Introduction

Bio-fabrication of silver nanoparticles by harnessing the natural abilities of the plant secondary metabolites provide a one-step process that not only converts the bulk material into their nano-forms by redox chemical reactions but also contributes to shield metallic nanocore by covering the surface with functional groups found primarily in plant body (Sharma et al. 2009; Manosalva et al. 2019). Nanoparticles of silver, because of their unique size, shape and structure have abilities to interact with the plasma cell membrane and control the proliferation of the organisms (Siddiqui et al. 2018; Khatami et al. 2018; Behravan et al. 2019).

Leishmaniasis is a disease of an intracellular parasite spread by the bites of a phlebotomine sand-fly. This disease is usually caused by a protozoan belongs to a Genus Leishmania and causes acute to chronic ailments that range from cutaneous ulcers to mutilating mucocutaneous disease and sometimes it causes severe systematic illnesses to the infected persons (Nadhman et al. 2014). The conventional treatment of Leishmania involves the use of different inhibitory drugs but the microorganism attains resistance after some time and results in the more severe action or attack of disease which makes it difficult to control (Iqbal et al. 2019b). The use of nanoparticles plays a very important role to kill microorganisms without allowing them to develop resistance (Abbasi et al. 2019).

Multiple drug resistance is another issue that deals with the abilities of microorganisms to attain resistance against modern drugs due to drug abuse and poor management (Pareek et al. 2018; Alavi et al. 2019). Drug resistance is reckoned as a leading cause of mortality and morbidity in the coming decade and will be effecting organisms more severely than ever before (Rai et al. 2017). Xanthomonas oryzae is a Gram-negative bacterial strain and is responsible to cause a bacterial blight on rice plants. This is a major problem in tropical Asia where high yield rice crops are mainly infected by this bacterium. It causes vascular disease and grows in the form of lesions of white or grey color along with the veins of a leaf (Bai et al. 2000). Xanthomonas vesicatoria is a rod-shaped Gram-negative bacterium that is responsible to cause bacterial spots on the leaves of tomato and pepper plants. After getting infected with this bacterium the symptoms become visible on the above-ground plant parts such as on stem canker, fruit and the leaves spots become easily visible (Ciardi et al. 2000). Ralstonia solanacearum is a Gram-negative anaerobic pathogenic bacterium that has a wide range of plant hosts and mostly colonizes in the xylem of the plant body to cause bacterial wilt. It affects potato, tomato, olive, banana, ginger, soya bean, rose, and tobacco plants (Champoiseau et al. 2009). Erwinia carotovora is also a Gram-negative rod-shaped bacterium that was first identified from the carrot plant. It is responsible to cause infections to a variety of plants including carrots, lettuces, potatoes, cucumbers, onions, tomatoes, and many ornamental plants. It infects the plant tissues both in situ and in storage. It results in the softening of the plant tissues and makes them watery and slimy and causes fouling smell (Dong et al. 2004).

The surface covering of nanoparticles has functional groups that originate from secondary metabolites and provide various attributes and underpin their suitability for photodynamic applications. Photodynamic mobilization of a drug depends on its photooxidative and photothermal potentialities (He et al. 2020). Photodynamic therapy plays a very important role to manipulate the electromagnetic and kinetic potential of nanoparticles by exciting them on a suitable wavelength usually at visible and infrared light which helps to release reactive oxygen species (ROS) usually singlet oxygen (1O2) and other ROS (Beik et al. 2019). The release of free electrons results in the disruption of cells homeostasis and osmotic potential by kinetic movement and ionic balance by unregulated ion flow and eventually leads to cell death (Lamch et al. 2018). The development of new photo-nanodynamic drugs provides the most modern platform to the researchers to combat the war of proliferating vicious pathogens.

Herein we report (detailed layout of the study is represented in Scheme 1) the use of Ag nanoparticles of different shapes, sizes, and morphologies, phytosynthesized from Mentha arvensis to eradicate Leishmania and plant bacterial pathogens and determination of their photodynamic potential.

Scheme 1
scheme 1

Schematic layout of the work

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Materials and methods

Processing of plant material

Mentha arvensis has purchased from the local farmers market Sialkot (32.485272° N 74.543575° E) Pakistan. Samples were washed, dried to remove the moisture, chopped into small pieces and pulverized in the kitchen grinding machine to make a fine powder. For the preparation of aqueous extracts 1 to 10 ratio of plant material and distilled water was prepared respectively and heated on a hot plate at 45–65 °C for 10–20 min. After the boiling, the aqueous extract was filtered and used immediately as fresh for the reduction of silver salt (Alshehri et al. 2019).

