Screening of Biomineralization Using Microfluidics

Abstract

Biomineralization is the process where biological systems produce well-defined composite structures such as shell, teeth, and bones. Currently, there is substantial momentum to investigate the processes implicated in biomineralization and to unravel the complex roles of proteins in the control of polymorph switching. An understanding of these processes may have wide-ranging significance in health care applications and in the development of advanced materials. We have demonstrated a microfluidic approach toward these challenges. A reversibly sealed T-junction microfluidic device was fabricated to investigate the influence of extrapallial (EP) fluid proteins in polymorph control of crystal formation in mollusk shells. A range of conditions were investigated on chip, allowing fast screening of various combinations of ion, pH, and protein concentrations. The dynamic formation of crystals was monitored on chip and combined with in situ Raman to reveal the polymorph in real time. To this end, we have demonstrated the unique advantages of this integrated approach in understanding the processes involved in biomineralization and revealing information that is impossible to obtain using traditional methods.

Calcium carbonate polymorph control using droplet-based microfluidics

“…The continuous flow microfluidic system was also associated with a wide distribution of crystals sizes. This has been observed previously for calcium carbonate 21,22 and is unavoidable due to the residence time distributions associated with continuous-flow operation. Importantly, segmented flow reactions do not suffer from such limitations as droplets do not interact with channel walls and therefore move at a constant linear velocity, eliminating residence time distributions.…”

“…To date, the only microfluidic approach reported for the synthesis of calcium carbonate has involved continuous-flow mixing of reagents at a T-junction. 21,22 These proof-of-principle studies demonstrated facile crystal formation, and extraction of crystals for off-chip characterization by scanning electron microscopy (SEM) showed predominantly calcite polymorphs present. Unfortunately, the unavoidable residence time distributions associated with continuous-flow reactors significantly reduce control over reaction times, leading to broad size distributions of the resulting crystals and therefore limited control over the crystal polymorph.…”

Control of crystal polymorph in microfluidics using molluscan 28 kDa Ca2+-binding protein

“…Recently we have demonstrated the potential of microfluidics as a new platform for understanding biomineralisation. 19 Many advantages of microfluidics over bulk systems have been demonstrated such as fast analysis, small sample consumption and excellent reproducibility. 20,21 These advantages have been exploited in life sciences e.g.…”

“…25,26 Real time growth of CaCO 3 crystals in the presence of EP extracts was monitored on-chip with in situ Raman microspectroscopy to determine the resultant crystal polymorph. 19 Here we look specifically at the calcium-binding activity of the most abundant EP protein. We demonstrate the power of microfluidics to probe the complex factors that control biomineralisation, providing insight into the influence of this specific protein that cannot be obtained from experimental crystal growth in bulk solutions.…”

“…1) were made by casting polydimethylsiloxane (PDMS) elastomer against an SU-8 master as described elsewhere. 19 The total length of the serpentine microchannel was 5 cm, with all microchannels having a uniform cross section of 130 mm (width) Â 100 mm (height). The PDMS was clamped against a cleaned glass substrate, forming a reversible seal, and microfluidic interconnects were created using established methods.…”