Synthesis and Characterization of Tadalafil Nanoparticles by Hydrothermal Method

doi:10.21203/rs.3.rs-2635081/v1

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Synthesis and Characterization of Tadalafil Nanoparticles by Hydrothermal Method

https://doi.org/10.21203/rs.3.rs-2635081/v1

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Tadalafil (TDFL) nanocrystals, a weakly water-soluble medication, were effectively produced using a hydrothermal method to improve solubility and dissolving rate. Tween 80 was chosen as an effective surfactant for inhibiting aggregation during the stabilization of medication nanocrystals. Under ideal circumstances, nearly spherical nanocrystals with a mean particle size of 284 nm were produced. The FTIR study revealed that the precipitated nanoparticles had the same chemical structure as the raw TDFL, and scanning electron microscopy (SEM) revealed that the TDFL Nano agglomerates. When compared to the unprocessed medication, differential scanning calorimetry (DSC) analysis revealed no significant crystalline alteration in the nanocrystals. Furthermore, as compared to the raw material, the dissolution rate of the processed TDFL nanocrystals in 120 minutes was considerably higher. As a result, it was determined that hydrothermal might be a straightforward and effective approach for producing poorly water-soluble drug particles with reduced particle size, narrow particle size distribution, and increased dissolving characteristics. The current work presents a forthright technique for synthesizing and scheming nanosized TDFL for improved drug delivery applications that do not require the use of organic solvents, is green, and has a high yield as a single-step procedure.

Nanoparticles

Tadalafil

Hydrothermal

Solubility.

One of the most prevalent ways for preparing nanomaterials is hydrothermal synthesis. It is essentially a solution-reaction method. The production of nanomaterials in hydrothermal synthesis may occur over a wide range of temperatures, from ambient temperature to very high temperatures. Depending on the vapor pressure of the primary component in the reaction, either low-pressure or high-pressure conditions can be employed to regulate the morphology of the materials to be produced. Using this method, several different types of nanomaterials have been successfully produced. The hydrothermal synthesis process has considerable benefits over other methods [1–4]. Nowadays, nanomaterial synthesis processes with low cost as well as low environmental impact are gaining importance for different industries [5]. Hydrothermal synthesis can result in nanomaterials that are unstable at high temperatures. The hydrothermal technique may be used to create nanomaterials with high vapor pressures while causing minimal material loss. Through liquid phase or multiphase chemical processes, the compositions of nanomaterials to be produced may be tightly controlled in hydrothermal synthesis [2]. This technique is becoming one of the most important tools for advanced materials processing, particularly owing to its advantages in the processing of nanostructural materials for a wide variety of technological applications such as electronics, optoelectronics, catalysis, ceramics, magnetic data storage, biomedical, bio photonics, etc [6]. In recent years, commercial interest in hydrothermal synthesis was revived because few materials with improved properties have emerged that can be prepared under mild conditions of temperature and pressure. Hydrothermal synthesis is a novel method that yields nanoparticles with narrow particle size distribution and high purity without further treatment [7–11]. Approximately 40% or more of the new chemical entities being generated through drug discovery programs are poorly water-soluble. The majority of drugs have low bioavailability which is mainly accounted for due to poor aqueous solubility. To achieve greater bioavailability, there is a need for enhancement solubility of the drug [2, 4, 12] Various approaches are carried out to enhance the solubility of the drugs. One such approach is via particle size reduction by synthesis of drug nanoparticles [13]. Nanosized drug particles exhibit greater solubility and hence dissolution rate as compared to an original drug [14, 15]. This could be due to the reduced particle size of drug particles which results in an increase in the effective surface area of the drug for dissolution. Tadalafil is a carboline-based compound with vasodilatory activity. It selectively inhibits the cyclic guanosine monophosphate (cGMP)-specific type 5 phosphodiesterase-(PDE-5)-mediated degradation of cGMP and is used for the treatment of erectile dysfunction, benign prostatic hyperplasia, and pulmonary arterial hypertension. It belongs to Class II of the categorization system, low water solubility and wettability are significant issues, and despite high permeability, its bioavailability is restricted by solubility and dissolution rate [4, 16–18]. In this study, nanoparticles were prepared by hydrothermal synthesis using TDFL prepared TDFL nanoparticles were characterized by particle size analysis, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray powder diffraction, and in vitro release study. Solubility measurement was performed to demonstrate the effect of size reduction on the solubility of TDFL.

