DESC:DESCRIPTION:
Field of the invention:
The present disclosure generally relates to the technical field of synthesis of silver nanoparticles, and in specific relates to an eco-friendly lagascea mollis mediated silver nanoparticles and method for preparing the same.
Background of the invention:
Metal nanoparticles have recently found important applications in a variety of fields, including electronics, biosensing, plasmonics, optics, and medicine. Silver nitrate-derived nanoparticles are of particular interest due to their wide range of applications. Silver nanoparticles (AgNPs) can be synthesized using a variety of methods, including physicochemical, thermal decomposition, electrochemical, microwave assisted, sonochemical, solvothermal, photosynthesis, photochemical reduction, chemical reduction, and continuous-flow methods. However, these methods can be costly and produce byproducts that pose risks to human health and the environment.
Silver nanoparticles have strong antimicrobial properties, making them effective against a wide range of bacteria, viruses, and fungi. This has led to a growing demand for silver nanoparticles in a variety of applications, such as wound dressings, food packaging, and water purification. Silver nanoparticles have excellent electrical and optical properties, making them useful in a variety of electronic applications, such as touch screens, solar cells, and LEDs. The growing demand for electronic devices is expected to drive the demand for silver nanoparticles in the coming years. Silver nanoparticles are being investigated for a variety of potential pharmaceutical applications, such as tissue engineering, implant technology, nanorobots, and nanomedicine. The success of these applications could lead to a significant increase in the demand for silver nanoparticles in the pharmaceutical industry.
In recent years, green chemistry methods have been developed to prepare AgNPs using plant extracts. These methods are fast, environmentally friendly, and economical. Further, there is some concern that silver nanoparticles may be toxic to humans and the environment. This could limit the growth of the market for silver nanoparticles in some applications. The cost of silver nanoparticles is relatively high, which could limit their use in some applications. However, the cost of silver nanoparticles is expected to decline in the coming years, which could help to drive market growth. There are currently no regulations governing the use of silver nanoparticles in many countries. This could limit the growth of the market until more regulations are in place. The trend towards biological synthesis of silver nanoparticles is an opportunity for the market. Biological synthesis is a more environmentally friendly way to produce silver nanoparticles, and it could help to reduce the cost of silver nanoparticles. The development of new applications for silver nanoparticles is an opportunity for the market. For example, silver nanoparticles are being investigated for use in cancer therapy and wound healing. The success of these applications could lead to significant growth in the market for silver nanoparticles.
Therefore there is a need for silver nanoparticles (AgNps) that are synthesised using medicinal plant at low cost. There is also a need for a method that doesn’t utilises any toxic Chemical for the synthesis of the AgNPs. There is also of a need for eco-friendly AgNPs that are stable for long time. There is also a need for AgNPs are stable for longer periods at low temperature both in the presence and absence of stabilizing agent. There is also a need for AgNPs that doesn’t require pH adjustment for storage, as the colloidal solution pH is sufficient in maintaining the stability at low temperature.
Objectives of the invention:
The primary objective of the invention is to develop silver nanoparticles (AgNps) that are synthesised using medicinal plant at low cost.
The other objective of the invention is to provide a method that doesn’t utilises any toxic chemical for the synthesis of the AgNPs, thereby developing eco-friendly AgNPs that are stable for long time.
Another objective of the invention is to provide AgNPs are stable for longer periods at low temperature both in the presence and absence of stabilizing agent.
The other objective of the invention is to provide AgNPs that doesn’t require pH adjustment for storage, as the colloidal solution pH is sufficient in maintaining the stability at low temperature.
Summary of the invention:
The present disclosure proposes a method for synthesis of lagascea mollis mediated silver nanoparticles (LmAgNps). The following presents a simplified summary in order to provide a basic understanding of some aspects of the claimed subject matter. This summary is not an extensive overview. It is not intended to identify key/critical elements or to delineate the scope of the claimed subject matter. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.
In order to overcome the above deficiencies of the prior art, the present disclosure is to solve the technical problem to provide an eco-friendly lagascea mollis mediated silver nanoparticles and method for preparing the same.
According to an aspect, the invention provides lagascea mollis mediated silver nanoparticles (LmAgNps) for anti-microbial applications and electronics applications. The LmAgNps comprises 5 to 7 weight percentage of lagascea mollis aqueous extract, and 93 to 95 weight percentage of aqueous solution of silver nitrate. The LmAgNps doesn’t require pH adjustment for storage, as the colloidal solution pH is sufficient in maintaining the stability at low temperature.
According to another aspect, the invention provides a method for formulating the LmAgNps. First, at least 2.5 g to 20 g of fresh lagascea mollis leaves are washed to obtain cleaned lagascea mollis leaves. Next, cleaned lagascea mollis leaves are crushed to obtain crushed leaves. Next, the crushed leaves are boiled in at least 50 ml to 100 ml of distilled water for a time period of 15 min to form a first mixture. Next, the first mixture is filtered to obtain a lagascea mollis aqueous extract. In specific, the lagascea mollis aqueous extract comprises a concentration varying from 5% to 30% of lagascea mollis. Next, the lagascea mollis aqueous extract is mixed with an aqueous solution of silver nitrate (AgNO3) to obtain a second mixture. Later, the second mixture is incubated at a temperature of 70°C for a time period of 30 min to form the LmAgNps. In specific, the LmAgNps comprises 0.1 mL of 20% leaf aqueous extract and 0.8ml of 1 mM AgNO3. Later, the LmAgNps are centrifuged for a time period of 15min at speed of 10000 rpm, wherein the LmAgNps are washed twice with double distilled water, dried. Further, the hydrodynamic size of LmAgNps is at least 109.5 nm with zeta potential value of at least -35 mv, indicated negative charge on the surface of the LmAgNPs and had a PDI value of 0.314
According to another aspect, at least 3 ml aliquots of the lagascea mollis aqueous extract and 1 mM AgNO3 are prepared at various ratios of from 1:1 to 1:14.
Further, objects and advantages of the present invention will be apparent from a study of the following portion of the specification, the claims, and the attached drawings.
Detailed description of drawings:
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention, and, together with the description, explain the principles of the invention.
FIG. 1 illustrates a flowchart of a method for formulating lagascea mollis mediated silver nanoparticles (LmAgNps), in accordance to an exemplary embodiment of the invention.
FIG. 2 illustrates a FTIR analysis graph of the LmAgNps, in accordance to an exemplary embodiment of the invention.
FIG. 3 illustrates a XRD pattern of LmAgNps, in accordance to an exemplary embodiment of the invention.
FIG. 4 illustrates a field emission scanning electron microscopy image of LmAgNps, in accordance to an exemplary embodiment of the invention.
