AU2020102620A4

AU2020102620A4 - A process for synthesis of copper and copper oxide nanostructures

Info

Publication number: AU2020102620A4
Application number: AU2020102620A
Authority: AU
Inventors: Tegene Desalegn; H. C. Ananda Murthy
Original assignee: Desalegn Tegene Dr; Murthy H C Ananda Dr
Current assignee: Desalegn Tegene Dr; Murthy H C Ananda Dr
Priority date: 2020-10-05
Filing date: 2020-10-07
Publication date: 2020-11-26
Anticipated expiration: 2028-10-07

Abstract

A PROCESS FOR SYNTHESIS OF COPPER AND COPPER OXIDE NANOSTRUCTURES The present invention relates to a process for synthesis of copper and copper oxide nanostructures and copper and copper oxide nanostructures obtained therefrom. The process includes the steps of preparing extract of a plant part, blending the plant part extract with a copper containing compound to obtain a blend thereof, incubating the blend for a first predetermined time period and at a first predetermined temperature to obtain an incubated solution thereof containing copper and copper oxide nanostructures, separating the copper and copper oxide nanostructures from the incubated solution to obtain wet copper and copper oxide nanostructures, drying the wet copper and copper oxide nanostructures for a second time period and at a second predetermined temperature to obtain dried copper and copper oxide nanostructures, and pulverizing the dried copper and copper oxide nanostructures to obtain pulverized copper and copper oxide nanostructures. FIG. 5

Description

A PROCESS FOR SYNTHESIS OF COPPER AND COPPER OXIDE NANOSTRUCTURES FIELD OF THE INVENTION

The present invention relates to copper and copper oxide nanostructures. In particular, the present invention relates to a process for synthesis of copper and copper oxide nanostructures and copper and copper oxide nanostructures obtained therefrom.

BACKGROUND OF THE INVENTION

Nanotechnology has become ubiquitous in today's world. Nanotechnology has found several applications in various fields and the applications are increasing.

One such nanostructures are copper and copper oxide nanostructures which have been synthesized in diverse forms such as nanoparticles, nanocrystals, nanorods, nanotubes, nanosheets and have been used in coatings for textiles. Copper and copper oxide nanostructures have been found to exhibit antimicrobial applications.

Attempts have been made in the past and are being made at present to devise new processes or modify the existing processes for synthesizing the nano-particles or nano-structures.

The conventional processes for nano-particles or nano-structures involve numerous chemical compounds and reagents which may be detrimental to humans, and environment. Further, the conventional processes necessitate use of process parameters which are not easy to achieve and are not energy efficient. For example, the conventional processes may include high temperatures or high pressures for synthesis of the nanostructures. Therefore, the conventionally known processes are not environmentally friendly and may also be not economic.

Accordingly, there is an immediate need for providing a process which obviates one or more drawbacks associated with the conventional processes for synthesis of nanostructures or nanoparticles.

OBJECTS OF THE INVENTION

Some of the objects of the presently disclosed invention, of which at the minimum one object is fulfilled by at least one embodiment disclosed herein are as follow:

An object of the present invention is to provide an alternative, which overcomes at least one drawback encountered in the existing prior art;

Another object of the present invention is to provide a process for synthesis of nanostructures;

Still another object of the present invention is to provide a process for synthesis of nanostructures which employ benign chemical compounds and reagents; and

Yet another object of the present invention is to provide a process for synthesis of nanostructures which is eco-friendly green synthesis.

Other objects and benefits of the present invention will be more apparent from the following description which is not intended to bind the scope of the present invention.

SUMMARY OF THE INVENTION

The present disclosure discloses a process for synthesis of copper and copper oxide nanostructures,

The process comprising the steps of preparing extract of a plant part, blending the plant part extract with a copper containing compound to obtain a blend thereof, incubating the blend for a first predetermined time period and at a first predetermined temperature to obtain an incubated solution thereof containing copper and copper oxide nanostructures, separating the copper and copper oxide nanostructures from the incubated solution to obtain wet copper and copper oxide nanostructures, drying the wet copper and copper oxide nanostructures for a second time period and at a second predetermined temperature to obtain dried copper and copper oxide nanostructures, and pulverizing the dried copper and copper oxide nanostructures to obtain pulverized copper and copper oxide nanostructures.

