Efficacy & functionality of antibiotic delivery through DNA based nanoparticles

Abstract

Purpose: Last year we presented a novel class of DNA nanoparticles (NPs) and first experiments of neomycin & kanamycin conjugated DNA-NPs showed a prolonged adherence of the AB to ex-vivo human and in-vivo rat corneas. Additionally, bacterial growth tests using E.coli showed a retained activity of the ABs in medium.

Methods: In this study kanamycin & neomycin were conjugated to DNA-based NPs via aptamers. Loaded NPs and the ABs itself were dropped on ex-vivo pig corneas, then washed after 5 min and transferred to petrifilms. Then, E.coli colonies were applied onto the corneas, incubated at 37°C for 48h and the amount of colonies were counted. Furthermore, kanamycin & neomycin loaded NP, as well as the AB alone, were dropped on rat eyes. After different incubation periods they eyes were homogenised and evaluated by liquid chromatography-mass spectrometry (LC-MS). Additional in-vivo and in-vitro toxicity-tests were performed to ensure safety of the system.

Results: For neomycin the AB is found not to be active when it is complexed to the NP. However, upon presence of RNAse, activity is restored. As with the in-vitro MIC-Test, the functionality of kanamycin is well conserved when loaded to the NP. Both AB alone and the loaded AB-NPs were able to significantly decrease the amount of colonies compared to the vehicle control treated corneas. Even more, after an incubation time and subsequent washing of 5 min the NP delivered kanamycin is significantly better than the pure AB. This effect lasts until 60 min after incubation after which the NP delivered kanamycin also lost its function. The functionality data is consistent with the adhesion data obtained as pure kanamycin was not detectable after 5 min whereas the NP delivered kanamycin could not be detected anymore after 60 min. Finally, no toxicity was observed with the AB loaded NP-carrier.

Conclusions: We present, for the first time, the functionality of our DNA-based NP carrier system on tissue. This is an important step to prove that drugs bound to the NP are still functional or functionality can be restored. Since we are able to bind the drugs to the NP using different methods, we not only created a better adhesion but also a drug release system that can be used to tailor the release of the drug, resulting in an improved pharmacokinetic uptake of the drug. Further research needs to be performed in infected animals to further explore the potential of this carrier system.