Eco-Friendly Synthesis and Comparative In Vitro Biological Evaluation of Silver Nanoparticles Using Tagetes erecta Flower Extracts

The present study reports an eco-friendly synthesis method of silver nanoparticles (AgNPs) using two different extracts (aqueous and ethanolic) of Tagetes erecta flowers. When exposed to different biocompounds found in the plant, silver ions are reduced, thus, resulting in the green synthesis of nanoparticles. After performing the optimization of synthesis, the obtained AgNPs were characterized using various techniques. The UV–Vis spectrum of the synthesized nanoparticles showed maximum peaks at 410 and 420 nm. TEM analysis revealed that the particles were spherical with a size ranging from 10 to 15 nm, and EDX analysis confirmed the presence of silver metal. The average diameter value obtained through DLS analysis for the two types of AgNPs (obtained using aqueous and ethanolic extracts) was 104 and 123 nm. The Zeta potentials of the samples were −27.74 mV and −26.46 mV, respectively, which indicates the stability of the colloidal solution. The antioxidant and antimicrobial activities assays showed that nanoparticles obtained using the aqueous extract presented enhanced antioxidant activity compared to the corresponding extract, with both types of AgNPs exhibiting improved antifungal properties compared to the initial extracts.

Sustainable Green Nanotechnologies for Innovative Purifications of Water: Synthesis of the Nanoparticles from Renewable Sources

Polluting the natural water resources is a serious global issue, which is confirmed by the fact that today at least 2 billion people consume water from contaminated sources. The conventional wastewater treatment methods cannot effectively remove the persistent pollutants (e.g., drugs, organic dyes, pesticides) from the aqueous environment. Heterogeneous photocatalysis is a promising and sustainable alternative for water remediation. It is based on the interaction between light irradiation and the semiconductors (e.g., TiO2, ZnO) as photocatalysts, but these compounds, unfortunately, have some disadvantages. Hence, great attention has been paid to the nanotechnology as a possible way of improvement. Nanomaterials have extraordinary properties; however, their conventional synthesis is often difficult and requires a significant amount of dangerous chemicals. This concise topical review gives recent updates and trends in development of sustainable and green pathways in the synthesis of nanomaterials, as well as in their application for water remediation. In our review we put emphasis on the eco-friendly, mostly plant extract-based materials. The importance of this topic, including this study as well, is proved by the growing number of publications since 2018. Due to the current serious environmental issues (e.g., global warming, shortage of pure and quality water), it is necessary for the traditional TiO2 and ZnO semiconductors to be replaced with the harmless, non-toxic, and more powerful nanocomposites as photocatalysts. Not only because of their higher efficiency as compared to the bulk semiconductors, but also because of the presence of biomolecules that can add up to the pollutant removal efficiency, which has been already confirmed in many researches. However, despite the fact that the application of heterogeneous photocatalysis together with green nanotechnology is absolutely the future in water purification, there are some challenges which have to be overcome. The exact effects of the biomolecules obtained from plants in the synthesis of nanoparticles, as well as in the photocatalytic processes, are not exactly known and require further investigation. Furthermore, heterogeneous photocatalysis is a well-known and commonly examined process; however, its practical use outside the laboratory is expensive and difficult. Thus, it has to be simplified and improved in order to be available for everyone. The aim of our review is to suggest and prove that using these bio-inspired compounds it is possible to reduce human footprint in the nature.

