Presence of fluoride in water diminishes fast the SPR peak of silver nanocrystals showing large red shift with quick sedimentation - A fast sensing and fast removal case

Macrofungal Mediated Biosynthesis of Silver Nanoparticles and Evaluation of Its Antibacterial and Wound-Healing Efficacy

Recently, the utilization of biological agents in the green synthesis of nanoparticles has been given interest. In this study, silver nanoparticles were synthesized from an aqueous extract of macrofungus (mushroom), namely Phellinus adamantinus, in a dark room using 20 µL of silver nitrate. Biosynthesized silver nanoparticles were confirmed by analyzing them using a UV-Vis (ultraviolet-visible) spectrophotometer. The synthesized silver nanoparticles were optimized at different pH and temperatures with various dosages of AgNO3 (silver nitrate) and fungal extracts. The synthesized AgNPs (silver nanoparticles) were characterized using TEM (transmission electron microscopy) and EDX (energy-dispersive X-ray) analyses, which confirmed the presence of silver nanoparticles. The size of the nanosilver particles was found to be 50 nm with higher stability. The mycosynthesized AgNPs showed effective antibacterial activity against strains of Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (E. coli and Pseudomonas aeruginosa) bacteria. The minimum inhibitory concentration (MIC) was found to be 3.125 μg/mL by MIC assay. The MTT assay (3-[4,5-dimethylthiazol-2-yl] 2,5-diphenyl-2H-tetrazolium bromide) was performed to study cytotoxicity, and reduced cell viability was recorded at 100 μg/mL. Silver-Polygalacturonic acid-Polyvinyl alcohol ((Ag-PGA)-PVA) nanofiber was prepared using the electrospinning method. The in vitro wound scratch assay was demonstrated to study the wound-healing efficacy of the prepared nanofiber. The wound-healing efficacy of the AgNP-incorporated nanofiber was found to be 20% after 24 h. This study will lay a platform to establish a unique route to the development of a novel nanobiomaterial and its application in antibacterial and wound-healing therapy.

Tannic Acid-Functionalized Silver Nanoparticles as Colorimetric Probe for the Simultaneous and Sensitive Detection of Aluminum(III) and Fluoride Ions

In this study, we employed tannic acid (TA)-functionalized silver nanoparticles (TA@AgNPs) as colorimetric probe for the simultaneous and sensitive detection of Al(III) and F- ions. The proposed sensor was based on the aggregation and anti-aggregation effects of target Al(III) and F- ions on TA@AgNPs, respectively. Because of the strong coordination bond between Al(III) ions and TA, the addition of Al(III) ions to TA@AgNPs could cause aggregation and, hence, result in a significant change in the absorption and color of the test solution. Interestingly, in the presence of F- ions, the aggregation effect of Al(III) ions on TA@AgNPs can be effectively prevented. The extent of aggregation and anti-aggregation effects was concentration-dependent and can be used for the quantitative detection of Al(III) and F- ions. The as-proposed sensor presented the sensitive detection of Al(III) and F ions with limits of detection (LOD) of 0.2 and 0.19 μM, respectively. In addition, the proposed sensor showed excellent applicability for the detection of Al(III) and F- ions in real water samples. Moreover, the sensing strategy offered a simple, rapid, and sensitive detection procedure and could be used as a potential alternative to conventional methods, which usually involve sophisticated instruments, complicated processes, and a long detection time.

Prospects of Using Gum Arabic Silver Nanoparticles in Toothpaste to Prevent Dental Caries

There is growing interest in the use of green synthesized silver nanoparticles (AgNPs) to control and prevent dental diseases. The incorporation of green synthesized AgNPs into dentifrices to reduce pathogenic oral microbes is motivated by their presumed biocompatibility and broad-spectrum antimicrobial activity. In the present study, gum arabic AgNPs (GA-AgNPs) were formulated into a toothpaste (TP) using a commercial TP at a non-active concentration, to produce GA-AgNPs_TP. The TP was selected after evaluating the antimicrobial activity of four commercial TPs 1-4 on selected oral microbes using agar disc diffusion and microdilution assays. The less active TP-1 was then used in the formulation of GA-AgNPs_TP-1; thereafter, the antimicrobial activity of GA-AgNPs_0.4g was compared to GA-AgNPs_TP-1. The cytotoxicity of GA-AgNPs_0.4g and GA-AgNPs_TP-1 was also assessed on the buccal mucosa fibroblast (BMF) cells using the MTT assay. The study demonstrated that antimicrobial activity of GA-AgNPs_0.4g was retained after being combined with a sub-lethal or inactive concentration of TP-1. The non-selective antimicrobial activity and cytotoxicity of both GA-AgNPs_0.4g and GA-AgNPs_TP-1 was demonstrated to be time and concentration dependent. These activities were instant, reducing microbial and BMF cell growth in less than one hour of exposure. However, the use of dentifrice commonly takes 2 min and rinsed off thereafter, which could prevent damage to the oral mucosa. Although, GA-AgNPs_TP-1 has a good prospect as a TP or oral healthcare product, more studies are required to further improve the biocompatibility of this formulation.

