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DNA nanohydrogel loaded Liposomal formulations for high loading efficiency of antimicrobial drugs against intracellular bacterial and topical biofilm infections

Periodic Reporting for period 1 - NANOZID (DNA nanohydrogel loaded Liposomal formulations for high loading efficiency of antimicrobial drugs against intracellular bacterial and topical biofilm infections)

Reporting period: 2019-05-15 to 2021-05-14

The delivery of antimicrobial therapies against persisting biofilm and intracellular infections is challenged by restricted drug penetration and low drug retention. To enhance therapeutic drug concentrations, the use of higher doses of antibiotics risks the development of drug resistant infections and severe drug toxicity. While drug delivery platforms such as liposomes, can enhance the intracellular/biofilm transport of antimicrobial drugs, low drug loading and untimely release of the cargo challenge their potency.

Advanced carriers fabricated from nucleic acids are biocompatible nanomaterials which show high loading capacity for antimicrobial drugs. Nevertheless, these carriers are susceptible to nuclease degradation which can compromise cargo delivery. To safeguard antimicrobial systems, the development of a hybrid system comprising nucleic acid nanoparticles coated with a liposome can improve drug loading against persisting infections.

The project delivered its primary research objectives of developing a topical hybrid formulation with ideal physicochemical property for the delivery of vancomycin. The secondary objective to examine the distribution (within immune cells and biofilms) and impact on drug release profile was also achieved. Finally, the compatibility and performance of the hybrid formulation was delivered as the third objective. Training objectives aimed to enhance the employability of the early career researcher (ER) by identifying international collaborators and securing a start-up grant were also achieved. The ER secured a funded start-up grant from Tromsø Research Foundation (TFS start-up) which was granted in 2020 and will begin in 2022 after completion of the current grant.
An adaptable biohybrid formulation comprising nucleic acid nanoparticles enveloped within liposomes was developed. Feasibility of the system for the delivery of vancomycin was demonstrated against intracellular infections and biofilm infections by varying the lipid composition of the formulation. Using a neutrally charge lipid shell in the first study, higher drug loading was demonstrated in comparison to the liposome formulation. The binding affinity of vancomycin to the nucleic acid nanoparticles was proven and depended on the concentration of the drug. Loading of vancomycin in the lipid envelop extends up to 1.28 mg/mL and concentrations higher than this were detrimental to the size of the hybrid formulation and the encapsulation of the nucleic acid nanoparticles. The hybrid significantly sustained the release of vancomycin and improved the activity of vancomycin against intracellular infections compared to the free drug. Its potent anti-inflammatory and anti-oxidant activity was proven. Surface modification of the hybrid via the incorporation of a pH responsive lipid and mannose functionalized lipid was explored. The resulting responsive hybrid (termed zwitterionic nanoparticle) was tailored to the biofilm microenvironment. Modulation of the molar percentage of the anionic lipid impacted the sensitivity of the hybrid in the biofilm microenvironment. Consequently, the pH adaptable feature enhanced bacteria binding and biofilm penetration. Due to the controlled release of vancomycin, the system penetrated the biofilm and enhanced the biocompatibility to skin cells. There is immense benefit of the platform against other human disease which extend beyond the primary objectives of the project.

The fellow was nominated to compete for a start-up-grant in 2020. Within the scope of the Marie-Curie Fellowship, the fellow supervised three (3) master students. Four (4) collaborators were identified within the host institution who supported the research activities of the project. The fellow was named the ‘Young Researcher of the Year’ (https://uit.no/nyheter/artikkel/kortnytt?p_document_id=733781) at UiT The Arctic University of Norway in 2021 and was selected into the talent program, AURORA OUTSTANDING at UiT for mentoring young research leaders. Extensive knowledge/ skills on lipid-based formulations and biofilm models were developed and teaching opportunities were provided.

Research results were disseminated at scientific meetings/seminars. Two (2) original research articles and one (1) review paper was published during the course of the fellowship. The fellow joined a group of researchers at UiT in ‘Forsknings dagene’ (Research Days) to educate young people on antimicrobial resistance. An animated video is in its final stages of preparation and is aimed at simplifying the fellow's research for public dissemination.
Initial experiments exploring the use of neutral lipids achieved higher entrapment efficiency of vancomycin in the hybrid than the liposomal control system. Such platforms offer new approaches to develop high loading nanomedicines for antibiotics which are beyond the current state-of-art. Evaluations of this system against intracellular infections demonstrated its potency and multifunctional anti-inflammatory and anti-oxidant activity. To extend the applications into biofilm infections, modulation of the lipid compositions was successful. This created a system showing unique binding affinity and responsiveness to the biofilm microenvironment. Exploiting this approach provides an immense advantage over current pharmaceuticals and is can be exploited by the pharmaceutical industry and the research community in addressing antimicrobial resistance. Efforts to extend the application of these systems by incorporating other biomacromolecules will be explored in the future. Overall three papers were published under this project.
TEM images of the lipid coated antimicrobial nanoparticles and uptake in macrophages