LAUSR

One of the main challenges in oral disease is prevention of bacterial infections considering antibiotic resistance as a result of frequent use of conventional antibiotics. A natural alternative to these chemical antibiotics is antimicrobial peptide (AMP). LL37, a helical and amphipathic peptide with 37 amino acid residues, is the only cathelicidin-derived form of AMPs in humans that has a broad spectrum of antimicrobial activity (Majewski et al. in Cent Eur J immunol 43(4):453–457, https://doi.org/10.5114/ceji.2018.81355 , 2018). In this study a bi-functional fusion peptide was designed, which consisted of LL-37 peptide linked to a hydroxyapatite (HA) binding peptide through a GGGGS linker. The fusion peptide antimicrobial activity was assessed against both gram-positive and gram-negative bacteria by the microtiter plate method and minimum inhibitory concentrations of 250 µg/ml and 125 µg/ml were obtained for Streptococcus mutans and Escherichia coli , respectively. The binding affinity of the HABP-LL37 fusion peptide to HA-surfaces was confirmed by the peptide release test using the spectrometer method. The HABP-LL37 fusion peptide immobilization on HA surfaces was done using a simple soaking technique. It was shown that 100 mg of the HA polymer disk could load up to 278 μg (55.6%) of LL37-HABP. Evaluation of the cytotoxic properties of the designed fusion peptide before and after immobilization on HA polymer disks against C2C12 cells showed that immobilization resulted in the reduction of HABP-LL37 cytotoxicity. The use of this bi-functional peptide with HA-based biomaterial can result in the development of novel and safe antimicrobial bone substitutes to manage and reduce the complications of device infection.