Search for: All records

Abstract The low friction nature of articular cartilage has been attributed to the synergistic interaction between lubricin and hyaluronic acid in the synovial fluid (SF). Lubricin is a mucinous glycoprotein that lowers the boundary mode coefficient of friction of articular cartilage in a dose‐dependent manner. While there have been multiple attempts to produce recombinant lubricin and lubricin mimetic cartilage lubricants over the last two decades, these materials have not found clinical use due to challenges associated with large scale production, manufacturing, and purification. Recently, a novel method using codon scrambling was developed to produce a stable, full‐length bioengineered equine lubricin (eLub) in large reproducible quantities. While preliminary frictional analysis of eLub and other recombinantly produced forms revealed they can lubricate cartilage, a complete tribological characterization is lacking, with previous studies evaluating the friction coefficient only at a single dose or a single speed. The objective of this study was to analyze the dose‐dependent tribological properties of eLub using the Stribeck framework of tribological analysis. Recombinantly produced eLub at doses greater than 1.5 mg/mL exhibits friction coefficients on par with healthy bovine SF, and a maximal 5 mg/mL dose exhibits a nearly 50% lower friction coefficient than healthy SF. eLub also modulates the shift in lubrication mode of the cartilage from the high friction boundary mode to the low friction minimum mode at high concentrations. 

Abstract Azimuthal beam scanning eliminates the uneven excitation field arising from laser interference in through-objective total internal reflection fluorescence (TIRF) microscopy. The same principle can be applied to scanning angle interference microscopy (SAIM), where precision control of the scanned laser beam presents unique technical challenges for the builders of custom azimuthal scanning microscopes. Accurate synchronization between the instrument computer, beam scanning system and excitation source is required to collect high quality data and minimize sample damage in SAIM acquisitions. Drawing inspiration from open-source prototyping systems, like the Arduino microcontroller boards, we developed a new instrument control platform to be affordable, easily programmed, and broadly useful, but with integrated, precision analog circuitry and optimized firmware routines tailored to advanced microscopy. We show how the integration of waveform generation, multiplexed analog outputs, and native hardware triggers into a single central hub provides a versatile platform for performing fast circle-scanning acquisitions, including azimuthal scanning SAIM and multiangle TIRF. We also demonstrate how the low communication latency of our hardware platform can reduce image intensity and reconstruction artifacts arising from synchronization errors produced by software control. Our complete platform, including hardware design, firmware, API, and software, is available online for community-based development and collaboration.