Reconfigurable Chiral Plasmonic Structures for Naked-Eye Analyte Sensing
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Solution Overview
Problem
Conventional chiral plasmonic sensors suffer from high false-positive/negative rates, require expensive equipment, and are unsuitable for reliable detection outside the laboratory due to environmental variations and weak optical responses.
Innovation Solution
A reconfigurable nanoscaled construct with high anisotropy factors (g-factors up to 16%) and tunable chirality, fabricated using DNA origami techniques, allows for analyte-dependent modulation of chiroptical responses visible to the naked eye, without relying on CD spectrometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional chiral plasmonic sensors use nanomaterial aggregation for detection, then sensitivity is improved, but false positive/negative rates increase due to environmental variations
Solution Approach 1:
The sensor system is segmented into distinct functional modules: chiral plasmonic nanomaterials for signal generation, microfluidic channels for controlled sample delivery, and reference channels for environmental compensation. This segmentation allows independent optimization of each component and reduces cross-interference that causes false readings.
Solution Approach 2:
A reference channel acts as an intermediary element that experiences the same environmental variations as the sample channel but without the analyte. By comparing the differential response between sample and reference channels, environmental interference is cancelled out, eliminating false positives/negatives while maintaining high sensitivity.
2Measurement precision
If CD spectroscopy is used for readout, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The complex CD spectroscopy system is extracted and replaced by a simplified optical readout approach. The chiral plasmonic nanomaterials inherently generate strong optical signals that can be detected with simple colorimetric or fluorescent readouts, eliminating the need for expensive and complex CD spectrometers while maintaining sufficient measurement precision for point-of-care applications.
Solution Approach 2:
The patent employs disposable microfluidic cartridges containing pre-loaded chiral plasmonic nanomaterials. These single-use devices eliminate the need for expensive, complex instrumentation by integrating all necessary components into a low-cost, portable format that can be discarded after one use, making high-precision measurement accessible outside laboratories.
3Measurement precision
If fluorescence-based sensing is used, then detection sensitivity is improved, but auto-fluorescence from biological samples causes false positives
Solution Approach 1:
Instead of trying to eliminate background fluorescence, the system converts this harmful factor into a benefit by using it as an internal reference. The reference channel captures the auto-fluorescence signal, which is then subtracted from the sample channel signal, transforming the interference into a calibration reference that actually improves measurement accuracy.
Solution Approach 2:
The system introduces asymmetry in the optical path by having the sample channel contain both analyte and nanomaterials while the reference channel contains only nanomaterials and buffer. This asymmetric design allows the reference to capture background fluorescence while the sample captures analyte-specific signals, enabling easy mathematical separation of the two components.
4Illumination intensity
If NP aggregation is used for colorimetric sensing, then color change is enhanced, but aggregation can be triggered by impurities instead of analyte
Solution Approach 1:
The chiral plasmonic nanomaterials are pre-assembled into stable, defined structures before sample introduction. This preliminary assembly creates a robust framework that resists non-specific aggregation triggers. The analyte-specific recognition elements are pre-positioned on the nanomaterial surfaces, ensuring that only the target analyte can induce the desired structural changes and colorimetric response.
Solution Approach 2:
The nanomaterials possess localized functional regions with distinct properties: some regions provide structural stability to prevent non-specific aggregation, while other regions contain analyte-specific recognition elements. This local quality differentiation ensures that aggregation is triggered only by the specific analyte binding to recognition sites, not by general environmental conditions or impurities.
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 accurate, fast, and reliable colorimetric detection of analytes in physiologically relevant environments, suitable for point-of-care and remote-area diagnostics with minimal environmental interference.
Implementation Method 1
The use of gold nanorods (AuNRs) show a plasmonic color response that depends on polarization. Since the plasmonic coupling of AuNRs exhibits two orthogonal plasmon resonances
Implementation Method 2
The geometry control in NR dimers allows polarization-dependent plasmon resonances, bringing a quantifiable change in chirality, i.e. circular dichroism (CD) signals
Implementation Method 3
said construct comprising or essentially consisting of a nucleic acid structure with reconfigurable or switchable features
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3(a)~3(c)
AI summary
The present invention is directed to a nanoscaled construct, said construct comprising or essentially consisting of a nucleic acid structure with reconfigurable or switchable features, and at least two separate metallic nanoparticles coupled with said nucleic acid structure, wherein said two separate nanoparticles are at an interchangeable angle to each other, wherein said nanoparticles provide high chirality and/or optical activity within the visible and near-infrared (NIR) spectrum from 400 to 800nm generating a color for the construct, and wherein said construct has an absorption dissymmetry factor (g-factor) of over 10%. There is also provided a method for detecting an analyte in a sample, the method comprising steps of contacting a nanoscaled construct of the present disclosure specific to said analyte with a sample in a test assay, and detecting said analyte in said sample by optical means or by naked eye, wherein the presence of the analyte in said sample changes the color of said nanoscaled structure and the change of color in said assay confirms the presence of the analyte in said sample.