Myconanosomes: Antibacterial, antifungal and immunomodulatory activities of silver nanoparticles synthesized from Alternaria brassicae (KF934409) Faria Fatima1 , Neelam Pathak1 , Sarika Singh2 , Smita Rastogi Ve rma3 and *Preeti Bajpai1 1 2 3 Department of Biosciences, Integral University, Lucknow-226026, India Toxicology Division, Central Drug Research Institute, Lucknow-226031, India Department of Biotechnology, Delhi Technological University, Delhi-110042, India *Corresponding author email: [email protected] Abstract Silver nanoparticles (AgNPs) prepared from Alternaria brassicae may exhibit potential antimicrobial and immunomodulatory activity due to their inimitable character. The purpose of this study was to evaluate their antibacterial activity, antifungal and immunomodulatory efficacy on various pathogenic microorganisms and cell lines (J774 and THP1 α). The characterization of these AgNPs was determined by using differential light scattering, UV-visible spectroscopy and transmission electron microscopic analyses. Mycologically produced AgNPs were found as spherical and irregular shaped measuring size range between 55.4 nm to 70.23 nm. The antimicrobicidal activity of these AgNPs against Staphylococcus aureus, Trichoderma sp. and Fusarium semitectum was evaluated by agar well diffusion method. Results showed that AgNPs inhibit the growth of various bacteria and fungi, which may be due to the disruption of cell membranes, leakage of cytoplasm and DNA degradation. Cytotoxicity analysis of AgNPs on cell lines revealed its dose dependent effect. Moreover, significant increase of intracellular reactive oxygen species was characterized in AgNPs treated cells after 4 hr of incubation. Thus, AgNPs may have a significant advantage over conventional antibiotics as microorganisms are acquiring resistance against the broad range of available antibiotics. In conclusion, study showed that these nanoparticles could be used as an antimicrobial agents as well as cost effective and nontoxic immunomodulatory delivery vehicle. Keywords: A. brassicae; AgNP; antibacterial; antifungal; cytotoxicity; immunomodulatory 1 1. Introduction Myco- nanotechnology is an emerging scientific discipline aimed towards studying the production of nanomaterials or nanostructures with desirable shapes and sizes by fungi. Potential appliances of myco-nanotechnology have fascinated scientist and researchers to contribute in providing incremental solutions through green chemistry approaches for targeted drug delivery. Thus, nano-sized particles have attracted worldwide attention due to their unusual photoelectrochemical, electronic chemical and optical properties. AgNPs offer unique optical, catalytic and disinfectant properties gaining high scientific and commercial interest. They are used in broad range of different products ranging from acting as an antimicrobial agent, coatings of surgical instruments, contraceptive devices, wound dressing and prostheses [9] to the use in food container systems. Besides that, they are highly attractive for creation of advanced functional materials. To meet the wide scope of nanostructures, number of procedure like electrochemical methods, laser ablation method, microwave irradiation method, thermal decomposition may successfully produce pure well-defined nanoparticles. However, these procedures are capital- intensive, dangerous, energy use and often create health hazards due to the usage of toxic chemicals, which lead to production of harmful by-products [12] that makes their use inappropriate within biological systems. The safety of nanomaterials marketed during past decades does not appear to be adequately addressed. There is a persistent requirement to develop new methods which should be safe, nontoxic, reliable, cost effective, and ecofriendly. The new methods should also be able to assess the cytotoxicological safety of current and future nanomaterials under different scenarios. Thus, synthesis of nanoparticles by using bio-organisms like bacteria, fungi, and plant extracts is compatible with the green chemistry principles [14]. Biosynthesis of metal nanoparticles is a kind of bottom up approach where the main reaction is the reduction/oxidation reaction. The enzymes from these microbes possess high redox potential which is usually responsible for reduction of metal compounds into their respective nanopartic ulates (Figure 1) and synthesized nanomaterials would be intervened by biological systems. Recently, resistance to commercially available antimicrobial agents by pathogenic bacteria and fungi has been rising at an alarming rate and has become a severe problem [8]. 