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Álvarez S, Morales J, Tiozzo-Lyon P, Berrios P, Barraza V, Simpson K, Ravasio A, Monforte Vila X, Teuschl-Woller A, Schuh CMAP, Aguayo S. Microfabrication-based engineering of biomimetic dentin-like constructs to simulate dental aging. LAB ON A CHIP 2024; 24:1648-1657. [PMID: 38291999 DOI: 10.1039/d3lc00761h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Human dentin is a highly organized dental tissue displaying a complex microarchitecture consisting of micrometer-sized tubules encased in a mineralized type-I collagen matrix. As such, it serves as an important substrate for the adhesion of microbial colonizers and oral biofilm formation in the context of dental caries disease, including root caries in the elderly. Despite this issue, there remains a current lack of effective biomimetic in vitro dentin models that facilitate the study of oral microbial adhesion by considering the surface architecture at the micro- and nanoscales. Therefore, the aim of this study was to develop a novel in vitro microfabricated biomimetic dentin surface that simulates the complex surface microarchitecture of exposed dentin. For this, a combination of soft lithography microfabrication and biomaterial science approaches were employed to construct a micropitted PDMS substrate functionalized with mineralized type-I collagen. These dentin analogs were subsequently glycated with methylglyoxal (MGO) to simulate dentin matrix aging in vitro and analyzed utilizing an interdisciplinary array of techniques including atomic force microscopy (AFM), elemental analysis, and electron microscopy. AFM force-mapping demonstrated that the nanomechanical properties of the biomimetic constructs were within the expected biological parameters, and that mineralization was mostly predominated by hydroxyapatite deposition. Finally, dual-species biofilms of Streptococcus mutans and Candida albicans were grown and characterized on the biofunctionalized PDMS microchips, demonstrating biofilm-specific morphologic characteristics and confirming the suitability of this model for the study of early biofilm formation under controlled conditions. Overall, we expect that this novel biomimetic dentin model could serve as an in vitro platform to study oral biofilm formation or dentin-biomaterial bonding in the laboratory without the need for animal or human tooth samples in the future.
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Affiliation(s)
- Simon Álvarez
- Dentistry School, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
- School of Medicine, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Jose Morales
- Dentistry School, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Paola Tiozzo-Lyon
- Dentistry School, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Pablo Berrios
- Dentistry School, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Valentina Barraza
- Dentistry School, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.
| | - Kevin Simpson
- Department of Physics, Faculty of Physical and Mathematical Sciences, Universidad de Chile, Santiago, Chile
| | - Andrea Ravasio
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Xavier Monforte Vila
- Department Life Science Engineering, University of Applied Sciences Technikum Wien, Vienna, Austria
- Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Andreas Teuschl-Woller
- Department Life Science Engineering, University of Applied Sciences Technikum Wien, Vienna, Austria
- Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Christina M A P Schuh
- Centro de Medicina Regenerativa, Facultad de Medicina, Clínica Alemana-Universidad del Desarrollo, Santiago, Chile
| | - Sebastian Aguayo
- Dentistry School, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
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Hui WH, Chen YL, Chang SW. Effects of aging and diabetes on the deformation mechanisms and molecular structural characteristics of collagen fibrils under daily activity. Int J Biol Macromol 2024; 254:127603. [PMID: 37871726 DOI: 10.1016/j.ijbiomac.2023.127603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/06/2023] [Accepted: 10/19/2023] [Indexed: 10/25/2023]
Abstract
Crosslinking plays an important role in collagen-based tissues since it affects mechanical behavior and tissue metabolism. Aging and diabetes affect the type and density of crosslinking, effectively altering tissue properties. However, most studies focus on these effects under large stress rather than daily activities. We focus on the deformation mechanisms and structural change at the binding sites for integrins, proteoglycans, and collagenase in collagen fibrils using a fully atomistic model. We show that high-connectivity enzymatic crosslinking (our "HC" model, representing normal tissues) and advanced-glycation end-products (our "Glucosepane" model, which increase in diabetes) result in uniform deformation under daily activity, but low-connectivity enzymatic crosslinking (our "LC" model, representing aging tissues) does not. In particular, the HC model displays more sliding, which may explain the ability of healthy tissues to absorb more strain energy. In contrast, AGEs induce instability in the structures near the binding sites, which would affect the tissue metabolism of the collagen molecule. Our results provide important insights into the molecular mechanisms of collagen and a possible explanation for the role of crosslinking in tissues undergoing daily activity.
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Affiliation(s)
- Wei-Han Hui
- Department of Civil Engineering, National Taiwan University, Taipei City, Taiwan
| | - Yen-Lin Chen
- Department of Civil Engineering, National Taiwan University, Taipei City, Taiwan
| | - Shu-Wei Chang
- Department of Civil Engineering, National Taiwan University, Taipei City, Taiwan; Department of Biomedical Engineering, National Taiwan University, Taipei City, Taiwan.
