Self-Assembling Monolayer with Poly(ethylene oxide) for Biosensor Immobilization
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Solution Overview
Problem
Current biosensor technologies face challenges in achieving reliable and reproducible immobilization of biomolecules on substrates, particularly due to limitations in self-assembled monolayers that lack poly(ethylene oxide) groups, leading to issues with non-specific adsorption and low yield, which affects the sensitivity and specificity of biosensor interfaces.
Innovation Solution
Development of organic molecules with specific structural formulas that form self-assembling monolayers on metal surfaces, incorporating poly(ethylene oxide) groups and pre-activated functional groups, allowing for direct covalent coupling of biomolecules without additional activation steps, thereby enhancing selectivity, stability, and reproducibility of biosensor substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If self-assembled monolayers are used for biomolecule immobilization, then the immobilization process is simplified, but non-specific adsorption increases and yield decreases
Solution Approach 1:
The patent employs a composite self-assembled monolayer structure combining two distinct molecular components: (1) molecules with terminal carboxylic acid groups that form the base layer on the gold surface, and (2) molecules with pre-formed NHS ester groups that provide the reactive interface for biomolecule coupling. This composite approach allows each component to perform its specialized function, achieving both ease of manufacture and high reliability in immobilization.
Solution Approach 2:
The patent applies preliminary action by pre-forming the NHS ester groups on the monolayer surface before biomolecule introduction. The carboxylic acid groups are first activated to form NHS esters, which are then ready to react with amino groups of biomolecules in a single step. This pre-preparation eliminates the need for on-site activation steps, simplifying the overall process while ensuring high and reproducible immobilization yields.
2Strength
If multiple activation steps are performed after monolayer deposition, then covalent coupling is achieved, but the yield reduces after each step
Solution Approach 1:
The patent merges the activation and coupling steps into a single operational phase. By pre-forming the NHS ester groups on the monolayer, the patent combines what would traditionally be separate steps (activation followed by coupling) into one efficient process where biomolecules are directly coupled to the pre-activated surface, maximizing yield by eliminating intermediate handling and potential loss steps.
Solution Approach 2:
The self-assembled monolayer structure provides self-service by maintaining the reactive NHS ester groups in situ on the surface, ready for immediate reaction with biomolecules. The monolayer acts as a self-contained reactive platform that requires no external activation during the coupling phase, streamlining the process and preserving yield.
3Device complexity
If conventional monolayers without poly(ethylene oxide) groups are used, then the structure is simpler, but non-specific adsorption increases
Solution Approach 1:
The patent applies local quality by incorporating poly(ethylene oxide) groups specifically at the terminal positions of the monolayer molecules, while maintaining the simple thiol-gold anchoring structure at the base. This localized modification provides anti-fouling properties exactly where needed (at the biomolecule interface) without complicating the overall monolayer architecture or the anchoring mechanism to the substrate.
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 proposed solution enables the creation of high-selectivity and high-stability biosensor substrates with reduced non-specific binding, allowing for efficient immobilization of biomolecules in a single step, improving the sensitivity and specificity of biosensor interfaces.
Implementation Method 1
organic molecules suitable for forming a self-assembling monolayer onto a surface, in particular a metal surface
Implementation Method 2
molecules having the formula X—R—Ch-M adhered to a surface as part of a self assembled monolayer
Implementation Method 3
Ch is a chelating agent for the metal ion M
Implementation Method 4
Ch is a chelating agent for the metal ion M
Data Source
AI summary
An article is provided for immobilizing functional organic biomolecules (e.g. proteins, DNA, and the like) through a covalent bond to a thiolate or disulfide monolayer to a metal surface wherein an extra activation step of the surface layer or an activation step of the functional biomolecules or bioreceptors could be avoided. The monolayer can contain, but is not limited to, two moieties. One has a group that resists nonspecific adsorption and another has a group that directly (without activation) reacts with functional groups on the biomolecules. In addition, poly(ethylene oxide) groups are incorporated in the monolayer surfaces to resist the nonspecific adsorption and to enhance the specific affinity interactions. A sensor device including these monolayers is also provided to perform reproducible, sensitive, specific and stable bioanalysis.