Fluorescence Assay for the Determination of d-Panthenol Based on Novel Ring-Fused 2-Pyridone Derivative

Panthenol Citrate Biomaterials Accelerate Wound Healing and Restore Tissue Integrity

Impaired wound healing is a common complication for diabetic patients and effective diabetic wound management remains a clinical challenge. Furthermore, a significant problem that contributes to patient morbidity is the suboptimal quality of healed skin, which often leads to reoccurring chronic skin wounds. Herein, a novel compound and biomaterial building block, panthenol citrate (PC), is developed. It has interesting fluorescence and absorbance properties, and it is shown that PC can be used in soluble form as a wash solution and as a hydrogel dressing to address impaired wound healing in diabetes. PC exhibits antioxidant, antibacterial, anti-inflammatory, and pro-angiogenic properties, and promotes keratinocyte and dermal fibroblast migration and proliferation. When applied in a splinted excisional wound diabetic rodent model, PC improves re-epithelialization, granulation tissue formation, and neovascularization. It also reduces inflammation and oxidative stress in the wound environment. Most importantly, it improves the regenerated tissue quality with enhanced mechanical strength and electrical properties. Therefore, PC could potentially improve wound care management for diabetic patients and play a beneficial role in other tissue regeneration applications.

The role of molecular fluorophores in the photoluminescence of carbon dots derived from citric acid: current state-of-the-art and future perspectives

Carbon dots (CDs), an emerging class of nanomaterials, have attracted considerable attention due to their intriguing photophysical properties. Despite their indisputable potential of utilization in many fascinating areas of research and life, some fundamental aspects concerning their structure and the origin of their photoluminescence (PL) properties still await clarification. The mechanism of PL emission of CDs is associated with their structure, which is dependent on the carbonization process. At the initial stages of CD synthesis via a bottom-up approach, molecular fluorophores are considered to dominate the optical characteristics of the resulting nanomaterials. In this review, the recent progress in the use of molecular state theory for explanation of the structure-property relationship in CDs is summarized. This review focuses exclusively on the molecular fluorophores existing in nanomaterials prepared from citric acid (CA) as one of the most frequent carbon sources reported for the bottom-up synthesis of CDs. Consequently, the most relevant transformations of CA and the history of molecular fluorophores derived from it are described, followed by an in-depth discussion on their relevance in understanding the specific photophysical properties of blue-, green-, and red-emitting CDs. Finally, the challenging issues and future perspectives of molecular state PL mechanism exploration in CDs are highlighted.

Nature of Linear Spectral Properties and Fast Electronic Relaxations in Green Fluorescent Pyrrolo[3,4-c]Pyridine Derivative

The electronic nature of 4-hydroxy-1H-pyrrolo[3,4-c]pyridine-1,3,6(2H,5H)-trione (HPPT) was comprehensively investigated in liquid media at room temperature using steady-state and time-resolved femtosecond transient absorption spectroscopic techniques. The analysis of the linear photophysical and photochemical parameters of HPPT, including steady-state absorption, fluorescence and excitation anisotropy spectra, along with the lifetimes of fluorescence emission and photodecomposition quantum yields, revealed the nature of its large Stokes shift, specific changes in the permanent dipole moments under electronic excitation, weak dipole transitions with partially anisotropic character, and high photostability. Transient absorption spectra of HPPT were obtained with femtosecond resolution and no characteristic solvate relaxation processes in protic (methanol) solvent were revealed. Efficient light amplification (gain) was observed in the fluorescence spectral range of HPPT, but no super-luminescence and lasing phenomena were detected. The electronic structure of HPPT was also analyzed with quantum-chemical calculations using a DFT/B3LYP method and good agreement with experimental data was shown. The development and investigation of new pyrrolo[3,4-c]pyridine derivatives are important due to their promising fluorescent properties and potential for use in physiological applications.

Fluorescence assay for the determination of glutathione based on a ring-fused 2-pyridone derivative in dietary supplements

Herein, a novel fluorescent method for the determination of GSH levels in aqueous solutions involving the utilization of citric acid as a derivatization reagent was developed. Therefore, the crucial parameters of the derivatization process were established from what has resulted in the development of a sensitive, reproducible, and accurate GSH assay. The method was validated, and its applicability in the characterization of the GSH concentration in dietary supplements concerning the selectivity in the determination of GSH over GSSG was both confirmed. The chemical structure of the new fluorophore 3-[(carboxymethyl)carbamoyl]-5-oxo-2,3-dihydro-5H-[1,3]thiazolo[3,2-a]pyridine-7-carboxylic acid - CTPC was elucidated using detailed NMR: one-dimensional (¹H, ¹³C), as well as two-dimensional NMR spectra (¹H-¹H COSY, ¹H-¹³C HSQC, ¹H-¹³C HMBC, ¹H-¹⁵N HSQC, ¹H-¹⁵N HMBC) experiments. Besides, the essential optical, biological and antioxidative properties of CTPC were investigated.