Preliminary Investigation Into Prospective Applications of Nanosilver, Produced Using Teff (Eragrostis tef) Flour Extract

Silver-based nanomaterials have etched an indelible mark in multiple domains. The green synthesis of silver nanoparticles has received signi�cant attention over the last few years vis-à-vis the conventional use of toxic chemicals and reagents in the preparatory stages. In this milieu, the work reported here highlights the use of an aqueous extract of teff (Eragrostis tef) �our to prepare silver nanoparticles (TSNPs). The compositional abundance of various phytochemicals, sunlight-induced bio-reduction of silver ions, and subsequent stabilization of the nanostructures by teff’s biomolecules were adroitly exploited. UV-visible spectroscopic analysis was employed to track the evolution of the TSNPs over time and their month-long storage stability. Exhibiting λ max at around 426 nm and energy gap (as revealed by Tauc’s plot) of 2.26 eV, the silver nanomaterial was employed for methylene blue dye degradation (50% degradation in less than 50 min) and DPPH scavenging (IC 50 = 243.42 µL containing 410 µg of TSNPs), attesting their catalytic and anti-oxidant potency. On the other hand, anticoagulant action and a concentration-dependent variation were noted for radicle length post germination of Cicer arientinum seeds, treated with the TSNPs. The TSNPs could have profound implications in multiple domains.


INTRODUCTION
In the quest for sustainable and eco-friendly approach for the fabrication of nanoparticles and other nanoscale structures, green synthesis harnesses the power of biological and renewable entities, such as plants, microorganisms, or enzymes, to produce nanomaterials (Konwarh et al., 2010;Konwarh et al., 2011, Bachheti et al., 2019;Alsaiari et al., 2023;Dogra et al., 2023).Unlike the conventional slow and costly methods that entail toxic chemicals and energy-intensive processes, resulting in polydisperse, unstable nanoparticles with requisite for additional capping agent (Kaabipour and Hemmati, 2021) Teff (Eragrostis tef), the annual cereal grass (family Poaceae), grown for its tiny nutritious seeds is native to Ethiopia and Eritrea and serves as a staple food crop to millions of people.The recognition that teff is gluten-free has instigated tremendous research impetus in the food science domain (Homem et al., 2022;Girija et al., 2022).Consequently, scientific documentation on the nutritional composition, processing quality, and health benefits of teff is pacing up.The existing literature suggests that teff is composed of complex carbohydrates with slowly digestible starch.Teff has a similar protein content to other more common cereals like wheat, but is relatively richer than the latter in the essential amino acid, lysine.It is also a good source of essential fatty acids, fiber, minerals (especially calcium and iron), and phytochemicals such as polyphenols and phytates (Baye, 2014;Zhu, 2018;Girija et al., 2022;Yisak et al., 2022).Pertinently, the compositional abundance of such biomolecules may be suitably exploited as prospective bio-reductant and stabilizing agent in the green synthesis of nanomaterials such as silver nanoparticles.Till date there exists very few reports on the use of teff in the domain of nanotechnology.High temperature and toxic reagents like H2SO4 and HCl have been used to prepare nanosilica from teff straw (Bageru et al., 2017).Similarly, response surface methodology (RSM) has been resorted to prepare teff straw-based silica nanoparticles in a recent work (Amibo et al., 2022).On the other hand, Bacha and Demsash (2021) had reported the extraction of nanocellulose from teff straw using hot water treatment, acid-chlorite delignification, and alkaline hydrolysis process.Barring this, not much has been delved into the use of this extremely prospective bioresource for nanotechnological applications in accordance to the dictates of 'green nanotechnology' which focuses on resorting to preparation of nanomaterials under ambient conditions, use of less toxic reagents and lesser energy expense besides water as the reaction medium, as highlighted in the introductory section.Dictated by the afore-stated information, we proposed to develop an environmentally benign approach using water as the solvent and exploitation of the various biomolecules in aqueous extract of teff for the preparation and stabilization of silver nanoparticles (TSNPs) for a range of applications.This stems from the following hypothesis: Teff seeds (Baye, 2014) are a source of both bound and free polyphenols such as catechin, ferulic, rosmarinic, protocatechuic, p-coumaric acids as well phytosterols and vitamins.High abundance of proteins, carbohydrates, fibers, and other minerals has been documented.The compositional abundance of various polyphenolic compounds and biomacromolecules in the aqueous extract of teff powder could be bracketed together with its plausible bio-reductive potency to generate silver nanoparticles from silver salt as well as endowing of electrostatic and steric stability to the nanoparticles.Furthermore, a high surface to volume ratio of the prepared nanoparticles is envisaged, implying a highly active surface (dictated by shape-size-surface chemistry accord) could be exploited for multiple applications like catalysis etc.
Silver-based nanomaterials have etched an indelible mark in multiple domains.The green synthesis of silver nanoparticles has received significant attention over the last few years vis-à-vis the conventional use of toxic chemicals and reagents in the preparatory stages.In this milieu, the work reported here highlights the use of an aqueous extract of teff (Eragrostis tef) flour to prepare silver nanoparticles (TSNPs).The compositional abundance of various phytochemicals, sunlight-induced bio-reduction of silver ions, and subsequent stabilization of the nanostructures by teff's biomolecules were adroitly exploited.UV-visible spectroscopic analysis was employed to track the evolution of the TSNPs over time and their month-long storage stability.Exhibiting λmax at around 426 nm and energy gap (as revealed by Tauc's plot) of 2.26 eV, the silver nanomaterial was employed for methylene blue dye degradation (50% degradation in less than 20 min) and DPPH scavenging (IC50 = 243.42μL containing 410 μg of TSNPs), attesting their catalytic and anti-oxidant potency.On the other hand, anticoagulant action and a concentration-dependent variation were noted for radicle length post germination of Cicer arientinum seeds, treated with the TSNPs.The TSNPs could have profound implications in multiple domains.

