Biomedical and photocatalytic applications of biosynthesized silver nanoparticles: Ecotoxicology study of brilliant green dye and its mechanistic degradation pathways

Article abstract of DOI:10.1016/j.molliq.2020.114114

The preparation of nanoparticles from biological materials is an economic and environmentally friendly strategy with several advantages. The current study is focused to synthesize silver nanoparticles using Petroselinum crispum plant extract. Various char

Full text of DOI:10.1016/j.molliq.2020.114114

Journal of Molecular Liquids 319 (2020) 114114
Contents lists available at ScienceDirect
Journal of Molecular Liquids
journal homepage: www.elsevier.com/locate/molliq
Biomedical and photocatalytic applications of biosynthesized silver
nanoparticles: Ecotoxicology study of brilliant green dye and its
mechanistic degradation pathways
a
c
b
a
Zia Ul Haq Khan a,b, , Noor Samad Shah , Jibran Iqbal , Arif Ullah Khan , Muhammad Imran ,
Saad M. Alshehri e, Nawshad Muhammad d, Murtaza Sayed f, Naveed Ahmad a, Amina Kousar a,
Munazza Ashfaq a, Fares Howari c, Kamran Tahir g
⁎
a
Department of Environmental Sciences, COMSATS University Islamabad, Vehari Campus, 61100, Pakistan
Beijing Advanced Innovation Centre for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China
College of Natural and Health Sciences, Zayed University, P.O. Box 144534, Abu Dhabi, United Arab Emirates
Interdisciplinary Research Centre in Biomedical Materials, COMSATS University Islamabad, Lahore Campus, 54000, Pakistan
Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
Radiation Chemistry Laboratory, National Centre of Excellence in Physical Chemistry, University of Peshawar, Peshawar 25120, Pakistan
b
c
d
e
f
g
Institute of Chemical Science GU DIK, Pakistan
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 12 May 2020
Received in revised form 7 August 2020
Accepted 20 August 2020
Available online 22 August 2020
The preparation of nanoparticles from biological materials is an economic and environmentally friendly strategy
with several advantages. The current study is focused to synthesize silver nanoparticles using Petroselinum
crispum plant extract. Various characteristics of biologically synthesized AgNPs were determined with UV–
Visible (UV/Vis) Spectroscopy, X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR) Spectroscopy, and
High-Resolution Transmission Electron Microscopy (HRTEM). The plasmonic resonance peak at 425 nm ensured
the formation of AgNPs. The FTIR analysis showed that the as-synthesized particles contain alcoholic and poly-
phenolic constituents, which are responsible for their capping and reduction. The HRTEM results revealed spher-
ical shape of AgNPs with size ranging from 25 to 90 nm. The as-synthesized particles demonstrated excellent
antibacterial properties against Gram positive and Gram-negative bacteria. The antioxidant applications of the
particles were determined with 2,2-diphenyle-1-picrylhydrazyl (DPPH). Moreover, the photocatalytic applica-
tion of the synthesized AgNPs was evaluated for brilliant green dye (BG). The results demonstrated high degra-
dation of BG due to small size and well-dispersed nature of AgNPs. Degradation products of BG were identified to
suggest degradation pathways. The eco-toxicity of the BG and constituents derived from the dye were studied
with Ecological Structure Activity Relationship (ECOSAR) software.
Keywords:
Petroselinum crispum
AgNPs
Antibacterial properties
Photocatalytic activities
Brilliant green
© 2020 Elsevier B.V. All rights reserved.