FIG. 5 illustrates a high-resolution TEM image of LmAgNps, in accordance to an exemplary embodiment of the invention.
FIG. 6A illustrates a graph depicting a Zeta potential value of LmAgNps, in accordance to an exemplary embodiment of the invention.
FIG. 6B illustrates a graph depicting a Zeta potential value of LmAgNps after 1 year at 4°C, in accordance to an exemplary embodiment of the invention.
FIG. 7A illustrates a graph depicting a Dynamic light scattering analysis of LmAgNps, in accordance to an exemplary embodiment of the invention.
FIG. 7B illustrates a graph depicting a Dynamic light scattering analysis of LmAgNps after 1 year at 4°C, in accordance to an exemplary embodiment of the invention.
FIG. 8 illustrates a standard graph of gallic acid for TPC estimation, in accordance to an exemplary embodiment of the invention.
FIG. 9 illustrates a graph depicting total phenolic content (TPC) of LmAgNPs and LmEt.LE, in accordance to an exemplary embodiment of the invention.
FIG. 10 illustrates a graph depicting total antioxidant capacity assay, in accordance to an exemplary embodiment of the invention.
FIG. 11 illustrates a graph depicting reducing power assay of standard Ascorbic acid, in accordance to an exemplary embodiment of the invention.
FIG. 12 illustrates a graph depicting linear regression plot of % free RSA, in accordance to an exemplary embodiment of the invention.
Detailed invention disclosure:
Various embodiments of the present invention will be described in reference to the accompanying drawings. Wherever possible, same or similar reference numerals are used in the drawings and the description to refer to the same or like parts or steps.
The present disclosure has been made with a view towards solving the problem with the prior art described above, and it is an object of the present invention to provide an eco-friendly lagascea mollis mediated silver nanoparticles and method for preparing the same.
According to an exemplary embodiment of the invention, lagascea mollis mediated silver nanoparticles (LmAgNps) for anti-microbial applications and electronics applications. The LmAgNps comprises 5 to 7 weight percentage of lagascea mollis aqueous extract, and 93 to 95 weight percentage of aqueous solution of silver nitrate. The LmAgNps doesn’t require pH adjustment for storage, as the colloidal solution pH is sufficient in maintaining the stability at low temperature.
According to another exemplary embodiment of the invention, FIG. 1 refers to a flowchart 100 of a method for formulating the LmAgNps. At step 102, at least 2.5 g to 15 g of fresh lagascea mollis leaves are washed to obtain cleaned lagascea mollis leaves. At step 104, cleaned lagascea mollis leaves are crushed to obtain crushed leaves. At step 106, the crushed leaves are boiled in at least 50 ml of distilled water for a time period of 15 min to form a first mixture. At step 108, the first mixture is filtered to obtain a lagascea mollis aqueous extract. In specific, the first mixture is filtered twice using a wattman filter paper. The lagascea mollis aqueous extract comprises a concentration varying from 5% to 30% of lagascea mollis. The lagascea mollis aqueous extract is stored at 4°C.
At step 110, the lagascea mollis aqueous extract is mixed with an aqueous solution of silver nitrate (AgNO3) to obtain a second mixture. In specific, lagascea mollis aqueous extract is mixed with the aqueous solution of AgNO3 a 1:8 ratio. At step 112, the second mixture is incubated at a temperature of 70°C for a time period of 30 min to form the LmAgNps. In specific, the LmAgNps comprises 0.1 mL of 20% leaf aqueous extract and 0.8ml of 1 mM AgNO3. Later, the LmAgNps are centrifuged for a time period of 15 min at speed of 10000 rpm, wherein the LmAgNps are washed twice with double distilled water, dried. Further, the hydrodynamic size of LmAgNps is at least 109.5 nm with zeta potential value of at least -35 mv, indicated negative charge on the surface of the LmAgNPs and had a PDI value of 0.314.
According to another exemplary embodiment of the invention, at least 3 ml aliquots of the lagascea mollis aqueous extract and 1 mM AgNO3 are prepared at various ratios of from 1:1 to 1:14 (extract to salt volume) and studied for optimal conditions for synthesizing LmAgNPs and to know the LmAgNPs stability. Further, effect of physical and chemical parameters such as the reaction time, temperature varies from 40°C to 90°C, metal salt concentration varies from 0.1 mM to 5 mM, concentration of lagascea mollis aqueous extract varies from 5% to 30% and pH is maintained between 6 to 10 in the synthesis of LmAgNPs.
According to another exemplary embodiment of the invention, stability studies are carried out in the presence and absence of a stabilizing agents (PVP) by keeping colloidal solution at room temperature, 4°C and -20°C. In an embodiment, the optimal conditions for the synthesis of LmAgNPs using the lagascea mollis aqueous extract are as follows: 0.1 mL of 20% the lagascea mollis aqueous extract mixed with 0.8 mL of 1 mM AgNO3, and incubation at 70°C in a water bath for 30 min. The appearance of a characteristic surface Plasmon resonance (SPR) peak at 410 nm in UV–Vis spectroscopy confirms the biosynthesis of LmAgNPs. Higher temperatures and alkaline pH favour the rapid synthesis of LmAgNPs, while lower temperatures and acidic pH slow down or suppress the synthesis. The development of LmAgNPs increases over time and remains stable for up to 4 weeks at room temperature or 90 days at 4°C. The SPR peak and color do not completely disappear until 1 year or even longer at 4°C. In the presence of polyvinylpyrrolidone (PVP), the stability is extended to 2 months at room temperature and more than 6 months at 4°C. In pH buffers, 4°C is more favourable for stability than room temperature.
According to another exemplary embodiment of the invention, The Lagascea mollis AgNPs (LmAgNPs) are washed, dried, and characterized using multiple techniques, including UV-VIS spectrophotometry, FTIR, FESEM, EDX, Zeta potential, DLS, HRTEM, SAED, and XRD. FTIR analysis shows that hydroxyl, alkane, and carboxyl groups on the LmAgNPs surface aid in their biosynthesis and stability. Structural characterization reveals that LmAgNPs are predominantly spherical and composed mainly of silver (73%), with oxygen (13.5%), chlorine (6.9%), and carbon (5.09%). They exhibit a hydrodynamic size of 109.5 nm, a zeta potential of -35 mV indicating a negatively charged surface, and a PDI of 0.314, suggesting narrow polydispersity.
