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Services

AM Chemicals offers services in expert synthesis of ¹⁴C, ³⁵S, and ³H radiolabeled oligonucleotides and their phosphorothioate analogs. We synthesize radiolabeled, protected nucleoside phosphoramidite reagents required for the incorporation of the desired radiolabels into oligonucleotides, carry out oligo synthesis, deprotect, purify, and desalt the target radiolabeled oligonucleotides (specifications set by the customers).

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Custom Radiolabeling of Synthetic Oligonucleotides

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Synthesis of ¹⁴C, ³⁵S, and ³H radiolabeled oligonucleotides and their phosphorothioate analogs (1 to 100 µmol of isolated product) 

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  • Synthesis of [¹⁴C]-and [³H]-labeled, protected nucleoside phosphoramidite building blocks

  • Synthesis of the target radiolabeled oligonucleotides

  • Purification by reverse-phase or ion-exchange HPLC as requested by customer and desalting

  • For siRNA, forming a duplex by hybridization with the unlabeled strand

  • Optionally, confirmation of structure by ES MS

  • Optionally, removal of endotoxin from the final product

  • Optionally, performing above operations under GMP conditions

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Custom Quote

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To request the custom quote, please furnish the following information:

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  • Oligonucleotide sequence

  • Desired radioisotope (¹⁴C, ³⁵S, and ³H)

  • Placement of the radiolabeled nucleoside in the sequence

  • Desired specific activity (SA):

    • A single labeling affords SA of 30-40, 100-400, and 500-1500 Ci/mol for ¹⁴C, ³⁵S, and ³H radioisotopes, respectively

  • Desired amount of radiolabel incorporated or amount of radiolabeled oligonucleotide

  • Customers’ ability to provide project-specific unlabeled phosphoramidites of modified nucleosides or non-nucleosidic moieties

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Guidelines for Optimal Cost Control of Radio-labeling Project

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  • Pick specific activity of the target oligonucleotide as low as permissible

  • Use [4-¹⁴C]-thymidine or ³⁵S as carriers of the radiolabel

  • Placement of the radiolabeled moiety: close to the 5'-terminus of the target oligonucleotide

  • Provide project-specific unlabeled phosphoramidites of nucleosides or non-nucleosidic moieties

  • For shipping, solution is a preferred physical state of the finished product (oligo)

  • Acknowledge lead time for radio-labeling project (8 to 12 weeks) and plan ahead​​​​​

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