MATERIALS AND METHODS
Teff based aqueous extract mediated reduction 3 g white teff flour (procured from local market), suspended in 100 mL of double distilled water was subjected to overnight stirring over a magnetic stirrer (the ambient temperature was ~25 o C) and subsequent filtration through a muslin cloth to prepare teff based aqueous extract.Aqueous solution of silver nitrate (AgNO3) (Abron Chemicals, India) was subjected to reduction using the teff extract, added drop by drop, followed by gentle manual swirling of the contents in conical flasks (replicates of three for various experimental conditions).The reaction was carried out in (a) a dark-chamber (the ambient temperature was ~23 o C), (b) under ambient light of the laboratory (the ambient temperature was ~24.5 o C) and (c) under sunlight (the ambient temperature was ~30 o C), using the reducing agent and the silver nitrate solution, adjusted to different v/v ratios (1:1, 1:2.2:1) while the variations in the molarity of the silver nitrate solution were 0.01, 0.02, and 0.03 M. Monitoring the rapidity of visible color-change (indicating the reduction of the silver ions and consequent formation of nanoparticles) and UV-visible spectral analysis assisted in choosing the reaction-conditions (dictated by the objective of preparing nanoparticles with narrow-size distribution/ lesser polydispersity).These initial studies had dictated us to select the parameters of 2:1 (v/v) reducing agent: silver salt (0.01 M) solution for the preparation of the nanoparticles under sunlight.The results reported in this work are for the nanoparticles prepared under these parameters.

UV-visible spectroscopic characterization
The time-course dependent formation as well as a month-long dependent storage stability of the TSNPs were monitored using BIOCHROM Libra UV-visible double-beam spectrophotometer (scanning range: 300-700 nm, path length: 10 mm, bandwidth: 1 nm, single-cycle).Tauc's plot was used to calculate the band gap energy of the TSNPs.All the graphs were plotted and analyzed using the OriginPro 8 software.

Dye decolorization test (to check the prospective application as catalyst)
1 mg of methylene blue (MB) (Abron Chemicals, India) was dissolved in 100 mL of distilled water and its absorbance was monitored spectrophotometrically.The experiment was conducted by adding 1 mL of freshly prepared 0.2 M NaBH4 (SRL Chemicals, India) to 25 mL aqueous solution of MB at room temperature (~25 o C).To this 1 mL of TSNPs was added and the reactants were vortexed.At a regular interval of time, 250 μL of the reaction mixture was withdrawn and diluted with 2.75 mL distilled water.The absorption of the mixture was monitored periodically using UV-visible spectrophotometer.The degradation was also monitored without the TSNPs.The reaction kinetics were evaluated by assuming the concentration of reactive dyes obeying the pseudo-first order reaction, where the integrated form is expressed as follows: where, A0 is the absorbance at zero time, At is the absorbance at time t, and k is the rate constant