2 Fig.1 Schematic representation of reduction of metal ions by fungal secretary proteins In the present study, a phosphate solubilizing fungi was preferred for nanostructure formulation due to their ability to produce large amount of secretary proteins [16]. Numbers of reports have showed the biological synthesis of metal nanoparticles but the potential of a phosphate solubilizing fungi, A. brassicae has not yet been demonstrated. The present investigation is an effort to synthesize AgNPs from A. brassicae (Accession No. KF934409). Moreover, antimicrobials of mycological origin have enormous therapeutic potential therefore, it is the need of time to develop new antimicrobial drugs for the treatment of infectious diseases. 2. Material and methods 2.1 Isolation, screening and characterization of A. brassicae (KF934409) The fungus was isolated from rhizospheric region of Central Institute of Medicinal And Aromatic Plants (CIMAP), Lucknow, India and screened by its phosphate solubilizing ability on Pikovskaya’s medium by using plate assay method [7]. The fungal colonies were subculture on fresh petriplates containing potato dextrose agar (PDA) media and the plates were incubated in inverted position for 72 h at 28 ± 3 C and examine for the halo zones around the colony. Further, the biochemical characterization of the fungus were tested on the basis of morphology of colony, conidial microscopic analysis, solubilization index (SI), cellulose hydrolysis test and starch hydrolysis test according to standard protocols [6]. 3 The fungus was molecularly characterized by using 18S rRNA sequencing where genomic DNA was isolated and subjected to high–fidelity PCR using universal primers i.e. forward primer (5’-GGAAGTAAAAGTCGTAACAAGG-3’) and reverse primer (5’-TCCTCCGCTTATTGATATGC-3’) and analyzed on 1 % agarose gel. The PCR products were sequenced bi-directionally using the forward and reverse primers. Homology between this 18S rDNA sequence and the strains available at the public databases (Genbank, EMBL a nd DDBJ) was determined using BLASTN sequence match routines. The UPGMA (Unweighted Pair Group Mathematical Average) algorithm was used to perform hierarchical cluster analysis [13]. The sequences were aligned using CLUSTALW2 program and its phylogenetic a nd molecular evolutionary analysis were conducted. Sequences analyses were performed by alignment of the partial 18S rRNA gene sequences to those from the GenBank database, using the program BLAST (NCBI BLAST® homepage). The nucleotide sequences of 18S rRN A gene segments determined in this study have been deposited in GenBank database under accession number KF934409. 2.2 Myco-production of AgNPs and its characterization The isolated fungus was grown in MGYP (maltose, glucose, yeast potato broth which comprises of malt extract (0.5 %), glucose (1 %), yeast extract (0.3 %) and peptone (0.5 %). The culture was incubated at 27° C and harvested after 5 days of growth by sieving followed by extensive washing with sterile double-distilled water. Initially 20 g of biomass (wet weight) was transferred to 100 ml deionized water for 48 hr at 27° C in an Erlenmeyer flask and agitated at 150 x rpm for release of secretory proteins. Silver nitrate (1 mM) was added to the Erlenmeyer flasks and the reaction was allowed to progress under dark conditions for production of AgNPs. Time-dependent formation of AgNPs was observed by using ultraviolet- visible spectrophotometer (Beckman DU-20 spectrophotometer). The scanning range was 350-650 nm for AgNPs at a scan speed of 420 nm/min. The data was recorded and analyzed using “UVWinlab” software. 