3D Printed UV Masks for Spatial Heparin Release Control
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Solution Overview
Problem
Current vascular graft technologies fail to effectively prevent thrombosis due to physiological differences along the graft, particularly at the distal anastomosis, and existing methods for antithrombotic coatings have limitations such as short-term drug release, harsh solvents, and negative effects on endothelial cells.
Innovation Solution
An interlayer system using 3D printed masks for controlled UV crosslinking of gelatin methacrylate (gelMA) within a decellularized bovine pericardium and poly(propylene fumarate) biohybrid vascular graft, allowing for spatial and temporal modulation of heparin release to create a sustained antithrombotic environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If eluting surface treatments are used for drug delivery, then short-term burst release of heparin is achieved, but most of the bioactive molecule is washed away and release duration is limited
Solution Approach 1:
Heparin is pre-loaded into gelMA interlayers during the manufacturing process, allowing the drug to be retained and released sustainably over time rather than washing away immediately. The gelMA matrix is prepared in advance with drug encapsulation capabilities
Solution Approach 2:
The gelMA interlayer acts as an intermediary carrier between the heparin drug and the external environment. It controls the release kinetics by mediating the interaction between the drug and surrounding fluids, enabling sustained release profiles
2Manufacturing precision
If non-eluting surface treatments are used, then localized delivery is provided, but treatment techniques can alter graft properties and cell viability may be compromised
Solution Approach 1:
The degree of UV crosslinking is precisely controlled by adjusting mask patterns and exposure parameters, allowing optimization of gelMA network density to balance drug retention with maintenance of graft mechanical properties and cell viability. Crosslinking density is tuned to achieve desired release kinetics without compromising functionality
3Stability of the object's composition
If uniform UV crosslinking is applied to gelMA, then complete polymerization is achieved, but controlled spatial release profiles cannot be obtained
Solution Approach 1:
Different regions of the gelMA interlayer are crosslinked to different degrees by using patterned masks during UV exposure. This creates spatially varying drug release profiles where certain areas release heparin faster than others, enabling zone-specific therapeutic effects
Solution Approach 2:
The gelMA interlayer is divided into multiple regions with distinct crosslinking densities through patterned UV exposure. Each segment has tailored release characteristics, allowing complex spatiotemporal release profiles to be achieved by combining multiple segmented zones
4Duration of action of moving object
If microparticle encapsulation or electrospun fibers are used, then extended drug release is achieved, but harsh solvents impair loading efficiency, release kinetics, and bioactivity
Solution Approach 1:
The gelMA interlayer uses a biocompatible, water-based hydrogel matrix instead of systems requiring harsh organic solvents. This disposable-like approach prioritizes bioactivity preservation and loading efficiency over long-term structural permanence, achieving sustained release through controlled degradation and diffusion
Solution Approach 2:
The system combines gelMA hydrogel with heparin to create a composite interlayer material. The gelMA provides a biocompatible matrix that maintains heparin bioactivity while enabling controlled release, avoiding the need for solvent-based encapsulation systems
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
This approach provides a long-term, sustained release of heparin that balances endothelialization with thrombotic response, reducing thrombosis risk and maintaining graft functionality, while being compatible with off-the-shelf production.
Implementation Method 1
gelatin methacrylate (gelMA) has been employed to achieve long-term sustained drug release without solvents and its properties can be influenced through UV crosslinking
Data Source
AI summary
Current approaches in small diameter vascular grafts for coronary artery bypass surgeries fail to address physiological variations along the graft that contribute to thrombus formation and ultimately graft failure. An interlayer drug delivery system can sustain delivery of heparin through the graft with a high degree of temporal and spatial control. A heparin-loaded gelatin methacrylate interlayer sits between a biohybrid composed of decellularized bovine pericardium and poly(propylene fumarate) and UV crosslinking is controlled via 3D printed shadow masks. The masks enable control of the resultant gelMA crosslinking and properties by modulating the incident light intensity on the graft. High doses of heparin have detrimental effects on endothelial cell function. When exposed to heparin in a slower, more sustained manner consistent with the masks, endothelial cells behave similarly to untreated cells. Slower release profiles cause significantly more release of tissue factor pathway inhibitor, an anticoagulant, than a faster release profile.