Exploring sustainable management by using green nano-silver to combat three post-harvest pathogenic fungi in crops.

Global crop protection and food security have become critical issues to achieve the 'Zero Hunger' goal in recent years, as significant crop damage is primarily caused by biotic factors. Applying nanoparticles in agriculture could enhance crop yield. Nano-silver, or AgNPs, have colossal importance in many fields like biomedical, agriculture, and the environment due to their antimicrobial potential. In this context, nano-silver was fabricated by Citrus medica L. (Cm) fruit juice, detected visually and by UV-Vis spectrophotometric analysis. Further, AgNPs were characterized by advanced techniques. UV-Vis spectroscopic analysis revealed absorbance spectra at around 487 nm. The zeta potential measurement value was noted as -23.7 mV. Spectral analysis by FT-IR proved the capping of the acidic groups. In contrast, the XRD analysis showed the Miller indices like the face-centered cubic (fcc) crystalline structure. NTA revealed a mean size of 35 nm for nano-silver with a 2.4 × 108 particles mL-1 concentration. TEM analysis demonstrated spherical Cm-AgNPs with 20-30 nm sizes. The focus of this research was to evaluate the antifungal activity of biogenic AgNPs against post-harvest pathogenic fungi, including Aspergillus niger, A. flavus, and Alternaria alternata. The Cm-AgNPs showed significant antifungal activity in the order of A. niger > A. flavus > A. alternata. The biogenic Cm-AgNPs can be used for the inhibition of toxigenic fungi.

Biogenic Synthesis of Fluorescent Carbon Dots (CDs) and Their Application in Bioimaging of Agricultural Crops.

Fluorescent nanoparticles have a transformative potential for advanced sensors and devices for point-of-need diagnostics and bioimaging, bypassing the technical burden of meeting the assay performance requirements. Carbon dots (CDs) are rapidly emerging carbon-based nanomaterials. Regardless of their fate, they will find increasing applications. In this study, a simple approach for synthesizing CDs from fruit peels was developed. The CDs were fabricated from Annona squamosa (L.) peels using a carbonization technique through microwave-assisted hydrothermal digestion at temperatures around 200 °C. Synthesized CDs were detected using a UV transilluminator for the preliminary confirmation of the presence of fluorescence. UV-Vis spectrophotometry (absorbance at 505 nm) analysis, zeta potential measurement (-20.8 mV), nanoparticles tracking analysis (NTA) (average size: 15.4 nm and mode size: 9.26 nm), photoluminescence, and Fourier transform infrared (FT-IR) analysis were used to identify the capping functional groups on the CDs. The total quantum yield exhibited was 8.93%, and the field emission scanning electron microscopy (FESEM) showed the size range up to 40 nm. The germinating mung bean (Vigna radiata (L.)) seeds were incubated with biogenically synthesized CDs to check the absorption of CDs by them. The fluorescence was observed under a UV-transilluminator in the growing parts of seeds, indicating the absorption of CDs during the germination, development, and growth. These fluorescent CDs could be used as a bioimaging agent. This novel method of synthesizing CDs was found to be eco-friendly, rapid, and cost-effective.

Management of Phytophthora parasitica causing gummosis in citrus using biogenic copper oxide nanoparticles.

AIM: The main aim of the present study was to develop nanotechnology-based solutions for the management of a fungus, Phytophthora parasitica causing gummosis in citrus. METHODS AND RESULTS: Biogenic copper nanoparticles (CuONPs) were synthesized using two different biocontrol agents, Pseudomonas fluorescens and Trichoderma viride and characterized using different analytical techniques. Furthermore, in vitro (at the concentrations of 10, 15, 30, 50, 70, 100 and 150 mg/L) and in vivo (at the concentration of 100 mg/L) activities of these nanoparticles were evaluated for their antifungal efficacy against P. parasitica. The results obtained confirmed the synthesis of irregular-shaped CuONPs having a size in the range 40-100 nm in case of P. fluorescens, whereas, spherical CuONPs in the size range 20-80 were recorded in case of T. viride. As far as the in vitro antifungal efficacies of both these CuONPs is concerned, the maximum percent growth inhibition was observed in case of CuONPs synthesized from T. viride compared to CuONPs from P. fluorescens. However, in case of in vivo antifungal efficacies, CuONPs synthesized from T. viride showed the activity significantly higher than the conventionally used Bordeaux mixture. CONCLUSIONS: It can be concluded that biosynthesized CuONPs can be effectively used as a potential fungicide against P. parasitica. SIGNIFICANCE AND IMPACT OF THE STUDY: The application of nanoparticles having antifungal activities can be used as alternative fungicides to the conventional chemical fungicides. It has the potential to revolutionize the existing management strategies available for plant pathogenic fungi.

