Journal of Photochemistry and Photobiology A: Chemistry 346 (2017) 470–478

Synthesis of Leucaena mediated silver nanoparticles: Assessing theirphotocatalytic degradation of Cr (VI) and in vitro cytotoxicity againstDLA cells

K. Kanagamania,b, P. Muthukrishnanb,*, M. Ilayarajac, J. Vinoth Kumard, K. Shankarb,A. Kathiresanb

aDepartment of Chemistry, SNS College of Technology, Coimbatore 641 035, IndiabDepartment of Chemistry, Faculty of Engineering, Karpagam Academy of Higher Education, Karpagam University, Coimbatore 641 021, IndiacDepartment of Chemistry, Arumugam Pillai Seethai Ammal College, Tirupattur 630 211, IndiadDepartment of Chemistry, VHNSN College, Virudhunagar 626 001, India

A R T I C L E I N F O

Article history:Received 15 March 2017Received in revised form 29 May 2017Accepted 16 June 2017Available online 23 June 2017

Keywords:Silver nanoparticlesPhoto degradation of Cr (VI)Cytotoxicity activity

A B S T R A C T

The development of dependable, environmentally benign methods for the synthesis of nanoscalematerial is an important concern of nanotechnology. In this work, it explores and finds the synthesis ofhighly dispersed silver nanoparticles (Ag-NP’s) with the help of Leucaena Leucocephala leaf extract (LLLE)as reducing agent. The synthesized Ag-NP’s was characterized by Fourier Transform Infraredspectroscopy (FT-IR), UV–vis Spectroscopy (UV–vis), X-ray diffraction (XRD) studies, TransmissionElectron Microscopy (TEM), Scanning Electron Microscopy (SEM) and Energy Dispersive X-rayspectroscopy (EDX). Moreover, the synthesized Ag-NP’s show the circular shape with average particlesize of 40 nm. Also the synthesized Ag-NP’s show better activity towards degradation of aqueoushexavalent chromium solution under visible light irradiation. Brunauer-Emmett-Teller (B.E.T) surfacearea analysis was done to explain the photodegtadation of chromium in aqueous solution. The short terminvitro cytotoxicity of the biosynthesized Ag-NP’s was tested against DLA cell lines using trypan blue dyeexclusion technique and thus the synthesized Ag-NP’s show 100% inhibition with concentration of100 mg/ml.

© 2017 Elsevier B.V. All rights reserved.

Contents lists available at ScienceDirect

Journal of Photochemistry and Photobiology A:Chemistry

journal home page : www.elsevier .com/ locat e/ jphotochem

1. Introduction

Metal nanoparticles find applications in various fields such asmedicine, material science, and pollution control and so on.Various strategies are employed for synthesis of metal nano-particles particularly silver nanoparticles including physical,chemical and biological methods. Subsequently chemical meth-ods based on simple procedures use chemical reducing agentswhich are toxic for living organisms and make them unfit formedicinal use. Among the various processes, biological processesbased on bacteria, fungi, plant extracts, bio-derived componentsare preferred as it does not employ toxic chemicals, ecofriendlyand has better morphological control of nanoparticles [1,2]. Sothere is an urgent need to develop ecofriendly biological way ofsynthesizing nanoparticles. Silver nanoparticles have long lasting

* Corresponding author.E-mail address: mukepmk@gmail.com (P. Muthukrishnan).

http://dx.doi.org/10.1016/j.jphotochem.2017.06.0211010-6030/© 2017 Elsevier B.V. All rights reserved.

inhibitory activity against various microbes and also againsthuman pathogens [3]. Kim et al. reported antifungal activity ofbiologically synthesized silver nanoparticles [4]. Anti-inflamma-tory activity of Ag-NPs was reported by Nadworny et al. [5].Similarly extensive research has been carried out on anti-viralactivity [5], anti-angiogenesis [6] and anti-platelet activity [7].Chemotherapy [8] is one of the important methods for thetreatment of cancer. However, there are certain drawbacks ofusing chemotherapy because of its inability to differentiatebetween normal and cancer affected cells. Dalton’s asciteslymphoma [9] is transplantable, cancer cells appearing aslymphocytes in mouse. Previous reports on in vitro cytotoxicitystudies provide data where it helps to identify plant extracts withpotential antitumor properties for the future work [10–14].Literature survey reports shows that biosynthesized Ag-NP’swas found to have excellent activity against several microbesand dental pathogens [15–19]. Cr (VI) is also one of the heavymetal contaminant in water released by Electroplating, leathertanning, and textile industries. Cr (VI) has high solubility in water,

