Category: News

Mechanism for Vipp 1 spiral formation, ring biogenesis, and membrane repair

The ESCRT-III-like protein Vipp1 couples filament polymerization with membrane remodeling. It assembles planar sheets as well as 3D rings and helical polymers, all implicated in mitigating plastid-associated membrane stress. The architecture of Vipp1 planar sheets and helical polymers remains unknown, as do the geometric changes required to transition between polymeric forms. *

In the article “Mechanism for Vipp1 spiral formation, ring biogenesis, and membrane repair” Souvik Naskar, Andrea Merino, Javier Espadas, Jayanti Singh, Aurelien Roux, Adai Colom and Harry H. Low show how cyanobacterial Vipp1 assembles into morphologically-related sheets and spirals on membranes in vitro.*

The spirals converge to form a central ring similar to those described in membrane budding. Cryo-EM structures of helical filaments reveal a close geometric relationship between Vipp1 helical and planar lattices. Moreover, the helical structures reveal how filaments twist—a process required for Vipp1, and likely other ESCRT-III filaments, to transition between planar and 3D architectures. *

Overall, the authors’ results provide a molecular model for Vipp1 ring biogenesis and a mechanism for Vipp1 membrane stabilization and repair, with implications for other ESCRT-III systems. *

NanoWorld Ultra-Short Cantilevers USC-F0.3-k0.3  for High-Speed AFM (HS-AFM) with a typical spring constant of 0.3 N nm−1 and a typical resonance frequency of about 300 kHz were used for image acquisition with fast scanning atomic force microscopy.*

Fig. 2 from Souvik Naskar et al. 2024 “Mechanism for Vipp1 spiral formation, ring biogenesis, and membrane repair”:Vipp1 assembles dynamic networks of spirals, rings and sheets on membrane a, F-AFM phase timecourse showing Vipp1 recruitment to the highly curved edge of membrane patches. Scan rate, 70 Hz; 256 × 256 pixels. The area in the dashed box is enlarged in b. b, Spiral and ring formation localized to the membrane edge. Scan rate, 70 Hz; 256 × 256 pixels. c, Left, phase timecourse showcasing a dense network of sheets, spirals, and rings that ultimately cover the entire membrane plane. Right, average of six F-AFM height images. Scan rate, 120 Hz; 256 × 256 pixels. d, Average F-AFM height image showing Vipp1 sheet, spiral, and ring detail. Red arrows mark the sheet branching into filaments ~13 nm wide. Scan rate, 20 Hz; 256 × 256 pixels. e, Vipp1 sheet and spiral filament height offset from the membrane. f–i, Quantification of Vipp1 filament and spiral characteristics. n = 124, 13, 278, and 278 independent measurements for panels f, g, h, and i, respectively. Error bars show one s.d. of the mean. NanoWorld Ultra-Short Cantilevers USC-F0.3-k0.3-10 with a typical spring constant of 0.3 N nm−1 and a typical resonance frequency of about 300 kHz were used for image acquisition.
Fig. 2 from Souvik Naskar et al. 2024 “Mechanism for Vipp1 spiral formation, ring biogenesis, and membrane repair”:
Vipp1 assembles dynamic networks of spirals, rings and sheets on membrane
a, F-AFM phase timecourse showing Vipp1 recruitment to the highly curved edge of membrane patches. Scan rate, 70 Hz; 256 × 256 pixels. The area in the dashed box is enlarged in b. b, Spiral and ring formation localized to the membrane edge. Scan rate, 70 Hz; 256 × 256 pixels. c, Left, phase timecourse showcasing a dense network of sheets, spirals, and rings that ultimately cover the entire membrane plane. Right, average of six F-AFM height images. Scan rate, 120 Hz; 256 × 256 pixels. d, Average F-AFM height image showing Vipp1 sheet, spiral, and ring detail. Red arrows mark the sheet branching into filaments ~13 nm wide. Scan rate, 20 Hz; 256 × 256 pixels. e, Vipp1 sheet and spiral filament height offset from the membrane. f–i, Quantification of Vipp1 filament and spiral characteristics. n = 124, 13, 278, and 278 independent measurements for panels f, g, h, and i, respectively. Error bars show one s.d. of the mean.