In accordance with one embodiment of the present invention, the plant parts leaves of Artemisia absinthium L.

In accordance with one embodiment of the present invention, the extract of the leaves of Artemisia absinthium L is prepared by washing the leaves of Artemisia absinthium L. with tap water followed by distilled water washing to remove dust and dirt from surface thereof to obtain washed leaves, drying the washed leaves under shadow for a time period ranging from 10 days to 20 days to remove moisture therefrom to obtain dried leaves, pulverizing the dried leaves to obtain a powder thereof and storing the same in an opaque container to prevent exposure thereof to sunlight, mixing a predetermined amount of the powder in deionized water to obtain a mixture thereof, while preventing exposure thereof to sunlight, agitating the mixture using a mechanical shaker for a time period in the range of 50 minutes to 120 minutes at a temperature in the range of 25 °C to 35 °C, wherein the agitation is carried out using a magnetic stirrer to obtain a stirred mixture, allowing the stirred mixture to cool over a time period in the range of 15 hours to 48 hours to obtain a cooled mixture, filtering the cooled mixture to obtain the extract of the leaves and discarding the residue, and storing the extract at a temperature below 5 °C.

In accordance with one embodiment of the present invention, the copper containing compound is copper nitrate, an aqueous Cu(N0 3) 2-3H20 solution is prepared, and is mixed the plant leaf extract gradually in dropwise manner with continuous stirring, the blend is incubated at a temperature in the range of 20 °C to 30 °C for a time period in the range of 600 minutes to 1800 minutes, wherein copper and copper oxide nanostructures are formed in the incubated blend, the incubated blend is centrifuged for 20 minutes and at 8000 rpm to obtain the copper and copper oxide nanostructures, the copper and copper oxide nanostructures are washed with ethanol to remove impurities therefrom to obtained washed copper and copper oxide nanostructures, drying the washed copper and copper oxide nanostructures and pulverizing the dried copper and copper oxide nanostructures to obtain a pulverized powder thereof.

In accordance with one embodiment of the present invention, the first predetermined time period is in the range of 600 minutes to 1800 minutes and the first predetermined temperature is in the range of 20 °C to 30 °C.

In accordance with one embodiment of the present invention, the step of separation is carried out by centrifugation for a time period in the range of 20 °C to 30 °C and at centrifugation speed in the range of 5000 rpm to 10000 rpm.

In accordance with one embodiment of the present invention, the second predetermined time period is in the range of 600 minutes to 1800 minutes and the second predetermined temperature is in the range of 20 °C to 30 °C.

In accordance with one embodiment of the present invention, the copper and copper oxide nanostructures having 20 values of 32.46, 35.52°, 38.730 48.810, 53.42°, 66.09, 67.980, 72.480 and 75.130.

In accordance with one embodiment of the present invention, the copper and copper oxide nanostructures having FTIR peaks at 3375 cm, 1650 cm-, 1405 cn1 and 875 cm and particle size in the range of 14.4 nm and 43.1 nm.

In accordance with one embodiment of the present invention, the copper and copper oxide nanostructures exhibit antibacterial activity against S. aureus,F coli, P. aeruginosa, andF aerogenes.