1. Introduction
the crystalline center of the AgNPs result into their toxicity [7]. The im-
portance of catalytic materials is constantly increasing due to increasing
The silver nanoparticles (AgNPs) are widely used in a number of
products such as food storage containers, textiles and personal care
products (PCP) [1]. In daily life, demand of AgNPs is growing owing to
their unique physiochemical characteristics in comparison to their
bulk counterparts [2,3]. In this modern era of material chemistry,
these metallic nanoparticles have more attraction because of their
good electrical, optical and catalytic potential [4]. The NPs are utilized
for various biomedical purposes in combination with biomolecules
such as ligands and antibodies etc. [5,6]. The silver ions released from
need for energy production, environmental remediation as well as re-
sources concerns [8,9]. In past few years, the synthesis of nanoparticles
with biological materials has gained significant attention due to its sim-
ple, eco-friendly, cost effective and renewability features [10–15]. The
most frequently adopted strategy for the synthesis of NPs is chemical
synthesis [16,17] and the majority of chemicals used for the synthesis
of nanomaterials are toxic and inappropriate for various applications.
The form, size and distribution of the NPs are crucial for physical, chem-
ical and biological characteristics of NPs. Consequently, the chemical
techniques prove advantageous when producing NPs in large amounts
in a comparatively short time period with a command on the particles
size distribution [18]. Several studies have reported the use of fungi
[19], bacteria [20–21], plants, algae [22] and phytochemical compounds
⁎
Corresponding author at: Department of Environmental Sciences, COMSATS
University Islamabad, Vehari Campus, 61100, Pakistan.
E-mail address: ziaulhaqkhan11@gmail.com (Z.U.H. Khan).
https://doi.org/10.1016/j.molliq.2020.114114
0167-7322/© 2020 Elsevier B.V. All rights reserved.

2
Z.U.H. Khan et al. / Journal of Molecular Liquids 319 (2020) 114114
[22–27] for the biological synthesis of nanoparticles. The metal nanopar-
ticles are mostly utilized in various applications e.g. electronics, material
science, cosmetics, biomedicine [28,29], catalysis [30], pharmaceuticals,
and environmental analysis [31] due to their highly reactive nature,
high volume ratio and optical properties [32]. Brilliant green is
triphenylmethane-based dye which has a perceptive application in
leather, textile as well as in biotic industries [33,34] but BG polluted
water has hostile impact on human and can induce health issue like
lungs, kidney [35–40]. Dyes are carbon-based compounds of various
types e.g. anionic, cationic, disperse neutral etc. [41,42]. Therefore, it is
important to sequester the dyes from contaminated water. Therefore,
photodegradation under visible light has evolved as an economic
method for the decontamination of BG from water [33,34,43]. To the
best of our knowledge, the Petroselinum crispum biomass and its extract
has not been explored so far for the biological synthesis of AgNPs. There-
fore, in the present study AgNPs were synthesized through a green pro-
cess by using Petroselinum crispum extract. The Petroselinum crispum
plant contains a wide range of active ingredients including alcoholic
compounds, phenolic ester, flavonoids and volatile constituents
[44,45]. The potential of synthesized AgNPs were evaluated for photocat-
alytic, antioxidant and antibacterial activity.
2.5. Minimum inhibitory concentration
The lowest effective dose of AgNPs was estimated by using the min-
imum inhibitory concentration technique. Approximately 1.0 ml of
three microbial mixtures were mixed with different concentrations of
AgNPs in sterilized tubes. The test tubes were shaken for 24 h in an in-
cubator at 37 °C. The test tubes containing growth media and microbes
were considered as a control.
2.6. Antioxidant activity of silver nanoparticles
The 2, 2-diphenyl-1-picrylhydrazyl (DDPH) free radical scavenger
experiment was used to evaluate the antioxidant activity of AgNPs
[48]. Various concentrations of AgNPs (0.01, 0.062, 0.125, 0.25, 0.5.
and 1.0 mg ml−1) were used and placed in dark for 20 min to 40 min.
The DPPH and methanol without sample were considered as a control
and Vitamin C was taken as a reference. The absorbance was measured
with UV/Vis spectrometer and inhibition (I%) was calculated with
Eq. (1).
ꢀ
ꢁ
Ac−At
Ac
Ið%Þ ¼
ꢀ 100
ð1Þ
2. Materials and methods
where, Ac and At is the absorbance (−) of control and absorbance (−) of
sample at time t, respectively.
