查看更多>>摘要：Abstract Cancer is now responsible for the major leading cause of death worldwide. It is noteworthy that lung cancer has been recognised as the highest incidence (11.6%) and mortality (18.4%) for combined sexes among a variety of cancer diseases. Therefore, it is of great value to investigate the mechanical properties of lung cancerous cells for early diagnosis. This paper focus on the influence of measurement parameters on the measured central Young's moduli of single live A549 cell in vitro based on the force spectroscopy mode of atomic force microscopy (AFM). The effects of the measurement parameters on the measured central Young's moduli were analysed by fitting the force–depth curves utilising the Sneddon model. The results revealed that the Young's moduli of A549 cells increased with the larger indentation force, higher indentation speed, less retraction time, deeper Z length and lower purity percentage of serum. The Young's moduli of cells increased first and then decreased with the increasing dwell time. Hence, this research may have potential significance to provide reference for the standardised detection of a single cancerous cell in vitro using AFM methodologies.
查看更多>>摘要：Abstract The visualisation and quantification of pore networks and main phases have been critical research topics in cementitious materials as many critical mechanical and chemical properties and infrastructure reliability rely on these 3D characteristics. In this study, we realised the mesoscale serial sectioning and analysis up to ～80 μm by ～90 μm by ～60 μm on portland cement mortar using plasma focused ion beam (PFIB) for the first time. The workflow of working with mortar and PFIB was established applying a prepositioned hard silicon mask to reduce curtaining. Segmentation with minimal human interference was performed using a trained neural network, in which multiple types of segmentation models were compared. Combining PFIB analysis at microscale with X‐ray micro‐computed tomography, the analysis of capillary pores and air voids ranging from hundreds of nanometres (nm) to millimetres (mm) can be conducted. The volume fraction of large capillary pores and air voids are 11.5% and 12.7%, respectively. Moreover, the skeletonisation of connected capillary pores clearly shows fluid transport pathways, which is a key factor determining durability performance of concrete in aggressive environments. Another interesting aspect of the FIB tomography is the reconstruction of anhydrous phases, which could enable direct study of hydration kinetics of individual cement phases.
Masoumeh SouriMohammad Aref BagherzadehMirza Ali Mofazzal JahromiHossein Mohammad‐Beigi...
13页
查看更多>>摘要：Abstract The present research comes up with a novel DNA‐loaded poly‐L‐lysine (PLL)/hyaluronan (HA) nanocarrier (DNA‐loaded PLL/HA NCs) for gene delivery applications, as a promising candidate for gene delivery into diverse cells. A straightforward approach was employed to prepare such a nanosystem through masking DNA‐loaded PLL molecules by HA. Fourier‐transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), field emission‐scanning electron microscopy?(FE‐SEM) and transmission electron microscopy (TEM) were used to analyse the interaction of the molecules as well as the physicochemical properties of the NCs. The NCs showed a negative charge of –24 ± 3?mV, with an average size of 138 ± 6 nm, in an ellipsoid‐shape with smooth surfaces. The DNA loading efficiency (LE) measured by DNA absorbance was around 95 %. The MTT assay showed that the developed NCs are non‐toxic to the cells. Furthermore, the uptake of the DNA‐loaded PLL/HA NCs by the human embryonic kidney (HEK)‐293T cells was evaluated by a flow cytometry method, and demonstrated high potential cellular uptake over 90% for transferring the gene to HEK‐293T cells at the optimised conditions. Therefore, the DNA‐loaded PLL/HA NCs are the potent strategy for developing nanosystems for gene delivery applications.
查看更多>>摘要：Abstract Phase plates (PPs) in transmission electron microscopy (TEM) improve the contrast of weakly scattering objects under in‐focus imaging conditions. A well‐established PP type is the Zernike (Z)PP, which consists of a thin amorphous carbon (aC) film with a microscaled hole in the centre. The mean inner potential of the aC film is exploited to shift the phase of the scattered electrons while the unscattered electrons in the zero‐order beam propagate through the hole and remain unaffected. However, the abrupt thickness increase at the hole edge induces an abrupt change of the phase‐shift distribution and leads to fringing, that is, intensity oscillations around imaged objects, in TEM images. In this work, we have used focused‐ion‐beam milling to fabricate ZPPs with abrupt and graded thickness profiles around the centre hole. Depending on the thickness gradient and inner hole radius, graded‐ZPP‐TEM images of an aC/vacuum interface and bundles of carbon nanotubes (CNTs) show strongly reduced fringing. Image simulations were performed with ZPP‐phase‐shift distributions derived from measured thickness profiles of graded ZPPs, which show good agreement with the experimental images. Fringing artefacts, that is, intensity oscillations around imaged objects, are strongly reduced for Zernike phase plates with a graded thickness profile around the centre hole. Focused‐ion‐beam milling is used to fabricate graded Zernike phase plates with specific inner hole radius and thickness gradients. The phase‐shift distribution is obtained from measured thickness profiles around the centre hole. Image simulations based on experimentally measured thickness/phase‐shift distributions show good agreement with experimental Zernike phase‐plate TEM images.
NSTL
Wiley