Green synthesis of silver nanoparticles and modification with paper pulp for antimicrobial applications Luis A. Deschamps, Gesira De Avila, and Adriana P. Herrera* Chemical Engineering Program. Faculty of Engineering. University of Cartagena, Colombia. *Contact information: aherrerab2@unicartagena.edu.co
Adsorption of silver nanoparticles in paper pulp
Components presents in the coriander leaf extract, with their respective functional groups as according with the FTIR.
Introduction
Components
Metallic nanoparticles have been recently used in different biotechnology and biomedical applications, such as additives in textile industry, food packages, proteins immobilization, drugs for cancer treatment, and development of optoelectronic materials, showing a significant increase in the synthesis and modification of these nanomaterials.
Linoleic acid, oleic acid, and palmitic acid
Functional groups CH3-CH2 -CH=CH>C=O COOH CH-CH2 -CH2OH
Ascorbic acid
OHC=COH -O-
Wavelength
a)
b)
2850-2960 3020-3100 1640-1680 3400-3650, 1050-1150 2850-2960 3400-3650, 1050-1150 1670-1780 2500-3100 2850-2960
Silver nanoparticles were adsorbed in paper pulp (cellulose) to evaluate their antimicrobial properties by the disc clinical test. Nanoparticles were adosrbed in concentrations of a) 1 mgAgNPs/mg-paper pulp and b) 5 mg-AgNPs/mg-paper pulp. Afterwards, the discs were dried at 80 °C and then sterilized previous antimicrobial test.
Antimicrobial Evaluation: Inhibition of E. coli growth Implementation of AgNPs as antimicrobial agents.
Olivia Ong and Juan Hinestroza. Cornell University. Antimicrobial coat
Objetives Synthesize eco-friendly silver nanoparticles by using a natural leaf extract from coriander (Coriandrum sativum) as the reduction agent. Characterize the physico/chemical properties of the synthesized nanoparticles Modify the synthesized nanoparticles incorporation in a cellulose matrix
4500
4000
3500
3000
2500
Wavelength
2000 (cm-1)
1500
1000
500
FTIR spectroscopy of the as prepared coriander leaf extract
The antimicrobial evaluation of the synthesized silver nanoparticles modified with paper pulp was achieved following the procedure described by Bauer- Kirby (1969), which it is the standard procedure adopted for the National Committee for the Normalization of Clinic Labs. From these measurements we observed the inhibition of E-Coli growth after 24 and 48 h of contact time for concentrations of a) 1 mg-AgNPs/mg-paper pulp and b) 5 mg-AgNPs/mg-paper pulp, and c) paper pulp discs without nanoparticles, which were used as control
Synthesis and characterization of the silver nanoparticles: a)
by
Evaluate the antimicrobial effect of the silver nanoparticles in contact with the E. coli bacteria
Methodology Extraction and characterization of the natural solvent:
(I) 24 h We added 2.5 ml of the coriander leaf extract solution to 50 ml of an aqueous AgNO3 solution (1 or 100 mM). Then, the formation of the nanoparticles was performed at room temperature for 10 min. Afterwards, temperature was increased up to 80 °C and the reaction was carried out at this temperature during 20 min at 200 rpm. Then, the nanoparticles were precipitated by centrifugation and suspended in distilled water at pH 10
a)
(II) 48 h
b)
b)
c)
c)
Absorbancia a.u
0,7
To prepare the natural solvent, we weighted 100 g of the coriander leaves, which were previously washed with distilled water and suspended in 250 ml of distilled water This solution was heated up to 200 °C during 20 min at 500 rpm. Then, it was concentrated by adding 100 g of the coriander leaves and repeating the heating process. Afterwards, the solution was concentrated up to 50 ml by evaporation of water.
Absorbancia
2,5 2 1,5 1 0,5 0 300
350
400
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500
Uv-vis spectroscopy of the coriander extract. From this measurement, we do not observe any peak at the range from 400 to 450 nm-1
0,6 1 mM
0,5
100 mM
0,4 0,3 0,2
300
350
400
450
500
(nm-1) UV-Vis spectroscopy of silver nanoparticles synthesized from an aqueous AgNO3 solution prepared at a) 1mM and b) 100 mM. We observed characteristics peaks at 410 and 425 nm-1, which indicates the formation of these nanoparticles. The hydrodynamic size of the synthesized nanoparticles were determined by Dynamic Light Scattering (DLS), obtaining a size of a) 75 ± 30 nm and b) 80 ± 28 nm.
Scanning electron microscopy (SEM) of the synthesized nanoparticles taken at magnification of 10 m.
(nm-1) 10 m
a)
b)
c)
Microscope images of paper pulp samples modified with silver nanoparticles after 48 h of contact time with E-Coli bacteria. Inhibition of E-Coli growth was observed for samples prepared at a) 1mg AgNPs/mg paper pulp, b) 5mg AgNPs/mg paper pulp, and c) paper pulp disc without addition of nanoparticles.
Conclusions The eco-friendly synthesis of silver nanoparticles was achieved by reducing an aqueous AgNO3 solution by using a natural leaf extract from coriander. The hydrodynamic size and wavelength peak of the synthesized nanoparticles were independent of the concentration of the silver-salt precursor. The synthesized nanoparticles were able to be dispersed in paper pulp showing good antimicrobial properties after contact with E-Coli during 24 and 48 h, which indicate us the suitability of these nanoparticles for the production of bio-active food packs.
Acknowledgements University of Cartagena, Colombia University of Puerto Rico. NANOmaterials Processing Lab. Science and Materials Engineering Department. Dr. Oscar Perales and MSc. Boris Renteria