Zwitterionic Polymer Brush Coatings for Implant Infection Prevention

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Solution Overview

Problem

Current implant surface modifications fail to effectively prevent biofouling and bacterial infections on metallic implants, leading to periprosthetic infections, as they lack reliable anti-fouling and bactericidal properties, and existing strategies for antibiotic delivery suffer from sub-optimal drug release kinetics and risk of drug resistance.

Innovation Solution

Development of surface coatings with zwitterionic polymer brushes and covalently linked antibacterial moieties, such as vancomycin, using surface-initiated atom transfer radical polymerization (SI-ATRP) and click chemistry to create a dense, tunable antimicrobial surface that prevents biofilm formation and infection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If implant surfaces are modified with conventional coatings, then some level of protection is provided, but the coatings fail to simultaneously achieve effective anti-fouling and bactericidal properties

Engineering Contradiction:
Improveinfection preventionVSAvoidbiofouling and bacterial colonization
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent combines anti-fouling zwitterionic polymer brushes and bactericidal antibiotic moieties into a single integrated surface coating system. The zwitterionic polymer provides anti-fouling properties by preventing protein and bacterial adhesion, while the covalently attached antibiotic moieties provide bactericidal activity, achieving both functions simultaneously in one coating layer.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The coating is constructed as a composite material system consisting of zwitterionic polymer chains (providing anti-fouling) and antibiotic moieties (providing bactericidal activity). This composite structure allows the synergistic combination of different functional materials to address multiple harmful effects simultaneously.

Inventive Principle:
Principle #40Composite materials

2Reliability

If antibiotics are delivered through conventional methods, then bacterial infection is treated, but sub-optimal drug release kinetics and drug resistance occur

Engineering Contradiction:
Improveinfection treatmentVSAvoiddrug release kinetics
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The antibiotic moieties are pre-covalently attached to the polymer chains during the coating formation process, before implantation. This preliminary action ensures that the antibiotics are already in position and properly integrated into the coating matrix, enabling controlled local release at the implant site without requiring subsequent drug delivery steps.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The coating system provides self-service drug delivery through the controlled release of antibiotics from the polymer matrix at the implant site. The local concentration of antibiotics is maintained through the coating's structure, allowing the system to self-regulate drug release kinetics and prevent bacterial resistance without external intervention.

Inventive Principle:
Principle #25Self-service

3Object-affected harmful factors

If surface coatings are designed with high antibiotic density, then bactericidal activity is enhanced, but the complexity of coating synthesis increases

Engineering Contradiction:
Improvebacterial adhesionVSAvoidcoating synthesis
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The coating is designed with segmented functional units: zwitterionic polymer chains for anti-fouling and separately incorporated antibiotic moieties for bactericidal activity. This segmentation allows independent optimization of each function and simplifies the overall synthesis process by enabling modular assembly of the coating components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent utilizes parameter changes in the polymerization process (such as monomer ratio, reaction conditions, and polymerization time) to control the density of antibiotic moieties in the coating. By adjusting these parameters, high antibiotic density can be achieved without requiring complex multi-step synthesis procedures.

Inventive Principle:
Principle #35Parameter changes

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 coatings achieve synergistic anti-fouling and bactericidal properties, reducing the risk of biofilm formation and infection, while providing a controlled and sustained release of antibiotics, thereby minimizing the risk of drug resistance and improving long-term infection prevention.

Implementation Method 1

zwitterionic polymer brushes with zwitterionic and antibiotic-conjugated side chains

Methodology Applied
Scientific EffectElectrostatic interactions: Coulomb's Law

Implementation Method 2

surface polymer brushes are highly modular, allowing independent tuning of the anti-fouling and bactericidal properties

Methodology Applied
Scientific EffectSteric repulsion:

Implementation Method 3

surface-initiated atom transfer radical polymerization (SI-ATRP)

Methodology Applied
Scientific EffectChemical bonding: Chemical Bonding

Implementation Method 4

click chemistry to create a dense, tunable antimicrobial surface

Methodology Applied
Scientific EffectClick chemistry: Chemical Bonding

Data Source

PatentEP2925378B1Multi-functional surface coating of implants
Publication Date: 2019.10.16 UNIV OF MASSACHUSETTS MEDICAL SCHOOL
  • EP2925378B1 patent drawingFigure 1
  • EP2925378B1 patent drawingFigure 2
  • EP2925378B1 patent drawingFigure 3A~3C

AI summary

The invention provides novel surface coatings having surface polymer brushes with zwitterionic and antibiotics-conjugated side chains and synergistic anti-fouling and bactericidal properties. The surface coatings may be prepared using highly efficient surface-initiated "living" polymerization. The design of the surface polymer brushes are highly modular, allowing independent tuning of the anti-fouling and bactericidal properties, e.g., by varying the chemical nature of the zwitterionic motif and the antibiotic agent, the chemistry through which the antibiotic agent is conjugated to the polymer side chains, the molecular weight of the polymer brushes (e.g., thickness of coating and density of respective functional motifs), and the spatial arrangement of the respective functional motifs (e.g., homopolymers, block copolymers, random copolymers) to achieve optimal and sustained anti-infection outcome for a given application.