Abstract
Objectives
The objective of this study was to evaluate the effects of temperature, light, pH, reducing agents, oxygen, dilution, syringe material, solvents, and operator differences on the labeling efficiency of 99mTc-radiopharmaceuticals.
Methods
Five GE Healthcare kits ([99mTc]Tc-HMPAO, [99mTc]Tc-MAA, [99mTc]Tc-DMSA, [99mTc]Tc-DTPA, and [99mTc]Tc-tin colloid) were reconstituted with 99mTc-pertechnetate in saline and tested under varying conditions.
Results
Labeling efficiency was largely unaffected, except for [99mTc]Tc-HMPAO, which showed significant reductions with temperature changes (p < 0.001). UV light significantly degraded labeling in all kits (p < 0.001), and pH changes reduced [99mTc]Tc-DMSA efficiency.
Conclusion
Stability depends on optimized formulation, storage, and preparation, and shelf-life extension may be feasible under controlled conditions.
Keywords: Technetium-99m radiopharmaceuticals, Labeling efficiency, Temperature, Light, Reductants
Highlights of the Study
The labeling efficiency and stability of technetium-99m radiopharmaceuticals may be jeopardized by different factors.
The exposure to ultraviolet light significantly degraded the labeling efficiencies of the tested radiopharmaceuticals.
No significant changes in the labeling efficiency were observed after exposure to different ranges of temperature, oxygen, and dilution.
Suppliers can extend the shelf life for these studied kits.
Introduction
Technetium-99m (99ᵐTc) is the most widely used radionuclide in diagnostic nuclear medicine due to its ideal physical properties, including a 6-h half-life and gamma emission suitable for SPECT imaging [1–3]. Its broad clinical utility is supported by the availability of commercial lyophilized kits, which are reconstituted on-site using generator-eluted 99ᵐTc-pertechnetate ([99ᵐTc]NaTcO4) following manufacturer protocols. These protocols address formulation, quality control (QC), and critical preparation parameters such as temperature, pH, reductants, and light sensitivity. Achieving high labeling efficiency is essential for ensuring the safety, efficacy, and diagnostic performance of 99ᵐTc-labeled radiopharmaceuticals. Factors such as the quality of the eluate, kit composition, and preparation conditions including reaction temperature, pH, and reducing agent play a pivotal role. Poor labeling can result in impurities such as unbound pertechnetate or hydrolyzed reduced technetium ([99ᵐTc]TcO2), compromising radiochemical purity (RCP) and image quality [1–3].
QC methods, including thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC), are routinely used to assess RCP and detect impurities. External factors such as storage temperature, humidity, and light exposure can also influence labeling outcomes [4, 5]. Prior studies have highlighted the impact of environmental and formulation-related variables on the stability and purity of radiopharmaceuticals like [99ᵐTc]Tc-MIBI and [99ᵐTc]Tc-ECD [4–6]. Advances in automation, microfluidic systems, and artificial intelligence have further refined the production and QC of radiopharmaceuticals, improving reproducibility and minimizing human error. These innovations offer greater control over reaction parameters, enhance labeling yields, and help maintain consistent product quality.
This study aimed to evaluate how preparation conditions specifically temperature, pH, and reaction conditions affect the labeling efficiency of five 99ᵐTc-based radiopharmaceutical kits: Ceretec, Pulmotech, Succimer, Draximage DTPA, and Tin colloid. Understanding these factors will support better standardization of preparation practices and contribute to improved diagnostic reliability in clinical nuclear medicine.
Materials and Methods
All materials and methods followed the manufacturers’ instructions, serving as the reference for production and QC to maintain radiopharmaceutical integrity. Equipment, including the 99Mo-99mTc generator and dose calibrator, was qualified and periodically re-calibrated to ensure safety and accuracy. Five GE Healthcare kits: (1) Ceretec [99mTc]Tc hexamethylpropylene amine oxime ([99mTc]Tc-HMPAO), (2) Pulmotech [99mTc]Tc macroaggregated albumin ([99mTc]Tc-MAA), (3) Succimer [99mTc]Tc-meso-2,3-dimercaptosuccinic acid ([99mTc]Tc-DMSA), (4) Draximge DTPA [99mTc]Tc-diethylene-triamine pentaacetate ([99mTc]Tc-DTPA), and (5) tin colloid [99mTc]Tc-Tin colloid were reconstituted with 99mTc-pertechnetate in 0.9% saline at maximum activity and underwent QC assessments, including RCP and biological distribution tests.
