Abstract:

Electrospun fibers have garnered considerable attention for biomedical  applications due to their unique properties, including high surface area-to volume ratio, tunable mechanical properties, biocompatibility, and controlled  drug release. Electrospinning is a versatile technique for producing fibers at  the nanoscale. It can produce fibers from a wide range of materials, including  synthetic polymers, natural polymers, and blends of both materials.  Measuring the mechanical properties of electrospun fibers is crucial for  understanding their suitability for various biomedical applications. We used a combination of an atomic force microscope and an inverted  optical microscope to investigate the mechanical properties of a single  electrospun nanofiber made of polycaprolactone (PCL) with three different  molecular weights, a blend of PCL and fibrinogen, as well as hydrated PCL  fibers and human fibrinogen. In addition, we determined the mechanical  properties of a fibrous mesh made of human fibrinogen. The findings showed that the molecular weight of PCL has no  significant impact on the mechanical properties of the fiber, as fibers  produced from different molecular weights showed similar mechanical  properties. The mechanical properties of blended fibers were observed to be  influenced by the ratio of fibrinogen to PCL, with extensibility, elastic limit,  and relaxation times increasing as the PCL ratio increased from 25% to 75%. Hydrated PCL fibers were found to have mechanical properties similar to  those of dry single fibers. Interestingly, the extensibility of both dry and  hydrated single human fibrinogen fibers was greater than that of other  electrospun fibers. However, the hydrated fibers were more extensible and  softer than the dry fibers and the fibrous fibrinogen meshes. The study found that stiffness-related mechanical properties, including  the Young's modulus, stress at rupture, and elastic and total moduli, of  electrospun fibers made from different polymers were dependent on fiber  diameter. Specifically, when the fiber diameter decreased below a threshold  between 100-200 nm, the Young's modulus increased several-fold compared  to that of larger diameter fibers. However, when the diameter was larger than  100-200 nm, the modulus remained almost constant. 

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