2.2.1 Differential light scattering (DLS) The suspensions of AgNPs was prepared in distilled water (dH2 O) by using a bath-sonicator (ULTRAsonik 57 X, 50/60 Hz, California, USA) prior to size measurements. Dynamic light 4 scattering size measurements were performed with the aid of a Malvern Zeta Sizer Nano ZS (Malvern Instruments, Worcestershire, UK) operating with version 5.03 of the systems Dispersion Technology Software (DTS Nano). The sample s for DLS were equilibrated at 25º C for 3 min before each measurement. The refractive index (RI) of AgNP.dH2 O was 1.330. 2.2.2 Transmission electron microscopy (TEM) The synthesized AgNPs were characterized by TEM analysis. The samples were prepared by placing a drop of synthesized nanoparticles over gold-coated negative grid followed by evaporation of the solvent [22]. TEM analysis was performed on Perkin-Elmer model which was operated at an accelerating voltage of 1000 kV. 2.3 Antibacterial efficacy The antibacterial efficacy of synthesized AgNPs was determined by using the agar well diffusion assay method [4]. Pure cultures of five pathogenic bacteria namely, B. subtilis, B. cereus, S. aureus, E. coli and E. aeroginosa were procured from National Chemical Laboratory, Pune. Bacterial stock cultures were maintained at 4° C on nutrient agar media slants and subculture on nutrient broth media for antibacterial analysis of NPs. 5 mm wells in diameter were prepared and filled with AgNPs with a range of concentrations (10 µM, 50 µM, 100 µM, 150 µM). Each experiment was performed in triplicate and the average zone of inhibition, excluding well was recorded. 1 mM AgNO 3 were used as negative controls. The diameter of such zones of inhibition was measured for each organism and expressed in centimeter. 2.4 Antifungal efficacy Disk diffusion method was used to evaluate the antifungal activity of Terconazole against A. niger, Trichoderma sp. and F. semitectum on PDA. The standard terconazole disks (Fu10; 10 μg/disk) were purchased from Hi-Media (Bangalore, India). To determine the combined effect, each standard paper disk was further imbued with 25 μl of freshly prepared AgNPs with a concentrations range of 10 µM, 50 µM, 100 µM, 200 µM. PDA plates were inoculated with a spore suspension (20 μ l) of the test fungi. Standard antifungal terconazole disks were used as positive control. The terconazole disks were impregnated with AgNPs, placed onto the PDA medium and inoculated with tested fungi. The fungal cell filtrate, used for the synthesis of 5 AgNPs was used as negative control. The cultured plates were incubated at 28 ± 4 C for 7 days. The average inhibition zone, excluding well, for each case was measured. 2.5 Cell lines Human macrophage cell line THP1 α and mouse macrophage cell line J774 was procured from the National Center of Cell Sciences, Pune, India and maintained at Animal Tissue Culture facility of Central Drug Research Institute (CDRI). Cells were cultured in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10 % Foetal bovine serum (FBS) and 1% antibiotic and antimycotic solution (50,000 units/L of penicillin and 50 mg/L of streptomycin) and 2 mM glutamine. Cultures were held in 75 cm culture flasks, at 37˚ C and 5 % CO 2 using standard cell culture methods. 2.5.1 Cytotoxicity assay Cell viability was assessed by using the MTT [3-(4, 5-dimethylthiazol-2-yl)-2, 5diphenyltetrazolium bromide] conversion assay [5]. Thus, 1 x 104 cells/ml were seeded on 96well culture plates and incubated with increasing concentrations of nanoparticles (10 μM, 25 μM, 50 μM, 100 μM, 150 μM and 200 μM) for 24 hr at 37° C in CO 2 incubator. The MTT dye was added to each well and plate was incubated at 37° C for 4 hr. The absorbance of insoluble formazan salts was assessed at 550 nm using Powerwave XS (BIOTEK, USA) spectrophotometer [3]. Data produced were used to plot a dose-reaction curve and the concentration of these metal nanoparticles required to kill 50 % of cell population (IC 50 ) was determined. Cell viability (%) = Mean OD × 100 Control OD 2.5.2 Intracellular reactive oxygen species estimation Intracellular oxidative stress was calculated with the help of 2’, 7’-dichlorofluorescin di-acetate (DCFH-DA), a well-accepted fluorescent marker for study of intracellular hydroperoxides [18]. The experiment was performed according to the protocol described [15] with slight modifications. Primarily, healthy confluent cells were harvested and seeded (1000 cells/well) into black bottomed 96 well plates (Nunc, Denmark) and allowed to