A Review on Green Synthesis of Cu and Cuo Nanomaterials for Multifunctional Applications

H C Ananda Murthy^*1, Buzuayehu Abebe¹, Prakash C H², Kumar Shantaveerayya³

¹Department of Applied Chemistry, School of Applied Natural Science,Adama Science and Technology University, P O Box 1888, Adama, Ethiopia.
²School of Mechanical, Chemical and Materials Engineering,Adama Science and Technology University, P O Box 1888, Adama, Ethiopia.
³School of Civil Engineering and Architecture,Adama Science and Technology University, P O Box 1888, Adama, Ethiopia.

Corresponding Author E-mail: anandkps7@yahoo.com

DOI : http://dx.doi.org/10.13005/msri/150311

ABSTRACT:

Green routes of synthesis are simple, safe, nontoxic and eco-friendly methods to synthesize nanoparticles of various metals and their oxides by the application of bioactive compounds of plants, algae, fungi, yeast, etc. Green engineered copper and copper oxide nanoparticles (Cu and CuO NPs) synthesis has been reported to be more economical and best alternative method among available methods. Cu and CuO NPs have been applied as dietary additives, lubricant supplements, chemical sensors, coating materials in addition to large number of biotechnological and pharmaceuticals applications. The present review aims to bring awareness about various aspects of biogenic synthesis of Cu and its oxide NPs for multifunctional applications and discusses their characterization techniques and applications in antimicrobial activity evaluation, photocatalysis, organic dye degradation, biomedical, pharmaceutical, cosmetic, energy and catalysis.

KEYWORDS: Antimicrobial activity; Catalysis; Cu and CuO NPs; Green synthesis; Multifunctional

Copy the following to cite this article: Murthy H. C. A, Abebe B, Prakash C H , Shantaveerayya K. A Review on Green Synthesis of Cu and Cuo Nanomaterials for Multifunctional Applications. Mat.Sci.Res.India;15(3).

Copy the following to cite this URL: Murthy H. C. A, Abebe B, Prakash C H , Shantaveerayya K. A Review on Green Synthesis of Cu and Cuo Nanomaterials for Multifunctional Applications. Mat.Sci.Res.India;15(3). Available from: http://www.materialsciencejournal.org/?p=12411

Introduction

The research on synthesis and characterization of metallic nanomaterials is an emerging field of nanotechnology due to applications of nanoparticles for scientific, technological, pharmacological and biomedical sectors. Various physical and chemical routes have been employed to synthesize nanoparticles. The chemical method of synthesizing nano particles is extremely costly affair with additional environmental and biological risk. But biogenic synthesis which involves plants for the production of nanoparticles, is a cheap, less costly and environment-friendly method.

Metallic nanoparticles are multifunctional in nature and hence  finds huge number of applications in various sectors for environmental, biomedical and antimicrobial, solar power generation and catalytic causes.¹ Application of plant extracts to synthesize copper and its oxide nanoparticles is a green chemistry methodology which establishes strong relationship between natural plant material and nanosynthesis.²

It has been reported in the earlier works^3,4 that copper, gold and silver nanoparticles exhibited excellent antimicrobial activity against various disease causing pathogens. In recent years, copper nano particles (Cu NPs) have gained significance due to their multifunctional uses in industries and medicine. However, other nanoparticles, such as platinum, gold, iron oxide, silicon oxides and nickel have not shown bactericidal effects in studies with Escherichia coli.⁵ The antibacterial study on E. coli and Bacillus subtilis using Cu and Ag NPs, revealed the fact that Cu exhibited superiority over Ag.⁶ Cu NPs have wide applications as heat transfer systems⁷ antimicrobial materials,⁸ sensors,⁹ and catalysts.¹⁰ In addition, copper and its compound have been applied as antifungal, antiviral, and molluscicidal agents. The synthesis of Cu NPs by using extracts of various plants found all over the globe have been reported by many researchers in the past.^11,12

It is essential to develop clean, reliable, biocompatible, cheap, and nontoxic green method of nanoparticle’s synthesis. Many plants parts or whole plants have been used for the green synthesis of Cu NPs¹³ due to the presence of large number of bioactive compounds in plants. The extracts of plants Nerium oleander,¹⁴ Punica granatum,¹⁵ Aegle marmelos & Ocimum sanctum,^16,17 Zingiber officinale¹⁸ have been efficiently applied for this purpose.

The present review concentrates on biogenic synthetic processes for Cu NPs using extracts of diverse range of plant species including medicinal plants found across the globe and their applications in electronic, magnetic, optoelectronic, biomedical, pharmaceutical, cosmetic, energy and catalysis.

Green Synthesis of Cu and CuO NPs

Plants consists of large number of biologically active compounds and hence, most of the plants have proven record for their anthelmintic, antitumor, antimutagenic, antibacterial and fungicidal properties. The synthesis of metallic NPs involves simple mixing of metal solution with extract of plant. Nanoparticles are produced in the medium due to reduction of metal ions. The reaction to give metallic NPs is as shown in Figure 1.

