Gold Colloid is a colloidal gold particle produced from chloroauric acid under the influence of a reducing agent. Due to its negatively charged surface, it can interact with positively charged molecules such as proteins, allowing them to bind firmly to the surface of the colloidal gold. Therefore, gold colloid, as a tracer, is widely used in immunodiagnostic products. Gold colloids prepared by traditional methods exhibit poor uniformity and low concentration (0.01%-0.04%). Aladdin's gold colloids demonstrate excellent uniformity, exhibiting monodispersity (particle size CV < 8%) and high concentration (1%), and they also feature high labeling efficiency, saving labeling materials and energy consumption, and simple operation.
Product advantages
1、Saving active materials: High-concentration colloidal gold has high labeling efficiency, saving more than 50% of active materials;
2、Shortening supply cycle: High-concentration operation reduces centrifugation time, reduces the investment in large centrifuge equipment, and shortens the supply cycle;
3、Excellent monodispersity: PDI is below 0.2, reducing batch-to-batch variability.
Product Concentration
100±5 OD (at the maximum UV absorption wavelength)
Instructions for Use
I. Determination of Optimal Labeling Conditions
1、Dilute ultra-high concentration colloidal gold to 40 OD using buffers of different pH values (e.g., 40 μL ultra-high concentration colloidal gold + 60 μL buffer).
2、Add labeling protein (antigen or antibody) at the same concentration to each sample; the recommended labeling concentration is 50 μg/mL–120 μg/mL. React with shaking at room temperature for 15 min to 2 h.
3、After the reaction, collect a small volume of the labeled concentrated gold solution and dilute it to 1 OD with purified water (e.g., 25 μL labeled ultra-high concentration colloidal gold + 975 μL purified water).
4、Add 100 μL of 10% NaCl to each milliliter of the 1 OD labeled colloidal gold solution. Mix by shaking and observe the color change. The condition showing the least color change or minimal aggregation after 5 minutes is the optimal labeling pH for the labeling protein.
5、If all tested pH buffer conditions result in color change or aggregation, add 0.04% NaCl to the labeling buffer or increase the labeling concentration, then repeat the above optimal pH determination procedure.
*Note: 10 mM phosphate buffer, borate-borax buffer, or carbonate buffer is recommended.
II. Labeling of Ultra-High Concentration Colloidal Gold
Perform labeling using the optimal conditions determined in the screening step.
III. Blocking
Add an appropriate amount of colloidal gold blocking agent and react with shaking for 20 minutes.
IV. Purification and Resuspension
Centrifuge → Discard the supernatant → Resuspend the pellet with colloidal gold resuspension buffer to the target concentration.
Precautions
a). Storage: This product can be transported at room temperature. After receipt, storage at 4 °C–8 °C is recommended. Avoid placing it at air vents or inner walls of the refrigerator compartment. Freezing is strictly prohibited. Stratification after long-term storage and gold spots on the inner bottle wall caused by water evaporation are normal phenomena and generally do not affect usage.
b). When aliquoting or dispensing, use clean containers to prevent colloidal gold aggregation due to contamination. PC transparent material is recommended.
c). Use the product within 2 months after opening.
d). For buffers used in colloidal gold labeling, BND or NaN₃ preservatives are recommended; the ProClin series should be avoided.
e). The pH of the colloidal gold solution may change after long-term storage. Re-optimization of labeling conditions prior to use is recommended.
Disclaimer
a). Any adhesion, aggregation, dead gold, or abnormal state of colloidal gold caused by improper storage or use shall be the sole responsibility of the user.
b). The product must be inspected and verified as qualified before use. Any consequences arising from direct use without prior product inspection shall be the sole responsibility of the user.
Comprehensive hazard, handling, storage, and regulatory compliance document.
Download SDS →Lot-specific quality data. Enter your lot number to retrieve the exact COA.
Look up COA →Full quality attributes and acceptance criteria for this grade.
View spec sheet →