DPPH scavenging test (to check the prospective application as anti-oxidant)
Antioxidant activity of the TSNPs was measured by using the modified DPPH method as reported previously (Konwarh et al., 2011).To examine the antioxidant potency, 200 μL, 400 μL, 600 μL, 800 μL and 1000 μL of the TSNPs were mixed with 2 mL of 100 μM DPPH (SRL Chemicals, India) solution.The samples were vortexed for around 15 s and allowed to scavenge DPPH in dark for 30 min.
The absorbance of the samples was measured at 517 nm.In all the cases, measurements were done in triplicates.The scavenging percentage was calculated using the formula: where AC and AS are absorption of blank DPPH and DPPH subjected to interact with the TSNPs at 517 nm, respectively.

Anticoagulant activity assessment
The experimental protocol to test the anticoagulant activity of the TSNPs was adopted from previously published report (Raja et al., 2015).Briefly, blood was collected from a healthy volunteer (post receipt of appropriate written consent) in different vials (C, S, T) without any anticoagulant by medical personnel, stationed at AASTU health-center.Immediately, TSNPs and teff extract were added to the tube S and T respectively at 0.5% (v/v) and anticoagulant activity of the samples was assessed.EDTA-tube (marked as E) served as positive control while vial C served as negative control.This experiment was approved by the B.Sc. Project Proposal Evaluation Committee, Department of Biotechnology, AASTU.

Effect on seed germination (Phyto-compatibility assessment)
Assessing the phytotoxicity of nanoparticles (Konwarh et al., 2011) was our next objective.For this, Cicer arientinum (chick pea) seeds were procured from the local market.The average germination rates of the Cicer arientinum seeds were greater than 95% as revealed in our initial experimentation.Seeds were kept in a dry and dark place at room temperature before use.These were surface sterilized in 1:1 volume of 3% hydrogen peroxide (SRL Chemicals, India) for 10 min, followed by rinsing thrice with distilled water.About 15 seeds were then soaked in distilled water (control) or nanoparticle suspension, taken in different concentrations for about 12 h.The soaking process resulted in imbibition and consequent swelling in all the seeds.The water and the nanoparticles suspension were drained off post soaking.The seeds were then, placed (with sufficient distance between each seed) on a piece of cotton filter-cloth (10 cm x 10 cm), taken on a Petri dish.The Petri dishes were incubated in the dark for 3 days (room temperature: ~ 26.5 0 C).Number of seeds germinated for each treatment as well as the length of the emanating radicles were noted.The experiment was conducted in replicates of three and the results were expressed as mean ± standard deviation.In conjunction to the above tests, the seeds were also soaked and incubated in the aqueous teff extract.

