Browsing by Author "Leiva Sabadini, Camila Andrea"

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    Biofilm formation on collagen substrates modulates Streptococcus mutans bacterial extracellular nanovesicle production and cargo
    (2025) Leiva Sabadini, Camila Andrea; Berríos Segovia, Pablo Germán; Saavedra Godoy, Paula Andrea; Carrasco Rojas, Javiera; González Aramundiz, José Vicente; Vera Véliz, Mario Andrés; Tarifeño Saldivia, Estefanía; Schuh, Christina M. A. P.; Aguayo Paul, Sebastián
    Streptococcus mutans is the major microbial etiological agent of dental caries and can adhere to surfaces such as type-I collagen, which is present in dentin and periodontal tissues. Recent studies have characterized planktonic S. mutans bacterial extracellular vesicles (bEVs) at the nanoscale range and demonstrated environmental-induced changes due to sugar presence or pH alterations. However, to date, no studies have explored whether surface-derived changes can modulate bEV production in the context of oral biofilm formation in the elderly. Therefore, this work aimed to determine the role of biofilm formation and collagen glycation on the nanoscale morphology and proteomic composition of S. mutans bEVs. For this, bEVs from S. mutans biofilms on native and glycated collagen surfaces were isolated, characterized, and compared to bEVs from planktonic cells. Nanoparticle tracking analysis (NTA), atomic force microscopy (AFM), and electron microscopy confirmed bEV production and showed that bEVs from biofilms are smaller in size and less abundant than those from planktonic cells. Furthermore, proteome analysis revealed that S. mutans biofilm formation on native and glycated collagen led to the enrichment of several key virulence proteins. Also, a shift towards proteins involved in metabolic processes was found in bEVs following biofilm formation on collagen surfaces, whereas glucan metabolism proteins were overexpressed in vesicles from the planktonic state. These results demonstrate that biofilm formation, as well as the glycation of collagen associated with aging and hyperglycaemia, can modulate bEV characteristics and cargo and could play a central role in S. mutans virulence and the development of diseases such as dental caries and periodontal disease.
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    Ultrastructural characterisation of young and aged dental enamel by atomic force microscopy
    (2022) Leiva Sabadini, Camila Andrea; Schuh, Christina MAP; Barrera Rojas, Nelson Patricio; Aguayo Paul, Sebastián
    Recent advances in atomic force microscopy (AFM) have allowed the characterisation of dental-associated biomaterials and biological surfaces with high-resolution and minimal sample preparation. In this context, the topography of dental enamel – the hardest mineralised tissue in the body – has been explored with AFM-based approaches at the micro-scale. With age, teeth are known to suffer changes that can impact their structural stability and function; however, changes in enamel structure because of ageing have not yet been explored with nanoscale resolution. Therefore, the aim of this exploratory work was to optimise an approach to characterise the ultrastructure of dental enamel and determine potential differences in topography, hydroxyapatite (HA) crystal size, and surface roughness at the nanoscale associated to ageing. For this, a total of six teeth were collected from human donors from which enamel specimens were prepared. By employing AC mode imaging, HA crystals were characterised in both transversal and longitudinal orientation with high-resolution in environmental conditions. Sound superficial enamel displayed the presence of a pellicle-like coating on its surface, that was not observable on cleaned specimens. Acidetching exposed crystals that were imaged and morphologically characterised in highresolution at the nanoscale in both the external and internal regions of enamel in older and younger specimens. Our results demonstrated important individual variations in HA crystal width and roughness parameters across the analysed specimens; however, an increase in surface roughness and decrease in HA width was observed for the pooled older external enamel group compared to younger specimens. Overall, high-resolution AFM was an effective approach for the qualitative and quantitative characterisation of human dental enamel ultrastructure at the nanometre range. Future work should focus on exploring the ageing of dental enamel with increased sample sizes to compensate for individual differences as well as other potential confounding factors such as behavioural habits and mechanical forces.