Lichen is one of the most abundant non-vascular biomasses; however, a systematic study on the application of biomass in nanomaterial synthesis is very limited. In this study an aqueous lichen extract was obtained from Hypotrachyna cirrhata, one of the most abundant Himalayan lichen biomasses, using a simple cold percolation method. The effects of extract-to-silver nitrate mixing ratio, pH and waiting time on the growth and stability of nanoparticles were systematically explored. The rate constant for bio-reduction was found to be 5.3 x 10-3 min-1. Transmission electron microscopy showed a narrow particle size distribution with a mean particle size of 11.1 ± 3.6 nm (и = 200). The X-ray diffraction and selected area electron diffraction techniques confirmed the formation of cubic crystals. The synthesized colloidal solution showed excellent response to Hg2+ and Cu2+ ions in spiked water samples. The limit of detection and calibration sensitivity for Hg2+ and Cu2+ ions were found to be 1 and 5 mg 1-1 and 2.9 x 10-3 and 1.6 x 10-3 units ppm-1, respectively. These findings suggested that spherical silver nanoparticles with a narrow particle size distribution can be synthesized on a laboratory scale using an aqueous H. cirrhata lichen extract, and the colloidal solution can be used for the detection of selected heavy metals in water samples.
Keywords:
growth kinetics, heavy metals, materials science, nanoparticles, surface plasmon resonance
1. Introduction
Nanostructured materials have individual domains or units in the size range of 1-100 nm. In recent decades, such materials have been of interest mostly in physics, chemistry biology and engineering disciplines. Nanomaterials of the size range of 1-20 nm are of special interest as they offer unique physico-chemical properties such as high surface-to-volume ratio and high diffusion rates. They are widely explored for biomedical [1], optoelectronic [2,3], catalytic [4,5], sensing and several other applications [6]. Nanomaterials having diverse chemical composition and morphology are being explored. Based on morphology, nanomaterials can be broadly classified into three-dimensional, two-dimensional, one-dimensional and zero-dimensional [7]. Particles having diverse morphology, such as nanospheres [8], nanorods [9], nanoclusters [10], nanodots [11], nanowires, nanosheets [12], nanocubes and nanoboxes [13], are reported. Such materials are also finding applications in cosmetics [14], healthcare [15,16], food industries [15,17] and environmental remediation [18].
Several methods for nanomaterial synthesis are available, and these methods can be broadly classified into physical, chemical and biological methods [19]. Although physical methods, such as the chemical vapour deposition technique, avoid solvent contamination and offer large-scale production, they require sophisticated instrumentation and high energy for evaporation and condensation of particles, and normally result in broad size distribution. In chemical techniques, suitable reducing and capping agents are used to synthesize nanoparticles with a narrow particle size distribution. Although traditional wet methods normally do not require sophisticated instrumentation, toxic precursors and small-scale production are the limitations. In biological methods, the precursors needed for the reduction and stabilization are obtained from microorganisms (fungi and bacteria), plant extracts and metabolites [19-29]. Although size control and small-scale production are challenges, the method is being explored as a cost-effective and eco-friendly method for nanoparticle synthesis [20,30].
The spherical nanoparticles of silver, gold and copper are of special interest due to their low toxicity, high stability and ease of synthesis and functionalization for biomedical and sensing applications [8,16,20,31,32]. In recent decades, these particles have been synthesized on a laboratory scale using crude and/or partially purified extracts and metabolites obtained from the root, leaf, stem, flower and fruit parts of various plants [19-24]. The extract obtained from algae, fungi and mushrooms is also being explored for green synthesis [25,26,33-36]. However, to get nanoparticles of stable size and shape, several parameters, such as composition, metal salt-to-extract ratio, waiting time and pH, have to be controlled.
Lichen biomass is one of the most abundant non-vascular biomasses on the earth's surface. The biomass is found on tree trunks and branches. The degree of colonization and distribution is determined by host attributes and climatic variation [37]. The biomass is found useful in making dyes and perfumes, as food, in traditional medicine and as bio-indicators [38,39]. Applications of lichen biomass in the green synthesis of metallic nanoparticles are also reported in many studies [40-46]. The majority of the studies are focused on antimicrobial applications. Therefore, it would be interesting to explore the heavy metal-sensing potential of nanoparticles.
In this study, the application of the aqueous extract obtained from Hypotrachyna cirrhata, one of the most abundant high-altitude lichen species in the Himalayan region of Nepal, is systematically explored for the synthesis of silver nanoparticles (AgNPs). The effects of extract-to-metal salt ratio, pH and waiting time on growth kinetics and stability of AgNPs are systematically explored. The synthesized nanoparticles are characterized using UV-visible (Vis), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. Finally, the sensing potential of the colloidal solution for 10 metal ions in spiked water samples is explored.