Preparation and UV-visible spectroscopic analysis
In the present study, the first objective was to use the aqueous extract of teff flour to prepare the TSNPs.The optical properties of nanoparticles are sensitive to size, shape, concentration, agglomeration state, and refractive index near the nanoparticle surface, therefore, UV-visible/IR spectroscopy serve as tools of immense pertinence in identifying and characterizing these materials.The UVvisible spectra supported the successful green-route mediated generation of the silver nanoparticles.No absorption peak was observed in UV-visible spectrum of Ag + solution before reduction (Figure 1).This is attributed to Ag + ions' d 10 configuration (Konwarh et al., 2011).In our pursuit to 'go green' we had resorted to the use of sunlight as catalyst for the generation of the nanoparticles.Initially, we had tried to reduce the silver salt under (a) dark condition and (b) ambient light condition of the laboratory at room temperature.Although, there was visible color change (colorless to yellow, indicative of the reduction of the silver salt), it took considerably a long time (more than an hour) in both the cases.For the photo-assisted preparation, the gradual generation of silver nanoparticles, using 2: 1 ratio of the reducing agent and silver nitrate solution, was indicated by the progressive increase (till 22 min) in the absorbance intensity at around 420-430 nm in the UV-visible spectra.This is attributable to silver's surface plasmon resonance (SPR) (Figure 1).The optical absorption of metal nanoparticles has been described traditionally and classically by Mie theory (Mie, 1908) as the localized surface plasmon resonance (LSPR).The optical absorption of metal nanoparticles can be described quantum mechanically due to intra-band excitations of conduction electrons by photon, mimicking the interactions of light on metal surface via the photoelectric absorption and Compton scattering.Plasmonic coupling of metal nanoparticles with light augments several useful optical phenomena that find application in ultrasensitive biomolecular detection and lab-on-a-chip sensors.Furthermore, we had also assessed the prospects of preparing nanoparticles using solutions of varied ratios of the reducing agent and the silver salt.However, the preparation using 1:1 and 1:2 ratios required considerably long time and was associated with the appearance of a broad SPR peak, at around 450 nm, indicating considerably large particle size and polydisperse nanoparticles.Thus, we had resorted to proceed with the nanoparticles, prepared using 2:1 reducing agent to silver salt solution.
Figure 1 UV-vis spectra of the aqueous extract of teff flour, the aqueous solution of the silver salt, and the TSNPs that exhibit SPR at 426 nm.The evolution of silver nanoparticles over time is depicted.
The rapid generation of the silver nanoparticles under the influence of sunlight (photo-induced bio-reduction) could possibly be due to photo-induced homolytic cleavage of the O-H bond of the various bio-reductants (example, amino acids) to form hydrogen radical that eventually transfers its electron to silver ion (Ag + ), generating silver nanoparticles.The oxygen radical part attains stabilization in the solution through extended conjugation.On the other hand, the compositional abundance of the biopolymers like starch in the teff extract is expected to confer steric stabilization to the nanoparticles (Figure 2).Based on the UV-visible spectral analysis, we then proceeded with the calculation of the band gap in the prepared TSNPs.Nanoparticles are larger than individual atoms and molecules but are smaller than bulk solid.They obey neither absolute quantum chemistry nor laws of classical physics and have properties that differ markedly from those expected.The effect of size quantization particularly in metals and semiconductors is profound.The size of a nanoparticle is comparable to the de Broglie wavelength of its charge carriers (i.e., electrons and holes).Due to the spatial confinement of the charge carriers, the edge of the valence and conduction bands split into discrete, quantized, electronic levels (Figure 3).These electronic levels are like those in atoms and molecules.The spacing of the electronic levels and the bandgap increases with decreasing particle size.This is because the electron hole pairs are now much closer together and the Coulombic interaction between them can no longer be neglected, giving an overall higher kinetic energy.This increase in bandgap can be observed experimentally by the blue-shift in the absorption spectrum or sometimes even visually by the color of the samples.A larger bandgap means that more energy is required to excite an electron from the valance band to the conduction band and hence light of a higher frequency and lower wavelength would be absorbed.

Figure 3 Band-gap change in nanoparticles
The maximum absorbance wavelength is associated with the conduction band energy according to quantum theory of metal nanoparticles (Gharibshahi et al., 2017).The conduction band energy of Ag nanoparticles can be calculated indirectly from the absorption spectra by the following Tauc's equation: where α is the absorption coefficient, hv is the photon energy, Ecb is the conduction band energy, and B is a constant.According to this equation, by plotting the (αhν) 2 versus energy and extrapolation of the linear part of the curve to the energy axis, the conduction band energy of Ag nanoparticles can be obtained as shown in Figure 4.The band gap for the TSNPs was calculated as 2.26 eV.This is quite high compared to bulk silver (0 eV) and in lines with previously reported values for nanoparticles (Banerjee et al., 2008;Yukna, 2007;Gharibshahi et al., 2017).
Figure 4 [A] UV-visible spectrum of the TSNPs, [B] Tauc plot, Variation of (αhν) 2 with eV for Ag nanoparticles as a function of wavelength We had also resorted to the UV-visible spectroscopic studies to understand the storage stability of the nanoparticles under room temperature (~23-26 O C).In our case, post storage of the TSNPs for a month, a slight shift of SPR peak (from 426 nm to 430 nm) was observed, however, the peak width remained the same (Figure 5).The biomolecules present in the teff flour extract were envisaged to act both as the reducing and stabilizing agent, thereby preventing excess aggregation of the nanoparticles.It is pertinent to note that scattering from a sample is typically highly sensitive to the aggregation state of the sample, with scattering contribution augmenting with the increase in the aggregation of the particles.
Figure 5 UV-visible spectra demonstrating the considerable stability of the nanoparticles, stored under ambient conditions over a month The optical attributes of nanoparticles may be altered when particles aggregate and the conduction electrons (as in silver nanoparticles) near each particle surface become delocalized and are shared amidst the neighboring particles.Occurrence of such events leads to shifting of the SPR to lower energies, causing the absorption and scattering peaks to exhibit red-shift to longer wavelengths.
(Due to inaccessibility of other characterization tools (DLS, zeta potential, HRTEM etc.) during the execution of this B.Sc. project work in Ethiopia, we could not present a complete landscape of the physicochemical characterization of the nanoparticles.Nevertheless, the UV-visible spectroscopic analysis attested or at least indicated the successful preparation of the TSNPs.Thus, we proceeded with our investigation into their prospective applications and preliminary delving of their action at the bio-interface.)