2.1. Preparation of Petroselinum crispum extract
2.7. Photocatalytic activity
The biomass of Petroselinum crispum (common name parsley) was
taken from a local field and rinsed with distilled water to get rid of the
dust and adhered debris material. The Petroselinum crispum biomass
was dried under shade and crushed to fine particles. About 50 g of
dried plant biomass was soaked in 200 ml distilled water at room tem-
perature for 24 h with continuous stirring followed by filtration to ob-
tain plant extract. The obtained extract was saved and used for the
synthesis of AgNPs.
The photodegradation efficiency of the prepared silver nanoparticles
was assessed by degrading brilliant green dye (BG) with visible light ir-
radiation. Lower pressure (15 W) Mercury lamp (LP Hg lamps,
Coleparmer) with monochromatic emission at 254 nm was used as a
visible light source. The dose of AgNPs (10 mg) was added in 60 ml of
BG solution with concentration of 15 mg/L. The photodegradation of
brilliant green were carried out at 25 °C with the projection of low-
pressure lamp (LP, 15 W) as visible source. The light was placed at a dis-
tance 8–10 cm from dye solution containing AgNPs (150 mL beaker).
Prior to photodegradation, the BG and AgNPs mixture was thoroughly
stirred for 10–15 min with a magnetic stirrer to get equilibrium. To in-
vestigate the photodegradation potential of the AgNPs, BG samples
(5 ml) were taken at every 5 min and absorbance of the samples mea-
sured using UV–Visible spectrophotometer (Perkin Elmr). In order to
calculate the self-degradation of dye, blank test under the visible light
was also run and its absorbance was measured. The degradation % of
BG was determined with Eq. (2).
2.2. Synthesis of silver nanoparticles
The Petroselinum crispum plant extract contains phenolic constitu-
ents, which benefit in the reduction of metallic ions during nanoparti-
cles preparation. To prepare AgNPs, 10 ml of plant extract was mixed
dropwise into the 50 mL of 3 × 10−3 M aqueous solution of AgNO3.
UV/Vis spectroscopy was used to find the plasmonic peak for the prep-
aration of AgNPs. The colloidal solution was centrifuged at 5000 rpm for
10 min to segregate AgNPs and finally dried under vacuum.
ꢀ
ꢁ
2.3. Characterization
Ac−At
Ac
Degradationð%Þ ¼
ꢀ 100
ð2Þ
The biosynthesis of AgNPs with Petroselinum crispum extract was
confirmed from the absorbance measured in the wavelength range of
200–800 nm using UV/Vis spectrophotometer (Perkin Elmr). The XRD
(Rigaku D/Max 2500 VBZ/PC) analysis was performed at operating Volt-
age 30 kV and 15 mA in the range of 20–80°. To determine the nature
and size of the particles, HRTEM (JEM3010) analysis was performed at
microscope voltage of 200 kV. FT-IR (ABB MB 3000) analysis was con-
In Eq. (2), Ac and At represent initial absorbance of BG solution and
its absorbance at time t, respectively.
2.8. Impact of coexisting ions on BG sequestration
In order to calculate the effect of different competing ions in water
on BG removal, two groundwater samples were collected from Vehari
City, Pakistan. The electrical conductivity [2], total dissolved salts
(TDS), pH, Na, K, Ca, CO3, HCO3, Cl were measured in water samples
and the results are shown in Table 1. The EC (dS/m) and TDS (mg/L)
ducted in the wavenumber range of 400–4000 cm−1
.
2.4. Antibacterial activity of AgNPs
The antimicrobial activity of AgNPs was estimated with agar well
diffusion method [46]. Ofloxacin was taken as a standard and inocula
of precise amounts of bacterium were streaked on Muller Hinton agar
plates. The wells (6 mm in diameter) on agar plates were made using
sterilized cork borer and 1 mg of AgNPs was dissolved in 1 mL distilled
water and then 50 μl of prepared AgNPs were added in one well. The
plate was nurtured for 24 h at 37 °C and diameter (mm) of inhibition
zones was measured [47].
