Facile synthesis of mesoporous alumina using hexadecyltrimethylammonium bromide (HTAB) as template: simplified sol‐gel approach

Abstract

Herein the authors present the synthesis of surface functionalised mesoporous alumina (MeAl) for textural characterisation by a simplified sol–gel method obtained by using hexadecyltrimethylammonium bromide as a template. Etoricoxib (ETOX) was used as a model drug for the study. Alumina supported mesoporous material containing drug was characterised using instrumental technique namely Brunauer–Emmett–Teller surface area, Fourier transform‐infrared, differential scanning calorimetry, transmission electron microscopy, X‐ray diffraction, and field emission scanning electron microscopy. Diffusion study using a dialysis bag method used to check the release pattern of ETOX‐loaded‐MeAl. Results of characterisation study revealed the successful surface functionalisation of the drug on nanocomposite. The IC₅₀ value obtained from cell viability study demonstrated the non‐toxic behaviour of synthesised drug‐loaded mesoporous alumina up to the tested concentration range. The present work has demonstrated that synthesised MeAl showed excellent stability with an expanded surface area suitable for carrier material for drug delivery system.

1 Introduction

Since the last decade, drug‐loaded nanostructured mesoporous alumina (MeAl) nanoparticles gained appreciable popularity and attention in nanotechnology [1, 2]. Owing to nano pore size, broad surface area, ordered porosity, easy functionalisation ability with organic compounds, excellent host–guest chemistry, favourable textural properties, and extraordinary catalytic capacity, the surface functionalisation stabilises the required amount of drug entity in the pores of porous alumina [3, 4, 5]. As a result, these unique properties emerged MeAl as a potential candidate in various aspects [6, 7]. In terms of novel drug delivery aspects, biocompatible MeAl nanoparticles have benefited to biomedical and pharmaceutical drug delivery system [8, 9]. International Union of Pure and Applied Chemistry (IUPAC) system has classified inorganic solid porous material as microporous, mesoporous, and macroporous [10, 11]. The conventional inorganic ceramic nanofibre alumina is a metastable polymorph with irregular pore geometry [12, 13, 14]. Thus, the untreated alumina possesses a problem of rapid deactivation in the catalytic process and thus unsuitable for drug loading and release of therapeutic agents in order to deliver in the physiological system [15, 16, 17]. To date, there is no work explored on Etoricoxib‐loaded MeAl (E‐MeAl). Therefore, an envisaged attempt was conducted to synthesise stable mesoporous alumina, an ultimate and versatile vehicle possesses inbuilt properties such as narrow pore size with long range ordering, uniform pore density, robust, mechanical and chemical stability and highly suitable as a vehicle for delivery of the selected model drug [18, 19, 20, 21, 22, 23]. Here, a chemical sol–gel method approach utilised to synthesise alumina‐based mesoporous material (pore size 2–50 nm) by special treatment and hydrolysis with organometallic compounds and inexpensive inorganic salt, as starting material [24, 25, 26, 27, 28, 29]. The reagents used in synthesis react with host molecules to command the porosity and particle size of nanofibre [30, 31]. The alumina‐based stable mesoporous material can be categorised either as cylindrical [two‐dimensional (2D)] or cage type (3D) structure depending on their structure dimension and geometry of pores. The 2D mesoporous material carries uniform pore size, provides applicability in catalysis reaction and as a drug delivery vehicle. The 3D geometry of mesocaged alumina could be applicable to control the mass transfer of therapeutic agents [32, 33].

In the present work, E‐MeAl was successfully prepared. Hexadecyltrimethylammonium bromide (HTAB) was used as a template for synthesis of MeAl and functionalised with a therapeutic agent that supported to determine the selectivity of surface groups for coupling. The drug–surface interaction, surface functionalisation, composite surface morphology, and thermal behaviour were corroborated, respectively, using techniques such as Fourier transform infrared (FT‐IR) spectroscopy (FT‐IR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron dispersive X‐ray (EDX) and differential scanning calorimetry (DSC) represents the successful loading of model drug Etoricoxib (ETOX). In addition, the drug release behaviour and cytotoxicity study were conducted. The drug release pattern and other analytical investigations of selected model drug represented the improved solubility and drug release. Cytotoxicity study investigated the cytotoxic behaviour of E‐MeAl nanoparticles at various concentrations. The outcome of the present work demonstrates the significant potential of developed E‐MeAl nanocomposite as a novel delivery technique for poorly water soluble drugs.