Chemical reagents

The chemical reagents purchased for the synthesis of silver nanoparticles were of analytic grade and used as received without any further purification.

Synthesis of silver nanoparticles

Silver nitrate solution of 5 mM concentration was mixed with freshly prepared plant extract in a ratio of 1:9 of plant extract and AgNO3 solution respectively. The reaction was carried out at 5.88 pH, the temperature was maintained at 60 °C and the reaction mixture was stirred continuously. An aliquot was taken out from the flask and the absorbance was measured by using crystalline Quartz cuvettes with the help of UV–visible spectrophotometer (Shimadzu 1601, Japan) in the range of 200–900 nm of the wavelength of light. Absorbance was measured after a specified interval of time to observe the reaction kinetics at different incubation periods to determine the synthesis and the yield of AgNPs. After the completion, the reaction was quenched by removing the flask from the hot plate and diluted with a small amount of distilled water. The reaction mixture was centrifuged at 1000×g (Sorvall RT 7 Plus) for 1 h, washed with methanol and distilled water thrice to separate the AgNPs from the reaction mixture (Akhtar et al. 2013; Ali et al. 2016; Kim et al. 2016).

Morphological characterization

Characterization of synthesized silver nanoparticles was performed by using different material characterization techniques to explore their morphologies. Characterization was done initially by visual observation that involves the comparison of reaction mixture before and after synthesis. UV–visible Spectrophotometer (Shimadzu 1601, Japan) was used to measure the absorbance of the reaction mixture at various intervals of incubation to confirm the highest yield and synthesis (Huang et al. 2019). Scanning Electron Microscope (SEM) JEOL 7500F HRSEM, was used to get a mean size and shape of nanoparticles by observing the sample placed on copper grids under different lens and voltages of a microscope (Thirumagal and Jeyakumari 2019). Energy-dispersive X-ray analysis (EDX) was performed to check the elemental composition of the sample by using detectors associated with JEOL 7500F HRSEM (Alsammarraie et al. 2018). Atomic Force Microscopy (AFM) images were collected on Agilent 5500 AFM and the sample was placed on a silicon wafer and was prepared on a spin coater machine (Laurell WS-650Mz-23NPP) to spread AgNPs (Li et al. 2019). The hydrodynamic diameter of NPs was measured by using the dynamic light scattering (DLS) machine of Malvern Instruments particle sizer, Zetasizer Nano S, Malvern Instruments, UK. The sample was prepared into 1× PBS solution and 1 ml of solution was observed at 25 °C by using laser and other reaction parameters were adjusted automatically by automatic machine settings (Satsangi 2019).

Biocompatibility assessment (Hemolysis Assay)

The biocompatibility of AgNPs was studied by using the hemolytic assay. Human fresh red blood cells (RBCs) (collected after oral consent and approval by University Bioethical Committee) were washed several times by using Hank’s Buffer Salt Solution (HBSS). After the washing of the RBCs, the 180 μl of RBCs suspension (in HBSS 4% Volume) was placed in 96-well plate and AgNPs were prepared in different doses and introduced to RBCs. After that plates were incubated for 3 h in 5% CO2 chamber and the temperature was maintained at 37 °C. The cell suspension was taken in Eppendorf tubes and centrifuged at 1000×g for 5 min. The release of the hemoglobin pigment by the ruptured RBCs was measured at 576 nm of the wavelength of the light by taking the supernatant from 96-well plate and measured by using a microplate reader (Thermo Fisher). Negative control was maintained by using RBCs in HBSS without AgNPs while the positive control was maintained by using Triton X-100 (0.1%). Percentage hemolysis was determined by using the following formula. Lethality dose (LD50, LD90, and LD100) was recorded by using GraphPad Prism® software and plotted into a graph (Nadhman et al. 2015; Iqbal et al. 2019a);

$$ {\text{Hemolysis }}\left({ \%} \right) = \frac{{{\text{OD at }}\;576{\text{ nm in the nanoparticle solution}} - {\text{OD at }}\;576{\text{ nm in HBBS }}}}{{{\text{OD at}}\;{ }576{\text{ nm in }}\;0.1{\%}{\text{ Triton X}} - 100 - {\text{OD at }}\;576{\text{ nm in HBBS }}}} \times 100 $$

L. tropica culture maintenance

Leishmania tropica (KWH23) were maintained on medium 199 (M199) (Gibco, Invitrogen, USA). The medium was supplemented with 10% heat-inactivated fetal bovine serum (PAA, Austria), 100 mg/ml of streptomycin and 100 μg/ml of penicillin (Sigma, USA) (Nadhman et al. 2014, 2015).

