Dispensing Nozzle PEG Coating Reduces Carry Over
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Solution Overview
Problem
In automatic analyzers, the issue of carry over, where residual components from one sample or reagent contaminate subsequent samples, is exacerbated by the need for trace amounts of biopolymers like proteins, which are difficult to wash off and can lead to increased waste with disposable nozzles.
Innovation Solution
A dispensing nozzle with a chemisorbed polyethylene glycol (PEG) derivative coating on its surface to inhibit nonspecific adsorption of biopolymers, using a covalent bond to attach the PEG derivative, which reduces protein adsorption through steric repulsive forces and maintains surface cleanliness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the diameter of the dispensing nozzle is reduced to dispense trace amounts of samples and reagents, then the sensitivity and cost-effectiveness of analysis is improved, but the surface area to volume ratio increases leading to increased adsorption of substances on the nozzle surface and increased carry over
Solution Approach 1:
The patent changes the chemical parameter of the nozzle surface by coating it with a PEG derivative, transforming the surface properties to reduce adsorption. This allows the nozzle to maintain trace amount dispensing capability while minimizing carry over through chemical modification of the surface characteristics.
Solution Approach 2:
The patent creates a composite structure by combining the nozzle material with a PEG derivative coating layer. This composite surface combines the functional benefits of the base nozzle material with the anti-adsorption properties of the PEG derivative, resolving the contradiction between sensitivity and carry over.
2Ease of operation
If conventional washing methods (pure water or detergent) are used to reduce carry over, then the operation is simple, but biopolymers like protein are difficult to wash off and carry over is not sufficiently reduced
Solution Approach 1:
The patent applies preliminary action by coating the nozzle surface with a PEG derivative before use. This preventive measure eliminates the need for extensive washing operations, as the coating itself prevents adsorption of biopolymers. The simple washing operation becomes sufficient to remove the coating along with any adsorbed substances.
Solution Approach 2:
The PEG derivative coating acts as an intermediary layer between the nozzle surface and the biopolymers. This intermediate layer prevents direct interaction and adsorption between the nozzle surface and protein molecules, making them easy to remove with simple washing while effectively reducing carry over.
3Reliability
If active oxygen is used to deactivate adhering sample residues, then carry over is reduced, but the deactivated residues are deposited on the surface and the nozzle cannot withstand long period use
Solution Approach 1:
The PEG derivative coating acts as a sacrificial, easily replaceable layer that protects the underlying nozzle structure. The coating can be removed and reapplied, allowing the expensive nozzle body to have extended service life while the inexpensive coating handles the chemical degradation from cleaning processes.
4Reliability
If a disposable nozzle is used to solve carry over, then contamination between samples is eliminated, but a large amount of waste is produced increasing environmental load
Solution Approach 1:
Instead of discarding the entire nozzle, the patent allows for recovery and reuse of the nozzle body while the PEG derivative coating is discarded and reapplied. This selective discarding approach eliminates carry over while minimizing waste, as the expensive nozzle structure is preserved and only the inexpensive coating is replaced.
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
Significantly reduces carry over during dispensing operations, enhancing analysis reliability and reducing costs by minimizing the use of precious samples and reagents while minimizing environmental impact.
Implementation Method 1
the PEG derivative, which reduces protein adsorption through steric repulsive forces
Implementation Method 2
the PEG derivative, which reduces protein adsorption
Implementation Method 3
A dispensing nozzle with a chemisorbed polyethylene glycol (PEG) derivative coating on its surface to inhibit nonspecific adsorption of biopolymers, using a covalent bond to attach the PEG derivative
Data Source
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AI summary
An automatic analyzer for analyzing samples, such as urine and blood, is adapted so that analysis measured values are not affected by carry over by a repeatedly used dispensing nozzle. Coating the surface of the dispensing nozzle with a chemisorbed polyethylene glycol derivative forms a molecular layer that inhibits the adsorption of biopolymers, to reduce carry over by the dispensing nozzle.