2 Materials and methods

2.1 Materials

ETOX was received as a benevolent gift from Intas Pharma Pvt. Ltd, Ahmedabad, 3‐aminopropyltriethoxysilane (APTES), 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide (EDC) was purchased from Sigma Aldrich, Germany. All the reagents and solvents used were of analytical grade.

3 Methods

3.1 Synthesis of MeAl

The MeAl was synthesised using HTAB as a template. The solution of 500 mg of HTAB into 23 ml ethanol was refluxed on magnetic stirring and allowed to reach the temperature of up to 70°C. Furthermore, a homogeneous solution of aluminium chloride (2.6 g) and urea (0.7 g) in 20 ml water was added continuously in a drop wise manner. After 30 min of reaction, 6 ml of 28% ammonia solution was added. The reaction was continued further for 2 h at 70°C. After completing the aging time of 3–6 h, the solvent was removed by heating at 100°C for 5–7 h. The resulting precipitate was heated at about 500°C (calcination). The obtained mesoporous alumina particles were washed in triplicate with water and ethanol to remove traces of surfactant chains.

3.2 Functionalisation of MeAl

About 200 mg MeAl particles were heated at 100°C for 3 h and added into toluene containing 2 ml of APTES and further heated for 16 h using a reflux condenser. Then MeAl particles were washed 2–3 times with toluene and thrice with acetone to remove the unreacted coupling agent. Functionalised mesoporous particles were then heated at 40°C for 12 h in the air for removal of solvent.

3.3 Drug loading

To evaluate the performance of MeAl for hosted pharmaceutical, ETOX was used as the model drug. Functionalised MeAl particles were heated at 100°C for 3 h to remove the moisture. MeAl particles (300 mg) in methanol containing ETOX (300 mg, i.e. 1 mg/ml) were stirred for 12 h. A specified quantity of coupling agent was added and stirred continuously for 12 h. ETOX‐loaded samples were recovered by filtration using a vacuum and allowed for drying up to 24 h at 30°C. The effective uptake of ETOX functionalised MeAl immersed in a solution of the drug was determined using ultraviolet (UV)‐spectrophotometric technique.

4 Characterisation of synthesised MeAl

4.1 Fourier transform infrared spectroscopy (FT‐IR)

The FT‐IR spectra of ETOX, MeAl, and drug‐loaded MeAl were recorded on an FT‐IR‐ 4100 (Jasco) spectrophotometer over the range 500–4000 cm⁻¹ [34].

4.2 Powdered XRD study

All mesoporous samples were subjected to XRD study to determine the crystalline nature on a Bruker XRD model, Bruker, Japan. The phase analysis of MeAl samples was conducted using XRD, with CuKα radiation at 40 kV and 40 mA.

4.3 Field emission SEM (FESEM)

FESEM analysis was performed to study the surface morphology of MeAl and drug‐loaded MeAl. The samples were coated with platinum in a sputter coater. Then these samples were analysed under FEI Nova NanoSEM 450, USA instrument at 1.8 nm at 3 kV and 30 Pa.

4.4 Transmission electron microscopy (TEM)

TEM analysis was performed to study surface morphology and porous nature of MeAl and drug‐loaded MeAl. TEM was performed on Technai G² 20U‐Twin (FEI, Netherlands). The dispersion of the powdered sample was prepared in methanol and diluted with 5 ml methanol and then sonicated. A drop was placed on a copper grid. These grids were placed in a sample holder and images were recorded, respectively. These images were interpreted based on morphological characteristics.

4.5 EDX analysis

EDX analysis was performed to determine the elements present in the sample. Qualitative and quantitative analysis was performed by using Bruker XFLASH 6130.

4.6 Thermal analysis

DSC study was conducted to determine the thermal changes. Thermal analysis of ETOX, MeAl, and E‐MeAl was performed on a Perkin Elmer 4000, which was calibrated for temperature and enthalpy using pure indium. Drug (3–5 mg) was crimped in non‐hermetic aluminium pans with lids and scanned from 50°C to 300°C at a heating rate of 10°C/min under a continuously purged dry nitrogen atmosphere at a flow rate 20 ml/min. The instrument was equipped with a cooling system and atmospheric controller [35].

