Ocimum Sanctum Leaf Extract Research Articles

Antimicrobial Effect of Silver Nanoparticles Synthesised with Ocimum Sanctum Leaf Extract on Periodontal Pathogens

Antimicrobial Effect of Silver Nanoparticles Synthesised with Ocimum Sanctum Leaf Extract on Periodontal Pathogens

Efficacy of botanical formulations and fungicides against Botryosphaeria dothidea, causing white rot in apple (Malus × domestica Borkh.)

The present study was conducted to determine inhibitory effect of plant extracts, their botanical formula-tions (BF1 and BF2) and safer fungicides against Botryosphaeria dothidea cause white rot of apple (Malus × domes-tica) during storage. Poisoned food technique was performed to evaluate the efficacy of different plant extracts, their botanical formulations and safer fungicides. Out of twelve botanicals evaluated under in vitro conditions against the white rot pathogen, leaf extract of Ocimum sanctum was found most effective among all the treatments with 54.07 per cent average inhibition in mycelial growth. Out of twelve plants evaluated for their efficacy, six effective plants Karu (Roylea elegans), Artemisia (Artemisia roxburghiana), Neem (Azadirachta indica), Bana (Vitex negundo), Tulsi (Ocimum sanctum) and Darek (Melia azedarach) were selected for making two botanical formulations (BF1 and BF2). While, BF1 was water based formulation and BF2 was cow urine based formulation. Among these botanical formulations, BF2 inhibited mycelial growth of white rot pathogen by 72.70 per cent and BF1 66.37 per cent at 100 % concentration. Whereas, among the tested fungicides, Score at 100 ppm concentration was found to be most effective with 75.01 % average inhibition in mycelial growth of the white rot pathogen.

Anti Escherichia Coli Activity of Some Medicinal Plants of High Altitude of Nepal

Background: Plants and plant-based medicaments are the basis of many of the modern pharmaceuticals we use today for our various ailments. The aim of the present study was to find out the bioactive chemical constituents such as flavonoids, alkaloids, tannins, saponins, carbohydrate and to find out the anti E. coli activity of the ethanolic extracts of traditionally used ten medicinal plants of Nepal at an altitude of 1500 ft from above the sea level.Methods: Ethanolic extracts of ten commonly used medicinal plants were analyzed phytochemically and evaluated for their significant antimicrobial activity against the clinical isolates of Escherichia coli. Mean zones of inhibition were calculated for each of the extracts.Results: The results revealed that though all the plants of the high altitude showed some degree of antimicrobial activity, the leaf extract of Syzygium cumini (5.7±0.3 cm), Chromolaena odorata (5.2±0.4 cm), Ocimum sanctum (4.7±0.6 cm) and Justicia adhatoda (3.2±0.3 cm) were most effective against the clinical isolates of E. coli, whereas the other six plant extracts were least effective against the clinical isolates of E. coli. Qualitative phytochemical analysis of the extracts revealed the presence of bioactive components. Seven of the plant extracts contain alkaloids, six of them contain glycosides, four of them contain flavonoids, three of them contain carbohydrate, oil and fats, two of them contain tannins, whereas only one of them contains saponins.Conclusion: The result of this study justified the folkloric usage of the studied plants and concluded that these plants extract have great potential in finding new clinically effective antimicrobial compounds.MED Phoenix Volume (1), Issue (1) July 2016, page: 3-9

Zeolites-AuNPs assembled interface towards amperometric biosensing of spermidine

Detection of the spermidine level (Spmd) present in a sample is a sensible indication of the standard of foodstuffs. A new biosensing electrode having polyamine oxidase (PAO) as the biorecognition element immobilized on the surface of chitosan (CHIT)/zeolites-gold nanoparticles (AuNPs) modified gold (Au) electrode was prepared and applied for determination of Spmd contents in fish homogenates. Zeolite nanocrystals and AuNPs were synthesized via hydrothermal and biological (using Ocimum sanctum leaf extracts) routes respectively and hybrids of zeolites-AuNPs were synthesized by high temperature calcination. Transmission Electron Microscopy (TEM) was used to determine the size of AuNPs and their efficient impregnation onto zeolites was confirmed by Energy Dispersive X-ray (EDX) Spectroscopy studies. Thus synthesized zeolites-AuNPs hybrids, when used with chitosan (CHIT/zeolites-AuNPs), offered a porous structure with high surface area having an activated surface for attaching. This retains the enzyme along with better electron transport properties. Electrochemical Impedance Spectroscopy (EIS) and Scanning Electron Microscopy (SEM) were used to confirm the modification of Au electrode with PAO loaded CHIT/zeolites-AuNPs composite film. Cyclic voltammetry (CV) was used to study the activity of the immobilized PAO electrochemically. Under optimum conditions, the proposed electrochemical sensor showed wide linearity ranging from 0.2–200μM and a detection limit (LOD) of 0.1μM (S/N=3) with favorable reproducibility and stability.

