Construction of injectable, pH sensitive, antibacterial, mineralized amino acid yolk-shell microspheres for potential minimally invasive treatment of bone infection

Abstract

Introduction: Treatment of infection within bone is difficult, and conventional surgical treatment brings intense pain to the patients physically and mentally. There is an urgent need to develop injectable nano-and/or micro-medicine for minimally invasive treatment of osteomyelitis. Methods: In this paper, amino acid (L-lysine [Lys]) was mineralized into yolk-shell structured CaCO3 microspheres (MSs). The morphologies of the obtained MSs were investigated by scanning electron microscopy and transmission electron microscopy. The composition of CaCO3 MSs was identified by using Fourier transform infrared spectroscopy. The as-prepared CaCO3 MSs were examined with power X-ray diffraction analysis to obtain the crystallographic structure of the MSs. Results: The as prepared Lys encapsulated CaCO3 MSs (Lys@CaCO3 MSs) were used as micro-drug to improve acidic environment of osteomyelitis caused by bacterial infection and promote osteoblast proliferation under oxidative stress. These pH responsive Lys@CaCO3 MSs have a drug loading efficiency of 89.8 wt % and drug loading content (DLC) of 22.3 wt %. Conclusion: Our results demonstrated that Lys@CaCO3 MSs can effectively kill Staphylococcus aureus and promote proliferation and differentiation of osteoblasts under stimulation of H2 O2 at pH = 5.5.