4.7 Brunauer–Emmett–Teller (BET) analysis and nitrogen sorption isotherm

Nitrogen adsorption and desorption isotherm were measured to confirm the porosity of particle on Monosorb, Quantachrome Instruments, USA at liquid nitrogen temperature (77.4 K). To calculate the surface area, the BET method was used. Before the determination of the sample, clean up by degassing at 200°C for 6 h to remove any traces of water and impurities in the solid surface was carried out. To measure the particle size of the sample equivalent amount of sample was weighed and calculated according to the following formula:

$$D_{\mathrm{DBT}}=6000/\mathrm{P}{\mathrm{S}}_{\mathrm{BET}}$$

where D _BET is the average particle size by nm, S _BET is the specific surface area expressed in m² /g and ρ is the theoretical density expressed in g/cm³.

4.8 Particle size and polydispersity index (PDI)

The average surface of the synthesised mesoporous particle, pore diameter, and size distribution was determined by Nanophox (Sympatec, Germany). Sample temperature was maintained at 25°C and three runs of 60 s at a scattering angle of 90° [36].

4.9 Zeta potential

The electrical charges present on the surface helps to determine the flocculation rate present on the mesoporous surface was measured using a zeta sizer (Ver 6.20 Malvern Instrument, Germany).

4.10 Determination of drug content in MeAl

After the surface functionalisation of MeAl loaded with ETOX it is important to determine loading capacity. A known concentration of the sample was determined by ultraviolet (UV)–visible (Vis) spectrophotometer at 284 nm.

4.11 In vitro dissolution study

The dialysis bag method was utilised to check the release profile of synthesised mesoporous material. The ETOX released from E‐MeAl was investigated by diffusion bag technique. The release profile was studied in phosphate buffer saline (PBS, pH 7.4 and pH 1.2) bag sealed hermetically and placed in 100 ml of release medium at 100 rpm stirring speed. At a fixed time interval, the sample was removed and replaced with the same volume and then quantified using the UV–Vis absorption spectrophotometer.

4.12 Cell viability study

In‐vitro anticancer activity of ETOX‐loaded MeAl was evaluated against passage 89 Chinese hamster ovary (P89 CHO) cell lines. 1% 2 mM antibiotic was added into the cell cultured in Dulbecco modified Eagle's medium containing foetal bovine serum 10% (v/v) at 37°C with 5% CO₂. The cells were taken in the concentration of 200 µl and added to each 96‐well plate. After allowing the sufficient contact time for surface attachment to cells, all plates were placed in an incubator for 24 h at 37°C. Further growth medium was changed and medium concentration 10 µl of fresh medium containing a varying concentration of sample was added to the cells. Methyl thiazole tetrazolium (MTT) containing medium was added to each plate, after the incubation of 24 h, the medium was removed and washed with PBS. All the plates containing 150 µl of medium and 50 µl of MTT was placed in an incubator for 5 to 6 h. After that MTT was removed and the final measurement was taken at 570 and 650 nm.

5 Results and discussion

5.1 Fourier transform infrared spectroscopy (FT‐IR)

The FT‐IR study of synthesised MeAl and drug‐loaded MeAl (using HTAB as a template) was ascertained in scanning range between 4000 and 500 cm⁻¹ as represented in Figs. 1 a and b, respectively. The characteristics broad peak observed between 3600 and 3000 cm⁻¹ signifies the presence of OH stretch due to the presence of the surfactant chain (HTAB). The appearance of significant C–H stretch between 3000and 2800 cm⁻¹ indicates the alkyl chain of template molecule HTAB. The appearance of the peak at 1199 cm⁻¹ is due to the deformation bands generated by C–O stretch vibrations of MeAl. The principle sulphonyl group of ETOX responsible for bonding with host appears in the spectrum between 1400 and 1100 cm⁻¹ represents guest conjugation with MeAl. APTES (coupling agent) functionalised alumina leads to generate new band significantly observed near 2800 and 2900 cm⁻¹ due to the symmetric and asymmetric stretch of the CH₂ group (amino alkyl chains of APTES). The Al₂ O₃ –NH group present on the MeAl surface signifies its presence due to the appearance of peaks at 1442 and 396 cm⁻¹ represents N–H bend and N–C stretch, respectively.

Fig. 1.

