Materials Sciences and Applicatio ns, 2011, 2, 578-581
doi:10.4236/msa.2011.26077 Published Online June 2011 (http://www.SciRP.org/journal/msa)
Synthesis of Silver Nanoparticles Using Albumin as
a Reducing Agent
Elpidio Morales-Sánchez1,2,3, Jesús Guajardo-Pacheco1,2,3, María Noriega-Treviño1,2,4,
Cristina Quintero-González2,4, Martha Compeán-Jasso2, Francisco López-Salinas1,2,3,
Jesús Gonz ález-Hernández 3, Facundo Ruiz2
1Departamento Físico Matemáticas de la Universidad Autónoma de San Luis Potosí, Álvaro Obregón, Col. Centro, San Luis Potosí,
S.L.P., México; 2Facultad de Ciencias de la Universidad Autónoma de San Luis Potosí, Álvaro Obregón, Col. Centro, San Luis
Potosí, S.L.P., México; 3Centro de Investigación en Materiales Avanzados, S.C. (CIMAV), Miguel de Cervantes 120 Complejo
Industrial Chihuahua, México; 4Doctorado Institucional de Ingeniería y Ciencia de Materiales de la Universidad Autónoma de San
Luis Potosí, Alvaro Obregon, Col. Centro, San Luis Potosí, S.L.P., México.
Received February 15th 2011; revised March 1st, 2011; accepted April 1st, 2011.
ABSTRACT
The preparation of stable, uniformed silver nanoparticles by the reduction of silver ions using albumin is reported in
the present paper. It is a simple process for obtaining silver nanoparticles. The samples have been characterized by
X-ray diffraction (XRD) and transmission electron microscopy (TEM), which reveal the nature of the nanoparticles.
These studies conclude that the particles are mostly spherical in shape and have an average size of 26 nm. The UV-vis
spectra show that an absorption band, occurred because of the Surface Plasmon Resonance, existing at 443 nm; the
Thermogravimetric Analysis (TGA) shows that only 2% of the weight is organic matter. The average particle size was
measured with a Nanosizer DLS.
Keywords: Reducing Agent, Albumin, Silver Nanoparticles
1. Introduction
With the aim of developing new ways to produce metal-
lic nanoparticles by using materials that are environment-
tally friendly, we propose this novel method of producing
metallic nanoparticles like Ag, Pt by using albumin as a
reducing agent. Improvement in the quality of both the
environment and working conditions offers one of the
primary reasons for industries to turn to green products
as alternatives to chemicals. In this paper, we have re-
ported the synthesis of silver nanoparticles by reducing
silver ions, employing albumin as the reducing agent.
The albumin protein was used as a covalent attach-
ment of metal chelates to protein, with a chelate of in-
dium [1]. The stabilization by Natural biosurfactant was
used in the synthesis of silver nanoparticles [2]. The soil
contamination with toxic metal has become a major en-
vironmental concern in many parts of the world due to
rapid industrialization. The use of chelating agents is the
remediation of metal contaminated soils. [3].
The attachment of metal-chelating groups as albumin
and some proteins have been found in medical applica-
tions [4,8].
In recent years nanoparticles of silver have been found
to exhibit interesting antibacterial activities [9].
A variety of preparation routes have been reported for
the preparation of silver nanoparticles. Silver salt reduce-
tion was the most used [10,15].
In the present paper, we report a simple and “green”
chemical synthesis of silver nanoparticles from albumin.
The silver NPs were characterized by UV-vis absorption
spectrum measurements and transmission electron mi-
croscopy (TEM),
2. Materials and Methods
2.1. Reagents
Albumin, AgNO3, purchased from Sigma-Aldrich, and
ammonium hydroxide (29.9%, Fermont) were used
without any further purification. Mili-Q water (18.2 Ω)
was used throughout the experiment.
2.2. Characterization
The optical absorption spectra were obtained with an

Synthesis of Silver Nanoparticles Using Albumin as a Reducing Agent579
Oceanoptics S2000-UV-Vis system; transmission elec-
tron microscopy TEM images at 100 kV was carried out
using a JEOL-1230. Thermogravimetric Analysis (TGA)
was made and the average particle size was measured
with a Nanosizer DLS.
2.3. Synthesis of Silver Nanoparticles
Silver nanoparticles were prepared in an aqueous solution
by reducing Ag+ ions with albumin solution. The detailed
synthetic procedure of silver nanoparticles is as follows:
A albumin solution was prepared dissolving 0.1 grams of
albumin in 30 ml of deionizer water. Another AgNO3
solution was prepared dissolving 0.05 grams of AgNO3 in
10 ml of deionizer water. The particles were prepared by
mixing the silver ion solution with the albumin solution in
a magnetic stir and after 5 minutes, 29.9% ammonium
hydroxide was added in drop form, producing an adjust-
ment of pH = 11. It was stirred magnetically for 15 min-
utes, it was necessary to let the solution settle for 24 hours,
because the reaction speed is slow. After that time, the
nanoparticles were formed. The silver nanoparticles were
recovered by filtration and afterwards washed a minimum
of 3 times with ethylic alcohol.