00

K. Kanagamani et al. / Journal of Photochemistry and Photobiology A: Chemistry 346 (2017) 470–478 471

highly toxic and carcinogenic in human beings [20]. The removal ofCr (VI) from waste water involves techniques like chemicalprecipitation, ion exchange adsorption, membrane separation, andreduction [21–24]. The reduction of Cr (VI) to Cr (III) is consideredas an efficient method for the removal of Cr (VI) in water, BecauseCr (III) is mostly immobile and, which can be precipitated oradsorbed on a variety of substrates in neutral or alkalineconditions [25] the above methods need high capital cost whichreduces the usage of above methods for commercial purposes. Thereported techniques for chromium removal are catalytic conver-sion using metal nanoparticles as reducing agents. The presentwork was carried out to evaluate the cytotoxicity of silvernanoparticles biosynthesized from Leucaena Leucocephala leafextract against Dalton lymphoma ascites (DLA) cell lines: Dalton’slymphoma ascites (DLA) cell lines were used for short term in vitrocytotoxicity experiments. In addition, photocatalytic activity of theLeucaena mediated Ag-NPs was assessed by the degradation of Cr(VI) under visible light irradiation.

2. Materials and methods

2.1. Preparation of Leucaena Leucocephala leaf extract

The Leucaena Leucocephala leaf extract was made using freshleaves of Leucaena Leucocephala which was obtained in KarpagamUniversity campus, Coimbatore. The leaves were then cleaned withdeionized water and cut into small pieces. These leaf pieces (50 g)were added to 500 ml deionized water and allowed to boil for5 min. The resultant solution was then allowed to cool roomtemperature (approximately 28 �C). After that the solution wasfiltered through Whatman filter paper and the resultant filtratewas refrigerated for further use.

2.2. Biosynthesis of silver nanoparticles

The silver nitrate was purchased from Sigma-Aldrich (Banga-lore, India). The above leaf extract and 10�3M silver nitrate solutionwere added in the ratio (1:4) in a conical flask and the reaction wasleft to take place at ambient conditions. The change of colour fromcolourless to dark brown after addition of LLLE indicates theformation of silver nanoparticles. Reduction of elemental silverwas monitored using UV–vis techniques. Once the solutionreached dark brown colour, then the reaction of mixture wascentrifuged in order to collect silver nanoparticles. In addition thenanoparticle was washed additionally dual times with deminer-alized water for further characterization.

2.3. Stability of silver nanoparticles evaluated by UV–vis analysis

The formation of silver nanoparticles was monitored by UV–visspectra. Small aliquot of sample was drawn from the reactionmixture at regular time intervals and spectrum was recorded usingUV-1601 Shimadzu spectrophotometer.

2.4. Functional group analysis using FT-IR techniques

FT-IR spectra were recorded with frequency ranging from 400to 4000 cm�1 for the LLLE as well as the Leucaena mediated Ag-NPsin KBr matrix using SHIMADZU- FTIR- 8400S spectrophotometerinstrument (Tokyo Japan).

2.5. Morphological and elemental analysis

The synthesized nanoparticles were analyzed by quanta 200FEG scanning electron microscope (Resolution: 1.2 nm gold

particle separation on a carbon substrate Magnification: From amin of 12 � to greater than 1, 00,000 X) instrument attached withEDX Analyzer was employed using JEOL JED-2300analysis stationat accelerating voltage of 20 Kev.

2.6. HR-TEM Studies

The synthesized Ag-NP’s were characterized by HR-TEMtechniques with the help of JEOL JEM 2100 instrument. Thismicroscope helps to view lattice resolution of 0.14 nm and point-to-point resolution of 0.19 nm at 200 kV acceleration voltages. HR-TEM is equipped with Gatan Orious CCD camera (2K � 2K) forimage recording. The aqueous solution of silver nanoparticles waspoured as a drop on the carbon-coated copper grid and allowed todry at ambient temperature for 12 h and then analyzed. The size ofAg-NP’s in HR-TEM image was measured by using the image Jsoftware.

2.7. Characterization of metal and metal oxide phase by XRDtechniques

The formation of mono-phase compound was checked by XRDtechniques. Leucaena mediated Ag-NPs were washed thoroughly intriple distilled water centrifuged and dried at room temperature.The purified Ag-NPs was analyzed with XRD analysis by XRDGonimeter, (SHIMADO-Model XRD 6000). The scanning was donein the region of 2u between 20�–80 �C at 0.02�/Min and the timeconstant was 2s.

