Fibrin hydrog
els ar
e promising carri
er mat
erials in tissu
e engin
eering. Th
ey ar
e biocompatibl
e and
easy to pr
epar
e, th
ey can bind growth factors and th
ey can b
e pr
epar
ed from a pati
ent’s own blood. Whil
e fibrin structur
e and m
echanics hav
e b
een
ext
ensiv
ely studi
ed, not much is known about th
e r
elation b
etw
een structur
e and diffusivity of solut
es within th
e n
etwork. This is particularly r
el
evant for solut
es with a siz
e similar to that of growth factors. A nov
el m
ethodological approach has b
een us
ed in this study to r
etri
ev
e quantitativ
e structural charact
eristics of fibrin hydrog
els, by combining two compl
em
entary t
echniqu
es, nam
ely confocal fluor
esc
enc
e microscopy with a fib
er
extraction algorithm and turbidity m
easur
em
ents. Bulk rh
eological m
easur
em
ents w
er
e conduct
ed to d
et
ermin
e th
e impact of fibrin hydrog
el structur
e on m
echanical prop
erti
es. From th
es
e m
easur
em
ents it can b
e conclud
ed that variations in th
e fibrin hydrog
el structur
e hav
e a larg
e impact on th
e rh
eological r
espons
e of th
e hydrog
els (up to two ord
ers of magnitud
e diff
er
enc
e in storag
e modulus) but only a mod
erat
e influ
enc
e on th
e diffusivity of d
extran solut
es (up to 25% diff
er
enc
e). By analyzing th
e diffusivity m
easur
em
ents by m
eans of th
e Ogston diffusion mod
el w
e furth
er provid
e evid
enc
e that individual fibrin fib
ers can b
e s
emi-p
erm
eabl
e to solut
e transport, d
ep
ending on th
e av
erag
e distanc
e b
etw
een individual protofibrils. This can b
e important for r
educing mass transport limitations, for modulating fibrinolysis and for growth factor binding, which ar
e all r
el
evant for tissu
e engin
eering.
ec_2">Statement of Significance
Fibrin is a natural biopolymer that has drawn much interest as a biomimetic carrier in tissue engineering applications. We hereby use a novel combined approach for the structural characterization of fibrin networks based on optical microscopy and light scattering methods that can also be applied to other fibrillar hydrogels, like collagen. Furthermore, our findings on the relation between solute transport and fibrin structural properties can lead to the optimized design of fibrin hydrogel constructs for controlled release applications. Finally, we provide new evidence for the fact that fibrin fibers may be permeable for solutes with a molecular weight comparable to that of growth factors. This finding may open new avenues for tailoring mass transport properties of fibrin carriers.