Whitlockite -A study on the effect of reaction parameters on morphology in one-solvent system

Abstract

Whitlockite (WK) is a hierarchically self-assembled and second most abundant biomineral in a naturally occurring complex bone at the nanoscale. Most of the properties at the nanoscale are size and shape-dependent. However, single-phase synthesis of WK is challenging and is pH and temperature-dependent. This work reports the different shapes and sizes of a novel bone-regenerative mineral (whitlockite) in a one-solvent system. We designed and investigated the synthetic conditions to achieve morphologically different WK nanostructures by fine-tuning the precursor's proportion, pH, temperature, and ageing. By manipulating the pH to 5.4, we successfully synthesised irregular plates of pure WK nanostructures. Conversely, through temperature control within the range of 90 °C–100 °C, various morphologies of pure whitlockite, such as cubes, irregular plates, clusters, and spheres, were attained. However, elongated clusters of WK structures were obtained after ageing the solution for three days at 90 °C. A broader particle size distribution was achieved within the 76.4 nm to 1 μm range. The purity, crystallinity, formation of auxiliary phases, functional groups, shapes, sizes, and elemental composition were investigated through correlative analytical approaches encompassing XRD, FTIR, Raman, SEM and EDS.