Further, the plant Lagascea mollis has been shown to be a promising source for the eco-friendly synthesis of silver nanoparticles (AgNPs). The LmAgNPs are stable for longer periods at 4°C, both in the presence and absence of a stabilizing agent. There is no need to adjust the pH of the colloidal solution for storage, as the natural pH of the solution is sufficient to maintain stability at 4°C. The stability of LmAgNPs at 4°C is attributed to the presence of functional groups on the surface of the nanoparticles. These functional groups, such as hydroxyl, alkane, and carboxyl groups, help to prevent the aggregation of the nanoparticles and protect them from degradation. The stability of LmAgNPs in the absence of a stabilizing agent is further evidence of the eco-friendly nature of this synthesis method. No harsh chemicals or solvents are required, and the only waste product is the leaf extract itself. This makes L. mollis a promising source for the production of AgNPs for a variety of applications. The stability of the LmAgNPs at 4°C makes them well-suited for use in biomedical applications, such as drug delivery and tissue engineering. The eco-friendly nature of the synthesis method makes LmAgNPs a good choice for applications where environmental impact is a concern.
Furthermore, Antioxidant activity of LmAgNPs, LmEt.LE and SNPs are determined by following methods such as TPC-Total Phenolic Content, TAC-Total Antioxidant Capacity, DPPH (2,2-diphenyl-1- picrylhydrazyl) free radical scavenging assay and RPA- reducing power assays. Nanoparticles are hydrophobic and are not soluble in water. Hence LmAgNps - Lagascea mollis AgNPs and SNPs - synthetic AgNPs are sonicated in double-distilled water (dd H2O) for 30min at room temperature for better dispersion, LmEt.LE - Lagascea mollis ethanolic leaf extract & BHT- butylated hydroxytoluene dissolved in ethanol, GA- gallic acid and ASC - ascorbic acid in distilled water and are prepared at required concentrations and used for various assays. Total phenolic contents (TPC) of LmEt.LE and LmAgNps are estimated by Folin Ciocalteu’s method with little modifications. To 0.1ml (ethanol/ dd H2O) of varying concentrations (10-100µg) of LmEt.LE/ LmAgNPs/ GA, 0.5ml of FC reagent and 0.4ml of Na2CO3 is added and made up to 2ml with distilled water incubated in dark for 30mins. And the absorbance is measured at 765nm. Galic acid standard graph (R2=0.997) is plotted with concentrations varying from 0.6-20µg, and the results are expressed in µg of Galic acid equivalents.
The reaction mixture contains 1ml of solvent (ethanol/ dd H2O) with varying concentrations of LmEt.LE/ LmAgNPs/ SNPs/ ASC/ BHT (10-100µg/ml) and 1ml of phosphomolybdenum reagent (1:1:1 of 4mM Ammonium molybdate, 28mM sodium phosphate and 0.6M H2SO4). The reaction mixture is allowed to incubate at 90°C for 90 min in a water bath, cooled under tap water and the absorbance is measured at 695nm at room temperature by spectrophotometer. A standard graph is plotted using ascorbic acid concentration as standard on x-axis against absorbance on y-axis (R2 =0.99). And the results are expressed in terms of Ascorbic Acid equivalents in µg. Butylated Hydroxytoluene is used as reference standard.
To 750µl of ethanol/ dd H2O of varying concentrations of LmEt.LE/ LmAgNPs/ SNPs/ ASC (10-100µg), 750µl of 0.2M phosphate buffer with pH 6.6 and 750µl of 1% potassium. Ferricyanide is added and incubated at 50oC in water bath for 20 mins. Then 1.5ml of 10% TCA is added and the reaction mixture is centrifuged at 3000rpm for 10min. To 1.5ml of supernatant an equal volume of distilled water is added and 0.3ml of 0.1% ferric chloride is added and absorbance is measured at 700nm in spectrophotometer.
In one embodiment, to 1ml of sample (LmAgNPs, LmLE, SNPs and Ascorbic acid) containing varying concentrations of 10 - 100µg, 1ml of 0.1mM ethanolic DPPH is added and incubated in dark for 30 min. The amount of DPPH reduced is measured spectrophotometrically at 517nm14. And the % of Radical scavenging activity (RSA) is measured using the formula. IC50 values are calculated from linear regression plots.
Radical scavenging activity (%)=(Absorbance of control - Absorbance of tes)/(Absorbance of control) ×100%
The catalytic property of bio synthesized LmAgNPs is studied by degradation of methylene blue (MB) using NaBH4 as reducing agent. 3mL of MB (50 µM) is mixed with 1.5 mL (0.005M) of alkaline NaBH4 and 0.5mL of LmAgNPs/SNps (10µg and 20 µg). A control is kept with 0.5ml of water instead of NPs. The degradation of MB dye is measured using a spectrophotometer. The degradation efficiency (%) is calculated using the following Equation.
Degradation efficiency (%)=?A_0-A?_t/A_0 ×100
Where, A0 - absorbance of MB at 0min and at - absorbance of MB at time t. In one embodiment, the change in the color of salt solution from colorless to golden yellow upon addition of plant Lagascea mollis aqueous leaf extract indicates the reduction of salt and formation of nanoparticles. The intensity of color is measured in UV-VIS spectrophotometer. 3ml aliquots of LmAq.LE (L.mollis aqueous leaf extract) and 1mm AgNO3 of different ratios 1:1-1:14 are prepared in duplicates, kept at various temperatures (room temperature, 40-90°C) and observed for development of color (golden yellow) as an indication of AgNPs (silver nanoparticles) formation after the reduction of silver salt by biomolecules from plant extract. The intensity of color formed, and its variation is measured in UV-VIS spectrophotometer at 300- 700nm range. The LmAgNPs synthesis with 1:1-1:14 ratios at 70°C which shows that color development and intensities of SPR peaks are increased with increased volume of salt. Optimum conditions selected for LmAgNps synthesis and further studies is 1:8 ratio (extract to 1mM salt) at 70°C, 30 min of incubation with golden yellow and characteristic peak at 410nm with absorbance maximum of 0.7. Similar results are observed for the Eucalyptus camaldulensis extract which showed maximum absorbance at 410nm with 1mM AgNO3 at temperature 75°C incubated for 60 min.
In one embodiment, a mixture of plant extract and silver salt solution with 1:8 ratio is kept in water bath at 70°C and absorbance is measured at time intervals of 5, 10, 20, 30,40, 50 min, 1hr (60min), 1:30 min and 2 hrs. No color change is observed in the first 5min of reaction and no characteristic SPR peak is obtained from spectroscopic data. After 10 min of incubation the reaction got initiated with the development of pale to light yellow color and gave an absorbance of 0.366 at 396nm ?max. As the reaction proceeded further the color intensified and both absorbance and wavelength increased. At room temperature, the LmAgNPs synthesis is monitored every hour up to 12hrs and at 24hrs, 48hrs, and 120hrs (Day5) and 1week. The color of the colloidal solution (LmAgNPs) turned pale yellow to darker yellow along with gradual increase of both wavelength and Absorbance. At room temperature the rate of reduction is slow, and the synthesis of nanoparticles initiated only after 5hrs, and their size increased by 24hrs with 430nm wavelength absorbance of 0.7. While Cuphea procumbent took 6hrs for synthesis of AgNPs at room temperature with strong SPR peak in the range from 350 to 450 nm. Hence temperature is applied as an external energy source to speed up the reaction and synthesis of smaller sized nanoparticles.
