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A lack of mechanistic understanding of nanomaterial interactions with plants and algae cell walls limits the advancement of nanotechnology-based tools for sustainable agriculture. We systematically investigated the influence of nanoparticle charge on the interactions with model cell wall surfaces built with cellulose or pectin and performed a comparative analysis with native cell walls of Arabidopsis plants and green algae (Choleochaete). The high affinity of positively charged carbon dots (CDs) (46.0 ± 3.3 mV, 4.3 ± 1.5 nm) to both model and native cell walls was dominated by the strong ionic bonding between the surface amine groups of CDs and the carboxyl groups of pectin. In contrast, these CDs formed weaker hydrogen bonding with the hydroxyl groups of cellulose model surfaces. The CDs of similar size with negative (−46.2 ± 1.1 mV, 6.6 ± 3.8 nm) or neutral (−8.6 ± 1.3 mV, 4.3 ± 1.9 nm) ζ-potentials exhibited negligible interactions with cell walls. Real-time monitoring of CD interactions with model pectin cell walls indicated higher absorption efficiency (3.4 ± 1.3 10−9) and acoustic mass density (313.3 ± 63.3 ng cm–2) for the positively charged CDs than negative and neutral counterparts (p < 0.001 and p < 0.01, respectively). The surface charge density of the positively charged CDs significantly enhanced these electrostatic interactions with cell walls, pointing to approaches to control nanoparticle binding to plant biosurfaces. Ca2+-induced cross-linking of pectin affected the initial absorption efficiency of the positively charged CD on cell wall surfaces (∼3.75 times lower) but not the accumulation of the nanoparticles on cell wall surfaces. This study developed model biosurfaces for elucidating fundamental interactions of nanomaterials with cell walls, a main barrier for nanomaterial translocation in plants and algae in the environment, and for the advancement of nanoenabled agriculture with a reduced environmental impact.
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This content will become publicly available on December 30, 2026
Multiscale Mechanics of Calcium-Mediated Reinforcement within a Pectin-Cellulose Composite via Integrated MD and Experimental Approach
Cellulose and pectin are the key components of plant primary cell walls (PCWs) responsible for their dynamic growth, as they transition from a flexible structure at early stages to a rigid unit at full growth. However, a fundamental understanding of the pectin-cellulose interface and interactions within PCW and the underlying mechanics of these materials remained a subject of debate, hindering progress in bioinspired and sustainable composite designs to meet the demands of emerging fields, from flexible robotics to regenerative medicine. This study presents a multiscale investigation into the CNC-pectin interface and the influence of calcium ion-mediated cross-links, integrating molecular dynamics (MD) simulations, supported by experimental data of molecular interactions via spectroscopic studies and bulk interactions via viscosity measurements. The MD simulations revealed cross-linking mechanisms of “zipper” and “egg-box”, both being present, depending on local composite properties and ionic concentrations, with the zipper model being the dominant mechanism by almost 10 times with relative insensitivity to Ca2+, thus providing deeper insights into the long-ongoing discussion on pectin Ca2+ interactions. The zipper model is driven by the coordination of Ca2+ with deprotonated carboxyl groups (–COO–), while the egg-box model involves both carboxyl and hydroxyl groups (–OH). The confirmation via spectroscopic studies, characterized by consistent shifts in Raman peaks of the carboxylate group, indicating the rearrangement of ester and carboxyl groups of HGA, and concentration-dependent peak enhancement trends of the hydroxyl group in the FTIR study involved in the two models validated the MD outcomes. Furthermore, MD predicted viscosity aligned with bulk properties provides a basis for the future extension of the work on quantifying interface energies. Overall, the study provides fundamental knowledge on Ca2+-mediated CNC-pectin interactions, helping to resolve reported experimental discrepancies and offering design guidelines for advanced pectin-based biocomposites.
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- Award ID(s):
- 2304788
- PAR ID:
- 10660079
- Publisher / Repository:
- ACS Publication
- Date Published:
- Journal Name:
- ACS Applied Materials & Interfaces
- ISSN:
- 1944-8244
- Subject(s) / Keyword(s):
- cellulose pectin bioinspired composite interfacial interaction molecular dynamics simulations sustainable biomaterials
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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