Carbohydrate-Capped Metal Nanoparticles for DNA Detection
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Solution Overview
Problem
Current methods for detecting foodborne pathogens, such as Salmonella spp. and Shiga toxin-producing Escherichia coli, are hindered by the need for costly reagents, advanced equipment, and trained personnel, and existing colorimetric gold nanoparticle biosensors require pre-treatment steps and lengthy functionalization processes, limiting accessibility and rapid detection capabilities.
Innovation Solution
A method involving aminated oligonucleotide probes and carboxylic-functionalized carbohydrate-capped metal nanoparticles, where the nanoparticles form a stable complex with target DNA, while non-target adducts aggregate upon acid addition, allowing for rapid and accessible detection without expensive equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional enumerative techniques are used for detecting foodborne pathogens, then detection reliability is improved, but detection time increases to days and equipment complexity increases
Solution Approach 1:
The patent replaces traditional mechanical/culturing-based detection methods with a colorimetric nanoparticle-based detection system. The method uses gold nanoparticles functionalized with probes that bind to target DNA, producing a visible color change that indicates pathogen presence, eliminating the need for days of culturing and complex laboratory equipment.
Solution Approach 2:
The patent employs colorimetric detection where gold nanoparticles undergo visible color changes based on their aggregation state. The nanoparticles transition from a red color (dispersed state) to a blue/purple color (aggregated state), providing a simple visual readout that enables rapid detection without requiring sophisticated analytical equipment.
2Loss of time
If PCR techniques are used for rapid detection, then detection time is reduced to hours, but device complexity and cost increase due to advanced equipment and trained personnel requirements
Solution Approach 1:
The patent uses disposable, pre-functionalized gold nanoparticle probes that can be easily prepared and discarded after use. These nanoparticles are functionalized with specific probes that bind to target DNA sequences, providing a simple, low-cost alternative to expensive PCR reagents and equipment while maintaining rapid detection capabilities.
Solution Approach 2:
The patent substitutes complex molecular biology techniques (PCR) with a simpler colorimetric nanoparticle binding assay. Instead of requiring thermal cyclers, fluorescent detectors, and trained personnel, the method uses visual color changes of gold nanoparticles to indicate detection, making it accessible in resource-limited settings.
3Reliability
If immunological assays such as ELISA are used, then detection capability is improved, but personnel requirements and storage needs increase
Solution Approach 1:
The patent employs disposable gold nanoparticle probes that are pre-functionalized with detection capabilities. These nanoparticles can be stored stably and discarded after use, eliminating the need for expensive, cold-chain stored antibodies and complex immunoassay equipment required by ELISA methods.
Solution Approach 2:
The patent changes the detection parameter from antibody-antigen binding (requiring cold storage and specialized equipment) to nanoparticle aggregation-induced color changes. This parameter change enables detection at room temperature without requiring specialized storage facilities or trained personnel for assay execution.
4Ease of operation
If colorimetric gold nanoparticle biosensors are used for pathogen detection, then detection accessibility is improved, but functionalization time increases to days
Solution Approach 1:
The patent uses pre-functionalized gold nanoparticle probes that are prepared in advance with specific binding molecules attached. This preliminary action eliminates the need for time-consuming in-assay functionalization steps, allowing users to simply mix the pre-prepared probes with their samples and read results based on color changes, thereby maintaining accessibility while reducing operational time.
5Ease of manufacture
If salt is added to disrupt electrostatic repulsion in GNP solutions, then particle aggregation is induced for detection, but non-target adducts aggregate causing false positives
Solution Approach 1:
The patent applies local quality by creating different surface properties on gold nanoparticles based on whether they are bound to target DNA or not. Nanoparticles bound to target DNA have different surface characteristics compared to free nanoparticles, causing them to respond differently to salt addition. This local differentiation ensures that only non-target adducts aggregate and change color, while target-bound nanoparticles remain stable, eliminating false positives.
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 rapid, cost-effective detection of target DNA analytes with minimal equipment requirements, providing a stable and measurable color change that correlates with the presence of pathogens, thereby improving accessibility and reducing detection time.
Implementation Method 1
They also feature unique optical properties. The coherent oscillation of free electrons in colloidal GNP solutions produces a strong SPR (Surface Plasmon Resonance) band. As this SPR band is distance dependent, aggregation of the nanoparticles leads to a visible color change.
Implementation Method 2
aggregation of the nanoparticles leads to a visible color change. Small and dispersed gold nanoparticles will feature a peak absorbance around 520 nm and appear red in color, while the aggregation of particles will lead to higher peak wavelength absorbance (approximately 600 or higher) and a visible color change to blue or purple.
Data Source
AI summary
The disclosure relates to methods, apparatus, and compositions for analyzing a sample for the presence or absence of a target DNA analyte. A sample mixture is formed, which includes a sample to be analyzed and a nanoparticle-probe adduct. The nanoparticle-probe adduct is a non-covalently-bound adduct between a functionalized carbohydrate-capped metal nanoparticle and a functionalized oligonucleotide probe specific to the target DNA analyte. Upon thermal treatment of the sample mixture, a nanoparticle-probe-DNA complex forms when the target DNA analyte is present in the sample. Upon addition of a destabilizing agent (such as an acid) to the thermally treated sample mixture, remaining non-complexed nanoparticle-probe adduct will aggregate or otherwise becomes destabilized, creating a rapidly detectable color change that can be detected and correlated to the presence or absence of the target DNA in the original sample. Related apparatus, kits, and compositions for performing the methods are also disclosed.