Anti-Leishmania activity measurement

A stock solution of AgNPs (1 mg/ml) was prepared in deionized water. L. tropica were grown in M199 medium for 7 days at 24 °C. L. tropica cells were suspended into 96-well microtiter plate and the serial dilution of AgNPs were prepared (500 μg/ml, 250 μg/ml, 100 μg/ml, 10 μg/ml, 5 μg/ml, 1 μg/ml, 0.1 μg/ml and 0.01 μg/ml). Cells viability was measured by doing counting on the Neubauer chamber (Thermo Fisher) by observing their motility with trypan blue die. IC50 was measured by using GraphPad Prism® Software (Nadhman et al. 2014, 2015; Iqbal et al. 2019a).

Antimicrobial activity evaluation against plant bacterial pathogens

All bacterial plant pathogens (Erwinia carotovora, Xanthomonas vesicatoria, Xanthomonas oryzae and Ralstonia solanacearum) (Plant Pathology Department, Agriculture University, Peshawar) (Naz et al. 2020) were grown overnight in Luria Bertani liquid media (tryptone = 10 g, yeast extract = 5 g and NaCl = 10 g in 1 L of distilled water; pH 7.2) and 1 × 108 cells/ml were maintained. Cells were plated into 96-well microtiter plates. Different concentrations of the AgNPs 500 µg/ml, 250 µg/ml, 100 µg/ml, 10 µg/ml, 1 µg/ml, 0.1 µg/ml, and 0.01 µg/ml were prepared and introduced to their receptive wells on the plate. Plates were incubated for 24 h at 37 °C on a rotatory shaker. After 24 h plates were read by measuring the absorbance at 600 nm of a microplate reader (Thermo Fisher, USA). The data were expressed in the form of % survival of bacterial pathogens against different nanoparticle concentrations (Nadhman et al. 2015).

ROS quantification

ROS generation by AgNPs was measured by preparing the DPBF solution (0.1 mM DPBF in ethanol). 10 μg/ml of AgNPs were dissolved into 2 ml of DPBF solution. The reaction was carried out into sealed Quartz cuvettes with IR filter (400–800 nm) for 30 s under sunlight. After each 30 s photobleaching of the DPBF was measured by using UV-3000 Spectrophotometer for 5 min. Methylene blue was used as a control (Nadhman et al. 2014, 2015).

Photothermal activity measurement

AgNPs were suspended into distilled water at a concentration of 1 mg/ml. The test tube containing the test sample was exposed to sunlight and after each minute temperature of the sample was recorded by dipping the temperature prob (Thermo scientific, USA). This procedure was continued for 30 min and a plot was drawn in-between time and temperature changed (Iqbal et al. 2019a).

Data analysis

All the experiments in this study were performed in triplicate and were expressed in the form of mean and standard deviation. MS Excel® was used to plot graphs and figures. Fiji image J® was used for the arrangement of microscopic images. T test was performed to analyze statistical differences in the results of antimicrobial, anti-leishmanial activity, photothermal activity and hemolysis assays and P < 0.05 was used to indicate significant difference.

Results

Phyto synthesis of AgNPs

Ag nanoparticles were synthesized by modulation of physicochemical parameters such as temperature, pH, the concentration of AgNO3, concentration of plant extract and the ratio of reactants in our lab previously. It was confirmed that the physicochemical toolbox plays a very important role to steer the process of AgNPs synthesis and affects greatly the size, shape and biological corona of AgNPs that can change their biomedical nature (Beddoes et al. 2015). It was observed that the 5 mM of AgNO3 at 60 °C and pH of the reactants after mixing were maintained at 5.88 appeared as optimum conditions for the synthesis of AgNPs by mixing plant aqueous extract and silver salt in 1 to 9 ratios respectively (Fig. 1 inset). UV–visible spectrums showed the characteristic surface plasmon resonance (SPR) band at 485 nm in between 350 and 650 nm of the light wavelength (Fig. 1).