2. Experimental section
2.1. Materials
Lichen biomass was collected from an altitude of 2300 m in Daman (latitude 27.6081833 and longitude 85.0922813), Makwanpur district of central Nepal. The lichen species were identified to be H. cirrhata (Fr.) Divakar, A. Crespo, Sipman, Elix and Lumbsch (figure 1) in the National Herbarium and Plant Laboratories, Department of Plant Resources, Ministry of Forests and Environment, Nepal. Permission to harvest lichen for the scientific study was obtained from the Department of Plant Resources, Ministry of Forests and Environment, Nepal (letter number 2076/77-264).
The biomass was rinsed adequately with running tap water, followed by distilled water, and then dried at room temperature in the shade for 2 weeks. An electrical blender was used to grind the biomass into powder and then stored in polyethylene bags for further use. The stock lichen extract solution was prepared by adding 2 g of lichen powder to 100 ml of distilled water. The content was mixed using a magnetic stirrer at 90°C for 30 min, cooled and filtered through a Whatman filter paper (WHA7404004, 47 mm diameter and 0.45 pm pore size). The filtrate was stored at 4°C in the dark for further experiments.
2.2. Biosynthesis of silver nanoparticles
A stock solution of 50 mM AgNOg was prepared by dissolving 4.25 g of AgNO3 in 500 ml distilled water in a volumetric flask. Next, 10 ml of the stock solution was diluted to 500 ml to prepare 1 mM of AgNO3 to synthesize AgNPs. The lichen extract was then mixed with the silver nitrate solution in different volume ratios while being mixed using a magnetic stirrer at room temperature. The visual change in colour of the solution from yellow to dark brown was noted.
The kinetics of bio-reduction was monitored by recording surface plasmon resonance (SPR) spectra in the range of 300-700 nm (UV-1900 spectrophotometer; Shimadzu) from shorter to longer time at a fixed pH and silver nitrate:lichen extract volume ratio. The effects of pH on the SPR spectra were investigated by varying the pH of the growth solution from 2 to 12 using a 0.1 M NaOH solution while maintaining the composition of silver nitrate and extract constant.
2.3. Characterization of nanoparticles
The zeta potential was measured using a zeta sizer (SZ-100; HORIBA Scientific). Before measurement, particles were dispersed in distilled water and sonicated for 10 min. The scattering angle, sample holder temperature and dispersion medium viscosity were 90°, 25.0°C and 0.896 mPas, respectively.
The Fourier-transform infrared spectroscopy (FTIR) measurement of the lichen extract was taken in an attenuated total reflection mode (Nicolet; Thermo Fisher Scientific) in the range of 400-4000 cm-1. The spectral resolution and the number of scans during the measurement were set to 4 cm-1 and 100, respectively.
For XRD measurement, the nanoparticle solution was centrifuged at 9000 r.p.m. (Sorvall ST 8R centrifuge) for 20 min at 25°C. The supernatant was discarded, and the pellet was re-dispersed in distilled water. The centrifugation process was repeated three times to wash off any adsorbed substance on the surface of AgNPs and finally washed with absolute ethanol. The content was dried at room temperature and stored in an Eppendorf tube covered with aluminium foil. The XRD data of the nanopowder were collected using an X-ray diffractometer (MiniFlex 600; Rigaku), consisting of CuKa (À = 1.540Å) as an X-ray source. The step size, scanning range and scanning speed were set to 0.05°, 20-90° and 0.25° s-1, respectively.
SEM images and energy-dispersive X-ray (EDX) spectra were measured with a field-emission scanning electron microscope (JEOL). The particles were dispersed on a carbon tape and sputter coated with Au. For ТЕМ analysis, the colloidal suspension was deposited on a copper grid. ТЕМ images and selected area diffraction or selected area electron diffraction (SAED) patterns were measured using a ТЕМ microscope (JEM-21 OOPlus; JEOL). The TEM images were analysed in Image J software (National Institues of Health, USA) to get information on particle size distribution.
2.4. Metal ion sensing
In a regular sensing test, 1 ml of the metal solution was added to 4 ml of the AgNP solution. The ions used for the tests were Fe2+, Ba2+, Hg2+, Cu2+, Mn2+, Zn2+, As3+, Ni2+, Cr3+ and Cd2+ at a concentration of 2.5 x 10-4 M. The colour change in the mixture was observed visually, and the SPR spectra were also measured to see the change in peak intensity, position and shape. The metal ions that showed a drastic change in SPR were spiked into the nanoparticle suspension to see the systematic change in SPR spectra. The spectra were analysed to get information on the limit of detection and the calibration sensitivity.
A schematic diagram that depicts the overall experimental design used in this work is provided in figure 1.