*Souvik Naskar, Andrea Merino, Javier Espadas, Jayanti Singh, Aurelien Roux, Adai Colom and Harry H. Low
Mechanism for Vipp1 spiral formation, ring biogenesis, and membrane repair
Nature Structural & Molecular Biology (2024)
DOI: https://doi.org/10.1038/s41594-024-01401-8

Open Access The article “Mechanism for Vipp1 spiral formation, ring biogenesis, and membrane repair” by Souvik Naskar, Andrea Merino, Javier Espadas, Jayanti Singh, Aurelien Roux, Adai Colom and Harry H. Low is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Interfacial Engineering with One-Dimensional Lepidocrocite TiO2-Based Nanofilaments for High-Performance Perovskite Solar Cells

The optimization of nonradiative recombination losses through interface engineering is key to the development of efficient, stable, and hysteresis-free perovskite solar cells (PSCs). *

In the article “Interfacial Engineering with One-Dimensional Lepidocrocite TiO2-Based Nanofilaments for High-Performance Perovskite Solar Cells”  Shrabani Panigrahi, Hussein O. Badr, Jonas Deuermeier, Santanu Jana, Elvira Fortunato, Rodrigo Martins and Michel W. Barsoum, for the first time in solar cell technology, present a novel approach to interface modification by employing one-dimensional lepidocrocite (henceforth referred to as 1DL) TiO2-based nanofilaments, NFs, between the mesoporous TiO2 (mp TiO2) and halide perovskite film in PSCs to improve both the efficiency and stability of the devices. *

The 1DLs can be easily produced on the kilogram scale starting with cheap and earth-abundant precursor powders, such as TiC, TiN, TiB2, etc., and a common organic base like tetramethylammonium hydroxide. Notably, the 1DL deposition influenced perovskite grain development, resulting in a larger grain size and a more compact perovskite layer. Additionally, it minimized trap centers in the material and reduced charge recombination processes, as confirmed by the photoluminescence analysis. *

The overall promotion led to an improved power conversion efficiency (PCE) from 13 ± 3.2 to 16 ± 1.8% after interface modification. The champion PCE for the 1DL-containing devices is 17.82%, which is higher than that of 16.17% for the control devices. *

The passivation effect is further demonstrated by evaluating the stability of PSCs under ambient conditions, wherein the 1DL-containing PSCs maintain ∼87% of their initial efficiency after 120 days. *

The article not only presents cost-effective, novel, and promising materials for cathode interface engineering but also an effective approach to achieve high-efficiency PSCs with long-term stability devoid of encapsulation. *

To get a deeper understanding of the enhanced photocurrent production within the perovskite layer, the authors used photoconductive atomic force microscopy (pcAFM) to map the photocurrent distribution at the nanoscale for the same perovskite layers on both types of ETLs. *

pcAFM measurements were taken in air with a commercially available Atomic Force Microscopy by using conductive PtIr-coated NanoWorld Pointprobe® CONTPt silicon AFM probes (typical resonance frequency = 13 kHz, typical spring constant = 0.2 N/m) and a current detector holder. A light source was used to light the samples. *

Figure 4 from Shrabani Panigrahi et al. 2024 “Interfacial Engineering with One-Dimensional Lepidocrocite TiO2-Based Nanofilaments for High-Performance Perovskite Solar Cells”:Characterization of the perovskite films (MAPbI3 is denoted as MAPI inside figure) deposited on mp TiO2 and mp/1DL ETLs: (a, b) FESEM micrographs, (c) XRD patterns, (d) UV/vis absorption, and (e) PL spectra. (f, h) AFM topography images and (g, i) corresponding pcAFM photocurrent images of the perovskite layers deposited on mp TiO2 and mp/1DL TiO2 ETLS, respectively. (j) Photocurrent line profiles across the perovskite layers. pcAFM measurements were taken in air using conductive PtIr-coated NanoWorld Pointprobe® CONTPt silicon AFM probes
Figure 4 from Shrabani Panigrahi et al. 2024 “Interfacial Engineering with One-Dimensional Lepidocrocite TiO2-Based Nanofilaments for High-Performance Perovskite Solar Cells”:
Characterization of the perovskite films (MAPbI3 is denoted as MAPI inside figure) deposited on mp TiO2 and mp/1DL ETLs: (a, b) FESEM micrographs, (c) XRD patterns, (d) UV/vis absorption, and (e) PL spectra. (f, h) AFM topography images and (g, i) corresponding pcAFM photocurrent images of the perovskite layers deposited on mp TiO2 and mp/1DL TiO2 ETLS, respectively. (j) Photocurrent line profiles across the perovskite layers.

*Shrabani Panigrahi, Hussein O. Badr, Jonas Deuermeier, Santanu Jana, Elvira Fortunato, Rodrigo Martins and Michel W. Barsoum
Interfacial Engineering with One-Dimensional Lepidocrocite TiO2-Based Nanofilaments for High-Performance Perovskite Solar Cells
ACS Omega 2024, 9, 51, 50820–50829
DOI: https://doi.org/10.1021/acsomega.4c09516

Open Access The article “Interfacial Engineering with One-Dimensional Lepidocrocite TiO2-Based Nanofilaments for High-Performance Perovskite Solar Cells” by Shrabani Panigrahi, Hussein O. Badr, Jonas Deuermeier, Santanu Jana, Elvira Fortunato, Rodrigo Martins and Michel W. Barsoum is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third-party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.