Chemotactic assay for biological effects of silver nanoparticles

A method is proposed for assessing the biocidal efficacy of water-dispersed nanoparticles of silver. It is based on negative chemotaxis of the plasmodia of the slime mold Physarum polycephalum. Biocidal and repellent effects were compared for silver nanoparticles, Ag⁺ ions, and AOT in solution and in the agar gel. In such characteristics as increasing the period of auto-oscillations of contractile activity, decreasing the area of spreading on substrate, and substrate preference in spatial tests, silver nanoparticles proved to be substantially more effective than Ag⁺ and AOT. The lethal concentrations of the nanoparticles were close to those found earlier for bacteria and viruses. The chemotactic tests allow quantitative assessment of the biological reaction and monitoring its dynamics; in resolution, they are superior to the tests based on the lethal action of biocidal agents.     

Influence of strong bases on the synthesis of silver nanoparticles (AgNPs) using the ligninolytic fungi Trametes trogii

Silver nanoparticles (AgNPs) were biosynthesized using fungal extract of Trametes trogii, a white rot basidiomycete involved in wood decay worldwide, which produces several ligninolytic enzymes. According to previous studies using fungi, enzymes are involved in nanoparticles synthesis, through the so-called green synthesis process, acting as reducing and capping agents. Understanding which factors could modify nanoparticles’ shape, size and production efficiency is relevant. The results showed that under the protocol used in this work, this strain of Trametes trogii is able to synthesize silver nanoparticles with the addition of silver nitrate (AgNO₃) to the fungal extract obtained with an optimal incubation time of 72 h and pH 13, using NaOH to adjust pH. The progress of the reaction was monitored using UV–visible spectroscopy and synthesized AgNPs was characterized by scanning electron microscope (SEM), through in-lens and QBDS detectors, and energy-dispersive X-ray spectroscopy (EDX). Additionally, SPR absorption was modeled using Mie theory and simple nanoparticles and core-shell configurations were studied, to understand the morphology and environment of the nanoparticles. This protocol represents a simple and cheap synthesis in the absence of toxic reagents and under an environmentally friendly condition.     

Synergistic antibacterial activity of carvacrol loaded chitosan nanoparticles with Topoisomerase inhibitors and genotoxicity evaluation

The increasing prevalence of antibiotic resistant bacteria is a significant healthcare crisis with substantial socioeconomic impact on global community. The development of new antibiotics is both costly and time-consuming prompting the exploration of alternative solutions such as nanotechnology which represents opportunities for targeted drug delivery and reduced MIC. However, concerns have arisen regarding genotoxic effects of nanoparticles on human health necessitating an evaluation of nanoparticle induced DNA damage.This study aimed to investigate the antibacterial potential of already prepared, characterized chitosan nanoparticles loaded with carvacrol and their potential synergism with Topoisomerase II inhibitors against S. aureus, E. coli and S. typhi using agar well diffusion, microdilution and checkerboard method. Genotoxicity was assessed through comet assay.Results showed that both alone and drug combinations of varying concentrations exhibited greater zones of inhibition at higher concentrations. Carvacrol nanoparticles combined with ciprofloxacin and doxorubicin significantly reduced MIC compared to the drugs used alone. The MIC₅₀ values for ciprofloxacin were 35.8 µg/ml, 48.74 µg/ml, 35.57 µg/ml while doxorubicin showed MIC₅₀ values of 20.79 µg/ml, 34.35 µg/ml, 25.32 µg/ml against S. aureus, E. coli and S. typhi respectively. The FICI of ciprofloxacin and doxorubicin with carvacrol nanoparticles found ≤ 0.5 Such as 0.44, 0.44,0.48 for ciprofloxacin and 0.45, 0.45, 0.46 for doxorubicin against S. aureus, E. coli and S. typhi respectively revealed the synergistic effect. The analysis of comet assay output images showed alteration of DNA at high concentrations.Our results suggested that carvacrol nanoparticles in combination with Topoisomerase inhibitors may prevent and control the emergence of resistant bacteria with reduced dose.     

