Infection under the ion beam : focused ion beams and antibacterial properties of biomaterials
In this thesis, Helium Ion Microscopy (HIM) imaging and milling on organic and antibacterial materials will be discussed. In addition, I will discuss the antibacterial properties of surface-immobilized bacteriophages. HIM is a recently developed imaging method, which is especially suitable for biological samples because they can be imaged without a metal coating. Because of the state-of-the-art ion source, the microscope has also a higher imaging resolution compared to the scanning electron microscope (SEM). The suitability of HIM imaging for the bacteria-phage interactions is discussed in addition to the more delicate nanocellulose samples. High beam damage on the cellulose was found which has not been reported previously with HIM. Indeed an ion beam can have a milling property, which is demonstrated here with bacteria, bacteria-dragonfly interactions and encapsulated bacteriophages to obtain volumetric information. The antibacterial effectivity of immobilized bacteriophages was analyzed quantitatively with HIM-imaging and biological measures. It was found that detaching phages from the material are likely the major contributor to the infectivity of the phage-biomaterial. ...
- Artikkeli I: Leppänen, Miika; Maasilta, Ilari; Sundberg, Lotta-Riina (2019). Antibacterial efficiency of surface-immobilized Flavobacterium-infecting bacteriophage. ACS Applied Bio Materials, 2 (11), 4720-4727. DOI: 10.1021/acsabm.9b00242
- Artikkeli II: Leppänen, M., Sundberg, L.-R., Laanto, E., De Freitas Almeida, G., Papponen, P., & Maasilta, I. (2017). Imaging Bacterial Colonies and Phage-Bacterium Interaction at Sub-Nanometer Resolution Using Helium-Ion Microscopy. Advanced Biosystems, 1 (8), 1700070. DOI: 10.1002/adbi.201700070
- Artikkeli III: Ketola, A. E., Leppänen, M., Turpeinen, T., Papponen, P., Strand, A., Sundberg, A., . . . , & Retulainen, E. (2019). Cellulose nanofibrils prepared by gentle drying methods reveal the limits of helium ion microscopy imaging. RSC Advances, 9 (27), 15668-15677. DOI: 10.1039/C9RA01447K
- Artikkeli IV: Vinner, G. K., Rezaie-Yazdi, Z., Leppänen, M., Stapley, A. G. F., Leaper, M. C., & Malik, D. J. (2019). Microencapsulation of Salmonella-Specific Bacteriophage Felix O1 Using Spray-Drying in a pH-Responsive Formulation and Direct Compression Tableting of Powders into a Solid Oral Dosage Form. Pharmaceuticals, 12 (1), 43. DOI: 10.3390/ph12010043
- Artikkeli V: Vinner, Gurinder K.; Richards, Kerry; Leppänen, Miika; Sagona, Antonia P.; Malik 1, Danish J. (2019). Microencapsulation of Enteric Bacteriophages in a pH-Responsive Solid Oral Dosage Formulation Using a Scalable Membrane Emulsification Process. Pharmaceutics, 11 (9), 475. DOI: 10.3390/pharmaceutics11090475
- Artikkeli VI: Bandara, Chaturanga D.; Ballerin, Giulia; Leppänen, Miika; Tesfamichael, Tuquabo; Ostrikov, Kostya (Ken); Whitchurch, Cynthia B. (2020). Resolving Bio-Nano Interactions of E.coli Bacteria-Dragonfly Wing Interface with Helium Ion and 3D-Structured Illumination Microscopy to Understand Bacterial Death on Nanotopography. ACS Biomaterials Science & Engineering, 6 (7), 3925-3932. DOI: 10.1021/acsbiomaterials.9b01973
- Artikkeli VII: De Freitas Almeida, G., Leppänen, M., Maasilta, I., & Sundberg, L.-R. (2018). Bacteriophage imaging : past, present and future. Research in Microbiology, 169 (9), 488-494. DOI: 10.1016/j.resmic.2018.05.006
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Leppänen, Miika; Maasilta, Ilari; Sundberg, Lotta-Riina (American Chemical Society, 2019)Control of bacterial diseases by bacteriophages (phages) is gaining more interest due to increasing antibiotic resistance. This has led to technologies to attach phages on surfaces to form a biomaterial that can functionally ...
Comparison of Delivery Methods in Phage Therapy against Flavobacterium columnare Infections in Rainbow Trout Kunttu, Heidi M. T.; Runtuvuori-Salmela, Anniina; Middelboe, Mathias; Clark, Jason; Sundberg, Lotta-Riina (MDPI AG, 2021)Viruses of bacteria, bacteriophages, specifically infect their bacterial hosts with minimal effects on the surrounding microbiota. They have the potential to be used in the prevention and treatment of bacterial infections, ...
Almeida, Gabriel M. F.; Laanto, Elina; Ashrafi, Roghaleh; Sundberg, Lotta-Riina (American Society for Microbiology, 2019)Metazoans were proposed to host bacteriophages on their mucosal surfaces in a symbiotic relationship, where phages provide an external immunity against bacterial infections and the metazoans provide phages a medium for ...
de Freitas Almeida, Gabriel Magno; Sundberg, Lotta-Riina (Elsevier, 2020)The use of bacteriophages to treat bacterial infections (known as phage therapy) is considered a possible solution to the antimicrobial resistance crisis. However, phage therapy is not a new concept. The discovery of phages ...
Microencapsulation of Enteric Bacteriophages in a pH-Responsive Solid Oral Dosage Formulation Using a Scalable Membrane Emulsification Process Vinner, Gurinder K.; Richards, Kerry; Leppänen, Miika; Sagona, Antonia P.; Malik 1, Danish J. (MDPI, 2019)A scalable low-shear membrane emulsification process was used to produce microencapsulated Escherichia coli-phages in a solid oral dosage form. Uniform pH-responsive composite microparticles (mean size ~100 µm) composed ...