Synergistic anticancer effect of green synthesized nickel nanoparticles and quercetin extracted from Ocimum sanctum leaf extract

Leaf extract of medicinally important plant Ocimum sanctum (O. sanctum) has been used for the synthesis of nickel nanoparticles (NiGs) and extraction of quercetin (Qu). Qu has been conjugated with NiGs for enhanced anticancer effect on human breast cancer MCF–7 cells. Extracted Qu was conjugated with polyethylene glycol (PEG) coated NiGs (Qu–PEG–NiGs) which was used as carriers for breast cancer treatment. Anticancer activity of Qu–PEG–NiGs was evaluated by assessing cell viability, reactive oxygen species (ROS) production, caspase activity, mitochondrial membrane potential (MMP) and changes in nuclear morphology (staining methods). 0.85mg of quercetin was extracted from 1g of leaves with retention time (Rt) of 2.914min. Loading and encapsulation efficiency of quercetin onto PEG–NiGs was 15.04% and 82% respectively and Qu–PEG–NiGs has shown a sustained release of Qu of about 84% after 48h. Qu and Qu–PEG–NiGs showed dose dependent (1.56–50μg/mL) anticancer effect against MCF–7 cells with IC50 values of 50 and 6.25μg/mL respectively which was mediated by oxidative stress due to ROS over-production that induced loss of mitochondrial membrane potential, capsase -9, -7 activities leading to apoptosis. The present study validates that Qu–PEG–NiGs can be used as a potential anticancer agent for cancer therapy.

Biologically Synthesized Gold Nanoparticles using Ocimum sanctum (Tulsi Leaf Extract) Induced Anti-Tumor Response in a T Cell Daltons Lymphoma

The characterizations of green synthesized gold nanoparticles (AuNPs) prepared using Ocimum sanctum leaf extract were done by UV-Spectrophotometer at 500-540 nm. The XRD data obtained were found similar to gold JCPDS File No- 04-0784. SEM and TEM analysis of AuNPs revealed spherical shape and size of 200 nm. Further FT-IR data indicated the various biomolecules present in Ocimum sanctum leaf extract provides stability to gold nanoparticles synthesis. The AuNPs were studied for their anti-cancer activity on Dalton’s lymphoma (DL) cells and the results obtained with IC50 value of < 50 ng/ml performed by MTT assay. Further, to confirm anti-tumor potential and the mode of action of the synthesized AuNPs, cell viability assay, nuclear morphology, DNA fragmentation assay, mitochondrial membrane potential (ΔΨm) analysis, and cell cycle analysis were done using DL cells. DL cells treated with the AuNPs showed reduced cell viability, altered nuclear morphology, typical apoptotic DNA ladder formation and apoptosis. From the above finding it can be concluded that the AuNPs have potential to decrease the proliferation of tumor cells and enhanced the production of ROS. Gold nanoparticles used in cancer detection and diagnosis/treatment are mainly in preclinical stages of cancer development.

Biosynthesis of PVA encapsulated silver nanoparticles

Green synthesis of metal nanoparticles is an important technique in the methods of eco-friendly nanoparticle production. The synthesis of silver nanoparticles was accomplished using Ocimum sanctum leaf extract at room temperature. These particles were then encapsulated with polyvinyl alcohol (PVA) polymer matrix. The presence of silver was confirmed by different characterization techniques such as UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR) and X-Ray Diffraction (XRD). Scanning electron microscopic (SEM) images of the synthesized powder shows spherical shaped silver nanoparticles embedded in sponge-like polymer matrix. The energy dispersive X-ray analysis confirms the presence of elemental silver along with iron signal. Energy dispersive signal corresponding to elemental iron has been attributed to O. sanctum plant. The silver nanoparticles in PVA matrix thus obtained shows high antibacterial activity against gram positive Staphylococcus aureus (S. aureus) and gram negative Escherichia coli (E. coli) water borne bacteria. The inhibition zone against S. aureus and E. coli were also calculated.