In accordance with one embodiment of the present invention, the copper and copper oxide nanostructures have a shape selected from the group consisting of prismatic, cylindrical, hexagonal, and triangular.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING

The present invention will now be described with the help of the accompanying drawing, in which:

FIG. la, and FIG. lb illustrate an absorbance spectra of Cu/Cu20/CuO nanostructures after 10 minutes, and 40 minutes of mixing a plant part extract with copper nitrate solution, wherein the Cu/Cu20/CuO nanostructures being synthesized by employing the process of the present invention;

FIG. I illustrates UV-diffuse reflection spectroscopy spectrum Cu/Cu20/CuO nanostructures synthesized by employing the process of the present invention;

FIG. 1d illustrates a Tauc plotof Cu/Cu20/CuO nanostructures synthesized by employing the process of the present invention;

FIG. 2 illustrates an XRD spectrumof Cu/Cu20/CuO nanostructures synthesized by employing the process of the present invention;

FIG. 3 illustrates a Fourier Transform Infrared (FTIR) Spectra of Artemisia absinthium L. plant extract and Cu/Cu20/CuO nanostructures synthesized by employing the process of the present invention;

FIG. 4a and FIG. 4b illustrate scanning electron microscope images of Cu/Cu20/CuO nanostructures synthesized by employing the process of the present invention;

FIG. 4c illustrates an Energy dispersive X-ray spectrum of Cu/Cu20/CuO nanostructures synthesized by employing the process of the present invention;

FIG. 5a illustrates Transmission Electron Microscope micrograph of Cu/Cu20/CuO nanostructures synthesized by employing the process of the present invention at 100 nm magnification;

FIG. 5b illustrates Transmission Electron Microscope micrograph of Cu/Cu20/CuO nanostructures synthesized by employing the process of the present invention at 50 nm magnification;

FIG. 5c illustrates a Selected Area Electron Diffraction (SAED) pattern of Cu/Cu20/CuO nanostructures synthesized by employing the process of the present invention;

FIG. 5d illustrates a high-resolution transmission electron microscopy micrograph of lattice fringes of VeA-Cu/Cu 20/CuO nanostructures with IPS value of 0.2395 nm, the Cu/Cu20/CuO nanostructures being synthesized by employing the process of the present invention at 50 nm magnification;

FIG. 6a illustrates a high-resolution transmission electron microscopy micrograph of Cu/Cu20/CuO nanostructures synthesized by employing the process of the present invention with enhanced lattice fringes;

FIG. 6b illustrates a high-resolution transmission electron microscopy micrograph IFFT pattern of Cu/Cu20/CuO nanostructures synthesized by employing the process of the present invention;

FIG. 6c illustrates a profile of IFFT with IPS value of Cu/Cu20/CuO nanostructures synthesized by employing the process of the present invention;

FIG. 7a, FIG. 7b, FIG. 7c, and FIG. 7d illustrates images depicting antibacterial activity of copper and copper oxide nanostructures against S. aureus, F coli, P. aeruginosaandF aerogenes respectively.

DETAILED DESCRIPTION

All the terms and expressions, which may be technical, scientific, or otherwise, as used in the present invention have the same meaning as understood by a person having ordinary skill in the art to which the present invention belongs, unless and otherwise explicitly specified.

In the present specification, and the claims, the articles "a", "an", and "the" include plural references unless the context clearly dictates otherwise.

The term "comprising" as used in the present specification and the claims will be understood to mean that the list following is non-exhaustive and may or may not include any other extra suitable features or elements or steps or constituents as applicable.

Further, the terms "about" or "approximately" used in combination with ranges relating to sizes of parts, or any other physical properties or characteristics, are meant to include small variations that may occur in the upper and/or lower limits of the ranges of the sizes.

The present invention discloses a process for synthesis of copper and copper oxide nanostructures or nanoparticles. The words "nanostructures" and "nanoparticles" are used herein to mean copper and copper oxide particles having a size in the nanometre range. Further, the term copper oxide includes Cu20, CuO and a combination thereof.

The present invention though described herein with reference to copper and copper oxide nanostructures, the process of the present invention can be equally applied to synthesis of any other nanostructures and is not limited to copper and copper oxide nanostructures.

In accordance with the present invention a process for synthesis of copper and copper oxide nanostructures is disclosed. The process for synthesis of copper and copper oxide nanostructures comprises the following steps, which are described in detail herein below.

In the first step, a plant part is provided and an aqueous extract of a plant part is prepared. In accordance with the present invention, the plant is Artemisia absinthium L. and the leaves of Artemisia absinthium L. are employed.