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Cho DH, Aguayo S, Cartagena-Rivera AX. Atomic force microscopy-mediated mechanobiological profiling of complex human tissues. Biomaterials 2023; 303:122389. [PMID: 37988897 PMCID: PMC10842832 DOI: 10.1016/j.biomaterials.2023.122389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 10/30/2023] [Accepted: 11/04/2023] [Indexed: 11/23/2023]
Abstract
Tissue mechanobiology is an emerging field with the overarching goal of understanding the interplay between biophysical and biochemical responses affecting development, physiology, and disease. Changes in mechanical properties including stiffness and viscosity have been shown to describe how cells and tissues respond to mechanical cues and modify critical biological functions. To quantitatively characterize the mechanical properties of tissues at physiologically relevant conditions, atomic force microscopy (AFM) has emerged as a highly versatile biomechanical technology. In this review, we describe the fundamental principles of AFM, typical AFM modalities used for tissue mechanics, and commonly used elastic and viscoelastic contact mechanics models to characterize complex human tissues. Furthermore, we discuss the application of AFM-based mechanobiology to characterize the mechanical responses within complex human tissues to track their developmental, physiological/functional, and diseased states, including oral, hearing, and cancer-related tissues. Finally, we discuss the current outlook and challenges to further advance the field of tissue mechanobiology. Altogether, AFM-based tissue mechanobiology provides a mechanistic understanding of biological processes governing the unique functions of tissues.
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Affiliation(s)
- David H Cho
- Section on Mechanobiology, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, USA
| | - Sebastian Aguayo
- Dentistry School, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile; Schools of Engineering, Medicine, and Biological Sciences, Institute for Biological and Medical Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Alexander X Cartagena-Rivera
- Section on Mechanobiology, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, USA.
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Leiva-Sabadini C, Schuh CM, Barrera NP, Aguayo S. Ultrastructural characterisation of young and aged dental enamel by atomic force microscopy. J Microsc 2022; 288:185-192. [PMID: 35621144 DOI: 10.1111/jmi.13126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 04/28/2022] [Accepted: 05/19/2022] [Indexed: 11/28/2022]
Abstract
Recent advances in atomic force microscopy (AFM) have allowed the characterisation of dental-associated biomaterials and biological surfaces with high-resolution. 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 intermittent contact (AC mode) imaging, HA crystals were characterised in both transversal and longitudinal orientation (respect to surface plane) with high-resolution in environmental conditions. The external enamel surface displayed the presence of a pellicle-like coating on its surface, that was not observable on cleaned specimens. Acid-etching exposed crystals that were imaged and morphologically characterised in high-resolution 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. 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. Lay abstract: Currently, advanced microscopy techniques such as atomic force microscopy (AFM) can be used to characterise surfaces relevant to dentistry with great detail. Among these surfaces of interest, dental enamel - the hardest mineralised tissue in the body- is important as it protects the deeper areas of the tooth from harmful stimuli such as sudden temperature changes, bacterial penetration, and chemical attack. Also, dental enamel is an important surface for the adhesion of some types of dental restorations; thus, its structure and organisation is highly relevant for both dental scientists and clinicians. With age, teeth are known to suffer changes that can impact their structural stability and function; however, changes in enamel structure as a result of ageing have not yet been explored with nanoscale resolution. It is necessary to develop and optimise AFM-based techniques in order to process specimens from dental samples across different age groups for ageing-associated nanoscale studies in the future. Therefore, the aim of this investigation was to optimise an approach to characterise the ultrastructure of dental enamel and determine potential differences in enamel topography, hydroxyapatite (HA) crystal size, and surface roughness at the nanoscale associated to ageing. For this, human enamel specimens obtained from a total of six teeth were collected and analysed with AFM, and HA crystals were characterised in both transversal and longitudinal orientation with high-resolution in environmental conditions. Upon AFM observation, sound superficial enamel displayed the presence of a pellicle-like coating on its surface, that was not observable after specimens were cleaned. Furthermore, acid-etching exposed HA crystals that were imaged and morphologically characterised in high-resolution at the nanoscale across different regions of enamel in older and younger specimens. We observed important individual variations in HA crystal width and roughness parameters across the analysed specimens and groups, suggesting individual as well as age-associated differences. Overall, high-resolution AFM was an effective approach for the qualitative and quantitative characterisation of human dental enamel ultrastructure at the nanometer range with minimal sample preparation. This proof-of-concept work can pave the way for future studies employing increased sample sizes to compensate for individual differences and population level factors. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Camila Leiva-Sabadini
- School of Dentistry, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Christina Map Schuh
- Centro de Medicina Regenerativa, Facultad de Medicina Clínica Alemana-Universidad del Desarrollo, Santiago, Chile
| | - Nelson P Barrera
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Sebastian Aguayo
- School of Dentistry, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.,Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
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