3. Results and Discussion
In order to find the pH at which the albumin has reducing
property, we varied the pH slowly, adding an ammonium
hydroxide dilute solution and measured the reducing po-
tential continuously. Figure 1 shows the results and we
can see that albumin acts as a reducer with a pH greater
than 10.4. As a result we raised the pH of the final mix of
the silver solution and the albumin solution to 11.
Colloidal dispersion of metal exhibits absorption bands
or broad regions of absorption in the ultra violet-visible
range. These are due to the excitation of plasmon reso-
nance or interband transition and are a characteristic
property of the metallic nature of the particle. For exam-
ple, nanosized Ag particles typically exhibit a surface
plasmon peak at around 420 nm. To monitor the stability
of the final prepared silver nanoparticles, we measured
the absorption spectra of the solution when it was pre-
pared we measured it again, six month later. As shown in
Figure 2, the silver nanoparticles obtained initially show
an absorption peak about 443 nm (solid line) and the
plasmon absorption band of the same sample measured
six months after its preparation (dash line) shows only a
small change, at 458 nm. The decrease in the absorption
of the sample after six months indicates a small increase
of silver nanoparticles.
A representative TEM image is shown in Figure 3.
The TEM indicates that the morphology of the silver
nanoparticles obtained is spherical and relatively uniform;
the size distribution observed is narrow. Most of the par-
ticles range in size from 5 to 20 nm. We see that the av-
erage diameter of the particles is about 13 nm. We can see
that the silver nanoparticles are well separated with no
sign of aggregation. The mean superficial area is 44 m2/g.
Figure 4 shows the size distribution of the silver parti-
cles obtained with LSD nanosizer equipment. We can see
that the diameter of the silver particles is 26.82 nm with a
band width of 6.43 nm, indicating that the size distribu-
tion of the silver nanoparticles is narrow. This result is
similar to the TEM image we obtained.
In order to find the number of silver nanoparticles and the
amount of organic material, we obtained a TGA of a typical
sample we had prepared. The TGA is shown in Figure 5.
Three phases of endothermic change are observed.
They are marked with the numbers (1), (2), and (3). Point
(1) refers to the water evaporation; the sample has 35%
Figure 1. Variation between pH and reducing potential of
albumin solution.
Figure 2. Comparison of UV-vis absorption spectra between
samples of Ag as first prepared (solid line) and six month
later (dash line).

Synthesis of Silver Nanoparticles Using Albumin as a Reducing Agent 580
Figure 3. TEM image of a prepared sample silver nanopar-
ticles.
Figure 4. Size distribution of a sample of silver prepared.
Figure 5. TGA of a sample of silver nanoparticles.
weight of water. Point (2) presents a small shoulder cor-
responding to organic material decomposition; the quan-
tity of organic material is merely 2% weight, a very small
percentage. It is possible to reduce the organic material
further by washing the sample more times. Point (3)
represents the fusion of silver particles; the melting point
of silver bulk is 961.9˚C, which corresponds to Point (3).
4. Conclusions
In conclusion, the bio-reduction of aqueous Ag+ ions by
the natural “green” albumin has been demonstrated. The
silver ion reduction through albumin for the formation of
silver nanoparticles of fairly well-defined dimensions.
This green chemistry approach toward the synthesis of
silver nanoparticles has many advantages such as the
ease with which the process can be scaled up, economic
viability, etc. Albumin can be used by nanotechnology
processing industries. With this method we can obtain a
large amount of small silver nanoparticles in a narrow
size range. The agglomeration of particles after six
months varies only by a small percentage. The morphol-
ogy of the nanoparticles is spherical. We can say that the
stability of the nanoparticles holds well for several
months because a high percentage of the particles retain a
nanometric size.
REFERENCES
[1] C. F. Meares, D. A. Goodwin, C. S.-H. Leung, A. Y.
Girgis, D. J. Silvesteri, A. D. Nunnf and P. J. Laender,
“Covalent Attachment of Metal Chelates to Proteins: The
Stability in Vivo and in Vitro of the Conjugate of Albu-
min with a Chelate of 111Indium,” Proceedings of the Na-
tional Academy of Sciences in USA, Vol. 73, No. 11, 1976,
pp. 3803-3806.