adhere for a period of 24 hr 6 prior to exposure. For ROS quantification, both mouse and human macrophage cells were plated and distributed in triplicates. A working stock of 25 µM DCFH-DA in phosphate buffered saline (PBS) was prepared and all test concentrations, unexposed negative controls and positive controls were prepared and exposed to the cells in this working stock. The negative control consisted of the working stock solely a 25 µM DCFH-DA solution in PBS, the positive control consisted of 1 µM hydrogen peroxide (H2 O2 ) in 20 µM DCFH-DA/PBS working stock solution and finally the test concentrations consisted of a continuous range of AgNPs. Lipopolysaccharide (1 µg/ml) was used as a mitogen for stimulation of macrophages as well as comparison of phagocytic activity of stimulated and non-stimulated macrophages. The test concentration for AgNPs was 10µg/ml and the incubation period ranged from 2 hr to 6 hr. The rate of intracellular oxidative stress was monitored by measuring their fluorescence intensity via fluorometer (BIOTEK-FLX800’USA) emission at 520 nm (by 485 nm excitation). 2.6 Statistical analysis All the experiments were conducted in triplicates and results were expressed as mean ± SD. Oneway analysis of variance (ANOVA) with a Dunnett’s test was performed for the multiple comparisons for normally distributed samples with homogenous variance. Statistically significant differences were set at p < 0.05. 3 Results 3.1 Screening and fungal characterization The rhizospheric sample was collected, serially diluted and plated on Pikovskaya’s media to check their phosphate solubilization efficiency. After 7 d of incubation, a fungal colony was observed, identified, as dark ash colour, looking like cotton having irregular edges and 1.2 cm in diameter. On Pikovskaya’s medium, the transparency of the media is a primary indicator of phosphate solubilization to be visualized as halo zone formation around the colony. Thus among all, the fungal isolate FCK 20 was found as an efficient fungus on the basis of SI, pH and phosphatase enzyme production. This fungus was further characterized morphologically, biochemically and at molecular level. The SI of selected fungus was recorded with size of 2.9 cm in comparison with others strains. Further, colony morphology was analyzed on the Sabouraud agar medium and filamentous structural pattern was analyzed microscopically after 7 lactophenol staining. Moreover, this fungus gave a negative test for starch hydrolysis and cellulose degrading ability. For molecular characterization, the genomic DNA was amplified using 18S rRNA specific primers (ITS 4 and ITS 5). An amplicon of 500 bp was observed on 1 % agarose gel. The DNA sequencing of the amplified product and its BLAST analysis confirmed the fungus as A. brassicae (KF934409). The phylogenetic analysis (Figure 2) revealed the fungus to belong to Pleosporacae family and the genus was Alternaria. Fig. 2 Phylogenetic analysis of A. brassicae (KF934409) 3.2 Synthesis and size estimation of AgNPs AgNPs were mycological produced from A. brassicae (KF934409). 1 mM of silver nitrate were added to the fungal filtrate under magnetic stirring which was used as reducing and stabilizing agent for 1 mM of silver nitrate. Appearance of a brownish color in solution (Figure 3) reflected the formation of AgNPs in the reaction mixture which is due to the surface plasmon resonance, 8 exhibited by the AgNPs. The control sets did not demonstrate any color change under similar experimental conditions. Fig.3 Nanoparticles formation on the basis of colour change due to surface plasmon resonance 3.2.1 Ultraviolet-visible spectrophotometric analysis Ultraviolet- visible spectrophotometer showed no evidence of absorption in the range of 380-750 nm for the fungal extract. Whereas the AgNO 3 exposed fungal extract showed a distinct absorption at around 350 nm and 650 nm, with a peak at 370 nm for AgNPs [Figure 4 (a)]. Fig.4 (a) UV-VIS spectrophotometry of AgNP nanoparticles and 4 (b) DLS spectrum of Ag nanoparticles 3.2.2 Dynamic light analysis (DLS) This technique enables the particle size determination by measuring the random changes in the intensity of light scattered from a suspension or solution. DLS spectra showed an intensity of 9 92.7 nm for AgNPs [Figure 4 (b)]. This size variation is due to oxidation of metal salts into their respective nanoparticles in the presence of enzymes. 