3. Results and discussion
3.1. Effect of precursor concentration
The growth of nanoparticles depends on several parameters such as extract-to-metal ion ratio, waiting time and pH. To explore the effect of volume ratios in the formation of nanoparticles, UV-Vis spectral change was recorded after a fixed waiting time of 24 h while varying the silver nitrate and lichen extract volume ratios from 1:1 to 1:9 (figure 2a). The pH in all cases was ~7.5. The spectral feature peaking at ~435 nm in all volume ratios is the SPR band. The feature provides strong evidence for AgNP formation. Other evidence is provided by the development of reddish-brown colouration on mixing a light yellowish extract solution with a colourless silver nitrate solution (figure lb).
The pH of the mixture was -7.5 in all cases, so the difference in spectral shape (figure 2a) is mainly attributed to compositional variation. A well-defined and intense SPR was observed when the extract-to-silver nitrate volume ratio was 1:1. The SPR band is also symmetric. This could suggest that at a 1:1 volume ratio, AgNPs having a narrower particle size distribution could have formed. Direct evidence for the particle size distribution can be obtained from transmission electron microscopic images reported in the later section.
The nanoparticle growth kinetics could involve reduction of Ag+ to Ag° state, formation of silver nuclei and the growth of nuclei to AgNPs. The reduction could be due to electron-donating moieties, such as -OH and -NH2 groups present in the organic precursors, or phytochemicals, such as polyphenols and proteins. The organic precursors could also help in capping and stabilization of nanoparticles [20-22,30,47].
Preliminary information on the presence of different precursors involved in bio-reduction can be obtained from the FTIR spectra of the extract (figure 2c). A broad and asymmetric band in the range of 3000-3600 cm-1 and peak -3300 cm-1 can have mixed contributions from the stretching vibration of phenolic -О-H and protein -N-H. The bands observed at -3400 and 2920 cm-1 can be assigned to the -C-H stretching vibrations of the primary and secondary amines, respectively. The band at ~1730 cm-1 could correspond to the -C=O stretching frequency of carboxylic anhydrides, ketones or lactones [48]. The bands at ~3400 and 1640 cm-1 can be attributed to -N-H stretching and bending vibrations in amines in proteins [49]. The band at ~2920 cm-1 could arise from C-H stretching, and at ~1530 cm-1 corresponds to C=C stretching vibration from aromatic rings of plant metabolites [21]. The peak at 1030 cm-1 can arise from either =C-H in-plane bending or -C-N stretching of aliphatic amines, and the band at ~1390 cm-1 arises from C=N stretching; the band at ~1140 cm-1 arises from C-О stretching phenol, ester or ether groups and the band at 1260 cm-1 arises from C-N stretching aromatic amines [48,50,51]. These signatures indicate that polyphenols, proteins or other plant metabolites present in lichen extract could be responsible for the reduction, capping and stabilization of the AgNPs.
3.2. Growth kinetics
At fixed precursor ratios and pH, SPR spectra were recorded from shorter to longer waiting times (figure 3a). As expected, the SPR peak intensity increases with waiting times. A small shift in peak position could be due to a change in particle size during nucleation and growth of nanoparticles.
The SPR spectra were further analysed to get information on the rate constant (k) for bio-reduction, considering a first-order kinetic model (equation (3.1)).
where Aoo, At and A0 are the SPR peak intensities at infinite waiting times (here 24 h), at time t and at zero time, respectively. Equation (3.1) suggests that the slope of log(Aoo - At) versus t plot provides information on the rate constant. Indeed, the first-order kinetic model fits well (R2 > 0.95) with the experimental data (figure 3b). The rate constant was found to be 5.3 x 10-3 min-1.
3.3. Effect of pH
To explore the effect of pH, UV-Vis spectra were recorded in the pH range of 2-12 at the fixed waiting time of 24 h (figure 4a). The corresponding visual colour change was also recorded at all pH ranges (figure 4b). The SPR spectra were also measured at a longer waiting time of 4 weeks to explore the stability of the nanoparticle solution (figure 4c).
At a shorter waiting time and a pH range of 4-11, a well-defined and symmetric SPR band is visible (figure 4a). At pH 2 and 12, the SPR band becomes more asymmetric with a shoulder of ~550 nm. The additional feature could be due to aggregation of nanoparticles. At a longer waiting time of 4 weeks (figure 4c) and a pH range of 4-11, the SPR spectral shape is unchanged. However, at pH of 2 and 12, the 550 nm feature becomes more pronounced. This could be due to an increase in the population of aggregated particles.
To gain more insight into the stability of colloidal solution, zeta potential values were measured. The zeta potential is a direct measure of the surface charge density. Colloidal particles having high zeta potential (both positive and negative values) tend to be stable, i.e. do not aggregate and flocculate, due to electrostatic repulsion. The zeta potential of AgNPs is slightly positive at low pH values (2, 4 and 6) and flips to negative values at pH > 7. The zeta potential is highest at pH 10. This could suggest that the particles remain most stable at this pH. For long-term stability, the zeta potential should remain stable over time. At pH 12, the zeta potential is significantly high. The particle aggregation at a longer waiting time, as indicated by the appearance of an additional band ~550-600 nm (figure 4c), could be due to unable charge density, i.e. decrease in zeta potential over time.