In one embodiment, At 40°C, the color change is not observed. As the temperature increased from 50 -90°C the reduction of salt became faster, size / wavelength is reduced (416 - 410nm), and the SPR peak intensities increased. Similarly, Kappa-carrageenan polymer mediated AgNPs also showed increased absorption intensities with increased temperatures from 25-80°C and the SPR peak became sharp and narrow with ?max 416 – 410 from 50-70°C which indicates a greater number of AgNPs formation with smaller size. Effect of AgNO3 salt concentration: 0.1mM – 0.5mM of AgNO3 salt showed no characteristic color or SPR peak. With 1mM-5mM of salt concentrations golden yellow to dark orange yellow shade is observed. The color and absorption intensities increased with increasing concentrations of salt along with increased ?max from 410- 420nm. These results are correlated with Cissus quadrangulaus where the absorbance maximum at 410nm shifted to 450nm with increased salt concentration.
In one embodiment, Effect of Lagascea moliis Aqueous leaf Extract concentration: With1% (LMAq.LE) leaf extract no significant SPR peak and color is formed. As LMAq.LE concentrations increased from 5-30%, the color and absorbance are increased with ?max from 405 - 427nm. Similar observations are reported with varying concentrations of Lysimachia foenum-graceum dry leaves extract from 0.003wt% – 1wt% the absorption maxima increased from 410-430, And increased A. heterophyllus seed powder extract from 2% - 10% the absorption maxima increased from 410 to 420nm, indicating that there is a change in the size of nanoparticle.
In one embodiment, LmAgNps are synthesized in different pH 6-10 buffers. At acidic pH6 (acetate buffer) no color change is observed, not forming any AgNPs. Similar results are reported with citrus Limon extract. From pH7-10 (pH7-9 tris -HCl buffer, pH10 glycine-NaOH buffer) color changes from light yellow to darker shades observed. At lower pH the synthesis of AgNPs is suppressed, whereas neutral and alkaline pH facilitated the synthesis. The intensity of SPR peak and ? max (407nm-415nm) increased with increasing pH indicating the effect of pH on size and number of nanopartarticles. Similarly lemon peel extract also showed SPR peaks shift from 405 – 425nm as the pH changed from pH 6-10, where pH6 showed no significant peak. These findings are also correlated with H.thabacia extract where the synthesis is diminished at acidic pH and facilitated by neutral and basic pH.
In one embodiment, The synthesized LmAgNps colloidal solution at 70°C are stored at room temperature, 4°C & - 20°C to check their stability in buffers as well as with stabilizing agent. The LmAgNps which are synthesized with 1:8 (0.1ml of extract and 0.8ml of salt) ratio of 20% LmAqLE to 1mM AgNo3 and absorbance of 0.7 with SPR peak at 410nm kept at room temperature attained equilibrium by 24hrs then increase in the absorbance is observed up to 31days with no change in the ? max at 415nm. There, after the gradual decrease in both wavelength and absorbance is observed when monitored for 1yr 3months where the minute color and peak are still appeared indicated the presence of dispersed nanoparticles. Time dependent stability studies conducted with ligustrum vulgare berries showed 2 weeks of stability with appearance of peak at same region in UV spectrum analysis. These results are correlated with Cassia roxburghii AgNPs which are stable for 2months and increased in the absorbance for 12months with little change in the ? max at 6months and 12months stored at room temperature.
In one embodiment, At 4°C, Lagascea mollis AgNPs showed a stable increase in absorbance, reaching equilibrium at a ?max of 415 nm in 9 days and maintaining this peak until 116 days, with gradual absorbance decline afterward. The colloidal color and SPR peak remained stable for over two years, confirming nanoparticle stability, whereas storage at -20°C led to rapid intensity reduction. pH studies revealed optimal stability at pH 8, with nanoparticles maintaining the SPR peak for up to 660 days at 4°C. Compared to Azadirachta indica AgNPs, which remained stable only for 5 days at 25°C, Lagascea mollis AgNPs demonstrated superior stability.
To the synthesized LmAgNps, 0.5%-5% PVP solutions are added separately and the changes in SPR peak are monitored periodically overtime at room temperature and at 4°C using UV-VIS spectrophotometer. With 3%PVP the LmAgNps are stable for 276days at room temperature and 1.10yrs at 4°C. At room temperature, with 0.5%PVP LmAgNPs are stable for 142days, and with 1, 2,4and 5% for 180days. At 4°C, with 0.5% &1% PVP, the LmAgNPs are stable for 1.6yrs (540days), and with 2-5%PVP, stable for 1.10yrs (660days). Increased PVP concentrations from 0.5% -5%, prolonged their stability, at 4°C, AgNPs showed better stability than at room temperature in all the 6 varying concentrations of PVP (0.5-5%). The literature data revealed that the use of 0.2-0.5%PVP, where increasing PVP concentration prevents agglomeration. And with 0.5%PVP, the Ruellia Tuberosa-AgNPs are stable for 45 days at room temperature and for 6months at 4°C. In a similar study of Eucalyptus camaldulensis AgNPs remained stable for 5months with 5 mg/mL PVP with highest intensity of SPR peak at 430nm which indicates smaller size and high yield of AgNPs. A low concentration of PVP is insufficient in coating the AgNPs lead to aggregation and growth of particle size.
In one embodiment, to the synthesized LmAgNPs in various buffers (pH 7-10) different concentrations of PVP are added and stability is studied as mentioned above. At room temperature in pH7, 3%PVP showed good stability for 1.6yrs, in pH8 with 1, 3, and 4% PVP for 1.6yrs and with 5%pvp for 1.10yrs and in pH9 with 1, and 2% PVP for 1.6yrs, while with pH- 10 for 10months (data not included). At 4°C, all the four buffers used with varying PVP concentrations showed better stability for 1.10yrs than at room temperature. However, this study is carried out for 1.10yrs and continued till the loss of color as well as SPR peak.