3.2.3 Transmission electron microscopic (TEM) analyses The morphology of AgNPs is spherical and the TEM micrographs suggest that particle diameters ranged from 48.4 to 65.23 nm (Figure 5). The dimensions of AgNPs were small enough and imaged as poly dispersed small and large spherical nanoparticles with variable diameter. This was further confirmed by the representative images recorded from the uniformly dispersed dropcoated film of the AgNPs on grid. Fig.5 Transmission electron microscopic analysis of AgNP nanoparticles 3.3 Antibacterial activity of AgNPs The bactericidal activity of AgNPs were studied using the pathogenic strains of bacteria as S. aureus, E. coli, B. subtilis, B. cereus and E. aerogenes using agar well diffusion method. After the incubation time, zone of inhibition (clear zones) were observed against all the tested microbes. The results recorded in centimetres for AgNPs are shown in Figure 6 (a) respectively. The effectiveness of AgNPs could be attributed to the fact that their larger surface area enabled them to have a better contact with the microbial cell wall. This is further supported by the observation that size dependent interaction of AgNPs with bacteria leads to its antibacterial activity [21]. The exact mechanism by which the reaction occurs is still largely unknown. 10 However, some literature proposes that Ag interact with the thiol groups of proteins, which is necessary for microbial respiration ability [10]. Ag might also interact with phosphorus containing compounds like DNA disturbing the replication process or preferably by their attack on the respiratory chain [10]. The direct interaction of Ag with cell membrane of bacteria has also been shown which consequently breaks the membrane. Earlier experimental evidences have also advocated the failure of replication ability by the DNA after treatment with silver ions [17]. The comparative histogram demonstrated that the best antibacterial efficacy of AgNPs was against B. cereus followed by S. aureus. The marked increase in antibacterial activity was demonstrated with increasing concentration of AgNPs [Figure 6 (a)]. In addition, the efficacy of AgNPs was also found to be enhanced in combination with the antibiotic rather than alone. Zone of inhibition (cm) 3.5 E. aerogenes 3 B. subtilis E.coli S. aureus B.cereus 2.5 2 * 1.5 1 0.5 0 10 µM 50 µM 100 µM 150 µM Ab Ab+AgNP Concentration (µM) (a) Zone of inhibition (cm) 1.6 A.flavus Trichoderma Fusarium semitectum 1.4 1.2 1 0.8 0.6 0.4 0.2 0 10 µM 50 µM 100 µM 200 µM Concentration (µM) (b) Fig. 6 Comparative analysis of (a) antibacterial activity and (b) antifungal activity of AgNP for different pathogenic bacteria and fungi. Results are presented in relative units compared with controls(Ab) which is not shown in the graph. Different signs (* and **) letters indicate significant differences (p < 0.05). 11 3.4 Antifungal activity of AgNPs The colloidal AgNPs inhibited the growth of the fungus (A. niger, Trichoderma sp. and F. semitectum) which was seeded in the Muller Hinton agar plate and formed a zone of inhibition around the central cavity. The zone of inhibition with diameter of 1 cm was recorded in case of A. niger, 1.2 cm in Trichoderma sp. and 1.1 cm in case of F. semitectum [Figure 6 (b)]. The antifungal activity is due to the formation of insoluble compounds by inactivation of sulfhydryl groups in the fungal cell wall and disruption of membrane bound enzymes and lipids, which causes cell lysis [1]. We have observed that Trichoderma sp. and F. semitectum are susceptible to the lethal effects of the prepared silver due to the smaller size of AgNPs. 3.5 Cell lines To determine the biomaterial capability of nanoparticles with no toxic effects, the cell viability and cytotoxicity assays were performed. Cell viability was determined by a standard MTT conversion assay. 