Applications of Gold Conjugates
Gold nanoparticles are incorporated into numerous technologies and applications.
Some of the most common gold nanoparticle applications are ideal for:
- Diagnostics: Gold nanoparticles are readily conjugated to antibodies,
peptides, synthetic oligonucleotides, and other proteins due to the affinity of
functional groups on the gold surface. Nanogold conjugates have been widely incorporated
into diagnostic applications, where their bright red color is used in home and point-of-care
test such as the home pregnancy tests.
- Therapeutics: Gold colloid nanoparticles are being investigated
as agents for photothermal- and microwave-based therapeutics. Typically, this involves
functionalizing the nanoparticle surface with an antibody or antibody fragment that
specifically targets tumor cells. After reaching the tumor, the nanoparticles are
illuminated with infrared or microwave radiation, both of which pass through skin
and tissue, causing the nanoparticles to heat up, destroying the tumor cells.
- Electron Microscopy: Conjugation of antibody with gold nanoparticle
has specific targeting, when used to stain tissues and cells for subsequent imaging
using a tansmission electron microscope. These electron-dense and visually opaque
nature of gold labels provide an excellent contrast agent for TEM imaging, as has
a much larger electron density than biomolecules. Various size of gold particles
can be used to labeled with different atnibody for multiparameter experiments.
The use of Bio-Synthesis's unique expertise in bioconjugation chemistries, we ensures
high quality conjugates are produced.
- No gold particle clusters
- Stable and reproducible
- No non-specific binding
- Optimized to meet you sensitivity specifications
- Small scale to bulk manufacturing
Contact our Technical Service Center at 800.220.0627 or contact
us online with your detail project specifications, a project manager will
be assigned to help you with design and develop an appropreate synthetic method
for your specific needs.
Sample Submission Requirement:
Biomolecule supplied by customers should be sufficiently pure. Please provide 3
mgs of puriifed lyophilized antibody (or your protein) with the necessary data for
purity assessment. Commercial available biopolymers can be supplied by customers
or synthesize or ordered through Bio-Synthesis.
Gold Conjugate Service Descriptions
Price: Price varied based on project specifications. Price does
not includes cost of small molecule or biopolymer which requireed to be supplied
by customer or order through Bio-Synthesis from a commercial vendor. Some of the
small molecules are commerically available in an activated form. For non-active
molecules, Bio-Synthesis can assit with the design and, if deemed necessary, biopolymer
modification to introduce additional functional groups and extra linkers.
Please contact us for a quote.
Protein/Antibody-Gold Nanoparticles Conjugation
Due to variations in affinity between diferrent proteins and the gold nanoparticle
surface, there is no guaranteed final volume of product. An average yield of 10
ml of your protein-gold nanoparticle conjugate is 3 ODs. This amound woudl be enough
to be probe 100 dot blot strps using 15 ml of a 1:100 diluted conjugate per strip.
Oligonucleotide-Gold Nanoparticle Conjugation
Oligonucleotide length and sequence might influence final yield of gold nanoparticle
conjugates, an average yield is 1 OD in 30 ml of oligonucleotide-gold conjugates.
Coupling of preactivated small molecule and biomolecule
with chemical reactive groups such as Amine reaction with NHS or other active esters.
Sulfhydryl reaction with maleimide or alkyl halide containing compounds.
After standard desalting, or purification,
a small percent of heterogeneous products containing single or multi-site conjugate
per molecule may exist.
nanogold, undecagold or colloidal gold size of your choice
After labeling, final conjugates must first be isolated
from excess or unreacted reagent by gel filtration or dialysis. In many cases, simple
dialysis may suffice to remove unreacted reagent from the reaction solution. Additional
purification technique such as gel filtration chromatography may also be used to
either remove excess reagent or isolate and characterized the cross-linked product.
With exception of dialysis, if the protein/antibody is significantly larger (>3-fold)
than the modifying or coupling reagent. For reagents (mostly protein and other biological
molecules) that are similar in size or larger than the antibody, one must resort
to other purification techniques such as affinity chromatography, ion-exchange chromatography,
and hydrophobic interaction chromatography.
The conjugates were characterized using UV–visible (UV/Vis) absorption spectroscopy.
Transmission electron microscopy (TEM) and dynamic light scattering (DLS and the
biological activities of the conjugated products were also assessed using an immunoassay
format and electrochemical measurements with an additional fee.
Ordering and Submitting Requests for Bioconjugation Services
For us to better understand your customized project, please complete our Bioconjugation Service Questionnaire. The more our chemists understand your project’s needs, the more accurate your provided feedback will be. Providing us with your project’s details enables us to recommend the best reagents to use for your project. The most useful and readily available tools for bioconjugation projects are cross-linking reagents. A large number of cross-linkers, also known as bifunctional reagents, have been developed. There are several ways to classify the cross-linkers, such as the type of reactive group, hydrophobicity or hydrophilicity and the length of the spacer between reactive groups. Other factors to consider are whether the two reactive groups are the same or different (i.e. heterobifunctional or homobifunctional reagents), spacer is cleavable and if reagents are membrane permeable or impermeable. The most accessible and abundant reactive groups in proteins are the ϵ-amino groups of lysine. Therefore, a large number of the most common cross-linkers are amino selective reagents, such as imidoesters, sulfo-N-hydroxysuccinimide esters and N-hydroxysuccinimide esters. Due to the high reactivity of the thiol group with N-ethylmaleimide, iodoacetate and a-halocarbonyl compounds, new cross-linkers have been developed containing maleimide and a-carbonyl moieties. Usually, N-alkylmaleimides are more stable than their N-aryl counterparts.
In addition to the reactive groups on the cross-linkers, a wide variety of connectors and spacer arms have also been developed. The nature and length of the spacer arm play an important role in the functionality. Longer spacer arms are generally more effective when coupling large proteins or those with sterically protected reactive side-chains. Other important considerations are the hydrophobicity, hydrophilicity and the conformational flexibility. Long aliphatic chains generally fold on themselves when in an aqueous environment, making the actual distance spanned by such linker arms less than expected. Instead, spacers containing more rigid structures (for example, aromatic groups or cycloalkanes) should be used. These structures, however, tend to be very hydrophobic which could significantly decrease the solubility of the modified molecules or even modify some of their properties. In such cases, it is recommended to choose a spacer that contains an alkyl ether (PEO) chain. Bio-Synthesis offers several cross-linkers with PEO chains, such as thiol-binding homobifunctional reagents, heterobifunctional bases and their derivatives.
Within 3-5 days upon receiving your project scope, we will provide you an appropriate quotation. An order can be placed with PO (Purchase Order) or major credit cards ( ). Your credit card will be billed under Bio-Synthesis, Inc.