Research Article |
Corresponding author: Praneet Opanasopit ( opanasopit_p@su.ac.th ) Academic editor: Milen Dimitrov
© 2024 Phuvamin Suriyaamporn, Boonnada Pamornpathomkul, Pawaris Wongprayoon, Theerasak Rojanarata, Tanasait Ngawhirunpat, Praneet Opanasopit.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Suriyaamporn P, Pamornpathomkul B, Wongprayoon P, Rojanarata T, Ngawhirunpat T, Opanasopit P (2024) The artificial intelligence and design of experiment assisted in the development of progesterone-loaded solid-lipid nanoparticles for transdermal drug delivery. Pharmacia 71: 1-12. https://doi.org/10.3897/pharmacia.71.e123549
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The application of Artificial Intelligence (AI) has the potential to revolutionize the formulation development of nanomedicine. This study investigated the physicochemical characteristics of progesterone-loaded solid-lipid nanoparticles (PG-SLNs) produced through an emulsification–ultrasonication process, with a focus on demonstrating the efficacy of this controlled preparation method via the Design of Experiments (DoE) and Artificial Neural Networks (ANN). Critical quality factors, including stearic acid, medium chain triglycerides (MCT), Pluronic F-127, and the amount of propylene glycol (PG), were explored using DoE to streamline experimental setups. The concentration of stearic acid was identified as a crucial factor influencing PG-SLN physicochemical properties, impacting particle size (PS), polydispersity index (PDI), zeta potential (ZP), and %drug loading (%DL). Optimal conditions for PS, PDI, ZP, and %DL were identified. DoE revealed acceptable values across multiple runs, and the ANN model demonstrates high prediction accuracy, surpassing Response Surface Methodology (RSM). The selected PG-SLN formulation was tested for transdermal drug delivery, showing improved permeation compared to PG suspension. Loading with limonene further enhances transdermal drug delivery, attributed to limonene’s role as a penetration enhancer. Moreover, the selected PG-SLN formulation was found to be safe and non-toxic to neuronal cells. The combination of DoE and ANN was proposed to enhance predictive ability. This research highlights the potential of PG-SLNs in transdermal drug delivery, emphasizing the role of limonene as a safe and effective enhancer. The study contributes to the growing interest in applying AI tools in pharmaceutical and biomedical fields for improved predictive modeling.
Artificial intelligence, neural network, design of experiment, solid-lipid nanoparticles, progesterone
Progesterone (PG), the inherent progestin, is a significant gonadal hormone primarily synthesized by the ovary in females and by the testes and adrenal cortex in males (
PG belongs to BCS class II, characterized by poor aqueous solubility and labeled as ‘practically insoluble’ according to the solubility classification adopted by USP and Ph. Eur. PG has a log P value of 3.87. Consequently, the therapeutic use of PG was restricted due to its highly hydrophobic nature as a steroid hormone with very low solubility in water (
The application of artificial intelligence (AI) and design of experiments (DoE) methods has the potential to revolutionize the way formulation development is designed and optimized (
This study marked the first-time development of PG-SLN for transdermal drug delivery to slow neurodegenerative disorders in postmenopausal women. This study is still a challenge due to the limited number of research initiatives in this area. The objective of this study was to design and develop PG-SLN using AI and DoE techniques to predict the appropriate formulation for transdermal drug delivery in Alzheimer’s patients.
Micronized progesterone was received from Enviero, Michigan facility (Kalamazoo, USA). Stearic acid, medium chain triglycerides (MCT), Pluronic F-127 and limonene were purchased from Sigma Aldrich (Dorset, UK). Phosphate buffered saline (PBS) solution adjusted pH 7.4 was prepared from 137 M sodium chloride (NaCl), 2.7 mM potassium chloride (KCl), 10 mM sodium phosphate dibasic (Na2HPO4), and 1.8 mM potassium phosphate monobasic (KH2PO4). All chemicals and solvents used were of analytical reagent grade. The fresh neonatal porcine skins were received from the local slaughterhouse (Nakhon Pathom, Thailand).