The extract of the leaves of Artemisia absinthium L. is prepared by firstly washing the leaves of Artemisia absinthium L. with tap water followed by distilled water washing to remove dust and dirt from surface thereof. The step of washing can be repeated one or more times to ensure complete removal of dust and dirt from the surface of the leaves. The cleaned or washed leaves are further processed.

The washed leaves are dried. The step of drying the washed leaves is performed under shadow for a time period ranging from 10 days to 20 days to remove moisture therefrom and obtain dried leaves. In one embodiment the time period is 15 days.

The dried leaves so obtained are then pulverized to obtained a powder of the dried leaves. The leaves may be pulverized manually or by using a pulveriser. The powder so obtained is stored in an opaque container to prevent exposure thereof to sunlight.

Further, when preparing the aqueous solution of the plant part extract, a predetermined amount of the powder is mixed in a predetermined quantity of deionized water to obtain a mixture thereof, while preventing exposure thereof to sunlight.

The mixture so obtained is agitating using a mechanical shaker for a time period in the range of 50 minutes to 120 minutes at a temperature in the range of 25 °C to 35

°C, wherein the agitation is carried out using a magnetic stirrer to obtain a stirred homogeneous mixture of the plant part in the deionized water.

The stirred mixture is allowed to cool a time period in the range of 15 hours to 48 hours to obtain a cooled mixture. In one embodiment the time period is 24 hours. The cooled mixture is then filtered to obtain the extract of the leaves and the residue is discarded. The extract so obtained is stored in an opaque container at a temperature below 5 °C. In one embodiment the temperature is 4 °C

The so obtained plant part extract is blended in appropriate proportion with a copper containing compound to obtain a blend thereof. In one embodiment of the present invention, the copper containing compound is copper nitrate (Cu(N0 3) 2-3H20). The copper containing compound (Cu(N0 3) 2-3H20) is blended with the plant extract in the form of an aqueous Cu(N3)2-3H20 solution, wherein the aqueous solution of Cu(N0 3) 2-3H20 is added to the plant extract in dropwise manner with continuous manner.

The blend is incubated for a first predetermined time period and at a first predetermined temperature to obtain an incubated solution thereof containing copper and copper oxide nanostructures.

In accordance with one embodiment of the present invention, the first predetermined time period is in the range of 600 minutes to 1800 minutes and said first predetermined temperature is in the range of 20 °C to 30 °C.

Further, the copper and copper oxide nanostructures are separated from the incubated solution to obtain wet copper and copper oxide nanostructures. The step of separation is carried out by centrifugation. The centrifugation is carried out for a time period in the range of 10 minutes to 60 minutes. In one embodiment the time period is 20 minutes. The centrifugation speed is in the range of 5000 rpm to 10000 rpm. In one embodiment the centrifugation speed is 8000 rpm.

The so obtained wet copper and copper oxide nanostructures are then dried for a second time period and at a second predetermined temperature to obtain dried copper and copper oxide nanostructures. The second predetermined time period is in the range of 600 minutes to 1800 minutes and said second predetermined temperature is in the range of 20 °C to 30 °C. In one embodiment the second predetermined time period is 720 minutes and the second predetermined temperature is 25 °C.

Further, the dried copper and copper oxide nanostructures are pulverised to obtain pulverized copper and copper oxide nanostructures.

In one embodiment, the copper and copper oxide nanostructures are then washed with ethanol to remove impurities therefrom to obtained washed copper and copper oxide nanostructures before the step of drawing.

In accordance with one embodiment of the present invention, the copper and copper oxide nanostructures have 20 values of 32.46, 35.520, 38.730 48.810,

53.42°, 66.09, 67.98°, 72.48° and 75.13.

In accordance with one embodiment of the present invention, the copper and copper oxide nanostructures having FTIR peaks at 3375 cm-, 1650 cm-', 1405 cm-' and 875 cm-' and particle size in the range of 14.4 nm and 43.1 nm.

