Synthesis, modification, and chlorhexidine loading of polymer modified-HM-HAP particles: In vivo antibacterial...

Hydroxyapatite (HAP) is commonly known as an excellent biocompatible and a potential solution to be used in drug delivery applications. This paper examines the synthesis, modification, and loading of chlorhexidine (CHD) drug into hollow mesoporous hydroxyapatite (HM-HAP) particles to increase the antibacterial efficacy for oral infections. HM-HAP particles were synthesized and modified with different weight polymers that is, polyethylene glycol (PEG (1000, 2000, 4.6k)) and polyethyleneimine (PEI (1200, 1800)), to improve the surface properties and drug loading ability. Chlorhexidine was effectively loaded onto both unmodified and polymer-modified HM-HAP samples, achieving loading efficiencies up to 81.67% for HM-HAP and 77.85% for PEG-1000/HM-HAP verified by UV-vis analysis. The CHD-loaded samples were then eventually incorporated into sodium polyacrylate (PAAS) gels to improve their sticking properties, hence enabling effective adherence to the treatment site and enhancing the local antibacterial effect. The antibacterial activity of both CHD-loaded polymer-modified HM-HAP samples and CHD-loaded polymer-modified HM-HAP gel samples was evaluated both in vitro and in vivo. In in vitro tests, PEI-1200/HM-HAP and PEG-1000/HM-HAP gels exhibited the largest inhibition zones of ∼1.6 cm against Escherichia coli and ∼1.5 cm against Staphylococcus aureus, respectively. In vivo study evaluated the antibacterial efficiency of the CHD-loaded polymer modified HM-HAP gel samples by isolating oral bacteria from mouse teeth, with Gel-PEI-1200/HM-HAP@CHD and Gel-PEG-1000/HM-HAP@CHD samples demonstrating superior antibacterial performance. These findings suggest that CHD-loaded polymer-modified HM-HAP is a promising therapeutic drug delivery system for oral health applications, with PEI-modified HM-HAP exhibiting the slight quickest release and PEG-modified HM-HAP showing sustained activity.