Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

ABSTRACTInjections with a hypodermic needle and syringe (HNS) are the current standard of care globally, but the use of needles is not without limitation. While a plethora of needle-free injection devices exist, vaccine reformulation is costly and presents a barrier to their widespread clinical application. To provide a simple, needle-free, and broad-spectrum protein antigen delivery platform, we developed novel potassium-doped hydroxyapatite (K-Hap) microparticles with improved protein loading capabilities that can provide sustained local antigen presentation and release. K-Hap showed increased protein adsorption over regular hydroxyapatite (P< 0.001), good structural retention of the model antigen (CRM197) with 1% decrease in α-helix content and no change in β-sheet content upon adsorption, and sustained releasein vitro. Needle-free intradermal powder inoculation with K-Hap–CRM197induced significantly higher IgG1 geometric mean titers (GMTs) than IgG2a GMTs in a BALB/c mouse model (P< 0.001) and induced IgG titer levels that were not different from the current clinical standard (P> 0.05), namely, alum-adsorbed CRM197by intramuscular (i.m.) delivery. The presented results suggest that K-Hap microparticles may be used as a novel needle-free delivery vehicle for some protein antigens.

Original publication




Journal article


Clinical and Vaccine Immunology


American Society for Microbiology

Publication Date





586 - 592