Artificial nanovesicles for dsRNA delivery in spray-induced gene silencing for crop protection

Spray-induced gene silencing (SIGS) is an innovative and eco-friendly technology where topical application of pathogen gene-targeting RNAs to plant material can enable disease control. SIGS applications remain limited because of the instability of RNA, which can be rapidly degraded when exposed to various environmental conditions. Inspired by the natural mechanism of cross-kingdom RNAi through extracellular vesicle trafficking, we describe herein the use of artificial nanovesicles (AVs) for RNA encapsulation and control against the fungal pathogen, Botrytis cinerea. AVs were synthesized using three different cationic lipid formulations, DOTAP + PEG, DOTAP and DODMA, and examined for their ability to protect and deliver double stranded RNA (dsRNA). All three formulations enabled dsRNA delivery and uptake by B. cinerea. Further, encapsulating dsRNA in AVs provided strong protection from nuclease degradation and from removal by leaf washing. This improved stability led to prolonged RNAi-mediated protection against B. cinerea both on pre- and post-harvest plant material using AVs. Specifically, the AVs extended the protection duration conferred by dsRNA to 10 days on tomato and grape fruits and to 21 days on grape leaves. The results of this work demonstrate how AVs can be used as a new nanocarrier to overcome RNA instability in SIGS for crop protection.     

Nano-biotechnology in tumour and cancerous disease: A perspective review

In recent years, drug manufacturers and researchers have begun to consider the nanobiotechnology approach to improve the drug delivery system for tumour and cancer diseases. In this article, we review current strategies to improve tumour and cancer drug delivery, which mainly focuses on sustaining biocompatibility, biodistribution, and active targeting. The conventional therapy using cornerstone drugs such as fludarabine, cisplatin etoposide, and paclitaxel has its own challenges especially not being able to discriminate between tumour versus normal cells which eventually led to toxicity and side effects in the patients. In contrast to the conventional approach, nanoparticle-based drug delivery provides target-specific delivery and controlled release of the drug, which provides a better therapeutic window for treatment options by focusing on the eradication of diseased cells via active targeting and sparing normal cells via passive targeting. Additionally, treatment of tumours associated with the brain is hampered by the impermeability of the blood–brain barriers to the drugs, which eventually led to poor survival in the patients. Nanoparticle-based therapy offers superior delivery of drugs to the target by breaching the blood–brain barriers. Herein, we provide an overview of the properties of nanoparticles that are crucial for nanotechnology applications. We address the potential future applications of nanobiotechnology targeting specific or desired areas. In particular, the use of nanomaterials, biostructures, and drug delivery methods for the targeted treatment of tumours and cancer are explored.     

Rare earth cerium oxide nanoparticles attenuated liver fibrosis in bile duct ligation mice model

Liver fibrosis is one of the major liver complications which eventually progresses to liver cirrhosis and liver failure. Cerium oxide nanoparticles, also known as nanoceria (NC) are nanoparticles with potential antioxidant and anti-inflammatory activities. Herein, we evaluated the hepatoprotective and anti-fibrotic effects of nanoceria (NC) against bile duct ligation (BDL) induced liver injury. NC were administered i.p. for 12 days (0.5 and 2 mg/kg) to C57BL/6J mice. The biochemical markers of liver injury, oxidative and nitrosative stress markers, inflammatory cytokines were evaluated. Fibrosis assessment and mechanistic studies were conducted to assess the hepatoprotective effects of NC. Administration of NC proved to significantly ameliorate liver injury as evident by reduction in SGOT, SGPT, ALP and bilirubin levels in the treated animals. NC treatment significantly reduced the hydroxyproline levels and expression of fibrotic markers. In summary, our findings establish the hepatoprotective and anti-fibrotic effects of NC against BDL induced liver injury and liver fibrosis. These protective effects were majorly ascribed to their potential ROS inhibition and antioxidant activities through catalase, superoxide dismutase (SOD)-mimetic properties and auto-regenerating capabilities.     

Lipid Production,Oxidative Status,Antioxidant Enzymes and Photosynthetic Efficiency of <i>Coccomyxa chodatii</i> SAG 216-2 in Response to Calcium Oxide Nanoparticles