3.5.1 In vitro cytotoxicity assay Treatment of AgNPs to J774 and THP1 α cell lines exhibited mild cytotoxicity in a dose dependant manner. At low doses (10 µg) no cytotoxic effects were observed whereas at high doses of 100-150 µg of AgNPs mild cytotoxicity was observed. Long-time exposure resulted in additional toxicity to the cells and reached to maximum dead cells after 24 hr of incubation, which might be due to over-accumulation of metal nanoparticles within the cell (Figure 7). Fig.7 Dose-dependent effect of AgNP over cell viability using MTT assay on J774 and THP1 α cells. Results are presented in relative units compared with controls. . Different signs (* and **) letters indicate significant differences (p < 0.05). 12 3.5.2 Intracellular reactive oxygen species estimation The ROS estimation has shown that AgNP exposure to J774 and THP1 α cells caused time dependant increased production of ROS at respective concentration indicating macrophage stimulation. The maximum amount of ROS was produced uptill 4 hr of incubation, which declined at 6 hr (Figure 8). Here, the comparable ROS generation by AgNPs, from nonstimulated cells to mitogen-stimulated cells was observed which indicates the immunomodulatory potential of the synthesized AgNPs. This may be due to the small size of AgNPs as these could easily penetrate through the cell wall in an appreciable number [15]. The maximum free radical activity was obtained by the J774 cells [Figure 8 (a)] and THP1 α cells [Figure 8 (b)] after 4 h of incubation with AgNPs. Free radical generation and analogous encapsulation efficacy capability of AgNPs revealed the potential role of AgNPs as drug / vaccine delivery vehicle for macrophages as well as also indicate towards their immunomodulatory activity. Fig. 8 ROS estimation in (a) J774 cell lines and (b) THP1 α cell lines after incubation with AgNPs at various time points (2 h, 4 h, 6 h). Results are presented in relative units compared with controls. . Different signs (* and **) letters indicate significant differences (p < 0.05). 4. Discussion In the present study, a phosphate solubilizing fungal isolate, FCK 20 was isolated and subjected to its characterization. The sequence of 18S rRNA of the fungal strain FCK 20 was submitted to GenBank with an accession number of (KF934409). The homology search using BLAST 13 indicated a close genetic relatedness of the strain FCK 20 with the rRNA sequence of A. brassicae (18S: 100 % similarity with the reference sequence Ba nkIt1680606 Seq5) in NCBI database. Such a higher identical value confirmed the strain FCK 20 to be A. brassicae. Myconanotechnology has become an extensive field of study involving chemistry, physics, engineering, computing, electronics, energy, agriculture and biomedicine. In the realm of biomedicine, nanotechnology is widely touted as one of the next promising and important approaches to diagnose and treat various ailments [11]. Since physical and chemical methods of metal nanoparticle production are expensive and involve incorporation of toxic chemicals therefore their biological synthesis (bacterial, fungal and plant extract) would be preferred. This owes to their ease of availability, nontoxic nature and quicker synthesis, which prompted us to use this phosphate solubilizing fungus A. brassicae for the synthesis of AgNPs. In best of our knowledge this is the pioneer study showed the use of fungus for the production of nanoparticles. The confirmation of synthesis of AgNPs was based on surface plasmon r esonance involving color alteration. Further, in the UV/VIS absorption, a strong peak located at 370 nm was observed. Average particle size calculated from DLS data was found to be 65.7 nm for AgNPs. Furthermore, the TEM image of the synthesized AgNPs has validated the formation of spherical, nanoparticles, which was 50 nm in diameter. This indicated the reduction of Ag+ to elemental silver (Ag). The UV/VIS spectra of AgNPs was observed at 380 nm and showed their spherical shape. Additionally, the synthesized AgNPs were stable in solution over a time of three months at room temperature. Nano-silver is an effective and a fast-acting microbicide against a broad spectrum of pathogenic bacteria and fungi thus can be utilized in various processes in the medical field [9]. Our findings are in agreement to the previous reports and synthesized AgNPs have showed the considerable antibacterial activities along with the standard antibiotic (tetracycline) against B. cereus. The antibacterial activity of AgNPs is