@article{perera_black_islam_ryu_corder_khan_2024, title={Rheological Behavior and Roll Coating Properties of PDMS Enhanced with Multi-Walled Carbon Nanotubes and Fumed Silica}, volume={2}, ISSN={["2771-9545"]}, url={https://doi.org/10.1021/acsaenm.3c00698}, DOI={10.1021/acsaenm.3c00698}, abstractNote={Scalable manufacturing of micro- and nanoscale textured surfaces from polymer composites is desirable in many applications from drag reduction in ship applications to energy-efficient radiative cooling of infrastructure. Creation of such surfaces, however, remains a challenge. By exploiting the ribbing phenomena that arise when viscous forces dominate over surface tension forces, we can create topographic patterns using roll-to-roll manufacturing techniques. In this work, we analyze how the rheology of yield stress fluids impacts the morphology of roll-coated surfaces using polydimethylsiloxane (PDMS) samples enhanced to varying degrees with multiwalled carbon nanotubes (CNTs) and fumed silica. We observe that CNTs increasingly dominate the large amplitude oscillatory shear response of PDMS composites. However, their impact is modified by the presence of fumed silica, which introduces a transition from intracycle strain softening to hardening behavior. The roll coating behavior of these PDMS composites is examined using image processing to link the rheological properties with the resulting surface morphologies, specifically focusing on two parameters defining surface morphology─ribbing wavenumber and branching patterns. While both types of PDMS composites display comparable wavenumbers, they exhibit different degrees of branching. The deviation in branching can be attributed to the intracycle strain hardening behavior seen at low CNT loadings in PDMS composites containing fumed silica. The study provides insights into the interactions occurring between CNTs and fumed silica in PDMS composites and highlights the significance of analyzing rheological parameters that are relevant at the high strains and strain rates experienced during roll coating, advancing our understanding of ribbing stability in yield stress fluids.}, number={3}, journal={ACS APPLIED ENGINEERING MATERIALS}, author={Perera, Himendra and Black, Benjamin and Islam, Md D. and Ryu, Jong E. and Corder, Ria D. and Khan, Saad A.}, year={2024}, month={Feb}, pages={618–627} } @article{corder_vachieri_martin_taylor_fleming_khan_2023, title={Linear and nonlinear rheology of liberase-treated breast cancer tumors}, volume={1}, ISSN={["2047-4849"]}, url={https://doi.org/10.1039/D3BM00038A}, DOI={10.1039/d3bm00038a}, abstractNote={The effects of injectable, localized liberase treatments on the linear and nonlinear rheology of allograft 4T1 mouse mammary tumors are examined, demonstrating how insights about the tumor microenvironment can be gleaned from the rheological data.}, journal={BIOMATERIALS SCIENCE}, author={Corder, Ria D. and Vachieri, Robert B. and Martin, Megan E. and Taylor, Darlene K. and Fleming, Jodie M. and Khan, Saad A.}, year={2023}, month={Jan} } @article{dufficy_corder_dennis_fedkiw_khan_2021, title={Guar Gel Binders for Silicon Nanoparticle Anodes: Relating Binder Rheology to Electrode Performance}, volume={13}, ISSN={["1944-8252"]}, url={https://doi.org/10.1021/acsami.1c10776}, DOI={10.1021/acsami.1c10776}, abstractNote={Binding agents are a critical component of Si-based anodes for lithium-ion batteries. Herein, we introduce a composite hydrogel binder consisting of carbon black (CB) and guar, which is chemically cross-linked with glutaraldehyde as a means to reinforce the electrode structure during lithiation and improve electronic conductivity. Dynamic rheological measurements are used to monitor the cross-linking reaction and show that rheology plays a significant role in binder performance. The cross-linking reaction occurs at a faster rate and produces stronger networks in the presence of CB, as evidenced from higher gel elastic modulus in guar + CB gels than guar gels alone. Silicon nanoparticle (SiNP) electrodes that use binders with low cross-link densities (trxn < 2 days) demonstrate discharge capacities ∼1200 mAh g-1 and Coulombic efficiencies >99.8% after 300 cycles at 1-C rate. Low cross-link densities likely increase the capacity of SiNP anodes because of binder-Si hydrogen-bonding interactions that accommodate volume expansions. In addition, the cross-linked binder demonstrates the potential for self-healing, as evidenced by an increased elastic modulus after the gel was mechanically fragmented, which may preserve the electrode microstructure during lithiation and increase capacity retention. The composite hydrogel with integrated conductive additives gives promise to a new type of binder for next-generation lithium-ion batteries.