Green synthesis of iron oxide nanoparticle using Carica papaya leaf extract and it's importance

Green synthesis of iron oxide nanoparticle using Carica papaya leaf extract and it's study of medicinal application and antimicrobial activity.

Synthesis of iron oxide nanoparticles by the recently developed green approach is extremely promising because of its non-toxicity and environmentally friendly behavior. In this study, nano scaled iron oxide particles (α-Fe2O3) were synthesized from hexahydrate ferric chloride (FeCl3.6H2O) with the addition of papaya (Carica papaya) leaf extract under atmospheric conditions. The synthesis of iron oxide nanoparticles was confirmed by systematic characterization using FTIR, XRD, FESEM, EDX and TGA studies. The removal efficiency of remazol yellow RR dye with the synthesized iron oxide nanoparticles as a photocatalyst was determined along with emphasizing on the parameters of catalyst dosage, initial dye concentration and pH.

 Methods to synthesis of iron oxide nanoparticle 

The papaya plant (Carica papaya) leaves were collected. The fresh leaves were then washed multiple times with tap water followed by deionized water. The leaves were then dried in oven for an hour and then grinded to from fine powder.

20 grams of fine powders are boiled with 1L of deionized water at 80
C for 30 min and the extract is then filtered using Whatman no 42 filter paper. The filtrate was concentrated using rotary evaporator and stored at 40
C for further use.  

Green synthesis of α-Fe2O3 nanoparticles

Ferric chloride hexahydrate (FeCl3.6H2O) was used as the precursor for the synthesis of the α-Fe2O3 nanoparticles. 50 mL of the papaya leaves extract was added dropwise with 50 mL of 0.1M FeCl3.6H2O solution in 1:1 ratio at room temperature. Following this, 1 M NaOH was added till the pH became 11. The resultant mixture was stirred using a magnetic stirrer for 30 min and the formation of intense black colored solution confirmed the synthesis of iron oxide nanoparticles.

The nanoparticles were separated by centrifugation at 8000 rpm for 20 min and cleansed by subsequent washing with ethanol and water for 2–3 times. The NPs were finally dried in a hot air oven at 80°C for 3 hr and stored in a seal tight container for further use. 

Characterization of iron oxide nanoparticle 

FT-IR spectra of sample was recorded on a FT-IR 8400S spectrophotometer in the wavenumber range of 4000–400 cm-1. XRD patterns were recorded by an x-ray diffractometer by using Cu kα radiation (λ ¼

0.154) from a broad focus Cu tube operated at 40 KV and 40 MA. The morphology of nanoparticles was analyzed by means of field emission scanning electron microscope run at a voltage of 5.0 KV. The UV-VIS spectra of the sample to measure the absorbance of the dye which were done by using the double beam UV-1700 Series Spectrophotometer. 

Antibacterial activity of iron oxide nanoparticle 

Well diffusion method by agar plates was used for calculating the zone of inhibition. Clinical pathogenic bacteria Klebsiella spp. strain KH15, E.Coli strain EH9, Pseudomonas spp. strain PsI1strain PsI1, S.aureus strain 6s were developed on nutrient agar plate and maintained at 37°C for whole night. The overnight culture of bacteria in nutrient broth was used for the experiment. In this method, sterilized nutrient agar plate was equipped for each bacterium. All bacterial culture was adjusted in optical density (OD) 0.1 using UV Visible Spectrophotometer. The spectrophotometer was first made auto zero using blank to eliminate the effect of assay reagents. These three bacterial pathogens were then coated over the agar plate with the help of sterile swab of cotton. Then these plates were permitted to dry. After that, one wells were bored by a sterile well cutter (7.0 mm diameter) in each agar plate. Subsequently, the suspension of NPs (5mg/ml, 20 mg/ml and 30 mg/ml) was poured into individual wells for each strain. The plates were permitted to put for 1 h for complete diffusion followed by incubation at 37
C for 24 h (hr) and measured

the diameter of inhibitory zones in mm.