PG-SLNs were prepared using the emulsification–ultrasonication method. Briefly, stearic acid was melted in a water bath at 80 °C. Subsequently, medium-chain triglycerides (MCT) and PG were added to the molten solid lipid. The homogeneous lipid phase was slowly dropped and dispersed into the aqueous phase, containing Pluronic F-127, at 80 °C using a probe sonicator (PRO Scientific Inc., VCX 130 PB sonicator and 3 mm microtip, Oxford, USA) at 40 Hz for 20 minutes. The resulting lipid dispersion was cooled down in an ice bath to obtain PG-SLN. Finally, the excess lipid and PG were centrifuged (Eppendorf™ Centrifuge 5810R, Hamburg, Germany) at 12,000 rpm, 4 °C for 10 minutes. Seventy-seven different formulations, guided by DoE, were prepared by varying the critical quality factors, following in Table
The particle size (PS), polydispersity index (PDI), and zeta potential (ZP) of the PG-SLNs were measured using dynamic light scattering (DLS, Zetasizer Nano Series, Malvern Instruments, DTS version 4.10). Before measurement, the PG-SLNs were appropriately diluted with deionized (DI) water and mixed using a vortex mixer to obtain a homogeneous formulation. Subsequently, the formulations were filled into a disposable folded capillary cell and measured. The morphology of PG powder and selected PG-SLN was observed under the scanning electron microscope (SEM, Mira TC, Czech Republic) at a beam voltage of 15.0 kV with 10 kx magnification. The particle size of PG-SLN was measured in diameter and compared with DLS results.
The analysis of the PG amount was conducted using HPLC. The PG-SLNs were appropriately diluted with methanol and filtered through a 0.45-µm syringe filter. Chromatographic separation was achieved using a Zorbax Eclipse XDB-C18 column (250×4.6 mm, 5 μm pore size, Agilent, USA), maintained at 30 °C. The mobile phase consisted of 90%v/v methanol and 10%v/v ultrapure water at a flow rate of 1 mL/min, with detection performed at a wavelength of 240 nm. The retention time was approximately 4.4 min [4]. The percentage of drug loading (%DL) was calculated from Equation 1.
(1)
The screening study was conducted to identify critical quality factors. The components of PG-SLNs were the main factors affecting PS, PDI, ZP, and %DL in SLNs. A central composite design (CCD) with four experimental factors was investigated in Table
According to the DoE analysis, the dataset was used as input factors to generate a prediction model. The PS, PDI, ZP, and %DL were used as output factors. To create a pattern recognition model of the ANN architecture, two hidden layers with 5 and 2 neurons, respectively, were created. Before generating the prediction model, the dataset was appropriately cleaned and normalized to avoid significant biases. Cross-validation was applied to the dataset before training and testing the ANN, with a ratio of 70% for training and 30% for testing. Therefore, the number of data points for training and testing was 54 and 23, respectively. The learning rate was set at 0–1.2, with a momentum of 0.8, and the training cycle was set to 1–1200. These hyperparameters were defined after reaching an R2 value of over 0.85. To evaluate the prediction model, the 11 experiments of PG-SLNs at various stages in the DoE were applied to the prediction model to generate predicted outputs (Suppl. material
(2)
The in vitro transdermal drug delivery of PG suspension, optimal PG-SLNs, and optimal PG-SLNs with 2% limonene, each containing an equal drug amount, was conducted using a Franz-diffusion cell. Limonene was employed as a skin enhancer. Neonatal porcine skin was isolated from the subcutaneous layer and cleansed with phosphate buffer saline (PBS, pH 7.4). In the Franz-diffusion cell, the receiver compartment was filled with PBS (pH 7.4) and maintained at a constant temperature of 37±0.5 °C with continuous stirring. The neonatal porcine skin was affixed to the receptor compartment, with the epidermis facing upward toward the donor compartment. Each formulation (1 ml) was added to the donor compartment. Samples (0.5 ml each) were collected from the receptor compartment at predetermined time intervals (0, 0.5, 1, 2, 4, 6, 8, 12, 24, 48 and 120 h) and replaced with an equivalent amount of PBS (pH 7.4) to maintain a sink condition. After transdermal drug delivery, the porcine skin was sliced into small pieces and extracted in 10 ml of methanol using probe sonication (40 Hz). The collected samples were filtered before analysis by HPLC. The percentage of PG permeation versus time and percentage of PG remaining in the skin for each formulation were plotted and reported, respectively. The %PG permeation and % PG remaining in the skin were calculated following Equation 3 and 4, respectively.
(3)
(4)
The skin permeation profiles parameters, which elucidated how PG behaved in delivering across skin tissue. Parameters such as cumulative PG amount over 120 h per area (Q120/A), flux (J), lag time (tlag), diffusion coefficient (Kd), and permeability coefficient (Kp) have been reported. J and tlag can be determined by analyzing the slope and intercept on the time-axis graph of Q120/A versus time, respectively. The diffusion coefficient (Kd) and permeability coefficient (Kp) were calculated using equations Equation 5 and 6, respectively.