Materials

Tadalafil and Tween 80® were acquired from Sigma Aldrich, whereas all other compounds were analytical grade reagents that were utilized as-is.

The nanometer-sized TDFL is synthesized by a hydrothermal technique using a fully automatic vertical autoclave. A briefly supersaturated solution of the TDFL in distilled water was prepared by placing an excess TDFL in distilled water. The saturated solution was then transferred into a stainless-steel autoclave (Model No. #7441STWL, Medica Instrument Mfg. Company). The autoclave was sealed and maintained at 121°C and 15 PSI pressure for 3 h. After hydrothermal processing, the autoclave was allowed to cool down to room temperature naturally. The resulting precipitate was collected and washed with deionized water several times and dried at room temperature. Under identical experimental conditions, Tween 80® was also used as surfactants to observe its effects on size and solubility.

4.1 Particle size (PS) and zeta potential (ZP) measurements

Based on dynamic light scattering, particle size and polydispersity index (PDI) were measured using a (Malvern Zetasizer Nano ZS 90 UK). In brief, a dilute solution of nano-sized TDFL in double-distilled water was produced. Size measurements were taken after dilution (100 times) of the nano-sized TDFL in water at 25°C. At 25°C, the ZP was likewise measured in the same equipment. In deionized water, the nanoparticles were distributed. The dispersion was then loaded into zeta cells and placed in the zeta sizer. [19, 20].

4.2 Surface morphology

For morphology study of nano-sized TDFL scanning electron microscopy (JSM 6390, Japan). was used. The sample was dusted onto double-sided tape on an aluminum stub and coated with gold using a cold sputter coater to a thickness of 400°A before being scanned with a 20 kV electron beam at various magnifications [21].

4.3 Differential scanning calorimetric studies (DSC)

A differential scanning calorimeter was used for the thermal study (METTLER Toledo DSC 822c Zurich, Switzerland). In an aluminum pan, about 2 mg of each sample was put. Heating and cooling scans were carried out in a dry N2 environment from 40°C − 400°C at heating and cooling speeds of 10°C/min. As a guide, an empty aluminum pan was utilized. The DSC thermograms were used to compute the melting temperature and enthalpy (Fig. 4).

4.4 X-ray diffraction studies (XRD)

To determine the crystalline structure of the nanosized TDFL formulation, an XRD analysis was performed. An X-ray diffractometer was used to acquire patterns of native TDFL and nanosized TDFL (Brucker AXS D8 Advance). The tests were taken at a voltage of 40 kV and a current of 25 mA. All samples were measured in the 2 angle range of 20 ° to 60 ° at a scanning rate of 3°/min and a step size of 0.02 ° [22].

4.5 Fourier transformed infrared (FTIR)

FTIR technique was applied to determine the molecular structures of raw TDFL and the interaction between stabilizer and drug nanocrystals. FTIR spectra were recorded by FTIR spectrometer (8400 S, Shimadzu, Japan) within the spectral region of 400 and 4000 cm⁻1 at a resolution of 2 cm ⁻1. The IR spectra were obtained in a KBr disc.

4.6 Solubility study of TDFL and nanosized TDFL

To investigate the influence of hydrothermal treatment on the formulation's aqueous solubility, an equal amount of native TDFL and nanosized TDFL were dissolved in water. Native TDFL and nanosized TDFL were produced in 10 ml water and incubated for 24 hours in a shaker spinning at 100 rpm, at 37°C (Remi Lab, India). After 24 hours, the aforementioned solution was filtered, and the solubility of TDFL was determined using UV-Visible spectroscopy at 284 nm [15].