Biogenic Ferrihydrite Nanoparticles Produced by Klebsiella oxytoca: Characterization, Physicochemical Properties and Bovine Serum Albumin Interactions

The synthesis of nanoparticles inside microorganisms is an economical alternative to chemical and physical methods of nanoparticle synthesis. In this study, ferrihydrite nanoparticles synthesized by Klebsiella oxytoca bacterium in special conditions were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS), small-angle X-ray (SAXS), UV-Vis spectroscopy, fluorescence, fluorescence resonance energy transfer (FRET), and molecular docking. The morphology and the structure of the particles were characterized by means of SEM and SAXS. The elemental content was determined by means of the EDS method. The absorption properties of the ferrihydrite nanoparticles were investigated by UV-Vis spectroscopy. The binding mechanism of the biogenic ferrihydrite nanoparticles to Bovine Serum Albumin (BSA) protein, studied by fluorescence, showed a static and weak process, combined with FRET. Protein denaturation by temperature and urea in the presence of the ferrihydrite nanoparticles demonstrated their influence on the unfolding process. The AutoDock Vina and UCSF Chimera programs were used to predict the optimal binding site of the ferrihydrite to BSA and to find the location of the hydrophobic cavities in the sub-domain IIA of the BSA structure.

Investigating the Production of Antimicrobial Nanoparticles by Chlorella vulgaris and the Link to Its Loss of Viability

Chlorella vulgaris from Al-Ahsa, KSA was proved to be an active silver and gold nanoparticle producer. Nanogold and nanosilver particles were characterized using UV-visible spectroscopy, Fourier-transform infrared spectroscopy, and scanning electronmicroscopy. Both nanoparticles were used in the antimicrobial bioassay. The two nanoparticles showed antibacterial activities, with the silver nanoparticles being the most effective. To investigate the argumentative nature of their biosynthesis (i.e., whether it is a biotic or abiotic process), we isolated total ribonucleic acid RNA as an indicator of vitality. RNA was completely absent in samples taken after one week of incubation with silver nitrate and even after one or two days. However, successful extraction was only achievable in samples taken after incubation for one and four hours with silver nitrate. Most importantly, the gel image showed recognizable shearing of the nucleic acid after 4 h as compared to the control. An assumption can be drawn that the synthesis of nanoparticles may start biotically by the action of enzyme(s) and abiotically by action of reducing entities. Nonetheless, with prolonged incubation, excessive nanoparticle accumulation can be deadly. Hence, their synthesis continues abiotically. From the RNA banding profile, we suggest that nanosilver production starts both biotically and abiotically in the first few hours of incubation and then continues abiotically. Nanosilver particles proved to have more of an antimicrobial impact than nanogold and hence are recommended for different applications as antibacterial agents.

Bacteria as an Efficient Bacteriosystem for the Synthesis of Nanoparticles: A Bibliometric Analysis

The growth trend of publications in the field of nanoparticles biosynthesis by bacteria was analyzed using bibliometric techniques to the identification of the areas with significant development and the orientations that have guided the research on bacteria. This study extracted data from the Clarivate Analytics Web of Science (WoS) and Scopus between 2000 and 2020 to compare results. The number of articles published annually, participating countries, resource growth rate, most used keywords and research collaborations were obtained from bibliometric analysis. The results showed that nanoparticle documents in materials science, biochemistry, genetics and molecular biology have improved citation rates as the authors researched in multidisciplinary areas. Although these keywords have the most sites, they are not emerging keywords, and their most common use was in the years 2014–2018. The results showed the upward trend of articles published from 2000 to 2020, most of which were related to the last 10 years. The 5 countries that had the most articles published in this field were China, USA, India, Germany and Iran. The top sources that had the most published documents in this field had a similar scope to our research. The results of each section had a significant relationship with other sections of this study. VOS viewer program was used for quantitative analysis. It seems that bibliometric methods will complement meta-analysis and qualitative structured literature reviews as a method for reviewing and evaluating scientific literature. The advantage of the bibliographic analysis was the awareness of trends in a study area.