(5)
(6)
Meanwhile, h represents the thickness of the skin tissue, and Cd denotes the concentration of PG in the donor.
The cytotoxicity of PG-suspension, optimal PG-SLNs and PG-SLNs with 2% limonene were determined using an MTT test against SH-SY5Y cells, a human neuroblastoma cell line. The day before the experiment, SH-SY5Y cells were seeded onto 96-well plates at a density of 10,000 cells/well with Dulbecco’s modified Eagle’s medium (DMEM) supplemented with 10% fetal bovine serum and grown at 37 °C in a humidified 5% CO2 incubator. After 24 h of incubation, different concentrations of each formulation were added to each well and incubated for an additional 24 h. Following treatment, the cytotoxicity of all formulations was assessed using MTT solution at a final concentration of 1 mg/mL in each well for 3 h. After removing the media, the formazan crystals in the cells were dissolved by adding 100 µL of dimethyl sulfoxide (DMSO) to each well. The optical density (OD) of each well was measured using an automated microplate reader (Multimode plate reader, Model Victor NivoTM, PerkinElmer, Hamburg, Germany) at 550 nm. The percentages of cell viability of SH-SY5Y cells were calculated using Equation 7. The control group (DI water) was assumed to have 100% cell viability, serving as the baseline.
(7)
To evaluate the stability of the optimal PG-SLNs and PG-SLNs with 2% limonene, they were stored at 5 °C ± 3 °C, 25 °C ± 2 °C/60%RH ± 5%RH and 40 °C ± 2 °C/75%RH ± 5%RH for 3 months according to the ICH guideline section Q1A R2. The physical appearance, PS, PDI, ZP and drug content were performed at 0, 1, 2 and 3 months.
The DoE process for screening critical quality factors was analyzed in Design Expert version 11. The prediction model generated by ANNs was developed using RapidMiner Studio version 10.3 and PyCharm version 2023.3.2, utilizing the scikit-learn library (
A screening of critical quality factors was conducted in this study. Based on a previous study, the important factor that mostly affected the physicochemical properties was the component of SLN and drug loading. Seventy-seven combinations of PG-SLN were considered in terms of PS, PDI, ZP, and %DL, generated by DoE software. All factors were significant to the outcome. Fig.
Recently, the application of ANN has been employed to perform more intricate analyses and overcome specific constraints associated with the DoE methodology. ANNs can analyze complex data, identify patterns, and generate prediction models that surpass those of DoE, which relies only on polynomial bases of degree 1 or 2. Furthermore, multiple outputs can be predicted simultaneously within the same model (
Predicted values and experimental results from prediction model of PS, PDI, ZP and %DL.
Experiment | PS (nm) | PDI | ZP (mV) | %DL (%) | ||||
---|---|---|---|---|---|---|---|---|
Actual | Predict | Actual | Predict | Actual | Predict | Actual | Predict | |
1 | 368.01 | 337.74 | 0.22 | 0.14 | -33.73 | -29.16 | 87.04 | 114.16 |
2 | 342.10 | 330.82 | 0.29 | 0.38 | -33.52 | -36.34 | 76.83 | 60.56 |
3 | 350.24 | 332.01 | 0.29 | 0.38 | -33.88 | -36.40 | 78.51 | 67.38 |
4 | 354.37 | 337.47 | 0.21 | 0.23 | -33.76 | -35.13 | 62.28 | 45.92 |
5 | 318.30 | 340.48 | 0.14 | 0.29 | -32.39 | -39.25 | 40.77 | 43.72 |
6 | 300.37 | 303.48 | 0.19 | 0.39 | -31.87 | -32.24 | 38.26 | 35.80 |
7 | 313.04 | 298.16 | 0.22 | 0.15 | -30.44 | -27.63 | 79.26 | 109.36 |
8 | 332.70 | 336.74 | 0.22 | 0.36 | -32.78 | -36.49 | 56.99 | 64.94 |
9 | 318.09 | 335.70 | 0.17 | 0.27 | -31.89 | -38.17 | 53.64 | 62.84 |
10 | 325.23 | 336.03 | 0.22 | 0.34 | -32.51 | -32.90 | 55.22 | 60.92 |
11 | 290.18 | 310.02 | 0.29 | 0.43 | -31.80 | -28.61 | 64.72 | 37.98 |
RMSE | 8.636±4.217 | 0.038±0.015 | 1.943±1.054 | 0.767±0.567 |
The PG-SLN was composed of 5% stearic acid + 1.76% MCT + 0.30% Pluronic F-127 + 0.5% PG from predicted model was selected for skin permeation study and neural cell viability. The PS, PDI, ZP, and %DL were 368.01±2.98 nm, 0.22±0.01, -33.73±1.23 and 87.04±17.43%, respectively. The morphology of the selected PG-SLN under SEM revealed a spherical shape, as illustrated in Fig.
