Enhanced Photocatalytic and Biological Observations of Green Synthesized Activated Carbon, Activated Carbon Doped Silver and Activated Carbon/Silver/Titanium Dioxide Nanocomposites

Biogenic nano-silver doped grapefruit peels biocomposite for biosorptive photocatalytic degradation of organic pollutants

In the present study a novel biogenic nano-silver doped grapefruit peels biocomposite (GFP@Ag) has been synthesized in a single-step procedure. The GFP@Ag nano-biocomposite was characterized using UV Visible spectrophotometer, Fourier Transform infrared (FTIR), scanning electron microscopy (SEM), (EDS), Thermogravimetric analysis (TGA), Proton nuclear resonance (1HNMR), and N2 adsorption desorption isotherm (BET). A combined approach of photocatalysis and biosorption is involved for the Toluidine blue O (TO), Crystal violet (CV), and brilliant green (BG) cationic dyes utilizing GFP@Ag biocomposite at pH (4-8). The investigated dye concentration was (100-200 ppm) with contact time (20-120 min) and 0.005 g of GFP@Ag at 25 °C under visible sunlight. The maximum degradation-biosorption capacities were 194.8 mg/g, 390.6 mg/g, and 306 mg/g for TO, CV, and BG, respectively. It was concluded that the TO, CV, and BG experimental data matched the pseudo-2nd -order (PSO) and Langmuir models from the kinetic and isotherm studies, respectively. The GFP@Ag was successfully applied to remove TO, CV, and BG multi systems (binary & tertiary). It was concluded that from the thermodynamics investigation, the current photocatalytic-biosorption processes are spontaneous and endothermic. The investigation was extended to estimate a straightforward and environmentally friendly method of producing silver nanoparticles that was able to overcome the drawbacks of alternative methods. Moreover, the evaluation of the applicability of GFP@Ag for the TO, CV, and BG removal in water samples was obtained. The GFP@Ag can be regenerated after the TO removal. The mechanism of the degradation-biosorption of the pollutants under study is elucidated.

Synthesis and characterization of bamboo stem porous activated carbon/chitosan/zinc oxide (BSPAC/CS/ZnO) ternary nanocomposite for enhancement of biological activities

We report the synthesis of bamboo stem porous activated carbon/chitosan/zinc oxide (BSPAC/CS/ZnO) ternary composite using co-precipitation method. Subsequently, the synthesized BSPAC/CS/ZnO ternary nanocomposite was confirmed by FT-IR, powder XRD, Raman, FE-SEM, EDAX with elemental mapping, HR-TEM, UV-vis DRS, TGA, XPS and BET surface analysis. The distinctive surface area of composite material has been 55.354 m2/g, effectively illustrated its biological activity towards various gram positive and negative bacteria's by using disc diffusion method. In addition, BSPAC/CS/ZnO showed significant cytotoxicity against MDA-MB-231 (Human breast adeno carcinoma epithelial cell line) in a dose dependent manner and the IC50 value was found that 50.28 μg/mL. These research findings indicated that, BSPAC/CS/ZnO may lead possible application in the field of biomedical.

Green synthesis of Vitis vinifera extract-appended magnesium oxide NPs for biomedical applications

Biologically active magnesium oxide (MgO) nanoparticles were synthesised using green reduction with an extract derived from the Vitis vinifera plant. The investigation focused on examining the structure and carbon abundance resulting from the thermal degradation of adsorbed biomolecules. It was accomplished using powder X-ray diffraction, Raman spectroscopy, and FT-IR analysis techniques. X-ray photoelectron spectroscopy studies conducted on MgO nanoparticles indicate the absence of any supplementary peaks, thereby indicating the purity of the material. The morphological characteristics, which have been examined using field emission scanning electron microscopy and TEM methodologies, demonstrate the presence of particles with a spherical shape, exhibiting minimal agglomeration and a uniform distribution across the surfaces of MgO. The porous structure, porosity, and pore volume of the MgO particles were evaluated using Brunauer-Emmett-Teller surface analysis. The experimental findings reveal that the surface area of the MgO nanoparticles is 23.8742 m2/g, while the total pore volume is 0.12528 cm3/g. Additionally, the average pore diameter is determined to be 1.7 nm. These observations collectively suggest the presence of microporous structures within the MgO nanoparticles. This article discusses the biological studies to assess the antibacterial, antifungal, anti-inflammatory, and anti-diabetic activities of the synthesised MgO nanoparticles.

