Chacrawarthige A. N. Fernando

Silver nanoparticles (AgNPs) are widely recognized as a prominent antimicrobial agent and have found applications in the field of medicine. This study focuses on the synthesis of AgNPs utilizing the natural reducing agent of Ceylon olive (Elaeocarpus serratus), presenting an economically viable and ecologically friendly approach. For the first time, this research demonstrated the synthesis of AgNPs using phytochemicals extracted from Ceylon olive, serving as both natural reducing and stabilizing agents. The synthesized AgNPs were characterized with UV–visible spectroscopy, a particle size analyzer (PSA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) coupled with an energy dispersive X-ray spectrometer (EDX). The UV–visible spectra primarily indicated the formation of the AgNPs by the surface plasmon resonance band around 434 nm. SEM analysis confirmed the presence of silver nanoparticles within a size range of 50–110 nm, with an average size of approximately 70 nm. FTIR determined that proteins, phenols, and flavonoids may have acted as reducing and capping agents. Experimental parameters were optimized to improve the yield and size of the AgNPs and eventually evaluate their antibacterial properties. The well diffusion method exhibits a significantly larger zone of inhibition for Gram-negative bacterial strains (18.4 ± 0.55 mm for Pseudomonas aeruginosa and 14.4 ± 0.55 mm for Escherichia coli) compared to Gram-positive bacterial strains (11.6 ± 0.55 mm for Staphylococcus aureus and 10.4 ± 0.55 mm for Staphylococcus epidermidis) for 50 µg/mL AgNPs. These findings demonstrate that AgNPs synthesized with Ceylon olive have the potential to develop into novel materials for bacterial-mediated diseases.

Cellulose is one of the most widely used natural polymers developed in eco-friendly methods, which has been used in various industrial processes and products since ancient times. The sources of cellulose materials are plant and wood fibers. Cellulosic materials are converted into cellulose nanocrystals (CNCs) using mechanical or chemical methods. In this study, the CNCs were obtained from cotton balls by acid hydrolysis method using sulfuric acid. The sulfuric acid hydrolysis method was performed with 64% (w/w) sulfuric acid and combined using a liquor ratio of 1:20 with cotton balls while being subjected to vigorous stirring at 50°C for 60 minutes. The cellulose nanocrystals were characterized by Transmission Electron Microscopy (TEM), Fourier Transform Infrared (FTIR) spectroscopy analysis and X-ray Diffraction (XRD) techniques. The extracted cellulose nanocrystals had needle-shaped particles with a 6.35 nm average diameter and a length of 108.8 nm on average. The functional groups of the extracted cellulose nanocrystals were shown to have been evaluated through analysis of the FTIR spectra. Therefore, it was confirmed that the cellulose nanocrystals were successfully extracted from cotton balls using sulfuric acid hydrolysis. The distinctive crystalline cellulose phase of artificial cellulose nanocrystals was recognized using the XRD spectrum.

Two series of zirconium-incorporated-periodic-mesoporous-organosilica (Zr–PMO) materials were successfully prepared, via a co-condensation strategy, in the presence of Pluronic P123 triblock copolymer. The first series of Zr–PMO was prepared using tris[3-(trimethoxysilyl)propyl]isocyanurate (ICS), tetraethylorthosilicate (TEOS), and zirconyl chloride octahydrate(ZrCO), denoted as Zr-I-PMO, where I refers to ICS. The second series was synthesized using bis(triethoxysilyl)benzene (BTEE), TEOS, and ZrCO as precursors, named as Zr-B-PMO, where B refers to BTEE. Zr–PMO samples exhibit type (IV) adsorption isotherms, with a distinct H2-hysteresis loop and well-developed structural parameters, such as pore volume, pore width, high surface area, and narrow pore-size distribution. Structural properties were studied by varying the Zr:Si ratio, adding TEOS at different time intervals, and changing the amount of block copolymer-Pluronic P123 used as well as the calcination temperature. Surface characteristics were tailored by precisely controlling the Zr:Si ratio, upon varying the amount of TEOS present in the mesostructures. The addition of TEOS at different synthesis stages, notably, enhanced the pore size and surface area of the resulting Zr-I-PMO samples more than the Zr-B-PMO samples. Changing the amount of block copolymer, also, played a significant role in altering the textural and morphological properties of the Zr-I-PMO and Zr-B-PMO samples. Optimizing the amount of Pluronic P123 added is crucial for tailoring the surface properties of Zr–PMOs. The prepared Zr–PMO samples were examined for use in CO₂ sorption, at ambient temperature and pressure (25 °C, 1.2 bar pressure). Zr–PMO samples displayed a maximum CO₂ uptake of 2.08 mmol/g, at 25 °C and 1.2 bar pressure. However, analogous zirconium samples, without any bridging groups, exhibited a significantly lower CO₂ uptake, of 0.72 mmol/g, under the same conditions. The presence of isocyanurate- and benzene-bridging groups in Zr-I-PMO and Zr-B-PMO samples enhances the CO₂ sorption. Interestingly, results illustrate that Zr–PMO materials show potential in capturing CO₂, at ambient conditions.