Antimicrobial activity of leaf extract of Ocimum sanctum on various clinical isolates

Medicinal properties are present in different part s of Ocimum sps. like leaves flowers, root, stem etc. and have been used by traditional medical practitio ners. The aim of this study was to determine the antimicrobial activity of cold and hot water extrac t of leaves of Ocimum sanctum against clinical bacterial isolates by disc diffusion method. Cold a nd hot water extract of leaf of Ocimum sanctum were prepared at 250µg/ml, 500µg/ml, 1000µg/ml concentrations, impregnated into discs of 6mm diameter and tested on S.aureus , B.subtilis, E.coli , Proteus mirabilis , Shigella dysentriae , Salmonella typhimurium . There was no significant difference between the zo ne of inhibition of the test organisms to cold and hot water extracts. S. aureus and S. typhimurium had the zone size of 1.2 cm, 1.1 cm and 1.0 cm zone of inhibition for B. subtilis and Shigella dysentriae respectively. The inhibition was the greatest at concentration of 1000 µg/ml for both co ld and hot water extracts against all test organism s. The antimicrobial activity was the maximum for E. coli i.e. 1.4 cm in both cold and hot water extracts. The antimicrobial susceptibility pattern of leaf ex tract of Ocimum sanctum was found to be more or less active against all tested pathogenic strains f or both cold and hot water extracts; it may be due to the presence of tannins, essential oils, flavonoids , alkaloids and eugenol present in varying proportions. The plant contains important bio-activ e compounds and hence has found use as essential plant species in traditional medicine for treatment of various diseases.

Bio-synthesis of Silver Nano-prisms from Ocimum sanctum manipulation of Localised surface Plasmon through induced resonance

Localised surface Plasmon Resonance (LSPR) is a phenomenon in its starting stages that is being put through study for its sensing applications. With the rise of a new innovation comes the lack of considerations for the environment and this has been established by the many centuries of industrial revolution all around the world. This work was initiated as an attempt to produce optically configured Silver Nano-prisms through Eco-Friendly methodology and as an investigation to find an alternative to the traditional. Ocimum sanctum leaf extract was utilised for the traditional precipitation-stabilization biosynthetic method for its ease and efficiency. Preliminary analyses conducted, production of Silver Nano particles were characterised. This was achieved by mixing 2.5 ml of extract in AgNO3 to arrive at the same. A characteristic change in colour was observed towards an amber-brown from milky white to indicate the formation of silver Nano-particles. A clear absorbance peak at around 410 nm indicating the presence of silver Nano-particles . Now the resultant solution was exposed to varying optical condition to manipulate its Surface Plasmon and preliminary analyses showed obvious changes in optical and physical properties of the Nano-particles. These Nano-Prisms were characterised by a change in the entire particulate structure that gave it a triangular, pyramidal shape . These changes were analysed and discussed after various tests and imaging processes.

Study of Antimicrobial Properties of Fabrics Treated with Ocimum Sanctum L (tulsi) Extract as a Natural Active Agent

ABSTRACTThe present study was aimed at development of microbial resistant textile product using a natural bioactive agent. Ocimum sanctum leaf extract was applied on cotton and polyester/cotton blended fabrics for imparting antibacterial properties to the textile product for health care applications. The fabrics were treated with herbal extract of different concentrations, along with glutaraldehyde as cross-linking agent and sodium hypophosphite as catalyst by exhaust method. Antimicrobial assessment was performed quantitatively by percentage reduction test (AATCC-147-1998) against test organisms gram-positive bacteria staphylococcus aureus (ATCC 6538) and gram-negative bacteria Escherichia coli (ATCC 11230). The results provided evidence that the treated fabric inhibited the growth of gram-positive bacteria by more than 92% as compared to the control samples. Gas chromatography mass spectrometry analysis confirmed the presence of eugenol in Ocimum sanctum extract. Although, the treated fabrics showed enhanced crease recovery property, there was a marginal reduction in tensile properties. Improvement in crease recovery property of treated blended fabric was slightly less as compared to treated cotton fabric. The antimicrobial treatment negatively affects the bending properties and this negative effect was found to be slightly less for blended fabric as compared to pure cotton fabric.