Many earlier investigations revealed that Cu NPs can be synthesised by the application of most common precursor copper salts namely, cupric acetate (monohydrate) ((CH₃COO)₂Cu·H₂O),¹⁹ Copper chloride di-hydrate (CuCl₂. 2H₂O)²⁰ and Copper sulfate pentahydrate (CuSO₄.5H₂O).²¹ Various factors such as concentration, pH, temperature, influence the nature and properties of synthetic Cu NPs as well as CuO NPs.

Figure 1: A schematic diagram of green synthesis of metal nanoparticles from plant extracts

Click on image to enlarge

The reduction of copper ions to get stable copper nanoparticles can be attributed to the presence of biologically active compounds present in the leaf broth of Azadirachta indica.²² It was found in this study that the rate of production varied linearly with percentage of leaf broth. The other optimum conditions for the synthesis are; [CuCl₂] =7.5 X 10^-3M, pH =6.6 and temperature = 85^oC.

Formation of greenly synthesized copper nanoparticles capped with T. cordifolia (Cu NPs@Tc) was also reported.²³ Synthesis of Cu nanoparticles has been successful with extracts of various parts of plant species that include, Citrus medica Linn. (Idilimbu) juice,²⁴ Ziziphus spina-christi (L.) Willd,²⁵ Asparagus adscendens Roxb. Root and Leaf²⁶, Eclipta prostrata leaves²⁷, Ginkgo biloba Linn,²⁸ Plantago asiatica leaf,²⁹ Thymus vulgaris L,³⁰ black tea leaves,³¹ Terminalia catappa leaf ³² and many more^33-77 presented in table 1.

Table 1: Various plants extracts used in the synthesis of Cu and CuO NPs and their applications.

Click on image to enlarge

In the similar way CuO NPs were also synthesised by using plant extracts of Aloe vera,³³ Oak fruit hull (Jaft),³⁴ Ixoro coccinea leaf,³⁵ Syzygium alternifolium (Wt.) Walp,³⁶ Ferulago angulata (schlecht) boiss,³⁷ Rosa canina fruit,³⁸Azadirachta indica,³⁹ Olea europaea leaf extract,⁴⁰ Malus Domestica leaf extract,⁴¹ Bauhinia tomentosa leaves extract,⁴² Moringa oleifera leaves Extract,⁴⁴ Abutilon indicum leaf extract,⁴⁷ Eclipta prostrata leaves extract,⁴⁸ Euphorbia Chamaesyce leaf extract⁵⁰ and many more as given in Table 1.

Characterization of Cu and CuO NPs

The Characterization of biogenically synthesized Cu and CuO nanoparticles has been carried out by using analytical tools namely, UV-Visible spectroscopy, XRD, EDS, DLS, SEM, TEM, FTIR, HRTEM, particle analyzer, Surface Plasmon resonance etc. The UV–Vis absorption spectroscopy was applied to detect color change in Cu nanoparticle synthesised by using Ziziphus spina-christi leaves²⁵ which is possibly due to the surface plasmon vibrations. The surface plasmon vibration bands for Cu-NPs synthesised by many plant extracts was found to be between 191 nm and 721 nm as given in Table 1.

XRD patterns obtained for the Cu NPs synthesized using citron juice and Aloe vera extract showed intense peak confirming crystalline copper²⁴ and crystalline CuO NPs³³ respectively.

The analysis of FT IR spectra provides information about functional groups of biomolecules present in plant extracts. IR peaks were observed at 3,333 cm^‑1 for the hydroxyl group (H‑bonded OH stretch); 2,917 cm^‑1 for methylene C‑H asym. / sym. stretch; 1,615 cm^‑1 for aromatic ring stretch.²⁷ The peaks at about 3400, 1650, 1595, 1400 and 1100 cm^-1 corresponds to -OH, C=O, C=C, C-OH and C-H vibrations.²⁸ The common IR bands³² for cellulose were usually found at 3304 cm⁻¹,2891 cm⁻¹,1664 cm⁻¹,1011 cm⁻¹ corresponds to vibrations of -OH, CH₂, H₂O, and C-OH groups. Peaks at 610, 499 and 415 cm^-1 confirmed Cu–O bond vibrations that support the presence of monoclinic phases of CuO synthesised by Aloe barbadensis Miller extract.³³ The IR band recorded at about 800 cm^-1 corresponds to C–H out of plane bending vibrations due to adsorbed phenolic compound on to the CuO NPs.³⁴

Electron microscopy is used for morphological characterization and internal composition of biogenic copper and silver nanoparticles. EDS will reveal the elemental composition of the particles.

Homogeneous and spherical morphology of biogenic Cu NPs were revealed by FESEM images. The average particle size varied from 20 nm to 500 nm. TEM micrographs also revealed spherical nature for NPs with least tendency towards agglomeration. DLS studies reveal size distribution of Cu NPs. The average particle size of NPs synthesised by using Azadirachta indica leaves was found to be around 50 nm.²²

The spherical morphology and narrow diameter distributions²⁸ of Cu NPs were also confirmed by TEM images. Biomolecules present in Aloe vera extract³³ believed to act as stabilizing and capping agent for copper caused a raise in the size of NP up to 30 nm but without change in shape.