2.8. In vitro toxicity assay

The tumour cells were isolated from peritoneal cavity of tumourbearing mice and washed thrice with PBS or normal saline. Thecytotoxicity of the silver nanoparticles based on trypan blueexclusion method was determined by adding viable tumour cellsuspension of concentratiom (1 �106 cells in 0.1 ml) to tubescontaining different concentrations of silver nanoparticles rangingfrom 10 to 100 mg/ml and then the volume of the tubes was madeup to 1 ml using phosphate buffered saline (PBS) along with thecontrol tube containing only cell suspension. Finally, assay mixturewas incubated at 37 �C for 3 h. Then 0.1 ml of 1% trypan blue dyesolution was added to the tubes containing cell suspension andkept for 2–3 min and loaded on a haemocytometer. Dead cells takeup the blue colour of trypan blue while live cells do not take up thedye. The number of stained and unstained cells was separatelycounted.

% of cytotoxicity ¼ Number of dead cellsNumber of live cells þ Number of dead cells

� 1

2.9. Assessment of Ag-NPs as bio derived photo catalyst in reduction ofCr (VI)

The photo catalytic efficacy of the biosynthesized Ag-NPs wastested against Chromium solution under visible light irradiation.50 mg of the Ag-NPs was mixed with 75 ml of (10 mg/L) theChromium solution in 100 ml reaction vessel under visible lightirradiation (tungsten lamp (500 W) and the wavelength range of�420 nm). At different time intervals, 5 ml of aliquots was collectedby filtration and analyzed using UV–vis spectrophotometer. Beforeexposing to visible light, the suspensions were stirred magneticallyfor 1 h in dark condition to ensure the adsorption-desorptionequilibrium of the working solution. The rate of degradation ofChromium solution was estimated using the following equation.

Degradation rate ð%Þ ¼ ðCo � C= CoÞ � 100 ð1Þ

472 K. Kanagamani et al. / Journal of Photochemistry and Photobiology A: Chemistry 346 (2017) 470–478

Here, Co is the absorption intensity of initial chromium solutionand C is the main absorption peak intensity of chromium. After thephotocatalytic degradation test, the reaction mixture centrifugedfor 4 min at 2000 rpm. The catalyst was collected, soaked with DDwater for three times and then dried at 60�C for 8 h and used foreach cycle.

2.10. B.E.T surface area analysis

The BET was measured through volumetric absorption analyzerMicrometrics ASAP 2020 and the average pore diameters werederived from the N2 adsorption-Desorption isotherms by Barret-Joyner-Halenda (BJH) method.

3. Results and discussion

3.1. Evaluation of LLLE as biological reducing agent in Ag-NPs synthesis

Formation of silver nanoparticle and stability was confirmed byUV–vis spectroscopy. The reaction mixture changes the colour byadding metal ion of different concentrations. The progress of

Fig. 2. FT-IR spectra of a) LLLE b) Silver n

Fig. 1. (a) Effect of contact time for the reaction of 1 mM AgNO3 solution with 5% LLLE (b)the Ag-NPs solutions as a function of concentration of LLLE.

reaction was monitored by UV–vis spectra as shown in Fig. 1a[Time variation] and Fig. 1b [Concentration variation]. ControlAgNO3 solutions (without LLLE) neither developed the brown colornor did they show the characteristic peaks. These results specifiedthat non-living components reduction of AgNO3 did not occurunder the reaction conditions. Fig. 1a shows the UV–vis spectra ofAg-NPs formation at 1 mM AgNO3 with varies time interval such as5, 10, 15, 20, 25, 30, 35, 40, 60, 720 and 1440 min. The silver SurfacePlasmon Resonance (SPR) band occurs at 448 nm and graduallyincreases in intensity as function of time. The observed colourchange of the reaction mixture is due to surface resonancevibrations of the formed Ag-NPs. The dark brown colour of thereaction mixture is due to SPR arising because of the group of freeconduction electrons induced by an interacting electromagneticfield and the broadening of peak indicated that particles aremonodispersive in nature. Leaf Extract concentration ratio wasvaried from 1% to 5% LLLE with 1 mM AgNO3 as shown in Fig. 1b.The inset figure shows photographs of the test tubes (labeled a–e).It is observed that the SPR band occurs at 448 nm and intensity ofabsorption increases as a function of varying concentration of up to3% of LLLE leaf extract without any shift in the peak wavelength

anoparticles synthesized with LLLE.

