Efficient photocatalytic bactericidal performance of green-synthesised TiO2/reduced graphene oxide using banana peel extracts.

In this study, the fabrication of titanium dioxide/reduced graphene oxide (TiO2/rGO) utilising banana peel extracts (Musa paradisiaca L.) as a reducing agent for the photoinactivation of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was explored. The GO synthesis was conducted using a modified Tour method, whereas the production of rGO involved banana peel extracts through a reflux method. The integration of TiO2 into rGO was achieved via a hydrothermal process. The successful synthesis of TiO2/rGO was verified through various analytical techniques, including X-ray diffraction (XRD), gas sorption analysis (GSA), Fourier-transform infrared (FT-IR) spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), scanning electron microscope-energy dispersive X-ray (SEM-EDX) and transmission electron microscopy (TEM) analyses. The results indicated that the hydrothermal-assisted green synthesis effectively produced TiO2/rGO with a particle size of 60.5 nm. Compared with pure TiO2, TiO2/rGO demonstrated a reduced crystallite size (88.505 nm) and an enhanced surface area (22.664 m2/g). Moreover, TiO2/rGO featured a low direct bandgap energy (3.052 eV), leading to elevated electrical conductivity and superior photoconductivity. To evaluate the biological efficacy of TiO2/rGO, photoinactivation experiments targeting E. coli and S. aureus were conducted using the disc method. Sunlight irradiation emerged as the most effective catalyst, achieving optimal inactivation results within 6 and 4 h.

Hydrothermally synthesized titanium/hydroxyapatite as photoactive and antibacterial biomaterial.

The present work investigated hydrothermal synthesis of titanium/hydroxyapatite (Ti/HA) nanocomposite at varied Ti content. The synthesis was performed by coprecipitation method using CaO, ammonium dihydrogen phosphate and titanium oxide chloride precursor with the additional cetyl trimethyl ammonium chloride as templating agent, followed by hydrothermal treatment at 150 °C. The derived materials were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy analyses. The photocatalytic properties of materials were tested on methyl violet (MV) photocatalytic oxidation, meanwhile the antibacterial testing was performed against Escherichia coli, Staphylococcus aureus, Klebsiella pneumonia, and Streptococcus pyogenes. In addition, cytotoxicity evaluation of the materials as potential biomaterial was also conducted. The results showed that physicochemical character of Ti/HA exhibits exhibit the excellent properties to be photocatalyst along with antibacterial activity. From the detail study of effect of varied titanium content ranging from 5 to 10 %wt., the increasing crystallite size of anatase phase of about 25.81 nm and 38.22 nm for Ti content of 5 and 10 % wt., respectively. In other side, the band gap energy value increases as the increasing Ti content, i.e. the values are 3.08; 3.18; and 3.20 eV for Ti content of 5, 10, 20 % wt., respectively. The band gap energy is correlated with the photocatalytic activity which the highest MV degradation was 96.46% over Ti/HA with 20% wt. of Ti (Ti20/HA). The nanocomposites also express the antibacterial activity with comparable minimum inhibitory concentration (MIC) with other similar Ti/HA nanocomposites. The MIC values of Ti20/HA against E. coli, S. aureus, K. pneumonia, and S. pyogenes are 25; 25; 50 and 50 µg/mL, respectively. In addition, the cytotoxicity test revealed the potency to be a biomimetic material as shown by severe toxicity.

Green Synthesis of Silver Nanoparticles Using Datura metel Flower Extract Assisted by Ultrasound Method and Its Antibacterial Activity.

BACKGROUND: Green synthesis method of nanoparticles has been developed for several years. Besides providing environmental-friendly process, green synthesis of nanoparticles using plant extract provides synergistic effect of the secondary metabolite in such antibiotic activity. The study with an intensification process in nanoparticles formation is also gaining great attention. This research deals with the green synthesis of silver nanoparticles using Datura metel flower extract for the antibacterial agent. The use of ultrasound-assisted method for the synthesis was investigated. METHODS: Synthesis of silver nanoparticles (AgNPs) using Datura metel flower extract under ultrasound- assisted method has been conducted. Evaluation of the successful synthesis was done using UV-visible spectrophotometry, particle size analyzer, x-ray diffraction, and transmission electron microscopy. The prepared AgNPs were tested as an antibacterial against S. aureus, K. pneumoniae, S. pyogenes, and E. coli. RESULTS: The ultrasound-assisted synthesis of AgNPs produces particles ranging from 25-70 nm in size; meanwhile, the reflux method demonstrated the size of 50-170 nm. These particles size represents the effect on the antibacterial activity as the ultrasound-assisted synthesized Ag NPs have higher inhibition zone towards all tested bacteria. Subsequently, these data presented the applicability of Ag NPs synthesis using an ultrasound method as a potential candidate for biomedical applications. CONCLUSION: The profile of UV-Visible spectra and particle size analyses demonstrated the applicability of the ultrasound technique to produce a smaller size of the nanoparticles with higher antibacterial activity.

Green Synthesis of Antibacterial Nanocomposite of Silver Nanoparticle-Doped Hydroxyapatite Utilizing Curcuma longa Leaf Extract and Land Snail (Achatina fulica) Shell Waste.

Preparation of green synthesized silver nanoparticle (AgNPs)-doped hydroxyapatite (Ag/HA) utilizing Curcuma longa leaf extract and land snail (Achatina fulica) shell waste was performed. Physicochemical characteristics and antibacterial activity of Ag/HA composite as a function of Ag content was studied. Instrumental analysis such as XRD, SEM-EDX, TEM, and XPS were employed to characterize the nanocomposites. The physicochemical study revealed the maintained porous structure of HA after Ag immobilization, and from TEM analyses, it was found that the distributed spherical particles are associated with the dispersed Ag and have a particle diameter of around 5-25 nm. Antibacterial activity of the nanocomposite was evaluated against Escherichia coli, Staphylococcus aureus, Kliebsiella, pneumonia, and Streptococcus pyogenes. The results showed that the varied Ag content (1.0; 1.6; and 2.4% wt) influenced the nanoparticle distribution in the nanocomposite and enhanced the antibacterial feature.

Flower-like SnO2 Nanoparticle Biofabrication Using Pometia pinnata Leaf Extract and Study on Its Photocatalytic and Antibacterial Activities.

The present study reported biofabrication of flower-like SnO2 nanoparticles using Pometia pinnata leaf extract. The study focused on the physicochemical characteristics of the prepared SnO2 nanoparticles and its activity as photocatalyst and antibacterial agent. The characterization was performed by XRD, SEM, TEM, UV-DRS and XPS analyses. Photocatalytic activity of the nanoparticles was examined on bromophenol blue photooxidation; meanwhile, the antibacterial activity was evaluated against Klebsiella pneumoniae, Escherichia coli Staphylococcus aureus and Streptococcus pyogenes. XRD and XPS analyses confirmed the single tetragonal SnO2 phase. The result from SEM analysis indicates the flower like morphology of SnO2 nanoparticles, and by TEM analysis, the nanoparticles were seen to be in uniform spherical shapes with a diameter ranging from 8 to 20 nm. SnO2 nanoparticles showed significant photocatalytic activity in photooxidation of bromophenol blue as the degradation efficiency reached 99.93%, and the photocatalyst exhibited the reusability as the degradation efficiency values were insignificantly changed until the fifth cycle. Antibacterial assay indicated that the synthesized SnO2 nanoparticles exhibit an inhibition of tested bacteria and showed a potential to be applied for further environmental and medical applications.