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 | Leave a Comment

Nanoparticle User Survey

If you use nanoparticles in your work or research, we would be pleased to hear your opinions on the concept of a nanoparticle users exchange shop.  This is where lab staff can make their validated reagents available to other users for a price. This service would encourage greater use of niche products not commonly available commercially, less risk as they would be validated and also lead to  more useful research data generated. A nanoparticle exchange facility based on the sharing economy would lead to more data generation and less “reinventing the wheel.”

Complete the short survey at https://goo.gl/forms/6BTDFvasADXYNEXD2

11/10/2017 Posted by | Category 1 | Leave a Comment

Nanomedicine and its delivery problem.

A recent paper by the Chan group in Toronto reviewed the data from published articles on delivery of nanoparticles to tumors over the last decade and found it was not a very efficient process. The median delivery efficiency was as low as 0.7% of an injected dose

http://dx.doi.org/10.1038/natrevmats.2016.14

An excellent article in Chemical and Engineering News discusses the implications of the papers findings with experts in the field highlighting both positive and negative views. The important message is that we need to know how many particles reach their target so that methods to improve nanoparticle design for better delivery can proceed.

http://cen.acs.org/content/cen/articles/94/i25/Does-nanomedicine-delivery-problem.html

What is clear is that for nanomedicine to become a reality, then methods for real time quantification and imaging of nanoparticles  in vivo is required to measure their efficacy. One method applicable to targeting gold nanoparticle is the iodine isotope chemisorption method outlined in our publication    http://rdcu.be/tTwL

24/08/2017 Posted by | Category 1 | Leave a Comment

Real time quantification of gold nanoparticles in experimental use. As simple as plug and play.

The main problem with using gold nanoparticles in life science research is the lack of a simple real time quantification method. Use of mass spectrometry is very accurate but also very expensive and definitely not in real time. It is now possible to quantify gold nanoparticles in real time in experimental procedures by using the chemisorption of Iodine -125 to the gold particles. This simple labelling step involves just mixing the two components. Take your functionalised gold particles and add the isotope. As simple as plug and play. Applications include quantifying in-vitro cell uptake of particles and the potential for imaging in-vivo small animal particle distribution using SPECT (I-125) or PET (I-124) procedures. If nanomedicine is to become a reality, then simple real time methods of imaging and quantification need to be developed. Silver nanoparticles can also be quantified by this method also. Details of our work in understanding the chemistry can be found in a recent publication of the Journal of Nanoparticle Research.         http://rdcu.be/tTwL

03/07/2017 Posted by | Quantification | Leave a Comment

Nanoparticle quantification. When is a mole not a mole ?

The answer is when referring to the “molar” concentration of nanoparticles. There is some ambiguity in discussion groups, blogs and publications regarding the quantification of gold nanoparticles in cell uptake experiments. Some publications refer to gold nanoparticles in terms of molarity. Molarity actually refers to the amount material in a homogeneous solution of molecules  ( or atoms) as a fraction of  its molecular weight in a litre. A property of  1 Mole of material is that it contains 6.023 E23 molecules i.e. Avagadros’ number. Molarity cannot apply to nanoparticles because they are not molecules or homogenous in size. The stated size is a mean based on a spread of slightly different sizes.  If you consider 50 ug/ml of 10nm gold particles there would be about 5 E12 particles and a molarity of 0.25 mM with respect to elemental gold. A 50 ug/ml of 20 nm gold particles would be of the same molarity (0.25mM) but would contain about 0.6 E12 particles. So quoting molarity of gold has to refer to the amount of gold atoms present but without the mean particle size as well the molarity would be meaningless.  To confuse the issue even more  there are some publications where they refer to the Molar extinction coefficients of nanoparticles which appear to be based on Avagadros number rather than molecular weight as nanoparticles don’t have a molecular weight .  This is quite a useful was to express the number of particles used but the nomenclature leads to ambiguity.  A specific term such as the “particulate molarity” would distinguish  quantification based on numbers of particles rather than gold atoms. To summarise whatever method is used to state the quantity of gold particles used it should be clear that molarity  refers to elemental gold  and that quantity based on Avagadros’ number should be expressed in a more specific term than just molarity. Personally I just prefer to use g/l or particles/ml but also including the mean particle size.

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18/11/2015 Posted by | Quantification | | Leave a Comment

Welcome to the Nano Biosols gold-blog: a potted history of the technology

 

Welcome to the Nano Biosols gold-blog.  Nano Biosols is a new start up supplying gold nanoparticles to industry and  the bio-medical research community with a view to developing the technology in the future.  In the 1970’s  we were introduced to the concept of immunogold. The only application was in immonoelectron microscopy where particles were visualised as  black dots where they bound on biological samples. Through innovative steps the particles were also used in light microscopy and protein blotting techniques  in combination with silver enhancement techniques. The second generation of gold based reagents were developed to be used  in lateral flow in-vitro diagnostic assays due to their macroscopic ruby red colour. It was around the new millennium in 2000 that the term nanoparticle appeared in relation to gold and the concept of the third major application surfaced in the form of therapeutics. The concept of nanomedicine , i.e. use of nanomaterials as therapeutic agents in medicine had developed. It is expected that these theranostics will have multi-modal properties of targeting, imaging and delivering a therapeutic effect. The future looks bright for the continuous development of applications of gold nanoparticles  even in other non biological sectors such as catalysis and solar energy. Who knows where the next  innovative application of these versatile materials will take us ? I hope this blog can be a sounding board for new ideas, applications and problem solving in the nano gold community.

logo_1104853_print    www.nanobiosols.com

11/11/2015 Posted by | News | | 1 Comment