Dye decolorization (application as catalyst)
Use of various dyes in paper, plastic, leather, food, cosmetic and textile industries have led to multiple issues including skin irritation, liver, kidney damage as well as the widespread application could prove detrimental to the central nervous system and even result in mutation and cancer (Latha et al., 2019).The need of the hour is to mitigate the various synthetic dyes economically and safely in the environment.Amongst others, techniques such as carbon sorption, redox treatment, phyco-remediation, UV-light mediated degradation etc., have been explored (Latha et al., 2019).Use of nanoparticles for dye-abatement (Fairuzi et al., 2018) has been proposed as a rapid, low-cost methodology (without the formation of polycyclic products and oxidation of pollutants).In this regard, we had resorted to test the efficacy of the TSNPs for decolorization of methylene blue (MB), a common cationic dye.We found that the TSNPs functioned as an efficient catalyst (Figure 6   The degradation-percentage (%) of the dye was calculated by using the formula: Dye degradation (%) = {(A0 -A/A0)} x 100 … [4] where, A0 is the initial concentration of MB solution and A is the concentration after t minutes of reaction.
In the absence of the nanocatalyst, the dye-decolorization was found to the negligible.Addition of the nanoparticles resulted in more than 50% decolorization in less than 20 min.The kinetic data were fitted to first order rate equations value (Figure 6 [C]).The nanoparticles are envisaged to act as electron relay and initiate shifting of electron from BH 4-ion (donor B2H4/BH4 -) to acceptor (acceptor LMB/MB), leading to reduction of the dye.Concomitant adsorption of the BH 4- ion on the surface of the nanoparticles is followed by electron transfer from the BH4 -ion into the dye via the nanoparticles (Kumari et al., 2015).Highlights of a few studies on MB dye degradation using silver nanoparticles, fabricated using phyto-extracts are presented in Table 1.