99mTc Preparation
Radionuclide 99mTc was obtained from a 99Mo-99mTc generator at the Clinical Nuclear Medicine Department, Mubarak Al-Kabeer Hospital, Kuwait. The generator produces 99mTc from 99Mo via neutron activation of uranium targets, and efficient extraction requires careful monitoring of decay rates and generator performance.
99mTc-Kits Preparations
Each kit was reconstituted following the manufacturer’s instructions, including QC, RCP values, and storage conditions. Labeling efficiency was evaluated under varying temperatures, pH, reducing agents, oxygen and light exposure, and active component concentrations.
The Effect of Various Temperatures
Each kit was reconstituted as described and dispensed into 2-mL fractions, then stored under various conditions: recommended control temperature, refrigerated (2–8°C), room temperature (25°C), elevated (40–60°C), frozen (≤−20°C), 10–40°C, and freeze-thaw (−20°C to room temperature). Labeling efficiency was then determined.
The Effect after Exposure to LED and UV Light
Kits were prepared as described, dispensed into 2-mL fractions, and exposed for 10 min to LED (405 nm) or UV (365 nm) light. All other conditions remained unchanged, and labeling efficiency was measured.
The Effect after Exposure to pH
Although the ideal pH of parenteral radiopharmaceuticals is 7.4, values between 2 and 9 are acceptable due to blood’s buffering capacity. Each kit was prepared, dispensed into 2-mL fractions, and kept at room temperature. pH stability was tested by adding 0.5 mL of freshly prepared 0.5 m NaHCO3 after pertechnetate elution, and labeling efficiency was then determined.
The Effect of Reducing Agents and the Concentration of Active Components
Each kit was prepared, aliquoted into 2-mL fractions, and stored at room temperature. Samples were treated with either ascorbic acid (50 mg/mL) or stannous chloride (20 mg/mL) to assess in vitro stability, and labeling efficiency was subsequently measured. Ascorbic acid acted as an antioxidant and radioprotective agent to limit radiolysis, while stannous chloride ensured complete reduction of pertechnetate for optimal complexation. These conditions simulated oxidative and radiolytic stress to evaluate the impact of reducing agents on radiochemical stability.
The Effect after Exposure to Oxygen
Each kit was prepared, dispensed into 2-mL fractions at room temperature, and exposed to 20% oxygen for 5 min. Labeling efficiency was then assessed.
The Effect after Exposure to Dilution
Kits were prepared as usual, dispensed into 2-mL fractions, and stored at room temperature. Labeling efficiency was then assessed after halving the concentration using either saline or PBS.
The Effect after Exposure to Operator Changes
Kits were prepared per manufacturer instructions by a different operator, dispensed into 2-mL fractions at room temperature, and labeling efficiency was then measured.
The Effect after the Use of Different Solutions for Kits Preparation
Each kit was reconstituted per manufacturer instructions, but solvents were varied: physiological saline (154 mm), sucrose and fructose solution (0.1973 M), or PBS (137 mm NaCl, 2.7 mm KCl, 10 mm Na2HPO4, 1.8 mm KH2PO4). All other preparation parameters remained unchanged, and labeling efficiency was then calculated.
The Effect of Syringe Material on Radiopharmaceutical Preparations
Kits were reconstituted with 99mTc-pertechnetate in 0.9% saline and aliquoted into polyethylene, polypropylene (PP), and polyvinyl chloride syringes with 22- or 27-gauge needles. All other conditions remained unchanged, and labeling efficiency and syringe adsorption were assessed.
Statistical Analysis
Data are expressed as mean ± SD. Differences between groups were assessed using paired t-tests or ANOVA, with p < 0.05 considered significant. Analyses were performed using SPSS version 20.0 (IBM).
