Tag: 原子力显微镜探针

Cholesterol-regulated cellular stiffness may enhance evasion of NK cell-mediated cytotoxicity in gastric cancer stem cells

Gastric cancer has a high rate of recurrence, and as such, immunotherapy strategies are being investigated as a potential therapeutic strategy. *

Although the involvement of immune checkpoints in immunotherapy is well studied, biomechanical cues, such as target cell stiffness, have not yet been subject to the same level of investigation. *

Changes in the cholesterol content of the cell membrane directly influence tumor cell stiffness. *

In the article “Cholesterol-regulated cellular stiffness may enhance evasion of NK cell-mediated cytotoxicity in gastric cancer stem cells” Lijuan Zhu and Hongjin Wang investigate the effect of cholesterol on NK cell-mediated killing of gastric cancer stem-like cells. *

They report that surviving tumor cells with stem-like properties elevated cholesterol metabolism to evade NK cell cytotoxicity. *

Inhibition of cholesterol metabolism enhances NK cell-mediated killing of gastric cancer stem-like cells, highlighting a potential avenue for improving immunotherapy efficacy. *

This study suggests a possible effect of cancer cell stiffness on immune evasion and offers insights into enhancing immunotherapeutic strategies against tumors. *

Measurement of cell stiffness by AFM:

A customized commercially available atomic force microscope (AFM) and NanoWorld Pyrex-Nitride PNP-TR AFM probes were used for the measurement of cell stiffness by AFM. *

Atomic force microscopy cell stiffness was measured according to standard methodology. *

AFM force curves were captured with a customized AFM placed atop an inverted optical microscope that had a heating stage for live-cell imaging and a ×20 objective. Using an XY stage, the materials were moved until the desired cell, which could be observed under an optical microscope, was positioned beneath the AFM tip. Using a NanoWorld PNP-TR-B AFM cantilever (NanoWorld), the force curves on the cell were collected at a rate of ~ 5 μm·s−1 in the relative trigger mode (15 nm trigger threshold). *

By utilizing a thermal tuning and the deflection sensitivity of 170 nm·V−1, the AFM cantilever spring constant was determined to be 0.08 N·m−1. *

Single cells were measured both before and after treatment at 37 °C. The force curves were processed using the AFM’s analysis software, which also computed the Young’s modulus of the sample. This was accomplished by fitting the approach curve to an indentation of less than 500 nm (to account for stiffness) and assuming a cortical Poisson’s ratio of 0.3.*

NanoWorld Pyrex-Nitride PNP AFM probe - silicon nitride AFM cantilever and silicon nitride AFM tip
NanoWorld Pyrex-Nitride AFM probe series – AFM tip and AFM cantilever made of silicon nitride

*Lijuan Zhu and Hongjin Wang
Cholesterol-regulated cellular stiffness may enhance evasion of NK cell-mediated cytotoxicity in gastric cancer stem cells
FEBS Open Bio, Volume 14, Issue 5, May 2024, Pages 855-866
DOI: https://doi.org/10.1002/2211-5463.13793

Open Access  The article “Cholesterol-regulated cellular stiffness may enhance evasion of NK cell-mediated cytotoxicity in gastric cancer stem cells” by Lijuan Zhu and Hongjin Wang 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/.