Table 1
Characterizations of GW used to evaluate the impact of compacting ions.
Sample
pH
EC
TDS
Mg
Na
K
Ca
CO3
HCO3
Cl
GW1
GW2
7.8
7.9
1.14 570
0.62 300
20
20
113.5
18.8
5.6 45.6
4.5 12.3
60
60
305
427
424.8
566.4

Z.U.H. Khan et al. / Journal of Molecular Liquids 319 (2020) 114114
3
were measured by EC meter and TDS meter, respectively. The concen-
trations (mg/L) of Na, K and Ca were measured with flame photometer
while concentration of CO3, HCO3, Cl were estimated with titration
method following standard methods [49]. The impact of competing
ions on BG removal was evaluated at 15 mg BG/L, dose of AgNPs
(10 mg/60 ml), ambient temperature and pH-8.
2.9. Eco-toxicity
The toxicity of BG and its by-products was evaluated with a toxicity
predictive program Ecological Structure Activity Relationship (ECOSAR)
[30]. Three different aquatic organisms (fish, daphnia and green algae)
were used to evaluate the toxicity of BG and its degradation products
with reference to their LC50 and EC50. LC50 depicts the level of a contam-
inant that kills 50% for fish and daphnia after 96 h and 48 h, respectively.
While EC50 describes the contaminant concentration which resulted in a
50% reduction in growth of green algae after a contact time of 96 h.
3. Results and discussion
3.1. UV/Vis spectroscopy
The UV/Vis spectroscopy was employed in the range of 200–800 nm
to scan for electronic transition. Surface plasmonic resonance (SPR) of
AgNPs exhibited maximum absorbance 425 nm (Fig. 1). By absorbing
UV light non-bonding electrons jump from the higher occupied molec-
ular orbital (HOMO) to lowest unoccupied molecular orbital (LUMO)
and the difference in energy between E1 and E2 depends on the amount
of energy absorbed by the emitted electron (ΔE = E1-E2). The size and
particles' size distribution are dependent on the plant extract [50]. The
phenolic and alcoholic compounds help in the reduction of metal ions
to zero valence (Ag°). Scheme 1 shows the zero valent Ag° formation
by photochemical reduction of Ag ions [51–53].
3.2. X-ray diffraction (XRD) pattern
Scheme 1. Proposed mechanism of Ag reduction into Ag° using Petroselinum crispum as a
reducing agent.
The crystalline phase analysis of the synthesized AgNPs was deter-
mined by X-ray diffraction (XRD) (Fig. 2). The XRD peaks were observed
at 38.21°, 44.30°, 64.52° and 77.47° (2θ values) which correspond to 111,
200, 220 and 311 lattice planes of face centered cubic silver (JCPDS file
04-0784) [8]. The peak intensity at 111 is greater than the other planes.
These 111 facets were found to be the most reactive due to the high
atomic density. Analogous findings were reported previously in the
plant extract mediated preparation of silver and gold NPs [53].
3.3. FT-IR spectroscopy
The FT-IR spectrum of biosynthesized AgNPs is shown in Fig. 3. The
FTIR results show that absorption at 3375 cm−1 indicates stretching vi-
bration of hydroxyl group and absorption at 2305 cm−1 belongs to
stretching of aromatic structure (-CH2) with weak appearance. Absorp-
tion of C-OH has been observed at 1424 cm−1 and absorption peak at
765 cm−1 shows the C-O-C group [55–57]. The hydroxyl groups in
plant extract are due to the presence of several phenolic molecules
which help in the stabilization of synthesized AgNPs as can be seen in
Fig. 3b. The results suggested that Petroselinum crispum plant extract
contains phenolic compounds which contribute to reduce and stabilize
the formation of AgNPs as shown in the following reaction (A) [58,59].