Results
The Effect of Various Temperatures
Table 1 summarizes the effect of temperature on five radiopharmaceuticals ([99ᵐTc]Tc-HMPAO, -MAA, -DMSA, -DTPA, and -Tin colloid) evaluated at <25°C, immediate use (0 h), 3 h, and 24 h. No significant changes in labeling efficiency or physical attributes were observed for MAA, DMSA, DTPA, or tin colloid. In contrast, [99ᵐTc]Tc-HMPAO showed a highly significant reduction (***p < 0.001) at both 3 h and 24 h compared to the reference standard.
Table 1.
The effect of different temperature ranges on the labeling efficiency of the prepared radiopharmaceuticals
| Radiopharmaceuticals | Control recommended temperature | Refrigerated conditions (2–8°C) | Room temperature (25°C) | Elevated temperature (40–60°C) | Frozen conditions (−20°C or lower) | From 10°C to 40°C | Freeze-thaw (−20°C to room temperature) |
|---|---|---|---|---|---|---|---|
| Ceretec (GE Healthcare), [99mTc]Tc-HMPAO | |||||||
| 0 h | 97%±0.1 | 97%±0.1 | 97%±0.1 | 96%±0.1 | 97%±0.1 | 97%±0.1 | 96%±0.1 |
| 3 h | 70%±0.1*** | 70%±0.1*** | 68%±0.1*** | 68%±0.1*** | 69%±0.1*** | 70%±0.1*** | 70%±0.1*** |
| 24 h | 0%±0.1*** | 0%±0.1*** | 0%±0.1*** | 0%±0.1*** | 0%±0.1*** | 0%±0.1*** | 0%±0.1*** |
| Pulmotech (GE Healthcare), [99mTc]Tc-MAA | |||||||
| 0 h | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 |
| 3 h | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 |
| 24 h | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 |
| Succimer (GE Healthcare), [99mTc]Tc-DMSA | |||||||
| 0 h | 100%±0.1 | 100%±0.1 | 100%±0.1 | 98.80%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 |
| 3 h | 100%±0.1 | 100%±0.1 | 100%±0.1 | 99%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 |
| 24 h | 100%±0.1 | 100%±0.1 | 100%±0.1 | 98%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 |
| DRAXIMAGE DTPA (GE Healthcare), [99mTc]Tc-DTPA | |||||||
| 0 h | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 |
| 3 h | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 |
| 24 h | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 | 100%±0.1 |
| Tin colloid (GE Healthcare), [99mTc]Tc-tin colloid | |||||||
| 0 h | 100%±0.1 | 100%±0.1 | 93.10%±0.1 | 98%±0.1 | 100%±0.1 | 94.40%±0.1 | 98.90%±0.1 |
| 3 h | 100%±0.1 | 100%±0.1 | 97.80%±0.1 | 98%±0.1 | 98%±0.1 | 96.40%±0.1 | 98%±0.1 |
| 24 h | 100%±0.1 | 100%±0.1 | 100%±0.1 | 98%±0.1 | 100%±0.1 | 98.00%±0.1 | 100%±0.1 |
A highly significant (***p < 0.001) compared to the reference standard.
The Effect after Exposure to LED and UV Light
Table 2 summarizes the labeling efficiency of radiopharmaceuticals following exposure to LED and UV light. LED light exposure did not result in significant changes (*p < 0.05) in labeling efficiency. In contrast, UV light exposure caused a marked reduction (***p < 0.001).
Table 2.
The labeling efficiency of radiopharmaceuticals after exposure to LED and UV light
| Changes in light type | ||
|---|---|---|
| radiopharmaceuticals | LED | UV |
| Kits | ||
| Ceretec | 100±0.1 | 82±0.1*** |
| MAA | 100±0.1 | 92±0.1*** |
| DMSA | 100±0.1 | 86±0.1*** |
| DTPA | 100±0.1 | 90±0.1*** |
| Tin colloid | 100±0.1 | 93±0.1*** |
A highly significant (***p < 0.001) compared to LED.