The extensive use of nanoparticles (NPs) in diverse applications causes their localization to aquatic habitats, affecting the metabolic products of primary producers in aquatic ecosystems, such as algae. Synthesized calcium oxide nanoparticles (CaO NPs) are of the scarcely studied NPs. Thus, the current work proposed that the exposure to CaO NPs may instigate metabolic pathway to be higher than that of normally growing algae, and positively stimulate algal biomass. In this respect, this research was undertaken to study the exposure effect of CaO NPs (0, 20, 40, 60, 80, and 100 µg mL⁻¹ ) on the growth, photosynthesis, respiration, oxidative stress, antioxidants, and lipid production of the microalga Coccomyxa chodatii SAG 216-2. The results showed that the algal growth concomitant with chlorophyll content, photosynthesis, and calcium content increased in response to CaO NPs. The contents of biomolecules such as proteins, amino acids, and carbohydrates were also promoted by CaO NPs with variant degrees. Furthermore, lipid production was enhanced by the applied nanoparticles. CaO NPs induced the accumulation of hydrogen peroxide, while lipid peroxidation was reduced, revealing no oxidative behavior of the applied nanoparticles on alga. Also, CaO NPs have a triggering effect on the antioxidant enzymes such as superoxide dismutase, catalase, ascorbate peroxidase, and guaiacol peroxidase. The results recommended the importance of the level of 60 µg mL⁻¹ CaO NPs on lipid production (with increasing percentage of 65% compared to control) and the highest dry matter acquisition of C. chodatii. This study recommended the feasibility of an integrated treatment strategy of CaO NPs in augmenting biomass, metabolic up-regulations, and lipid accumulation in C. chodatii.     

Exploring the Therapeutic Properties of Alga-Based Silver Nanoparticles: Anticancer,Antibacterial, and Free Radical Scavenging Capabilities

The current study was designed to evaluate the antioxidant, anticancer and antimicrobial activities of silver nanoparticles (AgNPs) biosynthesized by Spirulina platensis extract. The biosynthesized silver nanoparticles were characterized using Fourier transform infrared (FT-IR) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. The antioxidant activity of the biosynthesized AgNPs were determined via DPPH radical scavenging assay while its anticancer activity was determined using the MTT assay. The antimicrobial activity of the biosynthesized AgNPs were analyzed by disc diffusion method. Spirulina platensis acts as a reducing and capping agent. The efficacy of silver nanoparticles (AgNPs) in inhibiting the growth of Gram-negative bacteria, specifically Acetobacter, Klebsiella, Proteus vulgaris, and Pseudomonas aeruginosa, was assessed by the utilisation of the diffusion method. The study aimed to evaluate the efficacy of biosynthesized silver nanoparticles (AgNPs) against many strains of Pseudomonas aeruginosa bacteria. The findings of the study revealed that when administered in doses of 50 μl, 75 μl, and 100 μl, the largest observed zone of inhibition corresponded to measurements of 10.5 mm, 14 mm, and 16 mm, respectively. A zone of inhibition with dimensions of 8 mm, 10.5 mm, and 12 mm was detected during testing against Acetobacter at concentrations of 50 μl, 75 μl, and 100 μl, respectively. The findings also indicate that there is a positive correlation between the concentration of AgNP and the DPPH scavenging ability of silver nanoparticles. The percentage of inhibition observed at concentrations of 500 μg/ml, 400 μg/ml, 300 μg/ml, 200 μg/ml, and 100 μg/ml were recorded as 80±1.98, 61±1.98, 52±1.5, 42±1.99, and 36±1.97, respectively. In addition, it was observed that the silver nanoparticles exhibited the greatest antioxidant activity at a concentration of 500 g/ml, with a measured value of 80.89±1.99. The IC-50 values, representing the inhibitory concentration required to achieve 50 % inhibition, were found to be 8.16, 19.15, 30.14, 41.13, and 63.11 at inhibition levels of 36±1.97, 42±1.99, 52±1.5, 61±1.98, and 80±1.98, respectively.     

Analysis of the activation of acetylcholinesterase by carbon nanoparticles using a monolithic immobilized enzyme microreactor: role of the water molecules in the active site gorge

A biochromatographic system was used to study the direct effect of carbon nanoparticles (CNPs) on the acetylcholinesterase (AChE) activity. The AChE enzyme was covalently immobilized on a monolithic CIM-disk via its NH₂ residues. Our results showed an increase in the AChE activity in presence of CNPs. The catalytic constant (k_cat) was increased while the Michaelis constant (K_m) was slightly decreased. This indicated an increase in the enzyme efficiency with increase of the substrate affinity to the active site. The thermodynamic data of the activation mechanism of the enzyme, i.e. ΔH* and ΔS*, showed no change in the substrate interaction mechanism with the anionic binding site. The increase of the enthalpy (ΔH*) and the entropy (ΔS*) with decrease in the free energy of activation (Ea) was related to structural conformation change in the active site gorge. This affected the stability of water molecules in the active site gorge and facilitated water displacement by substrate for entering to the active site of the enzyme.