Agþ þ 3R þ 3OH−→Ag0 þ 3RO− þ 3Hþ
ðAÞ
3.4. High-resolution transmission electron microscopy (HRTEM) analysis
The HRTEM was used to evaluate the distribution, size, nature and
morphology of the synthesized AgNPs. The results revealed that the
morphology of AgNPs is spherical, and particles are well dispersed and
scattered (Fig. 4). The particle's size obtained from HRTEM images
ranged from 25 nm to 90 nm. The smaller sized particles with larger sur-
face area show high photocatalytic and biological activities [60–62].
Fig. 1. UV/Vis spectrum of AgNPs.

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Z.U.H. Khan et al. / Journal of Molecular Liquids 319 (2020) 114114
Fig. 2. XRD spectrum of AgNPs.
With lower doses of plant extract, metal nuclei formation decreases and
fewer nuclei are generated which may lead to larger particle sizes.
with characteristics given in Table 1. The results revealed that GW1
showed 3% less removal of BG compared to GW2. The decline in BG re-
moval in GW1 is attributed to higher concentration of competing ions
(Na, K and Ca) in GW1 compared to GW2. The results displayed that
competing ions in water showed decline in intensity of absorption
which shows the photodegradation of BG dye. The photodegradation
was high because of three reasons; (1) the light absorption capacity of
AgNPs, (2) spherical and small particles size of AgNPs with larger sur-
face area and (3) and no aggregation of particles [65]. The literature
also shows that catalytic activity is highly dependent on morphology,
size and crystal structure of nanoparticles [66,67]. Scheme 2 shows
the suggested mechanism for the photocatalytic decomposition of BG
by AgNPs [68]. Scheme 2 illustrates that when UV light strikes the elec-
trons of AgNPs, energy is gained which results in the emission of elec-
trons from the outer shell as shown in Fig. 6. These emitted electrons
are used for the production of hydroxyl radicals which correspond to
the degradation of BG. The mechanism shows that light contributes
3.5. Photo degradation of brilliant green (BG) dye
Various toxic compounds such as dyes and organic compounds are
released from industries and exhibit harmful impact on human, plants
and animals' health. The BG dye which is a stable organic compound
with an aromatic structure is light and heat sensitive compound as
shown in Fig. 5 [64]. Experiments on the degradation of BG were con-
ducted to investigate the photo-catalytic potential of biosynthesized
AgNPs. The BG removal was investigated at 10 mg dose of AgNPs in
60 mL of dye solution 15 mg/mL at ambient temperature (25 °C). The
degradation peak of BG appeared at 624 nm. The impact of contact
time was evaluated for different time intervals as given in Fig. 6(a, b).
The impact of different competing ions in water on BG removal was
also evaluated by taking two groundwater samples (GW1 and GW2)
Fig. 3. FT-IR Spectrum of AgNPs.

Z.U.H. Khan et al. / Journal of Molecular Liquids 319 (2020) 114114
5
Fig. 4. HRTEM of the AgNPs.
significantly in the decomposition of BG. Reactive oxygen species such
as •OH as well as O2 radicals are created by photo-electrons which are
involved in the photo degradation of the BG in water [28,69]. It is also
proposed that the photocatalytic degradation reaction occurs heteroge-
neously by creating positive holes (h+VB) in the conduction band catalyst
through irradiation. In this process, generation of •H and •OH occurs by
the reaction of positive hole with water and degradation process starts
by the highly energetic •OH reaction with BG molecules [30]. The
photogenerated electron reacts with electron acceptor e.g. O2 absorbed
on the metal surface or were oxidized to the end products due to strong
oxidizing nature of •OH radicals [70]. The substrate which is unreactive
with •OH radical was degraded due to the catalytic role of AgNPs [71,72].
It is suggested that adsorbed-dye-molecules' excitation occurs due to
the light which causes a singlet or triplet state successively followed
from the excited molecules of BD onto the conduction band of AgNPs.
Fig. 5. Resonating structure of brilliant green dye.
Fig. 6. Photo-degradation of brilliant green (a) effect of light (b) effect of catalyst.