The present invention is now described with reference to the following examples, wherein the examples are provided for a clear understanding of the process of the present invention and not for limiting the scope thereof.

Examples:

Example 1 ( In accordance with the embodiment of the present invention):

Synthesis of copper and copper oxide nanostructures by using the process of the present invention.

Step 1: Preparing an aqueous extract of a plant part.

Artemisia absinthium L. plant leaves were collected from the agricultural plots of Wondo Genet Agricultural Research Centre, Oromia, Ethiopia.

The leaves of Artemisia absinthium L. taken and washed with tap water first and the with distilled water to remove dirt and dust from the surface of the leaves. The washed leaves were dried in shadow for 15 days at 25 °C to remove moisture from the washed leaves. The dried leaves were pulverized to obtain a powder, which was stored in an opaque container to prevent exposure thereof to sunlight. The dried leaves were ground using a grinding machine followed by packing in a brown bottle. The extraction was carried out by taking 20 g of powdered leaves of Artemisia absinthium L. in a 500 ml of conical flask containing 400 ml of deionized water. The flask was later covered with aluminium foil, to prevent the effect of light. After that the mixture was shaken using mechanical shaker for 90 minutes and allowed to warm at 30 °C for 1 hour on magnetic stirrer, then it was allowed to cool down to room temperature overnight. The prepared solution was filtered through Whatman No. 1 filter paper to get clear solution. The filtrate was stored at 4 °C for future experiments.

Step 2: Blending of leaf extract with copper containing compound:

100 mL of the leaf extract was blended with Cu (N0 3) 2-3H20 (400 mL of 0.5 M solution) in a 500 mL flask to obtain a blend thereof.

Step 3: Blend incubation:

The blend so obtained was incubated for 24 hours at room temperature (25 °C) to obtain brownish coloured liquid.

Step 4: Separation:

The obtained brownish coloured liquid was centrifuged for 30 minutes at 8000 rpm to get dark brownish Cu/Cu20/CuO nanostructures which are wet.

Step 5: Washing and drying:

These Cu/Cu20/CuO nanostructures were washed, and dried. The drying was carried out for a time period of about 1200 minutes and at 25 °C.

Step 6: Pulverizing:

The washed and dried copper and copper oxide nanostructures were pulverized to obtain pulverized copper and copper oxide nanostructures, which were stored for further use.

Characterization of the copper and copper oxide nanostructures:

The copper and copper oxide nanostructures were characterized by UV visible spectrometer, X-ray diffraction, FTIR spectroscopy, scanning electron microscopy, transmission electron microscopy, SAED, and HRTEM. The characterization results are listed herein below and figures (FIG. 1 to FIG. 6).

UV-visible absorbance spectrum:

The UV-visible absorbance spectrum of the Cu/Cu20/CuO nanostructures revealed Xmax of 411 nm as shown in FIG. la, just after 10 minutes of mixing the plant extract with the copper nitrate solution.

The absorbance spectrum recorded after 40 minutes of forming homogeneous mixture, exhibited 2 maxima, oneimax at 438 nm and the other atmax of 451 nm (FIG. lb).

The splitting of absorbance band into two, clearly affirm the formation of more than one type of nanostructures. The presence of two maxima clearly substantiates a mixture of copper and its oxides nanostructures.

It is anticipated that initially Cu nanostructures formed resulted in a single band withimax of 411 nm. But at later stage, Cu is found to react slowly and oxidize to Cu20 and CuO. This is responsible for the presence of 2 maxima in the spectrum after 40 minutes of beginning of synthesis process of nanostructures.

The UV-visible-DRS spectrum was recorded (FIG. ic) for nanostructures. The Tauc plot (FIG. 1d) was utilized to compute the band gap energy of Cu/Cu20/CuO nanostructures with the assistance of Kubelka-Munk function. The energy gap (Eg) of 2.11 eV was deduced for Cu/Cu20/CuO nanostructures.

