Introduction to core-shell fibers in drug delivery
Core-shell fibers have emerged as a versatile platform for controlled drug delivery. By stacking distinct materials into a core and a surrounding shell, researchers can tailor diffusion, stability, and interaction with biological environments. This design is particularly relevant for delivering antiretroviral therapies (ART) and other therapeutics where precise release kinetics, mechanical integrity, and biocompatibility are crucial for efficacy and patient adherence.
Key properties influenced by core-shell architecture
The core-shell structure can modulate several critical properties:
- Drug release kinetics: The shell can act as a barrier or regulator, delaying release, smoothing initial burst effects, and enabling zero- or near-zero-order release profiles depending on shell thickness, permeability, and the physicochemical mismatch between core and shell materials.
- Mechanical strength and flexibility: The shell provides protection to the drug-loaded core while maintaining flexibility of the fiber. This balance is essential for implantable or wearable devices that experience mechanical stress during handling or use.
- Stability and protection of labile drugs: A protective shell can shield sensitive therapeutics from environmental factors (e.g., moisture, enzymes), enhancing shelf-life and in vivo stability.
- Biocompatibility and interaction with tissue: Material choices for core and shell influence tissue response, inflammation, and clearance. Biocompatible shell materials can mitigate adverse reactions while permitting targeted diffusion to the desired site.
- Degradation and clearance: Some core-shell systems are designed to degrade predictably, releasing the drug as the shell erodes or remains intact for longer-term therapy depending on the clinical need.
<h2 Material considerations and design strategies
Choosing compatible core and shell materials is essential. Common combinations include a hydrophilic shell for rapid diffusion paired with a hydrophobic drug-loaded core, or a biodegradable polymer shell surrounding a ceramic or polymeric core for sustained release. Design strategies include:
- Material compatibility: Ensure chemical compatibility to prevent premature drug inactivation or phase separation between core and shell.
- Shell thickness and porosity: Thinner shells may yield faster release, while thicker or less porous shells slow diffusion, enabling tunable pharmacokinetics.
- Drug localization: Some systems confine the drug to the core, while others distribute it across the interface for a combined diffusion mechanism.
- Fabrication method: Techniques such as coaxial electrospinning, self-assembly, or phase separation influence layer integrity and scalability.
<h2 Applications in HIV treatment and beyond
In the context of HIV treatment, core-shell fibers can be engineered for sustained antiretroviral drug release, potentially improving adherence by reducing dosing frequency. Beyond HIV, this architecture supports oncology, vaccination, pain management, and chronic disease therapies where controlled, localized, or long-term drug delivery offers clinical benefits.
<h2 Evaluation and translation to practice
Preclinical evaluation should cover release profiling under physiological conditions, mechanical testing to ensure device integrity, biocompatibility assays, and in vivo pharmacokinetics to verify that the designed release matches therapeutic needs. Regulatory considerations include material safety, reproducibility of the fabrication process, and robust quality control for scalability.
Conclusion
The core-shell fiber composition provides a powerful toolkit for engineering drug delivery systems with tailored release, improved stability, and biocompatibility. As materials science converges with pharmacology, these sophisticated fibers hold promise for advancing ART and a wide range of medicines, enabling more effective and patient-friendly therapies.