Fiber Optic Plasmonic Sensors Based on Nanodome Arrays with Nanogaps

In this study, a high-performance fiber optic surface plasmon resonance (FO-SPR) sensor using a dome array with nanogaps (DANG) is proposed for label-free real-time detection of biomolecules. A novel and simple method using polymer beads enables high sensitivity by allowing hotspots with nanometer spacing between the Au dome and the surrounding film. The nanodome structure, which comprises a polymer core and a Au shell, induces a localized surface plasmon, expands the sensing area, and extensively enhances the electromagnetic field. The refractive index sensitivity of the FO-SPR sensor with nanostructures, i.e., with nanogaps and nanodomes, was found to be 7.8 times higher than that of the FO-SPR sensor without nanostructures. The proposed sensor achieved a low detection limit of 38 fg/mL while quantifying thyroglobulin antibody-antigen interactions and exhibited excellent selectivity. In addition, it helped detect serum samples with a 103% recovery rate.

Rationally designed and hierarchically structured functionalized aluminium organic frameworks incorporated chitosan hybrid beads for defluoridation of water

In this present investigation, aluminium (Al³⁺) fabricated 2-aminobenzene-1,4-dicarboxylic acid (ABDC) namely Al@ABDC metal organic frameworks (MOFs) was developed for defluoridation studies. The unique advantages of developed MOFs possess high selectivity, high porosity and enhanced surface area but the developed powder form of Al@ABDC MOFs has several limitations in field applications like slow filtration and column blockage. To prevail over these troubles, biopolymer namely chitosan (CS) supported Al@ABDC MOFs namely Al@ABDC-CS beads were developed for effective fluoride adsorption from water. The synthesized Al@ABDC-CS beads were employed for the retention of fluoride in batch level. The defluoridation capacities (DCs) of Al@ABDC MOFs and Al@ABDC-CS beads were found to be 4880 and 4900 mgF^- kg^-1 respectively. The influencing parameters of adsorption method namely agitation time, adsorbent dosage, initial fluoride concentration, pH, co-existing anions and temperature were exploit to get utmost defluoridation capacity (DC) of Al@ABDC-CS beads. The experimental data of Al@ABDC-CS beads have been evaluated utilizing Langmuir, Fruendlich and Dubinin-Radushkevich (D-R) isotherms. The defluoridation nature of Al@ABDC-CS beads was determined by the thermodynamic parameters. The order of reaction of Al@ABDC-CS beads was studied using various kinetic models. The regeneration and field water studies of Al@ABDC-CS beads were also carried out to check their reusability and suitability at field conditions.

Effects and behaviors of Microcystis aeruginosa in defluorination by two Al-based coagulants, AlCl3 and Al13

The complexity of natural water made it difficult to remove fluoride. Based on the environmental problems found in the investigation, the fluoride removal research in the water containing algal cells was carried out. In this study, AlCl₃ and [AlO₄Al₁₂(OH)₂₄(H₂O)₁₂]⁷⁺ (Al₁₃) were used to remove fluoride. Additionally, the role of aluminum speciation in fluoride removal and the effect of Microcystis aeruginosa on the fluoride removal by different aluminum species coagulants were elucidated. The results showed that AlCl₃ mainly removed fluoride by physical interactions, surface adsorption and enmeshment. When algal cells were added to the system, the fluoride removal rate increased from 22.75 % to 72.99 % at a dosage of 40.0 mg/L. This was because algal cells greatly increased the distribution of Al(OH)₃ in the flocs. In particular, the specific surface area of the flocs containing algal cells reached 160.77 m²/g, which allowed more fluoride to be adsorbed. However, excessive Al³⁺ led to serious damage to algal cells and release of intracellular organic matter (IOM), worsening the effect of defluoridation. F^- and Al³⁺ formed AlF²⁺ and AlF₂⁺ via complexation in water. These compounds were not conducive to defluoridation. Al₁₃ removed fluorine mainly through ion exchange, substitution and hydrogen bonding. Algal cells had an inhibitory effect on defluorination, which was observed in the process of coagulation by different Al dosages. Al₁₃ achieved agglomeration of algal cells and generated small and dense flocs through charge neutralization and electrostatic patch mechanism. Once Al₁₃ combined with algal cells and algae organic matter (AOM), the reaction between Al₁₃ and fluoride would be weakened. Al₁₃ not only maintained the defluoridation performance, but also did not damage the integrity of algal cells, even at high dosages.