Dendritic Bioconjugation Services

Service Descriptions

Price

Price varies based on the proejct specifications. Our service includes materials and labor for conjugation only! Price does not include the cost of biopolymer synthesis and, if deemed necessary, biopolymer modification to introduce additional functional groups, extra linkers, spacers. Please contact us for a quote.

Chemistry:

Coupling of preactivated small molecule and biomolecule with chemical reactive groups such as amine, thiol, carboxylate, hydroxyl, aldehyde and ketone, active hydrogen through use of varous cross linkers.

Nanomaterials

• liAMAM-liEG Dendrimer
• Dendrons
• liAMAM Dendrimers (G0 through G10)
• liolyliroliylenimine Dendrimers

Biopolymer

• Protein: Enzyme, antibodies, antigens, cell adhesion molecules
• Peptides: Synthetic polypeptides
• Saccharides: Sugars, oligosaccharides and polysaccharides
• Lipids: Fatty acids, phospholipids, glycolipids, Myristic acid, Palmitic acid, Stearic acid and any fat-like substances.
• Ligands: Hormone receptors, cell surface receptors, avidin and biotin, small molecules
• Nucleic acids and nucleotides: DNA, RNA, PNA, nucleic acid analogs and genomic DNA

Service Specification:

After standard desalting, or purification, a small percent of heterogeneous products containing single or multi-site conjugate per molecule may exist.

Procedure:

After labeling , final conjugates must first be isolated from excess or unreacted reagent by gel filtration or dialysis with a matrix having an exclusion limit appropriate to accommodate the size of the molecules being separated.

Cross-linked target molecule may then be further characterized by gel electrophoresis. It may be subject to additional analyses with an addtional fee. This including spectroscopic (MALDI-TOF, ESI, LC-MS Fluorescence), electrophoresis, immunochemical biochemical, enzymatical analysis, TLC. QC (quality control) and QA (quality assurance) procedures are also followed independently to offer you double guarantee for the highest quality possible of every delivered conjugates. Moreover, our dedicated technical account managers will guide your project through every step of the process and constantly keep you informed of the latest project progress.

To obtain further information regarding custom dendrimer or dendron bioconjugation, contact our National Customer Services Center at 800.227.0627 or contact us online with each inquiry to assist in meeting customer specifications.

Dendrimer-oligonucleotide conjugation

Dendrimers are discrete, highly branched, monodispersed polymers with three disctinct structureal features: a central core surface functionalities and branching units that link the two. Plain and mixed oligonucleotide dendrimers can be synthesized using novel doubling and trebling phosphoramidite synthons.1,2 Dendrimers offer the following advantages. Incorporation of label using γ-32P-ATP and polynucleotide kinase increases in proportion to the number of 5’-ends. Fluorescent signal also increases in proportion to the number of 5’-ends, if spacers are incorporated between the labels and the ends of the branches. When using a dendrimeric oligonucleotide as a PCR primer, the strand bearing the dendrimer is resistant to degradation by T7 Gene 6 exonuclease making it easy to convert the double-stranded product of the PCR to a multiply labelled, single-stranded probe. Enhanced stability of DNA dendrimers makes them useful as building blocks for the ‘bottom up’ approach to nano-assembly. These features also suggest applications in DNA chip technology when higher temperatures are required, for example, to melt secondary structure in the target.

Can't find type of service you need? don't worry, as you can see we've provided myriad of bioconjugation services as described in our service portfolios and much more, just contact our National Customer Service Center at 800.220.0627 or contact us online with your detail project descriptions, in most case, we can accommodate your bioconguateion needs!

Peptide Dendrimers as Protein Mimetics

Peptide dendrimers are radial or wedge-like branched macromolecules consisting of a peptidyl branching core and/or covalently attached surface functional units. The multimeric nature of these constructs, the unambiguous composition and ease of production make this type of dendrimer well suited to various biotechnological and biochemical applications. Diagnostic and biochemical uses of peptide dendrimers in four active areas of research:

• Biochemical studies: affinity purification, as immunogens and antigens;
• De novo design of artificial porteins;
• Protein mimetics, as agonists and antagonists in drug discovery
• Vehicles for delivery of nucleic acids, drugs, vaccine
• New biopolymers and biomaterials.