According to another exemplary embodiment of the invention, FIG. 2 refers to a FTIR analysis graph 200 of the LmAgNps. The completely dried pellet is ground into fine powder and used for characterization of NPs to determine the shape, size and the presence of functional groups. The FTIR analysis graph 200 exhibits the major functional groups present in the biomolecules which act as reducing and capping of LmAgNps. The peak at 3783 from plant extract shifted to 3785 in AgNPs represents the presence of OH groups of alcohols, and peaks at 3519 – 3514 represents NH bond amines, peaks at 2922 shifted to 3002 and 2857 to 2837 represents CH stretching vibrations peak at 1739 shifted to 1783, 1762, 1728 & 1708, represents C=O, carbonyl and carboxylic acids, 1655 &1632 to 1664,1605 represents C=C of aromatic compounds, peaks at 1465 and 1382 shifted to 1498, 1447, 1408, 1328 represents C-H bend of esters. The peaks at 1261 represent aromatic ester, C-O. 1165, 1112, 1036, 985, 903, from plant extract represents C-N, C-O, C=C, CH, which are missing in LmAgNps indicate their active involvement in reduction and synthesis of nanoparticles. The peaks appeared from 500 and below represents alkyl halides.
According to another exemplary embodiment of the invention, FIG. 3 refers to a XRD pattern 300 of LmAgNps. The XRD pattern 300 of LmAgNps depicted the presence of distinct diffractive peaks with 2? values at 38.2, 44.2, 64.6, 77.3, and 81.7 and indexed with 111, 200, 220, 311, 222 planes of face centered cubic silver, correlated with the JCPD file no.04-0783 of standard diffraction patterns of silver. The (111) plane peak intensity is relatively higher, indicating the synthesized AgNPs are crystalline, this data is also correlated with (amcsd 0011135) crystallography database of silver, other peaks at 27.8, 32.3, 46.3, 54.9, 57.5, 67.5 and 85.7 may be due to the organic compounds of plant extract which involved in silver nanoparticles synthesis. Similar 2? peaks are observed with Nanoparticles synthesised from Scoparia dulcis, and Salvedora persicaI. The average crystalline size of the LmAgNps is calculated using Scherr equation is 13.26nm. Whereas Carduus crispus whole plant and flower gave average crystallite size AgNPs-W 13nm and AgNPs-F 14nm respectively and face centered cubic.
Table 1:
Crystallite size by Scherr equation
Peak no. 2? ? FWHM D= K?/ßCos?
1 27.89918 13.94959 0.49118 16.66538
2 32.32565 16.16283 0.49308 16.77459
3 38.23305 19.11653 1.18753 7.0802
4 44.26791 22.13396 1.17127 7.322237
5 46.32228 23.16114 0.54212 15.93874
6 54.90753 27.45377 0.57447 15.58391
7 57.56584 28.78292 0.58456 15.50596
8 64.6056 32.3028 0.96216 9.768545
9 67.52568 33.76284 0.4932 19.3754
10 77.38659 38.6933 1.47508 6.900246
11 81.54911 40.77456 1.12646 9.31279
12 85.77201 42.88601 0.57145 18.9734
Average crystallite size 13.26nm

According to another exemplary embodiment of the invention, FIG. 4 refers to a field emission scanning electron microscopy image 400 of LmAgNps. FESEM analysis revealed that LmAgNps are spherical in shape from the images obtained at 100nm with 5kv are in between 27nm-60nm. EDS spectrum analysis with highest peak at 3keV confirming silver as major element contributing 73% and the other elements, chlorine 6.9%, carbon 5.09%, oxygen 13.5%, very trace amounts of Al and Si also reported. The results are correlated with Achillea millefolium, Artemisia campestris synthesized AgNPs which are in between 50-80nm and 63-68nm with spherical in shape and their EDS spectrum revealed that the synthesized AgNPs mostly comprises of silver.
According to another exemplary embodiment of the invention, FIG. 5 refers to a high-resolution TEM image 500 of LmAgNps. The High-resolution TEM image 500 confirmed the obtained LmAgNps are spherical in shape. The high-resolution TEM image 500 is analysed with ImageJ software and size distribution histogram of the same revealed that the LmAgNps are in the range of 5-45nm, and average size is 20.3nm. Artemisia Sieberi Besser (Dermanah), a plant from the Asteraceae family, also gave an average size of 20nm. These results agreed with UV – VIS spectrum. The bright circular rings in SAED pattern of the LmAgNps indexed with muller indices and correlated with standard silver diffraction planes. The planes at 111, 200, 220, and 311 confirmed that synthesized AgNPs are face-centered cubic silver structure.
According to another exemplary embodiment of the invention, FIG. 6A refers to a graph 600 depicting a Zeta potential value of LmAgNps. FIG. 6B refers to a graph 602 depicting a Zeta potential value of LmAgNps after 1 year at 4°C. The Zeta potential value of LmAgNps at 24.8°C is -35mv (as shown in FIG. 6A) which is correlated with the results of Angelica cigas (-35±0.79mv). The Zeta potential values below -30 and above +30 are considered to be stable. The negative charge of the nanoparticles is presented by surface bound reducing agents from plant extract, phytochemicals like amino acids, flavonoids, etc. may involve in capping of LmAgNPs.
Stability of LmAgNps over time is studied by Zeta potential analysis at room temperature and at 4°C. Where the LmAgNps stored at room temperature and at 4°C for 6 months and 1 year are separated by centrifugation and analysed by Zeta. After 6 months of storage, the Zeta potential value became more negative i.e. -73.9mv at room temperature and -75.2mv at 4°C and after 1year it increased to -100.6mv and -132.2mv respectively. The increase in the negative Zeta value is an indication of increased repulsion1. While D. stramonium mediated AgNPs gave a zeta potential value of 15.2 mV which is reduced after two months to 0.740 mv. While increasing pH from 6-10 the zeta potential value of Z. tenuior mediated AgNPs changed from -22.3 to -65.0mV.
According to another exemplary embodiment of the invention, FIG. 7A refers to a graph 700 depicting a Dynamic light scattering analysis of LmAgNps. FIG. 7B refers to a graph 702 depicting a Dynamic light scattering analysis of LmAgNps after 1 year at 4°C. The DLS analysis revealed that the LmAgNps are polydisperesed with Z-Average size 109.5nm and 0.314 PDI, as shown in FIG. 7A. Silver nanoparticles from Angelica cigas also showed similar results where the particle size is 102.3 ± 1.25 and PDI 0.314 ±0.1.
Stability of LmAgNps over time is studied by DLS analysis at room temperature and at 4°C. Where the LmAgNps stored at room temperature and at 4°C for 6 months and 1 year are separated by centrifugation and analysed by DLS. Referring to FIG. 7B, the DLS report revealed that the hydrodynamic size of LmAgNPs stored at room temperature reduced to 64.3nm by 6 months and rose to 391.6nm by 1 year while PDI is 0.299 and 0.196 respectively. The LmAgNPs stored at 4°C are slightly varied by 6months (92.3nm) and PDI remained similar (0.201, 0.208) the PDI value below 0.5 indicates monodispersed nanoparticles. The hydrodynamic sizes of NPs synthesized from Dittany ranged between (81-79nm), Sage (110-115nm), Sea Buckthorn (130-137nm) and Calendula (285-336nm) during the storage time of 120 day.
