materialsresearch

Structural Elucidation of Citric Acid Cross-Linked Pectin and Its Impact on the Properties of Nanocellulose-Reinforced Packaging Films

Citric acid cross-linking is an effective strategy for modifying citrus pectin to enhance its performance in sustainable packaging applications. In this article, Chandra Mohan Chandrasekar, Daniele Carullo, Francesco Saitta, Tommaso Bellesia, Elena Caneva, Chiara Baschieri, Marco Signorelli, Dimitrios Fessas, Stefano Farris and Davide Romano, investigated the structural changes induced by citric acid cross-linking and their influence on the properties of nanocellulose-reinforced packaging films..

The authors demonstrated that cross-linking significantly alters the structure–property relationship of the biopolymer matrix, leading to improved film integrity and modified surface morphology. These results provide valuable insight into biopolymer modification strategies for the development of environmentally friendly packaging materials.

Atomic force microscopy (AFM) was employed to characterize the surface morphology of the films. Measurements were performed using a commercially available AFM instrument operated in contact resonance amplitude imaging (CRAI) mode. A NanoWorld Arrow-FMR AFM probe was used.

This AFM probe features a rectangular beam with a triangular free end and a tetrahedral tip (tip radius ~10 nm, tip height 10–15 μm), with a spring constant of 2.8 N/m and a resonance frequency of 75 kHz. Root mean square surface roughness values were calculated from at least five height-mode images.

Fig. 3. 2D synchronized correlation analysis of FTIR spectra for CLCP packaging film trials. [The intensity of the auto-peaks on the diagonal line represents the overall change in spectral intensity. The key region of interest is the strong auto-peak around 1700 cm−1, highlighted by

Full citation: Chandrasekar, C. M.; Carullo, D.; Saitta, F.; Bellesia, T.; Caneva, E.; Baschieri, C.; Signorelli, M.; Fessas, D.; Farris, S.; Romano, D. “Structural elucidation of citric acid cross-linked pectin and its impact on the properties of nanocellulose-reinforced packaging films.” International Journal of Biological Macromolecules 2025, 333(2), 148869. https://doi.org/10.1016/j.ijbiomac.2025.148869

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Nonlinear Optical Response in Layer-Stacked Gallenene with Ferroelectric Polarization

Layer-stacked gallenene is an emerging two-dimensional material with unique structural and electronic propertiesIn this article, M.Yunusa, A. K.Schulz, T.Parker, et al. investigated the nonlinear optical response of layer-stacked gallenene exhibiting ferroelectric polarization. The material was produced using a liquid metal-based synthesis approach and showed a phase transition associated with its stacked structure.

The authors demonstrated strong second harmonic generation (SHG) signals, revealing the nonlinear optical activity of gallenene and confirming its ferroelectric nature. These findings highlight the potential of gallenene as a novel functional 2D material for advanced optoelectronic and photonic applications.

Atomic force microscopy (AFM) was used to characterize transparent lamellar films and helical filaments. Measurements were performed using a commercially available AFM instrument operated in contact mode. A NanoWorld Arrow-CONTR AFM probe with a nominal force constant of 0.2 N/m and a resonance frequency of 14 kHz was used to obtain high-resolution surface morphology data.

*Figure 1*
Structure of gallenene and complex anatomy of supercooled liquid gallium. Mechanism for electrical and thermal perturbation. a) Illustration of hypothesized interaction of SHG response with SLG in linearly polarized light showing that thermal perturbations could align the 2D nanocrystals, allowing for an increased SHG medium at either temperature or electrical fields. An example HAADF image of gallenene flake sandwiched between two graphene layers, as depicted in (a) (far right microscope image). b) Structural reorganization of gallenene nanocrystals in the SLG leading to an intensity change in SHG signal as a result of thermal or electrical perturbation.

Full citation:

Yunusa, M.; Schulz, A. K.; Parker, T.; Schneider, F.; Elibol, K.; Predel, M.; Dzíbelová, J.; Rebmann, M.; Gorkan, T.; Ye, J.; Tan, J.-C.; Kang, W.; van Aken, P. A.; Meixner, A. J.; Durgun, E.; Kotakoski, J.; Zhang, D.; Sitti, M. Nonlinear Optical Response in Layer-Stacked Gallenene with Ferroelectric Polarization.

Advanced Materials 2025, 37(44), e01058.

https://doi.org/10.1002/adma.202501058

NanoWorld at MRS Fall Meeting & Exhibit 2024 this week

NanoWorld CEO Manfred Detterbeck is in Boston for the MRS Fall 2024 Meeting & Exhibit this week.
You’ll meet him at some of the sessions or at NanoAndMore USA booth no. 402.

If you’re there too feel free to say hi and have a chat about #AFMprobes with him.

Happy to be at MRS Fall 2024. Hope to see many of you here.