High-Resolution Bioprinting of Recombinant Human Collagen Type III

The development of commercial collagen inks for extrusion-based bioprinting has increased the amount of research on pure collagen bioprinting, i.e., collagen inks not mixed with gelatin, alginate, or other more common biomaterial inks. New printing techniques have also improved the resolution achievable with pure collagen bioprinting. However, the resultant collagen constructs still appear too weak to replicate dense collagenous tissues, such as the cornea. This work aims to demonstrate the first reported case of bioprinted recombinant collagen films with suitable optical and mechanical properties for corneal tissue engineering. The printing technology used, aerosol jet® printing (AJP), is a high-resolution printing method normally used to deposit conductive inks for electronic printing. In this work, AJP was employed to deposit recombinant human collagen type III (RHCIII) in overlapping continuous lines of 60 µm to form thin layers. Layers were repeated up to 764 times to result in a construct that was considered a few hundred microns thick when swollen. Samples were subsequently neutralised and crosslinked using EDC:NHS crosslinking. Nanoindentation and absorbance measurements were conducted, and the results show that the AJP-deposited RHCIII samples possess suitable mechanical and optical properties for corneal tissue engineering: an average effective elastic modulus of 506 ± 173 kPa and transparency ≥87% at all visible wavelengths. Circular dichroism showed that there was some loss of helicity of the collagen due to aerosolisation. SDS-PAGE and pepsin digestion were used to show that while some collagen is degraded due to aerosolisation, it remains an inaccessible substrate for pepsin cleavage.

Collagen-Based Materials Modified by Phenolic Acids—A Review

Collagen-based biomaterials constitute one of the most widely studied types of materials for biomedical applications. Low thermal and mechanical parameters are the main disadvantages of such structures. Moreover, they present low stability in the case of degradation by collagenase. To improve the properties of collagen-based materials, different types of cross-linkers have been researched. In recent years, phenolic acids have been studied as collagen modifiers. Mainly, tannic acid has been tested for collagen modification as it interacts with a polymeric chain by strong hydrogen bonds. When compared to pure collagen, such complexes show both antimicrobial activity and improved physicochemical properties. Less research reporting on other phenolic acids has been published. This review is a summary of the present knowledge about phenolic acids (e.g., tannic, ferulic, gallic, and caffeic acid) application as collagen cross-linkers. The studies concerning collagen-based materials with phenolic acids are summarized and discussed.

Collagen as Bioink for Bioprinting: A Comprehensive Review.

Biomaterials made using collagen are successfully used as a three-dimensional (3D) substrate for cell culture and considered to be promising scaffolds for creating artificial tissues. An important task that arises for engineering such materials is the simulation of physical and morphological properties of tissues, which must be restored or replaced. Modern additive technologies, including 3D bioprinting, can be applied to successfully solve this task. This review provides the latest evidence on advances of 3D bioprinting with collagen in the field of tissue engineering. It contains modern approaches for printing pure collagen bioinks consisting only of collagen and cells, as well as the obtained results from the use of pure collagen bioinks in different fields of tissue engineering.

A Parameter Study for 3D-Printing Organized Nanofibrous Collagen Scaffolds Using Direct-Write Electrospinning

Collagen-based scaffolds are gaining more prominence in the field of tissue engineering. However, readily available collagen scaffolds either lack the rigid structure (hydrogels) and/or the organization (biopapers) seen in many organ tissues, such as the cornea and meniscus. Direct-write electrospinning is a promising potential additive manufacturing technique for constructing highly ordered fibrous scaffolds for tissue engineering and foundational studies in cellular behavior, but requires specific process parameters (voltage, relative humidity, solvent) in order to produce organized structures depending on the polymer chosen. To date, no work has been done to optimize direct-write electrospinning parameters for use with pure collagen. In this work, a custom electrospinning 3D printer was constructed to derive optimal direct write electrospinning parameters (voltage, relative humidity and acetic acid concentrations) for pure collagen. A LabVIEW program was built to automate control of the print stage. Relative humidity and electrospinning current were monitored in real-time to determine the impact on fiber morphology. Fiber orientation was analyzed via a newly defined parameter (spin quality ratio (SQR)). Finally, tensile tests were performed on electrospun fibrous mats as a proof of concept.

Collagen Sources and Areas of Use

Fibrillar collagen type I undenatured represent the major structural component of all organs and connective tissues, which due to low antigenicity and outstanding biocompatibility the possibility of controlling the time of biodegradation by crosslinking, the ease of forming composites with other natural polymers and synthetic, represents one of the most used natural biomaterials . Collagen biomaterials are successfully used in gene therapy for artificial implants. They are used as medical devices, scaffolds for tissue regeneration, supports for drug release. Collagen can be extracted from various sources considering that it is one of the most abundant proteins on earth. It can be extracted from almost every living animal, even including alligators and kangaroos. Nonetheless, common sources of collagen for tissue engineering applications include bovine skin and tendons, porcine skin and rat tail among others. Marine life forms are also a considerable source of collagen, which can be extracted from sponges, fish and jellyfish. These collagens are widely used in the industry, but less for research and clinical usage. All these collagen sources are worth investigating considering that collagen properties differ from one animal to another. Collagen can also be used in biomedical applications as a decellularized ECM serving as a scaffolding material for tissue regeneration. Although extractible from many different sources, the diversity of acellular. Due to these features and the possibility to be isolated in pure collagen, they are essential in areas such as medicine, cosmetics, food and pharmaceutical applications.

Collagen Sources and Areas of Use

Fibrillar collagen type I undenatured represent the major structural component of all organs and connective tissues, which due to low antigenicity and outstanding biocompatibility the possibility of controlling the time of biodegradation by crosslinking, the ease of forming composites with other natural polymers and synthetic, represents one of the most used natural biomaterials . Collagen biomaterials are successfully used in gene therapy for artificial implants. They are used as medical devices, scaffolds for tissue regeneration, supports for drug release. Collagen can be extracted from various sources considering that it is one of the most abundant proteins on earth. It can be extracted from almost every living animal, even including alligators and kangaroos. Nonetheless, common sources of collagen for tissue engineering applications include bovine skin and tendons, porcine skin and rat tail among others. Marine life forms are also a considerable source of collagen, which can be extracted from sponges, fish and jellyfish. These collagens are widely used in the industry, but less for research and clinical usage. All these collagen sources are worth investigating considering that collagen properties differ from one animal to another. Collagen can also be used in biomedical applications as a decellularized ECM serving as a scaffolding material for tissue regeneration. Although extractible from many different sources, the diversity of acellular. Due to these features and the possibility to be isolated in pure collagen, they are essential in areas such as medicine, cosmetics, food and pharmaceutical applications.