Biosynthesized δ-Bi2O3 Nanoparticles from Crinum viviparum Flower Extract for Photocatalytic Dye Degradation and Molecular Docking

Bioinspired delta-bismuth oxide nanoparticles (δ-Bi₂O₃ NPs) have been synthesized using a greener reducing agent and surfactant via co-precipitation method. The originality of this work is the use of Crinum viviparum flower extract for the first time for the fabrication of NPs, which were further calcined at 800 °C to obtain δ-Bi₂O₃ NPs. Physicochemical studies such as FTIR spectroscopy and XPS confirmed the formation of Bi₂O₃ NPs, whereas XRD and Raman verified the formation of the cubic delta (δ) phase of Bi₂O₃ NPs. However, HRTEM revealed the spherical shape with diameter 10-20 nm, while BET studies expose mesoporous nature with a surface area of 71 m²/gm. The band gap for δ-Bi₂O₃ NPs was estimated to be 3.45 eV, which ensured δ-Bi₂O₃ to be a promising photocatalyst under visible-light irradiation. Therefore, based on the results of physicochemical studies, the bioinspired δ-Bi₂O₃ NPs were explored as active photocatalysts for the degradation of toxic dyes, viz., Thymol blue (TB) and Congo red (CR) under visible-light irradiation. The study showed 98.26% degradation of TB in 40 min and 69.67% degradation of CR in 80 min by δ-Bi₂O₃ NPs. The photogenerated holes and electrons were found responsible for this enhancement. Furthermore, molecular docking investigations were also performed for δ-Bi₂O₃ NPs to understand its biological function as New Delhi metallo-β-lactamase 1 (NDM-1) [PDB ID 5XP9] enzyme inhibitor, and studies revealed good interaction with various amino acid residues and found good hydrogen bonding with a fine pose energy of -3.851 kcal/mole.

Biogenic Synthesis of Metal/Metal Oxide Nanostructured Materials

Nanotechnology is an emerging outlet of the nanoscience in which the atoms are encompassed in nanoscale dimensions and come to be more receptive compared with their distinctive counterparts. Recently, the utilization of synthetic designs and physicochemical approaches have received special attention; nevertheless, the generation of noxious impressions on the eco-system have raised serious concerns of the scientific community worldwide. Presently, environmentfriendly green synthesis routes are promising venues for the arrangement of metal/metal oxide (M/MO) nanostructured materials by using plants and their corresponding alliances. This revolution is predominantly recompensing as far as the reduction of toxic emissions and wastes is concerned. Accordingly, materials scientists have adopted various renewable naturally occurring eco-friendly materials, and biogenic processes to fabricate the functional M/MO nanostructured materials. The current review article recapitulates and assimilates the present state of knowledge on different strategies for biogenic fabrication of M/MO nanostructured materials. Moreover, their diverse applications are summarized and discussed.

Bioinspired Reduced Graphene Oxide Based Nanohybrids for Photocatalysis and Antibacterial Applications

Ultra-thin graphene has been receiving a spacious significance in the diverse sections of material science, owing to its exceptional physicochemical and thermo-mechanical characteristics. Currently, the fabrication of high-grade graphene in an economical target and green procedures area is a massive concern. Among the diverse techniques, chemical-mediated fabrication is believed to be the finest process, since it is simple, scalable, and low-priced, however, therein involved noxious or hazardous chemical reducers to produce the functional graphene-based nanocomposites (NCs). Hence, globally scientists are continuously endeavoring to adopt the bioinspired procedures to manufacture the functional reduced graphene oxide (rGO) and reduced graphene oxide-metal/metal oxide (rGO-M/MO) NCs. Hence, keeping this issue in our mind, the present review article summarizes and integrates the current state of knowledge on diverse strategies for bioinspired fabrication of rGO and rGO-M/MO NCs and their photocatalytic, antibacterial, and cytotoxicity assessments.

Metal/Metal Oxide Nanoparticles: Toxicity, Applications, and Future Prospects

The ever-growing resistance of pathogens to antibiotics and crop disease due to pest has triggered severe health concerns in recent years. Consequently, there is a need of powerful and protective materials for the eradication of diseases. Metal/metal oxide nanoparticles (M/MO NPs) are powerful agents due to their therapeutic effects in microbial infections. In this context, the present review article discusses the toxicity, fate, effects and applications of M/MO NPs. This review starts with an introduction, followed by toxicity aspects, antibacterial and testing methods and mechanism. In addition, discussion on the impact of different M/MO NPs and their characteristics such as size, shape, particle dissolution on their induced toxicity on food and plants, as well as applications in pesticides. Finally, prospective on current and future issues are presented.

Mesoporous Octahedron-Shaped Tricobalt Tetroxide Nanoparticles for Photocatalytic Degradation of Toxic Dyes

The present article reports a facile approach to fabrication of mesoporous octahedron-shaped tricobalt tetroxide nanoparticles (Co₃O₄ NPs) with a very narrow size distribution for eco-friendly remediation of toxic dyes. Co₃O₄ NPs were fabricated by a sol-gel process using cobalt chloride hexahydrate (CoCl₂·6H₂O) and monosodium succinate (C₄H₅O₄Na) as a chelating/structure-directing agent and sodium dodecyl sulfate as a surfactant. Moreover, the phase structure, elemental composition, and thermal and morphological facets of Co₃O₄ NPs were investigated using XRD, FT-IR, EDS, Raman, XPS, TGA, SEM, and TEM techniques. The face-centered cubic spinel crystalline structure of the Co₃O₄ NPs was confirmed by XRD and SEM, and TEM analysis revealed their octahedron morphology with a smooth surface. Moreover, the narrow pore size distribution and the mesoporous nature of the Co₃O₄ NPs were confirmed by Brunauer-Emmett-Teller measurements. The photocatalytic activity of Co₃O₄ NPs for degradation of methyl red (MR), Eriochrome Black-T (EBT), bromophenol blue (BPB), and malachite green (MG) was examined under visible light irradiation, and the kinetics of the dye degradation was pseudo-zero-order with the rate constant in the order of MR > EBT > MG > BPB. Furthermore, the mechanism of photo-disintegration mechanism of the dye was examined by a scavenging test using liquid chromatography-mass chromatography, and its excellent photodegradation activities were attributed to the photogenerated holes (h⁺), superoxide (O₂ ^-) anions, and hydroxyl (^·OH) radicals. Finally, the synergistic effect of the nano-interconnected channels with octahedron geometry, mesoporous nature, and charge transfer properties along with photogenerated charge separations leads to an enhanced Co₃O₄ photocatalytic activity.