A multimodal approach to understanding the role of self-assembling peptide P11-4 in guided mineral nucleation for biomimetic dental enamel regeneration using synchrotron X-ray and correlative electron microscopy techniques

High-resolution characterisation of biomaterials across multiple length scales to investigate their effect on (re)mineralisation can inform the development of effective interventions for clinical conditions such as dental caries, a disease with an estimated global economic burden of approximately $245 billion. This thesis presents a multi-modal, synchrotron-based approach on novel instruments to study the role of self-assembling peptide P11-4 in dental enamel (re)mineralisation, with the aim of elucidating its mechanism of action for potential optimisation to treat early caries lesions non-invasively, and to use P11-4 as a model system for the development of a liquid flow cell that can be used to characterise biomimetic materials in situ using synchrotron X-ray diffraction (XRD) and X-ray microtomography (XMT).
X-ray fluorescence combined with differential phase contrast imaging on the I14 beamline, together with XRD and XMT on the Dual Imaging and Diffraction beamline at Diamond Light Source, along with complementary laboratory-based techniques, were employed to characterise P11-4.
P11-4 accelerated the initial kinetics of the mineralisation process compared to the control, via the provision of calcium-binding sites, and controlled the mineral deposition process, mimicking the role of enamel matrix proteins during biomineralisation. The chemical model used for artificial demineralisation to create caries-like lesions resulted in preferential demineralisation of the enamel prisms. Within the caries-like lesions, the developed flow cell demonstrated that P11-4 promoted deep remineralisation of the lesion via the gradual formation of organised apatite structures within one specific population of crystallites, likely corresponding to the prisms. The organisation of crystallites within the regenerated structure is comparable to healthy enamel, highlighting its role in restoring the organised structure lost due to caries, and its significance as a non-invasive clinical treatment.
The methodology presented in this thesis can be applied to analyse lesions and characterise other biomaterials/proteins, and the flow cell is available to other users.