Phenylalanine gold nanoclusters as sensing platform for π-π interfering molecules: a case study of iodide

The photo-physical properties of metal nano clusters are sensitive to their surrounding medium. Fluorescence enhancement, quenching, and changes in the emitted photon properties are usual events in the sensing applications using these nano materials. Combining this sensitivity with unique properties of self-assembled structures opens new opportunities for sensing applications. Here, we synthesized gold nanoclusters by utilizing phenylalanine amino acid as both capping and reducing molecule. Phenylalanine is able to self-assemble to rod-shaped nano structure in which the π-π interaction between the aromatic rings is a major stabilizing force. Any substance as iodide anion or molecule that is able to weaken this interaction influence the fluorescence of metal nano-clusters. Since the building blocks of the self-assembled structure are made through the reaction of gold ions and phenylalanine, the oxidized products and their effect of sensing features are explored.

Resveratrol: A Vital Therapeutic Agent with Multiple Health Benefits

Resveratrol (RSV), the most effective stilbene phytoalexin synthesized naturally or induced in plants as part of their defense mechanism, is a key component of natural phenolic compounds and is being considered as a treatment option for a variety of diseases. RSV was discovered in the skin of red grapes, mulberries, peanuts, pines, and Polygonum cuspidatum weed root extracts. It was first extracted from white hellebore (Veratrum grandiflorum O. Loes) roots in 1940, then from Polygonum cuspidatum roots in 1963. However, RSV's use as a drug is limited due to its initial conformational strength and poor stability. The research focused on a set of RSV biological activity data. RSV has been the subject of growing concern, despite its wide range of biological and therapeutic applications. According to the literature, RSV has antioxidant, anti-cancer, cardioprotective, neuroprotective, anti- inflammatory, anti-microbial, immunomodulatory, and radioprotective properties. The current analysis summarized biological applications of RSV, their mechanisms of action, and recent scientific development in the area of their delivery. It is possible to infer that RSV has many effects on infected cells' cellular functions.

Dominant Carbons in trans- and cis-Resveratrol Isomerization

A comprehensive analysis for isomerization of geometric isomers in the case of resveratrol (R) has been presented. As an important red wine molecule, only one geometric isomer of resveratrol, i.e., trans-R rather than cis-R, is primarily associated with health benefit. In the present study, density function theory (DFT) provides accurate descriptions of isomerization of resveratrol. The nearly planar trans-R forms a relatively rigid and less flexible conjugate network, but the nonplanar cis-R favors a more flexible structure with steric through space interaction. The calculated carbon nuclear magnetic resonance (NMR) chemical shift indicates that all carbons are different in the isomers; it further reveals that four carbon sites, i.e., C₍₆₎, C₍₈₎═C₍₉₎, and C₍₁₁₎, have a significant response to the geometric isomerization. Here C₍₆₎ is related to the steric effect in cis-R, whereas C₍₁₁₎ may indicate the isomerization proton transfer on C₍₉₎ linking with the resorcinol ring. The excess orbital energy spectrum (EOES) confirms the NMR "bridge of interest" carbons and reveals that five valence orbitals of 34a, 35a, 46a, 55a, and 60a respond to the isomerization most significantly. The highest occupied molecular orbital (HOMO), 60a, of the isomer pair is further studied using dual space analysis (DSA) for its orbital momentum distributions, which exhibit p-electron dominance for trans-R but hybridized sp-electron dominance for cis-R. Finally, energy decomposition analysis (EDA) highlights that trans-R is preferred over cis-R by -4.35 kcal·mol^-1, due to small electrostatic energy enhancement of the attractive orbital energy with respect to the Pauli repulsive energy.