by slightly constraining the molecule with the bridge, this triplet becomes reactive and participates in the formation of 10% of closed form (CF) probably through an adiabatic mechanism. Concerning the photoreversion, in accordance with the literature, we report on a two-step process, a 190 fs vibrational relaxation followed by a 6 ps ring-opening reaction. For the overall species at the singlet or triplet manifold, the use of advanced MCR-ALS allows us to obtain specific spectral signatures. This study is therefore a new step within the comprehension of DTE photochemistry.

Photodissociation of the CH3O and CH3S radical molecules: an ab initio electronic structure study

The electronic states and the spin-orbit couplings between them involved in the photodissociation process of the radical molecules CH₃X, CH₃X → CH₃ + X (X = O, S), taking place after the Ã(²A₁) ← X[combining tilde](²E) transition, have been investigated using highly correlated ab initio techniques. A two-dimensional representation of both the potential-energy surfaces (PESs) and the couplings is generated. This description includes the C-X dissociative mode and the CH₃ umbrella mode. Spin-orbit effects are found to play a relevant role in the shape of the excited state potential-energy surfaces, particularly in the CH₃S case where the spin-orbit couplings are more than twice more intense than in CH₃O. The potential surfaces and couplings reported here for the present set of electronic states allow for the first complete description of the above photodissociation process. The different photodissociation mechanisms are analyzed and discussed in light of the results obtained.

Rotational Excitation of the CP(Χ2Σ+) Open Shell Molecule Due to Collision with He(1S)

Phosphorus bearing molecules have been discovered in the circumstellar and interstellar media. Modeling their abundance accurately requires computations of rate coefficients induced by collision with He and H₂ (i.e., the most abundant gaseous components). These calculations may be carried out by first determining highly accurate potential energy surface (PES) and cross sections. In this paper, we present the first PES of the CP(X²Σ⁺)-He(¹S) van der Waals collisional complex. The ab initio interaction potential was performed using the explicitly correlated restricted coupled cluster approach with simple, double, and perturbative triple excitation (RCCSD(T)-F12) in connection with the augmented-correlation consistent-polarized valence triple-ζ Gaussian basis set (aug-cc-pVTZ). The potential presents two minima of -18.62 cm^-1 and -18.72 cm^-1. From the PES obtained, we have computed state-to-state excitation cross sections of CP due to collision with He for energies up to 500 cm^-1. Rotational transitions involving the fine-structure levels of the CP molecule were treated with a recoupling technique based on the scattering matrix calculated with the exact quantum mechanical close coupling method. Discussions on the propensity rules between the fine-structure levels were made and we found that the Δj = ΔN transitions are favored with respect to the Δj ≠ ΔN ones. The data presented in this paper may have a great impact on the accurate determination of the CP abundance in space.

Weak intramolecular interaction effects on the torsional spectra of ethylene glycol, an astrophysical species

An elaborate variational procedure of reduced dimensionality based on explicitly correlated coupled clusters calculations is applied to understand the far infrared spectrum of ethylene-glycol, an astrophysical species. This molecule can be classified in the double molecular symmetry group G8 and displays nine stable conformers, gauche and trans. In the gauche region, the effect of the potential energy surface anisotropy due to the formation of intramolecular hydrogen bonds is relevant. For the primary conformer, stabilized by a hydrogen bond, the ground vibrational state rotational constants are computed to be A0 = 15 369.57 MHz, B0 = 5579.87 MHz, and C0 = 4610.02 MHz corresponding to differences of 6.3 MHz, 7.2 MHz, and 3.5 MHz from the experimental parameters. Ethylene glycol displays very low torsional energy levels whose classification is not straightforward and requires a detailed analysis of the torsional wavefunctions. Tunneling splittings are significant and unpredictable due to the anisotropy of the potential energy surface PES. The ground vibrational state splits into 16 sublevels separated ∼142 cm(-1). The splitting of the "G1 sublevels" was calculated to be ∼0.26 cm(-1) in very good agreement with the experimental data (0.2 cm(-1) = 6.95 MHz). Transitions corresponding to the three internal rotation modes allow assignment of previously observed Q branches. Band patterns, calculated between 362.3 cm(-1) and 375.2 cm(-1), 504 cm(-1) and 517 cm(-1), and 223.3 cm(-1) and 224.1 cm(-1), that correspond to the tunnelling components of the v21 fundamental (v21 = OH-torsional mode), are assigned to the prominent experimental Q branches.

Vibrational Analysis of Amino Acids and Short Peptides in Hydrated Media. I. L-glycine and L-leucine

Raman scattering and Fourier-transform infrared (FT-IR) attenuated transmission reflectance (ATR) spectra of two alpha-amino acids (alpha-AAs), i.e., glycine and leucine, were measured in H2O and D2O (at neutral pH and pD). This series of observed vibrational data gave us the opportunity to analyze vibrational features of both AAs in hydrated media by density functional theory (DFT) calculations at the B3LYP/6-31++G* level. Harmonic vibrational modes calculated after geometry optimization on the clusters containing each AA and 12 surrounding water molecules, which represent primary models for hydration scheme of amino acids, allowed us to assign the main observed peaks.