Editors Raise Concerns Over Pectin Hydrogel Study for Nifedipine Delivery

A scientific publishing drama has unfolded in the pages of Polymer Bulletin, where the Editor-in-Chief has issued an Editorial Expression of Concern over a 2019 study that promised an elegant solution to one of pharmaceutics’ most persistent challenges: delivering the blood pressure drug nifedipine in a controlled, predictable manner. The notice, published on 7 September 2026 as volume 83, article number 629 of the journal, alerts readers that serious questions have been raised about the integrity of data presented in the original paper, which described pectin-based hydrogels engineered with adjustable properties for the controlled release of the antihypertensive compound. The expression of concern stops short of retraction, but it places a cloud over findings that had been part of a growing body of literature on natural polymer drug delivery systems.

The original article, published on 17 December 2019 in Polymer Bulletin volume 77, pages 6063 to 6083, reported the development and optimization of hydrogel networks built from pectin, a naturally occurring polysaccharide most familiar to consumers as the gelling agent in jams and jellies. In pharmaceutical science, pectin has attracted intense interest because it is biocompatible, biodegradable, inexpensive, and derived from renewable plant sources such as citrus peel and apple pomace. The research team, led by authors affiliated with Government College University Faisalabad, the University of Sargodha, The University of Lahore, and The Islamia University of Bahawalpur in Pakistan, set out to tune the swelling behavior, gel fraction, and drug release kinetics of these hydrogels so that nifedipine could be released steadily over an extended period rather than in a sudden burst.

Nifedipine is a calcium channel blocker widely prescribed for hypertension and angina, and its delivery profile matters enormously for patient safety. The drug is notoriously photolabile and poorly water soluble, and conventional immediate-release formulations have been associated with sharp drops in blood pressure and reflex tachycardia. Controlled-release matrices, including hydrogel systems, are designed to smooth out these peaks and troughs by allowing water to penetrate the polymer network, dissolve the drug, and then diffuse outward through the swollen mesh at a rate governed by crosslinking density, polymer composition, and mesh size. A pectin-based system with adjustable properties would, in principle, let formulators dial in the desired release rate simply by changing formulation variables, a proposition with genuine commercial and clinical appeal.

That is precisely why the concerns flagged by the Editor-in-Chief strike at the heart of the paper’s credibility. According to the expression of concern, Figure 5 of the pectin hydrogel article appears to be identical to Figure 2c in a separate 2018 publication on chondroitin sulfate-based hydrogels of loxoprofen, which appeared in Carbohydrate Polymers. The overlap involves two different polymers, two different drugs, and two different experimental contexts, making the apparent duplication particularly troubling. In materials characterization, figures typically present spectroscopic traces, swelling curves, or release profiles that are unique to a specific formulation under specific conditions. When the same figure surfaces in studies of unrelated polymer-drug combinations, it raises the possibility that the underlying experiments were not performed as described, or that images were reused to fill gaps in the data record.

The second concern is subtler but no less consequential. The Editor-in-Chief notes that the acrylic acid trace in Figure 2 of the pectin study appears highly similar to the trace in Figure 2 of yet another 2018 paper, this one describing a cross-linked sodium alginate-g-poly(acrylic acid) hydrogel network for the delivery of loxoprofen sodium, published in Advanced Polymer Technology. In that case, the similarity persists even though the x-axis appears to have been shifted slightly. Fourier transform infrared spectroscopy and related analytical traces are fingerprints of chemical structure, and while spectra of related acrylate-based networks can resemble one another, a near-duplicate trace with a minor axis shift suggests digital manipulation rather than independent measurement. Shifting an x-axis is a classic red flag in image-integrity investigations because it can make copied data look superficially distinct while preserving the underlying pattern.

Compounding these figure-level concerns is the authors’ response, or lack thereof. The expression of concern states that the authors have not provided the original scanning electron microscopy images, both before and after expansion, upon request. SEM micrographs are central evidence in hydrogel characterization, revealing pore morphology and network structure that correlate directly with swelling and diffusion behavior. When authors cannot or will not produce the raw image files underlying published micrographs, editors and readers lose the ability to verify that the images depict the samples in question. The notice also records that the authors have not responded to any correspondence from the editor or publisher regarding the expression of concern, leaving the issues unresolved and the scientific record in limbo.

Editorial Expressions of Concern occupy an important and often misunderstood niche in scholarly publishing. Unlike a retraction, which withdraws a paper’s findings from the literature, an expression of concern signals that doubts exist but that an investigation is incomplete, inconclusive, or ongoing. Journals typically issue them when institutional inquiries are pending, when authors are unresponsive, or when the evidence of problems is strong but not yet definitive. Readers are advised in this case to interpret the results with caution, which in practical terms means that researchers citing the paper should acknowledge its contested status and that clinicians or formulators should not rely on its reported optimization data without independent confirmation. The notice is linked to the original article through Crossmark, Springer Nature’s version-of-record update service, ensuring that anyone accessing the 2019 paper will see the alert.

The episode also shines a light on the broader challenge of image integrity in polymer and pharmaceutical sciences, fields that generate enormous volumes of spectroscopic traces, micrographs, and kinetic curves. Duplicate and manipulated figures have been documented across disciplines, and automated screening tools now routinely flag similarities that might once have escaped notice. The two earlier papers referenced in the expression of concern, both involving overlapping authorship with the pectin study, illustrate how concerns can cluster around related bodies of work. When a single figure or trace appears in multiple publications describing different chemical systems, the credibility of all affected papers comes into question, because at least some of the published data cannot reflect real experiments as described.

For the field of natural polymer drug delivery, the stakes extend beyond one paper. Pectin, alginate, chondroitin sulfate, and related polysaccharides remain genuinely promising scaffolds for controlled release, and well-executed studies continue to advance the area. But the credibility of that literature depends on the verifiability of individual results, and expressions of concern like this one serve as a reminder that optimization claims, release profiles, and structural characterizations must rest on data that can withstand scrutiny. Whether the 2019 pectin-nifedipine study is ultimately retracted, corrected, or exonerated, the case underscores a simple principle on which the entire enterprise of pharmaceutical materials science depends: the figures in a paper must be the honest record of the experiments the paper claims to describe.

Subject of Research: An Editorial Expression of Concern raised over a pectin-based hydrogel study for controlled nifedipine delivery in Polymer Bulletin

Article Title: Editorial Expression of Concern (EEoC): Pectin-based hydrogels with adjustable properties for controlled delivery of nifedipine: development and optimization

Article References: Editorial Expression of Concern (EEoC): Pectin-based hydrogels with adjustable properties for controlled delivery of nifedipine: development and optimization. (n.d.). https://doi.org/10.1007/s00289-026-06680-3

Image Credits: AI Generated

DOI: 10.1007/s00289-026-06680-3

Keywords: pectin hydrogels, nifedipine, controlled drug delivery, Editorial Expression of Concern, Polymer Bulletin, research integrity, image duplication, scanning electron microscopy, polysaccharide polymers, drug release kinetics, Springer Nature, pharmaceutics