The Effect after Exposure to pH
Table 3 evaluates the effects of pH, reducing agents, oxygen, dilution, and operator variability on labeling efficiency. The radiopharmaceuticals generally retained labeling efficiencies above 95% under variations in these parameters. Most kits maintained stability within a pH range of 5.0 to 7.0. However, [99mTc]Tc-DMSA demonstrated slight sensitivity to pH shifts. Nevertheless, the overall labeling efficiency remained acceptable. From our results, ascorbic acid did not show any significant effect on the labeling efficiency of the studied kits (Table 3). In contrast, stannous chloride maintained good performance across most preparations; however, for tin colloid, the labeling efficiency decreased to 90%, representing the lowest value observed in Table 3.
Table 3.
The labeling efficiency of radiopharmaceuticals after exposure to pH, reducing agents, oxygen, dilution, and operator differences
| Changes | pH | Reducing agent | Oxygen | Dilution | Operator differences | |||
|---|---|---|---|---|---|---|---|---|
| stannous chloride | ascorbic acid | 20% | saline | PBS | 1 | 2 | ||
| Labeling efficiency, % | ||||||||
| Kits | ||||||||
| Ceretec | 100±0.1 | 100±0.1 | 100±0.1 | 100±0.1 | 100±0.1 | 97±0.1 | 97±0.1 | 100±0.1 |
| MAA | 97±0.1 | 100±0.1 | 100±0.1 | 100±0.1 | 100±0.1 | 96±0.1 | 98±0.1 | 97±0.1 |
| DMSA | 95±0.1 | 100±0.1 | 100±0.1 | 100±0.1 | 100±0.1 | 95±0.1 | 100±0.1 | 99±0.1 |
| DTPA | 98±0.1 | 100±0.1 | 100±0.1 | 100±0.1 | 100±0.1 | 97±0.1 | 100±0.1 | 100±0.1 |
| Tin colloid | 97±0.1 | 90±0.1 | 100±0.1 | 100±0.1 | 100±0.1 | 97±0.1 | 100±0.1 | 99±0.1 |
The Effect after Exposure to Oxygen
Exposure to 20% oxygen had no adverse effect on labeling efficiency, as all kits maintained 100% efficiency (Table 3). Similarly, dilution with saline preserved 100% efficiency across all preparations. In contrast, the use of PBS led to a slight reduction in labeling efficiency: [99ᵐTc]Tc-DMSA decreased to 95%, [99ᵐTc]Tc-MAA and [99ᵐTc]Tc-DTPA to 96–97%, and [99ᵐTc]Tc-HMPAO to 97%. These changes, however, were not statistically significant.
The Effect after Exposure to Dilution
In our study, diluting the preparation to half or double the recommended volume, whether in saline or PBS, did not significantly affect labeling efficiency.
The Effect after Exposure to Operator Changes
Minimal operator variation was observed. Operator 1 showed slightly lower labeling efficiency for [99ᵐTc]Tc-MAA and [99ᵐTc]Tc-DMSA (96–98%) compared to operator 2 (99–100%).
The Effect after the Use of Different Solutions for Kits Preparation
Table 4 shows labeling efficiencies of kits prepared with saline, sucrose, fructose, or PBS. All excipients maintained product integrity, and no significant differences were observed (ANOVA, p > 0.05), with high labeling efficiencies in all cases.
Table 4.
The labeling efficiency of radiopharmaceuticals after the use of physiological saline (control), sucrose, and fructose solution, and PBS in kits preparation
| Changes | Solvents | ||||
|---|---|---|---|---|---|
| physiological saline | sucrose solution | fructose solution | PBS | ||
| Kits | |||||
| Ceretec | 100±0.1 | 98±0.1 | 98±0.1 | 97±0.1 | |
| MAA | 100±0.1 | 97±0.1 | 98±0.1 | 99±0.1 | |
| DMSA | 100±0.1 | 99±0.1 | 97±0.1 | 98±0.1 | |
| DTPA | 100±0.1 | 98±0.1 | 98±0.1 | 98±0.1 | |
| Tin colloid | 100±0.1 | 98±0.1 | 98±0.1 | 100±0.1 | |
Effect of Syringe Material and Needle Gauge
Table 5 and Figure 1 demonstrate radiopharmaceutical adsorption trends relative to syringe material (polyethylene, PP, and polyvinyl chloride) and needle (22 and 27) gauge. Among syringe types, PP exhibited the highest adsorption, particularly for [99mTc]Tc-HMPAO (mean adsorption of 18%). The overall adsorption order was: HMPAO >tin colloid >DMSA >DTPA >MAA. Despite these adsorption differences, no significant effect on labeling efficiency was observed (ANOVA, p > 0.05).
