Browsing by Author "Rajachar, Rupak M."

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    Application of sub-micrometer vibrations to mitigate bacterial adhesion.
    Paces, Will R.; Holmes, Hal R.; Vlaisavljevich, Eli; Snyder, Katherine L.; Tan, Ee Lim; Rajachar, Rupak M.; Ong, Keat Ghee (2014-03-11)
    As a prominent concern regarding implantable devices, eliminating the threat of opportunistic bacterial infection represents a significant benefit to both patient health and device function. Current treatment options focus on chemical approaches to negate bacterial adhesion, however, these methods are in some ways limited. The scope of this study was to assess the efficacy of a novel means of modulating bacterial adhesion through the application of vibrations using magnetoelastic materials. Magnetoelastic materials possess unique magnetostrictive property that can convert a magnetic field stimulus into a mechanical deformation. In vitro experiments demonstrated that vibrational loads generated by the magnetoelastic materials significantly reduced the number of adherent bacteria on samples exposed to Escherichia coli, Staphylococcus epidermidis and Staphylococcus aureus suspensions. These experiments demonstrate that vibrational loads from magnetoelastic materials can be used as a post-deployment activated means to deter bacterial adhesion and device infection.
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    Focused ultrasound for the remote modulation of nitric oxide release from injectable PEG-fibrinogen hydrogels for tendon repair
    Meyers, Kaylee M.; Simon, Alex; Khan, Zerin M.; Rajachar, Rupak M.; Vlaisavljevich, Eli (Frontiers, 2023-04)
    Introduction: Tendon disorders such as tendinosis, the degradation of collagen in tendon, or tendonitis, inflammation of tendon tissue, contribute to 30% of musculoskeletal complaints. To address the limitations of currently available treatments for tendon repair, an injectable polyethylene glycol (PEG)fibrinogen hydrogel encompassing nitric oxide (NO) releasing mu-particles was generated. The release of nitric oxide, a therapeutic molecule that modulates many wound healing processes, from the hydrogel can be modified with thermal and mechanical stimulus. To achieve remote control over NO release from hydrogels after deployment, focused ultrasound (FUS) was explored as it provides highly controlled thermal and mechanical stimulus non-invasively. Methods: In this work, the ability of FUS to remotely elicit on-demand NO generation from acoustically active composite hydrogels via thermal and/or mechanical stimulus was explored. Specifically, the temperature and timedependent release of NO was simulated and characterized when applying FUS to composite hydrogels. Results: Results from acoustic simulations as well as thermocouple heating studies indicated that high spatial and temporal control over hydrogel warming could be achieved non-invasively with a 3.5 MHz FUS transducer. FUS was also able to remotely control NO release from hydrogels with various thermal magnitudes and durations. Additionally, no apparent changes in the mechanical properties of hydrogels were observed with FUS treatment. Discussion: Utilizing FUS thermal and mechanical stimulus provides a potential method of remotely controlling NO release from hydrogels at a wound site to aid in tendon repair.