Sodium Hyaluronate/Chitosan Composite Microneedles as a Single-Dose Intradermal Immunization System

Area of Science:

• Biomaterials Science
• Immunology
• Vaccine Delivery Systems

Background:

• Vaccine efficacy is often limited by the need for repeated inoculations.
• Developing effective single-dose vaccination strategies remains a significant challenge.
• Intradermal delivery offers potential for enhanced immunogenicity.

Purpose of the Study:

• To develop and evaluate a composite microneedle (MN) system for single-dose vaccination.
• To investigate the biphasic antigen release profile of a sodium hyaluronate (HA) and chitosan MN.
• To assess the immunogenicity of the HA/chitosan MN as an alternative to conventional prime-boost regimens.

Main Methods:

• Fabrication of a composite MN with a dissolvable HA tip and a biodegradable chitosan base.
• Encapsulation of ovalbumin (OVA) antigen within the MN system.
• Intradermal administration of the HA/chitosan MN in a rat model.
• Evaluation of immune responses, including antibody titers and T helper cell responses, compared to subcutaneous vaccination.

Main Results:

• The HA/chitosan MN exhibited biphasic antigen release: rapid from the HA tip and sustained from the chitosan base for 4 weeks.
• A single immunization with OVA-loaded HA/chitosan MN stimulated both T helper type 1 (Th1) and Th2 immune responses.
• The single-dose MN vaccination induced significantly higher and more durable antibody responses than two-dose or double-dose subcutaneous vaccinations.

Conclusions:

• The HA/chitosan MN system effectively delivers antigens for both rapid priming and sustained boosting of the immune system.
• This composite MN formulation demonstrates strong adjuvanticity, augmenting antigen immunogenicity.
• The developed MN has the potential to serve as an effective single-dose vaccine, replacing conventional prime-boost strategies.