Advances in Biomedical Applications of Solution Blow Spinning

Microfluidic-blow-spinning of carvacrol-loaded porphyrin metal - organic framework nanofiber films with synergistic antibacterial capabilities for food packaging

The adherence of foodborne microorganisms threatens human health, necessitating the development of antibacterial food packaging films. In this study, the antibacterial agent carvacrol (CV), hindered by its high volatility and intense aromatic odor, was encapsulated within the photosensitive metal-organic frameworks (MOFs) material PCN-224 (loading rate 50%). Subsequently, the microfluidic-blow-spinning (MBS) technique was employed for the rapid fabrication of CV@PCN-224/polycaprolactone (PCL)/chitosan (CS) nanofiber films. The incorporation of CV@PCN-224 NPs enhances the nanofiber films' thermal stability and mechanical properties and improves the water vapor permeability while maintaining the sustained release of CV over an extended period and good biocompatibility. Due to the simultaneous loading of antibacterial agent (CV) and photosensitive agent (PCN-224), the CV@PCN-224/PCL/CS films exhibited good synergistic antibacterial functionality, as demonstrated by effective inhibition against both E. coli and S. aureus. All results show the vast potential of the prepared nanofiber films in antibacterial food packaging.

Polyurethanes and Their Biomedical Applications

The tunable mechanical properties of polyurethanes (PUs), due to their extensive structural diversity and biocompatibility, have made them promising materials for biomedical applications. Scientists can address PUs' issues with platelet absorption and thrombus formation owing to their modifiable surface. In recent years, PUs have been extensively utilized in biomedical applications because of their chemical stability, biocompatibility, and minimal cytotoxicity. Moreover, addressing challenges related to degradation and recycling has led to a growing focus on the development of biobased polyurethanes as a current focal point. PUs are widely implemented in cardiovascular fields and as implantable materials for internal organs due to their favorable biocompatibility and physicochemical properties. Additionally, they show great potential in bone tissue engineering as injectable grafts or implantable scaffolds. This paper reviews the synthesis methods, physicochemical properties, and degradation pathways of PUs and summarizes recent progress in applying different types of polyurethanes in various biomedical applications, from wound repair to hip replacement. Finally, we discuss the challenges and future directions for the translation of novel polyurethane materials into biomedical applications.

Overexpressed Artificial Spidroin Based Microneedle Spinneret for 3D Air Spinning of Hybrid Spider Silk

Efforts have been devoted to developing strategies for converting spider silk proteins (spidroins) into functional silk materials. However, studies mimicking the exact natural spinning process of spiders encounter arduous challenges. In this paper, consistent with the natural spinning process of spiders, we report a high-efficient spinning strategy that enables the mass preparation of multifunctional artificial spider silk at different scales. By simulating the structural stability mechanism of the cross-β-spine of the amyloid polypeptide by computer dynamics, we designed and obtained an artificial amyloid spidroin with a significantly increased yield (13.5 g/L). Using the obtained artificial amyloid spidroin, we fabricated artificial spiders with artificial spinning glands (hollow MNs). Notably, by combining artificial spiders with 3D printing, we perform patterned air spinning at the macro- and microscales, and the resulting patterned artificial spider silk has excellent pump-free liquid flow and conductive and frictional electrical properties. Based on these findings, we used macroscale artificial spider silk to treat rheumatoid arthritis in mice and micro artificial spider silk to prepare wound dressings for diabetic mice. We believe that artificial spider silk based on an exact spinning strategy will provide a high-efficient way to construct and modulate the next generation of smart materials.

Characterization of Blow-Spun Polyurethane Scaffolds-Influence of Fiber Alignment and Fiber Diameter on Pericyte Growth

In this study, fibrous polyurethane (PU) materials with average fiber diameter of 200, 500, and 1000 nm were produced using a solution blow spinning (SBS) process. The effects of the rotation speed of the collector (in the range of 200-25 000 rpm) on the fiber alignment and diameter were investigated. The results showed that fiber alignment was influenced by the rotation speed of the collector, and such alignment was possible when the fiber diameter was within a specific range. Homogeneously oriented fibers were obtained only for a fiber diameter ≥500 nm. Moreover, the changes in fiber orientation and fiber diameter (resulting from changes in the rotation speed of the collector) were more noticeable for materials with an average fiber diameter of 1000 nm in comparison to 500 nm, which suggests that the larger the fiber diameter, the better the controlled architectures that can be obtained. The porosity of the produced scaffolds was about 65-70%, except for materials with a fiber diameter of 1000 nm and aligned fibers, which had a higher porosity (76%). Thus, the scaffold pore size increased with increasing fiber diameter but decreased with increasing fiber alignment. The mechanical properties of fibrous materials strongly depend on the direction of stretching, whereby the fiber orientation influences the mechanical strength only for materials with a fiber diameter of 1000 nm. Furthermore, the fiber diameter and alignment affected the pericyte growth. Significant differences in cell growth were observed after 7 days of cell culture between materials with a fiber diameter of 1000 nm (cell coverage 96-99%) and those with a fiber diameter of 500 nm (cell coverage 70-90%). By appropriately setting the SBS process parameters, scaffolds can be easily adapted to the cell requirements, which is of great importance in producing complex 3D structures for guided tissue regeneration.

Effect of Collector Rotational Speed on the Morphology and Structure of Solution Blow Spun Polylactic Acid (PLA)

Apart from structure and composition, morphology plays a significant role in influencing the performance of materials in terms of both bulk and surface behavior. In this work, polylactic acid (PLA) constituted by submicrometric fibers is prepared. Using a modified electrospinning (ES) device to carry out solution blow spinning (SBS), the fibrillar morphology is modified, with the aim to induce variations in the properties of the material. The modification of the ES device consists of the incorporation of a source of pressurized gas (air) and a 3D-printed nozzle of our own design. For this work, the morphology of the PLA submicrometric fibers is modified by varying the rotational speed of the collector in order to understand its influence on different properties and, consequently, on the performance of the material. The rotational speed of a cylindrical collector (250, 500, 1000 and 2000 rpm) is considered as variable for changing the morphology. Morphological study of the materials was performed using scanning electron microscopy and image analysis carried out with ImageJ 1.54f software. Besides a morphology study, structural characterization by Fourier transformed infrared spectroscopy using attenuated total reflectance of prepared materials is carried out. Finally, the morphology and structure of produced PLA fibrous mats were correlated with the analysis of mechanical properties, wettability behavior and adhesion of DH5-α E. coli bacteria. It is of interest to highlight how small morphological and chemical structure variations can lead to important changes in materials' performance. These changes include, for example, those above 30% in some mechanical parameters and clear variations in bacterial adhesion capacity.