Effect of iron oxide nanoparticles on fibrin gel formation and its fractal dimension

Technological advances in fibrin for tissue engineering

Fibrin is a promising natural polymer that is widely used for diverse applications, such as hemostatic glue, carrier for drug and cell delivery, and matrix for tissue engineering. Despite the significant advances in the use of fibrin for bioengineering and biomedical applications, some of its characteristics must be improved for suitability for general use. For example, fibrin hydrogels tend to shrink and degrade quickly after polymerization, particularly when they contain embedded cells. In addition, their poor mechanical properties and batch-to-batch variability affect their handling, long-term stability, standardization, and reliability. One of the most widely used approaches to improve their properties has been modification of the structure and composition of fibrin hydrogels. In this review, recent advances in composite fibrin scaffolds, chemically modified fibrin hydrogels, interpenetrated polymer network (IPN) hydrogels composed of fibrin and other synthetic or natural polymers are critically reviewed, focusing on their use for tissue engineering.

Structure and refractive index of fibrin protofibril aggregates according to laser phase microscopy accompanied by DLS and AFM

The structures, sizes, and refractive indices (RI) of protein aggregates formed in a fibrinogen-thrombin system are examined using laser phase microscopy (LPM) accompanied by dynamic light scattering (DLS) and atomic force microscopy (AFM) measurements. Fibrin aggregates found in pure fibrinogen and fibrinogen with thrombin solutions by the DLS method, after drying the sample, form complex structures of different shapes and sizes on a glass surface. The LPM reveals submicron-sized dimeric structures in the pure fibrinogen solution, elongated micron-length structures, and rectangular structures in the fibrinogen-thrombin sample. AFM measurements show that the elongated structures form branched fibers, which in turn assembly into rectangular structures. All sizes obtained by LPM and AFM are consistent with DLS measurements. The refractive indices of all the structures, estimated by optical thickness, vary from 1.53 to 1.62, which indicates that they are fibrinogen derivatives. Effective visualization of the structure and determination of the optical properties for fibrin gel indicate that laser phase microscopy is capable of tissue imaging and characterization.