Nucleic Acid Biosensor Thermal Cycling for Reliable Detection

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Solution Overview

Problem

Nucleic acid biosensors face challenges in accurately detecting target molecules due to non-specific interactions, temperature fluctuations, and sensitivity to environmental conditions, which affect the reliability and precision of measurements, especially in liquid environments where real-time monitoring is required.

Innovation Solution

A method utilizing self-assembled monolayers of nucleic acids with extraordinary thermal properties, where temperature cycles are used to produce changes in mechanical features of the biosensor, allowing for high sensitivity detection of target molecules without melting, and combining temperature and relative humidity variations to enhance sensitivity and reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If temperature control is used to remove non-specific interactions and detach non-target molecules, then detection reliability is improved, but measurement precision deteriorates due to temperature fluctuations affecting the biosensor

Engineering Contradiction:
Improvedetection reliabilityVSAvoidmeasurement precision
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies parameter changes by utilizing temperature cycles to modify the physical state of the nucleic acid layers. By heating to temperatures below the melting temperature, non-specific interactions are removed while preserving target binding. The cyclic temperature variation allows repeated measurements without permanent damage to the biosensor structure.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements periodic action through temperature cycling - repeatedly heating and cooling the biosensor. This periodic thermal treatment enables multiple detection cycles, where each cycle removes non-specific bindings and restores the sensor to its initial state, allowing continuous monitoring without permanent degradation.

Inventive Principle:
Principle #19Periodic action

2Measurement precision

If fluorescence microscopy with pre-treatment with fluorescent dyes is used for detection, then measurement precision is improved, but device complexity and time consumption increase

Engineering Contradiction:
Improvedetection precisionVSAvoiddetection system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the optical detection system (fluorescence microscopy) with a mechanical detection system based on microcantilever deflection. The bending of the cantilever caused by nucleic acid hybridization provides a direct mechanical signal that can be detected without complex optical equipment, fluorescent dyes, or extensive sample preparation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and eliminates the need for fluorescent markers and complex optical detection systems. By using the inherent mechanical properties of the microcantilever and the mass change from nucleic acid binding, the system achieves detection without the additional components and preparation steps required by fluorescence microscopy.

Inventive Principle:
Principle #2Taking out (Extraction)

3Productivity

If real-time monitoring in liquid environments is implemented, then productivity is improved, but reliability deteriorates due to sensitivity to environmental conditions and temperature fluctuations

Engineering Contradiction:
Improvedetection speedVSAvoidmeasurement reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by performing hybridization in liquid environment first, then transferring the biosensor to a controlled gaseous environment for measurement. This separates the sample interaction step from the detection step, allowing the measurement to be performed under stable, controlled conditions that minimize environmental interference while maintaining the benefits of liquid-phase hybridization.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces a gaseous environment as an intermediary medium between the liquid sample and the final measurement. By transferring the biosensor from liquid to gas phase for detection, the system eliminates the direct influence of liquid environment fluctuations (temperature, convection, evaporation) on the measurement while preserving the hybridization results achieved in liquid phase.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Enables sensitive and reliable detection of nucleic acid molecules, including single mismatches, without the need for real-time monitoring in liquid environments, providing a reversible and non-destructive method for bioanalysis with improved accuracy and reduced errors.

Implementation Method 1

varying the temperature of the modified bioactive layer so as to produce a change in at least one mechanical feature of said modified bioactive layer

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

the molecules that will bind to it with the highest affinity will be single stranded DNA with the complementary sequence (following the Watson-Crick rules, A with T and G with C)

Methodology Applied
Scientific EffectHydrogen bonding:

Implementation Method 3

The temperature of the modified layer can be controlled by controlling at least one feature (such as the intensity, and/or the duration of light pulses, and/or the time lapse between subsequent light pulses) of light directed onto said mechanical transducer element

Methodology Applied
Scientific EffectBimetallic effect: Bi-Metallic Strip

Data Source

PatentEP2348132B1Method for the bioanalysis of nucleic acid molecules in a sample and biosensor for its implementation
Publication Date: 2013.12.04 CONSEJO SUPERIOR DE INVESTIGACIONES CIENTIFICAS (CSIC)
  • EP2348132B1 patent drawingFigure 1
  • EP2348132B1 patent drawingFigure 2A
  • EP2348132B1 patent drawingFigure 2B

AI summary

The invention is related to the field of nucleic acid biosensors. More specifically, it relates to a method for bioanalysis of a selected type of nucleic acid molecule in a sample based on the behaviour of a gold/silicon layer functionalized with nucleic acids when it is subjected to temperature cycles, the behaviour being different when the target molecule is in the sample or not. The method of the invention is also capable of discriminating the presence of single mismatches in the target molecules. The invention also relates to the system for carrying out the method of the invention.