Synthesis and characterization of MCM-48/Hydroxyapatite nano-composite
to use in drug delivery industry
Hoda.Aghaei 1, Amir. Abbas. Nourbakhsh 2, Rouzbeh.Javadkalbasi 3, Saeed.Karbasi 4
Abstract
Hydroxyapatite (HA) is a famous bioceramics materials due to its good biocompatibility, excellent ability
to form chemical bond with living bone issue and suitable osteoconductivity and its synthesis have been
widely paid attention. Mesoporous materials have more tendency for adsorption and release of drug due
to high specific surface area and suitable pores form. This paper report the synthesis of MCM-48/ HA
nanocomposite based on the growth of nanoparticle of phosphate calcium hydroxyapatite along with
organized silica structure (MCM-48). The sample of MCM-48/HA nanocopmposite produced by insitu
crystallization method in basic environment at room temperature. The synthesis of nanocomposite MCM48/HA was initiated with the dissolution of a surfactant in deionised water and ethanol. After this, diPotassium hydrogen phosphate (K2HPO4), calcium chloride (CaCl2) and tetraethylorthosilicate (TEOS)
were added under stirring conditions. The surfactant was removed by calcination at 550 °C for 5 h.
The materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy
(FTIR), N2 adsorption–desorption isotherms and scanning electron microscopy (SEM). The result of
XRD, FTIR and SEM shows that nanoparticle of hydroxyapatite growth along with silica structure and
size of particle is less than 40 nm. Specific surface area of 1897 m2g-1 and 494 m2g-1 were measured for
the MCM-48 and MCM-48-HA nanocomposite. The pore volumes were 0.85 cm3/g for MCM-48 and
0.43 cm3/g for MCM-48-HA . These differences suggest that the crystal growth mesoporous of MCM-41
are filled by HA nanocrystal of hydroxyapatite blocks the available spaces of the mesoporous silica.
These indicate that the original mesoporous of MCM-41 are filled by HA nanocrystals. The results
confirmed the synthesis of a MCM-48-HA nanocomposite can work as drug storage and release hosts due
to their unique surface and textural properties.
Keywords: Mesoporous materials, MCM-48, Hydroxyapatite, Drug delivery
1
Material department, Islamic Azad University, Najafabad Branch, Isfahan, Iran
Ceramic department, Islamic Azad University, Shahreza Branch, Isfahan, Iran
3
Chemistry department, Islamic Azad University, Shahreza Branch, Isfahan, Iran
4
Medical department, Medical Sciences University, Isfahan, Iran
2
1.Introduction
Porous solids are widely used technically during last decade as adsorbents, which were known as
mesoporous materials at the catalysts and catalyst supports owing to their high surface areas [1]. A
mesoporous material is a material containing pores with diameters between 2 and 50 nm and the pore size
and pore volume of these materials make them suitable potential matrices for hosting and for further
release of a large variety of molecules having therapeutic activity [2] . Recently, ordered mesoporous
materials have been interested as drug storage and release hosts due to their unique surface and textural
properties, including stable mesostructure, tunable pore size, and easily modified surface features for
sitespecific delivery[3]. First successful report on the mesoporous materials (M41 S) by Mobil
researchers, with well defined pore sizes of 20- 500 Å [4]. The high surface area (>1000 m2/g) and
precise tuning of the pores are among the desirable properties of these materials [5,6].
M41S mesoporous molecular sieves including unidimensional hexagonal MCM-41, three-dimensional
cubic MCM-48 and unstable lamellar MCM-50 [15]. MCM-41 is the most investigated member of M41
S series [7]. MCM-48 has been the second member of M41S family with three dimensional channel
systems, which can be indexed to an Ia3d space group [8]. As the purely siliceous mesoporous materials
have been shown to be biocompatible, or sometimes even bioactive, there is an increasing interest in this
class of materials for applications in the field of bioceramics, especially as bone substitute materials.
Furthermore,the highly organized porous silica matrix could be used as a potential controlled drug release
system [9]. Hydroxyapatite [HAp, Ca10(PO4)6(OH)2)] has been widely used as a bone substitute due to
its adequate mechanical properties and the similar composition to bone mineral [9,10]. Moreover, HAp
with various morphologies and surface properties have also been investigated as drug carriers for the
delivery of variety of pharmaceutical molecules because of their biocompatible, osteoconductive,
nontoxic, and noninflammatory properties [11]. This paper reports the synthesis and characterization of
MCM-48/HA nano composite by insitue method. Our aim is to make a material with combined
properties of the mesoporous silica (high area superficial) and the HA to be used in drug releasing. The
structure of final material is characterized by X-ray diffraction (XRD), N2 adsorption-desorption, FTIR
spectroscopy, scanning electron microscopy (SEM). Result showed that incorporation of HA phase in the
mesoporous silica led to a significant change in the structural properties of this system.
2. Experimental
2.1. Synthesis of MCM-48 at room-temperature
A cationic surfactant, C16-TAB (hexadecyltrimethylammonium bromide) was dissolved in
distilled water under constant stirring and then, 50 ml technical grade ethanol (Merck
KGaA,Darmstadt, Germany, 0.87 moles) and 12 ml of aqueous ammonia (Merck KGaA,
Darmstadt,Germany, 25 wt.%, 0.20 moles) were added.after The solution was stirred for 30 min
TEOS was Added After stirring for 2 h at room temperature The sample was filtered and dried in
air at ambient temperature .The surfactant was removed by calcination,which was carried out by
increasing temperature to 550 °C during 5 h.