Effect of LLLE concentration on the formation of silver nanoparticles. Inset photos of

Fig. 3. (a) HR-SEM image of Ag-NPs (b) EDX spectrum of silver nanoparticles. (c) TEM images of Ag-NPs at 20 nm (d) TEM images of Ag-NPs at 50 nm.

K. Kanagamani et al. / Journal of Photochemistry and Photobiology A: Chemistry 346 (2017) 470–478 473

indicating that the reaction is completed with 3% of LLLE leafextract and further increase in leaf extract concentration decreasesthe intensity of absorption. It is worthwhile mentioning thatAgNO3 can be completely reduced to form Ag-NPs which isconfirmed by the fact that there is no further change of UV–visspectrum after LLLE is introduced into as-prepared test solution.Prakash et al. [26] reported the reduction of argen ion andformation of stable Ag-NPs were found to take place within 2 h. Inthe present work, UV–vis spectra recorded in every 5 min intervalshows that absorption peak intensity steadily increased with time.However, the intensity of colour did not intensify after 24 h whichwas established by UV–vis spectra. The UV–vis spectra show thatthere is increase in absorption intensity with increase in timeclearly indicating the formation of silver nanoparticles. Stability ofthe reaction colloidal mixture was evaluated by UV–vis analyzerfor 40 days. Even after 40 days, the Ag-NPs peak at the sameabsorption intensity with the same wavelength. From theobservations, it was confirmed that the colloidal mixture wasstable even up to 40 days, which was convenient and verysupportive for the synthesis of Ag-NPs.

3.2. Role of functional groups in the green synthesis of spherical Ag-NPs

FT-IR measurements were done to identify the variousfunctional groups responsible for nanoparticle stabilization. FT-IR spectra of the LLLE and biosynthesized silver nanoparticles are

shown in Fig. 2a & b. FT-IR spectra LLLE depicted several absorptionbands at 3313, 2922, 2358, 1612, 1446, 1066, 898 and 596 cm�1

along with other small bands. These bands indicative of ��OH and/or ��NH, C��H bending modes in the hydrocarbon chains, C¼Ogroup, C¼C stretching, C��OH stretching vibrations, C��O stretch-ing and C��H bend of alkynes. FT-IR spectra of silver nanoparticles

Fig. 4. XRD spectrum of dried powder Ag-NPs.

Table 1Comparison of percentage cytotoxicity of Biosynthesized silver nanoparticles and standard drug curcumin against DLA cells.

S.No Silver nanoparticle Concentration(mg/ml)

Percentage cytotoxicity of DLA celllines

Standard drug Curcumin Concentration(mg/ml)

Percentage cytotoxicity of DLA celllines

1 10 55% 10 93.66%2 20 70% 20 96.19%3 50 84% 50 98.07%4 100 100% 100 100%5. 200 100% 200 100%

Fig. 5. In vitro toxicity assay of Ag-NPs using trypan blue dye exclusion method against DLA cells (100% live cells: White transparent cells and 100% dead cells: Dark opaquecells).

Fig. 6. Time dependent UV–vis spectral changes for the reduction of Cr (VI) to Cr

474 K. Kanagamani et al. / Journal of Photochemistry and Photobiology A: Chemistry 346 (2017) 470–478

reveal the broad peak at 3369 cm�1 which is due to stretchingvibrations of hydroxyl groups (��OH) groups. A weak absorption at2920 cm�1 could be assigned to aliphatic C��H stretchingvibrations. The peak at 2382 cm�1 corresponds to C��H asymmet-ric stretching. The strong absorption peak at 1618 cm�1 corre-sponds to C¼C stretching vibrations of aromatic ring. The peak1382 cm�1 may be due to ��OH bending vibrations of polyols suchas kaempferol-3-O-rubinoside and quercetin-3-O-rhamnosidepresent in leaf extract. The peak appearing at 1049 cm�1

corresponds to C��O stretching vibrations of phenolic groups.Moreover, the peak at 765 cm�1 is characteristic of aromatic ring. Inthis work, the donor of electrons was LLLE and the accepter was theAg+ ions in aqueous silver nitrate solutions. From the observations,it is confirmed that the reduction of Ag+ ions into Ag0, only on thebasics of the Vander Waals interactions between the supplier andthe acceptor.

