Biogenic synthesis of silver nanoparticles using S1 genotype of Morus alba leaf extract: characterization, antimicrobial and antioxidant potential assessment

From nature to nanomedicine: bioengineered metallic nanoparticles bridge the gap for medical applications

The escalating global challenge of antimicrobial resistance demands innovative approaches. This review delves into the current status and future prospects of bioengineered metallic nanoparticles derived from natural sources as potent antimicrobial agents. The unique attributes of metallic nanoparticles and the abundance of natural resources have sparked a burgeoning field of research in combating microbial infections. A systematic review of the literature was conducted, encompassing a wide range of studies investigating the synthesis, characterization, and antimicrobial mechanisms of bioengineered metallic nanoparticles. Databases such as PubMed, Scopus, Web of Science, ScienceDirect, Springer, Taylor & Francis online and OpenAthen were extensively searched to compile a comprehensive overview of the topic. The synthesis methods, including green and sustainable approaches, were examined, as were the diverse biological sources used in nanoparticle fabrication. The amalgamation of metallic nanoparticles and natural products has yielded promising antimicrobial agents. Their multifaceted mechanisms, including membrane disruption, oxidative stress induction, and enzyme inhibition, render them effective against various pathogens, including drug-resistant strains. Moreover, the potential for targeted drug delivery systems using these nanoparticles has opened new avenues for personalized medicine. Bioengineered metallic nanoparticles derived from natural sources represent a dynamic frontier in the battle against microbial infections. The current status of research underscores their remarkable antimicrobial efficacy and multifaceted mechanisms of action. Future prospects are bright, with opportunities for scalability and cost-effectiveness through sustainable synthesis methods. However, addressing toxicity, regulatory hurdles, and environmental considerations remains crucial. In conclusion, this review highlights the evolving landscape of bioengineered metallic nanoparticles, offering valuable insights into their current status and their potential to revolutionize antimicrobial therapy in the future.

Alginate-Based Carriers Loaded with Mulberry (Morus alba L.) Leaf Extract: A Promising Strategy for Prolonging 1-Deoxynojirimicyn (DNJ) Systemic Activity for the Nutraceutical Management of Hyperglycemic Conditions

The iminosugar 1-deoxynojirimicyn (DNJ) contained in mulberry leaves has displayed systemic beneficial effects against disorders of carbohydrate metabolism. Nevertheless, its effect is impaired by the short half-life. Alginate-based carriers were developed to encapsulate a DNJ-rich mulberry extract: Ca-alginate beads, obtained by external gelation, and spray-dried alginate microparticles (SDMs). Mean size and distribution, morphology, drug loading, encapsulation efficiency, experimental yield, and release characteristics were determined for the two formulations. Ca-alginate beads and SDMs exhibited an encapsulation efficiency of about 54% and 98%, respectively, and a DNJ loading in the range of 0.43-0.63 μg/mg. The in vitro release study demonstrated the carriers' capability in controlling the DNJ release in acid and basic conditions (<50% in 5 h), due to electrostatic interactions, which were demonstrated by 1H-NMR relaxometry studies. Thus, alginate-based particles proved to be promising strategies for producing food supplements containing mulberry leaf extracts for the management of hyperglycemic state.

Monocyte (THP-1) Response to Silver Nanoparticles Synthesized with Rumex hymenosepalus Root Extract

The study, synthesis, and application of nanomaterials in medicine have grown exponentially in recent years. An example of this is the understanding of how nanomaterials activate or regulate the immune system, particularly macrophages. In this work, nanoparticles were synthesized using Rumex hymenosepalus as a reducing agent (AgRhNPs). According to thermogravimetric analysis, the metal content of nanoparticles is 55.5% by weight. The size of the particles ranges from 5-26 nm, with an average of 11 nm, and they possess an fcc crystalline structure. The presence of extract molecules on the nanomaterial was confirmed by UV-Vis and FTIR. It was found by UPLC-qTOF that the most abundant compounds in Rh extract are flavonols, flavones, isoflavones, chalcones, and anthocyanidins. The viability and apoptosis of the THP-1 cell line were evaluated for AgRhNPs, commercial nanoparticles (AgCNPs), and Rh extract. The results indicate a minimal cytotoxic and apoptotic effect at a concentration of 12.5 μg/mL for both nanoparticles and 25 μg/mL for Rh extract. The interaction of the THP-1 cell line and treatments was used to evaluate the polarization of monocyte subsets in conjunction with an evaluation of CCR2, Tie-2, and Arg-1 expression. The AgRhNPs nanoparticles and Rh extract neither exhibited cytotoxicity in the THP-1 monocyte cell line. Additionally, the treatments mentioned above exhibited anti-inflammatory effects by maintaining the classical monocyte phenotype CD14++CD16, reducing pro-inflammatory interleukin IL-6 production, and increasing IL-4 production.