The results of transdermal drug delivery and the remaining drug from the selected PG-SLN (5% stearic acid + 1.76% MCT + 0.30% Pluronic F-127 + 0.5% PG) were shown in Fig.
The skin permeation profile results were presented in Table
Skin permeation profile# | Formulations | ||
---|---|---|---|
PG suspension | PG-SLN | PG-SLN with 2% limonene | |
tlag (h) | 5.33±1.16 | 2.33±1.53 | 0.53±0.06* |
J (µg/cm2/h) | 4.68±0.57 | 18.48±7.30 | 95.17±30.45* |
Q120/A (µg/cm2) | 55.27±6.05 | 221.89±88.80 | 1122.37±402.43* |
Kd (×10−3, cm2/h) | 5.19±1.28 | 15.56±10.18 | 50.37±5.13* |
Kp (cm2/h) | 0.94±0.11 | 3.70±1.46 | 19.03±6.09* |
The viability results of SH-SY5Y cells treated with PG-suspension, optimal PG-SLNs, PG-SLNs with 2% limonene, and the control were reported in Fig.
The stability of optimal PG-SLNs and PG-SLNs with 2% limonene was studied for 1, 2, and 3 months at 4, 25, and 40 °C under controlled humidity. The results showed that the physical appearance of both formulations did not change, with no separation or precipitation observed from initiation over the 3-month period. Additionally, PS, PDI, ZP, and drug content were reported as non-significantly changed from 0 to 3 months under every storage condition, as represented in Table
The stability results of the optimal PG-SLNs and PG-SLNs with 2% limonene.
Stability period (month) | Temp (°C) | Stability parameters observed | |||||||
---|---|---|---|---|---|---|---|---|---|
PS (nm) | PDI | ZP (mV) | Drug content (%w/w) | ||||||
PG-SLNs | PG-SLNs with 2%limonene | PG-SLNs | PG-SLNs with 2%limonene | PG-SLNs | PG-SLNs with 2%limonene | PG-SLNs | PG-SLNs with 2%limonene | ||
0 | - | 368.01±2.98 | 388.01±1.12 | 0.22±0.01 | 0.21±0.03 | -33.73±1.23 | -30.11±1.28 | 0.50±0.00 | 0.51±0.01 |
1 | 4 | 252.50±2.26 | 258.50±6.82 | 0.11±0.01 | 0.12±0.01 | -39.00±0.46 | -33.28±5.64 | 0.46±0.00 | 0.50±0.02 |
25 | 301.80±2.80 | 258.70±4.96 | 0.17±0.01 | 0.14±0.04 | -35.24±-.52 | -31.23±0.31 | 0.50±0.01 | 0.49±0.03 | |
40 | 384.20±9.03 | 323.30±6.11 | 0.31±0.02 | 0.32±0.06 | -32.90±0.69 | -28.43±0.18 | 0.50±0.02 | 0.52±0.04 | |
2 | 4 | 240.63±0.81 | 392.37±5.40 | 0.15±0.01 | 0.22±0.03 | -32.50±3.29 | -28.40±2.44 | 0.53±0.02 | 0.51±0.02 |
25 | 268.33±0.67 | 366.87±8.46 | 0.12±0.01 | 0.21±0.01 | -32.63±0.76 | -30.63±3.88 | 0.49±0.02 | 0.50±0.01 | |
40 | 282.80±1.66 | 331.40±8.37 | 0.24±0.02 | 0.26±0.03 | -25.93±0.60 | -31.23±1.05 | 0.51±0.01 | 0.51±0.01 | |
3 | 4 | 370.60±4.79 | 325.40±5.06 | 0.19±0.05 | 0.26±0.04 | -29.30±2.80 | -31.07±2.41 | 0.48±0.04 | 0.51±0.02 |
25 | 334.33±8.66 | 320.07±9.56 | 0.22±0.03 | 0.27±0.03 | -30.63±4.48 | -32.85±3.38 | 0.50±0.01 | 0.52±0.03 | |
40 | 297.64±4.48 | 282.37±6.65 | 0.25±0.06 | 0.30±0.00 | -31.67±2.68 | -30.78±2.43 | 0.51±0.02 | 0.50±0.02 |
This study explored the physicochemical characteristics of PG-SLNs during production, employing an emulsification–ultrasonication process. The objective was to demonstrate the efficacy of this controlled preparation method for advanced experimental designs and data analyses such as DoE and ANN. Critical quality factors included the components of PG-SLN (stearic acid, MCT, and Pluronic F-127) and the amount of PG. DoE was utilized to streamline the experimental setup by screening these critical quality factors. The main factor influencing the physicochemical properties of PG-SLN was the concentration of stearic acid. As a solid lipid with high molecular weight, increasing its concentration led to an increase in PS (
For optimal conditions and dataset generation for prediction, the PS should range from 20 to 100 nm to enhance drug permeation through the skin (
Subsequently, 11 different runs were conducted using DoE to compare predicted outcomes, revealing acceptable values for PS, PDI, ZP, and %DL under all tested conditions. The adjustment of the learning rate helps increase the RMSE value; however, when the learning rate is adjusted too high, it may lead to a decrease in RMSE. This is because a higher learning rate causes the model to learn quickly but may skip local minimum points, making the model unstable (