3.3. HR-SEM and EDX Studies

The shape of the nanoparticles, purity and the completechemical composition of nanoparticles were investigated with thehelp of SEM and EDX techniques. Fig. 3a represents the SEM image

(III).

Fig. 7. Comparison of degradation ability of Cr6+ at different time intervals (a)Absence of light (b) Absence of catalyst (c) Chemically synthesized Ag and (d) As-synthesized Ag.

Fig. 8. Effect of amount of catalyst dosage on the photo reduction of Cr (VI).

K. Kanagamani et al. / Journal of Photochemistry and Photobiology A: Chemistry 346 (2017) 470–478 475

of LLLE mediated synthesis of Ag-NPs confirm the growth of silvernanoparticles. They were clearly distinguishable in 20–50 nm. Inthe present EDX analysis shown in Fig. 3b shows high percentage ofsilver indicating the purity of synthesized sample. Major identifi-cation lines confirm the formation of silver nanoparticles.

3.4. HR-TEM Analysis

Synthesis of stable nanoparticles with varying size plays a vitalrole in explaining their optical properties [27]. The size andmorphology of the synthesized Ag-NPs were characterized by TEMimages shown in Fig. 3c & d. The morphology of Ag-NP is almostspherical and average size of the particles in the range of 20–50 nmand mono dispersive in terms of particle size.

3.5. XRD studies

The size and the exact nature of Ag-NPs were determined byXRD analysis. The obtained diffraction peaks at 38.3, 46.5, 64.9,77.2 as shown in Fig. 4 corresponds to 111, 200, 211, 220 planes. Thisconfirms the FCC structure of Ag-NPs which was in goodagreement with standard to the unit cell of the structure (JCPDS:01-087-0717). The diffraction of peak of 32.3 may be related tocrystalline and amorphous organic phase.

3.6. Short term in vitro cytotoxicity assay

In the previous studies, [28] and [29] the anti-cancer activity ofvarious plant extract were reported. Short term in vitro cytotoxicityof the synthesized Ag-NPs was evaluated using trypan blue dyeexclusion method. Viable cells which remained unstained andstained cells by trypan blue was separately counted with the helpof haemocytometer. Cytotoxicity of Ag-NPs synthesized using LLLEis shown in Table 1. The percentage cytotoxicity of the DLA cells atvarious concentrations ranging from 10 mg/ml to 100 mg/mlexhibit a dose dependent inhibition on the development of DLAcells (Fig. 5a & b). Curcumin was used as a reference drug and thepercentage cytotoxicity of biosynthesized silver nanoparticles wascompared against the standard drug curcumin as shown in Table 1.The biosynthesized Ag-NPs show 100% activity at 100 mg/ml andthe standard drug shows only 81% at 100 mg/ml [30].

3.7. Evaluation of photocatalytic activity of Leucaena mediated Ag-NPs

The photocatalytic behavior of as-synthesized Ag-NP’s wereperformed towards the photoreduction toxic Cr6+ under visiblelight irradiation. The photodegradation process was scrutinized byusing major characteristic peak of Cr6+ at 350 nm over 50 mg of Ag-NP’s under visible light irradiation as depicted in Fig. 6. It obviousthat, the intensity of the major absorption peak at 350 nmdecreases with increasing time and the intensity reaches almostzero after 100 min, which implying that the complete photoreduc-tion of Cr6+ to Cr3+. Fig. 7 indicates that there was no significantreduction was observed in the absence of light and catalyst. Inaddition, LLLE assisted synthesis of Ag-NP’s exhibits excellentreduction performance than the chemically synthesized Ag-NPs.The enhanced photoreduction performance is due to the well-defined morphology and good crystalline nature of as-synthesizedAg-NP’s.

The effect of catalyst amount dosage on the photoreduction ofCr6+ was also performed to understand the optimum amount ofcatalyst loading, which could facilitate to avoid the ineffectiveoverload of the catalyst. Fig. 8 represents the amount Ag-NP’sphotocatalyst was varied from 25 to 100 mg at constant Cr6+

concentration and light sources. It observed that, the

photoreduction efficiency was increased with increasing catalystdosage from 25 to 50 mg beyond (above 50 mg) that the activity isdecreased. This might be due to the accumulations of catalyst thathindered the accessibility of the Cr6+ solution and light reaches tothe surface active sites of the catalyst. Hence, 50 mg of the Ag-NP’sdosage is much enough for the photo reduction of Cr6+. Thestability and reusability of the catalyst is an important parameterfor its practical applications. Therefore, the additional experimentswere performed for the photoreduction of Cr6+ over Ag-NP’s undervisible light irradiation and the results are demonstrated in Fig. 9. Itrevealed that, Ag-NP’s have excellent stability and recyclingperformances even after 5th cycle.

