Au/Ag Core-Shell Nanoparticle Biosensor Stability
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Solution Overview
Problem
Current biosensors face challenges in maintaining stability and sensitivity for bio-material detection at high salt concentrations and temperatures, as well as in effectively utilizing the optical characteristics of both Au and Ag nanoparticles, often resulting in nonspecific staining and false positives due to the limitations of Au-Ag core-shell composites and alloy nanoparticles.
Innovation Solution
An Au/Ag core-shell composite is developed where an Au nanoparticle is surrounded by an Ag nanoparticle layer, with a receptor bonded to the Au surface and its recognition site exposed outside the Ag layer, enabling stable bonding and enhanced optical properties for sensitive bio-material detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Au nanoparticle is used for biosensor, then stability at high salt concentration and temperature is improved, but SERS effect is weakened
Solution Approach 1:
The patent creates an Au/Ag core-shell composite nanoparticle where the core is made of Au nanoparticle and the shell is made of Ag nanoparticle. This composite structure combines the stability advantage of Au nanoparticle (resistance to aggregation at high salt concentration and temperature) with the superior SERS effect of Ag nanoparticle, thereby resolving the contradiction between stability and measurement precision.
2Measurement precision
If Ag nanoparticle is used for SERS, then SERS effect is improved, but stability at high salt concentration and temperature is worsened
Solution Approach 1:
The Au/Ag core-shell composite structure places Ag nanoparticle as the shell to provide strong SERS effect while the Au nanoparticle core provides structural stability. The shell thickness is controlled to maintain both optical characteristics and stability, resolving the contradiction between measurement precision and reliability.
3Reliability
If Ag/Au core-shell composite is used with Ag core and Au shell, then stability is improved, but optical characteristics of Ag nanoparticle cannot be utilized
Solution Approach 1:
The patent inverts the conventional Ag/Au core-shell structure to create an Au/Ag core-shell structure. By placing Au at the core and Ag at the shell, the invention maintains stability (from Au core) while enabling utilization of Ag's superior optical characteristics and SERS effect from the shell, thereby resolving the contradiction between stability and optical characteristics.
4Reliability
If Au-Ag alloy nanoparticle is used, then both stability and optical characteristics are improved, but irreversible aggregation occurs at high salt concentration
Solution Approach 1:
Instead of using Au-Ag alloy nanoparticle which undergoes irreversible aggregation, the patent employs a core-shell composite structure where Au core and Ag shell are distinct phases. This composite structure maintains the resistance to aggregation of pure Au nanoparticle while incorporating the optical advantages of Ag, resolving the contradiction between stability and compositional stability.
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 Au/Ag core-shell composite provides stable performance under high salt concentrations and temperatures, allowing for ultra-high sensitivity and efficient detection of bio-materials, reducing nonspecific staining and improving detection accuracy.
Implementation Method 1
Gold (Au) nanoparticle exhibits physical, chemical and optical properties due to specific Surface Plasmon Resonance (SPR)
Implementation Method 2
since Raman scattering effect of Au nanoparticle is weaker than that of Silver (Ag) nanoparticle, Au nanoparticle is low in surface enhanced Raman Scattering (SERS) effect
Implementation Method 3
oligonucleotide can form a strong hydrogen bond with a target DNA having a complementary sequence
Implementation Method 4
protein can form a strong bond with a target protein through an antigen-antibody reaction
Data Source
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AI summary
In accordance with an aspect of the present invention, there is provided an Au/Ag core-shell composite including an Au nanoparticle; an Ag nanoparticle layer surrounding the Au nanoparticle; and a receptor having a target material recognition site bondable or reactable with a target material, wherein one end of the receptor is bonded on the surface of the Au nanoparticle, so that a portion of the receptor is embedded into the Ag nanoparticle layer, and the target material recognition site is exposed to the outside of the Ag nanoparticle layer. The Au/Ag core-shell composite can provide a stable bond between Au nanoparticle and organic molecule, and superior optical characteristics of Ag nanoparticle. Thus, a biosensor using the composite in accordance with anaspect of the present invention can effectively and efficiently detect target bio material and be variously used in medical and pharmaceutics.