}, number={43}, journal={ACS APPLIED MATERIALS & INTERFACES}, publisher={American Chemical Society (ACS)}, author={Dufficy, Martin K. and Corder, Ria D. and Dennis, Kimberly A. and Fedkiw, Peter S. and Khan, Saad A.}, year={2021}, month={Nov}, pages={51403–51413} } @article{corder_gadi_vachieri_jayes_cullen_khan_taylor_2021, title={Using rheology to quantify the effects of localized collagenase treatments on uterine fibroid digestion}, volume={134}, ISSN={["1878-7568"]}, DOI={10.1016/j.actbio.2021.08.003}, abstractNote={Uterine fibroids are stiff, benign tumors containing excessive, disordered collagens that occur in 70-80% of women before age 50 and cause bleeding and pain. Collagenase Clostridium histolyticum (CCH) is a bacterial enzyme capable of digesting the collagens present in fibroids. By combining CCH with injectable drug delivery systems to enhance effectiveness, a new class of treatments could be developed to reduce the stiffness of fibroids, preventing the need for surgical removal and preserving fertility. In this work, we achieved localization of CCH via physical entrapment by co-injecting a thermoresponsive pNIPAM-based polymeric delivery system called LiquoGel (LQG), which undergoes a sol-gel transition upon heating. Toxicity study results for LQG injected subcutaneously into mice demonstrate that LQG does not induce lesions or other adverse effects. We then used rheology to quantify the effects of localized CCH injections on the modulus and viscoelasticity of uterine fibroids, which exhibit gel-like behavior, through ex vivo and in vivo digestion studies. Ex vivo CCH injections reduce the tissue modulus by over two orders of magnitude and co-injection of LQG enhances this effect. Rheological results from an in vivo digestion study in mice show a significant reduction in tissue modulus and increase in tissue viscoelasticity 7 days after a single injection of LQG+CCH. Parallel histological staining validates that the observed rheological changes correspond to an increase in collagen lysis after treatment by LQG+CCH. These results show promise for development of injectable and localized enzymatic therapies for uterine fibroids and other dense tumors. Uterine fibroids are stiff, benign tumors containing high collagen levels that cause bleeding and pain in women. Fertility-preserving and minimally-invasive treatments to soften fibroids are needed as an alternative to surgical removal via hysterectomy. We demonstrate through ex vivo and in vivo studies that co-injecting a thermoresponsive polymer delivery system (LQG) alongside a bacterial collagenase (CCH) enzyme significantly increases treatment effectiveness at softening fibroids through CCH localization. We use rheology to measure the modulus and viscoelasticity of fibroids and histology to show that fibroid softening corresponds to a decrease in collagen after treatment with LQG+CCH. These results highlight the utility of rheology at quantifying tissue properties and present a promising injectable therapy for fibroids and other dense tumors.}, journal={ACTA BIOMATERIALIA}, author={Corder, Ria D. and Gadi, Sashi V and Vachieri, Robert B. and Jayes, Friederike L. and Cullen, John M. and Khan, Saad A. and Taylor, Darlene K.}, year={2021}, month={Oct}, pages={443–452} } @article{wang_ye_yu_kahkoska_zhang_wang_sun_corder_chen_khan_et al., title={Core-Shell Microneedle Gel for Self-Regulated Insulin Delivery}, volume={12}, number={3}, journal={ACS Nano}, author={Wang, J. Q. and Ye, Y. Q. and Yu, J. C. and Kahkoska, A. R. and Zhang, X. D. and Wang, C. and Sun, W. J. and Corder, R. D. and Chen, Z. W. and Khan, S. A. and et al.}, pages={2466–2473} }