FTIR spectrum of synthesised

(a) MeAl, (b) E‐MeAl

5.2 XRD study

To understand the nature of the formed MeAl, XRD study was carried out. The diffraction study of MeAl shows the formation of γ‐Al₂ O₃. The X‐ray pattern of MeAl demonstrated (Fig. 2 a) the crystalline nature and associated peaks that typically attributed to γ‐Al₂ O₃ were observed. A small peak at 23.7°, a highly sharp intense peak at 37.6°, small peaks at 40.2°, 47.7°, 54.1°, and 59.3° indicate the crystallographic arrangement of γ‐Al₂ O₃. The diffraction peak of E‐MeAl (Fig. 2 b) represents complete immersion of drug into the pores of mesoporous material. The diffraction angle observed around 5–10 and 20–30 indicates the formation of γ‐Al₂ O₃. Furthermore, no intense peak was observed in E‐MeAl indicates partial loss of crystalline character. The extent of crystallisation and interplanar space changes after surface functionalisation indicating dispersion of ETOX indirectly proves successful functionalisation. However, the XRD pattern clearly indicates a peak with a broad nature at the reduced intensity and shifted to lower 2θ value.

Fig. 2.

Powder X‐ray diffraction pattern of synthesised

(a) MeAl, (b) E‐MeAl

5.3 Field emission SEM (FESEM)

The FESEM study represents an aggregation of a particle with the granular structure of MeAl with a random pore size as shown in Fig. 3 a whereas the spongy structure was observed in Fig. 3 b. From the high magnification, FESEM mesostructure could be observed clearly on the framework with large pores, suggest the hierarchical porous nature of materials. The FESEM image of pure ETOX indicates the rod‐like (Fig. 3 c) structure, which was similar to the E‐MeAl image, confirms the loading of ETOX in MeAl. FESEM image shows subparticles of MeAl with proportionate and ordered pore size, which were aggregated into wheat‐like mesostructures. The FESEM image of the drug‐loaded MeAl sample (Fig. 3 d) revealed the covalent bonding of ETOX to the MeAl particle. The surface topography of E‐MeAl considered as important steps in the synthesis of mesoporous alumina, which confirms the formed E‐MeAl conjugate.

Fig. 3.

FESEM images of

(a) , (b) MeAl, (c) pure ETOX, (d) E‐MeAl

5.4 Transmission electron microscopy (TEM)

TEM reveals a continuous mesoporous network containing MeAl nanoparticles or particles ensemble statistically embedded in porous solid. The aforementioned structure intently resembles one of the Mesoporous nanocomposite material (MNCM)‐templated silica described in earlier literature [37]. The morphological features of surface‐calcined MeAl are shown in Fig. 4 a. The MeAl sample showed a roughly spherical shape of 50 nm in diameter connected by a mesoporous structure. It also consisted of some aggregation appearance and exhibited as hexagonally arranged cylindrical pores. After loading of the drug to the mesoporous matrix (Figs. 4 b and c) consist of non‐aggregated monodispersed spherical particle 50 nm in diameter. In loaded mesoporous matrix possessed a dentritic structure with fibres coming out from the centre and uniformly distributed through all directions. As discussed in [37], nanoparticles formed in MeAl do not aggregate in the sol–gel process supersedes by calcination. Inquisition of TEM micrograph of the sample allows one to distinguish a large population of particles with diameters of 4–6 nm along with larger particle ensembles reaching 50 nm. The latter, in turn, comprise petite discrete particles.

Fig. 4.

TEM image of synthesised

(a) MeAl, (b) , (c) E‐MeAl

5.5 EDX analysis

Synthesised MeAl EDX analysis was conducted for substantiating the presence of alumina. The spectra recorded the presence of Al₂ O₃ with a non‐descript amount of impurities after calcination. EDX analysis also displays a homogeneous circulation of alumina. Elemental analysis of MeAl shows (Fig. 5 a) the presence of strong O and Al peaks at 51.53% of O and 48.47% of Al in MeAl sample indicating the formed mesoporous material with HTAB and EDC. Furthermore, it was found that there was presence of other peaks such as C, Si, N, S, with an atomic weight of 57.97, 6.20, 9.81, 2.27, and 0.54 supporting the presence of a group from ETOX and MeAl (Fig. 5 b) results in the detection of strong interaction with encapsulation of pore on the surface of MeAl.

Fig. 5.

EDX spectrum of synthesised

(a) MeAl, (b) E‐MeAl

5.6 Thermal analysis

Fig. 6 a shows a DSC curve, which provided qualitative and quantitative data about the physical state of the material. The MeAl exhibit an endothermic event (94.5°C) attributing to relaxation peak that pursues the glass transition of Al₂ O₃. Whereas the second endothermic peak at 202°C demonstrates the presence of Al₂ O₃. The endothermic peak at 297°C associated with thermal decomposition characterised by an endothermic event which has begun at 297°C and it shows the thermal stability until 280°C.

Fig. 6.

