Development and Characterization of Heparin-Containing Hydrogel/3D-Printed Scaffold Composites for Craniofacial Reconstruction.

Regeneration of cartilage and bone tissues remains challenging in tissue engineering due to their complex structures, and the need for both mechanical support and delivery of biological repair stimuli. Therefore, the goal of this study was to develop a composite scaffold platform for anatomic chondral and osteochondral repair using heparin-based hydrogels to deliver small molecules within 3D-printed porous scaffolds that provide structure, stiffness, and controlled biologic delivery. We designed a mold-injection system to combine hydrolytically degradable hydrogels and 3D-printed scaffolds that could be employed rapidly (< 30 min) in operating room settings (~23 °C). Micro-CT analysis demonstrated the effectiveness of our injection system through homogeneously distributed hydrogel within the pores of the scaffolds. Hydrogels and composite scaffolds exhibited efficient loading (~94%) of a small positively charged heparin-binding molecule (crystal violet) with sustained release over 14 days and showed high viability of encapsulated porcine chondrocytes over 7 days. Compression testing demonstrated nonlinear viscoelastic behavior where tangent stiffness decreased with scaffold porosity (porous scaffold tangent stiffness: 70%: 4.9 MPa, 80%: 1.5 MPa, and 90%: 0.20 MPa) but relaxation was not affected. Lower-porosity scaffolds (70%) showed stiffness similar to lower ranges of trabecular bone (4-8 MPa) while higher-porosity scaffolds (80% and 90%) showed stiffness similar to auricular cartilage (0.16-2 MPa). Ultimately, this rapid composite scaffold fabrication method may be employed in the operating room and utilized to control biologic delivery within load-bearing scaffolds.

Multipronged Approach to Combat Catheter-Associated Infections and Thrombosis by Combining Nitric Oxide and a Polyzwitterion: a 7 Day In Vivo Study in a Rabbit Model.

The development of nonfouling and antimicrobial materials has shown great promise for reducing thrombosis and infection associated with medical devices with aims of improving device safety and decreasing the frequency of antibiotic administration. Here, the design of an antimicrobial, anti-inflammatory, and antithrombotic vascular catheter is assessed in vivo over 7 d in a rabbit model. Antimicrobial and antithrombotic activity is achieved through the integration of a nitric oxide donor, while the nonfouling surface is achieved using a covalently bound phosphorylcholine-based polyzwitterionic copolymer topcoat. The effect of sterilization on the nonfouling nature and nitric oxide release is presented. The catheters reduced viability of Staphylococcus aureus in long-term studies (7 d in a CDC bioreactor) and inflammation in the 7 d rabbit model. Overall, this approach provides a robust method for decreasing thrombosis, inflammation, and infections associated with vascular catheters.

Silylation of bacterial cellulose to design membranes with intrinsic anti-bacterial properties.

In this work, we report a convenient method of grafting non-leachable bioactive amine functions onto the surface of bacterial cellulose (BC) nanofibrils, via a simple silylation treatment in water. Two different silylation protocols, involving different solvents and post-treatments were envisaged and compared, using 3-aminopropyl-trimethoxysilane (APS) and (2-aminoethyl)-3-aminopropyl-trimethoxysilane (AEAPS) as silylating agents. In aqueous and controlled conditions, water-leaching resistant amino functions could be successfully introduced into BC, via a simple freeze-drying process. The silylated material remained highly porous, hygroscopic and displayed sufficient thermal stability to support the sterilization treatments generally required in medical applications. The impact of the silylation treatment on the intrinsic anti-bacterial properties of BC was investigated against the growth of Escherichia coli and Staphylococcus aureus. The results obtained after the in vitro studies revealed a significant growth reduction of S. aureus within the material.

Functional properties of bicarbonates and lactic acid on chicken breast retail display properties and cooked meat quality.

Whole chicken breast was injected with potassium bicarbonate (PB), sodium bicarbonate (SB), and potassium lactate (K-lactate) and salt, alone or in combination at different concentration levels. The objectives were to 1) investigate the effects of different concentration of PB, SB, and PL on instrumental color, water-holding capacity (WHC), objective tenderness, expressible moisture, and moisture content and 2) evaluate whether sodium-containing ingredients can be replaced with potassium as a potential strategy to reduce total sodium content in the finished product. Results showed that chicken breast tissue marinated with SB and PB had greater moisture retention, display characteristics, and cooked product qualities than chicken breast tissue injected with water and the nonmarinated control. The L* values (lightness) did not change over the period of retail display and were not different compared to the control (P>0.05). The chicken breast enhanced with SB, PB, and K-lactate retained better retail display color than the controls (marinated with water and nonmarinated). Increasing the potassium bicarbonate concentration from 0.5 to 1.5% significantly improved the water-holding capacity (82.17 to 92.61%; P<0.05) and led to better cook yield (83.84 to 91.96%). Shear force values were lower at the 0.5% level for both SB and PB compared to the control. PB performed better on retail display and cooked meat quality than SB. This study suggests that chicken breast tissue can be marinated with KB as a healthier alternative to phosphate or SB.