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Mateusz Cieśluk,1 Katarzyna Pogoda,2 Piotr Deptuła,1 Paulina Werel,3 Alina Kułakowska,3 Jan Kochanowicz,3 Zenon Mariak,4 Tomasz Łysoń,4 Joanna Reszeć,5 Robert Bucki1 1Department of Medical Microbiology and Nanobiomedical Engineering, Medical University of Bialystok, Bialystok PL-15222, Poland; 2Institute of Nuclear Physics, Polish Academy of Sciences, Krakow PL-31342, Poland; 3Department of Neurology, Medical University of Bialystok, Bialystok PL-15276, Poland; 4Department of Neurosurgery, Medical University of Bialystok, Bialystok PL-15276, Poland; 5Department of Pathology, Medical University of Bialystok, Bialystok PL-15269, PolandCorrespondence: Robert BuckiDepartment of Medical Microbiology and Nanobiomedical Engineering, Medical University of Bialystok, Mickiewicza 2C, Bialystok 15-222, PolandTel +48 85 784 5483Email buckirobert@gmail.comBackground: The tissue-mechanics environment plays a crucial role in human brain physiological development and the pathogenesis of different diseases, especially cancer. Assessment of alterations in brain mechanical properties during cancer progression might provide important information about possible tissue abnormalities with clinical relevance.Methods: With atomic force microscopy (AFM), the stiffness of freshly removed human brain tumor tissue was determined on various regions of the sample and compared to the stiffness of healthy human brain tissue that was removed during neurosurgery to gain access to tumor mass. An advantage of indentation measurement using AFM is the small volume of tissue required and high resolution at the single-cell level.Results: Our results showed great heterogeneity of stiffness within metastatic cancer or primary high-grade gliomas compared to healthy tissue. That effect was not clearly visible in lower-grade tumors like meningioma.Conclusion: Collected data indicate that AFM might serve as a diagnostic tool in the assessment of human brain tissue stiffness in the process of recognizing tumors.Keywords: AFM, brain tumors, human tissue rheology, mechanomarkers, glioblastoma

Grażyna Tokajuk,1,2 Katarzyna Niemirowicz,1 Piotr Deptuła,1,3 Ewelina Piktel,1 Mateusz Cieśluk,1 Agnieszka Z Wilczewska,4 Jan R Dąbrowski,3 Robert Bucki1 1Department of Microbiological and Nanobiomedical Engineering, Medical University of Białystok, 2Department of Intergrated Dentistry, Medical University of Białystok, 3Department of Materials and Biomedical Engineering, Białystok University of Technology, 4Institute of Chemistry, University of Białystok, Białystok, Poland Abstract: Nanotechnology offers new tools for developing therapies to prevent and treat oral infections, particularly biofilm-dependent disorders, such as dental plaques and endodontic and periodontal diseases. Chlorhexidine (CHX) is a well-characterized antiseptic agent used in dentistry with broad spectrum activity. However, its application is limited due to inactivation in body fluid and cytotoxicity toward human cells, particularly at high concentrations. To overcome these limitations, we synthesized nanosystems composed of aminosilane-coated magnetic nanoparticles functionalized with chlorhexidine (MNP@CHX). In the presence of human saliva, MNPs@CHX displayed significantly greater bactericidal and fungicidal activity against planktonic and biofilm-forming microorganisms than free CHX. In addition, CHX attached to MNPs has an increased ability to restrict the growth of mixed-species biofilms compared to free CHX. The observed depolarization of mitochondria in fungal cells treated with MNP@CHX suggests that induction of oxidative stress and oxidation of fungal structures may be a part of the mechanism responsible for pathogen killing. Nanoparticles functionalized by CHX did not affect host cell proliferation or their ability to release the proinflammatory cytokine, IL-8. The use of MNPs as a carrier of CHX has great potential for the development of antiseptic nanosystems. Keywords: chlorhexidine, magnetic nanoparticles, antimicrobial properties, anti-biofilm