Nano Biosols goldblog

nanoparticles for biological solutions

Silver enhancement increases sensitivity by at least a hundredfold

Gold nanoparticles are used routinely in hundreds of assays known as lateral flow or “flow through” assays. The main properties are that they are cheap and give a clear red visual image when an assay gives a positive result. They are incorporated into simple disposable tests that do not require sophisticated equipment.

The main disadvantage is that they may not be as sensitive as other methods. If the analyte in question is a nucleic acid, then this type of analyte can be amplified by PCR or LAMP amplification techniques. If the analyte is a protein or molecule detected by an antibody then the only way to increase the sensitivity is by modifying the detection method to be more sensitive.

With gold nanoprobes this increase in sensitivity can be achieved by silver enhancement, which can increase the sensitivity a hundredfold. In addition the silver enhancement produces a black stain giving a greater contrast in colour making it much easier to confirm a positive result.

If you are developing gold based assays and want at least a hundred fold increase in sensitivity then try our Silver Stain kit.

 Example.

Gold particles (10 nm) were dotted in 1µl volumes at tenfold dilutions from 20 femtomoles  (12 x 10particles/dot) to 20 attomoles (12 x 106 particles/dot) on nitrocellulose. After blocking and rinsing in water the dots were incubated with our Silver Stain kit for 10 minutes.

Result. The top row is silver enhanced gold dots decreasing in concentration from the left. The lower row is just the gold dots at the same concentration The second dot of unstained gold is barely visible at this concentration but when silver stained it is clearly visible and the sensitivity increase is clearly at least a hundredfold and of greater contrast

20 fM   2 fM       0.2 fM     20 aM     Control

An excellent review of quantitative biosensing applications of silver enhanced gold nanoparticles can be found at

http://dx.doi.org/10.1080/05704928.2013.807817

12/04/2018 - Posted by | Category 1

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