FESEM images of CuO NPs too confirmed their spherical nature (20 nm to 300 nm). CuO NPs synthesised by Oak fruit extract exhibited average diameter of 34 nm.³⁴ CuO NPs were found to exhibit agglomeration tendency thus enhancing average particle size to as high as 300 nm.³⁵ HRTEM studies involving in-depth analysis of CuO NPs synthesised by using fruit extract of Syzygium alternifolium³⁶ recorded particle size of 2 nm.

CuO NPs synthesised by ferulago angulata ( schlecht ) boiss extract³⁷ revealed shell like sheet structure. CuO NPs with relatively good monodispersed and virtually spherical structures were obtained with size range of 15 to 25 nm without agglomeration.³⁸ TEM analysis of CuO NPs synthesized using B. tomentosa leaf extract⁴² also showed spherical morphology (size of 22 to 40 nm).

Applications of Cu and CuO NPs

Cu and CuO nanoparticles are multifunctional in nature and hence finds significant role in applications that include antimicrobial activities, catalytic degradation, anticancer activity, photocatalytic degradation, antiviral activity, Biofilm formation, nitrates removal, upshot against human pathogens, photoluminescent activities, organic dye degradation catalysis, etc.,

Cu NPs demonstrated good antimicrobial influence on Bacillus spp. and prominent fungicidal influence on Penicillium spp. microorganisms.¹⁹ Cu NPs exhibited greater inhibition on Escherichia coli in comparison with Klebsiella pneumoniae, Pseudomonas aeruginosa, Propionibacterium acnes and Salmonella typhi. Fusarium culmorum was found to establish more sensitive plant pathogenic fungi.²⁶ Cu NPs were also used for antioxidant and cytotoxic activities.²⁷ Cu NPs green engineered by Ginkgo biloba L. leaf extract²⁸ found catalytic application for Huisgen [3 + 2] reaction. Cu- NPs synthesized with Z. spina-christi fruits extract proved to be excellent nanoadsorbent for Crystal Violet removal from aqueous solution.²⁵

Catalytic degradation of basic violet 3 dye in water was successful with CuO NPs obtained by using extract of Oak fruit hull.³⁴ The extract of Rheum palmatum L was also used to synthesize CuO nanoparticles which proved to be efficient catalyst for degradation of 4-nitrophenol, methylene blue rhodamine B and Congo red.⁵³ Effective catalytic application The role of CuO as catalyst can be attributed to high surface to volume ratio associate with large number of active sites. On the same line these particles were found to be photocatalyst^54,61 for Congo red degradation and nanocatalyst for arylation recation.^57,58

CuO NPs synthesised by aqueous extracts of Anthemis nobilis flowers,⁶² Thymus vulgaris L. leaves⁶³ and Euphorbia esula L⁶⁶ were reported to be catalytically active for the synthesis of propargylamines via aldehyde–amine–alkyne (A³) coupling reaction, and Ullmann- coupling reaction respectively. CuO particles synthesized by Saraca indica Leaves exhibited photoluminescence properties.⁶⁴

Aloe vera leaf extract mediated biogenic CuO NPs exhibited the capability to serve as antimicrobial agents against fish bacterial pathogens.⁶⁵

Cu nanoparticles and nanobiocomposites synthesised using plants animal sources found to have potential electronic device applications.⁶⁷ Cu NPs synthesized by using peel extract of Punica granatum⁶⁸ have demonstrated significant antibacterial inhibition against pathogens. In general, large number of plant extracts have been applied towards the green synthesis of Cu and CuO nanoparticles for applications^71-77 such as catalytic, antimicrobial activity (urinary tract), photocatalytic, antioxidant and organic dye degradation.

Conclusions

Green synthesis of metallic and metallic oxide particles has gained great significance in the recent past due to its simplicity, cost effectiveness and environment friendly nature. It has been considered as an alternative method to all existing methods. UV-Visible spectroscopy, XRD, EDS, DLS, SEM, TEM, FTIR, HRTEM, Particle analyzer and Surface Plasmon Resonance are the most applied analytical tools for the characterization of copper and its oxide nanoparticles. Cu and CuO NPs were found to exhibit spherical morphology with size range of 2 – 500 nm depending on concentration of extracts as well as on preparative conditions. Cu and CuO nanoparticles proved to be multifunctional in nature with significant applications with great future implications in the fields of catalysis, photocatalysis, organic dye degradation, cosmetics, biomedicine and pharmaceutics.

Acknowledgements

Authors are great full to the management of Adama Science and Technology University for providing support towards this work.

Funding Source

The author(s) declare(s) that the funding is done by author only.

Conflicts of Interest

The authors declare that they have no conflicts of interest.

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