Nano-plasmonic Molecular Probes for SERS Detection
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Solution Overview
Problem
Current methods for detecting nucleic acid targets, such as DNA or RNA, using surface-enhanced Raman scattering (SERS) face challenges in achieving sensitive and selective detection due to the distance-dependent decay of electromagnetic field enhancements near metal nanoparticles, limiting the effectiveness of SERS signals.
Innovation Solution
The development of nano-plasmonic molecular probes comprising metal nanoparticles, oligonucleotides, and optical labels that change their conformation upon target hybridization, allowing the label to move into the vicinity of the nanoparticle for enhanced SERS signal detection, and the use of silver-coated gold nanostars to produce probes that can self-assemble for improved field enhancement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional SERS detection methods are used with metal nanoparticles, then detection capability is provided, but the electromagnetic field enhancement decays rapidly with distance, limiting detection sensitivity
Solution Approach 1:
The invention employs dynamic conformational changes in DNA hairpin structures that bring the optical label close to the nanoparticle surface only upon target hybridization. The hairpin opens from a closed state (label far from surface) to an open state (label near surface), making the distance dynamic rather than static, thus overcoming the rapid field decay limitation
Solution Approach 2:
The DNA hairpin structure acts as an intermediary mechanism that controls the position of the optical label relative to the nanoparticle. It mediates between the target recognition event and the SERS signal generation, translating molecular binding into spatial positioning that maximizes electromagnetic field enhancement
2Measurement precision
If the optical label is kept close to the nanoparticle for enhanced SERS signal, then detection sensitivity improves, but the probe cannot distinguish between bound and unbound states
Solution Approach 1:
The system uses dynamic conformational switching of the DNA hairpin that is triggered specifically by target hybridization. In the absence of target, the hairpin remains closed keeping the label far from the nanoparticle (low signal). Upon target binding, the hairpin opens bringing the label close (high signal), creating a reliable on/off signal distinction
Solution Approach 2:
The invention changes the spatial parameter (distance between label and nanoparticle) as a function of target presence. The system transitions between two distinct states: far distance (no target) and close distance (target present), using this parameter change to achieve both signal enhancement and selective detection
3Measurement precision
If single metal nanoparticles are used for SERS detection, then the structure is simple, but the electromagnetic field enhancement is insufficient for highly sensitive detection
Solution Approach 1:
The invention uses composite nanoparticle structures combining gold and silver materials (e.g., gold nanostars coated with silver, or gold-silver alloy nanoparticles). These composite structures leverage the plasmonic properties of both metals to achieve superior electromagnetic field enhancement compared to single-material nanoparticles, while maintaining relatively simple spherical or star-shaped geometries
4Ease of manufacture
If the nanoprobe structure is simplified for ease of manufacture, then production becomes easier, but the ability to control label positioning and conformational changes is reduced
Solution Approach 1:
The oligonucleotide is segmented into distinct functional domains: a stem region that forms the hairpin structure, a loop region that contains the target-binding sequence, and a placeholder region that controls conformational switching. This segmentation allows each region to perform its specific function while maintaining overall structural simplicity for manufacturing
Solution Approach 2:
The placeholder sequence acts as an intermediary element within the oligonucleotide structure that mediates between the stem and loop regions. It controls the conformational transition by providing a binding site that stabilizes the closed hairpin state until target displacement occurs, enabling reliable switching without complex structural design
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
This approach enables sensitive and selective detection of nucleic acid targets with enhanced SERS signals, allowing for multiplexed detection and potential therapeutic applications by exploiting the tunability of spectral properties of metal nanoparticles.
Implementation Method 1
Plasmon resonances on the substrate surfaces, also called surface plasmons, provide a major contribution to electromagnetic enhancement. Incident light irradiating these surfaces excites conduction electrons in the metal, and induces excitation of surface plasmons leading to Raman/Luminescence enhancement.
Implementation Method 2
The first class of enhancements is further divided into several processes. Plasma resonances on the substrate surfaces, also called surface plasmons, provide a major contribution to electromagnetic enhancement.
Implementation Method 3
Surface enhanced Raman scattering (SERS) effect. The use of SERS measurement for a variety of chemicals including several homocyclic and heterocyclic polyaromatic compounds has been reported.
Data Source
AI summary
Plasmonics-active nanoprobes are provided for detection of target biomolecules including nucleic acids, proteins, and small molecules. The nucleic acids that can be detected include RNA, DNA, mRNA, microRNA, and small nucleotide polymorphisms (SNPs). The nanoproprobes can be used in vito in sensitive detection methods for diagnosis of diseases and disorders including cancer. Multiplexing can be performed using the nanoprobes such that multiple targets can be detected simultaneously in a single sample. The methods of use of the nanoprobes include detection by a visible color change. The nanoprobes can be used in vivo for treatment of undesirable cells in a subject.