Bioprinting
has emerged as a valuable three-dimensional (3D) biomanufacturing
method to fabricate complex hierarchical cell-containing constructs.
Spanning from basic research to clinical translation, sterile starting
materials are crucial. In this study, we present pharmacopeia compendial
sterilization methods for the commonly used bioink component alginate.
Autoclaving (sterilization in saturated steam) and sterile filtration followed by lyophilization
as well as the pharmacopeia noncompendial method, ultraviolet (UV)-irradiation
for disinfection, were assessed. The impact of the sterilization methods
and their effects on physicochemical and rheological properties, bioprinting
outcome, and sterilization efficiency of alginate were detailed. Only
sterile filtration followed by lyophilization as the sterilization
method retained alginate’s physicochemical properties and bioprinting
behavior while resulting in a sterile outcome. This set of methods
provides a blueprint for the analysis of sterilization effects on
the rheological and physicochemical pattern of bioink components and
is easily adjustable for other polymers used in the field of biofabrication
in the future.
Interleukin-4 (IL-4)
is a potentially interesting anti-inflammatory
therapeutic, which is rapidly excreted. Therefore, serum half-life
extension by polymer conjugation is desirable, which may be done by
PEGylation. Here, we use PEtOx as an alternative to PEG for bioconjugate
engineering. We genetically extended murine IL-4 (mIL-4) with the d-domain of insulin-like growth factor I (IGF-I), a previously
identified substrate of transglutaminase (TG) Factor XIIIa (FXIIIa).
Thereby, engineered mIL-4 (mIL-4-TG) became an educt for TG catalyzed
C-terminal, site-directed conjugation. This was deployed to enzymatically
couple an azide group containing peptide sequence to mIL-4, allowing
C-terminal bioconjugation of polyethylene glycol or poly(2-ethyl-2-oxazoline).
Both bioconjugates had wild-type potency and alternatively polarized
macrophages.
The incorporation of photoswitches into the molecular structure of peptides and proteins enables their dynamic photocontrol in complex biological systems. Here, a perfluorinated azobenzene derivative triggered by amber light was site-specifically conjugated to cysteines in a helical peptide by perfluoroarylation chemistry. In response to the photoisomerization (trans!cis) of the conjugated azobenzene with amber light, the secondary structure of the peptide was modulated from a disorganized into an amphiphilic helical structure.
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