Assessment of in vitro antimicrobial efficacy of biologically synthesized metal nanoparticles against pathogenic bacteria.

The microbial infections due to biofilm forming bacterial pathogens are very common in human subjects. The intensive application of antibiotics in integrated disease management strategy has led to increased multidrug resistance incommon pathogens. Thus, indicating need of developing an alternative method for the control of these multidrug resistant pathogens. Present study involves the Moringa oleifera aqueous extract mediated biological synthesis of silver (Ag nanoparticles (NPs)- Avg. size 82.5 nm; zeta potential = -27.9 mV), copper oxide (CuONPs- Avg. size 61 nm; zeta potential = -19.3 mV), iron oxide (FeONPs- Avg. size 83.3 nm; zeta potential = -9.37 mV) and alumina (AlONPs- Avg. size 87.3 nm; zeta potential = -10.9 mV) nanoparticles. Biological nanoparticles were detected by visual observation, spectrophotometric detection followed by zeta potential analysis, nanoparticle tracking analysis, Fourier transform infrared spectrometry and X-ray diffraction analysis. Nanoparticles were further evaluated for their in vitro antimicrobial potential, membrane damage effectiveness, biofilm inhibition activity by MTT assay. Nanoparticles were assessed against human pathogens viz. two Gram-positive (Bacillus subtilis MTCC 441 and Staphylococcus haemolyticus MTCC 3383) and two Gram-negative bacteria (Enterobacter aerogenes MTCC 111 and Salmonella enterica ser. Typhi MTCC 8767). The nanoparticles exhibited akin activity pattern against all pathogens studied i.e. AgNPs > CuONPs > AlONPs > FeONPs. Tested nanoparticles registered lower MIC values and more intensified growth inhibition against Gram-negative bacteria compared to their Gram-positive counterparts. These results pointed out that the M. oleifera mediated nanoparticles can be prospectivelyutilized in the development of alternative antimicrobials against diverse bacterial infections.

A novel nano-sulphur and essential oil-based room freshener

Introducción: Alternaria spp y Candida spp. son hongos patógenos de ambientes interiores como la casa, la oficina, el aula, etc., causan enfermedades como asma crónica e infecciones sistémicas en individuos inmunodeprimidos a través de la secreción de diversas sustancias tóxicas. Los ambientadores a base de productos químicos disponibles comercialmente que se utilizan para controlar la carga de hongos en el ambiente interior no son beneficiosos para la salud humana. Objetivo: proporcionar una alternativa viable en forma de enfoque basado en nanopartículas para el manejo de hongos transmitidos por el aire. Metodología: aislamiento, identificación microscópica y bioquímica de hongos de interior; Síntesis de nanopartículas de azufre (SNP) mediadas por Azadirachta indica, su detección y caracterización; y evaluación in vitro de SNP contra hongos aislados presentes en el ambiente interior. Resultado: Los hongos aislados se identificaron como especies de Alternaria spp y Candida spp. Los SNP mostraron máximos de absorbancia a 291 nm. El análisis NTA mostró un tamaño medio de 188,4 nm y un potencial zeta de -4,94 mV, lo que representa una síntesis de SNP estables. El patrón XRD confirmó la naturaleza cristalina cúbica centrada en la cara de los SNP. El espectro FTIR representó la presencia de compuestos polihidroxilo, nitrilo, ceto, aromáticos y carboxílicos que estabilizaron los SNP. Los ensayos antifúngicos demostraron la actividad significativa de los SNP formulados y del ambientador infundido con aceite de eucalipto. Conclusión: Los SNP mediados por A. indica se pueden aplicar en la formulación y fabricación de un ambientador ecológico para el manejo de hongos patógenos de interior como Alternaria spp y Candida spp.