Reversible Anti-Fertility Effects of Aqueous Leaf Extract of Ocimum Sanctum (Linn.) in Male Mice

Present study was undertaken to evaluate the reversible anti-fertility effect of Ocimum sanctum Linn (Tulsi) on male mice. Aqueous leaf extract of Ocimum sanctum was orally administered (0.1ml) for 10 (P < 0.05), 20 (P < 0.01), 30 (P < 0.001), 40 (P < 0.001) and 50 (P < 0.001) days of exposure. Treatment of aqueous leaf extract of Ocimum sanctum showed significant decrease in sperm counts during 10 (P<0.1), 20 (P<0.01), 30 (P<0.01), 40 (P<0.001) and 50 (P<0.001) days treatment than the control. Motility of spermatozoa also declined significantly in treated group after 10 (P<0.01), 20 (P<0.01), 30 (P<0.001) 40 (P<0.001) and 50 (P<0.001) days treatment than the control. However, abnormality of spermatozoa increased significantly in treated group of mice during 10 (P<0.01), 20 (P<0.01), 30 (P<0.001) 40 (P<0.001) and 50 (P<0.001) days treatment than the control. Thus significant decrease in sperm counts, motility and increased abnormality of spermatozoa altered the seminal quality which caused infertility among treated group of mice. Effect of the treatment on reproductive organs and fertility was also investigated. The results revealed that Ocimum treatment caused decrease in the weight of reproductive organs viz., testis (P<0.001), epididymis (P<0.01), seminal vesicle (P<0.001), vas deferens (P<0.01) and ventral prostate (P<0.001) significantly when compared to the control group. The recovery group of animal, which also received 50 days treatment, was maintained for 90 days without any treatment to check the reversibility. All the animals after the recovery period showed normal fertility rate. Thus Ocimum sanctum adversely affects fertility in mice and showed anti-fertility effect among them. From this we can conclude that Ocimum sanctum can be used as a potent anti-fertility agent which is reversible. Key-wordsOcimum sanctum, Anti-fertility, Sperm count, Motility, Sperm abnormality -------------------------------------------------IJLSSR----------------------------------------------INTRODUCTION One of the important concerns today’s is the problem of over population. If the population increase is not controlled or checked, it will lead to several problems (Sailani and Moeini, 2008). The solution to this predicament is population control. India opted for family planning to control the increase in population (Sarkar, 1996). Various methods of contraception were used for fertility control. There are a variety of methods available and are in use for female contraception (Bajaj, 1999). In contrast, except for the barrier method and vasectomy, there are no methods available for male contraception. Thus, there is need to develop multiple male contraceptive methods. The risk obtained by the drugs has triggered the need to develop newer molecules from medicinal plants. Access this article online Quick Response Code: Website: www.ijlssr.com

Applications of L-arginine functionalised green synthesised nickel nanoparticles as gene transfer vector and catalyst

ABSTRACTGreen synthesised nickel nanoparticles (NiGs) using Ocimum sanctum leaf extract have been stabilised with L-arginine (Arg–NiGs) and used as gene transfer vector for bacterial transformation and as catalyst for hydrolytic dehydrogenation. Effective binding of L-arginine with NiGs was confirmed by characterisation of Arg–NiGs. L-arginine coating on NiGs prevented the agglomeration of NiGs and reduced the size of the nanoparticles. Synthesised Arg–NiGs was conjugated with green fluorescent protein (GFP) inserted pUC 18 (pDNA–Arg–NiGs) and employed for transforming non-competent Escherichia coli DH5 α. Transformation efficiency of pDNA–Arg–NiGs was found to be higher (3.8 × 106 µg–1 DNA) than the CaCl2-mediated method (2.9 × 105 µg–1 DNA). Fluorescence micrograph of transformants showed enhanced uptake and transformation of pDNA–Arg–NiGs by bacterial cells. Electrophoretic analysis of expressed GFP confirmed that pDNA could retain its functional activity even after binding with Arg–NiGs. This biocompatible, efficient and economical method could be exploited for transforming non-competent bacterial cells. Arg–NiGs catalysed hydrolytic dehydrogenation of ammonia borane (AB) generated 198 mL of hydrogen in 8 min with 128 mg AB and 10 mL of catalyst at 35 °C. The hydrogen generation rate of Arg–NiGs catalysed AB dehydrogenation was determined to be 24.8 mol H2 min–1 with activation energy (Ea) of 34.05 kJ mol–1 and turnover frequency (TOF) of 12.30 mol H2 (mol Ni) –1 min–1. Arg–NiGs retained 89% of its initial catalytic activity even after 10 recycles, indicating its high durability in catalytic reactions. Kinetic studies of AB dehydrogenation by Arg–NiGs show the first-order kinetics with respect to catalyst concentration and zero-order kinetics with respect to AB concentration. This efficient and durable catalyst could be applied in hydrolytic dehydrogenation of AB for effective hydrogen storage.