Optimization of the biosynthesis of silver nanoparticles using bacterial extracts and their antimicrobial potential

In the present study, silver nanoparticles (AgNPs) were biosynthesized using the supernatant and the intracellular extract of Cupriavidus necator, Bacillus megaterium, and Bacillus subtilis. The characterization of the AgNPs was carried out using UV-Vis spectroscopy, FTIR, DLS and TEM. Resazurin microtiter-plate assay was used to determine the antimicrobial action of AgNPs against Escherichia coli. UV-Visible spectra showed peaks between 414 and 460 nm. TEM analysis revealed that the synthesized AgNPs showed mostly spherical shapes. DLS results determined sizes from 20.8 to 118.4 nm. The highest antimicrobial activity was obtained with the AgNPs synthesized with supernatant rather than those using the intracellular extract. Therefore, it was determined that the bacterial species, temperature, pH, and type of extract (supernatant or intracellular) influence the biosynthesis. This synthesis thus offers a simple, environmentally friendly, and low-cost method for the production of AgNPs, which can be used as antibacterial agents.

Application of Nanomaterials in the Production of Biomolecules in Microalgae: A Review

Nanomaterials (NMs) are becoming more commonly used in microalgal biotechnology to empower the production of algal biomass and valuable metabolites, such as lipids, proteins, and exopolysaccharides. It provides an effective and promising supplement to the existing algal biotechnology. In this review, the potential for NMs to enhance microalgal growth by improving photosynthetic utilization efficiency and removing reactive oxygen species is first summarized. Then, their positive roles in accumulation, bioactivity modification, and extraction of valuable microalgal metabolites are presented. After the application of NMs in microalgae cultivation, the extracted metabolites, particularly exopolysaccharides, contain trace amounts of NM residues, and thus, the impact of these residues on the functional properties of the metabolites is also evaluated. Finally, the methods for removing NM residues from the extracted metabolites are summarized. This review provides insights into the application of nanotechnology for sustainable production of valuable metabolites in microalgae and will contribute useful information for ongoing and future practice.

Green synthesized cobalt nanoparticles from Trianthema portulacastrum L. as a novel antimicrobials and antioxidants

Trianthema portulacastrum is a dietary and medicinal plant that has gained substantial importance due to its pharmacological properties. This plant was used for its various healing properties since the ancient period in ayurvedic system of medicine. The green synthesis technique is an eco-friendly as well as cost effective technique which can produce more biocompatible nanoparticles when compared with those fabricated by physio-chemical methods. Therefore, nanoparticles produced by green synthesis are credible alternatives to those which are produced by conventional synthesis techniques. This research mainly aims to produce nanoparticles with the methanolic leaf extract of T. portulacastrum. The optimized nanoparticles were further analyzed for anti-fungal, anti-bacterial and antioxidant properties. Disk diffusion assay was used for the determination of the antimicrobial property and on the other hand, DPPH radical scavenging assay as well as hydrogen peroxide scavenging activity proved the antioxidant property of the formulation. The study revealed that Escherichia coli (gram negative strain) shows greater zone of inhibition when compared with Bacillus subtilis (gram positive bacteria). The nanoparticles have also been reported to show significant anti-fungal activity against the strains of Aspergillus niger and Fusarium oxysporum which proves its desirability for its further use against both bacterial as well as fungal infections. The novel formulation can be explored dually as antimicrobial and antioxidant agent.