In one embodiment, by scavenging the free radicals generated, an antioxidant ceases oxidation. The antioxidant itself gets oxidized to neutralize the free radicals. The effectiveness of plant extract as a reducing agent in the formation of nanoparticles can be determined by its capacity to neutralize free radicals. In the present study the Antioxidant activity of LmAgNPs, Lagascea mollis Ethanolic leaf extract (LmEt.LE), Synthetic AgNPs (SNPs) and standard Ascorbic acid (ASC)/ butylated hydroxytoluene (BHT) / Gallic acid (GA)is tested using following methods namely, Total phenolic content, Total Antioxidant capacity, Reducing power assay, and DPPH free radical scavenging assay.
According to another exemplary embodiment of the invention, FIG. 8 refers to a standard graph 800 of gallic acid for TPC estimation. A 100µg of ethanolic extract gave 1.7µg GAE and LmAgNPs gave 9.75µg GAE which is 5.73 folds higher than LmEt.LE. From (y=mx+c) exponential equation the TPC is measured for 1mg of dry ethanolic leaf extract and LmAgNPs which are found to be 19.19µg and 96.47µg of GAE/mg respectively. The TPC content of LmAgNPs showed more than that of Rubus fruticosus AgNPs which gave 7.37g GAE/100g, while its extract gave 3.49 g GAE/100g. While AgNPs synthesized from unripe pawpaw peels and unripe banana peels extract are found to 85.30 ±0.57mg GAE/g and 70.64 ±0.27mg GAE/g respectively. Whereas N. nimmoniana AgNPs gave 89.09 ± 4.97 mg GAE/g and its fruit extract gave 194.56 ± 3.15 mg GAE/g.
According to another exemplary embodiment of the invention, FIG. 9 refers to a graph 900 depicting total phenolic content (TPC) of LmAgNPs and LmEt.LE. The total phenolic content (TPC) is increased with increasing concentrations of LmAgNPs and LmEt.LE from 10-100µg. The TPC of LmAgNPs, measured in GAE (gallic acid equivalents) is significantly higher than the ethanolic leaf extract of Lagascea mollis.
Table-2:
Total phenolic content in µg of GAE
Concentration/mL LmEt.LE LmAgNps p- values
mean SD mean SD
10µg 0.02 ±0.075 0.72 ±0.126 0.003
20µg 0.28 ±0.133 1.62 ±0.082 0.0002
30µg 0.46 ±0.062 2.7 ±0.327 0.002
40µg 0.62 ±0.084 3.19 ±0.102 0.0007
50µg 0.76 ±0.102 4.2 ±0.19 0.001
60µg 0.91 ±0.059 5.3 ±0.055 0.00004
70µg 1.12 ±0.035 6.07 ±0.103 0.0001
80µg 1.42 ±0.04 7.04 ±0.4 0.0009
90µg 1.64 ±0.129 8.37 ±0.227 0.0001
100µg 1.78 ±0.067 9.75 ±0.385 0.0002
The TPC content of LmAgNPs and LmEt.LE are statistically significant
with p-value = 0.001 (T test performed in Microsoft excel)

According to another exemplary embodiment of the invention, FIG. 10 refers to a graph 1000 depicting total antioxidant capacity assay. TAC is measured using phosphomolybdenum assay where the Mo (VI) is reduced to Mo (V) by the electrons donated by an antioxidant from sample/standards to form green phosphate or Mo (V) compounds. The reduction of molybdenum is increased with increasing concentrations from 10- 100µg which implies that total antioxidant capacity is dose dependent. The LmAgNPs showed the highest antioxidant capacity in terms of ascorbic acid equivalents followed by SNPs and LmEt.LE. At 100µg/ml LmAgNPs, SNPs and LmEt.LE gave 22.89±1.4, 12.07±0.93and 7.59±0.59µg AAE (Table-3) respectively while the standard BHT gave 34.02±0.82µg of AAE at the same concentration. The reference standard BHT has the highest activity than the samples. LmAgNps displayed the highest antioxidant capacity compared to the extract and SNPs.
Table 3:
Total Antioxidant capacity in µg of AAE
Concentration/mL BHT LmAgNPs LmEt.LE SNPs
Mean SD Mean SD Mean SD Mean SD
10 µg 5.52 ±0.1 0 0 0 0 0 0
20µg 8.1 ±0.5 1.2 ±0.18 0.09 ±0.04 0.21 ±0.43
30µg 11.57 ±1.05 2.31 ±0.53 0.55 ±0.18 1.07 ±0.21
40µg 18.07 ±1.12 3.46 ±0.36 1.24 ±0.27 1.69 ±0.22
50µg 21.71 ±0.79 4.29 ±0.21 1.79 ±0.1 2.74 ±0.25
60µg 24.81 ±0.25 5.86 ±0.47 2.19 ±0.18 3.83 ±0.29
70µg 27.17 ±0.33 7.17 ±0.29 2.64 ±0.29 5.6 ±0.64
80µg 29.31 ±0.22 10.79 ±0.32 3.31 ±0.25 8.36 ±0.22
90µg 31.67 ±0.57 14.31 ±1 4.29 ±0.22 9.9 ±0.28
100µg 34.02 ±0.82 22.89 ±1.4 7.59 ±0.59 12.07 ±0.93
The TAC of the samples in terms of AAE are statistically significant with the p-value < 0.001 (f=
50.45)

The order of total antioxidant capacity of experimental substrates is as follows standard BHT > LmAgNps > SNPs > LmEt.LE. LmAgNps showed 2.8 folds higher TAC than LmEt.LE and 1.7 folds than SNPs at 100µg/mL. In a similar study Callisia repens’s AgNPs gave 24.543 ± 0.32 AAE /1g, and leaf extract gave 19.777 ± 0.23 AAE/ 1g. At 1mg/ml A. acuminata AgNPs gave 190.98±1.51 µg AAE/mL while its leaf extract has 106.37±0.68 µg AAE/mL at same concentration. Similarly, D. trifoliata AgNPs showed highest antioxidant capacity than its extract with 1328.9 mg and 114.4 mg of Trolox equivalents at 1g. Compared to the above findings LmAgNps showed good antioxidant capacity in terms of Ascorbic acid Equivalents at µg/mL.
According to another exemplary embodiment of the invention, FIG. 11 refers to a graph 1100 depicting reducing power assay of standard Ascorbic acid. The antioxidants that are present in the reaction mixture cause the reduction of Fe3+/ferricyanide complex to ferrous form. The mean absorbance and standard deviations, with respect to their concentration, are depicted in the table below (Table-4). Absorbance is directly proportional to potential reduction, which in turn is directly proportional to the antioxidant capacity of samples.
