A11 Gold Nanoparticles Additional Information

 

 

 

	MW (g/mole)	Zeta Charge (mV)	Salt resistant?	Concentration Sensitive?	Easy to adsorb proteins?	Easy to thiolate?	Shelf Life at 4C
Citrate	192	-35	1.5mM	Yes	Yes	Yes	6 months
Nanopartz Carboxylic Acid	212	-30	15mM	Less than Citrate	Better than Citrate	Better than Citrate	years
PEI	100K	30	150mM	No	Yes	Yes	6 months
PAA	10K	-30	150mM	No	Yes	Yes	6 months
PAH	10K	20	150mM	No	Yes	Yes	6 months
PVP	40K	-10	0.5M	No	No	Yes	6 months
CTAB	364	35	0.5M	Yes	No	No	6 months
BSA	66K	-15	0.5M	No	No	No	6 months

 

Composition

These spherical gold nanoparticles are shipped in  DI water with no measurable residual reactants. These particles are not manufactured in citrate. Citrate and the other ligands are functionalized after manufacturing allowing for a minimal, controlled amount of ligand to be used.

Custom Formulation

Diameters 1.8nm to 1500nm.  Other sizes are special order.  Please contact us.

Quantity

This product is available in 1mL volumes and larger. For orders larger than 1L, or for orders amounting over 10L per annum, please contact sales for quantity pricing.

Introductory Kits

25mL volume with a four bottle minimum, online ordering only, citrate only.

Delivery

Standard sizes are in stock. Special order sizes are shipped in two weeks or less. All domestic shipments are sent Fed Ex Standard Overnight delivery, international Fed Ex Priority 2 day. No shipments on Fridays except for dried particles. Saturday shipping available for extra charge.

Functionalization

This product comes with different adsorbed ligands: our proprietary carboxylic acid, citrate, and with PEI, PAH, PAA, BSA, and PVP polymers.

Shelf Life/Storage Temperature

This product is guaranteed for six months and should be stored at 4 °C after opening. Care must be taken to only use sterile glassware when working with this product.

Toxicity

This product is known to be noncytotoxic. This product has been sterilized and is biological free.

Sterilization

This product is sterilized.

The manufacturing method for these nanoparticles are based on our proprietary method. This invention allowed the first use of a reducing agent to be used at room temperature. Unlike citrate which is only a reducing agent at the boiling temperature of water - thereby quickly making non-monodisperse gold nanoparticles, our reducing agent works by slowing building nanoparticles from seed, atom by atom, over the course of up to hours. The result is a highly monodisperse product with unrivaled spherical shapes.

All of these "bare" particles are capped with ligands that are easily replaced with thiol and charge chemistries. We do not recommend using the carboxyl termination on our proprietary ligand as a conjugatable attachment.

Certifications

Every order comes with a Certification of Analysis that includes the following information. We use calibration traceable:

UV-VIS (Agilent 8453) for extinction and concentration measurements

NIR (Cary 500) for NIR extinction and concentration measurements

DLS (Malvern Nano ZS) for zeta potential measurement

ICP-MS (Varian 820-MS) for gold mass measurements

TEM (Phillips CM-100 100KV) for sizing

TN602 Storage and Handling

TN801 UV VIS to Determine Size and Concentration

SDS Part # A11

Sole Source Advantages

Why are your spherical gold nanoparticles so much more monodisperse than conventional citrate stabilized gold nanoparticles?

Citrate stabilized gold nanoparticles are manufactured by combining sodium citrate and hydrogen tetrachloroaurate (gold) in water. In this combination, citrate not only acts as the capping agent, it also reduces the gold to a charge state that allows nanoparticles to form. However, citrate is only a reducing agent at the boiling point of water - so the solution must be boiled. Nanoparticle monodispersity is dependent on an even, homogeneous concentration of the chemical components in solution, and because boiling introduces heterogeneity into the process, the result is a very heterogeneous product.

Our manufacturing method is based on the slow reduction of hydrogen tetrachloroaurate in water. By slowly adding gold over time, we can control the growth, shape, and monodispersity of the gold nanoparticles to within 2nm accuracies.

Why are your citrate stabilized gold nanoparticles so much more monodisperse than conventional gold nanoparticles?

We use our capping agent to manufacture the highly monodisperse gold nanoparticles and then ligand exchange our capping agent with citrate. Since the binding energy (k) for citrate is so much stronger than our capping agent, our capping agent is readily replaced.

How do you size your gold nanoparticles? Does the size include the capping agent?

We use three methods to specify our gold nanoparticles; TEM, UV VIS, and DLS. Each has its own advantages and disadvantages, and we use a weighted system to take advantage of each methods strengths. In the end, we place the strongest weight to the TEM method, particularly since we use samples sizes greater than 50 particles for each lot.

Do you really provide a TEM for my specific lot?

Yes, and not just for 5-10 particles, rather 50-100 are standard.

Why are your small gold nanoparticles colored? I have seen 2nm particles on other website that look as clear as water.

All gold nanoparticles absorb and/or scatter. If you can't see them, then they probably aren't there.

What is OD?

Optical Density (OD) is measured by UV-VIS. An Optical Density OD=1 corresponds to a transmission of 10% through a 1cm cuvette. Optical Density is a nice unit to use since Optical Densities correlate linearly to concentration. So an Optical Density of 1.2 is equal to 1.2 times the concentration of a gold nanoparticle solution that has an Optical Density of 1. We use OD and concentration interchangingly as it is easier to refer to a solution of OD=1 rather than 2.35e12 nanoparticles. For all spheres up to 200nm, OD=1 does refer to 0.05mg/mL.