Peptide dendrimers vary from low molecular weight species of 2 kDa to large protein-like constructs 100 kDa. The size and complexity of the inliidual dendrimers are determined by two factors, the number of layers of branching units (often referred to as the generation number) and the surface supporting the terminal functional groups which can be large peptides or proteins of substantial size. Typically, peptide dendrimers have generation numbers between 2 and 32. Similarto other dendrimers, synthesis of peptide dendrimers is tightly controlled with products of consistent size, architecture and composition.

Peptide dendrimers maybe be placed into three categories.The first are grafted peptide dendrimers. These are conventional dendrimers with either unnatural amino acids or organic groups as the branching core and peptide or proteins attached as surface functional groups. Of the three, the grafted peptide dendrimer is the largest in terms of size because they generally contain high generation numbers of branching cores. In contrast, peptide dendrimers of the second type are essentially branching polyamino acids. Consequently, they tend to be the smallest by size with the core consisting of natural amino acids and the terminal amino acids acting as surface functional groups. The third type consisting of mostly peptides has been traditionally known as peptide dendrimers. In this group, with MAPs as the most well known example, the core consists of amino acids and the surface functional groups are also peptidyl chains

MAP Dendrimer Peptide Constructs

Multiple antigenic (MAP) peptide dendrimers are branched polymers with peptides attached centrally to a dendritic lysine arms or core matrix and a surface of peptide chanins attached to the core matrix. They are synthesized as defined dendritic structures using two methods 1) direct standard solid-phase (Fmoc) chemistry; 2) indirect approach in which peptide an dcore matrix are synthesized separately and conjugated by several ligation methods. Their molecular weights increase geometrically as a function of generation branching of monomers. Usually, two to sixteen peptidyl branches of the same or different sequences are used to form a peptide dendrimer, resulting three dimensional molecule which has a high molar ratio of peptide antigen to core molecule, and therefore, does not require the use of a carrier protein to induce an antibody response. These high molar ratio and dense packing of multiple copies of the antigenic epitope in a MAP has been use to promote immunoresponse. In addition to the applications in immunology, examples in the literature have applied MAPs in areas such as inhibitors, artificial proteins, affinity purifications, and intracellular transport.

The MAP, which is chemically defined and homogeneous, was first intended as a means for overcoming the limitations of the conventional method for producing anti-peptide antibodies. In the conventional approach, the peptide antigen is conjugated to a known large protein, or synthetic polymer carrier, to form a peptide-carrier conjugate. Although this strategy has been used successfully in eliciting animal antibodies, it has several inherent limitations. First, only a small portion of peptide antigen is represented in the whole conjugate; second, there is chemical ambiguity in the antigen composition and structure; third, irrelevant epitopes and antibodies may be produced; and finally, carrier toxicity and carrier-induced epitope suppression may occur. The MAP systems have been used successfully to produce both polyclonal and monoclonal antibodies that specifically recognize native proteins. They have also been used to produce sera that have a significantly higher titer of antibodies than sera with antibodies against the same peptides conjugated to the commonly used carrier protein keyhole limpet hemocyanin (KLH; Tam, 1988).

PAMAM Dendrimer Peptide Constructs

grafted peptide dendrimer with unnatural amino acids and organic poly(amidoamine), or PAMAM core, is perhaps the most well known dendrimer. The core of PAMAM is a diamine (commonly ethylenediamine), which is reacted with methyl acrylate , and then another ethylenediamine to make the generation-0 (G-0) PAMAM. Successive reactions create higher generations, which tend to have different properties. Lower generations can be thought of as flexible molecules with no appreciable inner regions, while medium sized (G-3 or G-4) do have internal space that is essentially separated from the outer shell of the dendrimer. Very large (G-7 and greater) dendrimers can be thought of more like solid particles with very dense surfaces due to the structure of their outer shell. Peptide can be attached through the functional group on the surface of PAMAM dendrimers which gives rise to many potential applications.

Bio-Synthesis offer Peptide-PAMAM dendrimer synthesis with various core types and generations. contact our National Customer Service Center at 800.220.0627 or contact us online with your detail project descriptions, in most case, we can accommodate your bioconguateion needs!

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.