MECHANICAL PROPERTIES OF SINGLE ELECTROSPUN NANOFIBERS FOR BIOMEDICAL APPLICATIONS

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.