Visible-Light Spider Silk Bioink for Cell-Safe 3D Hydrogel Printing
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Solution Overview
Problem
Conventional bio-inks, such as collagen and alginate, require ultraviolet (UV) light for effective crosslinking, which can damage cells and have limited penetration depth, making them unsuitable for sensitive biological applications.
Innovation Solution
A photocrosslinkable bioink composition using a recombinant spider silk protein, visible light-reactive polymers, and photoinitiators like tris(bipyridine)ruthenium(II) chloride with ammonium persulfate, eosin Y with triethanolamine, or riboflavin with ammonium persulfate, allowing crosslinking under visible light to form biocompatible hydrogels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UV light is used for crosslinking conventional bio-inks (collagen, alginate), then crosslinking effectiveness is improved, but cell viability deteriorates due to cytotoxicity and limited penetration depth
Solution Approach 1:
The patent changes the wavelength parameter of the curing light from UV range to visible light range (405-520 nm). This parameter change allows the use of photoinitiators that activate under visible light, thereby eliminating UV-induced cytotoxicity while maintaining effective crosslinking of the bioink composition containing spider silk protein and photopolymerizable monomers.
Solution Approach 2:
The patent introduces visible light photoinitiators (such as tris(bipyridine)ruthenium(II) chloride, eosin Y, riboflavin, or lithium phenyl-2,4,6-trimethylbenzoylphosphinate) as intermediary substances that mediate the crosslinking process. These photoinitiators absorb visible light and generate reactive species that initiate polymerization without requiring direct UV exposure, thus protecting cells from UV damage while achieving effective crosslinking.
2Reliability
If UV light is used for crosslinking, then crosslinking effectiveness is improved, but light penetration depth deteriorates in biological tissues
Solution Approach 1:
The patent changes the light wavelength parameter from UV to visible range (405-520 nm). Visible light has longer wavelength and lower energy than UV light, enabling deeper penetration through biological tissues and hydrogel matrices while still providing sufficient energy to activate the photoinitiators for effective crosslinking.
3Reliability
If UV light is used for crosslinking, then crosslinking effectiveness is improved, but harmful factors generated deteriorate (reactive oxygen species damaging nucleic acids and proteins)
Solution Approach 1:
The patent employs visible light photoinitiators as intermediary substances that generate reactive species only upon absorption of visible light. These photoinitiators (such as tris(bipyridine)ruthenium(II) chloride, eosin Y, riboflavin, or lithium phenyl-2,4,6-trimethylbenzoylphosphinate) mediate the crosslinking process without generating the harmful reactive oxygen species that UV light produces, thereby eliminating damage to nucleic acids and proteins while maintaining effective crosslinking.
Solution Approach 2:
The patent converts the potential harm of requiring high-energy UV light for crosslinking into a benefit by using visible light photoinitiators. The visible light photoinitiators capture the energy from visible light (which is safer for cells) and convert it into the reactive species needed for crosslinking, thereby eliminating the harmful UV radiation while maintaining the necessary crosslinking effectiveness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The bioink composition supports cell adhesion and proliferation with enhanced printability and structural fidelity, providing a safer and more compatible environment for cell-laden constructs.
Implementation Method 1
a polymer comprising pendant groups reactive under visible light-initiated radical polymerization; and a photoinitiator system configured to generate free radicals upon exposure to visible light
Data Source
AI summary
A photocrosslinkable bioink composition for three-dimensional printing is provided. The photocrosslinkable bioink composition includes: an aqueous solution of a recombinant spider silk protein comprising the NT2RepCT-MaSp2 sequence; a polymer comprising pendant groups reactive under visible light-initiated radical polymerization; and a photoinitiator system configured to generate free radicals upon exposure to visible light. The polymer is selected from the group consisting of methacrylated gelatin, methacrylated hyaluronic acid, methacrylated chitosan, polyethylene glycol diacrylate, and combinations thereof. The photoinitiator system is selected from the group consisting of tris(bipyridine)ruthenium(II) chloride with ammonium persulfate, eosin Y with triethanolamine, riboflavin with ammonium persulfate, and lithium phenyl-2,4,6-trimethylbenzoylphosphinate. The photocrosslinkable bioink composition is curable under visible light to form a biocompatible hydrogel structure suitable for cell culture or implantation.