AFMカンチレバー

Plant-Growth Synchronized, Acid Phosphatase-Responsive Lignin-Based Controlled Release Phosphorus Nanofertilizers

Developing smarter fertilizer systems that deliver nutrients when and where plants need them could help improve nutrient efficiency while reducing unnecessary losses to the environment. In this article, Alice Boarino, Nicola Carrara, Joaquin Clua, Nick Zahnd, Yves Poirier, and Harm-Anton Klok present a lignin-based nanofertilizer platform designed to respond to a biological signal associated with phosphate deficiency in plants.

The researchers developed tripolyphosphate (TPP)-cross-linked lignin nanoparticles engineered to release phosphorus in response to acid phosphatase. This enzyme is upregulated by plants under phosphate-starvation conditions, providing a mechanism for synchronizing nutrient release with plant demand. The lignin/TPP nanoparticles therefore combine a biodegradable polymer-based carrier with an enzyme-responsive release mechanism rather than relying on a conventional uncontrolled release process.

The nanofertilizers were prepared from aminated lignin and tripolyphosphate through ionic gelation followed by covalent cross-linking. The resulting nanoparticles were investigated to determine their structural and functional properties and to understand how exposure to acid phosphatase affects their stability. The authors found that phosphorus release was triggered by acid phosphatase activity and occurred together with nanoparticle disintegration, demonstrating the responsiveness of the lignin-based delivery system to the targeted enzymatic stimulus.

The biological experiments further demonstrated the potential of the nanoparticles as a phosphorus source for Arabidopsis thaliana. Treatment with lignin-TPP nanoparticles suppressed the growth inhibition and molecular responses normally associated with phosphate deficiency, supporting their potential as controlled-release nanofertilizers for plant growth and development.

Atomic force microscopy (AFM) was used to characterize the morphology and size distribution of the lignin-based nanoparticles. AFM imaging was performed in tapping mode using a NanoWorld PointProbe® NCSTR-50 AFM probe, an aluminum-coated silicon cantilever with a spring constant of 7.4 N/m and a resonance frequency of approximately 160 kHz.

For AFM analysis, nanoparticle dispersions were deposited onto cleaned silicon wafers and dried overnight at room temperature. Samples prepared in Milli-Q water were used to characterize nanoparticle dimensions, while dispersions in MES buffer were used to investigate the effect of acid phosphatase on nanoparticle stability. The resulting AFM images enabled direct nanoscale characterization of the particles, with nanoparticle sizes determined from the measured particle heights.

The use of a NanoWorld AFM probe in tapping mode provided a suitable approach for imaging these nanoscale polymer-based structures while limiting the interaction between the AFM probe and the deposited nanoparticles. The NanoWorld PointProbe® NCSTR-50 AFM probe therefore played an important role in confirming the morphology and dimensions of the lignin-TPP nanofertilizers.

This work highlights how NanoWorld AFM probes can support nanoscale characterization of responsive polymer nanoparticles and advanced agricultural materials. By combining AFM-based morphological analysis with biochemical response testing and plant experiments, the authors demonstrate a promising approach toward nanofertilizers capable of delivering phosphorus in a plant-growth-synchronized manner.

The study also illustrates the broader potential of nanoscale characterization in the development of responsive agricultural materials, where nanoparticle size, morphology, stability, and stimulus-dependent behavior can all influence the performance of the final delivery system.

Figure 6.AFM images of cross-linked lignin/TPP nanoparticles after A) 0 h, B) 24 h, C) 48 h, and D) 72 h of incubation with acid phosphatase (10 mU/mL). — Figure 6.
AFM images of cross-linked lignin/TPP nanoparticles after A) 0 h, B) 24 h, C) 48 h, and D) 72 h of incubation with acid phosphatase (10 mU/mL).

Full citation:
Boarino, A.; Carrara, N.; Clua, J.; Zahnd, N.; Poirier, Y.; Klok, H.-A.
Plant-Growth Synchronized, Acid Phosphatase-Responsive Lignin-Based Controlled Release Phosphorus Nanofertilizers.
Biomacromolecules 2026, 27, 5, 3176–3187.
https://doi.org/10.1021/acs.biomac.5c02594

Creative Commons license: CC BY 4.0

NanoWorld – A New Look for Our Product Labels

Starting August 1, 2026, NanoWorld will begin introducing updated designs for many of our product labels.

During the transition period, you may receive products with either the current or the new label design shown below. The label version simply reflects the ongoing implementation of our new labeling system and is not related to the product itself or its date of manufacture.

The updated labels continue to display the nominal resonant frequency and nominal force constant of each AFM probe and now include a QR code linking directly to the corresponding product page. This provides convenient access to the complete set of available AFM probe specifications and related technical product information.

Products with multiple cantilevers (such as the Pyrex-Nitride Series) and customized products will continue to use their current labels, reflecting their specific labeling requirements.

While the labels are changing, the AFM probes themselves remain the same. We hope this update makes it even more convenient to access product information when you need it.

Current NanoWorld AFM probe product label showing the nominal resonant frequency and nominal force constant. — Current product label for NanoWorld AFM probes.

Updated product label on NanoWorld ESD-safe AFM probe packaging featuring a QR code linking to product specifications.

Does the Hfq Protein Contribute to RNA Cargo Translocation into Bacterial Outer Membrane Vesicles?

Gram-negative bacteria release outer membrane vesicles (OMVs) that play a central role in host–pathogen interactions by transporting biomolecules, including proteins and nucleic acids. In this article, Marisela Velez and Véronique Arluison investigate the role of the RNA chaperone Hfq in mediating the interaction of small regulatory RNAs (sRNAs) with bacterial membranes.

In this article, it is shown that RNA binding to the inner membrane of Escherichia coli occurs in an Hfq-dependent manner. The study further demonstrates that membrane composition is a key factor in this process, with cardiolipin-rich lipid domains significantly enhancing RNA–membrane interactions. These findings provide new insight into the mechanism of RNA translocation from the cytoplasm to the periplasm, supporting its subsequent incorporation into OMVs.

Atomic force microscopy (AFM) was used to verify the formation and integrity of supported lipid bilayers and to monitor peptide–membrane interactions. Imaging was performed in tapping mode using a NanoWorld Pyrex-Nitride PNP-DB AFM probe with a resonance frequency of 15 kHz and a spring constant of 0.48 N/m. Measurements were carried out in liquid environment, enabling high-resolution characterization of biologically relevant membrane structures.

This work highlights the importance of AFM-based analysis for studying lipid–protein interactions and provides new understanding of RNA transport mechanisms in bacterial systems.

Figure 1
E. coli lipid bilayer incubated in the absence (A) or presence (B) of Hfq-CTR. Panel (A) shows the E. coli lipids bilayer. The height profile under the line shown on the upper image indicates that the domains are 0.8 nm higher than the rest of the membrane. The lower panel shows a three-dimensional representation of a small region. Panel (B) shows the E. coli lipid bilayer incubated in the presence of Hfq-CTR. The peptide accumulated on top of some of the domains, generating 1 nm high regions in some of them, as shown on the height profile. The arrows point the regions where the change in height occurs.

Full citation:
Velez, M.; Arluison, V.
Does the Hfq Protein Contribute to RNA Cargo Translocation into Bacterial Outer Membrane Vesicles?
Pathogens 2025, 14(4), 399.
https://doi.org/10.3390/pathogens14040399

License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)