Antithrombotic Coatings

Overview of Antithrombotic Coatings：

When foreign materials of medical device come into contact with blood, most of them will adsorb various plasma proteins from the blood, thereby activating the human coagulation system and platelets, and finally forming a thrombus (Figure 1). The thrombus will occlude the device lumen, block the device, even lead to thrombosis and endanger the patient's life.

Figure 1. Schematic diagram of the thrombus formation without any antithrombotic coatings^[1].

Antithrombotic coatings include active antithrombotic and passive antithrombotics.

Active antithrombotics include Heparin, Hirudin, etc., which can be chemically bonded to or released from the coatings. Heparin inhibits the activity of prothrombin, reduces the conversion of prothrombin to thrombin, which in turn reduces platelet activation and aggregation, reduces superficial thrombus formation ultimately (Figure 2). The activity of heparin should be maintained during the bonding process; while a slow and uniform release rate is the key to success of the release type coating. Heparin is currently the only antithrombotic substance approved by the FDA for use in the United States, while hirudin is a synthetic chemical antithrombotic agent with low molecular weight and relatively stable properties. Compared with heparin, it is not only could be used in small doses, but also not cause bleeding, not is dependent on endogenous cofactors.

Figure 2. Effect comparison diagram between uncoated (left) and coated(right)

Passive antithrombotics include amphiphilic ionic materials such as phosphorylcholine (MPC) and betaine (carboxybetaine, phosphobetaine), which mimic the structure of cell membranes and reduce protein adsorption.

There are also some hydrophilic materials, such as polyvinyl alcohol (PEO), which can play the role of hydrophilic anti-fouling and reduce the probability of thrombosis to a certain extent.

Antithrombotic Coatings Applications:

Antithrombotic coatings are especially suitable for consumables that come into contact with blood, including:

Figure 3. Applications examples that usually need antithrombotic coatings

Antithrombotic Coatings Services that CD Bioparticles Can Provide:

Antithrombotic Coatings Development Process

Our antithrombotic coating development process is designed to provide customized coating solutions for medical devices intended for blood-contacting applications. From initial requirement analysis to prototype preparation and performance verification, each stage is tailored to the device characteristics, intended use, and blood-contacting environment.

1. Consultation & Requirements

The process begins with a detailed discussion of the medical device and its intended application. Key parameters include device size and geometry, application conditions and duration, in vivo contact environment, substrate material, Device weight, coating material requirements, and specific blood compatibility objectives. These inputs provide the basis for subsequent coating development and evaluation.

2. Preliminary Research

Based on the defined requirements, the feasibility of the proposed coating strategy is evaluated. Suitable coating materials and surface modification approaches are screened according to their compatibility with the device substrate and intended application. Initial process conditions are also explored to establish a practical development route.

3. Coating Design

A customized coating strategy is developed based on the selected materials and device characteristics. This stage may involve the selection of antithrombotic materials, surface modification strategies, coating structure and thickness design, and optimization of relevant process parameters. The objective is to establish a coating architecture that provides the required antithrombotic performance while maintaining compatibility with the underlying device.

4. Custom Prototyping

Following the initial design, small-batch coating preparation and device-specific process optimization are performed. Prototype devices are coated under defined process conditions to evaluate coating formation and reproducibility. Sterilization-related requirements can also be considered when applicable to the intended application.

5. Performance Testing

The customized coating is evaluated using appropriate in vitro tests to characterize its performance. Testing may include hemocompatibility evaluation, protein adsorption studies, coating stability and durability assessment, surface characterization, and release profile analysis for applicable drug-releasing coatings. These studies help determine whether the coating meets the predefined performance requirements.

6. Optimization & Validation

Based on the testing results, coating formulation and process parameters can be further refined. Performance verification under simulated use conditions, together with reproducibility and batch-to-batch consistency assessment, helps establish a more robust and reliable coating process.

7. Final Coating Solution

After optimization and validation, the finalized antithrombotic coating solution is established for the target medical device. Comprehensive technical data and development support can be provided, with scale-up production available when required. The resulting coating is designed to meet the defined device-specific and blood-contacting requirements.

CD Bioparticles is a world-renowned trusted biotechnology company with a skilled team of scientists and years of experience. We are robust with polymer material synthesis and processing, as well as medical device applications. Please feel free to contact us and our experienced technicians will give you the most detailed answers to your questions.

Reference:
1. Li C. et al., Thrombolytic Agents: Thrombosis-Responsive Thrombolytic Coating Based on Thrombin-Degradable Tissue Plasminogen Activator (t-PA) Nanocapsules. Adv. Funct. Mater. 2017, 27(45), 1703934