Common Applications of Gold Nanoparticles

I. Biomedical Field  

(1) Immunolabeling Technology  

Principle: Utilizing the property that gold nanoparticles can bind to biological molecules such as antibodies or proteins without affecting their biological activity, the detection of target substances is achieved through antigen-antibody specific reactions. In immunoblotting, gold nanoparticle-labeled antibodies bind to target antigens, and detection is performed by their color change or enhanced visualization using a silver developer.  

(2) Rapid Diagnostic Test Strip

Principle: Based on colloidal gold immunochromatography, the test strip is pre-coated with gold nanoparticle-labeled COVID-19-specific antibodies, as well as corresponding antibodies on the test line and control line. When a sample is dropped onto the strip, if COVID-19 antigens are present, they first bind to the gold nanoparticle-labeled antibodies to form complexes. These complexes migrate along the strip via capillary action. When reaching the test line, they bind to another immobilized COVID-19 antibody, causing gold nanoparticles to aggregate and develop color. The control line validates the strip's effectiveness.  

(3) Targeted Drug Carrier  

Principle: Gold nanoparticles have good biocompatibility and a large specific surface area, allowing modification with specific ligands (e.g., antibodies, peptides) on their surface. These ligands bind to specific receptors on diseased tissues or cells, enabling precise delivery of drugs loaded on gold nanoparticles to target sites. For example, anticancer drugs are conjugated to gold nanoparticles via chemical coupling, and antibodies specific to tumor cell surface receptors (e.g., anti-HER2 antibodies for HER2-positive breast cancer) are modified to enhance targeting.  

(4) Photothermal Therapy  

Principle: Gold nanoparticles exhibit unique surface plasmon resonance. When irradiated by near-infrared light, their surface free electrons oscillate collectively, absorbing light energy and converting it into heat, rapidly increasing local temperature. By accumulating gold nanoparticles in tumor tissues and irradiating with near-infrared light, tumor cells are thermally ablated with minimal damage to surrounding normal tissues.  

(5) Antibacterial Materials  

Principle: Gold nanoparticles possess antibacterial activity, possibly by disrupting bacterial cell membranes or interfering with bacterial metabolism. Loading gold nanoparticles onto material surfaces (e.g., medical antibacterial materials, cell/tissue culture scaffolds) effectively inhibits bacterial growth and reproduction.  

II. Catalysis Field  

Principle: Gold nanoparticles supported on oxide carriers act as catalysts, reducing the activation energy of CO oxidation reactions, and enabling efficient conversion of CO to CO? at low temperatures. Interactions between gold nanoparticles and oxide carriers modify the electronic structure and surface properties of gold nanoparticles, enhancing their catalytic activity.  

III. Optical Materials Field  

(1) Surface-Enhanced Raman Scattering (SERS) Substrate  

Principle: The surface plasmon resonance of gold nanoparticles enhances Raman scattering signals of surrounding molecules. When molecules adsorb on gold nanoparticles or lie within their near-field, interactions between gold nanoparticles and molecules, combined with localized electromagnetic field enhancement from surface plasmon resonance, significantly amplify Raman signals, enabling highly sensitive detection of trace substances.  

(2) Preparation of Nanocomposites with Special Optical Properties (taking gold nanoparticle-polymer nanocomposites as an example)  

Principle: Incorporating gold nanoparticles into polymer matrices leads to interactions between their optical properties and polymer characteristics, endowing composites with unique optical performance. For instance, the surface plasmon resonance absorption peak of gold nanoparticles grants composites unique absorption in specific wavelength ranges, while interfacial interactions between gold nanoparticles and polymers affect properties like optical transparency.  

IV. Environmental Monitoring Field  

Principle: Gold nanoparticles exhibit a specific color in solution. In the presence of mercury ions, specific reactions with surface groups of gold nanoparticles cause aggregation or surface property changes, altering solution color. Qualitative and quantitative detection of mercury ions in water is achieved by visual observation or spectral analysis of color changes.