due to the permeability of the cell membrane [23] or formation of free radicals [20] or interaction of AgNPs with the thiol groups of many enzymes thus inactivating them. Beside this, the moderate antifungal activity of AgNPs against Trichoderma sp. and F. semitectum was due to formation of insoluble compounds by inactivation of sulfhydryl groups in the fungal cell wall and disruption of membrane bound enzymes and lipids, causing cell lysis [19]. The MTT assay determines the mitochondrial activity of the cells which, reduce the soluble, yellow MTT into an insoluble, purple formazon. The reduction of MTT to formazon indicates 14 the decrease in mitochondrial metabolism of the cells. Therefore, the absorption of formazon formed, directly co relates to the number of cells whose mitochondrial metabolism is intact even after the exposure of AgNPs. Dose response of AgNPs in J774 cells and THP1 α cells showed the decrease in the reduction of MTT to formazon with the increasing concentration and time of exposure. However, AgNPs were found to be significantly more toxic to THP1 α cells as compared to J774 cells, which could be attributed to the intrinsic anticancer property of AgNPs. This might be due to small particle size of AgNPs with enormous specific surface area, which facilitated further expression and dissolution of ions, leading to increased toxicity. AgNPs are highly reactive, exhibit oxidative potential, contains the ability to bind with biomolecules like proteins and DNA and consequently caused the disturbance in the functioning of bimolecules [2]. In both cell lines J774 and THP1 α a significant increase in the levels of ROS was observed in comparison to the unexposed controls. The maximum amount of ROS was produced after 4 hr of incubation with AgNPs, which declined at 6 h. ROS plays an important role in triggering cellular pathways that can lead to cellular death by either causing nuclear damage or by contributing in cell membrane rupture mechanisms. Exposure of AgNPs to cells caused increased production of ROS, suggested their potential use as an anti- microbicide, occupying its application in agriculture. Moreover, these nanoparticles can also act as immunomodulatory agent alone or in combination with established therapeutic immunomodulatory agents. As these NPs are simply engulfed by the macrophages, they also pose themselve s as targeted drug / vaccine delivery vehicle to macrophages thereby a boom for development of a potent chemotherapeutic vehicle for diseases involving macrophages viz., leishmaniasis, tuberculosis etc. Hence, care has to be taken to utilize this marvel well and in a good, efficient and effective ways. Researchers should also understand its limitations and taking excessive care for its effect on environment and human health. In future, these bio-synthesized nanomaterials (encapsulation) may lead to enhancement of agricultural productivity like slow release of phosphorus from fertilizers and its effective uptake by plants. Fungus A. brassicae contains phosphatase enzyme whose main function is to solubilize the insoluble form of phosphorus in to soluble one. Thus, the bio-nanoparticles prepared from this fungus may display slow release of encapsulated enzyme and hence may improve phosphate solubilization. These synthesized myco-nanoparticles may be mixed with 15 fertilizers to increase the uptake of phosphorus nutrient. However, in future, this strategy needs to be validated. 5. Conclusion The present study showed the mycogenic production of AgNPs with particular emphasis on procedure of synthesis and its potential applications in human welfare as well as in other allied sectors. AgNPs were synthesized from fungus A. brassicae which has phosphate solubilizing ability. Findings showed that synthesized nanoparticles were spherical in shape and has a promising antimicrobial agent against both gram-positive / gram- negative bacteria and pathogenic fungi also. However, higher doses of AgNPs exhibited the cytotoxicity and ROS production in J774 and THP1α cells in time dependant manner. . Observations have also showed the bactericidal activity of synthesized nanoparticles thus implementing their role as antimicrobicidal agent. 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