Photodynamic antimicrobial activity of benzimidazole substituted phthalocyanine when conjugated to Nitrogen Doped Graphene Quantum Dots against Staphylococcus aureus

Trinuclear ruthenium(II) polypyridyl complexes: Evaluation as photosensitizers for enhanced cervical cancer treatment

Trinuclear ruthenium(II) polypyridyl complexes anchored to benzimidazole-triazine / trisamine scaffolds were investigated as photosensitizers for photodynamic therapy. The trinuclear complexes were noted to produce a significant amount of singlet oxygen in both DMF and aqueous media, are photostable and show appreciable emission quantum yields (ɸem). In our experimental setting, despite the moderate phototoxic activity in the HeLa cervical cancer cell line, the phototoxic indices (PI) of the trinuclear complexes are superior relative to the PIs of a clinically approved photosensitizer, Photofrin®, and the pro-drug 5-aminolevulinic acid (PI: >7 relative to PI: >1 and PI: 4.4 for 5-aminolevulinic acid and Photofrin®, respectively). Furthermore, the ruthenium complexes were noted to show appreciable long-term cytotoxicity upon light irradiation in HeLa cells in a concentration-dependent manner. Consequently, this long-term activity of the ruthenium(II) polypyridyl complexes embodies their ability to reduce the probability of the recurrence of cervical cancer. Taken together, this presents a strong motivation for the development of polymetallic complexes as anticancer agents.

A novel fluorescent strategy for Golgi protein 73 determination based on aptamer/nitrogen-doped graphene quantum dots/molybdenum disulfide @ reduced graphene oxide nanosheets

The effective detection of biomarkers associated with hepatocellular carcinoma (HCC) is of great importance. Golgi protein 73 (GP73), a serum biomarker of HCC, has better diagnostic value than Alpha-fetoprotein (AFP) has been reported. In this paper, highly accurate fluorescence sensing platform for detecting GP73 was constructed based on fluorescence resonance energy transfer (FRET), in which nitrogen-doped graphene quantum dots (NGQDs) labelling with GP73 aptamer (GP73_Apt) was used as fluorescence probe, and molybdenum disulfide @ reduced graphene oxide (MoS₂@RGO) nanosheets was used as fluorescent receptors. MoS₂@RGO nanosheets can quench the fluorescence of NGQDs-GP73_Apt owing to FRET mechanisms. In the presence of GP73, the NGQDs-GP73_Apt specifically bound with GP73 to from the deployable structures, making NGQDs-GP73_Apt far away from MoS₂@RGO nanosheets, blocking the FRET process, resulting in fluorescence recovery of NGQDs-GP73_Apt. Under optimal conditions, the recovery intensity of fluorescence in the detection system is linearly related to the concentration of GP73 in the range of 5 ng/mL - 100 ng/mL and the limit of detection is 4.54 ng/mL (S/N = 3). Moreover, detection of GP73 was performed in human serum samples with good recovery (97.21-100.83%). This platform provides a feasible method for the early diagnosis of HCC, and can be easily extended to the detection of other biomarkers.

Photosensitization of fucoxanthin-graphene complexes: A computational approach

Photosensitization of fucoxanthin-graphene (FX-GR) complexes were investigated in this work for detecting their roles of irradiating energy absorptions. To this aim, density functional theory (DFT computational approach as employed to obtain the optimized structures and their corresponding molecular orbital features. Both of original linear models of FX and its broken models, LFX and RFX, were investigated for attaching to a brigading GR molecular model. In this regard, the models were optimized to obtain the minimized energy configurations, in which for double-attachment of FG to the GR coroner atoms, Cis and Trans configurations were obtained for the FX-GR complex models. Based on the obtained achievements of molecular orbitals photosensitization features, the models were varied by the absorbed wavelengths making them suitable for various applications. In this regard, both of shorter and longer irradiated wavelengths were applicable for the purpose.

DFT investigation of BN, AlN, and SiC fullerene sensors for arsine gas detection and removal

 Quantum chemical density functional theory (DFT) calculations were performed to investigate the adsorption of arsine (AsH3) gaseous substance at the surface of representative models of boron nitride (B16N16), aluminum nitride (Al16N16), and silicon carbide (Si16C16) fullerene-like nanocages. The results indicated that the adsorption processes of AsH3 could be taken place by each of B16N16, Al16N16, and Si16C16 nanocages. Moreover, the electronic molecular orbital properties indicated that the electrical conductivity of nanocages were changed after the adsorption processes enabling them to be used for sensor applications. To analyze the strength of interacting models, the quantum theory of atoms in molecules (QTAIM) was employed. As a typical achievement of this work, it could be mentioned that the investigated Si16C16 fullerene-like nanocage could work as a suitable adsorbent for the AsH3 gaseous substance proposing gas-sensor role for the Si16C16 fullerene-like nanocage.

