Redefining what is possible in controlling monomer sequences.



Exactmer has exclusive rights to the patented Nanostar Sieving technology, which allows synthesis of exact polymers in liquid phase.

There is increasing interest in using biopolymers such as oligonucleotides to develop new therapies for a wide range of currently untreatable diseases. These polymers are mostly prepared by solid-state synthesis, resulting in very poor scaling capabilities, low final purity and high prices. This means that the promising development of new therapies is currently limited by the high cost of manufacture - we believe Exactmer can help to solve this problem.

The technology comprises a coupling reaction in which multiple growing polymer chains are attached to a central hub molecule to create a “nanostar” with enhanced molecular size. Each monomer is added to the polymer chains iteratively, until the exact polymer sequence is achieved. At each iteration the growing polymer is effectively purified by removing the reaction debris via purpose-designed nanomembrane filtration, until the final polymer is produced.

We are planning to operate our technology in a GMP (Good Manufacturing Practice) facility by the end of 2023.


Our technology has unique advantages compared to conventional methods of polymer production via solid phase synthesis:

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Longer polymers

In liquid phase there is no limit imposed on the molecular weight of obtained polymers, unlike the steric confines of solid phase synthesis.

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The process is completely liquid phase and therefore scalable to the ton scale.

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Lower costs and higher purity

Because the growing polymer is in liquid phase it is possible to validate that each coupling reaction has gone to completion in each step, reducing error sequences and the need for expensive final chromatography, leading to higher purity polymers and lower production costs.


Exactmer is able to produce polymers of unprecedented precision and length using Nanostar Sieving. Our polymers have a wide range of possible applications:

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Our unique polymers can be used to develop new oligonucleotide therapies and they can be attached to bioactive molecules (PEGylation process) to improve their efficiency and safety in patients.

Oligonucleotide market +
PEGylated drug market +
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Drug Delivery

Our PEG polymers can undergo site-selective modification leading to the formation of sequence-defined multifunctional polymers with potential applications as biomedical vehicles and in the development of antibody-drug conjugates.

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Our polymers are potentially compatible to be assembled to a variety of nanomaterials (nanotubes, vesicle, nanofibers, etc.) and can potentially be used for information storage.