Periodic Reporting for period 1 - AIMed (Antimicrobial Integrated Methodologies for orthopaedic applications)
Periodo di rendicontazione: 2020-01-01 al 2021-12-31
The increase in infections by antibiotic-resistant bacteria has become of great concern in hospitals after surgical orthopaedic procedures. There have been recent developments that focus on non-antibiotic anti-biofilm agents to help disrupt biofilm formation on orthopaedic surfaces. These include surface modifications of orthopaedic implants and the use of novel material alloys or nano-patterning of already existing materials. Considering these developments, there is an urgent need for interdisciplinary trained researchers with knowledge of antimicrobial methodologies. Such a cadre of skilful researchers will lead to faster development and adoption of antibiotic-free methodologies and thus an effective alternative to antibiotic treatment of orthopaedic infections. Recognising a lack of coordinated activities in this area of research, AIMed will not only train 15 early-stage researchers (ESRs) but also develop novel and effective antimicrobial methodologies for preventing orthopaedic infections. The main aim is to develop innovative antimicrobial metallic, ceramic and polymeric surfaces with antimicrobial peptides inspired by the antimicrobial core of human defensins, as well as using surface engineering. AIMed is timely, coinciding as it does with global initiatives such as the WAAAR, TATFAR, GARP and CARB-X, all of which seek solutions to bacterial antibiotic-resistant infections. AIMed's research objectives are the following:
1. The creation of new antimicrobial metallic, polymeric and ceramic surfaces by the use of chemical and physical surface modification to allow functionalisation of surfaces with antimicrobial peptides, doping with metal ion antibacterial agents and patterning of surfaces at micro and nanoscale to study physical mechanisms underlying antimicrobial action;
2. The creation of novel antimicrobial peptides mimicking the antimicrobial core of human defensins to realize antibacterial structures, and the use of molecular biology techniques to identify the best possible sequences;
3. The development of novel characterization procedures and workflows for the efficient determination of antimicrobial behaviour and the biocompatibility of the new materials;
4. The development of new standards for antimicrobial materials and procedures;
5. To disseminate scientific and technological knowledge to stakeholders.
The ESRs will undertake a multi-disciplinary and intersectoral research programme designed to develop innovative antimicrobial materials and devices based on physical and chemical surface functionalization as well as specific characterization workflows of anti-microbial properties. AIMed will lead to the advancement of knowledge in the aforementioned fields related to antimicrobial materials and device concepts and their characterization and optimization with respect to efficiency and scalability/manufacturability, thus opening scientific horizons for new applications in the area of infection prevention and treatment.
1. The creation of new antimicrobial metallic, polymeric and ceramic surfaces by the use of chemical and physical surface modification to allow functionalisation of surfaces with antimicrobial peptides, doping with metal ion antibacterial agents and patterning of surfaces at micro and nanoscale to study physical mechanisms underlying antimicrobial action;
2. The creation of novel antimicrobial peptides mimicking the antimicrobial core of human defensins to realize antibacterial structures, and the use of molecular biology techniques to identify the best possible sequences;
3. The development of novel characterization procedures and workflows for the efficient determination of antimicrobial behaviour and the biocompatibility of the new materials;
4. The development of new standards for antimicrobial materials and procedures;
5. To disseminate scientific and technological knowledge to stakeholders.
The ESRs will undertake a multi-disciplinary and intersectoral research programme designed to develop innovative antimicrobial materials and devices based on physical and chemical surface functionalization as well as specific characterization workflows of anti-microbial properties. AIMed will lead to the advancement of knowledge in the aforementioned fields related to antimicrobial materials and device concepts and their characterization and optimization with respect to efficiency and scalability/manufacturability, thus opening scientific horizons for new applications in the area of infection prevention and treatment.
In the period from the 1st of January 2020 to the 31st of December 2021, eight antimicrobial peptides were developed by the team at UoB. Mod1 and Mod8 peptides were selected as the most effective antimicrobials. UPHF established a molecular biology synthesis route where the DNA of Mod1 was fused with a collagen-like protein. An emphasis on the production of peptides to support peptides supply to the network was given. At UoB, the chemical and physical modification of metal surfaces progressed significantly with optimisation experiments in progress. GelMA and alginate-based bioinks were developed at UPS. The systems seem diverse and can interact with both metal ions and antimicrobial peptides. Antimicrobial studies are currently in progress. UNITS developed a human elastin-like polypeptide (HELP) construct with antimicrobial domains consisting of a tandem of the modified HBDmod1-R peptide. The synthesis of the construct is now established and antimicrobial testing showed strong antimicrobial activity against gram-positive and gram-negative bacteria. Biomimetic apatites substituted with 15 % of Zn, 10 % and 0.5 % of Cu and 0.5 % of Ag were synthesized by the coprecipitation method at room temperature and were fully characterised. Optimisation of spin coating with ion-substituted apatites of pretreated TA6V substrates was completed. Silver and zinc nanoparticles were successfully incorporated into the polyglycolide polyelectrolyte multilayers and were fully characterised. Silver and Zinc nanoparticles were also successfully incorporated into Ca deficient hydroxyapatite, as well as coatings of co-deposited silver TiO2 and ZnO by magnetron sputtering, were successfully prepared and characterised. The formation of hierarchical micro/nanopatterns on ceramic, ceramic/polymer composites and metal substrates by ultra-short laser surface treatments to modify topographic parameters and material physicochemical properties for orthopaedic applications was achieved. Laser-induced periodic surface nanostructures (LIPSS), combined with micro modification, created a complex surface structure that exhibited improved antibacterial behaviour. 3D constructs from poly- ε- caprolactone (PCL) and 3D TCP, ZrO2/HA were printed. The laser surface treatments resulted in improved surface characteristics and biological properties without altering the surface physicochemical properties. On the biological evaluation front, emphasis was given to the generation of osteoclasts from magnetically sorted CD14+ human monocytes as well as osteoblast induction of human Mesenchymal Stem cells (MSCs) and MG63 in normal and exosome depleted serum followed by exosome isolation and characterization. The effect of the osteoblast-derived exosomes on osteoclast differentiation was studied. Finally, there was great support from the U.Porto on the antimicrobial and biological evaluation of laser-treated metals, ceramics and polymers prepared by a number of ESRs in the project. AIMed is playing a role in the creation of new standards in the area of antimicrobial properties of implants. This activity progressed during this period by the formation of the new ISO working group 16 by the team in INPT. The team attended several meetings with various ISO committees and has established links with ISO, CEN and ASTM committees. The team reviewed and analysed existing standards and the results obtained by ESR04 and 05 are used to draft expected new standards.
There has been significant novelty achieved especially in the area of peptide synthesis and hydrogel development. An example is the antimicrobial construct of the human elastin-like polypeptide with antimicrobial domains using one of the antimicrobial peptide sequences designed at UoB. This progress revealed a number of applications of the antimicrobial HELP in wound healing, drug delivery, tissue engineering and 3D bioprinting. As a result, the collaboration with the team in UNITS has expanded to other members and new funding applications are in the pipeline to develop further the construct through translational research to clinical applications. The success of the laser-treated surfaces in terms of antibacterial activity has led to further collaborations with the team in IE-BAS and the generation of further funding to explore antiviral activity with future implications for the way metal surfaces are treated in high-traffic scenarios such as hospitals and nursing homes.