Ocimum sanctum leaf extract induces drought stress tolerance in rice

ABSTRACTOcimum leaves are highly enriched in antioxidant components. Thus, its leaf extract, if applied in plants, is believed to efficiently scavenge ROS, thereby preventing oxidative damage under drought stress. Thus, the present study was performed in kharif 2013 and rabi 2014 season to evaluate the effect of aqueous leaf extract of Ocimum sanctum against drought stress in 2 rice genotype under glass house conditions. Here we show that various morpho- physiological (chlorophyll fluorescence, leaf rolling score, leaf tip burn, number of senesced leaves and total dry matter) and biochemical parameters (proline, malondialdehyde and superoxide dismutase content) were amended by Ocimum treatment in both the seasons. Application of Ocimum extract increased expression of dehydrin genes, while reducing expression of aquaporin genes in drought stressed rice plant. Thus, application of Ocimum leaf extract under drought stress can be suggested as a promising strategy to mitigate drought stress in economical, accessible and ecofriendly manner.

Preparation of cellulose composites with in situ generated copper nanoparticles using leaf extract and their properties

In the present work, copper nanoparticles (CuNPs) were in situ generated in cellulose matrix using Ocimum sanctum leaf extract as a reducing agent and aq. CuSO4 solution by diffusion process. Some CuNPs were also formed outside the film in the solution which were separated and viewed by Transmission electron microscope and Scanning electron microscope (SEM). The composite films showed good antibacterial activity against Escherichia coli bacteria when the CuNPs were generated using higher concentrated aq. CuSO4 solutions. The cellulose, matrix and the composite films were characterized by Fourier transform infrared spectroscopic, X-ray diffraction, thermogravimetric analysis and SEM techniques. The tensile strength of the composite films was lower than that of the matrix but still higher than the conventional polymers like polyethylene and polypropylene used for packaging applications. These biodegradable composite films can be considered for packaging and medical applications.

Wound healing effect of alcoholic extract of Ocimum sanctum linn. on rats

Wound healing is the process of repair that follows injury tothe skin and other soft tissues. It can result from injurious process ranging from acute disruption of tissue by surgeons knife to wide spread trauma, such as burns. It is well known that traditional herbal medicines existed before the application of the modern scientific methods to health care and even today most of the rural Indian population depend on herbal care practices. Since time immemorial indigenous plant material are being used for healing of wounds. This research work focus to find out healing effect of Ocimum Sanctum (Alcoholic extract) on incisional wound and its effects were compared on the 10th day by wound breaking strength. The wound breaking strength of control group (275gm), standard group (474.4gm) and alcoholic extract 400mg/kg(449.4gm), 800mg/kg(474.3gm). it is concluded that Ocimum Sanctum leaf extract i.e. alcoholic (400 & 800 mg) has significant wound healing effect.

