Exploring Gelation and Physicochemical Behavior of in Situ Bioresponsive Silk Hydrogels for Disc Degeneration Therapy

Abstract

Hydrogels have received considerable attention in the field of tissue engineering because of their unique structural and compositional resemblance to the highly hydrated human tissues. In addition, controlled fabrication processes benefit them with desirable physicochemical features for injectability in minimally invasive manner and cell survival within hydrogels. Formulation of biologically active hydrogels with desirable characteristics is one of the prerequisites for successful applications like nucleus pulposus (NP) tissue engineering to address disc degeneration. To achieve such a benchmark, in this study, two naturally derived silk fibroin proteins (Bombyx mori, BM SF; and Antheraea assamensis, AA SF) were blended together to allow self-assembly and transformation to hydrogels in absence of any cross-linker or external stimuli. A comprehensive study on sol–gel transition of fabricated hydrogels in physiological fluid microenvironment (pH, temperature, and ionic strength) was conducted using optical and fluorescence analysis. Tunable gelation time (∼8–40 min) was achieved depending on combinations. The developed hydrogels were validated by extensive physicochemical characterizations which include confirmation of secondary structure, surface morphology, swelling and degradation. Mechanical behavior of the hydrogels was further analyzed in various in vitro-physiological-like conditions with varying pH, ionic strength, diameter, storage time, and strain values to determine their suitability in native physiological environments. Rheological study, cytocompatibility using primary porcine NP cells and ex vivo biomechanics of hydrogels were explored to validate their in situ applicability in minimally invasive manner toward potential disc regeneration therapy.

3D Printing of Functional Microalgal Silk Structures for Environmental Applications

“…The presence of high ion concentration in silk solution lowers the cross-linking efficiency. 40,41 Therefore, when choosing a thickening agent for silk hydrogel printing, the following criteria were considered: (1) room-temperature solubility, (2) easy dissolution in silk fibroin solution, and (3) absence of ionization in aqueous solution. On the basis of these criteria, hydroxypropyl methylcellulose (HPMC) was selected, which is chemically inert and biocompatible.…”

Functional silk fibroin hydrogels: preparation, properties and applications

“…This method is expected to replace cerclage for the treatment of premature birth due to cervical insufficiency. Bibhas K et al 104 mixed two different kinds of silk(i.e., Bombyx mori and Antheraea assamensis) solutions to form an injectable hydrogel through self-assembly. The hydrogel has exhibited the characteristic of fast gelation at 37 °C, with adjustable gel time.…”

Silk‐Based Bioengineered Diaphyseal Cortical Bone Unit Enclosing an Implantable Bone Marrow toward Atrophic Nonunion Grafting

“…Though, there was no significant difference between the groups (static and dynamic), cells encapsulated within the bioink gradually increased from day‐1 and day‐14 (≈2‐fold increase between day‐1 and day‐14), typical of cells within encapsulated silk hydrogel systems. [ 19,40 ] We assessed the ALP activity (Figure 7Cii) and we noticed that in static groups, the ALP activity increased from day‐1 to day‐14; whereas in actuated, dynamic group ALP activity day‐7 and toned down by day‐14 (≈2.5‐fold increase between dynamic and static group at day‐14). This might be attributed to early onset of mineralization and osteogenic commitment in actuated, dynamic group.…”