Introduction: Alternaria spp. and Candida spp. are the main fungal pathogen of indoor environment like house, office, classroom, etc. These may cause various diseases and infections like systemic infections, or chronic asthma in immunocompromised individuals through secretion of various toxic substances. Chemical-based commercially available room fresheners used to control the fungal load of indoor environment are not beneficial to human health. Objective: was to provide viable alternative in the form of nanoparticle-based approach for the management of air-borne fungi. Methodology: The present study primarily focuses on the isolation, microscopic and biochemical identification of indoor fungi; Azadirachta indica-mediated sulphur nanoparticles (SNPs) synthesis, their detection and characterization; and in vitro assessment of SNPs against isolated fungi present in indoor environment. Result: The isolated fungi were identified as Alternaria spp and Candida spp. The SNPs showed absorbance maxima at 291 nm. NTA analysis showed average size of 188.4 nm, and zeta potential of -4.94 mV which represented synthesis of stable SNPs. XRD pattern confirmed the face centered cubic, crystalline nature of SNPs. FTIR spectrum depicted the presence of polyhydroxyl, nitrile, keto, aromatic and carboxylic compounds which stabilized the SNPs. The antifungal assays demonstrated the significant activity of the formulated SNPs and eucalyptus oil infused air freshener. Conclusion: It can be concluded that A. indica-mediated SNPs can be applied in the formulation and manufacture of an ecofriendly air freshener for the management of indoor fungal pathogens like Alternaria spp. and Candida spp.

Three Phoma spp. synthesised novel silver nanoparticles that possess excellent antimicrobial efficacy.

The authors report extracellular mycosynthesis of silver nanoparticles (AgNPs) by Phoma capsulatum, Phoma putaminum and Phoma citri. The AgNPs thus synthesised were characterised by UV-visible spectrophotometer, Fourier transform infrared spectroscopy, Nanosight LM20 and transmission electron microscopy, which confirmed the synthesis of mostly spherical and polydisperse nanoparticles capped with proteins. The size of AgNPs was found in the range of 10-80 , 5-80 and 5-90 nm with an average size of 31.85, 25.43 and 23.29 nm by P. capsulatum, P. putaminum and P. citri, respectively. Further, potential antimicrobial activity was reported against Aspergillus niger, Candida albicans, Salmonella choleraesuis, Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli. The lowest minimal inhibitory concentration (MIC) (0.85 µg/ml) was reported for AgNPs synthesised from P. citri against S. choleraesuis. However, AgNPs synthesised from P. capsulatum showed the highest MIC (10.62 µg/ml) against S. choleraesuis, P. aeruginosa and E. coli (clinical isolate). The same MIC values (10.62 µg/ml) were also reported against P. aeruginosa and both clinical and standard isolates of E. coli for AgNPs synthesised from P. citri. It was also observed that all the silver nanoparticles showed remarkable antifungal and antibacterial activity against these tested pathogens as compared with the commercially available antifungal and antibacterial agents.

Curcumin nanoparticles: physico-chemical fabrication and its in vitro efficacy against human pathogens.

Curcumin is one of the polyphenols, which has been known for its medicinal use since long time. Curcumin shows poor solubility and low absorption, and therefore, its use as nanoparticles is beneficial due to their greater solubility and absorption. The main aim of the present study was the formation of curcumin nanoparticles (Nano curcu), evaluation of their antibacterial activity against human pathogenic bacteria and formulation of Nano curcu-based cream. We synthesized Nano curcu by sonication method. The synthesis of Nano curcu was assessed for their solubility in water and by UV-visible spectrophotometry. Further, the nanoparticles were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, nanoparticle tracking and analysis, and zeta potential analysis. In vitro antibacterial activity of Nano curcu was evaluated against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The cream containing Nano curcu was found to be effective against human bacterial pathogens and hence can be used for treatment of bacterial diseases.

Lawsonia inermis-mediated synthesis of silver nanoparticles: activity against human pathogenic fungi and bacteria with special reference to formulation of an antimicrobial nanogel.