Fig. 1
figure 1

UV–visible spectrum representing the time-dependent synthesis of AgNPs. Inset is showing a change in the color of the reaction mixture after the synthesis of AgNPs

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Physical characterization of AgNPs

The morphological characterization of AgNPs synthesized by the plant-mediated eco-friendly method was performed mainly by using SEM and AFM. SEM micrographs showed that NPs are spherical and have a size range of ~ 20–100 nm (Fig. 2a, b) which was further confirmed by using AFM images. AFM reported NPs of very small sizes and most of the NPs were found to be in a range of ~ 10–100 nm. AFM images again explained that the NPs are spherical (Fig. 3). The elemental composition of AgNPs was obtained by using EDX analysis (Fig. 2c). The characteristic peak of the Ag has observed at 3 keV and the intensity of the Ag signal was ~ 81%. No elemental O2 was reported which showed that these nanoparticles are non-oxidative. It also reported the presence of C, Cl, Si, Mg, and Cu as 2.87%, 11.75%, 0.87%, 0.38%, and 3.62% respectively in trace amount. DLS analysis determined the particle size distribution and it was found between ~ 14 and 32 nm which represents the size range of most of the colloidal nanoparticles (Fig. 4) while the average size of a single nanoparticle was recorded at 20.46 nm. Polydispersity index was recorded as 0.220 which explains that these nanoparticles are monodisperse and are very suitable for biomedical applications.

Fig. 2
figure 2

a, b SEM micrographs representing that the AgNPs are spherical and have a size range of ~ 20–100 nm c EDX analysis of the AgNPs representing a peak of Ag at a characteristic region of 3.0 keV

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Fig. 3
figure 3

AFM micrographs of AgNPs. Nanoparticles in Red circles are showing that they are spherical and have a size range of ~ 10–100 nm

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Fig. 4
figure 4

Size distribution of AgNPs measured by using DLS analysis. Size distribution by number was observed between ~ 14 and 32 nm while the average size of a single nanoparticle was recorded as 20.46 nm. Polydispersity was recorded as 0.220

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Biocompatibility measurement of AgNPs (hemolysis)

Hemolysis assay provides a preliminary base to determine the biocompatibility of NPs. Hemolysis assay results were measured in terms of Lethal Dose (LD). LD50, LD90, and LD100 (Fig. 5) showed that a very high dose of the AgNPs is required to cause toxicity against human RBCs. 214 μg/ml was reported to be a lethal dose to kill 100% population of the test samples while a very minimal dose of the AgNPs (10 μg/ml) was found effective against L. tropica. LD50 and LD90 were recorded as 76 μg/ml and 184 μg/ml respectively which manifested a dose-responsive activity of AgNPs (P < 0.05).

Fig. 5
figure 5

Biocompatibility Measurement. LD50, LD90 and LD100 of AgNPs. Increasing lethal dose resulted in increased cytotoxicity of AgNPs against RBCs

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Measurement of the dose-dependent response of the AgNPs against Leishmania tropica

Leishmaniasis is a disease which is caused by the bites of Phlebotomine sand-fly. Around 700,000 to 1 million new cases and some 26,000–65,000 deaths are reported annually by Leishmaniasis (WHO) (Iqbal et al. 2019b). AgNPs expressed a significant dose-dependent response against Leishmania (P < 0.05) and it was found that increasing the dose of AgNPs has more strong effects on the growth or the viability of Leishmania (Fig. 6). IC50 measurement showed that the 13.1 μg/ml of AgNPs dose is required to affect the growth of protozoans. It was observed that the 500 μg/ml of AgNPs killed 100% cells and the viability increased by decreasing the concentration of AgNPs (P < 0.05). Almost 50% of the population of the Leishmania found dead by using 10 μg/ml of AgNPs which is showing that these NPs are highly biocompatible as a very high dosage is required to affect the growth or to cause cytotoxicity to RBCs.

Fig. 6
figure 6

Anti-leishmanial activity of different doses of silver nanoparticles represents the dose-responsive activity. Increasing the dose of silver nanoparticles resulted in decreasing viability percentage

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Measurement of the dose-dependent response of the AgNPs against plant bacterial pathogens

The dose-dependent activities of AgNPs were measured against E. carotovora, X. vesicatoria, X. oryzae and R. solanacearum. AgNPs were found to be highly effective against all pathogens and manifested dose-dependent responses (Fig. 7). As the concentration of the AgNPs dose decreased from 500 µg/ml, 250 µg/ml, 100 µg/ml, 10 µg/ml, 1 µg/ml, 0.1 µg/ml to 0.01 µg/ml, survival % of the bacterial pathogens increased significantly (P < 0.05). AgNPs manifested the MIC around 12 µg/ml against all pathogens which shows the potential of these nano-moieties to may act as a pesticide against plant disease-causing pathogens. The dose-dependent responses of bacterial pathogens were recorded in between 2 and 12 µg/ml. Ampicillin was used as a positive control and water was used as a negative control. The highest inhibition of pathogens at 10 µg/ml of ampicillin dose was 90%, 68.2%, 72% and 71.79% against X. vesicatoria, E. carotovora, R. solanacearum, and X. oryzae respectively. This inhibitory effect of AgNPs is because of the unique physical and chemical characteristics that provide them with abilities to enter bacterial cytoplasm by crossing plasma cell membrane barriers and to kill them eventually by disruption of ionic balance and rupturing membrane (Du et al. 2018).