4.7 In vitro drug release study

In vitro drug release study of raw TDFL nanocrystals was performed using the USP apparatus II (paddle) technique. As the dissolving media, phosphate buffer (pH 7.4) was employed. The stirring speed and bath temperature were set at 100 rpm and 37.0 ± 0.5°C, respectively. Unprocessed TDFL (2 mg) and TDFL nanocrystals (containing 2 mg tadalafil) were mixed into 900 mL of dissolving media. After 10, 20, 30, 45, 60, 90, and 120 minutes, aliquots of 5 mL were removed and replaced with the same volume of phosphate buffer.

To establish an optimal formulation for obtaining tiny size and increased TDFL solubility, we synthesized nanosized TDFL (through a hydrothermal method) to achieve maximal solubility without the usage of excipients. Following the end of the hydrothermal process, the light-yellow solid products were washed with methanol, filtered, and then air-dried in a laboratory oven at 60°C.

5.1 Particle size analysis

The TDFL nanoparticles had an average diameter of 778.7 nm and were nicely formed. To decrease the particle size of the TDFL, Tadalafil nanoparticles were produced at 121°C. The particle size changes are seen in (figure. 1) From 778.7 to 143.1 nm, the particle size of the TDFL dropped linearly. The polydispersity index (PDI) of nanosized TDFL was less than 0.3. Surfactants, which may adsorb on certain crystallographic faces, as well as solvents that adsorb similarly and control solubility, can potentially affect the size. Surfactants were used to reduce the agglomeration size to about 284 nm [23].

5.2 Zeta potential measurement

The Zeta Potential is an essential tool for analysing the charge on the surface and forecasting the long-term stability of the nanoparticle. The ZP is an essential and helpful indication for predicting the stability of a material when subjected to stress heat and hydrolytic conditions. The ZPs of TDFL and nanosized TDFL with surfactant were determined to be -14.5 mV, -16.0 mV, and − 16.4 mV respectively (Fig. 2). The nanoparticle's ZP values generally ranged from + 100 to -100 mV. Nanoparticles having ZP values more than + 25 mV or less than − 25 mV exhibited a high degree of stability. The ZP tests revealed no significant difference in the ZP value of the TDFL and that of the nanosized TDFL, implying that there was no change in the material's stability following hydrothermal processing.

5.3 Surface morphology

The SEM pictures of the nanosized TDFL produced utilizing the hydrothermal method are shown in Fig. 3. Along with the agglomerates, the product included irregular nanoparticles with indistinct surfaces. The addition of a surfactant to the synthesis system did not affect the surface morphology of nanosized TDFL.

5.4 Differential scanning calorimetric studies (DSC)

The endothermic peak of native TDFL was estimated to be at 299.26°C. We examined the DSC thermograms of natural TDFL and hydrothermally produced TDFL nanoparticles. In nanoparticulate TDFL, a comparable distinctive peak was found. It was discovered that there was no significant change in the thermogram peak following the hydrothermal treatment of the TDFL, suggesting that there were no physicochemical and polymorphism alterations.

5.5 X-ray diffraction study (XRD)

The XRD analysis was then carried out to further understand the nature of the TDFL nanoparticles produced as a result of the hydrothermal treatment (figure. 5b). The distinctive peaks of native TDFL displayed the features of high crystalline structure as illustrated in (Fig. 5a). The XRD peak of bulk TDFL and TDFL nanoparticles are displayed in (Fig. 5a and 5b), the average crystal size (d) was calculated based on the width of the peak by using the Scherrer’s formula: d = 0.94 λ / β cos θ

Where, λ is the wavelength of X-ray used β is the full width at half maximum and θ is the Bragg’s angle of reflection. The average crystallite domain size was found to be 41 nm. No significant difference in the intensity of the diffraction peaks of the samples is closely related to the degree of crystallinity of the samples after the hydrothermal treatment of the TDFL.

