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Electrospinning is a technique that creates nanofibers by applying high-voltage electrostatic forces to a polymer solution within a needle-shaped nozzle. The physical properties of the nanofibers can be tuned by varying parameters such as the polymer, solvent, and solution flow rate, as well as by applying voltage. The characteristic of electrospinning is that the solvent evaporates quickly due to the high surface area of the nanofibers, allowing it to be manufactured at room temperature. This ability makes it promising for applications in tissue engineering, regenerative medicine, preparation of wound dressings, and synthesis of drug formulations. In general, electrospinning involves applying high voltages of 10 to 40 kilovolts to a solution, but the current is very low in the microampere range; therefore, energy consumption is also low. The process is carried out at room temperature and is suitable for unstable biomolecules, which is advantageous for nucleic acid-based drugs despite challenges in productivity.
The main point of this paper
Electrospinning technology:
Electrospinning is a commonly used method for preparing nanofibers, which can provide large specific surface area and high porosity, which is particularly important for drug delivery systems. In your study, siRNA-loaded nanofibers were prepared by electrospinning, which can improve the encapsulation efficiency and controlled release of drugs.
Application of polyvinyl alcohol (PVA):
PVA, as a water-soluble polymer, is widely used in drug formulations. The physical properties of PVA, such as water solubility and hydrolysis degree, make it a strong candidate for controlled release of nucleic acid drugs. PVA was used as the base matrix in your study, which is a wise choice because it can become insoluble through cross-linking, which is very useful for the preparation of applications such as wound dressings.
Selection of PVA grade:
Different PVA grades (distinguished by polymerization and saponification degree) have different effects on siRNA inhibition of luciferase activity. Therefore, a comprehensive analysis of the encapsulation efficiency of nucleic acid drugs and their cellular uptake efficiency in relation to different grades of PVA is necessary to optimally utilize PVA-based nanofibers as a universal platform for delivering nucleic acid drug formulations.
Integration of cationic lipids or alternative transfection agents:
Integration of cationic lipids or alternative transfection agents is essential for nucleic acid drug formulation. The cationic lipid DOTAP electrostatically interacts with negatively charged cell membranes, facilitating its adsorption and internalization by cells via endocytosis, which is essential for the function of the drug
Application of A549-Luc cells:
Your study used A549-Luc cells, a cell line derived from human non-small cell lung cancer with stable luciferase expression. This cell line is an ideal model for evaluating the intracellular distribution of siRNA and the effect of RNA interference (RNAi)
Advantages of PVA nanofibers for drug delivery:
PVA nanofibers have been shown to have advantages in drug delivery applications, especially in terms of controlled release and biocompatibility
Nanofiber properties:
The prepared PVA nanofibers have a diameter of 300-400 nm, siRNA remains intact during the preparation process, and the DOTAP/siRNA complex is uniformly dispersed in the nanofibers.
RNA interference (RNAi) activity:
The RNAi activity of DOTAP/siRNA complexes on A549-Luc cells (human non-small cell lung cancer cells, stably expressing luciferase) was evaluated by incorporating them into PVA nanofibers, and stable inhibition of luciferase expression was observed.
Effect of the preparation process:
The study showed that adding DOTAP or siRNA alone to the PVA solution can produce RNAi effects even without forming a DOTAP/siRNA complex.
Cell internalization and PVA residues:
The DOTAP/siRNA complexes released from PVA nanofibers are internalized by cells, and some PVA residues remain on the cell surface.
Effect of PVA properties on performance:
The degree of hydrolysis and polymerization of polyvinyl alcohol have a significant effect on the performance of nanofibers. PVA with a low degree of hydrolysis can significantly enhance the RNAi effect, and the luciferase expression inhibition rate can reach 91.5±0.7%.
This study aimed to develop a nucleic acid drug delivery system using electrospun PVA nanofibers by encapsulating DOTAP/siRNA complexes within PVA nanofibers and to elucidate the properties of siRNA-encapsulated nanofibers, including their RNAi activity. The results showed that electrospinning could effectively encapsulate DOTAP/siRNA complexes within PVA nanofibers. Stable inhibition of luciferase expression was observed even when each component was directly added to the PVA solution, bypassing the DOTAP/siRNA complex preparation process. In addition, the surface of the DOTAP/siRNA complex released from the PVA nanofibers contained PVA residues, suggesting that the properties of PVA may affect the interaction between the complex and cells. Therefore, the degree of hydrolysis and polymerization, or the grade of PVA, affected the inhibition of luciferase expression, and higher RNAi activity was observed with PVA of low hydrolysis degree. Although modified PVA carrying charges is not currently approved as a drug excipient, the strong inhibition of luciferase expression suggests that mixing charged polymers with PVA may produce more effective nanofibers for the delivery of nucleic acid drugs into cells.
