Efficient strategies for the conjugation of oligonucleotides to antibodies enabling highly sensitive protein detection

Abstract

Three methods for the conjugation of oligonucleotides to antibodies and the subsequent application of these conjugates to protein detection at attomole levels in immunoassays are described. The methods are based on chemical modification of both antibody and oligonucleotide. Aldehydes were introduced onto antibodies by modification of primary amines or oxidation of carbohydrate residues. Aldehyde- or hydrazine-modified oligonucleotides were prepared either during phosphoramidite synthesis or by post-synthesis derivatization. Conjugation between the modified oligonucleotide and antibody resulted in the formation of a hydrazone bond that proved to be stable over long periods of time under physiological conditions. The binding activity of each antibody-oligonucleotide conjugate was determined to be comparable to the corresponding unmodified antibody using a standard sandwich ELISA. Each oligonucleotide contained a unique DNA sequence flanked by universal primers at both ends and was assigned to a specific antibody. Highly sensitive immunoassays were performed by immobilizing analyte for each conjugate onto a solid support with cognate capture antibodies. Binding of the antibody-oligonucleotide conjugate to the immobilized analyte allowed for amplification of the attached DNA. Products of amplification were visualized using gel electrophoresis, thus denoting the presence of bound analyte. The preferred conjugation method was used to generate a set of antibody-oligonucleotide conjugates suitable for high-sensitivity protein detection.

Novel Biosensor–Based Analytic Device for the Detection of Anti–Double-Stranded DNA Antibodies

“…We used aldehyde and hydrazine chemistry for this conjugation (20 ). hTf was used in excess to prevent high losses of CHO-ODN and formation of poorly defined side products.…”

Functionalization of Block Copolymer Vesicle Surfaces

“…Using two complementary hetero-bifunctional linkers confers the further advantage that cross-linking cannot occur. Such a system was used to specifically and quantitatively conjugate oligonucleotides to antibodies [63] and to bind proteins to other proteins [64] in aqueous solution. Because this conjugation reaction is carried out under mild conditions in aqueous buffer, without any additional catalyzing agents (e.g., in contrast to the copper catalyzed azide-alkyne click reaction), the resulting conjugates are applicable for pharmaceutical and therapeutic purposes.…”

Immunotherapeutic activity of a conjugate of a Toll-like receptor 7 ligand

“…2). Initially, the amino groups on MSA derivatized with SANH according to standard procedures (18). To remove excess SANH, the reaction mixture was loaded on a NAP-10 column equilibrated with PBS and eluted with PBS.…”