6
Z.U.H. Khan et al. / Journal of Molecular Liquids 319 (2020) 114114
Scheme 2. Proposed degradation mechanism of brilliant green.
Due to this reason, transformation of dye to cationic radical was lia-
ble for the degradation. Oxidation reaction occurs by the interac-
tion of dye species with •OH radical or by the interaction with
O•2-, HO•2 or hydroxy radical [73]. The absorption intensity de-
creased with the increase in time which showed the degradation
of BG dye. About 80% of the dye was degraded within 20 min at
pH 7.9.
3.6. Antibacterial activity
The synthesized AgNPs were evaluated for their antibacterial prop-
erties. The particles showed good activities against S. aureus and E.
coli. 18 0.5 mm and 14 0.8 mm inhibition zone diameter, respec-
tively compared with standard drug which was 18.5
0.6 mm and
12 0.4 mm as shown in Table 2. The AgNPs penetrated the cell wall
and ultimately caused cell death. Generally, through multiple mecha-
nisms, NPs attack bacteria cells (Fig. 7). The results revealed that due
to small and spherical size, the particles showed significant antibacterial
activity.
Ag∘ þ hvðUVÞ→AgNPsðeCB þ hVBÞþ
ð3Þ
ð4Þ
ð5Þ
ð6Þ
ð7Þ
ð8Þ
ð9Þ
−
∘
∘
AgðhUV Þ þ H2O→Ag∘ þ H þ OH
•−
−
AgNPSðeCB Þ þ O2→AgNPs þ O2
Table 2
•−
•
O2 þ Hþ→HO2
Anti-bacterial activity (zone of inhibition).
Microorganism
Zone of inhibition in (mm)
AgNPs
Dye þ OH•→Degradation−products
Ref
þ
Dye þ hVB →Oxidation−prodcuts
S. aureus
E. coli
18( 0.5)
14( 0.8)
18.5( 0.6)
12( 0.4)
−
Dye þ eCB →Reduction−products
mm = millimeter, references = ofloxacin, 25–30 °C.

Z.U.H. Khan et al. / Journal of Molecular Liquids 319 (2020) 114114
7
Fig. 7. Proposed antibacterial mechanism using AgNPs.
Fig. 8. Antioxidant activity of AgNPs.
3.7. Minimum inhibitory concentration
OH radical prefers to occupy atoms having greater value of (FED2-
HOMO + FED2LUMO) [33,74]. During the degradation process the H-
atoms are distracted by OH from the atom with higher value of point
charge [33,34,74]. The products formation of reactive radical might be
used for explaining the routes involved in the formation of detected
BG DPs. The development of DP1(Scheme 2), resulted the abstraction
of H-atom by •OH. The •OH radical play important role in the removal
of R-(alkyle) group and resulted DP2. DP3, photooxidation occur and
the -methylene (enol) converted to -CO2H which caused decarboxilation
(Scheme 2). Hydroxy radical abstract of H-atom occurred from N-atom
resulted DP5 (Scheme 2). In the presence of reactive •OH, substitution re-
action occur and resulted epoxide in DP6. Because of higher vale (FED2-
HOMO + FED2LUMO) •OH radical abstracted electron and another
reactive species diol created in DP6 (Scheme 2). The organic DPs were
formed from electron transfer oxidation and bond cleavage. The DP7,
the NH2 undergo a series of substation reaction and converted to DP8 as
shown in scheme while ETR (electron transfer reaction) with •OH to the
biphenyl group, undergo band cleavage and formed DP9 as shown in
scheme 2. In DP9 FGI occurred due to the involvement of OH and series
of chemical reaction occure and finally DP9 is converted to DP 10. The
•OH radical H-atom from N-atom resulted DP11. During phooxidation
process, OH abstracted electron from -C-OH and formed DP12. Functional
group Interconversion (FGI) take place because of photooxidation (•OH)
and resulted DP13. The •OH abstracted of methyl H-atom (-CH2-) and
due FGI decarboxylation (CO2) and series of reaction involved resulted
the formation of DP13-D17 as shown in scheme 2. The Pathway -II is
followed by OH radical track at the N-attached to the small moiety bear-
ing NH2, undergo electron transfer and bond cleavage reactions and form
products DP18-DP20 through of loss of nitrogen group. The substitution
reaction occurs in DP20 and DP21 and resulted DP22 [43].