3.4. SEM and XRD measurements
The nanoparticle agglomerates or aggregates are visible in SEM images (figure 5a). Therefore, individual particle size information is difficult to obtain from the image. The agglomerate formation is a result of high surface energy and is commonly reported in SEM images of AgNPs synthesized using other plant extracts [48,51]. As expected, the SEM-EDX data showed distinct peak characteristics of silver (figure 5b). The additional peaks could come from impurities and Au used in the sample preparation.
In XRD data (figure 5c), the peaks at 20 values of 38.08°, 44.2°, 64.7° and 77.35° can be assigned to (111), (200), (220) and (311) diffraction planes of face-centred cubic structures of AgNPs [48,51,52]. The minor peaks at 27.95°, 32.28°, 46.2°, 55.12°, 57.2° and 81.5° could originate from Ag2O and/or AgCl nanoparticles [50,53,54] and are also reported in other studies [21,51]. These peaks might originate due to the oxidation of AgNPs during XRD sample preparation and measurement.
The XRD peak characteristics of the AgNPs were used to get information on inter-planar spacing (dhkl) and average crystallite size (L) (table 1). The dhkl was calculated using Bragg's equation:
where n = 1 (first-order diffraction), λ is the wavelength of the X-ray source (0.154 nm) and θ is the peak position (in radians).
The crystallite size (L) was calculated using the Debye-Scherrer equation [55].
where λ is the wavelength of the X-ray source (here 0.154 nm), ß is the full width at a half maximum of each diffraction peak (in radians) and θ is the peak position (in radians). The ß factor was measured using three major peaks at 38.08°, 64.7° and 77.35°. The average crystallite size was found to be 7.3 ± 0.5 nm (table 1).
3.5. ТЕМ imaging
TEM is the most important technique to get morphological information on metallic nanoparticles. ТЕМ images (figure 6a,b) show individual nanoparticles of spherical shape. The mean particle size obtained from the image analysis (n = 200) at 95% confidence interval was found to be 11.1 ± 0.5 nm and the particle size ranged from 4.2 to 29 nm. To show the particle size distribution, a histogram plot of 200 particles is also shown (figure 6c). Interestingly, the histogram can be fitted well with a narrow Gaussian curve, suggesting that particles are monodispersed. This observation is consistent with a symmetric SPR band observed in the UV-Vis spectra.
The SAED pattern of the nanoparticle sample was also measured to get further information on crystallinity. The SAED pattern showed four distinct and sharp concentric rings (figure 6d\ These rings indicate that particles are highly crystalline. The SAED patterns were analysed to get inter-planar spacing (dhkl) in Å following equation (3.4).
where a is the diameter of each concentric ring in nm-1. The inter-planar spacing (dhkl) was found to be 1.23Å, 2.35Å, 2.04Å, 1.41Å and 1.22Å. Interestingly, dhkl values obtained from SAED and XRD perfectly correlate (r = +0.99).
3.6. Calorimetric metal sensing
The calorimetric sensing potential of AgNP was tested for 10 heavy metals and trace elements. For preliminary screening, nanoparticle solution was spiked at a 2.5 x 10-4 M concentration of Fe2+, Ba2+, Hg2+, Cu2+, Mn2+, Zn2+, As3+, Ni2+, Cr3+ and Cd2+. The change in the SPR profile and the visual colour was recorded (figure 7a,b).
The SPR peak shows an ion-specific response. A decrease in peak intensity is observed in the presence of all ions. Additionally, the SPR band shifts either to blue or to red, with an increase in the bandwidth. For example, in the presence of Hg2+ and Cu2+, the SPR band almost disappears, and As3+ decreases the peak intensity along with the appearance of one additional band at -600 nm (figure 7 a). In a broader sense, the change in the spectral feature is due to the interaction of foreign ions with the biomolecule adsorbed on the surface of nanoparticles, which can lead to nanoparticle aggregation [56]. The spectral change also correlates with the colour change of the nanoparticle solution (figure 7b). Particularly, the addition of Hg2+ and Cu2+ converted the reddish-brown-coloured AgNP solution into a completely colourless solution. These observations suggest that the SPR band shows the maximum response with Cu2+ and Hg2+ ions.
The reduction potential of Hg2+/Hg is higher than that of Ag+/Ag system (E°Hg2+/Hg = +0.85 V and E°Ag+/Ag = +0.80 V). Therefore, a redox reaction is possible with the formation of metallic mercury. The newly formed metallic mercury could interact strongly with Ag, leading to the formation of amalgam on the surface of AgNPs. This could lead to the damping of SPR [21,57]. Similar reasoning could be applied to Cu2+.