DPPH scavenging (application as anti-oxidant)
The free radical scavenging of the TSNPs was evaluated in the present study.The percent scavenging of DPPH increased almost linearly with the increase in the concentration of the nanoparticles in the test samples (Figure 7).From the plot, 50% DPPH scavenging was calculated for 243.42 μL of the TSNPs.Previously, Lalsangpuii et al. (2022) had reported that the DPPH scavenging activities of AgNPs, prepared using Spilanthes acmella leaf extract (IC50: 3.85 ± 0.04 μg/mL) was significantly higher than that of S. acmella leaf extract (SAAE) (IC50: 474.0 ± 8.80 μg/mL).On the other hand, AgNPs, fabricated using spice blend of garlic, ginger and cayenne pepper exhibited greater inhibition of DPPH radical with IC50 < 31.25 µg/mL against 68.75 µg/mL for 2,2՛-azinobis (3ethylbenzothiazoline-6-sulfonic acid) or ABTS (Otunola and Afolayan, 2018).IC50 values of 385.87 µg/mL and 30.04 µg/mL for DPPH scavenging was recorded for AgNPs, prepared using aqueous extract of silk hair of corn (Patra and Baek, 2016) and Erythrina suberosa (Roxb.)(Mohanta et al., 2017) respectively.Recent work has unmasked IC50 values of 82 ± 0.079, 44.56 ± 0.02 and 26.6 ± 0.06 µg/mL corresponding to flaxseed extract, AgNPs, fabricated using flaxseed extract, and ascorbic acid respectively (Alzubaidi et al., 2023).Previously, the corresponding author of this work had also reported DPPH based antioxidant activity of Colocasia esculenta based silver nanoparticles (Barua et al., 2013) besides free radical scavenging using orange peel-based silver nanoparticles (Konwarh et al., 2011).Numerous anti-oxidants of the orange peel (pooled into the system during preparation and consequently surface-adsorbed) were proposed to act synergistically in that system.Furthermore, with a high surface area to volume ratio and an ambient electrostatic field with anti-oxidant bio-moieties on the surface, these silver nanoparticles were anticipated to develop a high tendency to interact with and reduce DPPH like species.In this work, although, a higher volume was required for our sample (in comparison to previous work, as reported by Konwarh et al. (2011), possibly due to lesser abundance of polyphenolic compounds in teff compared to orange peel) to display 50% scavenging, nevertheless, it raises the prospects of incorporating the prepared nanoparticles for developing of nanocomposite packaging materials with the facet of free radical scavenging.The nano-chemistry involved in this free radical scavenging attribute of the nanoparticles needs further investigation, besides appropriate dilutions and concentrations are important aspects in anti-oxidant assays.Exotics like nanoparticles can penetrate via the cell wall, primarily composed of polymeric carbohydrates, prior to membrane invagination in plant cells (Konwarh et al., 2011) and can lead to alteration in various physiological activities of the plants.In this backdrop, investigation of the modulation of the phyto-physiology, assessed in terms of seed germination due to the plausible penetration of the TSNPs was one of the propositions in this work (Figure 9).Plant seeds with emerging radicle or cotyledon coming out of the seed coat were recorded as being germinated in the present experiment.In our experiment, it was observed that the average germination rate remained unchanged for the treated seeds with respect to the control.However, significant difference was noted for the average radicle length post four days of incubation (Table 2).2018).Furthermore, AgNPs, synthesized using Aloe vera leaf extract (Anju, 2022) supported significant increment in biomass, shoot, and root growth in C. arientinum L. On the other hand, biosynthesized iron oxide nanoparticles (IONPs) have been found to support callus induction, shoot regeneration and root induction of chickpea plants for prospective application in plant tissue culture (Irum et al., 2020).Pawar et al. (2019) had also assessed the impact of iron oxide nanoparticles (Fe2O3 NPs) on chickpea seedling growth using different concentrations (4-16 μg/mL).They found that lower concentrations (up to 12 μg/mL) enhanced seed germination and growth, but higher concentrations were inhibitory.Our preliminary investigation has shown that TSNPs do have a phyto-physiology modulatory effect, as reflected in the varied lengths of the emerging radicle.It is to be noted that the aqueous teff extract did not influence the seed-germination negatively and the results were in lines parallel to that of the control.As far as this study is concerned, besides delving into the effect on the shoot length and survival percentage of the seedlings post transplantation, a number of questions have to be addressed: Will the effect of the prepared samples and the consequences of the internalization and bio-distribution be same for both dicot and monocot plants?Is the phyto-modulatory action species-specific?Does the penetration of Ag NPs into the root cells help the plants to ward off soil pathogens or lead to the loss of beneficial microflora, peripheral to the roots?

CONCLUSION
This work mirrors the successful sunlight-assisted rapid and efficient biogenic synthesis of silver nanoparticles using aqueous teff powder extract (without any additional toxic chemicals), for multiple applications.However, the complete physicochemical attributes of the nanoparticles have not been investigated.The work reported in this work brings the fact to light that a common raw material of the Ethiopian food-delicacy can be useful even in the domain of nanotechnology.The stabilized silver nanoparticles synthesized under the ambient conditions shows tremendous potential for applications in several realms.These nanoparticles endowed with the attributes of free radical scavenging, catalysis, and anticoagulant potency as well as phyto-compatibility (as revealed in preliminary investigations) may be exploited for various biomedical, agricultural, and industrial applications.Furthermore, probing into the nano-biointerfacial actions at various levels could be the focus of future study.To cite for evidence, effect of the silver nanoparticles on PCR amplification of genes of interest, antimicrobial potency as well as in vivo effects could be investigated.
, the greener fabrication protocols primarily involve water as the reaction medium and/or other green chemistry approaches/tools such as green eutectic solvents (Nam et al., 2023), sono-chemical approach (Joshi et al., 2023) and microwave irradiation (Kaur et al., 2023).Such green methods are envisaged to reduce the environmental footprint besides offering advantages, including cost-effectiveness and the ability to control particle size and shape, although, structural and functional complexity of nanomaterials, fabricated using greener routes demand deeper delving (Santo-Orihuela et al., 2023).The potential use of green-synthesized nanomaterials spans across diverse domains, from medicine and catalysis to environmental remediation and sustainable energy solutions, driving the development of a future based on cleaner and sustainable technological applications (Rani et al., 2023; Sani et al., 2023; Ramezani Farani et al., 2023).Amongst others, the recent use of various phytoextracts, such as Terminalia paniculata Roth based antioxidant and antiinflammatory silver nanoparticles (Vernekar and Taranath, 2023); banana pith extract based antibacterial and catalytic gold nanoparticles (Nayak et al., 2018); Syzigium cumini leaf extract based iron oxide nanoparticles for prospective nanobiofertilizer applications for optimizing legume production (Saleem and Khan, 2023); and Moringa oleifera extract based copper oxide nanoparticles for energy storage applications (Ikhioya et al., 2023) etc. merits special mention.