Thermal analysis of synthesised

(a) MeAl, (b) E‐MeAl

The DSC curve of drug‐loaded MeAl (Fig. 6 b) indicated the evidence that small endothermic peak corresponding to the presence of ETOX near 137.5°C. It indicates the melting point of ETOX bound covalently to the substrate resulting in increased stability, as compared with the parent drug molecule which has a melting point of about 134–138°C. One broad endothermic peak at 57.6°C is attributed to the decomposition of organic species and coke combustion reported. The DSC study did not recognise either crystalline drug material in MeAl. Thus the drug fused into MeAl in the amorphous or muddled crystalline phase of molecular dispersion. In this case, the change in the thermo analytical profile indicates a strong dispersion of alumina reinforcing the idea that the drug was entrapped in MeAl.

5.7 Determination of drug content in MeAl

The per cent of drug loading on APTES‐functionalised MeAl was found to be 14%. The loading percentage of ETOX has increased to a maximum of up to 16% with the utilisation of carbodiimide (EDC). A water soluble EDC acts as an excellent coupling agent and easy removal of EDX traces are possible from the final product after aqueous washing treatment.

5.8 Zeta potential

In MeAl, the surface complex is alleged to be non‐protonated or monoprotonated entails that the negatively charged surface complex offers hydrogen bonding possibilities. However, zeta potential inclines negative −1.81 mV and decreased to −17.1 mV. Furthermore, it extends a description to sorption of negatively owed species considering the alumina surface was about neutral to start with entails a broad total of OH groups at the mesoporous surface. However, during the adsorption of the exterior charge becomes more and more negative which resemble ETOX loaded successfully to the surface of MeAl. These successful changes in zeta potential emulate the surface functionalisation (see Fig. 7).

Fig. 7.

Zeta potential results of

(a) MeAl, (b) E‐MeAl

5.9 Particle size

For the quantification of efficacy and therapeutic ability of synthesised mesoporous materials, particle size plays a crucial role and offers a blunt effect on stability, drug release and biodistribution at an effective rate and extent. From the study, it was observed that the particle size of MeAl was found to be 11.04 nm than E‐MeAl 30.18 nm. The mean particle size of MeAl was found to be expanded; this heightened size is in agreement with the literature. This implies the polycondensation reaction is devoted to the interaction that favours the MeAl growth. It represents the ETOX entrapped effectively on the pore void surface of mesoporous material. Lesser the particle size much better the benefit which was also represented in the X‐ray pattern of E‐MeAl. Therefore, we hypothesise that ameliorated size has an attractive interaction between ETOX and MeAl.

5.10 Polydispersity index (PDI)

The results of the PDI of MeAl and drug‐loaded MeAl are shown in Table 1. For monodispersed particles, the PDI should be in the range of 0.2–0.7. Since the PDI of MeAl and drug‐loaded MeAl was found to be 0.393 and 0.683, respectively, from this, it was confirmed that the E‐MeAl particle grew and heightened can simply be imputed to statistical broadening that appears during the progress of polycondensation which was established on the concentration of the precursor. This proposes that the precursor and template a have a higher reactive tendency to yield monodisperse with partial polydisperse particle size distribution hence therefore potentially advisable for building mesopores.

Table 1.

Data of particle size analysis and zeta potential

Sample	Mean particle size, nm	Polydispersity index	Zeta potential, mv
MeAl	11.04	0.393	1.81
E‐MeAl	30.18	0.683	17.1

5.11 BET analysis and nitrogen sorption isotherm

The prepared isotherm showed a straight, flat and curvilinear loop, which corresponds to the mesoporous nature with changes in slop observed at relatively high pressure about P /P _o  = 0.96, which also suggest the formation of little higher macropores in the sol‐gel sample. From the typical hysteresis loop, it supports that larger pore centred was present in MeAl. However, small mesopores are pronounced in addition to large mesopores developed after APTES functionalisation and condensation. Fig. 8 a shows mesoporous alumina displayed Langmuir II type isotherm with unconditional monolayer adsorption. The point P /P ₀ 0.1 at 0.96 cm³ /G STP, the inception of the approximately linear middle section of the isotherm begin to indicate the lap of monolayer coverage. A firm uptake of N₂ as an outcome of capillary condensation is noticed in relative pressure (P /P _o) of 0.02 and grasp to pick height point at 0.096, which propose formed product associated with the mesoporous class.

Fig. 8.