To quantify the sensing performance, the nanoparticle solution was titrated with variable concentrations of Hg2+ and Cu2+, and a change in the SPR profile was recorded (figure 7c,e). The intensity change showed a linear response with the concentration of both ions (figure 7d,f). The calibration sensitivity as determined from the slope of the respective curves for Hg2+ and Cu2+ was found to be 1.6 x 10-3 and 2.9 x 10-3 units ppm-1, respectively. The limit of detection for Hg2+ and Cu2+ ions was found to be 1 and 5 mg 1-1, respectively. These findings suggest that green synthesis of spherical AgNPs is possible using aqueous lichen extract, and nanoparticles can be used for the detection of selected heavy metals.
4. Conclusions
In this study, the application of the aqueous lichen extract obtained from the high-altitude lichen species H. cirrhata was systematically explored for the synthesis of AgNPs. The most intense and sharp SPR band at ~435 nm was obtained in the UV-Vis spectra when the extract-to-Ag+ ratio was 1:1 (v/v) and at a pH range of 9-10. The nanocolloidal solution showed maximum stability at a pH range of 8-11, which is consistent with the high zeta potential in the pH range. The rate constant for bio-reduction was found to be 5.3 x 10-3 min-1. The mean particle size (n = 200) obtained from TEM was found to be 11.1 ± 3.6 nm. The SAED and XRD data indicated the formation of cubic crystals. The nanocolloidal solution showed excellent sensitivity for the presence of Hg2+ and Cu2+ ions in spiked water samples. The limit of detection and calibration sensitivity for ions were found to be 1 and 5 mg 1-1 and 1.6 x 10-3 and 2.9 x 10-3 units ppm-1, respectively. These findings suggested that green synthesis of spherical AgNPs having a narrow particle size distribution is possible using the aqueous lichen extract of H. cirrhata, and the colloidal solution can be used for the detection of selected heavy metals.
Ethics. This work did not require ethical approval from a human subject or animal welfare committee.
Data accessibility. The datasets are provided as electronic supplementary material [58].
Declaration of Al use. We have not used AI-assisted technologies in creating this article.
Authors' contributions. N.S.: investigation, resources, writing-original draft; S.K.G.: data curation, writing-review and editing; A.A.: conceptualization, supervision, writing-review and editing; conceptualization, funding acquisition, resources, supervision, validation, writing-review and editing.
All authors gave final approval for publication and agreed to be held accountable for the work performed therein.
Conflict of interest declaration. We declare that we have no competing interests.
Funding. This study was supported by the University Grants Commission, Nepal (to N.S.: no. PhD-S&T 6/076-077; to B.B.N.: no. CRIG-78/79-S&T-02).
Acknowledgements. The authors acknowledge Dr. Tista Prašai at the Nepal Academy of Science and Technology for supporting in zeta potential measurement and Prof. Dr. Rajiv Prakash, IIT, Bhilai, India, for supporting in ТЕМ measurement.
References
1. Anik Ml, Mahmud N, Al Masud A, Hasan M. 2022 Gold nanopartides (GNPs) in biomedical and clinical applications: a review, hano. Sel. 3,792-828. (doi:10.1002/nano.202100255)
2. Krishnaswamy JA, Ramamurthy PC, Hegde G, Mahapatra DR. 2022 Modelling and design of nanostructured optoelectronic devices: solar cells and photodetectors. New York, NY: Springer.
3. Manik G, Kumar Sahoo S. 2022 Applications of nanomaterials in energy storage and electronics. Sharjah: Bentham Science Publishers.
4. Li P et al. 2019 Metal-organic frameworks with photocatalytic bactericidal activity for integrated air cleaning. Nat. Commun. 10,2177. (doi:10. 1038/S41467-019-10218-9)