The selected PG-SLN (5% stearic acid + 1.76% MCT + 0.30% Pluronic F-127 + 0.5% PG) was utilized to assess transdermal drug delivery. The results indicated that PG-SLN exhibited higher permeation compared to PG suspension, attributed to the small PS of the drug that can penetrate through the gap junctions between skin tissues (approximately 50–400 µm) (
The neuroprotective effects of PG and its derivative have been demonstrated in various experimental models of neurodegenerative diseases. For instance, in a study involving ovariectomized female 3×Tg-AD mice, which serve as a model for Alzheimer’s disease, the administration of PG alone or in combination with estradiol over a period of 3 months specifically mitigated the hyperphosphorylation of Tau (
In the cytotoxicity assessment of SH-SY5Y cells, a human neuroblastoma cell line, the results indicated that concentrations exceeding 1 μg/mL showed toxicity to SH-SY5Y cells. This outcome could be explained by high concentrations of progesterone potentially inducing off-target effects or interactions with other cellular components, thereby disrupting normal cellular functions and leading to toxicity (
The primary limitation of this study was the relatively small dataset available for training the prediction model. However, this limitation can be addressed through cross-validation to avoid overfitting of the model (
This study reported the use of DoE and ANN together to create a predictive model for PG-SLNs formulation, produced through the emulsification–ultrasonication method, intended for transdermal drug delivery to relieve neurodegenerative disorders in postmenopausal women. Critical quality factors included the components of PG-SLN (stearic acid, MCT, and Pluronic F-127) and the amount of PG. DoE streamlined the experimental setup by screening these factors, showing stearic acid concentration as a key influencer of physicochemical properties. For optimal conditions, PS should range from 20 to 100 nm, PDI below 0.2, and ZP exceeding ±30. ANN exhibited high prediction accuracy over RSM, handling multiple outcomes simultaneously, unlike DoE’s polynomial models. Despite limitations in dataset size, the study’s findings provide valuable insights into optimizing PG-SLNs for enhanced drug delivery and therapeutic efficacy. In comparison to traditional methods, this approach required fewer resources and time, accelerating the production process. The selected PG-SLN (5% stearic acid + 1.76% MCT + 0.30% Pluronic F-127 + 0.5% PG) showed enhanced transdermal drug delivery compared to PG suspension, particularly when loaded with limonene. Limonene improved drug permeation through the skin barrier, with concentrations less than 2% being safe and effective. Consequently, AI enabled the prediction of distinct characteristics and intricate behaviors of nanomaterials. The integration of advanced tools like ANN holds significant promise in advancing the field of nanomedicine, generating new knowledge, and impacting future development.
This research was supported by the National Research Council of Thailand (NRCT: N42A650551).
The authors declare no competing interests.
Phuvamin Suriyaamporn: methodology, software, formal analysis, investigation, data curation, and writing-original draft preparation. Boonnada Pamornpathomkul: visualization, proofreading, and editing. Pawaris Wongprayoon: methodology, formal analysis. Theerasak Rojanarata: validation, proofreading, and editing. Tanasait Ngawhirunpat: resources, and funding acquisition. Praneet Opanasopit: conceptualization, supervision, resources, and funding acquisition. All authors have read and agreed to the published version of the manuscript.
This research was supported by Silpakorn University under the Postdoctoral fellowship program.
Dataset of formulation
Data type: docx
Explanation note: Dataset of PG-SLN and 11 experiments of PG-SLNs at various stages in the DoE.