Dual Location, Dual Acidic pH/Reduction-Responsive Degradable Block Copolymer: Synthesis and Investigation of Ketal Linkage Instability under ATRP Conditions
Bibliographic record
Abstract
Stimuli-responsive degradation (SRD) undergoing chemical transition through the cleavage of labile linkages has been proved to dramatically increase the versatility of stimuli-responsive block copolymers. In particular, dual or multiple stimuli-responsive degradable block copolymers that can be triggered by two endogenous stimuli of acidic pH and reduction are in high demand. Here, a new strategy utilizing atom transfer radical polymerization (ATRP) is reported to synthesize a dual acidic pH/reduction-responsive degradable block copolymer (DLDSRD) labeled with an acidic pH-labile ketal linkage at the block junction and pendant reductively cleavable disulfide groups in hydrophobic block at dual locations. A robust route with multiple steps utilizing carbamate chemistry to endow stability during protection/deprotection steps enables the synthesis of a novel poly(ethylene glycol)-based ATRP macroinitiator labeled with a ketal linkage (PEG-ketal-Br macroinitiator). Conducting ATRP allows for the synthesis of a series of DLDSRD diblock copolymers consisting of a hydrophilic poly(ethylene glycol) block covalently conjugated through a ketal linkage with a hydrophobic polymethacrylate block having multiple disulfide pendants. Analysis shows an unexpectedly high degree of polymerization of the hydrophobic polymethacrylate block that could be attributed to the instability of ketal linkages under ATRP conditions. The preliminary results from aqueous micellization and dual acidic pH/reduction-responsive cleavage of ketal and disulfide linkages suggest the feasibility of DLDSRD-based nanoassemblies toward effective drug delivery exhibiting precisely controlled release in response to dual stimuli at dual locations (core and interfaces).
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".