Lawsonia inermis mediated synthesis of silver nanoparticles (Ag-NPs) and its efficacy against Candida albicans, Microsporum canis, Propioniabacterium acne and Trichophyton mentagrophytes is reported. A two-step mechanism has been proposed for bioreduction and formation of an intermediate complex leading to the synthesis of capped nanoparticles was developed. In addition, antimicrobial gel for M. canis and T. mentagrophytes was also formulated. Ag-NPs were synthesized by challenging the leaft extract of L. inermis with 1 mM AgNO3. The Ag-NPs were characterized by Ultraviolet-Visible (UV-Vis) spectrophotometer and Fourier transform infrared spectroscopy (FTIR). Transmission electron microscopy (TEM), nanoparticle tracking and analysis sytem (NTA) and zeta potential was measured to detect the size of Ag-NPs. The antimicrobial activity of Ag-NPs was evaluated by disc diffusion method against the test organisms. Thus these Ag-NPs may prove as a better candidate drug due to their biogenic nature. Moreover, Ag-NPs may be an answer to the drug-resistant microorganisms.

Fungus-mediated synthesis of gold nanoparticles and standardization of parameters for its biosynthesis.

We report the extracellular biosynthesis of gold nanoparticles (AuNPs) using a fungus Fusarium acuminatum. Mycosynthesis of Au-NPs was carried out by challenging the fungal cells filtrate with HAuCl 4 solution (1 mM), as nanoparticles synthesizing enzyme secrete extracellularly by the fungi. The AuNPs were characterized with the help of UV-Visible spectrophotometer, Fourier Transform Infrared spectroscopy, Zeta Potential, X-ray diffraction (XRD) and Transmission electron microscopy (TEM). We observed absorbance peak in between 520 nm-550 nm corresponding to the surface plasmon absorbance of the gold nanoparticles. The nanoparticles synthesized in the present investigation were found to be capped by proteins. XRD results showed that the distinctive formation of crystalline gold nanoparticles in the solution. The spherical and polydispersed AuNPs in the range 8 to 28 nm with average size of 17 nm were observed by TEM analysis. We also standardized the parameters like the effect of pH, temperature and salt concentration on the biosynthesis of gold nanoparticles. It was found that acidic pH, 1 mM salt concentration and 37 (°)C temperature were found to be optimum for the synthesis of Au-NPs. Therefore, the present study introduces the easy, better and cheaper method for biosynthesis of AuNPs.

Rapid synthesis of silver nanoparticles from Fusarium oxysporum by optimizing physicocultural conditions.

Synthesis of silver nanoparticles (SNPs) by fungi is emerging as an important branch of nanotechnology due to its ecofriendly, safe, and cost-effective nature. In order to increase the yield of biosynthesized SNPs of desired shape and size, it is necessary to control the cultural and physical parameters during the synthesis. We report optimum synthesis of SNPs on malt extract glucose yeast extract peptone (MGYP) medium at pH 9-11, 40-60°C, and 190.7 Lux and in sun light. The salt concentrations, volume of filtrate and biomass quantity were found to be directly proportional to the yield. The optimized conditions for the stable and rapid synthesis will help in large scale synthesis of monodispersed SNPs. The main aim of the present study was to optimize different media, temperature, pH, light intensity, salt concentration, volume of filtrate, and biomass quantity for the synthesis of SNPs by Fusarium oxysporum.

Green synthesis of silver nanoparticles using white sugar.

Till date several methods of chemical synthesis of silver nanoparticles (AgNps) are known. Most of the protocol dealing with the chemical synthesis of AgNps involves high pressure, temperature, energy and technical skills. Thus, a method with much greener approach is the need of the hour. Accordingly, the authors have developed a method that is cost-effective, energy-efficient and easy method for the synthesis of AgNps. The AgNps were synthesised by using white sugar and sodium hydroxide (NaOH) in the presence of sunlight. These nanoparticles were characterised by visual observation, ultraviolet-visible (UV-vis) spectrophotometry, Fourier transform infrared (FTIR), nanoparticle tracking and analysis (NTA) and transmission electron microscopy (TEM). The effect of NaOH on the rate of AgNps synthesis was also studied. Formation of AgNps was primarily detected by change in colour of reaction mixture from colourless to yellow after treatment with 1 mM silver salt (AgNO3). UV-vis spectroscopy showed peak at 409 nm. NTA revealed the polydispersed nature of nanoparticles, 15-30 nm in diameter. FTIR showed the presence of gluconic acid as capping agent, which increases the stability of AgNps in the colloids. TEM demonstrated the presence of spherical AgfNps in the range of 10-25 nm. The present method confirms the synthesis of AgNps by using white sugar and NaOH. This method is simple, eco-friendly and economically sustainable, making it amenable to large-scale industrial production of AgNps.