Table 5.
The labeling efficiency of radiopharmaceuticals after the use of different syringes’ materials and needle’s gauges
| Changes | PE | PP | PVC | |||
|---|---|---|---|---|---|---|
| 22 gauge | 27 gauge | 22 gauge | 27 gauge | 22 gauge | 27 gauge | |
| Kits | ||||||
| Ceretec | 99±0.02 | 99±0.02 | 97±0.01 | 97±0.01 | 99±0.01 | 99±0.01 |
| MAA | 98±0.01 | 98±0.01 | 98±0.01 | 98±0.01 | 98±0.02 | 98±0.02 |
| DMSA | 98±0.01 | 98±0.01 | 99±0.02 | 99±0.02 | 97±0.01 | 97±0.01 |
| DTPA | 98±0.01 | 98±0.01 | 98±0.01 | 98±0.01 | 98±0.01 | 98±0.01 |
| Tin colloid | 97±0.01 | 97±0.01 | 98±0.01 | 98±0.01 | 97±0.01 | 97±0.01 |
PE, polypropylene; PVC, polyvinyl chloride.
Fig. 1.
Adsorption of tested 99ᵐTc-radiopharmaceuticals onto different syringe materials (polypropylene [PP], polyethylene [PE], and polyvinyl chloride [PVC]) and needle gauges (22 and 27). Data are presented as mean adsorption percentages. Solid columns represent PP syringes, open columns represent PE syringes, and hatched columns represent PVC syringes.
Discussion
Understanding factors affecting labeling efficiency and integrating new technologies can improve diagnostic accuracy, therapeutic outcomes, and safety. In this study, [99ᵐTc]Tc-HMPAO showed notable thermal instability, consistent with its reported short shelf life and sensitivity to temperature [1, 5]. Our findings align with prior research on the temperature sensitivity of [99ᵐTc]Tc-HMPAO and -DMSA, where thermal degradation led to altered biodistribution and reduced RCP [2–4]. Similar observations have been reported in studies investigating storage temperature changes [7]. In contrast, other tested radiopharmaceuticals such as [99ᵐTc]Tc-MAA, -DTPA, and -tin colloid retained stable labeling efficiencies despite exposure to elevated temperatures, suggesting their robustness against thermal stress.
The impact of light, particularly UV irradiation, was evident across all studied radiopharmaceuticals. Photodegradation mechanisms, including bond cleavage and technetium reoxidation to the +7 state, compromised the formation of stable coordination complexes and reduced labeling yields [8, 9]. This translates to diminished biological targeting efficiency and increased nonspecific uptake, especially in the thyroid and stomach. While UV has been reported to enhance radiolabeling in monoclonal antibodies through photoactivation [10], our results reinforce its destructive effect on conventional radiopharmaceuticals [10, 11]. Importantly, exposure to 365 nm UV photons (3.40 eV) caused more pronounced degradation than 405 nm LED photons (3.06 eV), as the higher energy was sufficient to cleave technetium-ligand bonds, particularly those involving nitrogen or sulfur donors. This explains the sharper decline in labeling efficiency under UV compared to LED illumination.
Most kits maintained labeling efficiency within the physiological pH range of 5.0–7.0 [12, 13]. Neither [99ᵐTc]Tc-HMPAO nor [99ᵐTc]Tc-MAA was significantly influenced by pH variation, consistent with earlier studies [5, 14]. However, [99ᵐTc]Tc-DMSA showed slight sensitivity, confirming that pH can act as a determinant of radiopharmaceutical effectiveness [15, 16]. Although some reductions were observed, labeling efficiencies remained within acceptable limits. These findings highlight that pH optimization remains crucial in formulations used for SPECT and PET imaging, as it can directly influence image quality [17, 18].
