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1. Rapid fabrication of collagen bundles mimicking tumor-associated collagen architectures

   https://doi.org/10.1016/j.actbio.2020.03.019  

   Gong, Xiangyu; Kulwatno, Jonathan; Mills, K.L. (May 2020, Acta Biomaterialia)

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2. MICROMECHANICAL MODEL OF MECHANOSENSITIVE COLLAGEN TISSUES

   Kalyn G. Younger, William Cortes (June 2023, Summer Biomechanics, Bioengineering and Biotransport Conference Foundation)
3. MICROMECHANICAL MODEL OF MECHANOSENSITIVE COLLAGEN TISSUES

   Younger, Kalyn G; Cortes, William; Reich, Daniel H; Nguyen, Thao D (June 2022, Summer Biomechanics, Bioengineering and Biotransport Conference)

   The mechanical behavior of soft collagenous tissues is largely influenced by the reinforcing collagen fiber microstructure. The anisotropic collagen microstructure can remodel in response to changes in mechanical loading, which can dramatically alter the mechanical properties of the tissues and the mechanical environment of the resident cells. It is important to study the remodeling mechanisms of collagen tissues to understand the pathophysiology of various connective tissue diseases. We hypothesize that the collagen structure actively changes in response to mechanical stimuli through concurrent processes of collagen deposition and degradation and that the rates of these processes are altered by collagen mechanochemistry, mechanosensitive collagen production, and cellular contraction. In prior studies, we developed micromechanical models of collagen tissues to investigate the role of collagen mechanochemistry and mechanosensitive collagen production in remodeling the collagen fiber structure and tissue growth.[1,2] We found that stress inhibition of enzymatic degradation and stimulation of collagen production can explain many phenomena, including remodeling the anisotropic collagen structure along the directions of the maximum principal stress and the development of stress homeostasis. The goal of this study is to investigate the effect of mechanical loading on the active behavior of the cells. Our approach uses a model 3D microtissue systems, self-assembled on a magnetically actuated two-pillar system (µTUG), to investigate these cell-collagen interactions and effects of mechanical loading. The micropillar support allows for measurement of the active cellular contraction, while the magnetic tweezer allows for mechanical testing of the microtissue under a controlled stress rate. Digital image analysis is applied to measure the local two-dimensional (2D) strain field. To analyze the mechanical measurements for mechanical properties of the collagen structure and active behavior of the cells, we developed a micromechanical model for the mechanical behavior of the microtissue. The micromechanical model includes the elastic behavior of the anisotropic collagen structure and the anisotropic active behavior of the cells. To describe mechanosensitive cellular contraction, we assume concurrent polymerization/depolymerization of actin filaments, where the polymerization rate increases with the fiber stress. In this paper, we will briefly summarize the model and describe an initial model validation by comparing to µTUG experiments measuring the stress-strain behavior of the microtissue to load-unload tests. 

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4. Incorporation of Azapeptoid Residues Into Collagen

   https://doi.org/10.1002/pep2.70008  

   Wright, Madison M; Rathman, Benjamin M; Del_Valle, Juan R (September 2025, Peptide Science)

   Collagen, the major structural protein in connective tissue, adopts a right‐handed triple helix composed of peptide chains featuring repeating Gly‐Xaa‐Yaa tripeptide motifs. While the cyclic residues proline (Pro) and hydroxyproline (Hyp) are prevalent in the Xaa and Yaa positions due to their PPII‐favoring conformational properties, diverse acyclic peptoid (N‐alkylated Gly) residues can also stabilize the collagen fold. Here, we investigated the effects of N‐aminoglycine (aGly) derivatives—so‐called “azapeptoid” residues—on the thermal stability of collagen mimetic peptides (CMPs). Substitution of Pro at the central Xaa11 position with aGly resulted in destabilization of the triple helix, yet the introduction of select N′‐alkyl groups (isopropyl, butyl) partially restored thermal stability. Moreover, the N‐amino group of azapeptoid residues enhanced thermal CMP stability relative to an unsubstituted Gly analog. Kinetic studies revealed that the introduction of the hydrazide bonds in aGly and (iPr)aGly CMPs did not significantly impact triple helix refolding rates. Their modular late‐stage derivatization and tunable properties highlight azapeptoid residues as potentially valuable tools for engineering CMPs and probing the structural determinants of collagen folding. 

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5. Modulating Mechanical Properties of Collagen–Lignin Composites

   https://doi.org/10.1021/acsabm.9b00444  

   Belgodere, Jorge A.; Zamin, Syed A.; Kalinoski, Ryan M.; Astete, Carlos E.; Penrod, Joseph C.; Hamel, Katie M.; Lynn, Bert C.; Rudra, Jai S.; Shi, Jian; Jung, Jangwook P. (June 2019, ACS Applied Bio Materials)