3.8. B.E.T analysis

The surface area is an important parameter for determining thephotocatalytic activity of nanoparticles. The surface area (SB.E.T(m2/g), pore volume (cm3/g) and pore size were calculated using B.E.T equation and the results are listed in Table 2. The N2

adsorption–desorption isotherms of Ag-NPs was measured at�195.876 �C and the isotherms is depicted in Fig. 10. The specific

Table 2BET surface area, pore volume and pore size of the photo catalysts.

Tested sample BET Surface area (m2/g) Pore volume (cm3/g) Pore size (nm)

Silver Nanoparticles 7.6753 0.014745 7.68429

476 K. Kanagamani et al. / Journal of Photochemistry and Photobiology A: Chemistry 346 (2017) 470–478

surface area, pore volume and pore size of the Ag-NPs are7.6753 m2/g, 0.014745 cm3/g, 7.68429 nm, respectively. The iso-therm obtained is identified as hysteresis loops of type III. It is acharacteristic of mesoporous (2–50 nm) materials according to theIUPAC classification [31]. The surface area, pore volume and poresize of the Ag-NPs are higher which in turn increases the photoreduction of chromium. The increase in surface area is due to theexistence crystalline phase, which increases the adsorption

Fig. 9. Reusability study of Ag-NPs for the photo degradation of Cr6+.

Fig. 10. Nitrogen adsorption-des

capacity of the nanoparticles. The high mesoporous nature, surfacearea, adsorption capacity could significantly improve its photo-catalytic activity [32,33]. However, the excellent photocatalyticactivity of biosynthesized silver nanoparticles can be attributed tothe direct electron ejection from the HOMO of Ag to the hexavalentchromium thereby reducing to Cr3+.

3.9. Mechanism of photo reduction of chromium (VI)

The plausible mechanism for the photocatalytic reduction wasgiven in equations 1–5. Fig. 11 shows the schematic representationof chromium reduction under visible light irradiation using Ag-NPs. The Ag nanoparticles were excited upon illumination withvisible light, as a result the electron may excited which goes to theconduction band (CB) while leaving a hole in the valance band (VB)as given in Eq. (1). Moreover, the electron in the conduction bandreacts with atmospheric oxygen and forms the superoxide radicalanion as given in Eq. (2). Furthermore, the superoxide radical anionreacts with Cr2O7

2� and reduces Cr6+ to Cr3+ and forms H2O(Eq. (3))

Ag þ hv ! Agðhþ þ e�Þ ð1Þ

Ag eð Þ þ O2!��O2 ð2Þ

Cr2O72� þ 14Hþ þ 6�O2 ! 2Cr3þ þ 7 H2O þ O2 ð3Þ

2H2O þ 4hþ ! O2 þ 4Hþ ð4Þ

orption isotherm of Ag-NPs.

Fig. 11. Schematic diagram representing the mechanism of chromium reductionunder visible light irradiation using Ag-NPs.

K. Kanagamani et al. / Journal of Photochemistry and Photobiology A: Chemistry 346 (2017) 470–478 477

H2O þ hþ ! HO� þ Hþ ð5Þ

Cr6þ þ H2O2 þ Hþ ! Cr3þ þ H2O þ O2 ð6ÞThe above process repeats for the complete photocatalytic

reduction of Cr and The H2O2 itself produced in the photocatalyticreaction may also be actively participated in the photocatalyticreduction of Cr6+ to Cr3+ as given in Eqs. (4)–(6).

4. Conclusion

For the first time, the biosynthesis of Ag-NPs using LeucaenaLeucocephala leaf extract was developed. The biosynthesized Ag-NPs show spherical shape with particle size in the range of 20–50 nm. The present study explores the antitumor activity ofbiosynthesized Ag-NPs in DLA tumor cells and it can be used as analternate therapeutic agent for the treatment of cancer. The photodegradation of chromium under visible irradiation in aqueoussolution reveals that synthesized Ag-NPs have better reducingability to reduce Cr6+ to Cr3+. Hence the biosynthesized silvernanoparticle is reported to possess antitumor activity and betterreducing ability to reduce heavy metal ions.

Acknowledgements

This research did not receive any specific grant from fundingagencies in the public, commercial and other sectors.

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