What is PDI?

PDI refers to polydispersity index and is equal to the standard deviation of the particle sizes divided by the average size.

Why is your shelf life time so much longer for your proprietary gold nanoparticles when compared to citrate stabilized gold nanoparticles?

As opposed to citrate, our Nanopartz Carboxylic Acid capping agent is not a growth medium.

Are your proprietary gold nanoparticles interchangeable with citrate stabilized gold nanoparticles?

Yes. However, the user must be aware that in order to stabilize citrate gold nanoparticles, previous manufacturers used to add many stabilizing agents. Consequently for example to ionically attach ligands to gold nanoparticles required the chemist to "drive" the reaction by adding 10-1000 times greater concentrations of the ligand. This is no longer necessary with our gold nanoparticles.

 

"In our multiphoton photoemission experiments, which are extra sensitive to any variations in nanoparticle geometry, we find Nanopartz rods and spheres to be consistently high quality. The photoemission distributions and other properties are representative of the fundamental particle shape, rather than defects, aggregates, or particle heterogeneity. The Nanopartz team is friendly, helpful, and knowledgeable - our go-to for publication-quality commercial nanoparticles."

Jacob Pettine, NSF Graduate Research Fellow

JILA, University of Colorado Boulder

 

"We were previously making our own gold nanoparticles using the commonly used technique of citrate reduction of Au(III). The colloids generated are broadly polydisperse, and we were concerned that our application of these particles in immuno-gold labeling of cells for optical coherence microscopy (OCM) would be utilizing only the large diameter tail of the distribution. We purchased the sampler package of NanoPartz gold spheres (30 nm, 50 nm, 70 nm, 90 nm) and examined each size carefully with dynamic light scattering, OCM, and spectrophotometry. Our measurements indicated diameters a couple nanometers larger than specifications (a result of measurements on the fully hydrated state?), and remarkable monodispersity - within specs. It is clear to us now that our early immuno-gold results were dominated by the largest diameter spheres of our early colloids. We are delighted by the NanoPartz monodisperse preparations and recommend them strongly!"

Dr. Richard C. Haskell 
Professor of Physics & Director of Physics Clinic 
Physics Department 
Harvey Mudd College

"The scientists at Nanopartz have developed a line of colloidal gold nanorods with extremely high monodispersity in size, shape, and mass. The surfactant layer is highly stable and readily displaced for biofunctionalization. In every test, in vitro and in vivo, these materials have exceeded our expectations."

Geoffrey A. von Maltzahn
NSF and Whitaker Graduate Fellow
Harvard-MIT Division of Health Sciences and Technology
Laboratory for Multiscale Regenerative Technologies

 

 

The manufacturing method for these nanoparticles are based on our proprietary method. This invention allowed the first use of a reducing agent to be used at room temperature. Unlike citrate which is only a reducing agent at the boiling temperature of water - thereby quickly making non-monodisperse gold nanoparticles, our reducing agent works by slowing building nanoparticles from seed, atom by atom, over the course of up to hours. The result is a highly monodisperse product with unrivaled spherical shapes.

All of these "bare" particles are capped with ligands that are easily replaced with thiol and charge chemistries. We do not recommend using the carboxyl termination on our proprietary ligand as a conjugatable attachment.

	Nanopartz™Accurate™ Spherical Gold Nanoparticles	Other Technologies
Monodispersity	High (<2%)	Low (>15%)
Size Accuracy	High (+/-2nm)	Low
Linewidths	Narrow	Broad
Storage lifetime	Years	6 months at 4C
Ability to ligand exchange	Easy	More difficult

 

• Highly accurate and monodisperse in size, shape, and batch to batch uniformity.
  • Monodisperse sizes and shapes leads to better standards for electron microscopy and other diagnostics.
• Accurate to +/- 2 nm in diameter.
  • More accurate sizing makes for better SPR matching for Surface Enhanced Raman Labels.
• Size monodispersity better than 4% CV for many sizes.
  • Monodisperse sizes and shapes leads to better Resonance Light Scattering labels in sensitivity and multiplexing
• Greater than 99.9% spheres.
• Carboxylic acid capping agent is reduced to < 0.1% without adverse effects to the spheres.
  • Reduced number of additives improves binding to antibodies, receptors, ligands and DNA.
• Extremely stable.  Shelf life is greater than one year.  May be stored at room temperature for extended periods.
• The light scattering power of a 60 nm gold particle is equivalent to ~5 X 10⁵ fluorescein molecules.
• Accurate™ SGNPs do not photobleach.
  • No photobleaching means better diagnostic labels with the ability to archive.
• Light scatter can be detected by the unaided eye at particle concentrations as low as 10^-15 M (femtomolar) in suspension and as low as 0.005 particles/m² on a transparent surface.
  • 10⁵ better scattering power than fluorescein means lower limits of detection with simpler instrumentation.
• Individual gold nanoparticles can be seen by eye in an inexpensive student microscope with simple dark field illumination allowing for very sensitive and inexpensive particle counting assays.
• Different sized particles scatter different colors of light and therefore can be used as multicolor multiplexed labels.
• Facile conjugations allow for coating of antibodies, receptors, ligands, DNA without affecting their light scattering properties.
• Slightly negatively charged (reduced aggregation).
• Facile synthesis.  Gold chemistry is well known.
• No known cytotoxicity