@misc{9230019,
  abstract     = {{Osteoarthritis is a multifactorial degenerative disease characterized by the breakdown of articular cartilage (AC), affecting hundreds of millions of people worldwide. Among many treatment options, hydrogels have emerged as promising candidates for cartilage replacement, due to their structural resemblance to the native tissue. Hydrogels can be made from various materials, and this study focuses on silk fibroin-based hydrogels, which offer tunable mechanical performance and biocompatibility. 
	Tissue engineering, however, faces a persistent challenge: the trade-off between mechanical stiffness and permeability, as denser structures offer better mechanical properties but poorer fluid transport, which is essential for cartilage function. This study's approach to solving this problem is to develop a hybrid material incorporating levan, a recently characterized fructose-based polysaccharide. It was hypothesized that levan would act as a mesoscale structural modifier, partially decoupling these competing properties in acid-fibrillated silk networks.
	Levan exhibits concentration-dependent self-assembly: below 0.1 mg/mL, it forms fibrils; above this concentration, it forms micelles. A factorial design comprising 30 samples was used to systematically assess the effects of silk concentration (20 and 40 mg/mL), levan concentration (0–1.5 mg/mL), and NaCl concentration (0–150 mM) on mechanical and transport properties. Characterization was performed through fluorescence kinetics (ThT), unconfined compression testing, bioimpedance spectroscopy, drying and rehydrating the samples, and FTIR spectroscopy. In this concentration range, levan showed no significant effect, with silk concentration dominating all measured responses.
A subsequent experiment was performed to explore higher levan concentrations and achieve a 1:1 silk-to-levan ratio. Samples were prepared at 40 mg/mL and 20 mg/mL; the 40 mg/mL preparation encountered several challenges, resulting in imprecise concentrations. The 20 mg/mL samples, in turn, had a smooth preparation and exhibited promising results, especially the 20 mg/mL levan sample, which showed an increase in the swelling ratio and a non-linear improvement in the mechanical moduli, suggesting a critical concentration threshold. 
It is proposed that at high concentrations, levan micelles act as molecular templates, concentrating β-sheet formation around them and generating a more structured porous scaffold. Upon drying and rehydration, levan dissolves, leaving an open-pore network with enhanced fluid-uptake capacity. These findings indicate that levan is not effective as an additive (at low concentrations), but rather as a structural component of the hydrogel when present in sufficient amounts, simultaneously improving mechanical performance and swelling capacity. Further work is required to confirm the micellar template mechanism and optimize composition ratios.}},
  author       = {{de Oliveira Fernandes, Débora}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Effect of Levan on the Mechanical and Transport Properties of Silk–Levan Hydrogels for Tissue Engineering}},
  year         = {{2026}},
}