Urine Preservative Reagent for Microfiltration Cell Stability
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Solution Overview
Problem
Current methods for preserving urine samples for tumor cell analysis are inadequate, as they often lead to cell lysis, apoptosis, and chemical changes due to temperature fluctuations and bacterial contamination, and existing preservatives are not compatible with microfiltration systems, limiting the recovery and integrity of tumor cells.
Innovation Solution
A preservative reagent comprising polyethylene glycol (PEG), ethanol, paraformaldehyde (PFA), and ethylenediaminetetraacetic acid (EDTA), with pH stabilization, which is added to urine samples to maintain cell stability and integrity for extended storage and transportation, allowing for subsequent microfiltration and analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If methanol and glacial acetic acid are used as preservatives, then cell preservation is improved, but microfilter membrane integrity deteriorates due to dissolution or damage
Solution Approach 1:
The patent changes the chemical parameters of the preservative reagent by using formalin (1-10% v/v) and ethanol (5-20% v/v) instead of methanol and glacial acetic acid. This parameter change maintains cell preservation effectiveness while eliminating the harmful dissolution effect on the microfilter membrane, as formalin and ethanol do not compromise membrane integrity like the original reagents did
Solution Approach 2:
The patent employs a preservative reagent formulation that is safe for the disposable microfilter membrane system. By selecting reagents (formalin and ethanol) that do not damage the membrane, the system allows for single-use disposable filters without requiring complex cleaning or regeneration processes, maintaining both cell preservation and membrane integrity throughout the intended single use cycle
2Reliability
If high concentrations of acid are used as preservatives, then cell stabilization is improved, but safety concerns increase due to hazard material characteristics
Solution Approach 1:
The patent changes the concentration and type of preservative agents by using formalin at 1-10% v/v and ethanol at 5-20% v/v, replacing the need for high concentrations of glacial acetic acid. This parameter change achieves adequate cell stabilization while significantly reducing safety hazards, as these concentrations are much safer to handle than high concentrations of strong acids
Solution Approach 2:
The patent introduces formalin and ethanol as intermediary preservative agents that provide the necessary cell stabilization function without the extreme hazardous properties of concentrated strong acids. These intermediaries achieve the same protective effect on cells but with vastly improved safety profiles for laboratory handling and storage
3Duration of action of stationary object
If urine samples are stored at room temperature or 4°C for prolonged periods, then transportation and storage flexibility is improved, but cell morphology deteriorates due to lysis or apoptosis
Solution Approach 1:
The patent applies preservative reagent (formalin and ethanol) to the urine sample before storage, performing preliminary protection of the cells. This preliminary action prevents cell lysis and apoptosis during the subsequent prolonged storage period at room temperature or 4°C, thereby maintaining cell morphology throughout the extended storage duration
Solution Approach 2:
The preservative reagent components (formalin and ethanol) perform preliminary anti-action against the harmful processes of cell lysis and apoptosis. By introducing these agents before storage, the system pre-empts the morphological degradation that would normally occur during prolonged storage, counteracting the damaging effects before they can compromise cell integrity
4Quantity of substance
If centrifugation is used for cell separation, then cell isolation is achieved, but recovery efficiency deteriorates due to collection of all cell types and particles
Solution Approach 1:
The patent employs a microfilter membrane with specific pore sizes (3-10 micrometers) that selectively allow different cell types to pass through or be retained. This porous structure enables tumor cells (typically larger) to be captured while smaller blood cells and particles pass through, achieving both isolation and high recovery efficiency without the need for centrifugation
Solution Approach 2:
The microfilter membrane provides local quality differentiation across its structure, with specific pore size distributions (3-10 micrometers) that create selective barriers. This local quality allows the filter to differentiate between tumor cells and other cells based on size, capturing tumor cells while allowing smaller cells to pass, thereby achieving high recovery efficiency and selective isolation simultaneously
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 preservative reagent effectively stabilizes tumor cells, preventing decomposition and bacterial growth, enabling reliable microfiltration and downstream analysis, even after prolonged storage or transportation, with high cell recovery and maintenance of cell morphology.
Implementation Method 1
The preservative reagent comprises (i) polyethylene glycol (PEG), (ii) ethanol, (iii) paraformaldehyde (PFA), and (iv) ethylenediaminetetraacetic acid (EDTA)
Implementation Method 2
The CellSieveTM membrane contains a high density of pores with selective sizes, which can separate tumor cells from both blood cells and contaminated particles based on size differences
Implementation Method 3
bacterial contamination and other microorganisms may grow in urine, which may alter microfiltration and downstream analysis
Data Source
AI summary
A preservative reagent for urine is disclosed that increases the stability of cells, such as tumor cells, in urine for a period of several weeks. The preservative reagent comprises polyethylene glycol (PEG), ethanol, paraformaldehyde (PFA), and ethylenediaminetetraacetic acid (EDTA), and optionally pH stabilizing reagents.