[2] Y. W. Xie, R. Q. Ye and H. L. Liu, “Synthesis of Silver
Nanoparticles in Reverse Micelles Stabilized by Natural
Biosurfactant,” Colloids and Surfaces A: Physicochemi-
cal and Engineering Aspects, Vol. 279, 2006, No. 1-3, pp.
175-178. doi:10.1016/j.colsurfa.2005.12.056
[3] G. A. Brown and H. A. Elliott, “Influence of Electrolytes
on EDTA Extraction of PB from Polluted Soil,” Water,
Air and Soil Pollution, Vol. 62, No. 1-2, 1992, pp 157-
165. doi:10.1007/BF00478458
[4] S. Tandy, K. Bossart, R. Mueller, J. Ritschel, L. Hauser,
R. Schulin and B. Nowack, “Extraction of Heavy Metals
from Soils Using Biodegradable Chelating Agents,” En-
vironmental Science and Technology, Vol. 38, No. 3,
2004, pp. 937-944. doi:10.1021/es0348750
[5] C. S. H. Leung, C. F. Meares and D. A. Goodwin, “The
Attachment of Metal-Chelating Groups to Proteins: Tag-
ging of Albumin by Diazonium Coupling and Use of the
Products as Radiopharmaceuticals,” The International
Journal of Applied Radiation and Isotopes, Vol. 29, No.
11, 1978, pp. 687-692.
doi:10.1016/0020-708X(78)90107-2
[6] C. S.-H. Leung and C. F. Meares, “Attachment of Fluo-
rescent Metal Chelates to Macromolecules Using ‘Bi-
functional’ Chelating Agents,” Biochemical and Bio-
physical Research Communications, Vol. 75, No. 1, 1977,
pp. 149-155. doi:10.1016/0006-291X(77)91302-X
[7] C. J. Anderson, P. A. Rocque, C. J. Weinheimer and M. J.

Synthesis of Silver Nanoparticles Using Albumin as a Reducing Agent 581
Welch, “Evaluation of Copper-Labeled Bifunctional
Chelate-Albumin Conjugates for Blood Pool Imaging,”
Nuclear Medicine and Biology, Vol. 20, No. 4, 1993, pp.
461-467. doi:10.1016/0969-8051(93)90077-8
[8] E. M. Egorova and A. A. Revina, “Synthesis of Metallic
Nanoparticles in Reverse Micelles in the Presence of
Quercetin,” Colloids and Surfaces A: Physicochemical
and Engineering Aspects, Vol. 168, No. 1, 2000, pp.
87-96. doi:10.1016/S0927-7757(99)00513-0
[9] M. A. H. Muhammed, P. K. Verma, S. K. Pal, A.
Retnakumari, M. Koyakutty, S. Nair and T. Pradeep,
“Luminescent Quantum Clusters of Gold in Bulk by
Albumin-Induced Core Etching of Nanoparticles: Metal
Ion Sensing, Metal-Enhanced Luminescence, and Bio-
labeling,” Chemistry—A European Journal, Vol. 16, No.
33, 2010, pp. 10103-10112.
doi:10.1002/chem.201000841
[10] M. G. Guzmán, J. Dille and S. Godet, “Synthesis of
Silver Nanoparticles by chemical Reduction Method and
their antibacterial activity,” World Academy of Science,
Engineering and Technology, Vol. 43, 2008, pp. 357-364.
[11] S. D. Salomon, M. Bahadory, A. V. Jeyarajasingam, S. A.
Rutkowsky, C. Boritz and L. Mulfinger, “Synthesis and
Study of Silver Nanoparticles,” Journal of Chemical
Education, Vol. 84, No. 2, 2007, pp. 322-325.
doi:10.1021/ed084p322
[12] T. Maiyalagan, “Synthesis, Characterization and Electro-
catalytic Activity of Silver Nanorods towards the Reduc-
tion of Benzyl Chloride,” Applied Catalysis A: General,
Vol. 340, No. 2, 2008, pp. 191-195.
doi:10.1016/j.apcata.2008.02.016
[13] G. A. Martínez-Castañón, N. Niño-Martínez, F. Martínez-
Gutierrez, J. R. Martínez-Mendoza and F. Ruiz, “Cha-
racterization of Silver Nanoparticles Synthesized on
Titanium Dioxide Fine Particles,” Nanotechnology, Vol.
19, No. 6, 2008, pp. 1343-1348.
[14] S. Panigrahi, S. Kundu, S. K. Ghosh, S. Nath and T. Pal,
“General Method of Synthesis for Metal Nanoparticles,”
Journal of Nanoparticle Research, Vol. 6, 2004, pp. 411-
414.
[15] T. Tuval and A. Gedanken, “A Microwave-Assisted
Polyol Method for the Deposition of Silver Nanoparticles
on Silica Spheres,” Nanotechnology, Vol. 18, 2007, p. 7.