Increase in the absorbance with increasing concentrations of samples indicates that antioxidant capacity of samples is dose dependent which is correlated with mediated AgNPs, the mediated AgNPs also showed dose dependent reducing potential. Among the 3 tested samples, LmAgNPs, has the highest reduction capacity than ethanolic leaf extract (LmLE) and SNPs with absorbance of 0.193, 0.089 and 0.046 respectively. Ascorbic acid µM is used as standard and 10 µg/ml of ASC gave an absorbance of 0.339±0.0055. LmAgNPs have 2-folds and 4-folds higher reduction potential than LmEt.LE and SNPs. The order for reduction potential is LmAgNPs > LmEt.LE > SNPs.
These results are correlated with the reports of E. purpurea AgNPs which also showed similar type of reduction ability where AgNPs synthesized has highest reducing potential than the extract. The reduction of Fe3+/ferricyanide complex increased when concentration increased from 25–100 µg/mL where absorbance increased from 0.054 to 0.063 with AC-AgNPs and from 0.196 to 0.328 with BHT. Methanolic extract of Costus pictus - MECP, and its silver nanoparticles – MECPAgNPs gave an absorbance of 0.7 and 0.8 with 100 µg/mL respectively.
Table 4:
Ferrous reducing power assay (a.u at 700nm)
Concentration
/mL LmAgNps LmEt.LE SNPs
Mean SD Mean SD Mean SD
10 µg 5.52 ±0.1 0 0 0 0
20µg 8.1 ±0.5 1.2 ±0.18 0.09 ±0.04
30µg 11.57 ±1.05 2.31 ±0.53 0.55 ±0.18
40µg 18.07 ±1.12 3.46 ±0.36 1.24 ±0.27
50µg 21.71 ±0.79 4.29 ±0.21 1.79 ±0.1
60µg 24.81 ±0.25 5.86 ±0.47 2.19 ±0.18
70µg 27.17 ±0.33 7.17 ±0.29 2.64 ±0.29
80µg 29.31 ±0.22 10.79 ±0.32 3.31 ±0.25
90µg 31.67 ±0.57 14.31 ±1 4.29 ±0.22
100µg 34.02 ±0.82 22.89 ±1.4 7.59 ±0.59
The reducing potential of the samples is statistically significant with the p-value < 0.001 (f =16.36)

According to another exemplary embodiment of the invention, FIG. 12 refers to a graph 1200 depicting linear regression plot of % free RSA. DPPH (2,2-diphenyl-1-picrylhydrazyl) is a purple and free stable radical, reacts with hydrogen donor, and produces reduced form of DPPH (hydrazine form), that leads to the color change from purple to pale yellow. The amount of color disappeared depends on the concentration of the antioxidant and is measured spectroscopically. The % radical scavenging activity increased with increasing concentration of samples from 10-100 µg/mL (Table-2) and showed dose dependent response.
Lemon zest and its AgNPs, GE-AgNPs also showed dose dependent response with DPPH. With increasing concentration from 10-100 µg/ml the biosynthesized LmAgNps demonstrated a good radical scavenging activity of 13.5 - 55.5% whereas LmEt.LE and SNPs showed 7.2-15% and 1.79-8.4% respectively at the same concentration where standard Ascorbic acid showed 48.02 - 96.9% of RSA. Polyalthia longifolia mediated AgNPs also showed similar type of activity with increasing concentration from 10-100µg/ml where the % of RSA increased from 23% to 82% and with ascorbic acid from 31% to 91%. Synthetic AgNPs SNPs and ethanolic leaf extract (LmEt.LE) had lower levels of radical scavenging activity than LmAgNPs. D. stramonium AgNPs showed good antioxidant activity than chemical /synthetic AgNPs.
The IC50 values, where the inhibition of DPPH free radicals is 50%, are calculated from equation of intercept from linear regression plots with R2- 0.9, which are plotted with concentration against % RSA. Ascorbic acid has the lowest IC50 value of 10.66 µg/ml, while LmAgNps, LmEt.LE and SNPs gave 89.7µg/ml, 494.33µg/mL and 598.5 µg/mL respectively. This showed that the LmAgNps has the highest RSA than leaf extract by 5.5 folds and SNPs by 6.6 folds. These findings are correlated with Flemingia wightiana leaf extract AgNPs which gave an IC50 value of 71.9µg/ml, and D. trifoliata seed extract which gave the IC50 value of 332.44 µg/mL where its biosynthesized AgNPs gave 8.25 µg/mL. GE-AgNPs gave an IC50 value of 30.71 ± 0.22 µg/mL and ascorbic acid gave 10.33 ± 0.16 µg/mL53. The order of DPPH free radical scavenging activity is LmAgNPs > LmLE > SNPs.
Table 5:
DPPH free radical scavenging assay (% of RSA)
Concentration
/mL Ascorbic acid (std) LmAgNPs LmEt.LE SNPs
%Mean SD %Mean SD %Mean SD %Mean SD
10µg 48.02 ±0.102 13.54 ±0.89 7.25 ±0.349 NA NA
20µg 67.522 ±0.091 17.95 ±0.37 8.28 ±0.374 1.79 ±1.33
30µg 87.909 ±1.255 22.97 ±1.1 8.77 ±0.539 2.16 ±0.15
40µg 95.456 ±0.301 27.84 ±0.54 9.19 ±0.571 2.63 ±1.25
50µg 96.042 ±0.189 32.22 ±1.04 10.04 ±0.717 3.86 ±0.63
60µg 96.335 ±0.308 37.16 ±0.84 10.76 ±0.535 4.89 ±1.85
70µg 96.554 ±0.132 41.21 ±0.92 12.94 ±0.669 5.18 ±0.39
80µg 96.481 ±0.192 44.68 ±0.05 13.42 ±0.815 6.12 ±1.03
90µg 96.555 ±0.31 49.17 ±1.31 14.21 ±0.73 6.79 ±0.55
100µg 96.92 ±0.235 55.5 ±0.59 15 ±0.729 8.4 ±1.2
The RSA (%) of the samples are statistically significant with the p-value = 0.001(f = 213.57)

In one embodiment, the bio synthesised LmAgNps had degraded Methylene Blue (MB) using NaBH4 at a concentration of 10µg by 54.48% ±1.67 and at 20µg by 66.76% ±2.4 within 80min and the chemically synthesised AgNPs (SNPs) degraded MB by 65.57% ±0.81, 64.4±0.32 at 10 and 20µg respectively. While the Control without AgNPs degraded MB by 64.88% ±0.56 by 80min. From the above results the degradation efficacy of LmAgNps with a concentration of 20µg is found to be significant than control and SNPs at 80min.