Fig. 7
figure 7

Dose-dependent response of AgNPs against plant bacterial pathogens. 12 µg/ml was recorded as the MIC

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ROS quantification of AgNPs

The generation of free radicals plays a very important role to increase the cytotoxic abilities of nano-antibiotic drugs. ROS scavenge the ionic potential of the cells and disturb the osmotic balance which results in the disruption of the plasma cell membrane and the death of the cell. Our AgNPs expressed zero quantum yield.

Photo-thermal activity determination of AgNPs

Photo-thermal activity measurement did not report any change in temperature of AgNPs and the temperature remained constant even after 30 min (Fig. 8). Change in temperature of the NPs containing sample is reported if NPs have O2 in them. Change in temperature also plays a very important role to use NPs as a photodynamic agent to treat dreading diseases including cancer and Leishmania. So, the results of our study showed that AgNPs synthesized from M. arvensis cannot be used as a photodynamic agent in the photothermal treatment of ailments.

Fig. 8
figure 8

Photothermal activity of AgNPs. Straight line showing no change in temperature of AgNPs even after 30 min exposure to sunlight

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Discussion

Specialized mechanisms that are responsible for developing antimicrobial resistance include drug/antibiotic selective pressure, housekeeping genes that code for the proteins or transporters to expel the antimicrobial drug out of the bacterial cell and results in decreasing the dose and have effects on the bacterial population, enzymatic inhibition of drugs and chemical modification of targeted sites leads to the development of multiple drug-resistant (MDR) organisms (Rai et al. 2017). So the present study involves the use of sustainable non-oxidative silver nanoparticles to treat microbial proliferations. Biogenic synthesis of AgNPs provides advantages to manufacture biocompatible nanodrugs for human applications. Plant bodies have various secondary metabolites that vary among species to species and sometimes the same plant species have different concentrations and constituents of phytometabolites due to spatial and temporal variations (Gobbo-Neto et al. 2017). The use of a 1 to 9 ratio of plant extract and silver salt reported the consumption of a very meager amount of secondary metabolites to reduce and stabilize AgNPs which guarantee reproducibility. Change in the color of the reaction mixture which is attributed to the response of AgNPs to light was observed initially to report synthesis (Fig. 1 inset). Surface plasmon resonance (SPR) band which is a result of the vibration of free electrons of AgNPs in coordination with the metal lattice in resonance and the oscillating electromagnetic field of light waves, was observed at 485 nm (Nindawat and Agrawal 2019). An increase in the incubation period of reactants resulted in increasing the absorbance at a higher wavelength which is called Redshift (460–485 nm, Fig. 1). According to Mie’s theory, small molecules absorb light at a smaller wavelength while large molecules absorb light at a longer wavelength (Ulaeto et al. 2019). The microscopic structural evaluation showed that AgNPs are spherical and monodisperse and exist between ~ 20 and 100 nm. Particle size analysis manifested that most of the NPs are in the range of ~ 14–32 nm which is showing that the nanoparticles are very small in size and the narrow dispersity was recorded (PDI 0.220) which shows that the NPs are suitable for biomedical applications.

Biocompatibility is the main feature that contributes toward the application of NPs on different life forms, which was confirmed by using hemolysis assay (Jadhav et al. 2018). Blood is the main connective tissue in the human’s and the animal’s body. It supplies and exchange nutrients, maintain pH, transport hormones, deliver oxygen, transfer biochemical signals, immune response, defense mechanisms, maintain homeostasis and also act as a site for many biochemical reactions (Iqbal et al. 2019b; Parthiban et al. 2019). Figure 5 manifested the biocompatibility results of AgNPs. Biological applications of the NPs implicated in this study found that the NPs are highly biocompatible and a single dose of 10 μg/ml of NPs is enough to eradicate almost 50% of the Leishmania population. AgNPs were observed biocompatible at a lower dose and increasing dose induced the rupturing of RBCs. The selective activity of AgNPs against Leishmania cells can be because of the presence of chlorides in colloidal AgNPs. Chlorides contribute to exchange bicarbonates (HCO3−) across the plasma cell membrane of the RBCs or erythrocytes and help to maintain ionic balance which is termed as chloride shift. The chloride ions form strong acids upon reaction to the water which may result in the antimicrobial activities against Leishmania and plant bacterial pathogens (Westen and Prange 2003). The biocompatibility of the AgNPs depends on the method of the synthesis and the surface modifications of the NPs. Surface functional groups play an important role to shield the metallic core of AgNPs and belong to plant secondary metabolites originally that prevent the agglomeration of NPs and make them compatible for humans and other animals (Akhtar et al. 2013).