The MIC is the lowest dose of AgNPs which prevents the growth of
particular germs. Dilute suspensions of AgNPs were positioned in an in-
cubator at various concentrations with bacterial strains of S. aureus, and
E. coli to examine the growth of the germs. The observed MIC of the mi-
crobes (S. aureus, and E. coli) was 120 μg and 235 μg after 24 h as shown
in Table 3.
3.8. Antioxidant activity of bio-synthesized AgNPs
It is reported that reducing agents have potential to stop ROS crea-
tion that makes them supreme to cure various malignant diseases.
2,2-diphenyl-1-picrylhydrazyl was used to estimate the antioxidant po-
tential with Vitamin C as reference. Due to its high stability, DPPH is usu-
ally used for the analysis of radical scavenging or hydrogen donating
capability of plant extracts and NPs. The DPPH has the potential to ac-
cept electron from AgNPs. The antioxidant potential given in Fig. 8
revealed that the scavenging effect of DPPH was enhanced as the
concentration of NPs increased and maximum scavenging was found
at the rate of 1 mg ml−1 (85%). The NPs reacted with peroxide and
prevented peroxide ion formation. Antioxidant properties are associ-
ated with electron donating potential of nanocrystals and collaboration
among AgNPs and DPPH free radical. The AgNPs have the ability to do-
nate electron and stabilize the peroxide to more stable products which
help in the termination of chain reactions thereby increasing antioxi-
dant activity at higher concentration of AgNPs.
3.9. Proposed degradation pathway
The •OH free radical caused chain reaction which makes the mecha-
nistic study of C-based compounds very complex by reactive radicals
and generally results into the formation of various group of dilapidation
by-products from organic contaminants. Therefore, the study of ele-
mentary reaction that comprises the production of a specific species
needs additional understanding with photo-lysis and isotope modeling
[33].
UPLC-MS/MS analysis of Aqueous Brilliant green solution treated
with UV/visible light and showed the formation 22 degradation prod-
ucts (DPs). It is confirmed that DPs formed during the degradation are
largely owing to the involvement of •OH. The •OH radical is active ion
and initiate the degradation process of brilliant green dye. The frontier
electron density of highest occupied molecular orbital (HOMO) and
lowest unoccupied molecular orbital (LUMO) is used to predict the ini-
tial active sites of the concern compound by •OH radical. It is found that
3.10. Ecotoxicity
The ECOSAR program was used to check the ecotoxicity of degraded
byproducts of BG towards three aquatic species (fish, Daphnia, and
green algae) and the results are presented in Table 4. As opposed to
the parent compounds, various degradation compounds indicated
more toxicity and toxic behavior for aquatic species such as fish, Daph-
nia, and green algae. Scheme 2 completely represents the destruction of
BG and its DPs [34,74].
Table 3
MIC of AgNPs of bacterial strain.
Bacterial strain
MIC
S. aureus
E. coli
120 μg
235 μg
μg = microgram, 25–30 °C, 20–24 h.

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Z.U.H. Khan et al. / Journal of Molecular Liquids 319 (2020) 114114
Table 4
Ecotoxicity of byproducts of brilliant green.