X-ray diffraction:

The XRD analysis was executed to explore the in-depth details of the crystal structure of VeA-Cu/Cu 20/CuO nanostructures. The XRD spectrum of

Cu/Cu2 0/CuO nanostructures (FIG. 2) demonstrates a total of 11 prominent peaks. Among them, three of the peaks with 20 values of 38.73°, 66.090 and 72.48 conform to 111, 220 and 311 crystal lattice planes of copper (fee structure) and the diffraction data is in compliance with the data of ICSD card No. 004-0836.

Further, a few peaks appeared at 20 values of 38.73 and 61.53 conform to 111 and 220 crystallographic planes of Cu20 nanostructures (ICSD file No. 05-0667, cuprite- Pn-3m). The other peaks at 20 values of 32.46, 35.52°, 38.73 48.81, 53.42°, 67.980 and 75.13° correlates to 110, 002, 111, 202. 020, 220 and 400 planes of CuO (fec) (ICSD card No. 048-1548, Tenorite). The main draw back in the environment friendly biosynthesis of copper nanostructures is their rapid oxidation in air to yield a mixture of Cu20 and CuO.

FTIR analysis:

The FTIR spectroscopy was helpful in revealing the bonding features of both leaf extract and Cu/Cu20/CuO nanostructures. The intense peaks shown in Fig. 3, respectively at 3375 cm-1 and 1262 cm-1 corresponds to phenolic -OH stretching and bending vibrational frequencies. The peak at 1650 cm- 1arises due to C=0 vibration of ketonic groups. The small peak at 2925 cm-' was correlated to the alkane C-H stretching mode. The vibration of -COO group of carboxylic acid was found to appear at 1405 cm-1 .

1 A less intense band at around 875 cm- confirms the presence of glycosidic linkage. An intense peak at 615 cm-1 substantiates the formation of CuO and its stretching. The presence of prominent peaks at 3375 cm- 1, 1650 cm-', 1405 cm '

and 875 cm-1 in the FTIR spectra of both plant extract and nanostructures, clearly indicate the presence of bioactive molecules around the nanostructures. These bioactive molecules had been confirmed to have performed a sizable function in the nucleation and growth of Cu/Cu20/CuO Nanostructures.

The C-O-C vibration displays at 1068 cm-1 . The bending vibrations of Cu-O-H bonds resulted in a small peak at 896 cm' which is possibly due to Cu-O bond. A peak at 615 cm-1 correlates to bending vibrations of C-H bond. FTIR spectral inspection confirmed the presence of phytochemicals in the leaf extract and their roles as reducing agent and stabilizing agent during the synthesis of Cu/Cu20/CuOnanostructures.

Electron microscope analysis:

The SEM micrographs of nanostructures are presented as FIG. 4a and FIG. 4b which clearly depict a variety of nanostructures in terms of their diverse shapes and sizes.

The Cu/Cu20/CuO nanostructures had average diameters of 20 nm. The presence of mixed type of nanostructures is possibly due to the nature and amounts of capping agents around the particles.

EDAX analysis revealed the elemental composition of the Cu/Cu20/CuO nanostructures as depicted in FIG. 4c. The elements, Cu, C and 0 have been identified in the spectrum signifying the purity of the nanostructures. The presence of elements, C and 0 is most possibly due to bioactive compounds. In addition, it is also apprehended that copper present at the surface had been converted into CuO and Cu20.

HRTEM analysis:

The HRTEM images as shown in FIG. 5 affirms that the Cu/Cu20/CuO nanostructures are mostly spherical but also with regular as well as irregular geometries. This is possibly due to the dual role (Reduce and stabilize) played by the bioactive molecules of Artemisia absinthium L. leaf extract. The existence of nanosized particles of the dimension, 14.4 nm substantiate the efficient role of bioactive components of the extract as capping and stabilizing agents otherwise agglomerated particles would have formed.

FIG. 5a to 5d shows the TEM imagesof Cu/Cu20/CuO nanostructures. A mixture of diversely shaped particles including cylindrical, hexagonal, triangular shapes were found in these images.

The almost spherical structures with the size ranging from 14.4 nm to 43.1 nm with a median particle size of 34.76 nm are as shown in FIG. 5a and 5b.