Juice nanotechnology: A mini review

In the past two decades, nano-science is widely used in different applications and the increased interest in the utilization of nanoparticles in food processing is clear. Such applications include processing, packaging, development of functional food, safety, foodborne pathogens detection, and shelf-life extension. In this article, the essential facts and the latest uses of nano-science in fruit and vegetable juices were described. The green synthesis of nanoparticles with antioxidant, antibacterial and antifungal characteristics is of great interest in food preservation. These nanoparticles such as metals, oxidized metals and its bioactivity in juice were reviewed. The current procedures to prepare nanojuice including nanofiltration and the most recent nanomilling were presented. Beside the preparation, special emphasis has also been given to the chemical as well as the biological (microbial and enzymatic) quality of the produced nanojuice. The role of nanotechnology in the development of the smart and the active food packaging systems for the improvement of food shelf- life and quality was also discussed. Since the physical and chemical characteristics of nanoparticles are completely different from those of macro-size. Therefore, special and urgent attention by responsible authorities should be given and effective policies should be applied for food products to ensure product quality, customer health and safety as well as the environmental protection.

Physical-chemical and Biological Properties of Novel Resin-based Composites for Dental Applications

Insufficient mechanical properties of hydroxyapatite -based composites prompted the search for new and effective solutions for dental applications. To improve the mechanical properties without losing the remineralization potential, the use of hybrid fillers was proposed. The first of them was based on the formation of hydroxyapatite (HA) layer on the surface of SYLOID®244 silica. The second of the investigated fillers was created by simultaneous synthesis of nanoparticles from precursors of HA and silica. The obtained fillers were extensively characterized by spectral methods including X-ray Diffractometry (XRD), Fourier-Transform Infrared Spectroscopy (FT-IR), and X-ray fluorescence (XRF), as well as by Scanning Electron Microscopy (SEM)/Energy Dispersive Spectroscopy (EDS). Tests using probiotic microorganisms were an important part of the analysis, indicating that there was no potential interaction of the materials with microflora. The tests of degree of conversion, depth of cure, opacity, sorption, solubility, flexural and compressive strength, and the remineralizing potential also showed that the composites with nano-sized silica/HA showed better mechanical properties than the composites with HA alone or commercial silica and at the same time the remineralization remained at the desired level. Thus, the proposed composite has a high application potential in the creation of implants and dental materials.

Innovative and Biocompatible Approaches for Nanomaterial Production and Application

The world is going green; hence, environmentally friendly practices that would conserve natural resources for the future generation are encouraged. As a consequence, the world is less concerned about the numerous applications of nanotechnology, especially in the health sector; rather, it is more concerned about the sustainability of functionalized nanomaterials. Thus, the future of nanotechnology depends on its ability to ‘go green'. Green nanotechnology attempts to synthesize improved, nontoxic, and biocompatible nanomaterials with sustainable benefits using eco-friendly materials. Although green nanotechnology is considered a sustainable, viable, and biocompatible approach to the production of eco-friendly nanomaterials, there are shortcomings especially in microbial handling and process optimization. In this chapter, the authors aim to appraise not only the use of biocompatible approaches for the synthesis of nanoparticles and/or nanomaterials but also their shortcomings.

Synthesis of Insulin Loaded Nanoparticles and Their Antidiabetic Studies

The goal of this present work turned into synthesis of polymeric nanoparticles from natural polymeric material. Natural polymeric nanoparticles have some unique physicochemical properties like stability, biocompatibility, biodegradability, and manage the drug release, so it’s used for drug transport. On this look natural polymeric material Casein and Chitosan are used for the synthesis of nanoparticles. Insulin drug was introduced to these polymeric nanoparticles, which are used for the drug delivery. These drug loaded polymeric nanoparticles are synthesised by nano precipitation technique. The particles size of drug loaded polymeric nanoparticles based totally the rate of stirring and time of nanoparticles synthesised. Insulin was used as a drug and Glutaraldehyde was used as a linking agent. This insulin drug becomes adsorbed on the surface of the nanoparticles. Those drug loaded nanoparticles are characterized by FT-IR spectrum and physical status is analysis by means of XRD pattern. The morphology of the drug loaded nanoparticles is studied by using Scanning Electron Microscopy (SEM). From those characterisation studies insulin drug was efficaciously loaded with the nanoparticles. It has high inhibitory property towards kind II diabetics.