5. Qiu X, Zhang Y, Zhu Y, Long C, Su L, Liu S, Tang Z. 2021 Applications of nanomaterials in asymmetric photocatalysis: recent progress, challenges, and opportunities. Adv. Mater. 33, e2001731. (doi:10.1002/adma.202001731)
6. Prakash Sharma V, Sharma U, Chattopadhyay M, Shukla VN. 2018 Advance applications of nanomaterials: a review. Mater. Today Proc. 5,6376-6380. (doi:10.1016/j.matpr.2017.12.248)
7. Saleh TA. 2020 Nanomaterials: classification, properties, and environmental toxicities. Environ. Technoi. Innov. 20,101067. (doi:10.1016/j.eti. 2020.101067)
8. Neupane B, Zhao L, Wang G. 2013 Up-conversion luminescence of gold nanospheres when excited at nonsurface plasmon resonance wavelength by a continuous wave laser. Nano Lett. 13,4087-4092. (doi:10.1021/nl401505p)
9. Jana NR, Gearheart L, Murphy CJ. 2001 Wet chemical synthesis of high aspect ratio cylindrical gold nanorods J. Phys. Chem. В105,4065-4067. (doi:10.1021/jp0107964)
10. Li G, Jin R. 2013 Atomically precise gold nanoclusters as new model catalysts. Acc Chern. Res. 46,1749-1758. (doi:10.1021 /ar300213z)
11. Li H, Kang Z, Liu Y, Lee ST. 2012 Carbon nanodots: synthesis, propertiesand applications J. Wer. Chem. 22,24230. (doi:10.1039/c2jm34690g)
12. Golberg D, Bando Y, Huang Y, Terao T, Mitome M, Tang C, Zhi C. 2010 Boron nitride nanotubes and nanosheets. ACS Nano 4,2979-2993. (doi: 10.1021/nn1006495)
13. Murphy CJ. 2002 Nanocubes and Nanoboxes. Science 298,2139-2141. (d o i : 10.1126/science.1080007)
14. Fytianos G, Rahdar A, Kyzas GZ. 2020 Nanomaterials in Cosmetics: Recent Updates. Nanomaterials (Basel) 10,979. (doi:10.3390/nano10050979)
15. Augustine R, Hasan A. 2020 Emerging applications of biocompatible phytosynthesized metal/metal oxide nanoparticles in healthcare. J. Drug Deliv. Sei. Technoi. 56,101516. (doi:10.1016/j.jddst.2020.101516)
16. Sakthi Devi R, Girigoswami A, Siddharth M, Girigoswami K. 2022 Applications of gold and silver nanoparticles in theranostics. Appl. Biochem. Biotechnol. 194,4187-4219. (doi:10.1007/s12010-022-03963-z)
17. Singh NA. Nanoscience in food and agriculture 1. (eds S Ranjan, N Dasgupta, E Lichtfouse), Cham: Springer International Publishing.
18. Javed R, Zia M, Naz S, Aisida SO, Ain NU, Ao Q. 2020 Role of capping agents in the application of nanoparticles in biomedicine and environmental remediation: recent trends and future prospects. J. Nanobiotechnol. 18,172. (doi:10.1186/s12951 -020-00704-4)
19. Jamkhande PG, Ghule NW, Barner AH, Kalaskar MG. 2019 Metal nanoparticles synthesis: an overview on methods of preparation, advantages and disadvantages, and applications. 7. Drug Deliv. Sei. Technoi. 53,101174. (doi:10.1016/j.jddst.2O19.101174)
20. Ijaz M, Zafar M, Iqbal T. 2021 Green synthesis of silver nanoparticles by using various extracts: a review. Inorg. Nano-Met. Chern. 51,744-755. (d o i : 10.1080/24701556.2020.1808680)
21. Adhikari A, Lamichhane L, Adhikari A, Gyawali G, Acharya D, Barai ER, Chhetri К. 2022 Green synthesis of silver nanoparticles using Artemisia vulgaris extract and its application toward catalytic and metal-sensing activity. Inorganics 10,113. (doi:10.3390/inorganics10080113)
22. Li S, Shen Y, Xie A, Yu X, Qiu L, Zhang L, Zhang Q. 2007 Green synthesis of silver nanoparticles using Capsicum annuum L. extract. Green Chern. 9, 852. (doi:10.1039/b615357g)
23. Garibo D etai. 2020 Green synthesis of silver nanoparticles using Lysiloma acapulcensis exhibit high-antimicrobial activity. Sci. Rep. 10,12805. (doi:10.1038/S41598-020-69606-7)
24. Bar H, Bhui DK, Sahoo GP, Sarkar P, Pyne S, Misra A. 2009 Green synthesis of silver nanoparticles using seed extract oíJatropha curcas. Colloids Surf. Physicochem. Eng. Asp. 348,212-216. (doi: 10.1016/j.colsurfa.2009.07.021 )
25. Silva LP, Bonatto CC, Polez VLP. 2016 Green synthesis of metal nanoparticles by fungi: Current trends and challenges. In: Prasad, R. (eds) Advances and Applications Through Fungal Nanobiotechnology. Cham: Springer.