Investigating a promising iron-doped graphene sensor for SO2 gas: DFT calculations and QTAIM analysis

Examination of a promising iron-doped graphene (FG) sensor for the sulfur oxide (SO2) toxic gas was done in this work at the molecular and atomic scales of density functional theory (DFT). The models were stabilized by performing optimization calculations and their electronic features were evaluated. Two models were obtained by relaxing each of the O or S atoms towards the Fe-doped region of surface. Energy values indicated higher strength for formation of the O@FG model in comparison with the S@FG model. The evaluated quantities and qualities of electronic molecular orbitals indicated the effects of occurrence of adsorption processes on the electronic conductivity property of FG as a required feature of a sensor material. As a consequence, the idea of proposing the investigated FG as a promising sensor of the hazardous SO2 gas was affirmed in this work based on the obtained structural and electronic features.

Investigating fullerene-oxide nanostructure as an adsorbent of ammonia: Complexation efficiency by density functional theory

A model of OC20 fullerene-oxide (FO) was investigated in this work for adsorbing the ammonia (NH3) substance by the hypothesis of formations of bimolecular complexes of the two substances. To affirm such hypothesis, the models of singular NH3 and FO were optimized to reach the minimized energy structures and all possibilities of their interactions configurations were examined. As a consequence, three NH3@FO bimolecular complex models were obtained for reaching the point of complex formations. Details of interactions indicated both direct and indirect contributions of the oxidized region of FO to interactions with both H and N atomic sites of NH3. In this regard, CPLX3 with two types of H. . . O and N. . . C interactions was seen to be at the highest strength of adsorption and complex formation in comparison with CPLX1 and CPLX2 models including only one interaction of each of H. . . O and N. . . C type, respectively. Moreover, the obtained electronic molecular orbital features revealed the sensor function of FO material versus the NH3 substance. As a consequence, the hypothesis of NH3@FO complexes formation was affirmed with two proposed functions of removal and detection for the investigated FO material. All results of this work were obtained by details through performing density functional theory (DFT) calculations.

New rout for synthesizing triammonium citrate crystal with unique crystallography and its application in synthesizing nitrogen doped graphene quantum dot

Triammonium citrate crystal (TAC) has many applications in food, pharmaceutical, agricultural and other industries. In this work, TAC crystals were synthesized using a new method and with the least use of materials and tools. This crystal has a unique structure and special and new angles and bonds that were identified by crystallography. This crystal was then used to synthesize nitrogen- doped graphene quantum dot (N-GQD) with hydrothermal method. Synthesized N-GQD has particular morphology, fluorescence and viscosity. Compared with other nitrogen compounds necessary for N-GQDs synthesis, ammonia is much more suitable due to its low toxicity and stability. Synthesized TAC and N-GQD were identified by FT-IR, XRD, TGA, EDS, SEM, crystallography and fluorescence.

Investigating drug delivery of 5-fluorouracil by assistance of an iron-modified graphene scaffold: Computational studies

This computational work was performed to investigate drug delivery of 5-fluorouracil (FU) anti-cancer by assistance of an iron(Fe)-modified graphene (G) scaffold. The models were optimized to reach the minimized energy structures in both of singular and bimolecular models. Two models of FU@G complex were obtained including O2@G and O4@G by relaxation of FU through O2 and O4 atoms towards the Fe-atom region of G surface. The obtained results of energies indicated a higher stability and strength for the O2@G model in comparison with the O4@G model. The quantitative and qualitative features of electronic molecular orbitals indicated the investigated G surface could work as a carrier of FU by reducing the unwanted side effects and also playing the sensor role. As a final remark of this work, the investigated G model could be proposed for employing in the targeted drug delivery of FU in both of carrier and sensor agents.

Electronic and structural features of uranium-doped graphene: DFT study

Electronic and structural features of uranium-doped models of graphene (UG) were investigated in this work by employing the density functional theory (DFT) approach. Three sizes of models were investigated based on the numbers of surrounding layers around the central U-doped region including UG1, UG2, and UG3. In this regard, stabilized structures were obtained and their electronic molecular orbital features were evaluated, accordingly. The results indicated that the stabilized structures could be obtained, in which their electronic features are indeed size-dependent. The conductivity feature was expected at a higher level for the UG3 model whereas that of the UG1 model was at a lower level. Energy levels of the highest occupied and the lowest unoccupied molecular orbitals (HOMO and LUMO) were indeed the evidence of such achievement for electronic conductivity features. As a consequence, the model size of UG could determine its electronic feature providing it for specified applications.

Antimicrobial Photodynamic Therapy: Latest Developments with a Focus on Combinatory Strategies

Antimicrobial photodynamic therapy (aPDT) has become a fundamental tool in modern therapeutics, notably due to the expanding versatility of photosensitizers (PSs) and the numerous possibilities to combine aPDT with other antimicrobial treatments to combat localized infections. After revisiting the basic principles of aPDT, this review first highlights the current state of the art of curative or preventive aPDT applications with relevant clinical trials. In addition, the most recent developments in photochemistry and photophysics as well as advanced carrier systems in the context of aPDT are provided, with a focus on the latest generations of efficient and versatile PSs and the progress towards hybrid-multicomponent systems. In particular, deeper insight into combinatory aPDT approaches is afforded, involving non-radiative or other light-based modalities. Selected aPDT perspectives are outlined, pointing out new strategies to target and treat microorganisms. Finally, the review works out the evolution of the conceptually simple PDT methodology towards a much more sophisticated, integrated, and innovative technology as an important element of potent antimicrobial strategies.