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Background: Nowadays, a new technique such as photodynamic therapy (PDT) is used to achieve effective root canal disinfection and eliminate Enterococcus faecalis as the most prevalent species associated with secondary endodontic infections and treatment failures. Employment of an optimized nontoxic photosensitizer (PS) such as indocyanine green (ICG) is a crucial part of this technique; the current study aimed at improving ICG photodynamic properties through conjugation of ICG into nano-graphene oxide (nGO) as a new PS, to evaluate the antimicrobial effects of nGO/ICG against E. faecalis. Methods:The nGO was synthesized based on the modified Hummer method and then, direct loading of ICG onto its surface. The nGO formation was evaluated using the scanning electron microscope (SEM). The antimicrobial effect of nGO/ICG-PDT against E. faecalis was assessed by counting colony forming units (CFUs). Results and Conclusion:The SEM analysis confirmed successful synthesis of nGO. The nGO/ICG-PDT at an incorporated concentration of 400 µg/mL ICG with irradiation at an energy density of 31.2 J/cm 2 showed significant reduction in the number of E. faecalis higher than PDT based on ICG (1000 µg/mL) (P < 0.05). Since nGO-ICG-PDT showed a significant reduction in the count of E. faecalis at low concentration of ICG (400 µg/mL), it could be proposed as a new approach to treat endodontic infections, alone or in combination with conventional root canal treatment.

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A novel series of coumarin derivatives linked to the N-benzyl triazole group were synthesized and evaluated against 15-lipoxygenase (15-LOX), and acetyl- and butyrylcholinesterase (AChE and BuChE) to find the most potent derivative against Alzheimer’s disease (AD). Most of the compounds showed weak to moderate activity against ChEs. Among the most active BuChE and 15-LOX inhibitors, 8l and 8n exhibited an excellent neuroprotective effect, higher than the standard drug (quercetin) on the PC12 cell model injured by H2O2 and significantly reduced aggregation of amyloid Aβ1-42, with potencies of 1.44 and 1.79 times higher than donepezil, respectively. Compound 8l also showed more activity than butylated hydroxytoluene (BHT) as the reference antioxidant agent in reducing the levels of H2O2 activated by amyloid β in BV2 microglial cells. Kinetic and ligand–enzyme docking studies were also performed for better understanding of the mode of interaction between the best BuChE inhibitor and the enzyme. Considering the acceptable BuChE and 15-LOX inhibition activities as well as significant neuroprotection, and anti-amyloid aggregation activities, 8l and 8n could be considered as potential MTDLs for further modification and studies against AD.

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Antimicrobial photodynamic therapy (aPDT) is a high potential strategy for the treatment of microbial infections in endodontics. In this study, a novel antibacterial agent was designed and prepared based on the two morphologies of zinc oxide nanomaterials (NMs) as ZnO nanosphere (ZnOS) and ZnO nanorod (ZnOR). Their surfaces were coated with carnosine (CAR)-functionalized polycyclodextrin (ZnO@PCD-CAR) for higher payload of curcumin (CUR) as a photosensitizer (PS). This system was characterized using FT-IR, XRD, TGA, FE-SEM, zeta potential analysis and UV-visible spectroscopy. The colony forming unit (CFU) assay was carried out to evaluate the antimicrobial properties of the nanoformulations againts Enterococcus faecalis (E. Faecalis). The target products (ZnOS@PCD-CAR/CUR and ZnOR@PCD-CAR/CUR) exhibited a light stability approximately by 2.9 and 2.8 fold, respectively, higher than the free CUR. Compared to the bare CUR, these materials indicated more stability againts pH variations. ZnOS@PCD-CAR/CUR and ZnOR@PCD-CAR/CUR NMs-mediated aPDT, significantly declined the count of E. Faecalis strains about 1.5 and 2 log (P < 0.05). Due to the high CUR loading, proper stability and significant inhibitory effects against E. Faecalis, ZnO@PCD-CAR/CUR could be considered as a promising antimicrobial agent in aPDT for efficient treatment of root canal infections.