Direct Quantification of PEGylation for Intact Bioconjugates and Nanoparticles by the Colorimetric Barium/Iodide Assay
Bibliographic record
Abstract
Several methods are available to determine the average number of methoxy poly(ethylene glycol) (mPEG) chains grafted to a protein or peptide, referred to as the degree of PEGylation. Nevertheless, the development of simple, versatile, and multiplexable methods for determining PEGylation remains desirable. Childs and Kurfürst have respectfully reported the quantitative and qualitative use of a colored 'barium-iodide-PEG' complex for the titration of PEG in solutions and to stain PEG-containing bands on electrophoresis gels. Remarkably, this assay has yet to be employed to directly determine the extent of PEGylation of protein bioconjugates or intact nanoparticles. This study validates this assay for these purposes, via libraries of 54 mPEG-protein conjugates and 10 polymeric nanoparticles. The effect of mPEG molecular weight, terminal functional groups, and architecture were analyzed, among other parameters. Practical details and known artifacts are discussed to enhance the accuracy and reproducibility of the assay.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".