All Publications

  • Label-Free Composition Analysis of Supramolecular Polymer-Nanoparticle Hydrogels by Reversed-Phase Liquid Chromatography Coupled with a Charged Aerosol Detector. Analytical chemistry Tang, S., Pederson, Z., Meany, E. L., Yen, C., Swansiger, A. K., Prell, J. S., Chen, B., Grosskopf, A. K., Eckman, N., Jiang, G., Baillet, J., Pellett, J. D., Appel, E. A. 2024


    Supramolecular hydrogels formed through polymer-nanoparticle interactions are promising biocompatible materials for translational medicines. This class of hydrogels exhibits shear-thinning behavior and rapid recovery of mechanical properties, providing desirable attributes for formulating sprayable and injectable therapeutics. Characterization of hydrogel composition and loading of encapsulated drugs is critical to achieving the desired rheological behavior as well as tunable in vitro and in vivo payload release kinetics. However, quantitation of hydrogel composition is challenging due to material complexity, heterogeneity, high molecular weight, and the lack of chromophores. Here, we present a label-free approach to simultaneously determine hydrogel polymeric components and encapsulated payloads by coupling a reversed phase liquid chromatographic method with a charged aerosol detector (RPLC-CAD). The hydrogel studied consists of modified hydroxypropylmethylcellulose, self-assembled PEG-b-PLA nanoparticles, and a therapeutic compound, bimatoprost. The three components were resolved and quantitated using the RPLC-CAD method with a C4 stationary phase. The method demonstrated robust performance, applicability to alternative cargos (i.e., proteins) and was suitable for composition analysis as well as for evaluating in vitro release of cargos from the hydrogel. Moreover, this method can be used to monitor polymer degradation and material stability, which can be further elucidated by coupling the RPLC method with (1) a multi-angle light scattering detector (RPLC-MALS) or (2) high resolution mass spectrometry (RPLC-MS) and a Fourier-transform based deconvolution algorithm. We envision that this analytical strategy could be generalized to characterize critical quality attributes of other classes of supramolecular hydrogels, establish structure-property relationships, and provide rational design guidance in hydrogel drug product development.

    View details for DOI 10.1021/acs.analchem.3c05747

    View details for PubMedID 38567987

  • A Regimen Compression Strategy for Commercial Vaccines Leveraging an Injectable Hydrogel Depot Technology for Sustained Vaccine Exposure ADVANCED THERAPEUTICS Yan, J., Ou, B. S., Saouaf, O. M., Meany, E. L., Eckman, N., Appel, E. A. 2023
  • A freely suspended robotic swimmer propelled by viscoelastic normal stresses JOURNAL OF FLUID MECHANICS Kroo, L. A., Binagia, J. P., Eckman, N., Prakash, M., Shaqfeh, E. G. 2022; 944
  • In Situ Direct Laser Writing of 3D Graphene-Laden Microstructures ADVANCED MATERIALS TECHNOLOGIES Restaino, M., Eckman, N., Alsharhan, A. T., Lamont, A. C., Anderson, J., Weinstein, D., Hall, A., Sochol, R. D. 2021; 6 (8)
  • Ignition and combustion analysis of direct write fabricated aluminum/metal oxide/PVDF films COMBUSTION AND FLAME Rehwoldt, M. C., Wang, H., Kline, D. J., Wu, T., Eckman, N., Wang, P., Agrawal, N. R., Zachariah, M. R. 2020; 211: 260-269
  • Why does adding a poor thermal conductor increase propagation rate in solid propellants? APPLIED PHYSICS LETTERS Kline, D. J., Rehwoldt, M. C., Wang, H., Eckman, N. E., Zachariah, M. R. 2019; 115 (11)

    View details for DOI 10.1063/1.5113612

    View details for Web of Science ID 000486002700007

  • Direct Writing of a 90 wt% Particle Loading Nanothermite ADVANCED MATERIALS Wang, H., Shen, J., Kline, D. J., Eckman, N., Agrawal, N. R., Wu, T., Wang, P., Zachariah, M. R. 2019; 31 (23): e1806575


    The additive manufacturing of energetic materials has received worldwide attention. Here, an ink formulation is developed with only 10 wt% of polymers, which can bind a 90 wt% nanothermite using a simple direct-writing approach. The key additive in the ink is a hybrid polymer of poly(vinylidene fluoride) (PVDF) and hydroxy propyl methyl cellulose (HPMC) in which the former serves as an energetic initiator and a binder, and the latter is a thickening agent and the other binder, which can form a gel. The rheological shear-thinning properties of the ink are critical to making the formulation at such high loadings printable. The Young's modulus of the printed stick is found to compare favorably with that of poly(tetrafluoroethylene) (PTFE), with a particle packing density at the theoretical maximum. The linear burn rate, mass burn rate, flame temperature, and heat flux are found to be easily adjusted by varying the fuel/oxidizer ratio. The average flame temperatures are as high as ≈2800 K with near-complete combustion being evident upon examination of the postcombustion products.

    View details for DOI 10.1002/adma.201806575

    View details for Web of Science ID 000474087100019

    View details for PubMedID 30993751