2.2. Synthesis of nanocomposite MCM-48/Hydroxyapatite by in-situ method at roomtemperature
A cationic surfactant, C16-TAB (hexadecyltrimethylammonium bromide) was dissolved in
distilled water under constant stirring and then, 50 ml technical grade ethanol (Merck
KGaA,Darmstadt, Germany, 0.87 moles)were added. To this,K2HPO and 12 ml of aqueous
ammonia (Merck KGaA, Darmstadt,Germany, 25 wt.%, 0.20 moles) were added. pH 12 was
controlled. The solution was stirred for 30 min. Then, the calcium chloride was added and the
agitation was kept for 24 h.The Ca/P molar ratio was 1.63 that similar to the stoichiometric
apatite. After this, TEOS was added. After stirring for 2 h at room temperature the resulting solid
was recovered by filtration, washed with deionised water and dried in air at ambient temperature.
The template was removed by calcination at 550 °C for 5 h.
2.3.Characterization
The crystalline phase of the material was carried out by X-ray diffraction.The XRD patterns were
obtained using a Bruker D8Advance X-ray diffractometer using nickel filtered Cu K radiation (λ =
1.5404) at 40 kV and 20 mA. Fourier transform infrared spectroscopy (FTIR) was used to characterize the
typical functional groups of the silica network, and the presence of hydroxyapatite in MCM-48 with a
Gasco spectrophotometer in the range of 4000–400 cm_1. Surface area (BET) and pore volume were
determinated by adsorption–desorption of nitrogen at liquid nitrogen temperature, using sorptometer
Kelvin 1042. Scanning electron microscope (SEM) studies were performed on Seron Technology ,AIS
2100 detector.
3. Results and discussion
The small angle XRD analysis of the MCM-48 and the MCM-48/HA materials are presented in
Fig. 1. All samples exhibit a strong (211) diffraction peak at 2θ ~2.35° that indicate excellent
structural order for the cubic crystallographic space group Ia3d and good agreement with
reported patterns of pure siliceous MCM-48 materials [12] . By formation of hydroxiapetite
through the structure, the intensity of the peak is decreased. The wide angle X-ray diffraction
pattern for MCM-48/HA nanocomposite sample is also shown in Fig. 2. The XRD pattern
showed that the HA was formed through the matrix of mesoporous MCM-48.
Fig. 1. Small angle X - ray diffraction patterns of: (a) MCM-48 and (b) MCM-48-HA nanocomposite
Fig. 2. Wide angle (XRD) pattern of MCM-48/HA nanocomposite
FTIR data of a pure MCM-48 sample and MCM-48/HA nanocomposite after calcinations of
powder are shown in Figure 3. The main peaks characteristic of vibrational modes of the silica
network are detected around 1082- 1085 cm -1and the PO4 -3 region appears at 568-614 cm-1
and the band at 3430 cm -1 is assigned to OH- stretching mode.
Fig. 3. FTIR spectra of: (a) pure MCM-48 and (b) MCM-48-HA nanocomposite
Nitrogen isotherms of MCM-48 and MCM-48-HA nanocomposites are shown in Fig. 4. Nitrogen
adsorption–desorption isotherms of MCM-48 (Fig. 4a) materials exhibit a reversible type IV
isotherm according to the IUPAC nomenclature that is associated with the presence of
mesoporous. Note that the form of the adsorption isotherms is affected by incorporation of
hydroxyapatite. The surface area were1897 m2/g for pure MCM-48 sample and 494 m2/g for
MCM-48-HA nanocomposite. These differences suggest that the crystal growth of
hydroxyapatite blocks the available spaces of the mesoporous silica that indicate the original
mesoporous of MCM-48 are filled by HA nanocrystals.This phenomenon will be approved in
microstructure.The result of BET are shown Table 1.
Fig. 4. N2 adsorption/desorption isotherms for (a) MCM-48 and (b) MCM-48-HA nanocomposit
Table 1
N2 adsorption results
The SEM images in Fig.5 were obtained from a MCM-48 sample and MCM-48/HA after
hydrothermal synthesis at 550K. MCM-48 host (Fig. 5a) indicate that the sample is composed of
agglomerated uniform spheres. As it is illustrated in this figure, the surface morphology of the particles
in MCM-48/HA composite sample has been altered Fig (b), which is due to the HA growth on the surface
and into pores of MCM-48, that could be filled internal pores of the structure and varied the surface
morphology. Each aggregate contion mesoporous particles but sem has not ability to show them.
Fig. 5. SEM results for (a) pure MCM-48 (b) ,MCM-48-HA nanocomposite
4. Conclusions
In this study, an easy synthesis route for making a MCM-48/HA composite material is presented. The
incorporation of HA phase in the mesoporous silica led to a significant change in the structural properties
of this system, indicating that the crystal growth of hydroxyapatite blocks the available spaces of the
mesoporous silica in agreement with the SEM/EDS results and that the original mesoporous of MCM-48
are filled by HA crystals, as shown by N2 adsorption results. However, HA incorporation leads to a
decrease in textural characteristics like surface area, and pore volume. The results confirmed the synthesis
of a MCM-48-HA nanocomposite can work as drug storage and release hosts due to their unique surface
and textural properties.
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