Theoretical determination of two-photon absorption in biologically relevant pterin derivatives

Abstract

Given the prevalence of fluorescence spectroscopy in biological systems, and the prevalence of pterin derivatives throughout biological systems, presented here is an assessment of the two-photon absorption spectroscopy as it...

Determination of two-photon absorption in nucleobase analogues: a QR-DFT perspective

“…such that is the photon energy in eV and Γ is a broadening factor of 0.1 eV [113]; while uncertainty in the broadening factor can create an argument of the use of values larger, or smaller, by a factor of 2, the value chosen here is consistent with previous work [35,114,115] and in the prediction of the two-photon line shape of a number of other molecules [113,[116][117][118][119]. is the fine line constant, and the transition strength ( TP ) is given by [102]:…”

“…The probes created from these analogues (Fig. 2) can be considered to occupy one of a number of categories, ranging from: (i) those closely resembling the native bases they aim to replace to maintain the -stacking and hydrogen bonding characteristics, such as 2-amino-purine (2AP) [30,34]; (ii) molecules employing pteridine moieties [35], as seen with 6-MI [36] and 6MAP [37], which have seen use as highly fluorescent analogues for the purine bases (Fig. 1); (iii) bases which have been extended to include a conjugated, primarily aromatic, moiety such as that observed in 6AzaO and 6AzaS [33]; (iv) structures in which fluorescently active aromatic moieties are linked directly to the native base, as observed in the adenine analogues, pA [38], qA, qAN1, and qAnitro [39][40][41], the cytosine analogues tC O [42], tC [30,43] and DMA C [44], as well as the thymine analogue diox T [45].…”

Photoactivation of Chemotherapeutic Agents with Cerenkov Radiation for Chemo-Photodynamic Therapy

“…Figure shows that MTX is a molecule like folic acid composed of a diamino-pterin ring bound to a p- amino benzoyl moiety linked, in turn, to glutamic acid. Under the action of UV–vis light, it dissociates into p -aminobenzoyl glutamic acid and 2,4-diamino-6-formylpterin, which is highly fluorescent. , The degradation of MTX by the action of the UV–vis light can be monitored by the degradation of its 360 nm absorption band , or by the increase in the 470 nm emission band of pterin . PTX, on the other hand, also shown in Figure , is a tetracyclic diterpenoid with a very complex structure in which a hydrocarbon skeleton formed by three cycles of six, eight, and six polysubstituted with four methyls and eight oxygenated functions stands out.…”

“…Since MTX has PS-like properties, the decrease in absorbance (Figure C) is most likely due to the interaction of the CR of 18 F-FDG with the pterin group of MTX to produce 1 O 2 , one of the main causes of PS photobleaching . Pterin groups easily form 1 O 2 in aerobic environments …”

“…26 Pterin groups easily form 1 O 2 in aerobic environments. 20 The analysis of the values obtained at each point (Figure 3D) reveals that the absorbance value at 250 μCi (9.25 MBq) of 18 F-FDG (absorbance = 0.269) is part of the confidence interval of the first point (0.261−0.297), which corresponds to 0 μCi of 18 F-FDG. This indicates that it cannot be affirmed that a significant change in the absorbance of the MTX has occurred.…”