26. Elsakhawy T, D. Omara AE, Abowaly M, El-Ramady H, Badgar K, Llanaj X, Torhos G, Hajdú P, Prokisch J. 2022 Green synthesis of nanoparticles by mushrooms: a crucial dimension for sustainable soil management. Sustainability 14,4328. (doi: 10.3390/su 14074328)
27. Chandra A, Bhattarai A, Yadav AK, Adhikari J, Singh M, Giri B. 2020 Green synthesis of silver nanoparticles using tea leaves from three different elevations. ChemistrySelect. 5,4239-4246. (doi:10.1002/slct.201904826)
28. Boruah JS, Devi C, Hazarika U, Bhaskar Reddy PV, Chowdhury D, Barthakur M, Kalita P. 2021 Green synthesis of gold nanoparticles using an antiepileptic plant extract: in vitro biological and photo-catalytic activities. RSCAdv. 11,28029-28041. (doi:10.1039/d1ra02669k)
29. Mat Yusuf SNA, Che Mood CNA, Ahmad NH, Sandai D, Lee CK, Lim V. 2020 Optimization of biogenic synthesis of silver nanoparticles from flavonoid-rich Clinacanthus nutans leaf and stem aqueous extracts. R. Soc. Open Sei. 7,200065. (doi:10.1098/rsos.200065)
30. Chokkareddy R, Redhi GG, Kanchi S, Ahmed S. 2018 Green synthesis of metal nanoparticles and its reaction mechanisms. In Green Metal Nanoparticles pp. 113-139, Beverly, MA: Scrivener Publishing LLC. (doi:%2010.1002/9781119418900)
31. Talarska P, Boruczkowski M, Żurawski J. 2021 Current knowledge of silver and gold nanoparticles in laboratory research-application, toxicity, cellular uptake. Nanomaterials 11,2454. (doi:10.3390/nano11092454)
32. Velmurugan P etai. 2014 Green synthesis of silver and gold nanoparticles using Zingiber officinale root extract and antibacterial activity of silver nanoparticles against food pathogens. Bioprocess. Biosyst. Eng. 37,1935-1943. (doi:10.1007/s00449-014-1169-6)
33. Mukherjee A, Sarkar D, Sasmai S. 2021 A review of green synthesis of metal nanoparticles using algae. Front. Microbiol. 12, 693899. (doi:10. 3389/fmicb.2021.693899)
34. Pariai D, Patra HK, Dasgupta AK, Pal R. 2012 Screening of different algae for green synthesis of gold nanoparticles. Eur. J. Phycol. 47,22-29. (doi: 10.1080/09670262.2011.653406)
35. Aygün A, Özdemir S, Gülcan M, Cellat К, Şen F. 2020 Synthesis and characterization of Reishi mushroom-mediated green synthesis of silver nanoparticles for the biochemical applications J. Pharm. Biomed. Anal. 178,112970. (doi:10.1016/j.jpba.2019.112970)
36. Owaid MN. 2019 Green synthesis of silver nanoparticles by Pleurotos (oyster mushroom) and their bioactivity: review. Environ. Nanotechnol. Monit. Manag. 12,100256. (doi:10.1016/j.enmm.2019.100256)
37. Chagnon C, Simard M, Boudreau S. 2021 Patterns and determinants of lichen abundance and diversity across a subarctic to arctic latitudinal gradienti Biogeogr. 48,2742-2754. (doi:10.1111/jbi.14233)
38. Yang MX, Devkota S, Wang LS, Scheidegger C. 2021 Ethnolichenology-the use of lichens in the Himalayas and Southwestern parts of China. Diversity. 13,330. (doi:10.3390/d 13070330)
39. Conti ME, Cecchetti G. 2001 Biological monitoring: lichens as bioindicators of air pollution assessment-a review. Environ. Pollut. 114,471- 492. (d o i : 10.1016/s0269-7491 (00)00224-4)
40. Din LB, Mie R, Samsudin MW, Ahmad A, Ibrahim N. 2015 Biomimetic synthesis of silver nanoparticles using the lichen Ramalina dumeticola and the antibacterial activity. Malays. J. Anal. Sei. 19,369-376.
41. Mie R, Samsudin MW, Din LB, Ahmad A. Applied mechanics and materials. Zürich: Trans Tech Publication.
42. Çıplak Z, Gökalp C, Getiren В, Yıldız A, Yıldız N. 2018 Catalytic performance of Ag, Au and Ag-Au nanoparticles synthesized by lichen extract. Green Process. Synth. 7,433-440. (doi:10.1515/gps-2017-0074)
43. Rai H, Gupta RK. 2019 Biogenic fabrication, characterization, and assessment of antibacterial activity of silver nanoparticles of a high altitude Himalayan lichen - Cladonia rangiferina (L.) Weber ex RH. Wigg. Trop. Plant Res. 6,293-298. (doi:10.22271/tpr.2019.v6.i2.037)
44. Rattan R, Shukla S, Sharma B, Bhat M. 2021 A mini-review on lichen-based nanoparticles and their applications as antimicrobial agents. Front. Microbiol. 12,633090. (doi:10.3389/fmicb.2021.633090)
45. Siddiqi KS, Rashid M, Rahman A, Husen A, Rehman S. 2018 Biogenic fabrication and characterization of silver nanoparticles using aqueous-ethanolic extract of lichen (Usnea longissima) and their antimicrobial activity. Biomater. Res. 22,23. (doi:10.1186/s40824-018-0135-9)
46. Prabhu SS, Ramanujam JR, Sudha S. 2019 Antibacterial activity of silver nanoparticles synthesized by using lichens Heterodermia boryi and Parmotremastuppeum. Int. J. Pharm. Biol. Sci. 9,1397-1402. (doi:10.21276/ijpbs.2O19.9.2.167)
