Double cross-linked interpenetrating polymer network (IPN) hydrogels of sodium alginate and gelatin (SA/G) reinforced with 50 wt % cellulose nanocrystals (CNC) have been prepared via the freeze-drying process. The IPNs were designed to incorporate CNC with carboxyl surface groups as a part of the network contribute to the structural integrity and mechanical stability of the hydrogel. Structural morphology studies of the hydrogels showed a three-dimensional (3D) network of interconnected pores with diameters in the range of 10-192 μm and hierarchical pores with a nanostructured pore wall roughness, which has potential benefits for cell adhesion. Significant improvements in the tensile strength and strain were achieved in 98% RH at 37 °C for CNC cross-linked IPNs. The high porosity of the scaffolds (>93%), high phosphate buffered saline (PBS) uptake, and cytocompatibility toward mesenchymal stem cells (MSCs) are confirmed and considered beneficial for use as a substitute for cartilage.

Fully bio-based 3-dimensional porous scaffolds based on freeze-dried cellulose nanofibers (70-90 wt%) stabilized using a genipin crosslinked matrix of gelatin and chitosan were prepared. Morphology studies using scanning electron microscopy showed that the scaffolds have interconnected pores with average pore diameters of 75-200 mm and nanoscaled pore wall roughness, both favorable for cell interactions with cartilage repair. X-ray tomography confirmed the 3-dimensional homogeneity and interconnectivity of the pores as well as the fibrillar structure of the scaffolds. The compression modulus of the scaffolds (1-3 MPa) at room conditions was higher than natural cartilage (z1 MPa). The lowered compression modulus of 10-60 kPa in phosphate buffered saline (PBS) at 37 C was considered favorable for chondrogenesis. The current study therefore successfully addressed the challenge of tailoring the pore structure and mechanical properties simultaneously for cartilage regeneration. Furthermore, the scaffolds' high porosity (z95%), high PBS uptake and good cytocompatibility towards chondrocytes are considered beneficial for cell attachment and extracellular matrix (ECM) production.

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Randomly oriented fiber mats of chitosanpolyethylene oxide matrix reinforced with cellulose nanocrystals (CNCs) were prepared by electrospinning technique. The cellulose nanocrystals used were isolated using hydrochloric acid (CNC HCl ) or sulphuric acid (CNC H 2 SO 4 ) and the concentration of CNCs was 50 wt% in the electrospun mats. The surface characteristics of the nanocrystals were found to affect the dispersion, viscosity, conductivity and zetapotential of the respective spinning solutions and resulted in better spinnability, homogeneity as well as crosslinking of CNC HCl based nanocomposite fiber mats compared to CNC H 2 SO 4 ones. The microscopy studies showed that the diameter of the electrospun fibers decreased with the inclusion of both types of nanocrystals and that crosslinking decreased the porosity of the mats. The tensile strength and tensile modulus of the mats increased with the addition of nanocrystals and increased further for the CNC HCl based mats (58 MPa, 3.1 GPa) after crosslinking. The as-spun CNC HCl based mats had average pore diameters of 1.6 lm and porosity of 38 %. The water vapor permeability and the O 2 /CO 2 transmission increased with the addition of CNC HCl . The used nanocrystals as well as electrospun mats showed noncytotoxic impact on adipose derived stem cells (ASCs), which was considered favorable for wound dressing.

We previously identified a decapeptide from the model plant Arabidopsis thaliana, OSIP108, which is induced upon fungal pathogen infection. In this study, we demonstrated that OSIP108 interferes with biofilm formation of the fungal pathogen Candida albicans without affecting the viability or growth of C. albicans cells. OSIP108 displayed no cytotoxicity against various human cell lines. Furthermore, OSIP108 enhanced the activity of the antifungal agents amphotericin B and caspofungin in vitro and in vivo in a Caenorhabditis elegans-C. albicans biofilm infection model. These data point to the potential use of OSIP108 in combination therapy with conventional antifungal agents. In a first attempt to unravel its mode of action, we screened a library of 137 homozygous C. albicans mutants, affected in genes encoding cell wall proteins or transcription factors important for biofilm formation, for altered OSIP108 sensitivity. We identified 9 OSIP108-tolerant C. albicans mutants that were defective in either components important for cell wall integrity or the yeast-to-hypha transition. In line with these findings, we demonstrated that OSIP108 activates the C. albicans cell wall integrity pathway and that its antibiofilm activity can be blocked by compounds inhibiting the yeast-to-hypha transition. Furthermore, we found that OSIP108 is predominantly localized at the C. albicans cell surface. These data point to interference of OSIP108 with cell wall-related processes of C. albicans, resulting in impaired biofilm formation.