Silver nanoparticles and graphitic carbon through thermal decomposition of a silver/acetylenedicarboxylic salt

Synergistic effect of Silver-Nanodiamond composite as an efficient antibacterial agent against E. coli and S. aureus

Bacterial antimicrobial resistance (BAMR) seems to pose the greatest threat to public health, food safety, and agriculture in this century. The development of novel efficient antimicrobial agents to combat bacterial infections has become a global issue. Silver nanoparticles (Ag NPs) appeared as a feasible alternative to antibiotics. However, Ag NPs face cost, toxicity, and aggregation issues which limit their antibacterial activity. This work aims to stabilize Ag NPs with enhanced antimicrobial activity at comparatively lower Ag concentrations to prevent bacterial infections. For this purpose, the Ag core was covered with nanodiamonds (NDs). Ag-NDs composite have been synthesized by microplasma technique. TEM analysis confirmed the presence of both Ag and NDs in the Ag-NDs composite. A particle size (∼19 nm) was reported for Ag-NDs at the highest concentration as compared to Ag NPs (∼3 nm). The conduction band of the diamond acted as an extremely strong reducing agent for Ag NPs. The large surface area of NDs stabilized the Ag NPs. A redshift (∼400 nm-406 nm) in UV-visible spectra of the Ag-NDs composite indicated the formation of bigger-sized Ag NPs after incorporating NDs. XRD and LIBS analysis verified the increase in intensity of Ag-NPs by increasing ND concentration. The presence of functional groups including OH, CH, and Ag/Ag2O was confirmed by FTIR. Bacterial inhibition growth appeared to be a dose-dependent process. The minimum inhibition concentration value of Ag-NDs composite at the highest NDs concentration against E. coli (∼ 0.69 μg/ml) and S. aureus (∼44 μg/ml). This is the first study to report the smallest MIC for E. coli (<1 μg/ml). Ag-ND composites emerged to be more efficient than Ag NPs and preferred to be used against BAMR. The enhanced antibacterial activity of the Ag-NDs composite makes it a potential candidate for antibiotics, food products, and pesticides.

Fabricating gum polysaccharides based nano-composites for drug delivery uses via sustainable green approach

Recent advancements in development of natural polymer nono-composites led to exploration of potential of gum acacia (GA) and tragacanth gum (TG) for design of silver nanoparticles (AgNPs) impregnated grafted copolymers via green approach for use in drug delivery (DD). The formation of copolymers was confirmed by UV-Vis spectroscopy, TEM, SEM, AFM, XPS, XRD, FTIR,TGA and DSC. UV-Vis spectra indicated the formation of AgNPs using GA as reducing agent. TEM, SEM, XPS and XRD revealed impregnation of AgNPs inside the copolymeric network hydrogels. TGA inferred thermal stability of polymer enhanced by grafting and incorporation of AgNPs. The non-Fickian diffusion of antibiotic drug meropenem was revealed from drug encapsulated GA-TG-(AgNPs)-cl-poly(AAm) network which were also pH responsive and release profile was fitted in Korsmeyer-Peppas kinetic model. Sustained release was due to polymer-drug interaction. The polymer-blood interaction demonstrated biocompatible characteristics of polymer. Mucoadhesive property exhibited by copolymers because of supra-molecular interactions. Antimicrobial characteristics were shown by copolymers against bacteria S. flexneri, P. auroginosa, and B. cereus.

Insights of the formation mechanism of nanostructured titanium oxide polymorphs from different macromolecular metal-complex precursors

The insight into the mechanism of the unprecedented formation of pure anatase TiO2 from the macromolecular (Chitosan)•(TiOSO4)n precursor has been investigated using micro Raman spectroscopy, Scanning Electron Microscopy (SEM) and thermogravimetric/differential thermal analysis (TGA/DTA). The formation of a graphitic film was observed upon annealing of the macromolecular precursor, reaching a maximum at about 500 °C due to decomposition of the polymeric chain of the Chitosan and (PS-co-4-PVP) polymers. The proposed mechanism is the nucleation and growth of TiO2 nanoparticles over this graphitic substrate. SEM and Raman measurements confirm the formation of TiO2 anatase around 400 °C. The observation of an exothermic peak around 260 °C in the TGA/DTA measurements confirms the decomposition of carbon chains to form graphite. Another exothermic peak around 560 °C corresponds to the loss of additional carbonaceous residues.

Metal Nanoparticles: Thermal Decomposition, Biomedicinal Applications to Cancer Treatment, and Future Perspectives

Monodispersed forms of metal nanoparticles are significant to overcome frightening threat of cancer. This review examined pragmatically thermal decomposition as one of the best ways to synthesize monodispersed metal nanoparticles which are stable and of small particle sizes. Controlled morphology for delivery of anticancer agent to specific cells can also be obtained with thermal decomposition. In addition to thermal decomposition, the study also looked into processes of characterization techniques, biological evaluation, toxicity of nanoparticles, and future perspectives.