The six spots appeared on the SAED pattern, were correlated to specific crystal planes of Cu/Cu20/CuO nanostructures as shown in FIG. 5c. One of such planes is presented with interplanar spacing (IPS) value of 0.2395 nm in FIG. 5d.

The FIG. 6a, FIG. 6b, and FIG. 6c illustrates the HRTEM micrographs with Cu/Cu20/CuO nanostructures with enhanced lattice fringes, IFFT and profile of IFFT with IPS value for a specified plane, respectively. The IPS value for a specific parallel crystal planes on the surface of Cu nanostructures was deduced to be 0.2444 nm.

Table 1 provides the IPS values for the 6 spots appeared on the SAED pattern (FIG. 5c) of Cu/Cu20/CuO nanostructures. Each spot on the SAED pattern corresponds to specific set of lattice planes. The IPS values of 0.2854 nm, 0.2432 nm, 0.2271 nm, 0.2040 nm, 0.1491 nm and 0.1261 nm, derived for spot I to spot 6 corresponding to crystal planes, -111(CuO), 111(Cu2O), 200(Cu) 111(Cu), 111(Cu20) and 220(Cu) are in accordance with the IPS values of CuO, Cu20 and Cu structures.

TABLE 1

Spot Interplanar spacing Rec. Pos. Degrees to Amplitude No. (nm) (1/nm) Spot 1

1 0.2854 3.504 0.00 284.20

2 0.2432 4.112 11.68 1093.93

3 0.2271 4.404 9.20 612.11

4 0.2040 4.903 30.11 178.68

5 0.1491 6.707 5.14 316.22

6 0.1261 7.928 15.73 440.04

This SAED-HRTEM analysis exhibited results which are in concurrence with XRD results for the Cu/Cu20/CuO nanostructures. The IPS value of lattice fringes at the surface of the Cu/Cu20/CuO Nanostructures was found to be 0.2444 nm, which is like the dhkl value of 0.24 nm for (111) plane of fee structured Cu20. This corroborates that the surface copper atoms of Nanostructures would have reacted with air to form their respective oxides, Cu20 and CuO.

Antimicrobial activity:

Agar disc-diffusion method was adopted for the evaluation of in-vitro antibacterial properties of VeA-Cu/Cu2 0/CuO nanostructures against S. aureus,

. coli, P. aeruginosa,andF aerogenes.

Effectively grown bacterial cultures were dispersed on Mueller-Hinton Agar (MHA) plate (turbidity was adjusted with Tryptone Soy Broth, TSB to match 0.5 McFarland standard).

The extract of the copper and copper nanostructures was prepared with four different concentrations in Dimethyl Sulfoxide. Four concentrations (6.25, 12.5, 25 and 50 pg/pl) of the synthesized nanostructures were added to the respectively labelled wells.

The antibiotic discs of 6 mm diameter were applied to agar surface using forceps with gentle pressure and then impregnated with the dissolved extract. The positive and negative controls taken were Chloramphenicol and DMSO, respectively. The plates were incubated at 35± 2 C in an ambient air incubator for 18-24 hours. The zone of inhibition was measured to the nearest millimetres (mm) using a ruler and recorded for all the samples.

The zone of inhibitions for Chloramphenicol, DMSO and Nanostructures with four concentrations (6.25, 12.5, 25 and 50 pg/pl) are as shown in FIG. 7. VeA Cu/Cu20/CuO nanostructures were found to show better antimicrobial activity against E. aerogenes (Gram negative bacteria) than Gram positive bacteria which could be attributed to the structural differences in the cell walls of bacteria.

The antimicrobial activity of nanostructures was highly appreciable against E. aerogenes.

TECHNICAL ADVANCES AND ADVANTAGES OF THE INVENTION

The presently disclosed invention, as described herein above, provides several technical advances and advantages including, but not limited to, a process for synthesis of copper and copper oxide nanostructures, wherein the process is:

- Eco-friendly;

- Employs benign chemical compounds and reagents;

- Simple; and

- Economic.