Figure 2
Figure 2 Schematic representation of photo-induced bioreduction of the silver ions based on the aqueous extract of teff flour and the subsequent generation of stable silver nanoparticles [A]) in decolorizing aqueous MB in presence of NaBH4.The decrease of absorbance at λmax (664 nm) of MB with time was followed spectrophotometrically.The bar diagram depicts the percentage of MB degradation with exposure time (Figure 6 [B]).

Figure 6
Figure 6 [A] Time-course-dependent absorption spectra of the MB solution in the presence of the TSNPs.[B] Percentage of dye degradation with respect to time [C] Kinetics of MB decolourization by the TSNPs

Figure 7
Figure 7 DPPH scavenging activity of the silver nanoparticles

Figure 8
Figure 8 Anticoagulant activity assessment of the TSNPs on blood collected freshly from a healthy volunteer

Figure 9
Figure 9 [A] Treatment of Cicer arientinum seeds with different concentrations of TSNPs [B] Representative batch of germinated seeds, post three days of treatments [C] Representative seeds with emanating radicles.Here, C refers to the control (without any treatment), while for codes 1-6, readers are requested to refer to Table2In our experiment, it was observed that the average germination rate remained unchanged for the treated seeds with respect to the control.However, significant difference was noted for the average radicle length post four days of incubation (Table2).

Table 2
Phytotoxicity assessment of the TSNPs -on germination and radicle length of Cicer arientinum

Sample Average germination rate (%) of the seeds Average radicle length (cm) post four days of incubation
(Farhana et al., 2022)to a wide range of environmental changes.Additionally, it exhibits convenient germination with its thin seed coat.Pertinently, Candan et al. (2022) reported the application of infrared spectral analysis, aided by machine learning techniques to unveil that gold nanoparticles (AuNPs) and single-walled carbon nanotubes (CNTs) are taken up by C. arietinum seedlings' root, leading to consequent build-up of the nanomaterials in stem and leaf parts.Priming Cicer arientinum seeds with ZnO NPs (synthesized using Trichoderma harzianum) was projected as a means to aid chick pea plants to pile up greater amounts of sugars, phenol, total proteins, and superoxide dismutase (SOD) to resist wilt pathogen-Fusarium oxysporum(Farhana et al., 2022).Similar protective action of treatment with AgNPs (biosynthesized by rhizopheric microflora of chick pea) against wilt disease was previously reported by Kaur et al.( (Madurapperumage et al., 2021)seed priming using ZnO-NPs and 24-epibrassinolide (EBL), whether applied separately or together, resulted in improved seed germination and boosted the metabolic and homeostatic response in maize seeds cultivated under salt stress in comparison to the control group(Alhammad et al., 2023).Similarly, Acharya et al. (2020) had reported that Ag NP-mediated seed priming resulted in better germination, growth, yield as well as maintained fruit quality in Citrulllus lanatus (watermelons).However, there exist contrasting reports on the phytomodulatory effects of different nanoparticles.Shi et al. (2019) had reported the germinationinhibitory effect of gold nanoparticles on mung-bean (Phaseolus radiatus).androotgrowthwhichwas evident from the increased length and biomass of rice seedlings(Gupta et al., 2018).Exposure to AgNPs was also found to significantly increase the chlorophyll a and carotenoid contents.The molecular basis of these observation needs further investigation.Cicer arietinum L., a dicotyledonous plant was chosen to assess the preliminary phytotoxicity of the prepared silver nanoparticles in this work.C. arientinum L. or chick pea, an important pulse crop(Madurapperumage et al., 2021)acts as a great source of protein, fats and carbohydrates besides serving as a green manure and fodder for animals.It is readily accessible and manageable, capable of being cultivated throughout