Allelopathic Effect of Extracts of Medicinal Plants on Mungbean in Vivo Conditions

The experiments were conducted at Chaudhary Sarwan Kumar Krishi Vishavidhyalaya,Palampur, Himachal Pradesh, India to see the allelopathic effect of medicinal leaf extracts of Ocimum sanctum L., Calotropis procera(Ait.) Ait.f and Astragalus tribuloides Delile on the plumule length of mungbean (Vigna radiata L. Wilczek) in vivo conditions. The results indicated that different extracts such as alcoholic,aqueous acidic and alkaline extract of Ocimum sanctum L., Calotropis procera(Ait.) Ait.f and Astragalus tribuloides Delile showed different plumule length of mungbean in vivo conditions. All the extracts of Ocimum sanctum L.showed no effect in comparison of control. The alcoholic extract of Calotropis procera(Ait.) Ait.f, produce considerably higher as compared to control followed by aqueous, acidic but alkaline extract showed negative effect on plumule length of mungbean. However, the alcoholic and alkaline extracts of Astragalus tribuloides Delile showed positive effect than aqueous acidic extract on the plumule of mungbean.

Preparation and properties of cellulose/silver nanoparticle composites with in situ-generated silver nanoparticles using Ocimum sanctum leaf extract

ABSTRACTIn the present work, silver nanoparticles were in situ-generated in cellulose matrix using Ocimum sanctum leaf extract as a reducing agent. Regenerated wet cellulose films were first immersed in O. sanctum leaf extract and then it was allowed to diffuse into the films. The leaf extract–diffused wet films were dipped in different concentrated aq.AgNO3 solutions. The leaf extract inside the wet films reduced AgNO3 into nanosilver. The dry composite films were black in color. Some of the nanoparticles were also formed outside the film in the solution. The nanoparticles were viewed by transmission electron microscopy and scanning electronic microscopy techniques. The composite films showed good antibacterial activity. The cellulose, matrix, and the composite films were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis techniques. The tensile properties of the composite films were higher than those of the matrix. These biodegradable films can be used for packaging and medical purposes.

Screening Antimicrobial Activity of Nickel Nanoparticles Synthesized Using Ocimum sanctum Leaf Extract

Antimicrobial efficacy of nickel nanoparticles synthesized using leaf extract of Ocimum sanctum (NiGs) was investigated against pathogenic Gram-negative (E. coli, K. pneumoniae, and S. typhi), Gram-positive (B. subtilis, S. epidermidis) bacteria and fungi (C. albicans, C. tropicalis, A. fumigatus, A. clavatus, and A. niger). 100 µg/mL NiGs showed maximum antimicrobial activity against tested pathogens compared to leaf extract and antibiotics. E. coli (25 mm) and C. albicans (23 mm) exhibited higher zone of inhibition at 100 µg/mL NiGs. MIC, MBC, and MFC values of NiGs against all tested pathogens ranged between 25 and 50 µg/mL. Growth of bacterial and fungal cells (105 cfu/mL) was completely inhibited at 50 µg/mL NiGs. E. coli and C. albicans have showed strong antimicrobial activity with 81% and 50% reactive oxygen species (ROS) production, 30 and 16 µg/mL protein leakage, and 95 and 82 U/L LDH leakages, respectively. Gram-negative bacteria and Candida species showed more sensitivity to NiGs at all concentrations tested (25–100 µg/mL) than Gram-positive bacteria and Aspergillus species, respectively. Microbial growth in the presence of NiGs and ascorbic acid confirmed the involvement of ROS in antimicrobial activity. Hence, NiGs induced ROS generation was attributed to the protein and LDH leakage from microbial membranes.

A green synthesis of Pd nanoparticles supported on modified montmorillonite using aqueous Ocimum sanctum leaf extract: a sustainable catalyst for hydrodechlorination of 4-chlorophenol

A green synthesis of Pd nanoparticles on montmorillonite clay using Ocimum sanctum leaf extract and its application in hydrodechlorination of 4-chlorophenol in water.

Trapping and Manipulation of Copper Nanoparticles in Rayleigh Regime

The copper nanoparticles were synthesized by green technology using leaf extracts of Ocimum sanctum. The synthesized copper nanoparticles were confirmed by the change of colour after the addition of leaf extract into the copper sulfate solution. The synthesized copper was characterized by X-ray Diffraction (XRD), transmission electron microscopy (TEM) and UV-vis absorption spectroscopy. The copper nanoparticles are crystallized with FCC structure. The synthesized copper nanoparticles exhibit spherical morphology with average particle size of 20 nm. The copper nanoparticle exhibits absorption broad band between 550 nm – 575 nm. The optical trapping effect of Gaussian beam acting on a copper nanoparticle in Rayleigh regime was studied. The optical scattering and optical gradient forces were calculated for 20 nm copper particle.