47. Jain S, Mehata MS. 2017 Medicinal plant leaf extract and pure flavonoid mediated green synthesis of silver nanoparticles and their enhanced antibacterial property. Sci. Rep. 7,15867. (doi:10.1038/s41598-017-15724-8)
48. Goudarzi M, Mir N, Mousavi-Kamazani M, Bagheri S, Sa I a vati-N iasa ri M. 2016 Biosynthesis and characterization of silver nanoparticles prepared from two novel natural precursors by facile thermal decomposition methods. Sei. Rep. 6,32539. (doi:10.1038/srep32539)
49. Velmurugan P, Shim J, Kamala-Kannan S, Lee KJ, Oh BT, Balachandar V, Oh ВТ. 2011 Crystallization of silver through reduction process using Elaeisguineensis biosolid extract. Biotechnol. Prog. 27,273-279. (doi:10.1002/btpr.511)
50. Patil MP, Singh RD, Koli PB, Patil KT, Jagdale BS, Tipare AR, Kim GD. 2018 Antibacterial potential of silver nanoparticles synthesized using Madhuca longifolia flower extract as a green resource. Microb. Pathog. 121,184-189. (doi:10.1016/j.micpath.2O18.05.040)
51. Kumar I, Gangwar C, Yaseen B, Pandey PK, Mishra SK, Naik RM. 2022 Kinetic and mechanistic studies of the formation of silver nanoparticles by nicotinamide as a reducing agent. TICS Omega 7,13778-13788. (doi:10.1021/acsomega.2c00046)
52. Alzoubi FY, Bidier SA. 2013 Characterization and aggregation of silver nanoparticles dispersed in an aqueous solution. Chin. J. Phys. 51, 378-387. (doi:10.6122/CJP.51.378)
53. Dhoondia ZH, Chakraborty H. 2012 Lactobacillus mediated synthesis of silver oxide nanoparticles. Nanomater. Nanotechnol. 2,15. (doi:10.5772/ 55741)
54. Patil MP, Palma J, Simeon NC, Jin X, Liu X, Ngabire D, Kim NH, Tarte NH, Kim GD. 2017 Sasa borealis leaf extract-mediated green synthesis of silver-silver chloride nanoparticles and their antibacterial and anticancer activities. New J. Chern. 41,1363-1371. (doi: 10.1039/C6NJ03454C)
55. Langford JI, Wilson AJC. 1978 Scherrer after sixty years: a survey and some new results in the determination of crystallite size. J. Appl. Crystallogr.U, 102-113. (doi:10.1107/S0021889878012844)
56. Guo Y, Wang Z, Qu W, Shao H, Jiang X. 2011 Colorimetric detection of mercury, lead and copper ions simultaneously using protein-functionalized gold nanoparticles. Biosens. Bioelectron. 26,4064-4069. (doi:10.1016/j.bios.2011.03.033)
57. Katsikas L, Gutiérrez M, Henglein A. 1996 Bimetallic colloids: silver and mercury. J. Phys. Chem. 100,11203-11206. (doi:10.1021/jp960357i)
58. Neupane B, Sharma N, Gautam S, Adhikari A. 2024 Data from: Lichen biomass for green synthesis of silver nanocolloids. Dryad Digital Repository. (doi:10.5061 /dryad.wstqjq2t7)
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Abstract
Lichen is one of the most abundant non-vascular biomasses; however, a systematic study on the application of biomass in nanomaterial synthesis is very limited. In this study an aqueous lichen extract was obtained from Hypotrachyna cirrhata, one of the most abundant Himalayan lichen biomasses, using a simple cold percolation method. The effects of extract-to-silver nitrate mixing ratio, pH and waiting time on the growth and stability of nanoparticles were systematically explored. The rate constant for bio-reduction was found to be 5.3 x 10-3 min-1. Transmission electron microscopy showed a narrow particle size distribution with a mean particle size of 11.1 ± 3.6 nm (и = 200). The X-ray diffraction and selected area electron diffraction techniques confirmed the formation of cubic crystals. The synthesized colloidal solution showed excellent response to Hg2+ and Cu2+ ions in spiked water samples. The limit of detection and calibration sensitivity for Hg2+ and Cu2+ ions were found to be 1 and 5 mg 1-1 and 2.9 x 10-3 and 1.6 x 10-3 units ppm-1, respectively. These findings suggested that spherical silver nanoparticles with a narrow particle size distribution can be synthesized on a laboratory scale using an aqueous H. cirrhata lichen extract, and the colloidal solution can be used for the detection of selected heavy metals in water samples.
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Details
1 Central Department of Chemistry, Tribhuvan University, Kirtipur, Kathmandu 44613, Nepal
2 Department of Chemistry, Tri-Chandra Multiple Campus, Tribhuvan University, Kathmandu 44605, Nepal
3 Central Department of Chemistry, Tribhuvan University, Kirtipur, Kathmandu 44613, Nepal 0000-0003-0731-2552