Reducing agents are indispensable for maintaining RCP by preventing technetium reoxidation. Ascorbic acid, a commonly used additive, effectively neutralizes free radicals and minimizes radiolysis, yielding consistently high labeling efficiencies [19, 20]. Our results indicated that SnCl2, although widely used in cold kits, had no significant effect on labeling efficiency, in agreement with earlier reports [21, 22]. However, auto-radiation-induced decomposition and oxygen exposure can promote pertechnetate formation [23]. Here, ascorbic acid demonstrated superior performance compared to SnCl2, particularly for tin colloid, suggesting its utility as a universal stabilizer. Exposure to 20% oxygen and the choice of saline as diluent did not compromise stability. However, use of PBS slightly reduced labeling efficiency in some kits, likely due to phosphate ion interference or ionic strength differences, though these effects were not statistically significant.
Minimal variation between operators confirmed the high reproducibility of kit preparations, reflecting the value of standardized protocols. Future integration of multivariate analysis and machine learning into QC offers promise for predictive monitoring of stability and performance. Automated synthesizers and real-time monitoring systems are poised to improve reproducibility, reduce human error, and ensure regulatory compliance while lowering costs [24, 25].
Adsorption of radiopharmaceuticals to syringe surfaces remained below clinically significant levels, but syringe material was shown to influence preparation outcomes. Lipophilic tracers such as [99ᵐTc]Tc-HMPAO were particularly susceptible, supporting earlier findings on syringe compatibility [26, 27]. Careful material selection remains essential to avoid RCP loss during preparation and administration.
Labeling efficiency of [99ᵐTc]Tc-HMPAO assessed by TLC and RP-HPLC produced comparable results. While TLC effectively distinguished parent and degraded forms, RP-HPLC provided faster, more sensitive, and precise quantification, making it preferable for quality assurance in high-throughput settings.
Particle size plays a crucial role in the biodistribution and stability of [99ᵐTc]Tc-tin colloid. Literature reports indicate freshly prepared colloids exhibit particle sizes of 200–500 nm, associated with labeling efficiencies above 95% and predictable biodistribution [28, 29]. Aggregation beyond 700 nm can alter biodistribution, sometimes leading to unexpected lung uptake. While our study did not directly measure particle size, we acknowledge the importance of dynamic light scattering and electron microscopy as complementary methods. Future studies incorporating particle size analysis will provide a more comprehensive evaluation of colloid stability.
General Findings and Implications
[99ᵐTc]Tc-HMPAO was the most sensitive compound, while other kits remained robust (labeling efficiency ≥95%), supporting potential shelf-life extension under controlled conditions. Advances in automation, AI-assisted QC, and nanotechnology could further improve reproducibility, efficiency, and personalized radiopharmaceutical preparation [24, 25].
Conclusion
This study underscores the need for optimized handling and storage to maintain radiopharmaceutical stability. Except for HMPAO, most compounds were robust, suggesting shelf-life extension may be possible. Automation, AI-assisted synthesis, and particle size monitoring (e.g., dynamic light scattering) can further improve consistency, stability, and imaging quality.
Acknowledgments
The authors would like to thank the staff and the facilities provided from the Department of Nuclear Medicine, Mubarak Al-Kabeer Hospital, Ministry of Heath, Jabriya, Hawalli Health Area, Kuwait.
Statement of Ethics
This study protocol was reviewed and approved by the Permanent Committee for Coordination of Medical and Health Research – Ministry of Health – Kuwait, approval no. (reference no.: 2789/2024).
Conflict of Interest Statement
The authors have no conflicts of interest to declare.
Funding Sources
This study was not supported or funded by any sponsor or funder.
Author Contributions
Fatma J. Al-Saeedi conceived and designed the concept, idea, and the experiments. Fatma J. Al-Saeedi wrote the draft and edited the final manuscript. Fatma J. Al-Saeedi, Zainab S. Al-Qallaf, and Shatha N. Khalaf analyzed the data. Fatma J. Al-Saeedi, Zainab S. Al-Qallaf, and Shatha N. Khalaf performed the experiments. All authors contributed reagents/materials/analysis tools, revised the manuscript, and read and approved the final manuscript.
Funding Statement
This study was not supported or funded by any sponsor or funder.
Data Availability Statement
All data generated or analyzed during this study are included in this published article and its online supplementary material files. Plus, the datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
All data generated or analyzed during this study are included in this published article and its online supplementary material files. Plus, the datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.