The dose-responsive activity was observed against Leishmania tropica and plant bacterial pathogens such as Erwinia carotovora, Xanthomonas vesicatoria, Xanthomonas oryzae, and Ralstonia solanacearum. It was observed that increasing the dose of the drug resulted in increasing the drug pressure on microorganisms, which promoted the process of killing (Sharma et al. 2009). At a higher dose 500 μg/ml and 250 μg/ml, there was no active growth of Leishmania parasite responsible to cause Leishmaniasis but the viability of the organisms increased with decreasing the dose while 10 μg/ml was found effective to kill more than 50% of the test population which is a great number. Plant bacterial pathogens were found highly susceptible against AgNPs and antimicrobial activity was recorded between 2 and 12 μg/ml and MIC was observed as 12 μg/ml. Our results are in favor of some previously published scientific reports (Jemilugba et al. 2019; Behravan et al. 2019; Anandan et al. 2019). Elemental composition analysis confirmed the presence of Cl (11.75%) in AgNPs. Chlorine-containing sesquiterpenes and monoterpene can be responsible for the presence of Cl (Dembitsky 2002; Shaiq Ali et al. 2002). Some previous reports established the antimicrobial potential of Cl (Odlaug 1981; Gottardi and Nagl 2005; Kim et al. 2008) and the presence of high chlorine contents in M. arvensis fabricated AgNPs can be one reason for their selective antimicrobial activities. Other factors responsible for the antimicrobial potential of AgNPs against Leishmania and plant bacterial pathogens can be a small size that helps nanoparticles to pass the plasma cell membrane barrier and enter the cytoplasm and fragment the DNA structure. Nanoparticles also have abilities to disrupt the ionic potential of cell membrane (Jadhav et al. 2018), bind with the thiol group (–SH) of respiratory enzyme’s active sites (Behravan et al. 2019) and also interact with subcellular organelles such as mitochondria that eventually leads to cell death (Huang et al. 2011).

The generation of free radicals performs a significant job to build the cytotoxic capacity of pharmaceutical medications. A past report (Nadhman et al. 2015) proposed a direct relationship of the ROS generation with the cytotoxic potential of the oxidative-nanoparticles but our outcomes communicated zero quantum yield. Our results are indicating that ROS is not the only factor behind the cytotoxic capacities of the nanoparticles and there is no immediate or direct relationship in the generation of ROS and cytotoxic abilities in terms of non-oxidative nanoparticles. EDX investigation of the AgNPs additionally affirmed that there is no elemental O2. Change in temperature of the NPs containing test sample is accounted for if NPs have O2 in them. Temperature additionally plays a particularly significant role to utilize NPs as a photothermal agent to treat disease such as Leishmaniasis (Jiang et al. 2020) so the outcomes of our investigation indicated that AgNPs synthesized from M. arvensis cannot be utilized as a photodynamic agents in the photothermal treatment of diseases but they have a very strong potential to eradicate the population of Leishmania and plant bacterial pathogens due to their small size and biochemical nature.

Conclusion

Our findings explain the use of plant aqueous extract from Mentha arvensis for the synthesis of silver nanoparticles by the reduction of bulk silver. Biocompatible nature of silver nanoparticles favors their human applications though they are highly effective and efficacious against Leishmania tropica and plant bacterial pathogens. Photooxidative and photothermal analysis revealed that the non-oxidative silver nanoparticles do not have the potential to be used as photodynamic agents. This study provides experimental evidence to use NPs from M. arvensis to develop efficacious antimicrobial drugs to selectively target Leishmania and plant bacterial pathogens. Future perspectives of this work include understanding the effects of different physicochemical reaction parameters on nanoparticle corona and carving nanoparticles with different surface ligands for their targeted delivery to infected sites for photodynamic therapies.