A bottlebrush polymer from Northeastern carries its own tissue-targeting sequence for oligonucleotide drugs
Northeastern's Ke Zhang reports a bottlebrush polymer with a built-in sequence meant to steer oligonucleotide drugs to particular tissues. "Knowing what gene to target is only part of the problem," Zhang said, and delivery to the right cells is the rest.
The Scientist · Science desk
Kidney filtration threatens oligonucleotides in the bloodstream; bottlebrush bristles add bulk against it. Cell membranes keep intruders out, AstraZeneca's Dahlen says. Antibody targeting is limited by shared or missing receptors. A built-in sequence steers the drug toward tissues.
- constraint Kidney filtration Threatens to make short work of oligonucleotides as soon as they are in the bloodstream, claim 7
- capability Bottlebrush bristles Protect the attached drug and add bulk, making it harder for the kidneys to filter it out, claim 8
- constraint Cell membranes Evolved to keep intruders out; oligonucleotides struggle to get through, AstraZeneca's Dahlen says, claim 5
- constraint Antibody targeting A receptor may sit on several cell types; some cells lack the binding machinery or a unique receptor, claim 10
- capability Bottlebrush sequence A short built-in sequence of building blocks steers the medicine toward particular tissues, claim 4
| Who | How | Kind | Claim |
|---|---|---|---|
| Kidney filtration | Threatens to make short work of oligonucleotides as soon as they are in the bloodstream | constraint | 7 |
| Bottlebrush bristles | Protect the attached drug and add bulk, making it harder for the kidneys to filter it out | capability | 8 |
| Cell membranes | Evolved to keep intruders out; oligonucleotides struggle to get through, AstraZeneca's Dahlen says | constraint | 5 |
| Antibody targeting | A receptor may sit on several cell types; some cells lack the binding machinery or a unique receptor | constraint | 10 |
| Bottlebrush sequence | A short built-in sequence of building blocks steers the medicine toward particular tissues | capability | 4 |
What happened
- Most drugs act on finished proteins, but oligonucleotides intervene upstream, blocking harmful proteins from being made or helping cells make needed ones by altering the instructions.
- Kidney filtration threatens oligonucleotides as soon as they reach the bloodstream, so a carrier has to keep them circulating before targeting can matter.
- Antibody targeting has limits: one receptor can sit on several cell types, and some cells lack the binding machinery or any receptor unique enough to use.
- AstraZeneca's Anders Dahlen told Northeastern Global News that cell membranes evolved to keep intruders out, and large, negatively charged molecules such as oligonucleotides struggle to cross.
Why it matters
- capability If a sequence in the packaging can steer a drug, targeting would no longer depend on a cell carrying a receptor unique enough for an antibody to lock onto.
- contradiction Zhang frames the problem as reaching the right cells, but the bias he describes is toward organs and tissues, a coarser level; a gene active in several cell types within one organ would still need more.
- precedent If the packaging can carry tissue information, developers would be able to vary the carrier independently of the drug's own genetic sequence.
Scientists have tried tucking oligonucleotides into tiny fat particles, injecting them close to their destination and changing their chemistry to help cells take them up [6]. Zhang's approach is a polymer carrier, with the drug attached to a backbone ringed by densely packed branches [8].
What the bottlebrush adds, in Zhang's telling, is information in the packaging. "We found that the packaging itself actually can contain information that allows the drug to be biased toward different organs and tissues," Zhang said [11]. An antibody finds its target by binding a receptor on the cell [9]. The polymer carries its address with it [4].
In our view this is a sound thing to test, with one condition on how it is tested. The bottlebrush does two jobs at once. Its bulk makes the package harder for the kidneys to filter out [8], and its short sequence is meant to steer it [4]. Longer circulation alone could change where a drug ends up, so a distribution pattern from the full construct would not show that the sequence is responsible. The matched control is the same polymer without the sequence.
The thing this doesn't tell you is whether that comparison was run. The phys.org write-up, in the portion available, does not say which tissues were examined, in what model, or how much drug arrived [3].
The write-up's own framing is conditional. The Journal of the American Chemical Society paper presents research that "suggests" a new way to get oligonucleotides into body tissues [3], and the write-up says the approach "could unlock their potential to tackle diseases that are currently untreatable" [12].
What to watch
- The JACS paper's biodistribution data: which tissues were reached, in what model, and how the full polymer compares with the same polymer lacking the targeting sequence.
- Whether the tissue bias holds at the level of individual cell types, which is how Zhang states the delivery problem.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence50
- Adoption
- Insufficient
- Hype gap+35
- Incentives
- Insufficient
- Confidence55
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
Most drugs act on finished proteins, but oligonucleotides intervene upstream, before proteins are made. They can block production of harmful proteins or help cells make ones they need by altering the instructions.
- [2]
"Knowing what gene to target is only part of the problem," said Northeastern chemistry and chemical biology professor Ke Zhang. "The other part is getting the drug to the right place in the right cells."
- [3]
In the Journal of the American Chemical Society, Zhang and his colleagues present research that suggests a new way to get oligonucleotides into body tissues.
- [4]
The delivery structures resemble tiny bottlebrushes with protective bristles, and a short sequence of chemical building blocks incorporated into the structure acts as a set of delivery instructions to steer the medicine toward particular tissues.
- [5]
Anders Dahlen, senior director of oligonucleotides and targeted delivery at AstraZeneca, told Northeastern Global News that cell membranes have evolved to keep intruders out, and large, negatively charged molecules such as oligonucleotides have a particularly hard time getting through.
- [6]
Scientists have tried tucking oligonucleotide drugs into tiny fat particles, injecting them close to their destination, or changing their chemistry to help cells gobble them up.
- [7]
The kidneys' filtration system threatens to make short work of oligonucleotides as soon as they are in the bloodstream.
- [8]
The bottlebrush polymers have a central polymer backbone surrounded by densely packed branches that look like bristles. They protect the attached drug and add bulk, which makes it harder for the kidneys to filter the package out.
- [9]
One way to deliver oligonucleotide drugs to the right cells is to attach them to an antibody, which binds a specific receptor on a target cell like a key in a lock.
- [10]
The antibody lock-and-key approach can be tricky: the same receptor may appear on several cell types, not all cells have the molecular machinery for this type of binding, and sometimes cells have no receptor unique enough to pair with a specific key.
- [11]
"We found that the packaging itself actually can contain information that allows the drug to be biased toward different organs and tissues," Zhang said.
- [12]
The write-up states that by helping genetic medicines reach their target, this approach could unlock their potential to tackle diseases that are currently untreatable.
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Sources
1 independent publisher whose own reporting we read for this story.
- phys.orgCould a molecular ZIP code unlock treatments for untreatable diseases?
1 article · October 14, 2026
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