Using the Langmuir-Blodgett (LB) technology we have pioneered a straightforward and low-cost approach to fabricate highly oriented collagen in thin film format (thickness: ~20 nm, surface areas: 2.5 x ~6.0 cm). An important factor for the use of these films is their cohesion under various conditions. Film formation was studied by coating hydrophilic or hydrophobic glass substrates. The fresh or aged (2 ½ years,-18°C.) collagen solutions used for this purpose either contained collagen network-stabilizing agents (n-propanol or phosphate ions) or were prepared without these stabilizers. Film formation on the air/water interface was analyzed by pressure-area isotherms. Maximum surface pressures were ~ 4-7 mN/m and ~ 10-18 mN/m for isotherms using n-propanol or phosphate buffer saline (PBS), respectively, versus ~ 0.4-0.8 mN/m without using a stabilizer; with higher surface pressures for the combination fresh solution/n-propanol or aged solution/PBS. Deposited films were studied by optical and electron microscopy and fast Fourier transform analysis. Coatings (to both substrate types) exhibit a defined orientation of collagen aggregates within a matrix of oriented collagen when freshly made or aged collagen solutions were used and n-propanol was present during film formation. The higher degree of hydrophilicity of the aged solution does not adversely affect the cohesion and collagen orientation during film formation. Using physiological phosphate ions shows that deposition of defect-free and oriented collagen (on both substrate types) is only possible using fresh collagen solutions. Unlike n-propanol-containing solutions, films were most stable using hydrophilic glass substrates. Film formation failed in the absence of network stabilizers. Controlling the cohesion via (a) the water accessibility of collagen structures, (b) specific network stabilizers and (c) substrate properties enables tunable film characteristics for future biomedical approaches.

Collagen is the most abundant protein in the human body and serves many functions, from mechanical stability and elasticity in tendons and bone, to optical properties, such as transparency and a fine tuned refractive index in the cornea of the eye. Collagen has interested humankind for centuries: Leonardo Da Vinci studied and drew the tendons in the human body precisely in the 15th and 16th century. A look at the literature reveals easily > 200,000 papers. This article reviews oriented type I collagen artificial alignment strategies.

As a pre-study for highly oriented collagen coatings on implants (with irregular surfaces and shapes), the Langmuir-Blodgett (LB) technology, a low-cost and straightforward approach, was pioneered. The effects of physicochemical (hydrophilic / hydrophobic) patterns and 3Dmechanical barriers present on substrate surfaces are studied in terms of the dynamics of collagen flow during LB film deposition and the formation of highly oriented coatings. Due to the large internal cohesion of collagen films only large 3D-obstacles deflect the flow of collagen and lead to film rupture, suggesting that objects (screw-threaded dental implants) with small topographic features should be easily and evenly coatable. Moreover, hydrophilic / hydrophobic / collagen patterned substrate surfaces were fabricated, by partly removing coated collagen. These substrates are outstanding for timely studies that need identical conditions but different surface properties side by side. Crystallization of barium oxalate was carried out as a proof-of-principle.3

As a pre-study for highly oriented collagen coatings on implants (with irregular surfaces and shapes), the Langmuir-Blodgett (LB) technology, a low-cost and straightforward approach, was pioneered. The effects of physicochemical (hydrophilic/hydrophobic) patterns and 3D-mechanical barriers present on substrate surfaces are studied in terms of the dynamics of collagen flow during LB film deposition and the formation of highly oriented coatings. Due to the large internal cohesion of collagen films, only large 3D-obstacles deflect the flow of collagen and lead to film rupture, suggesting that objects (screw-threaded dental implants) with small topographic features should be easily and evenly coatable. Moreover, hydrophilic/hydrophobic/collagen patterned substrate surfaces were fabricated, by partly removing coated collagen. These substrates are outstanding for timely studies that need identical conditions but different surface properties side by side. Crystallisation of barium oxalate was carried out as a proof-of-principle.