Table 6:
Degradation efficacy of LmAgNPs and SNPs
Control LmAgNps
10µg LmAgNps
20µg SNPs 10µg SNPs 20µg
Time mean SD mean SD mean SD mean SD mean SD
20min 25.13 ±0.88 20.88 ±0.12 21.44 ±0.97 19.2 ±0.36 18.82 ±0.2
40min 42.78 ±1.06 40.07 ±0.1 41.04 ±1.38 39.73 ±0.24 39.35 ±0.58
60min 56.95 ±1.86 55.4 ±1.42 56.45 ±2.49 54.17 ±1.17 52.95 ±1.79
80min 64.88 ±0.56 64.48 ±1.67 66.76 ±2.48 65.57 ±0.81 64.4 ±0.32
100min 74.52 ±0.57 73.72 ±0.52 73.73 ±0.5 73.82 ±0.92 73.51 ±1.33
The DE (%) is statistically significant with p-value <0.05 (i.e. p= 0.007 and f =5.14)

All the experiments are done in triplicates and the mean ±SD is reported. The linear regression plots are used to determine GAE, AAE and IC50 values. One way ANOVA is applied to determine the statistical significance between samples by web application and p-value are <0.001. The pairwise correlation between each sample is tested by Bonferroni Post-hoc test and p-values are tabulated in table 7.
Table 7:
Table-8: Bonferroni Post-hoc-Tests
DPPH RPA TAC
ASC - SNPs <.001 NA NA
ASC - LmAgNPs <.001 NA NA
ASC – LmEt.LE <.001 NA NA
SNPs - LmAgNPs <.001 <.001 0.134
SNPs - LmEt.LE <.001 0.002 0.068
LmAgNPs - LmEt.LE 0.001 <.001 0.062
BHT - SNPs NA NA <.001
BHT - LmAgNPs NA NA <.001
BHT - LmEt.LE NA NA <.001

In one embodiment, biogenic silver nanoparticles (AgNps) and their application has been gaining more importance for the last two decades for being less toxic and eco-friendly compared to chemically synthesized nanoparticles. Microorganisms and plants are employed in synthesis of biogenic AgNPs. The Lagascea mollis leaf aqueous extract has potential for synthesis of AgNPs, with a SPR peak at 410nm. Higher temperatures, neutral and alkaline pH favoured rapid synthesis, while at lower temperatures and acidic pH delayed and suppressed the synthesis. The development of AgNPs increased over time and remained stable up to 4 weeks at room temperature, 116 days at 4oC, SPR peak and color is retained till 2 years at 4oC. While the zeta potential values also increased from -35 to -75 and to -135 for 6months and 1 year of storage at 4oC. And with stabilizing agent 3%pvp showed good stability at room temperature. The LmAgNPs are stable for longer periods at 4oC both with and without the presence of stabilizing agent (PVP) and buffered (pH 7-9) solutions. The synthesized LmAgNPs exhibited an average size of 20.3nm and FCC crystalline nature with -35mv zeta potential value and 0.314 PDI. The LmAgNps gave IC50 value of 89.7µg/ml with DPPH Assay, and highest AAE & GAE in TAC assay and TPC assay respectively. In reduction potential assay also the LmAgNPs showed better antioxidant activity than the ethanolic leaf extract and commercial or synthetic AgNPs. Thus, the synthesized biogenic AgNPs can be used for potential biological applications such as drug development (antibacterial, antidiabetic, anticancer), catalysis, diagnostics etc.
Numerous advantages of the present disclosure may be apparent from the discussion above. In accordance with the present disclosure, an eco-friendly lagascea mollis mediated silver nanoparticles and method for preparing the same is disclosed. The proposed LmAgNPs are synthesised using medicinal plant at low cost. The proposed method doesn’t utilises any toxic Chemical for the synthesis of the LmAgNPs. The proposed eco-friendly LmAgNPs are stable for long time. The proposed LmAgNPs are stable for longer periods at low temperature both in the presence and absence of stabilizing agent. The proposed LmAgNPs doesn’t require pH adjustment for storage, as the colloidal solution pH is sufficient in maintaining the stability at low temperature.
It will readily be apparent that numerous modifications and alterations can be made to the processes described in the foregoing examples without departing from the principles underlying the invention, and all such modifications and alterations are intended to be embraced by this application.
,CLAIMS:CLAIMS:
I / We Claim:
1. A method for synthesizing Lagascea mollis-silver nanoparticles (LmAgNPs), comprising:
washing fresh Lagascea mollis leaves with water to obtain cleaned leaves, and crushing the cleaned leaves to obtain a crushed leaf mixture;
boiling the crushed leaves in distilled water for a time period of 15 minutes to form a first mixture;
filtering the first mixture to obtain a Lagascea mollis aqueous extract, which is then stored at 4°C;
mixing the Lagascea mollis aqueous extract with an aqueous solution of silver nitrate (AgNO3) to form a second mixture;
incubating the second mixture to form Lagascea mollis-silver nanoparticles (LmAgNPs); and
centrifuging the LmAgNPs for 15 minutes at a speed of 10000 rpm, followed by washing twice with double distilled water, and drying to obtain purified LmAgNPs.
2. The method for synthesizing Lagascea mollis-silver nanoparticles (LmAgNPs) as claimed in claim 1, wherein at least 2.5 g to 20 g of the fresh Lagascea mollis leaves is washed for synthesizing LmAgNPs.
3. The method for synthesizing Lagascea mollis-silver nanoparticles (LmAgNPs) as claimed in claim 1, wherein the crushed leaves are boiled in at least 100 ml of distilled water for at least 15 minutes to form the first mixture.
4. The method for synthesizing Lagascea mollis-silver nanoparticles (LmAgNPs) as claimed in claim 1, wherein the obtained Lagascea mollis aqueous extract 5% to 30% of Lagascea mollis.
5. The method for synthesizing Lagascea mollis-silver nanoparticles (LmAgNPs) as claimed in claim 1, wherein the Lagascea mollis aqueous extract is mixed with the AgNO3 at a ratio of 1:8.
6. The method for synthesizing Lagascea mollis-silver nanoparticles (LmAgNPs) as claimed in claim 1, wherein the second mixture is incubated at a temperature of at least 70°C for a time period of 30 minutes to form the LmAgNPs.
7. The method for synthesizing Lagascea mollis-silver nanoparticles (LmAgNPs) as claimed in claim 1, wherein the LmAgNPs comprise 0.1 ml of 20% leaf aqueous extract and 0.8 ml of 1 mM AgNO3.