Phytochemicals: potential alternative strategy to fight Salmonella enterica serovar Typhimurium

The rise of multidrug resistant (MDR) microorganisms is a great hazard worldwide and has made it difficult to treat many infectious diseases adequately. One of the most prevalent causes of outbreaks of foodborne illness worldwide is Salmonella. The ability of this and other harmful bacteria to withstand antibiotics has recently proven crucial to their effective control. Since the beginning of time, herbal medicines and phytochemicals have been employed for their potent antibacterial action and there is a growing trend toward the production of plant based natural products for the prevention and treatment of pathogenic infections. Numerous phytochemicals have been proven effective against the molecular determinants responsible for attaining drug resistance in pathogens like efflux pumps, membrane proteins, bacterial cell communications and biofilms. The medicinal plants having antibacterial activity and antibiotics combination with phytochemicals have shown synergetic activity against Salmonella enterica serovar Typhimurium. The inhibitory effects of tannins on rumen proteolytic bacteria can be exploited in ruminant nutrition. Improved control of the rumen ecology and practical use of this feed additive technology in livestock production will be made possible by a better knowledge of the modulatory effects of phytochemicals on the rumen microbial populations in combination with fermentation. This review focuses on the development of antibacterial resistance in Salmonella, the mechanism of action of phytochemicals and the use of phytochemicals against S. enterica serovar Typhimurium. The advances and potential future applications of phytochemicals in the fight against resistant are also discussed.

Nanoantioxidant Materials: Nanoengineering Inspired by Nature

Oxidants are very active compounds that can cause damage to biological systems under specific environmental conditions. One effective way to counterbalance these adverse effects is the use of anti-oxidants. At low concentrations, an antioxidant is defined as a compound that can delay, control, or prevent an oxidative process. Antioxidants exist in plants, soil, and minerals; therefore, nature is a rich source of natural antioxidants, such as tocopherols and polyphenols. In nature, antioxidants perform in tandem with their bio-environment, which may tune their activity and protect them from degradation. In vitro use of antioxidants, i.e., out of their biomatrix, may encounter several drawbacks, such as auto-oxidation and polymerization. Artificial nanoantioxidants can be developed via surface modification of a nanoparticle with an antioxidant that can be either natural or synthetic, directly mimicking a natural antioxidant system. In this direction, state-of-the-art nanotechnology has been extensively incorporated to overcome inherent drawbacks encountered in vitro use of antioxidants, i.e., out of their biomatrix, and facilitate the production and use of antioxidants on a larger scale. Biomimetic nanoengineering has been adopted to optimize bio-medical antioxidant systems to improve stability, control release, enhance targeted administration, and overcome toxicity and biocompatibility issues. Focusing on biotechnological sciences, this review highlights the importance of nanoengineering in developing effective antioxidant structures and comparing the effectiveness of different nanoengineering methods. Additionally, this study gathers and clarifies the different antioxidant mechanisms reported in the literature and provides a clear picture of the existing evaluation methods, which can provide vital insights into bio-medical applications.

Intrinsic Light-Activated Oxidase Mimicking Activity of Conductive Polyaniline Nanofibers: A Class of Metal-Free Nanozyme

In recent decades, studies have focused on inorganic nanozymes to overcome the intrinsic drawbacks of bioenzymes due to the demands of improving the reaction conditions and lack of robustness to harsh environmental factors. Many biochemical reactions catalyzed by enzymes require light activation. Light-activated nanozymes have distinct advantages, including being regulated by light stimuli, activating the molecular oxygen to produce reactive oxygen species (ROS) without interfering supplementary oxidants, and often showing a synergistic effect to catalyze some challenging reactions. Only a few studies have been done on this connection. Therefore, it is still a big challenge to develop a nanozyme regulated by light activation. Herein, we uncovered the light-activated oxidase mimicking activity of a conducting polymer polyaniline nanofibers (PANI-NFs). PANI-NFs exhibit intrinsic light-activated brilliant oxidase-like activity, can catalyze the colorless tetramethyl benzidine (TMB) to produce a blue product TMBox, and have a distinct K_m = 0.087 mM and a high V_max = 2.32 μM min^-1 value, measured by using Hanes-Woolf kinetics. We also report the light-activated oxidase activity of some other renowned carbocatalysts graphene oxide and graphitic carbon nitride and compare them with PANI-NFs. This type of property shown by the conductive polymer is amazing. The density functional theory is used to verify the stability and the mode of adsorption of the PANI NFs-TMB composite, which corroborates the experimental results. Furthermore, the current nanozyme demonstrated a significant ability to kill both Gram-negative and Gram-positive bacteria as well as effectively destroy biofilms under physiological conditions. We believe that this work provides the motivation to create a link between optoelectronics and biological activity in the near future.