Claims

We claim:

1. A process for synthesis of copper and copper oxide nanostructures, said process characterized by having:

- preparing an aqueous extract of a plant part;

- blending said plant part extract with a copper containing compound to obtain a blend thereof;

- incubating said blend for a first predetermined time period and at a first

predetermined temperature to obtain an incubated solution thereof containing copper and copper oxide nanostructures;

- separating said copper and copper oxide nanostructures from said incubated solution to obtain wet copper and copper oxide nanostructures;

- drying said wet copper and copper oxide nanostructures for a second time period and at a second predetermined temperature to obtain dried copper and copper oxide nanostructures; and

- pulverizing said dried copper and copper oxide nanostructures to obtain pulverized copper and copper oxide nanostructures.

2. The process as claimed in claim 1, wherein said plant parts are leaves of Artemisia absinthium L.

3. The process as claimed in claim 2, wherein said extract of said leaves of Artemisia absinthium L is prepared by the following sub-steps:

- washing said leaves of Artemisia absinthium L. with tap water followed by distilled water washing to remove dust and dirt from surface thereof and obtain washed leaves;

- drying said washed leaves under shadow for a time period ranging from 10 days to 20 days to remove moisture therefrom to obtain dried leaves;

- pulverizing the dried leaves to obtain a powder thereof and storing the same in an opaque container to prevent exposure thereof to sunlight;

- mixing a predetermined amount of the powder in deionized water to obtain a mixture thereof, while preventing exposure thereof to sunlight;

- agitating said mixture using a mechanical shaker for a time period in the range of 50 minutes to 120 minutes at a temperature in the range of 25 °C to 35 °C, wherein the agitation is carried out using a magnetic stirrer to obtain a stirred mixture;

- allowing said stirred mixture to cool over a time period in the range of 15 hours to 48 hours to obtain a cooled mixture;

- filtering said cooled mixture to obtain the extract of the leaves and discarding the residue; and

- storing said extract at a temperature below 5 °C.

4. The process as claimed in claim 1, wherein

- said copper containing compound is copper nitrate;

- an aqueous Cu(N03)2-3H20 solution is prepared, and is mixed said plant leaf extract gradually in dropwise manner with continuous stirring;

- said blend is incubated at a temperature in the range of 20 °C to 30 °C for a time period in the range of 600 minutes to 1800 minutes, wherein copper and copper oxide nanostructures are formed in said incubated blend;

- said incubated blend is centrifuged for 20 minutes and at 8000 rpm to obtain said copper and copper oxide nanostructures;

- said copper and copper oxide nanostructures are washed with ethanol to remove impurities therefrom to obtained washed copper and copper oxide nanostructures; and

- drying said washed copper and copper oxide nanostructures and pulverizing said dried copper and copper oxide nanostructures to obtain a pulverized powder thereof.

5. The process as claimed in claim 1, wherein

- said first predetermined time period is in the range of 600 minutes to 1800

minutes and said first predetermined temperature is in the range of 20 °C to

30 °C;

- said step of separation is carried out by centrifugation for a time period in the range of 20 °C to 30 °C and at centrifugation speed in the range of 5000 rpm to 10000 rpm;

- said second predetermined time period is in the range of 600 minutes to 1800 minutes and said second predetermined temperature is in the range of 20 °C

to 30 °C;

- said copper and copper oxide nanostructures having 20 values of 32.460, 35.520, 38.730 48.810, 53.420, 66.090, 67.980, 72.480 and 75.130;

- said copper and copper oxide nanostructures having FTIR peaks at 3375 cm 1, 1650 cm-, 1405 cm-' and 875 cm-1 and particle size in the range of 14.4 nm and 43.1 nm;

- said copper and copper oxide nanostructures exhibit antibacterail activity against S. aureus, F coli, P. aeruginosa, andF aerogenes; and

- said copper and copper oxide nanostructures have a shape selected from the group consisting of prismatic, cylindrical, hexagonal, and triangular.