5.6 FTIR Studies

The FTIR study was further carried out to understand which functional groups present in the spectra of TDFL nanoparticles formed as a result of hydrothermal treatment. The FTIR spectra of TDFL (figure. 6) show peaks from 400 to 4000 cm-1 was used to analyse the probable intermolecular interactions between tadalafil and the excipients, as well as the molecular structures of an unprocessed drug, nanoparticles, and Tween 80. 793 cm-1 (benzene), 1041 cm-1 (C-O-C stretching), 1490 cm-1 (C-N stretching), 1677 cm-1 (C = C aromatic), 1677 cm-1 (C = O), and 3328 cm-1 were the major distinctive peaks of raw TDFL (N-H stretching). Furthermore, FTIR spectra of Tween 80 revealed four peaks at about 1110 cm-1 (C-O stretching), 1723 cm-1 (C = O stretching), 2904 cm-1 (C-H stretching), and 3328.28 cm-1 (O-H stretching). The FTIR spectra of raw TDFL and TDFL nanocrystals were comparable in peak pattern and frequency, indicating that there was no change in the chemical structure of the drug and no interaction between drug and surfactant.

5.7 Solubility studies

Solubility studies of resultant nanosized TDFL were carried out to confirm the effect of hydrothermal treatment on the solubility of TDFL. The solubility of native TDFL was 3.756 7.425 µg/ml and that of nanosized TDFL was 18.18 µg/ml, demonstrating that hydrothermal treatment of TDFL results in a 2-fold increase in solubility, which could be attributed to a reduction in particle size of native TDFL.

5.8 In vitro release study

In vitro release of pure drug and that of synthesized nanoparticles (figure. 6) shows the comparison of release between pure drug and synthesized nanoparticles. There was an increase in drug release of drug nanoparticles as compared to that of pure drugs. This was attributed mainly due to an increase in surface area due to particle size reduction. The enhanced drug dissolution rate for TDFL was found to be 79.54% (figure. 7 and Table. 1).

The improvement in water solubility and stability would propel TDFL to the forefront of anticancer treatment drugs already on the market. In conclusion, we used a simple hydrothermal method to create nanosized TDFL with an average particle size of less than 300 nm. The presence of crystalline nanosized TDFL was verified by XRD and DSC, which showed that hydrothermal treatment, did not affect the physical or polymorphic form of native TDFL. As a result, the hydrothermal technique may be regarded as a method for producing medication particles with nanoscale size and enhanced solubility while preserving polymorphic shape and stability.

Acknowledgment

One of the authors (Hitendra S. Mahajan) is thankful to University Grant Commission for providing financial assistance under Research Award Scheme (F.301/2014(SAII)/RA201416OBMAH5821).

Ethical Approval-NA

Competing interests

The authors declare no competing interests.

Authors' contributions

KP-project management, writing, editing SMC-Writing original manuscript, editing, supervision HSM- Concept, writing original manuscript, editing, supervision, approval of the manuscript.

Funding

This study received financial support from University Grant Commission for providing financial assistance under Research Award Scheme (F.301/2014(SAII)/RA201416OBMAH5821).

Availability of data and materials

All data and materials are available on request

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Table.1 In vitro drug release of Pure drug, hydrothermal treatment, and hydrothermal surfactant drugs

Drug	Drug Treatment
Drug	Pure Drug	HT plain	HT surfactant
Tadalafil	38.46%	54.88%	79.54%

No competing interests reported.

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Synthesis and Characterization of Tadalafil Nanoparticles by Hydrothermal Method

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Version 1

Abstract

Figures

1. Introduction

2. Materials And Methods

3. Preparation Of Tadalafil Nanoparticles

4. Physical Characterization Of Nano-sized Tdfl

4.1 Particle size (PS) and zeta potential (ZP) measurements

4.2 Surface morphology

4.3 Differential scanning calorimetric studies (DSC)

4.4 X-ray diffraction studies (XRD)

4.5 Fourier transformed infrared (FTIR)

4.6 Solubility study of TDFL and nanosized TDFL

4.7 In vitro drug release study

5. Results And Discussion

5.1 Particle size analysis

5.2 Zeta potential measurement

5.3 Surface morphology

5.4 Differential scanning calorimetric studies (DSC)

5.5 X-ray diffraction study (XRD)

5.6 FTIR Studies

5.7 Solubility studies

5.8 In vitro release study

6. Conclusion

Declarations

References

Tables

Additional Declarations

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