Nanoantioxidants: Pioneer Types, Advantages, Limitations, and Future Insights

Free radicals are generated as byproducts of normal metabolic processes as well as due to exposure to several environmental pollutants. They are highly reactive species, causing cellular damage and are associated with a plethora of oxidative stress-related diseases and disorders. Antioxidants can control autoxidation by interfering with free radical propagation or inhibiting free radical formation, reducing oxidative stress, improving immune function, and increasing health longevity. Antioxidant functionalized metal nanoparticles, transition metal oxides, and nanocomposites have been identified as potent nanoantioxidants. They can be formulated in monometallic, bimetallic, and multi-metallic combinations via chemical and green synthesis techniques. The intrinsic antioxidant properties of nanomaterials are dependent on their tunable configuration, physico-chemical properties, crystallinity, surface charge, particle size, surface-to-volume ratio, and surface coating. Nanoantioxidants have several advantages over conventional antioxidants, involving increased bioavailability, controlled release, and targeted delivery to the site of action. This review emphasizes the most pioneering types of nanoantioxidants such as nanoceria, silica nanoparticles, polydopamine nanoparticles, and nanocomposite-, polysaccharide-, and protein-based nanoantioxidants. This review overviews the antioxidant potential of biologically synthesized nanomaterials, which have emerged as significant alternatives due to their biocompatibility and high stability. The promising nanoencapsulation nanosystems such as solid lipid nanoparticles, nanostructured lipid carriers, and liposome nanoparticles are highlighted. The advantages, limitations, and future insights of nanoantioxidant applications are discussed.

Phytoantioxidant Functionalized Nanoparticles: A Green Approach to Combat Nanoparticle-Induced Oxidative Stress

Nanotechnology is gaining significant attention, with numerous biomedical applications. Silver in wound dressings, copper oxide and silver in antibacterial preparations, and zinc oxide nanoparticles as a food and cosmetic ingredient are common examples. However, adverse effects of nanoparticles in humans and the environment from extended exposure at varied concentrations have yet to be established. One of the drawbacks of employing nanoparticles is their tendency to cause oxidative stress, a significant public health concern with life-threatening consequences. Cardiovascular, renal, and respiratory problems and diabetes are among the oxidative stress-related disorders. In this context, phytoantioxidant functionalized nanoparticles could be a novel and effective alternative. In addition to performing their intended function, they can protect against oxidative damage. This review was designed by searching through various websites, books, and articles found in PubMed, Science Direct, and Google Scholar. To begin with, oxidative stress, its related diseases, and the mechanistic basis of oxidative damage caused by nanoparticles are discussed. One of the main mechanisms of action of nanoparticles was unearthed to be oxidative stress, which limits their use in humans. Secondly, the role of phytoantioxidant functionalized nanoparticles in oxidative damage prevention is critically discussed. The parameters for the characterization of nanoparticles were also discussed. The majority of silver, gold, iron, zinc oxide, and copper nanoparticles produced utilizing various plant extracts were active free radical scavengers. This potential is linked to several surface fabricated phytoconstituents, such as flavonoids and phenols. These phytoantioxidant functionalized nanoparticles could be a better alternative to nanoparticles prepared by other existing approaches.