Investigation of antimicrobial and anti-cancer activity of thermally sensitive SnO2 nanostructures with green-synthesized cauliflower morphology at ambient weather conditions

A tin oxide (SnO2) nanostructure was prepared using Matricaria recutita leaf extract to investigate its anticancer activity against SK-MEL-28 cells. The tetragonal crystal structure of tin oxide nanoparticles with an average crystal size of 27 nm was confirmed by X-ray diffraction (XRD) analysis. The tetragonal crystal structure of the tin oxide nanoparticles, with an average crystallite size of 27 nm, was confirmed by XRD an absorbance peak at 365 nm was identified by UV-visible spectroscopy analysis as belonging to the bio-mediated synthesis of SnO2 nanoparticles. The SnO2 NPs are capped and stabilized with diverse functional groups derived from bioactive molecules, including aldehydes, benzene rings, amines, alcohols, and carbonyl stretch protein molecules. Fourier transform infrared spectroscopy (FTIR) analysis validated the presence of these capping and stabilizing chemical bonds. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies revealed the cauliflower-shaped morphology of the SnO2 nanoparticles with an average particle size of 28 nm. The antimicrobial activity of both prepared and encapsulated samples confirmed their biological activities. Furthermore, both prepared and encapsulated tin oxide samples exhibited excellent anticancer activity against SK-MEL-28 human cancer cells. The present study introduces a reliable and uncomplicated approach to produce SnO2 nanoparticles and demonstrates their effectiveness in various applications, including cancer therapy, drug administration, and disinfectant.

Using visible light to activate antiviral and antimicrobial properties of TiO2 nanoparticles in paints and coatings: focus on new developments for frequent-touch surfaces in hospitals

The COVID-19 pandemic refocused scientists the world over to produce technologies that will be able to prevent the spread of such diseases in the future. One area that deservedly receives much attention is the disinfection of health facilities like hospitals, public areas like bathrooms and train stations, and cleaning areas in the food industry. Microorganisms and viruses can attach to and survive on surfaces for a long time in most cases, increasing the risk for infection. One of the most attractive disinfection methods is paints and coatings containing nanoparticles that act as photocatalysts. Of these, titanium dioxide is appealing due to its low cost and photoreactivity. However, on its own, it can only be activated under high-energy UV light due to the high band gap and fast recombination of photogenerated species. The ideal material or coating should be activated under artificial light conditions to impact indoor areas, especially considering wall paints or frequent-touch areas like door handles and elevator buttons. By introducing dopants to TiO₂ NPs, the bandgap can be lowered to a state of visible-light photocatalysis occurring. Naturally, many researchers are exploring this property now. This review article highlights the most recent advancements and research on visible-light activation of TiO₂-doped NPs in coatings and paints. The progress in fighting air pollution and personal protective equipment is also briefly discussed.

Graphical Abstract

Indoor visible-light photocatalytic activation of reactive oxygen species (ROS) over TiO₂ nanoparticles in paint to kill bacteria and coat frequently touched surfaces in the medical and food industries.

Synthesis, characterization, antimicrobial and photocatalytic properties of nano-silver-doped flax fibers

In the present study, the nano-silver-doped flax fibers (NAgDFF) are prepared in two steps. In the first step, oxidation of the flax fibers is performed by potassium periodate to form dialdehyde cellulose (DAC) and the second step is the reduction of silver ions by DAC. A series of characterization techniques of the photocatalyst NAgDFF was carried out using scanning electron microscopy, Fourier transform infrared spectroscopy, N2 adsorption isotherm, thermogravimetric analysis and energy-dispersive X-ray spectroscopy. The dye degradation potential of NAgDFF for methylene blue (MB), crystal violet (CV) and brilliant green (BG) (individually or mixture) was investigated using batch and column tests. The degradation efficiency was studied under optimized conditions such as pH (5.0), dye initial concentrations (100 ppm for MB and BG, and 150 ppm for CV), contact time (3.0 h), photocatalyst NAgDFF dose (0.08 g) and temperature (25° C). The maximum degradation efficiency of NAgDFF for MB, CV and BG is 64.75, 94.98 and 63.87 (mg/g), respectively. The kinetic studies show that the experimental data match well with the pseudo-second-order kinetic model. Furthermore, equilibrium isotherm data were analyzed according to Langmuir, Freundlich and Dubinin–Radushkevich equations. The thermodynamic parameters for the adsorption processes of cationic dyes on the NAgDFF fibers were also calculated; the negative value of ΔG° indicated the spontaneous nature of sorption. NAgDFF fibers were successfully applied for photodegradation of the investigated cationic dyes from different samples. The study was extended to investigate the biological activity of newly synthesized NAgDFF against various microorganisms.