Fish
Daphnia Green
Fish LC50
(ChV)
Daphnia
Green Algae
(ChV)
Compound
BG
(LC50)
(LC50)
Algae
(EC50)
39.561*
LC50 (ChV)
65.072*
39.654*
12.126
46667.770
0.017
82.297
7771.125
0.012
0.012
0.002
0.581
2.225
0.661
0.511
0.044
1.863
1.014
20.804
68.937
0.020
1.692
1.770
0.471
0.531
35.260
0.605
0.029*
36.419 (H)
244.885 (NH)
2.851
DP1
3734.263 1899.599 898.174
DP2
3.349
1.896
1.896
0.019
1.580
12.782
3.478
2.689
0.811
9.010
4.474
157.779
1.348
DP3
3.349
1.348
0.017
2.851
DP4
0.098
0.006
0.0013
0.649
0.003
DP5
1.442
0.985
0.793
DP6
112.655
7.902
11.629
14.724
11.123
3.249
86.923
0.904
0.471
DP7
6.843
DP8
5.495
0.651
5.154
DP9
259.738
10.613
5.120
1.494
4.992
DP10
DP11
DP12
DP13
DP14
DP15
DP16
DP17
DP18
DP19
DP20
DP21
DP22
5.468
1.130
3.471
3.123
0.590
2.185
213.875
48.312
518.374
1.978
15.538
125.419
0.102
19.094
132.290
3.687
1300.781 730.075
19.446
9.078
38.351
0.553
0.546
343.67
0.609
3.181
1.403
7.819
9.295
0.414
1.643
234.885
1.867
0.406
5.088
1.005
3.390
44.824
0.917
3.605
21.188
0.069
0.075
0.889
0.208
0.170
136.170
0.967
106.678
0.234
42.278
0.183
70.205
0.157*
8.833
Acute toxicties following the EUP (described in Annex VI of Directive 67/548/EEC) asLC50 >100
or EC50 >100 (Not harmful), 10 < LC50<100 or 10< EC50<100 (Harmful), 1<L50< or1<
EC50<10(Toxic), and LC50 and LC50<1 or EC50< 1 (very toxic). While chronic toxicities following
the Chinese hazard evaluation criteria for new chemical substances (HJ/T154-2004), i.e., ChV >
10(Not Harmful), 1< ChV<10(Harmful), 0.1< ChV<1(Toxic), and ChV<0.1(Very Toxic)
4. Conclusion
CRediT authorship contribution statement
This study demonstrated the green synthesis of spherical
shaped, well dispersed, biologically and photo catalytically active
AgNPs using extract of medicinal plant Petroselinum crispum as
stabilizing source. The characteristics of the biosynthesized
AgNPs were studied by different techniques. The XRD analysis en-
sured the crystalline nature of the AgNPs. HRTEM analysis showed
that the particles are well dispersed with diameter in the range
25 nm to 90 nm. The results showed good antibacterial properties
of the synthesized AgNPs against Gram positive and Gram-
negative bacteria. The biosynthetic study of AgNPs demonstrated
high levels of scavenging DPPH free radicals. The biosynthesized
silver nanoparticles in this study exhibited remarkable photocata-
lytic degradation of BG dye. The results revealed that the green
synthesized AgNPs can have potential applications in pharmaceu-
tical science, food industry and textile as well as in environmental
remediation.
Noor Samad Shah: Research methodology and writing original draft.
Jibran Iqbal: writing review and editing.
Nawshad Muhammad: writing- review editing.
Muhammad Imran: Software validation.
Saad M. Alshehri: Project admiration, Resources, validation.
Arif Ullah Khan: Characterization and for analysis.
Murtaza Syed: Methodology writing and editing.
Naveed Ahmad: Drawing of figure and tables.
Amina Kousar: Original draft writing and formatting.
Munazza Ashfaq: Original draft and references setting.
Fares Howari: Conceptualization, writing -review and editing.
Kamran Tahir: Biological analysis.
Declaration of competing interest
The authors declare no competing financial interest.

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Acknowledgments
Dr. Zia Ul Haq Khan is grateful to the Higher Education Commission
of Pakistan for financial support under NRPU Project (No. 7814/Federal/
NRPU/R&D/HEC/2017). One of the authors (S.M. Alshehri) is grateful to
the Researchers Supporting Project number (RSP-2020/29), King Saud
University, Riyadh, Saudi Arabia for funding this research.
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