Antioxidants: Classification, Natural Sources, Activity/Capacity Measurements, and Usefulness for the Synthesis of Nanoparticles

Natural extracts are the source of many antioxidant substances. They have proven useful not only as supplements preventing diseases caused by oxidative stress and food additives preventing oxidation but also as system components for the production of metallic nanoparticles by the so-called green synthesis. This is important given the drastically increased demand for nanomaterials in biomedical fields. The source of ecological technology for producing nanoparticles can be plants or microorganisms (yeast, algae, cyanobacteria, fungi, and bacteria). This review presents recently published research on the green synthesis of nanoparticles. The conditions of biosynthesis and possible mechanisms of nanoparticle formation with the participation of bacteria are presented. The potential of natural extracts for biogenic synthesis depends on the content of reducing substances. The assessment of the antioxidant activity of extracts as multicomponent mixtures is still a challenge for analytical chemistry. There is still no universal test for measuring total antioxidant capacity (TAC). There are many in vitro chemical tests that quantify the antioxidant scavenging activity of free radicals and their ability to chelate metals and that reduce free radical damage. This paper presents the classification of antioxidants and non-enzymatic methods of testing antioxidant capacity in vitro, with particular emphasis on methods based on nanoparticles. Examples of recent studies on the antioxidant activity of natural extracts obtained from different species such as plants, fungi, bacteria, algae, lichens, actinomycetes were collected, giving evaluation methods, reference antioxidants, and details on the preparation of extracts.

Preservative potential of biosynthesized silver nanoparticles: prevention of xylem occlusion and microbial proliferation at postharvest stage of preservation

The purpose of the current study was to determine the appropriate genotype and concentration of biosynthesized silver nanoparticles effectual in preserving mulberry leaves at the postharvest stage. The preservative effect of silver nanoparticles was determined by their potentiality to prevent xylem blockage, chlorophyll content retention and inhibition of microbial proliferation within a preservative solution. For synthesizing silver nanoparticles, a blend of 10-3 M silver nitrate and S1 genotype of the mulberry leaf was found to be most effective. Silver nanoparticles at 6 ppm were observed to be the least effective concentration for preserving mulberry leaves for at least 7 days at the postharvest stage, as evident from physical texture and retention of chlorophyll content. Biosynthesized silver nanoparticles showed negative microbial count during the course of preservation as evident from no colony-forming unit (CFU) until the last day of preservation, while conventional preservative silver nitrate showed traces of CFU on a nutrient agar plate. Besides, these leaves preserved in nanosilver solution showed an almost negligible number of xylem blockage in the petiole, almost equivalent to the blockage nature of fresh leaves caused by the deposition of macromolecules like protein, lignin and suberin. Nanosilver- and silver nitrate-preserved leaves also displayed insignificant accumulation of reactive oxygen species (ROS) and greater retention of membrane integrity than leaves preserved in normal distilled water. Nanosilver solution showed greater durability of preserving mulberry leaves than conventional floral preservative silver nitrate, useful for feeding silkworm larvae during the rainy season.

Antioxidant Functionalized Nanoparticles: A Combat against Oxidative Stress

Numerous abiotic stresses trigger the overproduction of reactive oxygen species (ROS) that are highly toxic and reactive. These ROS are known to cause damage to carbohydrates, DNA, lipids and proteins, and build the oxidative stress and results in the induction of various diseases. To resolve this issue, antioxidants molecules have gained significant attention to scavenge these free radicals and ROS. However, poor absorption ability, difficulty in crossing the cell membranes and degradation of these antioxidants during delivery are the few challenges associated with both natural and synthetic antioxidants that limit their bioavailability. Moreover, the use of nanoparticles as an antioxidant is overlooked, and is limited to a few nanomaterials. To address these issues, antioxidant functionalized nanoparticles derived from various biological origin have emerged as an important alternative, because of properties like biocompatibility, high stability and targeted delivery. Algae, bacteria, fungi, lichens and plants are known as the producers of diverse secondary metabolites and phenolic compounds with extraordinary antioxidant properties. Hence, these compounds could be used in amalgamation with biogenic derived nanoparticles (NPs) for better antioxidant potential. This review intends to increase our knowledge about the antioxidant functionalized nanoparticles and the mechanism by which antioxidants empower nanoparticles to combat oxidative stress.