Nitrogen sorption isotherm and corresponding pore size distribution

(a) Nitrogen sorption isotherm, (b) Pore size distribution

Fig. 8 b shows the pore size distribution of synthesised MeAl exploiting Barrett–Joyner–Halenda model (BJHM) unify at 4.3 nm. It demonstrates partitioning of mesopore with nanometre size in the sample which shows a superlative peak at 4.3 nm. Based on research findings, there is a contracted pore size distribution in the range (1–10 nm) of concern for adsorption.

5.12 In vitro dissolution study

The release profile of ETOX from MeAl was explored under two different pH conditions. The present release profile showed pH‐dependent behaviour. The release of E‐MeAl was significantly more intense in neutral pH than low and acidic conditions. At pH 1.2, about 71.44% and at pH 7.4, 89.76% drug release was observed, respectively. The slow release corresponds to limited solubility and hydrophobic interaction at pH 1.2. The improvement in the release profile largely attributed to the porous nature of carrier changing crystalline state to amorphous state, which is known to ameliorate drug solubility and dissolution, whereas gigantic release due to the weakening of electrostatic charges and hydrogen bonding over MeAl leads to a greater release at pH 7.4 (Fig. 9). From the FT‐IR structure, it was confirmed that the covalent bonding between the amine group of APTES and S=O group of ETOX. From the release study, it was well observed that due to the mesoporous nature of formed functionalised material shows porous surface externally embedded with a drug, which has an ability to hold the drug effectively as well. Furthermore, it was observed that the dialysis bag allows the soluble drug and retained the nanoparticles. The concentration of drug released into the receiver compartment was determined by using the UV–Vis spectrophotometer at 284 nm at a subsequent time interval.

Fig. 9.

Comparison of in‐vitro dissolution profile of E‐MeAl at pH 7.4 and pH 1.2

5.13 Cell viability study

Many such inorganic mesoporous nanoparticles containing material cause incompatibility and also cause cellular damage as reported. Nowadays more emphasis is placed on the formation of such nanoparticles used for drug delivery carrier. So newly synthesised inorganic mesoporous materials toxicity is of important consideration and that to validate for any damage to the cellular level is of great need due to the unavailability of toxicity information of such newly synthesised material. The MeAl superiority of ETOX was quantified by IC₅₀ value, which is defined as drug concentration desired to inhibit 50% of incubated cell growth in arranging period. The IC₅₀ value shows that all functionalised concentration exhibited a dose‐dependent cytotoxicity effect towards CHO cell lines. The selected concentration (10–60 µg) is less toxic with respect to the corresponding functionalised MeAl surface may have a positive influence. The result of the cell viability assay showed that the E‐MeAl used in this study was non‐toxic even at a concentration of 60 µg. This result is in good reconciliation with those described in the literature.

During the cytotoxicity study, toxic material representing cell death in the inoculated medium shows the toxic nature of the material. Owing to the porous structure of MeAl has a potential for high loading of biological material. The cell viability study of E‐MeAl was carried out on P89 CHO cell lines at a concentration 10–60 µg. The results illustrated in Fig. 10 determined that E‐MeAl demonstrated superior cell viability activity with lower IC₅₀ (0.10 µg/ml), respectively.

Fig. 10.

Microscopical images of different concentrations of E‐MeAl and control group

The enhanced viability is attributed to improved solubility and stability due to the mesopore inside the core structure of MeAl. The IC₅₀ value for the compound tested was beyond the concentrations tested. Therefore the compound appears to be non‐toxic to the cell line (CHO) against which the cytotoxic activity has been tested.

6 Conclusion

In the present study, the successful casting of model drug ETOX into pores of synthesised MeAl was achieved through functionalisation using APTES, EDC as a catalytic agent and HTAB as a template. The porous architectural framework and textural properties of synthesised MeAl were analysed potentially through TEM, FESEM, XRD, DSC, and EDX. The nitrogen adsorption–desorption isotherm (BET analysis) and BJHM‐based study of MeAl revealed 4.3 nm pore diameter of synthesised alumina confirmed the formation of ordered, nanosized mesoporous nature of MeAl. The success of host–guest chemistry mainly relies on ordered, nanosized porous nature of mesoporous materials and functionalisation reaction. The maximum loading 16% was achieved of therapeutic agent ETOX on functionalised MeAl surface revealed successful incorporation of the guest molecule into the host MeAl. The improved solubility of water insoluble ETOX achieved was revealed through the drug release and analytical investigation. In the future, it may be possible to deliver the present nanoparticles into the biological system as a treatment regime. However, a thorough study is needed to determine the toxicity level of alumina in the human body with a change in surface morphology and texture.